Paper and Biomaterials -->Research Articles

Behavior of Decayed Spruce (Picea abies) during Kraft Pulping

Halonen Markku,Alén Raimo — 2021/1/25 17:32:13

This study indicated that by applying an improved classification system to decayed large-diameter Norway spruce (Picea abies) wood, its use as raw material for kraft pulping without loss of pulp quality could be essentially increased. This is based on the fact that although the cooking yield of decayed spruce material which has been sorted according to these new recommendations is somewhat lower and Kappa number higher than those of sound wood material, the greatest part of the decayed stem (the outer part of the stem) contains long-fiber wood material which produces pulp of good quality. Therefore, large-diameter spruce logs can also be separately used, for example, in the manufacture of reinforcement pulp.

Biotreatment of Wastewater from Soda-pretreatment Process of Corn Stover Using White-rot Fungus Z-6

Li Xuezhi,Zhao Jian — 2021/1/25 17:32:14

Alkaline pretreatment of straw materials prior to enzyme hydrolysis is a key step for bioconversion of lignocellulose to bioethanol and chemicals. Wastewater from the alkaline pretreatment process must be treated before discharge to minimize its environmental impact. In this study, biotreatment of the wastewater from soda-pretreatment process of corn stover was investigated using fungus Z-6, and some indexes such as color, chemical oxygen demand (COD), and lignin content of wastewater before and after biotreatment were determined to assess the effect of the biotreatment. Results showed that fungus treatment could remove color up to approximately 72% after 2 d, and decrease COD and lignin content by about 63% and 60%, respectively after 3 d. The wastewater was fractionated using dynamic ultrafiltration method, and the changes in lignin contents of the effluent fractions with different molecular weights before and after biotreatment were analyzed. Some compounds produced by the fungus during treatment were identified using gas chromatography-mass (GC-MS) spectrometer, which revealed that depolymerization of lignin occurred during the biotreatment process.

Optical and Mechanical Properties of CMCNF-dispersed MMT/CMC-Na Nanocomposite Films: Influence of the Degree of Substitution of CMCNFs

Li Guanhui,Hou Gaoyuan,Xie Hong,Zhang Dejian,Cui Jinyi,Fang Zhiqiang — 2021/1/25 17:32:13

Carboxymethylated cellulose nanofibril (CMCNF) is an effective green dispersant to prepare well-dispersed monolayer montmorillonites (MMTs) in water, thereby facilitating the preparation of a high-performance MMT/polymer nanocomposite film. However, not enough attention has been paid to correlating the degree of substitution (DS) of CMCNFs with the mechanical and optical properties of the final nanocomposite films. In this study, a series of homogeneous monolayer MMT nanoplatelet dispersions was prepared initially using CMCNFs with different DS as a dispersant, and the as-prepared CMCNF-dispersed MMT dispersions were then mixed with sodium carboxymethyl cellulose (CMC-Na) to fabricate nacre-like nanocomposite films with different contents of MMTs through self-assembly. The layered nanostructure and optical and mechanical properties of the as-prepared CMCNF-dispersed MMT/CMC-Na nanocomposite films were investigated, which demonstrated that CMCNFs with lower DS have a positive effect on their optical and mechanical properties. This study sheds light on the preparation of MMT-based nanocomposite films with superior optical and mechanical properties.

Triethylamine-catalyzed Isomerization of Glucose to Fructose under Low Temperature Conditions in Aqueous Phase

Zhang Xiao,Cheng Banggui,Lin Qixuan,Wang Xiaohui,Li Rui,Ren Junli — 2021/1/25 17:32:15

Isomerization of glucose derived from lignocellulosic biomass is an important step in biorefinery. Fructose isomerized from glucose, is used as a highly attractive sweetener in the food and beverages industries. However, the prevalence of side reactions at high glucose concentrations is a serious issue, leading to a significant reduction in the fructose yield, especially in the aqueous phase. In this study, an efficient method for the conversion of highly concentrated glucose into fructose under low temperature conditions using triethylamine as the catalyst was developed. It was demonstrated that high fructose yield could be maintained at high glucose concentration. At 60℃, fructose yield of 38.7% and fructose selectivity of 80.6% were achieved in 1 mol/L (approximately 17 wt% ) glucose. When glucose concentration was increased to 2 mol/L (approximately 31 wt%), the fructose yield and selectivity were maintained at 34.7% and 77.4%, respectively. ¹³C nuclear magnetic resonance (NMR) spectrometer was used to examine the glucose isomerization reaction. Compared to the NaOH catalytic system, triethylamine acted as a buffer to provide a stable alkaline environment for the catalytic system, further maintaining a high level of catalytic efficiency for the isomerization of glucose to fructose.

Preparation of Hydroxypropyl Methylcellulose Acetate Succinate with a Narrow Molecular Weight Dispersion

Zhang Liangliang,Fu Shiyu — 2021/1/25 17:32:16

Hydroxypropyl methylcellulose acetate succinate (HPMCAS) was successfully synthesized from the reaction of hydroxypropyl methylcellulose with succinic anhydride and acetic anhydride in an acetone/pyridine system. Products with different contents of succinyl groups and acetyl groups were prepared by varying the reaction conditions. In the acetone/pyridine system, equipment corrosion does not occur, the product is easy to wash, and the solvent can be recycled. By varying the concentration of the esterifying agents, products with different ratios of acidic groups can be obtained. Under the optimum conditions, the obtained products had an average molecular weight between 5.39×10⁴ and 5.41×10⁴, a number average molecular weight from 4.97×10⁴ to 5.13×10⁴, and a polydispersity index from 1.05 to 1.08. The products dissolved well in acetone and methanol, and formed films on a mold. The films had good pH-sensitivity, tensile strength, and thermal stability. The formed films could dissolve in solutions with a pH value ranging from 5.4 to 6.4, and are therefore suitable for use as an enteric coating for pharmaceutical dosage forms.

Etherification of Alkali-pretreated Sugarcane Bagasse Cellulose in Tetrahydrofuran

Fu Shiyu,Xie Chuanlong — 2020/7/22 9:14:06

Sugarcane bagasse (SCB) is an important by-product in the sugar industry. It is a source of cellulose fibers or cellulose for paper mills and textiles factories. In this study, SCB was ethyl etherified in tetrahydrofuran (THF) after alkali pretreatment. The alkali concentration for the pre-treatment, the ratio of ethyl bromide (EtBr) to dried SCB in the reaction, reaction time, and temperature were investigated for the etherification of SCB. The ethoxyl content and characterization of the product were determined using headspace gas chromatography (HS-GC), Fourier Transform Infrared (FT-IR) and ¹³C-NMR spectroscopy, respectively. It was found that SCB was well-etherified with EtBr in alkali-THF. Upon ethylation of SCB, the ethoxyl content of the product was high when the alkali concentration and the ratio of EtBr to dried SCB were controlled from 50% to 75% and 4:1 (V/w) to 6:1 (V/w), respectively. The reaction occurred optimally when the temperature was controlled below 110℃; above this temperature, the degree of etherification decreased. The thermal stability of ethylated SCB was higher than that of SCB but slightly lower than that of commercial ethyl cellulose. Ethylated SCB has the potential to form composites with many materials because it is soluble in a wide variety of solvents.

Effect of Thermal Treatment on the Properties of TEMPO Oxidized Cellulose Film for the Flexible Substrate of Solar Cell

Lin Changmei,Zhang Hui,Deng Qidu,Huang Liulian,Ma Xiaojuan,Cao Shilin — 2020/7/22 9:14:07

The 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose film (TOCF) has been attempted to be used as a substrate in electronic and optoelectronic devices, but the changes in the TOCF properties before and after annealing treatment have usually been neglected during device fabrication. In this study, TOCF was treated in different atmospheres (air, vacuum, and N₂) and at different temperatures, and the properties were investigated. The results indicate that the optical properties are slightly affected by atmosphere and temperature; only slight transmittance loss and haze increase have been observed when TOCF is exposed to an air atmosphere at temperatures of above 120℃. In contrast to the slight effects on the optical properties, cellulose degradation and a loss of film strength have been observed regardless of the atmosphere used when placed at temperatures of above 100℃. Specifically, TOCF was exposed to air, followed by N₂ and vacuum atmospheres. Additional Fourier transform infrared (FT-IR) and nuclear magnetic resonance (NMR) results showed that increasing the temperature had no significant effect on the structure of TOCF. Therefore, the annealing temperature should be controlled at a temperature of lower than 100℃ and a vacuum atmosphere is preferred.

Effects of MFC-modified GCC as Filler on the Opacity of Pulp Handsheets

Su Yanqun,Liu Junjie,Liu Jingang,Zhang Ruijuan,Chen Jinghuan,Du Yanfen — 2020/7/22 9:14:09

Microfibrillated cellulose (MFC) was obtained by mechanical grinding of different pulps. MFC-modified ground calcium carbonate (GCC) was prepared in two different ways, designated MFC-GCC composite filler and MFC-GCC flocs filler. The opacity of pulp handsheets loaded with MFC-modified GCC was measured. The effects of MFC originated from different pulps, pretreatment method, and filler modification on the opacity of handsheets loaded with MFC-modified GCC were discussed. The results show that MFC originated from alkaline peroxide mechanical pulp (APMP) was optimal for improving the opacity of the handsheets and PFI grinding pretreatment for MFC provided a denser structure in the corresponding MFC_APMP-GCC floc filler while enzyme pretreatment was more effective in increasing the opacity of the filled paper. Under the experimental conditions, the opacity of handsheets increased from 81.0% to 82.7% when the unmodified GCC was replaced by an equivalent amount of MFC_APMP-GCC composite filler, while other properties were unchanged.

Coaxing Polysaccharide Granules into Supramolecular Biocolloidal Additives for Papermaking

2020/5/14 0:00:00

In light of developments in polysaccharide-based sustainable processes involving supramolecular interactions, we herein present our findings pertaining to coaxing polysaccharide granules into functional supramolecular biocolloids. Translucent biocolloidal dispersions containing various forms of starch are facilely designable, essentially built upon complexation between disassembled native cornstarch granules and amphiphilic ligands. Oily moieties of guest molecules are dynamically attractable into cavities of helical structures, with cationic groups pointing toward the bulk phase. This noncovalent attraction can generate core-shell biocolloidal particles. The significantly higher gelatinizability of freeze-dried biocolloids in contrast to native cornstarch granules is attributable to complex formation, and a homogenous dispersion is readily formable at room temperature. Our results also show biocolloids’ ligand-related antibacterial activity. The use of biocolloids as wet-end additives for biofiber assemblies (cellulosic paper) can enhance mechanical strength, fines retention, and filler bondability. Supramolecular biocolloids with positively charged, translucent, easily gelatinizable, antibacterial, and polysaccharide-bondable functionalities would find tailo-rable use in the paper industry.

Facile Fabrication of Cellulosic Paper-based Composites with Temperature-controlled Hydrophobicity and Excellent Mechanical Strength

Yun Tongtong,Wang Yilin,Lu Jie,Cheng Yi,Lyu Yanna,Wang Haisong — 2020/5/14 0:00:00

In this paper, we presented a novel strategy to employ a plant-derived carbohydrate polymer, i. e., cellulose, to prepare a hydrophobic composite. Cellulose was used as a scaffold, and ethylene-propylene side by side (ES) fiber was thermally melted and then coated on the cellulose surface to achieve hydrophobicity. Experimental results revealed that the thermo-coating ES fibers greatly increased the water contact angle of the cellulose scaffold from 25° to 153° while simultaneously enhanced the wet tensile strength of the composite approximately 6.7-fold (drying temperature of 170℃) compared with the pure cellulose paper. In particular, compared with other related research, the prepared cellulose-based composite possessed excellent hydrophobicity and superior mechanical strength, which introduces a new chemical engineering approach to prepare hydrophobic cellulose-based functional materials.

Pore Structure Regulation of Carboxyethylated Microfibrillated Cellulose Films

Li Meican,Chen Jinghuan,Liu Jingang,Xu Zehong,Su Yanqun,Zhang Ruijuan,Du Yanfen — 2020/5/14 0:00:00

Carboxyethylation is a recent chemical pretreatment for preparation of microfibrillated cellulose (MFC). The carboxyethylated MFC film prepared by coating method has compact structure and high mechanical properties. In order to expand its application, three approaches including using organic solvents, different drying methods and cationic additives, have been adopted in this paper to enrich and regulate the pore structure of MFC film. The results show that all the approaches can improve the pore structure but decrease the mechanical properties of MFC film. When organic solvents such as ethanol, isopropanol and n-butanol were used to replace the water in MFC suspension or pre-dried MFC film, the pore structure of films were increased. Additionally, the film obtained by freeze-drying or air-drying after freezing in liquid nitrogen or freezer has high porosity but poor strength. The best drying process is to rewet dry MFC film, freeze in liquid nitrogen and then freeze-dry. Moreover, the addition of cationic polyelectrolytes or alkene ketone dimer (AKD) in MFC suspension can also significantly increase the film’s porosity. Through the above approaches, the porosity of carboxyethylated MFC film can be regulated between 20% and 90%.

Preparation and Characterization of Natural Bamboo Fiber

Li Kaixuan,Miao Qingxian,Zhao He,Yang Jiawei,Cheng Haitao,Chen Lihui — 2020/5/14 0:00:00

In this study, natural bamboo fiber was prepared combining chemical pretreatment with mechanical disc refining, opening, and carding. An orthogonal experiment was designed based on four factors and three levels; thereafter, the manufacturing process was optimized. The length, diameter, tensile strength, and elastic modulus of the bamboo fiber were determined, and the crystallinity and morphology of the fiber were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the optimum parameters for the chemical pretreatment were a cooking temperature of 130℃, heating time of 2 h, NaOH dosage of 2%, and Na₂SO₃ dosage of 10%. The cooking yield of bamboo chips was 89.5%, and the carding yield of natural bamboo fiber was 43.0% under the optimum conditions. The length, diameter, tensile strength, and elastic modulus of the obtained fiber were 36.71 mm, 0.285 mm, 407 MPa, and 27.7 GPa, respectively. XRD analysis and SEM observations showed that the technology used in this study can produce bright and compact natural bamboo fibers with high crystallinity.

Characteristics of Carboxymethyl Hemicellulose (CMX) and Its Strengthening Mechanism

Wu Shubin,He Wanli,Song Feiyu — 2020/5/14 0:00:00

In this study, three kinds of rough-wrought hemicelluloses (RHCs) were obtained via alkali extraction on different raw materials. One was untreated Phyllostachys edulis powder; the second was obtained via benzyl alcohol extraction of Phyllostachys edulis powder; and the third was holocellulose of Phyllostachys edulis powder. Carboxymethyl hemicelluloses (CMXs) were prepared by the alkalization and etherification of RHCs and were used to enhance the tensile strength of household paper. The results demonstrated a synergistic effect between CMX and polyamide epichlorohydrin resin (PAE), and the addition of small amount of CMX (0.35 kg/t pulp) can significantly improve the dry and wet tensile indices of paper. Study results of CMX strengthening mechanism revealed that the addition of CMX can improve the retention of PAE, especially the fine fiber, due to the adsorption of charges. The use of CMX in paper not only saves production costs but also reduces the proportion of long fiber, which is beneficial to the closed circulation and treatment of white water.

Synthesis of Fe³⁺-doped Aminated Lignin as A Peroxidase Mimic for Colorimetric Detection of H₂O₂ and Glucose

Lijun Li,Xin Liu,Yixin Shi,Jinhui Pang,Jun Yang,Feng Xu,Xueming Zhang — 2021/10/15 13:39:07

Peroxidase plays an important role in living systems; however, its storage difficulty and easy inactivation have limited its applications in complex environments. To address these problems, herein, we proposed a method to synthesize peroxidase mimics by amination, carbonization, and Fe³⁺-doping of industrial alkali lignin. The Fe³⁺-doped lignin-based peroxidase mimic (Fe-LPM), with active centers of coordination between Fe³⁺ and N atoms, showed higher tolerance to pH value and temperature than natural peroxidase. Using Fe-LPM, 10-100 mmol/L of H₂O₂ and glucose could be colorimetrically detected with the lowest detection limits of 80 μmol/L and 1.5 mmol/L and visual detection limits of 1.0 mmol/L and 10 mmol/L, respectively. The Fe-LPM maintained peroxidase-like activity after 10 cycles and could even be used for H₂O₂ detection in practical samples. This work not only provides a new approach to synthesize peroxidase mimics using biomass materials but also promotes the high-value utilization of lignin.

Preparation of High-precision Electrospun Nanoair Filter Paper for Air Purification

Weiyin Su,Lanfeng Hui,Xiaoyan Ma,Lingyuan Wang,Yu Wang — 2021/10/15 13:39:10

Electrospinning technology has become a research hotspot because of its advantages, such as simple operation, low cost, large specific surface area, high porosity, and good fiber continuity. Here, a new type of composite nanoair filter paper was prepared using electrospinning technology. To improve the practicability of air filter base paper, phenolic resin was used as a curing agent to improve the strength. The results show that the electrospun nanoair filter paper with air filter paper as the receiving substrate and polyvinyl alcohol (PVA) solution as the spinning solution excellently performed in all aspects. The influence of the thickness (spinning time) of the PVA nanofiber membrane on the micromorphology, physical properties, and filtration performance of the electrospun nanoair filter paper was analyzed. According to the ISO 5011-2014 standard, the initial resistance, filtration efficiency, mean pore size, and dust capacity of the electrospun nanoair filter paper were 77.3 Pa, 99.9941%, 3.50 μm, and 146 g/m², respectively, when the spinning time was 15 min.

Transparent Photochromic Wood Composites Incorporating AgBr Nanoparticles for UV-shielding Applications

Cong Zhang,Yujun Ma,Tao Lin,Xuefeng Yin,Xiaoyao Wei,Zhongxiang Wang — 2021/10/15 13:39:04

Transparent wood (TW) is a wood-based biomaterial with several advantages, such as high optical transmittance, low thermal conductivity, and tunable haze. TW is functionalized according to its transparency to broaden its applications in different fields. Several studies have examined wood functionalization in recent years; however, few studies have reported photochromic TW (PTW) for ultraviolet (UV) -shielding window applications. Herein, PTW was obtained by infiltrating the delignified wood template with photochromic silver bromide (AgBr) nanoparticles and a pre-polymerized methyl methacrylate (MMA) mixture solution. The obtained PTW can adjust the luminous flux on change in the color in the visible light region. The photochromic properties were examined, and the optical properties of the composites were characterized using UV-Vis spectrophotometry. Light transmittance of PTW was up to 86.5% at 800 nm before UV irradiation, and it decreased to 70.1% at 800 nm after UV irradiation, as the wood color changed from colorless to dark purple under UV irradiation. Thus, this work not only achieves high-value utilization of wood, but also produces a new material that can be used in varied fields, such as UV-shielding, energy saving, and smart building.

Interaction between PCC Filler and Cellulosic Fiber in Fiber/Filler Co-refining System

Sheng Qiang,Shunxi Song,Peiyao Wang,Yujie Shi,Linhao Li,Haitang Liu — 2021/10/15 13:39:08

Mineral fillers are important for conserving raw fiber materials and reducing production costs in the paper industry. However, the increase in filler content will inevitably result in strength reduction, which limits the adding amount of filler in paper production. In this study, we designed a cellulose fiber/filler co-refining approach to improve the strength and optical properties of paper; moreover, the synergistic interaction between fibers and precipitated calcium carbonate (PCC) fillers in the co-refining process was investigated. Results of fiber separation and PCC particle size analysis showed that, compared with conventional refining, the content of fines increased, whereas the PCC particle size decreased. More importantly, composites were formed between the PCC and fines, which promoted strength improvement of paper. Physical tests show that the tensile index of paper with 15% PCC content increased by 22% compared with that of the paper filled by conventional method, whereas the brightness and opacity of paper improved by fiber/filler co-refining for a specified filler content. These findings provide a basis for the further development of co-refining filling technology.

Preparation and Properties of Nano-cellulose/Sodium Alginate Composite Hydrogel

Peiyi Li,Ruiyan Liu,Haozhe Lei,Miaomiao Zhou,Boxing Jian,Xinping Li — 2021/10/15 13:39:03

Cellulose nanofiber (CNF) was isolated from Okara using deep eutectic solvent (DES) with high-speed stirring. The composite hydrogels obtained by using different proportions of CNF and sodium alginate (SA) had different properties. The CNF/SA composite hydrogels were analyzed using Fourier transform infrared spectroscopy and scanning electron microscopy and tested for compression properties, rheological properties, water content, and swelling degree. Physical crosslinking between SA and Ca²⁺, and different degrees of hydrogen bond formation between SA and CNF were observed. The CNF/SA composite hydrogel have great potential as reinforcements in eco-friendly composite hydrogels for diverse applications.

Numerical Simulation of Microwave-assisted Depolymerization of Kraft Lignin

Zhenhao Ma,Wenliang Wang,Jiale Huang,Yujun Ma,Hui Miao,Yishuai Fu,Xiaoxiao Ren — 2021/10/15 13:39:06

Kraft lignin has the potential to replace traditional fossil resources for the preparation of high-value chemicals because it is rich in aromatic rings and active functional groups. An effective method for the pyrolysis of kraft lignin into chemicals/fuels is microwave-assisted depolymerization. A simulation model is urgently needed to illustrate the coupling effect and mechanism of lignin conversion during the depolymerization process. In this study, COMSOL Multiphysics was used to simulate the microwave-assisted depolymerization process. The results showed that microwave power had a significant effect on the electric field and temperature distribution in the microwave cavity, while the reaction time had little effect on the electric field. The effect of the nitrogen flow rate on the electric field and temperature was negligible. The intensity of the electric field, heating rate of lignin, and final temperature of lignin depolymerization increased with increasing microwave power.

Synthesis of Lignin-based Non-isocyanate Poly(imine-hydroxyurethane)s Networks. Part II: Self-healing, Reprocessing, and Degradation

Chao Shen,Bailiang Xue,Danwei Xue,Rui Tang,Wei Zhao,Xinping Li — 2021/7/14 18:02:01

This study provides a comprehensive understanding of the polymeric properties of lignin-based non-isocyanate poly(imine-hydroxyurethane)s (LNIPUs). The properties of the LNIPUs are affected by changes in the stoichiometric feed ratios of the bis(6-membered cyclic carbonate) (BCC) and levulinate enzymatic hydrolysis lignin (LEHL). The results showed that the LNIPUs exhibited a short relaxation time and excellent thermal repair and degradation properties. With a change in the LEHL content in the LNIPUs to 45.53%, a relaxation time of only 9 s was achieved, and the thermal repair rate of the scratches reached 93%. Furthermore, the tensile strength of the LNIPUs decreased with an increase in the LEHL content after two hot-pressing processes, while a higher than 75% tensile strength was maintained after the second hot-pressing treatment. The LNIPUs exhibited thermoresponsive shape memory property with deformation and shape fixing at 80℃. In addition, the as-synthesized LNIPUs were soluble in ethylene glycol in the absence of any organic solvents. This work demonstrates the synthesis of LNIPUs with self-healing, reprocessing, shape memory, and degradation properties.

Improving Electrochemical Performance of Cellulose Fiber-based Supercapacitor Electrode Using Polypyrrole-wrapped Iron Oxyhydroxide

Youngchu Kang,Hailan Jin,Xianhui An,Xueren Qian — 2021/7/14 18:01:44

Polypyrrole (PPy)@cellulose fiber-based composites have been widely investigated as electrode materials for use in flexible supercapacitors. However, they cannot readily provide high specific capacitance and cyclic stability owing to their inherent drawbacks, such as high resistance, Weber impedance, and volume expansion or collapse during charging/discharging. In this study, iron oxyhydroxide (FeOOH) is incorporated in the abovementioned composite to decrease the equivalent series resistance, charge transfer resistance, and Weber impedance, thereby enhancing electron transfer and ion diffusion, which results in superior electrochemical performance. The PPy-wrapped FeOOH@cellulose fiber-based composite electrode with the molar ratio of FeSO₄ to NaBH₄ of 1∶1 exhibits a high specific capacitance of 513.8 F/g at a current density of 0.2 A/g, as well as an excellent capacitance retention of 89.4% after 1000 cycles.

Evaluation and Improvement of Antioxidant Activity of Water-soluble Lignin Products from Steam Explosion Processing of Corn Stalk

Hao Sun,Rui Wang,Guanhua Wang,Wenjie Sui,Chuanling Si — 2021/7/14 18:02:02

In this study, corn stalk was pretreated by steam explosion under various processing conditions, and the antioxidant activity of hydrolysates in the post-process washing liquor was analyzed using the 1,1'-diphenyl-2-picrylhydrazyl (DPPH?) scavenging method. The yield and composition of the hydrolysates obtained under different treatment conditions were also determined; the results indicated that the steam explosion extent had a significant effect on both properties. Under optimized conditions (1.5 MPa, 20 min), the obtained hydrolysate had the highest phenolic compound yield (18.6 mg/g untreated corn stalk) and the highest radical scavenging capacity (IC₅₀=0.24 mg/mL). To confirm the positive effect of phenolic compounds on the antioxidant activity of the hydrolysate, one-step ethanol fractionation was carried out. Due to the enrichment of phenolic compounds, the ethanol-soluble fraction (ESF) exhibited significantly enhanced antioxidant activity with an IC₅₀ value of 0.06 mg/mL, which was close to that of butylated hydroxytoluene (BHT, IC₅₀ = 0.056 mg/mL). Consequently, this work indicated that phenolic compounds have a significant effect on the antioxidant activity of hydrolysate from steam-exploded corn stalk and that simple one-step ethanol fractionation is an effective way to enrich the phenolic compounds in the hydrolysate and improve the antioxidant activity.

Solvent-enhanced Depolymerization of Lignin under Microwave Irradiation

Wenliang Wang,Jiale Huang,Xingjin Zhao,Xiaoxiao Ren,Hui Miao — 2021/7/14 18:01:48

Lignin is considered an ideal natural material for the production of sustainable monophenols. In this study, a microwave-assisted depolymerization (MAD) strategy was developed. The introduction of solvent vapors in the dynamic vapor flow reaction system was performed to enhance the lignin conversion efficiency. The results showed that no liquid products were generated from the MAD of lignin without solvent vapors. With the introduction of solvents (CH₃OH, HCHO, HCOOH, and CH₂Cl₂), liquid products appeared (especially with CH₂Cl₂, which had the highest yield of 41.9 wt%). Results from gas chromatography/mass spectrometry of liquid products showed that seven kinds of compounds, including guaiacols, phenols, syringols, methoxyphenyls, heterocycles, esters, and aromatics were identified. CH₂Cl₂ can significantly enhance the production of monophenols (guaiacols, phenols, and syringols). The introduction of these solvent vapors can also facilitate the generation of porous char with high Brunauer-Emmett-Teller specific surface areas. Some carbon nanospheres deposited on the surface of the char were obtained with the assistance of CH₂Cl₂. This study provides a facile method for the utilization of lignin in the field of bio-based fine chemicals.

Preparation and Characterization of Hydrophobic Bagasse Hemicellulose-based Films

Chaoxian Zhou,Mingchang Gao,Gengmei Liu,Chen Zhang,Yang Liu,Qingxian Miao — 2021/7/14 18:01:50

To improve the hydrophobicity of bagasse hemicellulose-based films, glutaraldehyde was applied when preparing films of original and cationic bagasse hemicellulose with the addition of polyvinyl alcohol and sorbitol. The results showed that the cationic modification could increase the hydrophobicity of the hemicellulose-based film, and the hydrophobicity of hemicellulose-based films crosslinked with glutaraldehyde also increased. However, cationic modification of hemicellulose decreased the stress of the hemicellulose-based film. While crosslinking with glutaraldehyde increased the stress of both the original and cationic hemicellulose-based films. Macrophotography indicated that the film formability of the original hemicellulose was better than that of cationic hemicellulose. Through SEM observation, the degree of bonding of different components of the films was found to be increased due to crosslinking with glutaraldehyde. The crosslinking reaction between glutaraldehyde and hemicellulose was further confirmed by FT-IR spectroscopy.

Comprehensive Evaluation and Prediction of the Effectiveness of H₂O₂-assisted Na₂CO₃ Pretreatment of Corn Stover Using Multivariate Analysis

Xiaoyan Feng,Xuejin Xie,Yidong Zhang,Guang Yu,Chao Liu,Bin Li,Qiu Cui — 2021/4/16 16:12:43

In this study, multivariate analysis methods, including a principal component analysis (PCA) and partial least square (PLS) analysis, were applied to reveal the inner relationship of the key variables in the process of H₂O₂-assisted Na₂CO₃ (HSC) pretreatment of corn stover. A total of 120 pretreatment experiments were implemented at the lab scale under different conditions by varying the particle size of the corn stover and process variables. The results showed that the Na₂CO₃ dosage and pretreatment temperature had a strong influence on lignin removal, whereas pulp refining instrument (PFI) refining and Na₂CO₃ dosage played positive roles in the final total sugar yield. Furthermore, it was found that pretreatment conditions had a more significant impact on the amelioration of pretreatment effectiveness compared with the properties of raw corn stover. In addition, a prediction of the effectiveness of the corn stover HSC pretreatment based on a PLS analysis was conducted for the first time, and the test results of the predictability based on additional pretreatment experiments proved that the developed PLS model achieved a good predictive performance (particularly for the final total sugar yield), indicating that the developed PLS model can be used to predict the effectiveness of HSC pretreatment. Therefore, multivariate analysis can be potentially used to monitor and control the pretreatment process in future large-scale biorefinery applications.

Highly Conductive Fractal-structured Silver Particles for Preparing Flexible Printed Circuits via Screen Printing

2021/4/16 16:12:46

Fractal-structured silver particles (FSSPs) are conductive materials with a micron-scale trunk and nanoscale branches, and are characterized with high electrical conductivity and high connectivity. In this study, FSSPs were added to an aqueous additive solution for synthesizing a conductive ink, which was used to prepare two types of printing electrodes via screen printing. The first type included two flexible printed electrodes (FPEs): an FPE on a polyethylene terephthalate (PET) film and an FPE on paper. The second one was a polydimethylsiloxane (PDMS)-embedded FPE. The PET-based FPE exhibited high electrochemical stability when its sheet resistance was 0.38 Ω/sq for a 50% (w/w) content of FSSPs in the prepared conductive ink. Moreover, the embedded FPE demonstrated excellent mechanical properties and high chemical stability. In addition, the embedded structure was endowed with stretchability, which is important for different devices, such as flexible biomedical sensors and flexible electronics.

Conversion of Bioethanol to Olefins over ZrO₂ Catalyst

Meixiang Gao,Jiaqi Xiao — 2021/4/16 16:12:40

Ethylene and 1,3-butadiene are important organic chemical raw materials. Petroleum hydrocarbon cracking is the most widely used method for ethylene fabrication worldwide. In this study, the use of a ZrO₂ catalyst, which can be easily synthesized, for the efficient conversion of bioethanol to ethylene and 1,3-butadiene was analyzed. X-ray diffraction, transmission electron microscopy, temperature-programmed desorption, and Fourier-transform infrared spectroscopy analyses were used to evaluate the surface properties of ZrO₂. The selectivity of ZrO₂ toward ethylene and 1,3-butadiene was as high as 98.2%. Catalyst selectivity toward dehydration or dehydrogenation products depends on the nature of the weak acid-base catalytic sites, whereas high-strength base and intermediate-strength acid catalytic sites selectively yield ethylene.

Green and Effective Ammonium Carbonate-assisted Process for Drying Hemicellulose Obtained through Alkali Extraction of Bleached Bamboo Kraft Pulp

2021/1/25 11:31:53

Hemicellulose has a wide range of applications, including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films. Hemicellulose is usually present as a spent liquor, such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers. Due to its dilute nature, hemicellulose needs to be dried for practical utilization, and this is challenging. In this study, cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process. Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process. The effects of drying time and drying temperature were determined. Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose, as revealed by detailed Fourier transform infrared and X-ray diffraction analyses. The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method, and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose. The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films.

Synthesis of Reprocessable Lignin-based Non-isocyanate Poly(imine-hydroxyurethane)s Networks

Xue Danwei,Xue Bailiang,Tang Rui,Shen Chao,Li Xinping,Zhao Wei — 2021/1/25 11:31:45

In this study, an environmentally friendly and non-toxic route to synthesize lignin-based non-isocyanate poly(imine-hydroxyurethane)s networks was explored. Specifically, the NH₂-terminated polyhydroxyurethanes (NPHUs) prepolymer was first synthesized from bis(6-membered cyclic carbonate) (BCC) and diamine via the ring-opening reaction. Subsequently, the corresponding lignin-based non-isocyanate polyurethanes (NIPUs) with tunable properties were synthesized from NPHUs and levulinate lignin derivatives containing ketone groups via the Schiff base reaction. The structural, mechanical, and thermal properties of NIPUs with different stoichiometric feed ratios of BCC and levulinate lignin were characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The results indicated that the tensile strength, Young's modulus, toughness, storage modulus, glass transition temperature, and thermal stability of lignin-based NIPUs gradually increased with increasing lignin content, and the highest Young's modulus of 41.1 MPa was obtained when lignin content reached 45.53%. With good reprocessing properties, this synthetic framework of lignin-based NIPUs also provides sustainable non-isocyanate-based substitutions to traditional polyurethane networks.

Carboxyethylated Microfibrillated Cellulose Fibers Prepared from Different Raw Materials

Chen Jinghuan,Liu Jingang,Hou Leilei,Xu Zehong — 2021/1/25 11:31:47

Carboxyethylation pretreatment was used to prepare microfibrillated cellulose (MFC) in this study. In order to evaluate the adaptability of this pretreatment method, carboxyethylated MFC was prepared from six different cellulosic materials. The carboxyl content, degree of polymerization, water retention value, charge density, chemical structure, size distribution, and micromorphology of the materials before and after pretreatment and grinding were studied and compared. The viscosity, ultraviolet (UV) transmittance, and thermal stability of the MFC samples at a certain concentration were determined. The results showed that the carboxyl content, water retention value, charge density, degree of polymerization, size distribution, and micromorphology of the pretreated and ground samples varied with those of the raw materials. The initial viscosity varied based on the type of raw material used. The MFC suspension prepared from cotton linter pulp had the highest UV transmittance, while the MFC prepared from bleached softwood kraft pulp had the highest viscosity at a low shear rate. After thermal degradation, the amount of residual char from the MFC prepared with the thermo-mechanical pulp was slightly higher than that of the other MFCs. This study demonstrates that carboxyethylation is an effective pretreatment method for different cellulosic materials.

Different Kinds of Microfibrillated Cellulose as Coating Layers Providing Fiber-based Barrier Properties

Zhang Ruijuan,Su Yanqun,Liu Jingang — 2021/1/25 11:31:48

In this study, we investigated the barrier properties of different kinds of microfibrillated cellulose (MFC) coating layers. The air, oxygen, and water vapor permeability, as well as the water contact angles (WCA), were measured to quantify the barrier efficacy of the applied coatings. The WCA data showed that the surfaces of MFC-coated cardboards are more hydrophilic than those of uncoated cardboards. However, different MFC coatings realize different oxygen transmission rates (OTRs) and water vapor transmission rates (WVTRs). The MFC coating derived from bleached bamboo pulp subjected to carboxyethylation pretreatment (MFC_CBP) gave the best oxygen and water vapor barrier performances. The OTR of the virgin cardboard (>16500 cm³/(m²·24 h)) decreased to 4638 cm³/(m²·24 h) after coating with the MFC_CBP. The WVTR similarly decreased from 1016.7 g/(m²·24 h) to 603.2 g/(m²·24 h).

Preparation of Chitosan-based Microspheres for Rapid Hemostasis

Fang Yan,Li Peiyuan,Zhou Weikang — 2021/1/25 11:31:49

Rapid control of heavy hemorrhaging is critical to save the life of injured individuals. Herein, we developed a novel hemostat employing chitosan-based microspheres, which was prepared by sequential microemulsion of chitosan solution, sol-gel phase transition, and surface modification by 3,4-dihydroxyhydrocinnamic acid (HCA). HCA-modified chitosan microspheres (CSMS-HCA) displayed a porous structure, with a high specific surface area (~211.3 m²/g), accelerating their rapid absorption of blood and concentrating red cells and platelets. The CSMS-HCA exhibited much better in vitro and in vivo hemostatic efficacy than porous chitosan microspheres did. Such a rapid hemostat in the form of microspheres is highly effective in treating deep and irregular wounds, owing to easy accessibility to injured sites.

Adsorption of Cu²⁺ by Crosslinked Graft Copolymers of Starch

Cai Xue,Lin Tao,Zhang Neng,Wei Xiaoyao,Yin Xuefeng — 2021/1/25 11:31:51

With the use of acrylic acid (AA) as a monomer, humic acid (HA) and starch as raw materials, potassium persulfate (KPS) as initiator, and N,N-dimethylacrylamide (MBA) as a cross-linking agent, AA/HA/Starch graft copolymer was prepared and characterized by SEM and FT-IR. The effects of temperature, adsorption time, adsorbent dosage, pH value and Cu²⁺ initial concentration of the solution on the adsorption performance of the crosslinked graft copolymer were also investigated. The results showed that the Cu²⁺ adsorption capacity of the AA/HA/Starch graft copolymer increased firstly and then decreased with increasing adsorbent dosage and the initial pH value of Cu²⁺ solution. With the increase of Cu²⁺ initial concentration and the extension of adsorption time, the adsorption amount of Cu²⁺ increased rapidly and then stabilized. And it decreased slightly with the increase of temperature. At pH value of 5.5, temperature of 298 K, adsorbent dosage of 50 mg, adsorption time of 125 min, and 100 mL Cu²⁺ solution with Cu²⁺ initial concentration of 100 mg/L, the Cu²⁺ adsorption capacity of the crosslinked graft copolymer was 238 mg/g. The adsorption of Cu²⁺ by the adsorbent followed the pseudo-second-order kinetic equation and Langmuir isothermal adsorption model, and the adsorption was attached to monolayer chemical adsorption. This study proved that AA/HA/Starch graft copolymer could be used as an efficient adsorbent for the removal of harmful and toxic metal cations such as Cu²⁺ from industrial wastewater.

Preliminary Study on the Reinforcing Effect of Nanocellulose on Supercapacitor Membranes

2022/10/20 14:34:15

In this study, six types of nanocellulose, as paper strengthening agents, were investigated for their reinforcing effects on a supercapacitor membrane by adding them to a slurry. The results indicated that adding 3% nanocellulose bacterial cellulose (BC)-B could effectively increase the tensile strength of the supercapacitor membrane by 36.5% without changing the pore structure of the membrane. Scanning electron microscopy images revealed that adding polyacrylamide to the supercapacitor membrane caused serious adhesion between fibers and affected the pore structure of the supercapacitor membrane, whereas adding BC-B did not produce similar effects.

Research State of Disposable Non-plastic Straws

Yuting Zhang,Ying Wan,Wen Liu — 2022/10/20 14:34:18

The continuous production of disposable plastic straw places a high demand on global petrochemical resources and a significant environmental burden. Biodegradable and eco-friendly straws have therefore been studied and produced worldwide. This article briefly introduces the characteristics of paper straws and polylactic acid (PLA) straws, and focuses on edible straws made using, e.g., hydrophilic colloids, zein, and starch. Raw-material selection, preparation methods, advantages, and defects of straws are summarized, to provide a reference for the development and research of eco-friendly straws.

Technical Evaluation of Hybrid Clones of Corymbia spp. to Produce Market Pulp

2022/7/20 14:26:05

This study presents hybrid clones of Corymbia spp. developed by Aperam BioEnergia as potential substitutes for Eucalyptus wood in the pulp industry. The biomass of Eucalyptus spp. was compared with that of Corymbia spp. by performing modified kraft pulping and basic density analyses. Comparisons were made by analyzing their respective mean annual increments of cellulose (MAI_cel) and specific wood consumption (SWC), estimated using a kappa number of (19 ± 1). The results showed that one of the hybrid clones (Corymbia citriodora × Corymbia torelliana, ID 4) had higher basic wood density, higher screened yield, better MAI_cel#k19, and lower SWC than the other samples, reaching values of 0.608 t/m³, 54.1%, 24.6 ADt/ha/year (i.e., air dry ton/hectare/year), and 2.74 m³/ADt, respectively. Consequently, clone ID 4 had the highest MAI_cel/SWC ratio score (8.98). Given its high forest productivity and low industrial cost compared with other samples, as well as its advantages over Eucalyptus spp. wood, we concluded that clone ID 4 has great potential as an alternative biomass for pulp production.

Stabilizing Pickering Emulsions Using Octenyl Succinic Anhydride Modified with Cellulose Nanofibrils

Jialei Qu,Langman Luo,Weifeng Zhang,Shao Geng,Chunping Wang,An Wang,Yangbing Wen — 2022/7/20 14:26:01

In this study, (2,?2,?6,?6-tetramethylpiperidin-1-yl)oxyl-mediated (TEMPO-mediated) oxidized cellulose nanofibrils (TOCNFs) modified with octenyl succinic anhydride (OSA) to improve their hydrophobicity and emulsification performance were investigated. OSA loadings of 9.87-14.81 mmol/g (base on oven-dry weight of TOCNFs) were explored during modification, and the obtained OSA-modified TOCNFs (TOCNF-OSA) were characterized using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and thermogravimetric analysis. Additionally, the emulsification performance of TOCNF-OSA was also investigated in the preparation of the Pickering emulsion. The results demonstrated that the molecular chain of OSA was successfully grafted onto the backbone of TOCNFs during modification. With an increase in OSA loading, the content of the carboxyl group of the modified TOCNF-OSA increased significantly while the Zeta potential decreased. Moreover, a degree of substitution of 0.95 could be achieved at an OSA loading of 14.81 mmol/g. During the preparation of Pickering emulsions, compared with original TOCNFs, the modified TOCNF-OSA significantly improved the stability and dispersibility of the Pickering emulsion. This study demonstrated a promising approach for the modification of the Pickering emulsion to produce an eco-friendly emulsifier with superior performance for use in the food industry.

Formation and Collapse of Cellulose Nanocrystals and Hydrophobic Association-induced Dual Cross-linked Nanocomposite Hydrogels: A Rheological Study

Xiaorui Jin,Mingguo Ma,Jun Yang — 2022/7/20 14:26:08

The rheological characteristics of a physical gelation system, in which cellulose nanocrystals (CNCs) induced the entanglement of poly(acrylic acid) (PAA) chains and partial hydrophobic association of octylphenol polyoxyethylene acrylate (OP-10-AC) branches in a micellar solution of sodium dodecyl sulfate (SDS), were investigated. The gelation time of the physical gels decreased as the CNC content and number of hydrophobic branch units increased. At the gel point, the storage modulus (G') and loss modulus (G") followed the same frequency dependence (G' ≈ G" ≈ ωⁿ), where the hydrophobic moieties attached to the side chains had a significant impact on the values of viscoelastic exponent (n). Beyond the gel point, the initial polymer solution was transformed to a solid-like gel, and the strength of the gel network was governed by associations between both the CNCs and hydrophobic groups. The evolution of the viscoelasticity during the gel-sol transition was monitored, demonstrating that due to a reversible arrangement of the hydrophobic units, a large proportion of physical cross-links dissociated under a thermal trigger and were reversibly reformed when the solution was cooled, while no such partial recovery was observed in the case of the single CNC-induced network systems (with no hydrophobic branches).

NIR-responsive Collagen-based Sponge Coated with Polydimethylsiloxane/Candle Soot for Oil-Water Separation

2022/7/20 14:26:08

To fabricate an oil-water separation material that is rich in source, eco-friendly, and responsive, in this study, we successfully developed a collagen-based sponge for application to oil-water separation based on a green and facile strategy. In this design, widely-available collagen (COL) was used as the substrate: it was immersed in polydimethylsiloxane (PDMS) suspension with candle soot (CS) nanoparticles, followed by hot curing. The resultant sponge (CS/PDMS-COL) possessed good hydrophobicity with a water contact angle of 148.3° under a low PDMS concentration of 2%. The results from field emission scanning electron microscope, Fourier transform infrared spectrometer, X-ray photoelectron spectrometer, and X-ray diffractometry demonstrated the successful coating of CS and PDMS on the surface of COL substrate. The CS/PDMS-COL can adsorb eight oils, with the adsorption capacity for trichloromethane reaching 95 g/g. With benzene as the target adsorbent, the separation efficiency was maintained at no less than 95% even after recycling 20 times. CS/PDMS-COL was also used to separate oil-in-water emulsion. Moreover, the sponge killed bacteria effectively due to its excellent near-infrared photothermal responsiveness. This study provides new insight into the preparation of facile oil-water separation materials based on naturally occurring biomaterials effortlessly.

Octadecylamine Graft-modified Cellulose Nanofiber and Its Reinforcement to Poly(butylene adipate-co-terephthalate) Composites

Leilei Hou,Jinghuan Chen,Jingang Liu — 2022/7/20 14:26:06

Biodegradable polymers such as poly(butylene adipate-co-terephthalate) (PBAT) have attracted great interest as alternatives to traditional petroleum-based polymers. Nonetheless, it is necessary to improve some properties of PBAT, such as mechanical strength. Cellulose nanofiber (CNF) can improve PBAT mechanical strength, but its dispersion and compatibility in the PBAT matrix require further improvement. In this study, octadecylamine (ODA) was utilized to graft-modify CNF to change the fiber-to-fiber interaction and improve its compatibility with the PBAT matrix. PBAT composites with 1 wt% CNF were prepared using a masterbatch premixing method to avoid CNF aggregation during extrusion. The effects of ODA graft modification on CNF properties were studied; varying degrees of CNF modification were investigated for their effect on PBAT properties. ODA-modified CNF (OCNF)/PBAT melt-extruded composites possessing 17.2% higher tensile strength than pure PBAT polymer were obtained without affecting the thermal stability of PBAT. As a result, surface modification of CNF with ODA is an effective strategy for improving CNF-PBAT compatibility.

Review of Carbon Dots from Lignin: Preparing, Tuning, and Applying

2022/7/20 14:26:04

Carbon dots (CDs), emerging carbon materials with unique physical and chemical properties, have drawn extensive attention from researchers. In recent years, many carbon sources have been used as precursors for preparing CDs. In contrast to other types of precursors, lignin, as a renewable and available source of natural aromatic biopolymers, is believed to be a low-cost precursor for the large-scale preparation of CDs. However, the preparation of CDs with excellent optical properties from lignin has some drawbacks because of the complex structure of lignin. Hence, the methods for preparing the CDs from lignin are summarized in this paper, and the mechanism and physical and chemical properties of lignin-based CDs are discussed. Moreover, some approaches to tuning the optical properties of lignin-based CDs have been proposed. Additionally, the use of lignin-based CDs in the fields of sensing, supercapacitor, bioimaging, anti-counterfeiting, and information encryption is reviewed.

Nanocomposite Hydrogel Materials for Defective Cartilage Repair and Its Mechanical Tribological Behavior—A Review

Prem Sagar,Amit Handa,Gitesh Kumar,Vikas Gupta,Rinku Walia,Shivali Singla — 2022/7/20 14:26:01

Osteoarthritis (OA) is a regressive ailment that affects a large population of patients. The most common symptoms of OA in humans are cartilage abnormalities. Hydrogels are excellent candidates for cartilage regeneration and are widely accepted as implants. In the past few decades, numerous types of hydrogels have been synthesized to repair cartilage defects. This study highlights recent advances in hydrogel development for the treatment of cartilage defects. In addition, the detailed progression of tailored nanocomposite hydrogels is summarized, and emphasis has been placed on the mechanical properties, especially the tribological behavior of the developed nanocomposite hydrogels.

Performance Assessment of Nanocellulose Hydroxypropyl Methyl Cellulose Composite on Role of Nano-CaCO₃ for the Preservation of Paper Documents

Xiaochun Ma,Altaf Halim,Xiaohong Li,Huiming Fan,Shiyu Fu — 2022/4/27 16:21:13

Deacidification and self-cleaning are important for the preservation of paper documents. In this study, nano-CaCO₃ was used as a deacidification agent and stabilized by nanocellulose (CNC) and hydroxypropyl methylcellulose (HPMC) to form a uniform dispersion. Followed by polydimethylsiloxane (PDMS) treatment and chemical vapor deposition (CVD) of methyltrimethoxysilane (MTMS), a hydrophobic coating was constructed for self-cleaning purposes. The pH value of the treated paper was approximately 8.20, and the static contact angle was as high as 152.29°. Compared to the untreated paper, the tensile strength of the treated paper increased by 12.6%. This treatment method endows the paper with a good deacidification effect and self-cleaning property, which are beneficial for its long-term preservation.

Enhanced Redispersibility of Cellulose Nanocrystals in Water via Surface Adsorption of Hydrolyzed Sugars from Corresponding Cellulose Nanocrystal Fabrication

2022/4/27 16:21:18

Generally, hydrogen bonds are formed between cellulose nanocrystals (CNCs) during their water removal and drying, leading to the irreversible aggregation of CNCs, and thus a poor water-redispersibility. The present study demonstrated a novel approach that involved using hydrolyzed sugars generated from the corresponding CNC production as redispersing agents to enhance the redispersibility of CNCs. Experimental data indicated that hydrolyzed sugars can be adsorbed onto CNCs through ethanol precipitation. The oven-dried CNCs onto which hydrolyzed sugars were adsorbed via ethanol precipitation were homogeneously redispersed in water. The redispersed CNCs showed the particle size distribution, Zeta potential, and thermal decomposition properties similar to those of the CNCs without drying. This method may improve the use of hydrolyzed sugars obtained in the hydrolysate from the corresponding CNC production, as well as facilitate the transportation and storage of CNCs.

An Alternative Strategy to Obtain Cellulose Nanofibrils from Parenchyma Cellulose of Bagasse Pith and the Performance of Its Nanopaper

Tian Tan,Xiaoning Tang,Heng Zhang,Xin Gao — 2022/4/27 16:21:14

Cellulose nanofibrils (CNFs) were obtained through one-step mechano-partial dissolution by ball milling in N, N-dimethyl acetamide with a low concentration of LiCl from agricultural waste bagasse pith (BP). Compared with fibrous cellulose, parenchyma cellulose (PC) is less uniform in diameter and less aligned, causing PC to dissociate into CNFs during this process without pretreatment. The results showed that the CNFs prepared from PC of BP had a diameter of 30-200 nm and a length of several micrometers. The as-obtained CNFs, along with dissolved cellulose, formed a wet-stable and highly transparent nanopaper in a sorbitol aqueous solution bath, which exhibited a high strain of 101% and a low Young's modulus of 4.3 MPa owing to the addition of the plasticizer sorbitol. This type of nanopaper with favorable transparency, high tensile property, and low Young's modulus has great potential for use as electronic skin and medical dressing material.

Preparation and Characterization of Co₃O₄/Graphene/Cellulose Nanofiber Composite Films

Zejun Ding,Tianying Chen,Yiming Zhou,Peng Zhu,Feiyun Li,Yanjun Tang — 2022/4/27 16:21:11

Nanocellulose has served as an eye-catching nanomaterial for constructing advanced functional devices with renewability, light weight, flexibility, and environmental friendliness. In this study, Co₃O₄/graphene/cellulose nanofiber (CNF) flexible composite films, in which the CNF acted as a spacer for the graphene, were prepared via a facile and scalable vacuum filtration method. The effects of the CNF on the microstructure, hydrophilicity, thermal stability, tensile strength, surface resistance, and electrochemical performance of the Co₃O₄/graphene/CNF composite films were systematically investigated. The results showed that the synergistic interaction of the CNF and graphene substantially improved the overall properties of the Co₃O₄/graphene/CNF composite films, particularly their hydrophilicity and tensile strength. Meanwhile, Co₃O₄/graphene/CNF composite films with a CNF content of 4% appeared to have the optimal electrochemical performance, with an area specific capacitance of 56 mF/cm² and prominent capacitance retention of 95.6% at a current density of 1 A/g after 1000 cycles. This work demonstrated that the prepared Co₃O₄/graphene/CNF flexible composite films have great application potential in the field of flexible energy storage devices.

Lignin-containing Microfibrillated Cellulose Prepared from Corncob Residue via Calcium Hydroxide Co-grinding and Its Application in Paper Reinforcement

Jinghuan Chen,Jingang Liu,Zehong Xu — 2022/4/27 16:21:10

In this study, lignin-containing microfibrillated cellulose (MFC) was prepared from corncob residue after xylose extraction via co-grinding with calcium hydroxide. The product was then compared with the MFC obtained by direct grinding and applied to strengthen paper. The chemical composition and morphological structure analysis results showed that the corncob residue can be used to prepare lignin-containing MFC and does not require further purification. Moreover, the co-grinding with calcium hydroxide is easier to fibrillate corncob residue. The MFC obtained by co-grinding with calcium hydroxide had a higher aspect ratio, and its surface was coated with calcium carbonate nanoparticles. MFCs obtained by both the methods mentioned above had an obvious strengthening effect on paper. Compared with the paper without MFC, the tensile index, elongation, burst index, and folding strength of the paper with MFC obtained by co-grinding with calcium hydroxide significantly increased by 17.5%, 22.1%, 19.5%, and 157.1%, respectively. This study provides a novel idea for the utilization of corncob residue, which may enhance the value and promote the comprehensive utilization of corn by-products.

Okara Cellulose Nanofibrils Produced by Pretreatment with Sustainable Deep Eutectic Solvent Coupled with Various Mechanical Treatments

2022/4/27 16:21:17

In this study, a green, environmentally friendly method for rapid cellulose nanofribril (CNF) preparation with a significant cost advantage was developed. Pretreatment with a deep eutectic solvent (DES) synthesized from oxalic acid dihydrate and choline chloride (ChCl-O) was combined with various mechanical treatment methods to produce okara CNFs from agricultural waste, with different diameter distributions. The results showed that high-speed stirring produced CNFs with an average diameter of 27 nm. This method was advantageous because it consumed about 94% less energy than traditional high-pressure homogenization method. The DES recovery rate was more than 90%, and DES served as a highly effective treatment, indicating that DES pretreatment is an economical, convenient, and effective strategy for okara CNF preparation.

Magnetic Wood-based Superhydrophobic Aerogel for Efficient Oil-Water Separation

Junqing Chen,Zede Yi,Shiyu Fu — 2022/4/27 16:21:15

The fabrication of directionally driven oil-water separation materials has great significance for the removal of oil spills and organic pollutants. In this study, an oil-water separation aerogel capable of directionally adsorbing oil was designed using an anisotropic wood aerogel with a layered structure and a top-down fabrication strategy. Specifically, a magnetic wood-based superhydrophobic aerogel (methyltrimethoxysilane (MTMS)/Fe₃O₄ wood aerogel) was developed through the in situ co-precipitation of Fe₃O₄ nanoparticles and chemical vapor deposition. Owing to its highly porous structure, lipophilicity, hydrophobicity (water contact angle of 160°), and high compressibility, the MTMS/Fe₃O₄ wood aerogel exhibits excellent oil-water separation performance and compression cycle stability. Additionally, the Fe₃O₄ endows the material with excellent magnetic and photothermal conversion capabilities. These excellent properties make MTMS/Fe₃O₄ wood aerogel a promising recyclable and sustainable oil-water separation material.

Physicochemical and Morphological Variation of Bamboo Cell Wall During Hydrothermal Pretreatment

Xiaojuan Yu,Kai Fan,Xi Yao,Meng Wang,Kun Wang — 2022/1/20 11:23:08

Pretreatment is important for achieving high-value utilization of biomass. This study is conducted to evaluate the destruction of the Moso bamboo cell wall via hydrothermal pretreatment at different temperatures and pH values. Compositional and morphological analyses and subsequent enzymatic hydrolysis of the solid fractions indicate that the destruction of the cell wall, instead of the degradation or removal of hemicellulose and lignin, or the configuration transition of the cellulose crystal structure, is the most critical aspect for improving bioconversion efficiency. Although only an 8%-10% weight loss is incurred and similar crystalline indexes are achieved after mild hydrothermal treatments, the recovery of glucose is doubled, whereas the recovery of xylose from pretreated samples is approximately 35%.

Preparation and Functional Design of Polyethyleneimine Reinforced Nanocellulose-based Aerogel

Jiacheng Lin,Tao Lin,Xuefeng Yin,Xue Cai,Xiaoyao Wei,Neng Zhang — 2022/1/20 11:23:12

An aerogel electrode composed of conductive active materials based on nanocellulose aerogels can absorb more electrolytes, as well as enhance electron transport and ion diffusion channels. In the present study, aerogels with high strength were successfully prepared using 2,2,6,6-tetramethyl-1-piperidinyloxy free radical (TEMPO)-oxidized cellulose nanofibrils (CNF) as a raw material and polyethyleneimine (PEI) as a cross-linking agent. Simultaneously, functional electrode materials were prepared via self-assembly. Based on our findings, PEI can significantly improve the water and solvent solubility and enhance the wet strength and shape recovery ability of CNF aerogels. Meanwhile, the minimum density of the aerogel reached 0.0160 g/cm³, the maximum porosity was approximately 98.5%, and the maximum stress approximated 0.02 MPa. Furthermore, electrochemical tests revealed that after self-assembly of reduced graphene oxide (RGO) and polyaniline (PANI) solution, the mass specific capacitance of the functional composite aerogel was approximately 92 F/g and exhibited good charge-discharge performance.

Facile Approach for Preparation of Xylan-based Double-network Hydrogels

Ziwen Lyu,Jun Rao,Xianming Qi,Ziyi Bai,Siyu Jia,Zhenhua Su,Feng Peng — 2022/1/20 11:23:09

In this study, xylan-based double-network (DN) hydrogels (xylan-based DN gels) with excellent mechanical properties were prepared using acrylic acid and acrylamide (AM) based on a DN approach. The first layer network was obtained by grafting and crosslinking polyacrylic acid (PAA) molecular chains onto xylan with ammonium persulfate (APS) as the initiator and N,N'-methylenebisacrylamide (MBA) as the crosslinking agent; this network was subsequently immersed into an aqueous AM monomer in the presence of APS and MBA for the preparation of the second layer network. The results showed that the double networks were crosslinked by covalent bonds and that the mechanical properties of the xylan-based DN gels were enhanced. Thus, the xylan-based DN gels exhibited a maximum compression stress of 24.9 MPa. The xylan-based DN gels could also recover 97% of their original height after 15 repeated compression cycles; this indicates that the xylan-based DN gels possessed high resistance to friction and wear. Therefore, the prepared xylan-based DN gels have considerable potential for tissue engineering applications.

Dispersive Ability of Carboxylated Cellulose Nanofibrils for Aqueous Monolayer Montmorillonite Dispersion: Influence of Na⁺ and Ca²⁺ Concentrations

Kaihuang Chen,Chuan Sun,Guanhui Li,Jinhao Huang,Zhiqiang Fang,Xueqing Qiu — 2022/1/20 11:23:15

Carboxylated cellulose nanofibrils (CNFs) have emerged as effective green dispersants for monolayer montmorillonite (MMT) dispersions. However, their dispersion capability is sensitive to the metal ion concentration in aqueous solutions. Hence, this study investigated the effects of Na⁺ and Ca²⁺ concentrations on the dispersive ability of carboxylated CNFs for monolayer MMTs in water. Quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM) were utilized to explore the interfacial interactions between the carboxylated CNFs and monolayer MMTs under different Na⁺ and Ca²⁺ concentrations. When the concentration of Na⁺ reached 0.1 mmol/L, the adhesion mass of carboxylated CNFs on MMT-coated wafer peaked at 24.47 mg/m², higher than control sample (carboxylated CNF-dispersed monolayer MMT dispersion without metal ions, 16.03 mg/m²). Moreover, the electrostatic shielding effect promoted a better dispersion of monolayer MMTs by carboxylated CNF dispersant. With a further increase in the Na⁺ concentration, the surface charge of CNFs and MMTs would be reversed resulting from the improved electrostatic shielding effect, which weaken the dispersive ability of carboxylated CNFs. The addition of Ca²⁺ reduced the dispersive ability of carboxylated CNFs for monolayer MMTs, because Ca²⁺ required a lower concentration for the onset of charge reversal compared to Na⁺. This study provides interfacial scale insights into the influence of metal ion concentration on carboxylated CNF-dispersed monolayer MMT dispersions. It also provides a strategy to enhance the dispersive ability of carboxylated CNFs for monolayer MMTs.

Improving the Surface Performance of Electrospun Air Filter Paper Using Multi-walled Carbon Nanotubes

Weiyin Su,Lanfeng Hui,Yang Gao,Mingyue Zhao — 2022/1/20 11:23:15

In this study, air filter base paper (P) was used as the receiving substrate, polyvinyl alcohol (PVA) and PVA/multi-walled carbon nanotube (MWCNT) spinning solutions were used to prepare electrospun air filter papers (P-PVA and P-PVA/MWCNT, respectively). Then, P-PVA/MWCNT was calendered under different pressures. The effect of MWCNTs on the surface performance of P-PVA/MWCNT was explored and the influence of calendering technology on their structure and filtration characteristics was analyzed. Electron scanning microscope observation showed that the PVA nanofibers on the surface of P-PVA/MWCNT had no beading, and MWCNTs weakened the surface electrostatic phenomenon and had a good micromorphology. During the calendering process, with an increase in pressure, the mean pore size and surface roughness of P-PVA/MWCNT decreased, the initial resistance increased, and the filtration efficiency changed slightly.

Comparison of Nanofibrillated Cellulose and Hydroxyethyl Cellulose in Improving the Storage Stability of Waterborne Coatings

Xinqi Li,Jinghuan Chen,Jingang Liu,Tao Zhao,Kaiji Yang — 2024/1/9 8:55:18

Waterborne coatings often delaminate and settle during long-term storage, requiring the addition of thickeners. The effects of nanofibrillated cellulose (NFC) and the commonly used thickener, hydroxyethyl cellulose (HEC), on the storage stability of waterborne coatings were compared in this study. The morphology of NFC was characterized using infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The rotational viscosity and rheological properties of the waterborne coatings with NFC and HEC were tested. Stationary settling experiments were also conducted at different temperatures to compare the difference of NFC and HEC on improving the storage stability of the waterborne coatings. The results showed that the waterborne coating with NFC exhibited pseudoplastic fluid characteristics; a small addition of NFC can achieve the same improvement effect on the storage stability of waterborne coatings as HEC. Further, the improvement effect of NFC was not affected by temperature. The waterborne coating with NFC still exhibited good storage stability at high temperatures, which was significantly superior to that of HEC. Therefore, NFC is a feasible agent for improving the prolonged storage stability and warming-induced delamination of waterborne coatings.

Green Superhydrophobic Paper with Self-cleaning Properties Prepared via One-step Impregnation

2024/1/9 8:55:20

In this study, a green and pollution-free multifunctional superhydrophobic paper-based material was prepared using a simple and efficient dipping method. The superhydrophobic paper with a water contact angle (WCA) of 160° was prepared by attaching micro- and nanocomposite particles, made of stearic acid-modified chitosan and two kinds of titanium dioxide (TiO₂) nanoparticles of different sizes, to a paper substrate. The surface morphology, elemental composition, and wetting properties of the coatings were examined using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), and contact angle measurements. Additionally, superhydrophobic coatings exhibited good self-cleaning properties, liquid repellency, ease of repair, and antifouling properties in organic solutions.

Degradable Foam Tray Based on High-concentration Dispersed Cellulose Fibers Obtained by a Hot-press Baking Process

2024/1/9 8:55:22

Degradable industrial packaging foam trays made from cellulose fibers were fabricated using a hot-press baking process. Bleached softwood pulp fibers with a concentration of 30% were dispersed at a high speed under the action of a dispersant. The effects of the dispersant dosage of the fibers on the porosity, foam density, and static compression characteristics were discussed. Furthermore, the effects of the reinforcing adhesive including polyvinyl alcohol (PVA), and cassava starch on the physical and mechanical properties of the foam trays were studied, as well as the relationship between these properties and the microstructure of the foam trays. The dispersant enhanced the rheological and blistering properties of the fiber dispersion. As the dispersant dosage increased from 2% to 4%, the foam density gradually increased and the compressive strain performance and residual compressive strain of the foam trays decreased. Under the condition of constant dosage of dispersant, increasing the fiber proportion from 67% to 77% improved the porosity and foam density and slightly reduced the static compression performance. In additioton, the static compression resistance of the foamed materials was improved by increasing the PVA dosage since PVA was beneficial for improving the strength of the foam trays.

Effect of Refiner Plate Bar Angle and Pulp Properties on the Low Consistency Refining Efficiency in Terms of Power Consumption

Huan Liu,Jixian Dong,Yongping Pu,Xiya Guo,Lijie Qiao,Yan Yan — 2024/1/9 8:55:24

Power consumption is the energy source of the impact on fibers or pulp during low-consistency (LC) pulp refining, and the strength of refining affects refining quality and efficiency. The pulp properties, operating parameters, and bar parameters of the refiner plates are important parameters affecting refining efficiency, which can be defined as the ratio of net to total refining power. In this study, LC refining trials for pulps with different consistencies and fiber lengths were conducted using five isometric straight-bar plates with different bar angles to explore the influences of the plate bar angle and pulp properties on the no-load power, impact capacity on fibers and refining efficiency. It was found that the no-load power of the LC refining process decreased with an increase in the plate bar angle while increased when pulp with higher consistency was refined under the same refining conditions. However, the effect of pulp consistency on the no-load power can be neglected when refining is conducted using plates with larger bar angles. Meanwhile, a critical bar angle for straight-bar plates in LC refining may exist, which has the strongest impact on the pulp and highest refining efficiency under the same refining conditions. In addition, the impact capacity of the plate on the pulp and refining efficiency in LC refining can be enhanced by appropriately increasing the pulp consistency and average fiber length when the bar angle of the refiner plate with a sector angle of 40° is less than 30°. Therefore, the efficiency and power consumption of the LC refining process can be adjusted by optimizing the pulp consistency and bar parameters of the refining plates.

Identification of 13th-14th Century Chinese Handmade Paper Fibers Collected in Yuan Dynasty Paper Currencies

Xingxing Liu,Danjiancuo Yuan,Qiulin Han,Jiali Chen — 2024/1/9 8:55:25

The earliest paper currencies in existence in China were handcrafted during the Yuan dynasty. These currencies were scientifically excavated from different ruins or tombs, whereas scientific analyses of the papers are rare. This study used optical and scanning electron microscopy to examine the fibers collected in Yuan dynasty paper currencies in conjunction with the Herzberg staining method. Despite differences in circulation period, paper fibers in both Zhi Yuan Tong Xing Bao Chao (two Guan) and Zhong Tong Yuan Bao Jiao Chao (one Guan and 500 Wen, issued in Zhi Zheng period) were identified as similar papermaking materials, bast fibers of mulberry bark. The results indicate that mulberry bark, a durable papermaking material used since ancient times, was mainly utilized as a raw material in these Yuan dynasty paper currency. This fiber identification work solved the critical problem of papermaking material in the Yuan dynasty paper currency and provided important information for conserving these precious cultural relics.

Aging Resistance Evaluation of Aged Paper Reinforced with Different Nanocelluloses

2023/7/17 16:51:56

Paper documents experience severe acidification and embrittlement. Nanocellulose is an excellent reinforcement material for paper documents owing to its compatibility and excellent mechanical strength. However, little research has been conducted on the aging resistance of nanocellulose-reinforced paper. In this study, six types of nanocelluloses were used to reinforce aged paper. The reinforcement and anti-aging performances were evaluated, and the anti-aging mechanism was further clarified. Nanocellulose with a high degree of polymerization can better enhance aged paper, and non-chemical nanocellulose also shows better anti-aging performance, such as nanocellulose prepared by mechanical or biological methods. However, nanocellulose prepared using chemical methods exhibits poor reinforcement and anti-aging performance. This is because it has a small particle size that is not beneficial for physical crosslinking with paper fibers. More importantly, the introduction of acidic or oxidizing groups on nanocellulose accelerates the acid hydrolysis and oxidation rate of paper fibers, especially nanocellulose prepared by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation, which should not be used to protect paper documents.

Comparative Study on the Physical Properties of Edgeworthia and Wikstroemia Handmade Paper

Ruxuan Zhao,Gang Chen — 2023/7/17 16:51:57

Both Edgeworthia and Wikstroemia have been used traditionally in hand papermaking in China. As plants from the Thymelaeaceae family, these species have been mentioned periodically and have been mixed or substituted with each other. This study reviewed their papermaking background and status, and selected one of the Edgeworthia and three of the Wikstroemia raw materials that are still in use. Pulp was cooked under the same conditions in the laboratory, and handsheets of pure and mixed materials were obtained using a Rapid-K?then sheet former. A series of physical properties, such as color, structure, and mechanical properties were tested, followed by a comparison and discussion of the raw material properties. The results show that Wikstroemia fibers are generally thinner and shorter, but there are variations between the different genera of raw materials. Thus, compared with Edgeworthia, Wikstroemia has some advantages in tensile strength, although it shows some disadvantages when it comes to tearing strength. The performance of a mixed-ingredient paper sheet falls between the performance of two pure-component papers. For cost and performance reasons, adding a small amount of Wikstroemia (e.g., <20%) to Edgeworthia is preferable.

Physical Condition of Five Historical Land Deeds and Implications for Land Deed Paper Conservation

Xue Li,Guanghui Yang — 2023/7/17 16:51:57

This work presents five land deeds (S1-S5) collected by the Deng family, the land deed papers were produced by the Deng family, and the content was about the transaction of the Deng family paper production site. Density, whiteness, pH value, and fiber morphology of the deed papers were measured and analyzed, and the physical condition of the deeds was determined. The results showed S1 and S3 were severely damaged, S2 and S4 were moderately damaged, and S5 was mildly damaged. The abovementioned deeds are physical witnesses to the history of Deng papermaking, and have high value as cultural relics and historical documents. It is hopefully this study could be used to inform scientific restoration plans, and provide a reference for the collection and protection of land deeds.

Techniques of Wallpaper (Biao Hu) in the Palace Museum: A Case Study of the Lodge of Bamboo Fragrance (Zhuxiang Guan)

Yue Ma — 2023/7/17 16:51:58

Biao Hu was one of the eight famous traditional crafts in the late Qing dynasty. This skill involved decorating the interiors of ancient buildings such as ceilings, walls, and windows and creating burial objects. It was primarily used for wooden buildings in northern China during the early Qing dynasty. For example, there is white-patterned wallpaper in the Forbidden City utilizing both traditional and nontraditional patterns. Moreover, there was wallpaper with a special pattern in the Lodge of the Bamboo Fragrance (Zhuxiang Guan). Its structure and composition were studied via morphological observations and spectral analyses, the pigments and dyes were analyzed by Raman spectroscopy and ultra-high performance liquid chromatography-mass spectrum (UPLC-MS). Traditional technology and exchanges between China and the West were discussed by the study of patterned wallpapers in other buildings of the Forbidden City.

Oxygen-doped Carbon Nitride Nanocages with Efficient Photon-to-Electron Conversion for Selective Oxidation of Xylose/Xylan to Yield Xylonic Acid

2023/4/25 13:38:33

Highly efficient photon-to-electron conversion is crucial for achieving photocatalytic conversion. In this study, oxygen-doped carbon nitride nanocages (O@CNNCs) were engineered via dual strategies of morphology-controlled heteroatom doping, which was successfully used in the photocatalytic selective oxidation of xylose/xylan to xylonic acid. The nanocage-shaped O@CNNCs had a larger surface area, which was 4.02 times of carbon nitride (CN). Furthermore, with the assistance of morphology regulation and O-doping, O@CNNCs exhibit highly efficient photon-to-electron conversion, enhanced visible-light utilization, high photocurrent, low resistance, and fast separation/migration of electron-hole pairs. Correspondingly, the photocatalytic oxidation of xylose to xylonic acid using O@CNNCs was successfully achieved under mild reaction conditions with a yield of 83.4%. O@CNNCs have excellent recyclability, in which the yield of xylonic acid in the 5th cycle was 98.2% of its initial use. The O@CNNC photocatalytic system was also suitable for macromolecular xylan, and a xylonic acid yield of 77.34 mg was obtained when 100 mg xylan was used. The oxidation-active species captured experiments indicated that holes were crucial for the selective oxidation of xylose to xylonic acid. Overall, this study provides a new strategy for the preparation of photocatalysts with excellent photon-to-electron conversion and selective oxidation of biomass-derived feedstocks to xylonic acid.

High Performance of Paper Strength and Energy Savings in OCC Pulp Papermaking via MFC Addition

Hui Cai,Jiulong Sha,Changsheng Lu,Wenlun Qiu,Junjie Liu,Yang Liu — 2023/4/25 13:38:34

Fiber screen fractionation of recycled old corrugated container (OCC) pulp and subsequent targeted processing of each fraction can lead to higher fiber quality, more uniform pulp, and increased handsheet strength and surface smoothness. This pilot-scale study evaluates the benefits of fiber fractionation using a pressure screen prior to low consistency (LC) refining. A 0.81-mm smooth holed screen cylinder is utilized, and two refiner plate patterns are adopted (wide 0.99 km/rev BEL and interim 2.01 km/rev BEL). Here, LC-refined reject fractions are mixed with the created microfibrillated cellulose (MFC), and the mixed pulp and paper qualities are compared with no-MFC OCC pulps. The results indicate that the highest tensile strength of the handsheet is obtained by the addition of MFC to the fractionated refined OCC pulp compared to the unfractionated refined OCC and primary OCC pulps at a given specific energy. Furthermore, the experimental approach adopted in this study can be used to optimize recycled OCC pulping systems. Overall, the results indicate that fractionated LC refining plus MFC addition provides higher pulp and paper qualities and the potential for saving energy to reach the desired tensile strength of the OCC pulp.

Effects of Rice Straw Steam-explosion Spent Liquor on the Growth of Cabbage Seedlings

Bo Jiang,Huan Jiao,Xinyu Guo,Yu Zhang,Yanguang Zhang,Yongcan Jin — 2023/4/25 13:38:36

The direct use of spent liquor from pulping and papermaking engineering, which is abundant in active organic matter, can avoid resource wastage and environmental pollution. In this study, the effects of soaking solution and filtrate from steam-exploded rice straw on seed germination and the early development of cabbage were investigated. The results have shown that soaking solution and filtrate stimulated early cabbage growth at low concentrations. Optimal germination potential and the rate of soaking solution-treated cabbage seeds increased by 8% and 5%, respectively; meanwhile, that of the filtrate-treated cabbage seeds increased by 11% and 5%, respectively. Promotion of root growth by steam-exploded rice straw spent liquor was expressed in lateral root multiplication. The fresh weight of cabbage seedlings treated with the soaking solution/filtrate increased by more than 50% and the dry weight over 20%. Comparatively, the stimulation of filtrate on seed germination and early development of cabbage is superior to that of the soaking solution. Steam-exploded rice straw spent liquor is rich in bioactive lignin and oligosaccharides, which makes it a promising biostimulant for promoting crop growth.

Surface Modification of Bamboo-based Activated Carbon for Methylene Blue Removal

Derong Tang,Ruonan Zhao,Feiyun Li,Tianying Chen,Yanjun Tang — 2023/2/6 19:09:36

The feasibility of biomass-based activated carbon has received tremendous attention owing to its excellent properties, such as insensitivity, good adsorption performance, and potential to reduce the strong dependence on non-reproducible precursors. In this study, bamboo-based activated carbon (BAC) was used as the raw material for methylene blue (MB) removal. Cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and sodium dodecylbenzene sulfonate (SDBS) were used as BAC surface modifiers. The morphologies and structures of the samples were characterized. In addition, the effects of the surfactant type and concentration on the adsorption-based removal of MB from aqueous solutions by the modified BAC were systematically investigated. For the 0.2 g/L MB solution, the MB removal rate reached 99.7% when the concentration of CTAB was 0.25 g/L. Moreover, the kinetic model curve of 0.25 g/L CTAB-modified BAC (CAC) was consistent with the Freundlich isotherm model. This research work enriches the technical pathway of modification and application of activated carbon, which is not only beneficial for realizing the high-value utilization of biomass bamboo resources but also can play an active role in guiding the treatment of MB-containing wastewater.

Preparation and Characterization of Cellulose Nanofibril-Waterborne Polyurethane Composite Films

Xinqi Li,Jinghuan Chen,Jingang Liu,Qi Chen — 2023/2/6 19:09:37

To improve the performance of polyurethane films, small amounts of cellulose nanofibrils (CNF) were physically blended with a waterborne polyurethane (WPU) emulsion, and then CNF/WPU composite films were prepared by cast-coating and drying. The particle size of the emulsions and the chemical structure, micromorphology, thermal stability, mechanical properties, and water resistance of the composite films were characterized using a Malvern laser particle size analyzer, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), an electronic strength machine, water contact angle analysis (WCA), and water absorption tests, respectively. The results showed that at a low CNF content of 0.3 wt%, the particle size of the WPU emulsion and chemical structure of the film did not change significantly. In addition, the tensile strength of the composite film increased by up to 108% compared to the neat WPU film, and the thermal stability and water resistance were slightly improved. The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film, which may greatly improve the service life and tear resistance of commercial coatings in the future.

Novel Parameter Identification Method for Basis Weight Control Loop of Papermaking Process

Yunzhu Shen,Wei Tang,Yungang Liu — 2023/2/6 19:09:38

The basis weight control loop of the papermaking process is a non-linear system with time-delay and time-varying. It is impractical to identify a model that can restore the model of real papermaking process. Determining a more accurate identification model is very important for designing the controller of the control system and maintaining the stable operation of the papermaking process. In this study, a strange nonchaotic particle swarm optimization (SNPSO) algorithm is proposed to identify the models of real papermaking processes, and this identification ability is significantly enhanced compared with particle swarm optimization (PSO). First, random particles are initialized by strange nonchaotic sequences to obtain high-quality solutions. Furthermore, the weight of linear attenuation is replaced by strange nonchaotic sequence and the time-varying acceleration coefficients and a mutation rule with strange nonchaotic characteristics are utilized in SNPSO. The above strategies effectively improve the global and local search ability of particles and the ability to escape from local optimization. To illustrate the effectiveness of SNPSO, step response data are used to identify the models of real industrial processes. Compared with classical PSO, PSO with time-varying acceleration coefficients (PSO-TVAC) and modified particle swarm optimization (MPSO), the simulation results demonstrate that SNPSO has stronger identification ability, faster convergence speed, and better robustness.

Biodegradation Behavior of Starch in Simulated White Water System of Old Corrugated Cardboard Pulping Process

2023/2/6 19:09:40

Considering the serious barriers/issues induced by the accumulated starch generated in white water system of old corrugated cardboard (OCC) pulping process, large amounts of accumulated starch in white water would be decomposed by microorganisms and could not be utilized, thereby resulting in severe resource wastage and environmental pollution. This study mainly explored the effects of biodegradation/hydrolysis conditions of the two types of starch substrates (native starch and enzymatically (α?-amylase) hydrolyzed starch), which were treated via microorganism degradation within the simulated white water from OCC pulping system and their biodegradation products on the key properties were characterized via X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and gel permeation chromatography (GPC) technologies. The effects of system temperature, pH value, starch concentration, and biodegradation time on starch biodegradation ratio and the characteristics of obtained biodegradated products from the two types of starches were studied. In addition, the effect of α?-amylase dosage on the biodegradation ratio of enzymatically hydrolyzed starch and its properties was investigated. It was found that the native starch presented a maximal degradation ratio at a system temperature of 55 ℃ and pH value range of 5-7, respectively, the corresponding starch concentration within simulated white water system was 200 mg/L. Whereas the enzymatically hydrolyzed starch exhibited a highest degradation ratio at a system temperature of 50 ℃ and pH value of 5.5, respectively, and the corresponding starch concentration within simulated white water system was 100 mg/L. It was verified that native starch is more readily bio-hydrolyzed and biodegradation-susceptive by microorganisms in simulated white water system of OCC pulping process, while the enzymatically hydrolyzed starch exhibits better biodegradation/hydrolysis resistance to the microbial degradation than that of native starch. This study provides a practical and interesting approach to investigate the starch hydrolysis or biodegradation behaviors in white water system of OCC pulping process, which would greatly contribute to the full recycling and valorized application of starch as a versatile additive during paperboard production.

Identification and Control of Pitch in the Final Product of the Eucalyptus Pulp Production Line

2026/3/26 16:29:01

This study evaluated the agglomerating effect of aluminum on substances in weak black liquor from eucalyptus pulp washing, as well as its contribution to the formation of inorganic deposits. The addition of aluminum sulfate led to an increase in the levels of silica and magnesium, which were the major components of the resulting inorganic solids (termed "artificial pitch"). The artificial pitch closely resembled the historical deposits from a filtrate tank during normal operation (referred to as Event 1), thereby validating its suitability as a representative model. The deposits from Event 2, which occurred six years later, exhibited higher metal concentrations. This was attributed to delays in maintenance following a major earthquake. A parallel laboratory study was conducted to test the coagulant ECO 1024. It was found that this coagulant reduced the residual aluminum in mill water by 42%, and it was projected to result in annual savings of US$117,420. The results confirmed that aluminum played a role in promoting the agglomeration of silica and magnesium, which in turn contributed to the buildup of deposits, particularly under stable operating conditions. Moreover, ECO 1024 proved to be effective in mitigating the challenges associated with aluminum, offering both technical and economic advantages for optimizing pulp washing processes.