Paper and Biomaterials  2019,4(4):64-70

Cellulose-based Antimicrobial Composites and Applications: A Brief Review

Bo Sun, Fangong Kong, Min Zhang, Weijun Wang, Birat Singh KC, Jimi Tjong and Mohini Sain

2019,4(4):1-14

Cellulose-based antimicrobial composites, typically in the form of functional films and cloth, have received much attention in various applications, such as food, medical and textile industries. Cellulose is a natural polymer, and is highly biodegradable, green, and sustainable. Imparting antimicrobial properties to cellulose, will significantly enhance its applications so that its commercial value can be boosted. In this review paper, the use of cellulose for antimicrobial composites’ preparation was discussed. Two different approaches: surface loading/coating and interior embedding, were focused. Three most widely-applied sectors: food, medical and textile industries, were highlighted. Nanocellulose, as a leading-edge cellulose material, its unique application on the antimicrobial composites, was particularly discussed.

[Abstract] [PDF]

Lignin Interaction with Cellulase during Enzymatic Hydrolysis

Mingfu Li, Qingtong Zhang, Changzhou Chen, Shuangfei Wang and Douyong Min

2019,4(4):15-30

The conversion of lignocellulosic biomass into biofuels or biochemicals typically involves a pretreatment process followed by the enzyme-catalyzed hydrolysis of cellulose and hemicellulose components to fermentable sugars. Many factors can contribute to the recalcitrance of biomass, e.g., the lignin content and structure, crystallinity of cellulose, degree of fiber polymerization, and hemicellulose content, among others. However, nonproductive binding between cellulase and lignin is the factor with the greatest impact on enzymatic hydrolysis. To reduce the nonproductive adsorption of enzymes on lignin and improve the efficiency of enzymatic hydrolysis, this review comprehensively summarized the progress that has been made in understanding the interactions between lignin and enzymes. Firstly, the effects of pretreatment techniques on lignin content and enzymatic hydrolysis were reviewed. The effects of lignin content and functional groups on enzymatic hydrolysis were then summarized. Methods for the preparation and characterization of lignin films were assessed. Finally, the methods applied to characterize the interactions between lignin and cellulase were reviewed, and methods for decreasing the nonproductive binding of enzymes to lignin were discussed. This review provides an overview of the current understanding of how lignin hinders the enzymatic hydrolysis of lignocellulosic biomass, and provides a theoretical basis for the development of more economical and effective methods and additives to reduce the interaction of lignin and enzymes to improve the efficiency of enzymatic hydrolysis.

[Abstract] [PDF]

Reinforcing Paper Strength by Dual Treatment of a Cationic Water-soluble Polymer and Cellulose Nanofibril

Aijiao Wang, Lijun Wang, Jianmei Jiang, Xianping Yao and Wenyan Zhao

2019,4(4):31-36

Cellulose nanofibril (CNF) was used as the anionic component of two dual strengthening systems wherein polyamidopolyamine epichlorohydrin resin (PAE) or cationic starch (CS) was used as the cationic component. Their strengthening effects were investigated for low-basis-weight (30 g/m2) paper composed of a mixture of fully bleached softwood and hardwood pulp in a 4:1 mass ratio. Using the PAE/CNF or CS/CNF dual system, it was generally easier to achieve higher wet and dry tensile strengths of paper compared to the paper using the single PAE or CS system. For example, the paper using the PAE (0.4%)/CNF (0.3%) dual system exhibited 89% higher wet tensile strength than the paper using the single PAE (0.4%) system, and the paper using CS (1.3%)/CNF (0.3%) dual treatment showed 21% higher dry strength than that using the single CS (1.3%) system. However, the PAE/CNF system only showed small improvement in the dry strength of paper (11% higher than that of paper using the single PAE system), so did the CS/NFC system on wet strength improvement (only 17% higher than that of paper using the single CS system).

[Abstract] [PDF]

Effect of High Pressure Homogenization Treatment on Structure and Properties of Soybean Residue Cellulose Nanofibers

Peiyi Li, Yumeng Wang, Binyao Zhou, Qingqing Hou, Hezhen Liu, Haozhe Lei, Boxing Jian and Xinping Li

2019,4(4):37-44

To reduce the adverse effects of non-cellulose materials on subsequent homogenization, the effects of a high-pressure homogenization treatment on the structure and properties of cellulose nanofibers (CNF) prepared by acid treatment of soybean residue were studied. The effects of the number of homogenization step on the microfibrillation degree, crystalline structure and mechanical properties of the soybean residue were analyzed by SEM, FT-IR, XRD, TG and DTG. The results showed that an increase in the number of homogenization steps led to an increase in the degree of microfibrillation, a more uniform distribution of the CNF diameter, and an increase in the crystallinity of CNF. However, but when the number of homogenization steps exceeded 15, the rate of change decreased, and the crystallinity of CNF decreased. As the number of homogenization steps increased, the average degree of polymerization and average molecular weight of CNF decreased continuously, and after 15 homogenization steps, their rate of change also decreased. Therefore, 15 steps of high-pressure homogenization represented a suitable number of steps to prepare the soybean residue CNF with an average diameter of 15 nm.

[Abstract] [PDF]

Preparation and Adsorption Properties of Biomass Activated Carbon from Ginger Stems

Jinling Liu, Xiaoming Song, Shanshan Gao and Fushan Chen

2019,4(4):45-50

Biomass activated carbon (BAC) was produced from ginger stems by carbonization and activation presented high specific surface areas and mesoporous structures. The carbonization temperature of the ginger stems were controlled within 500~900℃. The optimal carbonization condition is as follows: carbonization temperature of 700℃, carbonization time of 6 h. The determined optimum activation condition is: temperature of 800℃, activator of KOH and carbonized product/alkali ratio of 1:4 (w/w). The carbonization yield, BAC yield and Brunauer-Emmett-Teller (BET) surface area were measured and the adsorption performance of BAC to nitrogen was investigated. The results showed that the nitrogen adsorption isotherm curve was as type I isotherm. It was finally determined that the BET surface area was 660 m2/g under the abovementioned optimal conditions of carbonization and activation. The FESEM analysis indicates that the obtained BAC is of micropore structure.

[Abstract] [PDF]

Study on Refining Performances in Chemi-mechanical Pulping of Mixed Poplar and Eucalypt Woodchips

Yu Shi, Qun Li and Yujia Zhang

2019,4(4):51-56

The refining performances of mixed poplar and eucalypt woodchips (mixture ratio 6:4) were investigated at medium and high pulp consistency via chemi-mechanical pulping (CMP). The specific refining energy consumption (SEC), fiber fraction proportion, and Canadian standard freeness (CSF) were determined to evaluate the effects of pulp consistency and NaOH dosage on the refining performances of mixed poplar and eucalypt woodchips. While the dosage of NaOH for impregnation was maintained constant, the SEC and shive content increased with increasing pulp consistency. Different fractions obtained from the Bauer-McNett classifier showed that higher pulp consistency could be expected to yield more long fibers and shive in the stock. Upon increasing the NaOH dosage, the shive content and SEC reduced significantly. When the NaOH dosage was increased to 6%, the results indicated that it was difficult to reduce the shive content to less than 1% at high pulp consistencies (25%~35%), whereas 0.18% shive fraction could be achieved at a medium pulp consistency (15%).

[Abstract] [PDF]

PSO-based Parameter Tuning for a Two-Degree-of-Freedom IMC Scheme and Its Application to Paper Basis Weight Control

Wei Tang, Zhimin Yuan, Wenjuan Shan and Md. Muhie Menul Haque

2019,4(4):57-63

Basis weight is an important indicator for evaluating paper quality and a major factor directly affecting the economic benefits of enterprises. Focusing on the large time-delay, time-varying, and nonlinear characteristics of a basis weight control system, a two-degree-of-freedom (TDF) internal model control (IMC) method based on a particle swarm optimization (PSO) algorithm was proposed. The method took the integral of time multiplied by the absolute error (ITAE) as the objective function, and the PSO algorithm was used to optimize the time constant of the tuning IMC filter. The simulation results for the control system under the proposed TDF-IMC method based on the PSO algorithm demonstrate good set-point tracking performance, strong anti-interference capabilities, and good robustness properties. The application results revealed that the basis weight fluctuation range of the paper was ±2 g/m2, which significantly improved both the control quality and the product quality.

[Abstract] [PDF]

2nd Editorial Board of Paper and Biomaterials

2019,4(4):64-70

[Abstract] [PDF]