Cellulose

Zhu, Xing; Lv, Zuoyuan; Ren, Longfang; Fan, Mingliang; Du, Chenxi; Qiang, Yuanyuan; He, Bin

2024 Cellulose

doi: 10.1007/s10570-024-06165-4

Enzyme immobilization has emerged as one of the pivotal technologies in enzyme engineering, offering substantial cost reductions associated with enzyme isolation and utilization. However, efficient catalysis of solid substrates with solid immobilized enzymes remains a challenge, typically exemplified by the hydrolysis of cellulose using immobilized cellulase. In this study, a novel system of reversible release and recycling of cellulase on the surface of low-density polyethylene (LDPE) "hull" was developed, inspired by the operational dynamics of carrier-based aircraft. The reversible formation and disruption of multiple hydrogen bonds between the grafted gelatin molecular chain on the LDPE surface and the modification arm of cellulase (poly (methacrylic acid-propenoic acid; PAA-PMAA) can be achieved through temperature control, thus enabling the reversible release and recycling of modified cellulase molecules on the LDPE surface. Results demonstrated that the release of modified cellulase (PLANE) from the LDPE surface overcame the mass transfer barrier inherent in traditional immobilized enzyme systems for catalyzing insoluble substrates. This was attributed to the dissolution of PLANE in the developed system, rendering its hydrolysis of the insoluble cellulose substrate comparable to that of the free enzyme. Upon completion of the reaction, the PLANE could be reversibly recycled on the surface of the macroscopic LDPE membrane, facilitated by the regeneration of multiple hydrogen bonds. Furthermore, the facile removal of the membrane aided in the convenient recycling of cellulase. Notably, the cellulase molecules in the system retained more than 50% of their biological activity even after 8 batches of reuse, making the process cost-effective. This method addressed the limitations of traditional immobilized enzymes, allowing the catalysis of solid substrates with elevated mass transfer and simultaneous easy recovery, thus standing out as a universal immobilization method.

Sasikala, M.; Magesan, P.; Dhanalekshmi, K. I.; Umapathy, M. J.

2024 Cellulose

doi: 10.1007/s10570-024-06101-6

A lot of attention has been paid to cellulose nanocrystals (CNCs) due to their wide availability with a great potential to replace synthetic materials. The formation of CNCs from agricultural waste has numerous positive economic and environmental consequences. Cellulose nanocrystals were synthesized from pineapple leaf by acid hydrolysis and characterized by FT-IR, XRD, SEM, TEM, etc. Different concentrations of cellulose nanocrystals (1%, 3%, and 5% w/w) reinforced gelatin-based bio-nano composite was coated on tissue paper. The optimized fibrogenic solution was infused with three different plant leaf extracts (Banana leaf extract, Mantharai leaf extract, and Lotus leaf extract) used as an antimicrobial agent for hygienic tissue paper. Thickness, grammage, and bulk density analysis show the efficiency of the coating formation. The coated tissue paper shows increased mechanical properties and air permeability but significantly reduced water vapour permeability. Antimicrobial efficacy showed improved activity against Gram-positive bacteria Staphylococcus aureus (ATCC-2913), Gram-negative bacteria Escherichia coli (ATCC-27853), and fungi Candida glabrata (NCYC 388). These results reveal the potential of cellulose materials to serve as accessible platforms for anti-infective or self-sterilizing materials against both bacteria and fungi.Graphical abstract[graphic not available: see fulltext]

Islam, Makdud; Sinha, Akhouri Sanjay Kumar; Prasad, Kamlesh

2024 Cellulose

doi: 10.1007/s10570-024-06125-y

Cellulosic fiber from rice straw provides a sustainable alternative to the environmental menace of the field burning problem. Response surface methodology and artificial neural network were applied in the organosolv pulping process to evaluate the responses of total pulp yield (TPY, %), holocellulose content (HC, %), and Klason lignin (KL, %). The optimum input parameters for these reactions were solvent ratio (formic acid: acetone 8:2), chemical doses (68%), time (269 min), and temperature (106 °C) with a response value of TPY (49.8%), HC (80.35%) and KL (3.85%). Artificial neural networks showed better-optimized results as compared to the response surface methodology. An exceptional fiber separation was observed using SEM analysis, while FT-IR analysis confirmed the significant removal of lignin as per drastic reduction in the absorption band at around 1505 cm−1. The cellulose maximization and lignin reduction in the optimized pulp were also confirmed using EDX, XRD, and TGA analysis. Further, the effects of the addition of cationic starch, carboxymethyl cellulose, and xanthan gum were studied for making fiber composite hand sheets. The surface properties were optimum at the bio-additive doses of 3% (oven-dried) in both cases. However, the strength properties reached the maximum with the addition of 2% bio-additives. Nevertheless, cationic starch showed more suitable bio-additive for hand sheet packaging papers with better surface and strength properties. This study determined the optimum organosolv process parameters at the lab scale and further confirmed the suitability of the developed material for packaging applications with improved strength, surface, and optical properties.

Jia, Xiaoxue; Schwab, Natalie L.; Zhang, Xin; He, Yiyang; Ma, Peihua; Wang, Qin; Mao, Yimin; Briber, Robert M.

2024 Cellulose

doi: 10.1007/s10570-024-06158-3

A facile, efficient, and high yield method for producing chitin nanocrystals (ChNCs) using ultrasound-assisted phosphoric acid (PA) hydrolysis was developed. The hydrolysis was conducted at high chitin loading of 40 wt% and at a mild temperature of 50 °C, with the chitin-PA mixture remaining in a solid paste-like form throughout the reaction. The ChNCs produced showed an average length of ~ 200 nm and a cross-section of ~ 20 nm. Three reaction conditions were compared, at PA concentrations of 65, 75, and 85 wt%. Negligible changes in the sizes of ChNCs and degree of acetylation (DA) of the chitin (~ 96%) were observed, while the ChNC yield varied from 75.1 wt% at 65 wt% PA concentration to 49.6 wt% at 85 wt% PA concentration. The ChNCs were weakly charged, with a ζ-potential of ~  + 27 mV, owing to the inherent deacetylated N-acetyl groups. Overall, ultrasound-assisted PA processing provides an efficient and relatively environmentally-benign method for ChNC production.

Lu, JiaYu; Yu, Jin; Jiang, Ziqing; Zhang, Yan; Zhang, Hao; Yu, Yihao; Qi, Dongming; Wang, Jianming

2024 Cellulose

doi: 10.1007/s10570-024-06150-x

With the escalating prevalence of electromagnetic radiation pollution, flexible electromagnetic interference (EMI) shielding materials hold immense potential for widespread application. Carbonized fabric possesses notable advantages such as flexibility, excellent electrical conductivity, and chemical stability. However, its traditional preparation process is characterized by high energy consumption, intricate atmospheric conditions, and prolonged duration. This study introduces a novel approach of incorporating intumescent flame retardant (IFR) into cotton fabric, aiming to facilitate rapid carbonization in an air atmosphere. Remarkably, this innovative approach yields an outstanding total EMI shielding effectiveness (SET) of 17.55 dB within a mere 5 min carbonization process at 900 °C under ambient air conditions. Moreover, in order to enhance the shielding effect, we conducted in-situ growth of polypyrrole (PPy) on the prepared carbonized fabric. The deposition time of 120 min resulted in an impressive SET value of 28.22 dB, effectively providing a shielding capability of up to 99.9% against electromagnetic waves (EMW). Moreover, the SET value of IFR-C-PPy-60 min can be enhanced to 51.84 dB by stacking 4 layers, enabling the attenuation of 99.999% of EMW. The IFR-C-PPy also demonstrated exceptional fire safety and thermal stability. This study presents a novel approach for the rapid and large-scale fabrication of highly efficient conductive carbonized fabric, which demonstrates potential applications in flexible electronic devices.Graphical abstract[graphic not available: see fulltext]

Zhuang, Jie; Lv, Jinlin; Jin, Wanhui; Yu, Qian; Yu, Jing; He, Li; Tang, Xiaoning; Ran, Wenhua; Cai, Guangming; Cheng, Deshan; Wang, Xin

2024 Cellulose

doi: 10.1007/s10570-024-06159-2

Functional aerogels have attracted intensive attention due to their large specific surface area and light weight. In this study, liquid metal (LM) was uniformly dispersed into carboxymethyl cellulose nanofiber (CCNF) for fabricating sustainable CCNF/LM aerogel using a freeze-drying method. The as-fabricated CCNF/LM aerogel was characterized to understand its morphology, chemical components, crystal structure and surface structure, and the sound absorption together with thermal insulation of the aerogel were measured. The CCNF/LM aerogel exhibited good sound absorption, which can be attributed to the unique three-dimensional layered structure. Furthermore, the surface temperature of the CCNF/LM aerogel can be effectively decreased due to the heat absorption, reflection, and radiation of liquid metal. This work provides strategies in developing LM-aerogels toward application of in noise reduction and thermal insulation.

Signori-Iamin, Giovana; Aguado, Roberto J.; Tarrés, Quim; Santos, Alexandre F.; Delgado-Aguilar, Marc

2024 Cellulose

doi: 10.1007/s10570-024-06145-8

While cationic cellulose has yet to find a place in the paper industry, manufacturers show certain interest in a more recent material: cellulose nanofibers (CNFs), generally with negative surface charge. This work suggests both to be combined to increase the mechanical properties of recycled paper while preventing the use of synthetic polyelectrolytes as retention agents. On one hand, a bleached pulp was cationized by etherification, both as-is and following mechanical refining (15,000 PFI revolutions) and submitted to high-pressure homogenization, generating two different kinds of cationic CNFs. On the other, the same pulp was submitted to an enzymatic pretreatment and high-pressure homogenization, producing a negatively charged cellulose micro/nanofiber (CMNF). Two different cellulose-based systems consisting of each type of cationic CNF and the enzymatic CMNF were applied in the papermaking of both virgin and recycled paper. This study demonstrates the effective use of the cationic CNFs as retention agents during sheet formation, which together with the enzymatic CMNFs significantly enhanced the mechanical properties of both types of paper. The study found that refining before cationization favored the retention effect, primarily due to increased surface area and charge of the cationic CNFs, where remarkable increases in the breaking length of virgin (125.1%) and recycled paper (46.5%) were reached. The synergy between cationic CNFs and enzymatic CMNFs outperformed the use of commercial polyacrylamide, a non-biodegradable polyelectrolyte. This research highlights the potential of tailored CNFs in producing high-performance papers, while promoting sustainability and offering a plausible strategy to increase paper recycling rates.

Sanjeevi, R.; Jafrey Daniel James, D.; Senthamaraikannan, P.

2024 Cellulose

doi: 10.1007/s10570-024-06160-9

The need for natural fibers has increased in recent years due to more environmental consequences, which led to the exploration of novel biofibers. This research deals with extracting and characterizing fiber extracted from Cymbopogon nardus roots. The C. nardus root fibers were obtained from the roots of the C. nardus plant by manually retting. The C. nardus root fibers were analyzed for physio-chemical, morphological, thermal, crystalline, and mechanical properties. The test results elucidated that the cellulose contents of C. nardus root fibers were 65.67%, and the density was 1192 kg/m3, which was less than synthetic ones to prove its lightweight behavior. The crystallinity index of C. nardus Root fibers was 59.16%, demonstrating the extracted fiber’s higher-order crystal nature. Fourier Transform Infrared Spectroscopy proved the various crystalline and amorphous contents in the C. nardus root fibers. Scanning Electron Microscope elucidated the multiple features of the C. nardus root fibers, demonstrating its suitability as reinforcement for the composite to suit versatile, lightweight, medium-load applications.

Mendonça, Maressa Carvalho; Durães, Alisson Farley Soares; dos Santos, Allan de Amorim; Matos, Lays Camila; Mascarenhas, Adriano Reis Prazeres; Scatolino, Mário Vanoli; Martins, Caio Cesar Nemer; Damásio, Renato Augusto Pereira; Muguet, Marcelo Coelho Santos; Tonoli, Gustavo Henrique Denzin

2024 Cellulose

doi: 10.1007/s10570-024-06162-7

In the search for packaging that causes lower environmental damage, paper has been widely targeted to increase its use in the packaging industries. Still, the water and oil barrier characteristics need to be improved. To correct such deficiencies, different formulations of natural rubber incorporated with cellulose micro/nanofibrils, and carnauba wax were evaluated as alternative coatings of renewable and biodegradable origin on kraftliner and paperboard in the oil and water barrier properties at different grammage (5, 10 and 15 g/m2). The contact angle showed the hydrophobic characteristics of coated papers with angle values of 105° for rubber coatings with micro/nanofibrils and the stability of the water drop with the evaluation of wettability with values close to zero (0.01°/s). The results of Cobb 120 confirmed the hydrophobicity of the coated papers with values close to zero and close to those found by the polyacrylate varnish and the reduction of water vapor permeation by up to 65%. In addition to decreased affinity for water, the papers were also resistant to oil, reaching the maximum resistance value (kit-oil n° 12). Because of these results, natural rubber presents itself as a possible substitute for synthetic materials for covering papers and, together with the micro/nanofibrils of cellulose and carnauba wax, can correct the barrier deficiencies of the papers.Graphical abstract[graphic not available: see fulltext]

Brännvall, Elisabet; Norberg, Lars; Karlström, Katarina

2024 Cellulose

doi: 10.1007/s10570-024-06025-1

The hypothesis was that low residual alkali after cooking would cause lignin re-precipitation during washing and in turn affect the subsequent oxygen delignification stage negatively. To test the hypothesis, kraft cooks were performed in lab-scale to different residual alkali levels, ranging from 5 to 15 g/L and the pulps were subjected to washing with either water or 0.1 M NaOH and then oxygen delignified. The results show that even at low residual alkali and washing with water, the pH in the liquor after washing was above 11 which is sufficiently high to keep lignin in solution. No effect of residual alkali level was observed on the performance of the oxygen delignification stage.