Preparation of transparent anti-pollution cellulose carbamate regenerated cellulose membrane with high separation ability

Development of cellulose/ZnO based bioplastics with enhanced gas barrier, UV-shielding effect and antibacterial activity

Development of renewable and biodegradable plastics with good properties, such as the gas barrier, UV-shielding, solvent resistance, and antibacterial activity, remains a challenge. Herein, cellulose/ZnO based bioplastics were fabricated by dissolving cellulose carbamate in an aqueous solution of NaOH/Zn(OH)42-, followed by coagulation in aqueous Na2SO4 solution, and subsequent hot-pressing. The carbamate groups detached from cellulose, and ZnO which transformed from cosolvent to nanofiller was uniformly immobilized in the cellulose matrix during the dissolution/regeneration process. The appropriate addition of ZnO (below 10.67 wt%) not only improved the mechanical properties but also enhanced the water and oxygen barrier properties of the material. Additionally, our cellulose/ZnO based bioplastic demonstrated excellent UV-blocking capabilities, increased water contact angle, and enhanced antibacterial activity against S. aureus and E. coli, deriving from the incorporation of ZnO nanoparticles. Furthermore, the material exhibited resistance to organic solvents such as acetone, THF, and toluene. Indeed, the herein developed cellulose/ZnO based bioplastic presents a promising candidate to replace petrochemical plastics in various applications, such as plastic toys, anti-UV guardrails, window shades, and oil storage containers, offering a combination of favorable mechanical, gas barrier, UV-blocking, antibacterial, and solvent-resistant properties.

Fabrication of carvacrol loaded cellulose acetate phthalate/shellac composite film and its application to mackerel fillets preservation

In this research, the carvacrol (CAR) loaded cellulose acetate phthalate (CAP) /shellac (SH) films were prepared via electrostatic repulsion strategy and casting method. The CAP/SH-CAR films demonstrated excellent tensile strength, while also exhibiting good UV light barrier and thermal stability. The results showed that the addition of CAR significantly improved the barrier of the CAP film to water vapor and oxygen permeability. When the addition amount of CAR was 0.9 % (w/w) with respect to CAP content, the CAP/SH-CAR films exhibited good antibacterial activity and effectively reduced the growth of S. aureus and E. coli by approximately 47.9 % and 50.9 %, respectively. The presence of SH improved the retention rate of CAR in CAP/SH-CAR films, with the retention rate ranging from 45.2 to 56.8 %. Finally, the CAP/SH-CAR films were applied to preserve the mackerel fillets, indicating that the rate of freshness deterioration had been delayed and showing a good freshness preservation effect. Therefore, the CAP/SH-CAR films have the potential to be used as food packaging materials.

Removal of methylene blue from wastewater using ternary nanocomposite aerogel systems: Carboxymethyl cellulose grafted by polyacrylic acid and decorated with graphene oxide

In this study, environmentally-friendly nanocomposite hydrogels were fabricated. These hydrogels consisted of semi-interpenetrating networks of carboxymethyl cellulose (CMC) molecules grafted to polyacrylic acid (PAA), as an eco-friendly and non-toxic polymer with numerous carboxyl and hydroxyl functional groups, which were reinforced with different levels of graphene oxide particles (0.5, 1.5 or 3% wt). Field-emission electron scanning microscopy (FESEM) images indicated that the pore size of the nanocomposites decreased with increasing graphic oxide concentration. The presence of the graphic oxide increased the storage modulus and thermal stability of the nanocomposite hydrogels. The hydrogels had an adsorption capacity of 138 mg/g of a model cationic dye pollutant (methylene blue) after 250 min. Moreover, a reusability test showed that the adsorption capacity remained at around 90% after 9 cycles. Density functional theory (DFT) simulations suggested that the adsorption of methylene blue was mainly a result of π-π bonds, hydrogen bonds, and electrostatic interactions with graphene oxide. Our results indicated that the nanocomposite hydrogels fabricated in this study may be eco-friendly, stable, efficient, and reusable adsorbents for ionic pollutants in wastewater treatment.

Toxic mechanism on phenanthrene-induced cytotoxicity, oxidative stress and activity changes of superoxide dismutase and catalase in earthworm (Eisenia foetida): A combined molecular and cellular study

Phenanthrene (PHE) is an important organic compound, which is widespread in the soil environment and exhibits potential threats to soil organisms. Toxic effects of PHE to earthworms have been extensively studied, but toxic mechanisms on PHE-induced cytotoxicity and oxidative stress at the molecular and cellular levels have not been reported yet. Therefore, we explored the cytotoxicity and oxidative stress caused by PHE in earthworm coelomocytes and the interaction mechanism between PHE and the major antioxidant enzymes SOD/CAT. It was shown that high-dose PHE exposure induced the intracellular reactive oxygen species (ROS) generation, mediated lipid peroxidation, reduced total antioxidant capacity (T-AOC) in coelomocytes, and triggered oxidative stress, thus resulted in a strong cytotoxicity at higher concentrations (0.6-1.0 mg/L). The intracellular SOD/CAT activity in cells after PHE exposure were congruent with that in molecular levels, which the activity of SOD enhanced and CAT inhibited. Spectroscopic studies showed the SOD/CAT protein skeleton and secondary structure, as well as the micro-environment of aromatic amino acids were changed after PHE binding. Molecular docking indicated PHE preferentially docked to the surface of SOD. However, the key residues Tyr 357, His 74, and Asn 147 for activity were in the binding pocket, indicating PHE more likely to dock to the active center of CAT. In addition, H-bonding and hydrophobic force were the primary driving force in the binding interaction between PHE and SOD/CAT. This study indicates that PHE can induce cytotoxicity and oxidative damage to coelomocytes and unearthes the potential effects of PHE on earthworms.

Fabrication of Reusable Carboxymethyl Cellulose/Graphene Oxide Composite Aerogel with Large Surface Area for Adsorption of Methylene Blue

A highly efficient adsorbent for methylene blue (MB) adsorption was developed by combination of carboxymethyl cellulose (CMC) and graphene oxide (GO) via a simple one-step hydrothermal method. The as-synthesized CMC/GO composite aerogel has a mesoporous structure with an average pore diameter of 30 nm and a high specific surface area of 800.85 m²·g⁻¹. Moreover, the CMC/GO composite aerogel demonstrates a significant selectivity for the dye adsorption, especially for MB, where its adsorption capacity can reach 244.99 mg·g⁻¹ with an excellent recyclability for more than nine times. Thus, the prepared CMC/GO composite aerogel would be an effective adsorbent for dyes adsorption, owing to the merits of high efficiency, reusability, and eco-friendliness.

Facile preparation and performance study of antibacterial regenerated cellulose carbamate fiber based on N-halamine

With the outbreak of coronavirus disease (COVID-19) which has incalculable disasters and economic losses, people have given increasing attention to the health and safety of textile and fiber materials. In this study, an eco-friendly, facile, and cost-effective wet-spinning cellulose carbamate fiber technology was developed, and N-halamine regenerated cellulose fiber (RCC-Cl) with rechargeable and rapid bactericidal properties were prepared by the Lewis acid-assisted chlorination method. The chemical properties of the fibers were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, and energy-dispersive X-ray spectroscopy. The mechanical and surface topography of the treated fiber was investigated by tensile testing and scanning electron microscopy. The results showed that the mechanical properties of RCC-Cl fibers can reach a breaking strength of 12.1 cN/tex and a breaking elongation of 41.4% with the optimized spinning process. Furthermore, RCC-Cl showed excellent antimicrobial activities, which can inactivate Escherichia coli and Staphylococcus aureus at a concentration of 10⁷ CFU/mL within 1 min. This work provided a novel approach to produce regenerated cellulose fibers with antibacterial properties, showing great potential in the field of functional textiles.

New insensitive high-energy dense biopolymers from giant reed cellulosic fibers: their synthesis, characterization, and non-isothermal decomposition kinetics

Renewable giant reed has been explored for the first time to develop new advanced high-energy dense biopolymers through carbamate surface functionalization and nitration of native cellulose and cellulose microcrystals.