Influence of Newly Organosolv Lignin-Based Interface Modifier on Mechanical and Thermal Properties, and Enzymatic Degradation of Polylactic Acid/Chitosan Biocomposites

This article aimed to study the effects of chitosan fiber and a newly modifying agent, based on organosolv lignin, on mechanical and thermal performances and the enzymatic degradation of PLA/chitosan biocomposites. A newly modifying agent based on polyacrylic acid-grafted organosolv lignin (PAA-g-OSL) was synthesized via free radical copolymerization using t-butyl peroxide as the initiator. The biocomposites were prepared using an internal mixer and the hot-pressed method at various fiber loadings. The results demonstrate that the addition of chitosan fiber into PLA biocomposites remarkably decreases tensile strength and elongation at break. However, it improves the Young’s modulus. The modified biocomposites clearly demonstrat an improvement in tensile strength by approximately 20%, with respect to the unmodified ones, upon the presence of PAA-g-OSL. Moreover, the thermal stability of the modified biocomposites was enhanced significantly, indicating the effectiveness of the thermal protective barrier of the lignin’s aromatic structure belonging to the modifying agent during pyrolysis. In addition, a slower biodegradation rate was exhibited by the modified biocomposites, relative to the unmodified ones, that confirms the positive effects of their improved interfacial interaction, resulting in a decreased area that was degraded through enzyme hydrolysis.

Chitosan Fiber as Green Material for Removing Cr(VI) and Cu(II) Contaminants:Adsorption Properties,Kinetics and Machanism

Chitosan (CS) fiber is used as a new green material to remove Cu(II) and Cr(VI) in wastewater.Varying factors, including pH value, dosage of CS, reaction time and original Cr (VI) contents and Cu(II) were studied to investigate the Cr (VI) and Cu(II) removal efficiency.The adsorption of two metal ions by chitosan fiber conforms to the second-order kinetic equation, and can be fitted with Langmuir isotherms. The adsorption process is a spontaneous thermal reaction with both physical adsorption and chemical adsorption, and copper ions reach adsorption equilibrium. It takes longer than chromium ions, but the adsorption effect of copper ions is better. The maximum actual adsorption capacity of copper ions is 539.6 mg/g, and the maximum adsorption capacity of chromium ions is 75 mg/g. SEM, FTIR and XRD were used to characterize the physicochemical properties of CS fiber. The result shows that the complex process of the Cr (VI) and Cu(II) removal involves physical and chemical adsorption, CS fiber have exerted significant role in Cr (VI) and Cu(II) removal.

Study on antibacterial and copper ion removal of chitosan fiber/acetate fiber and yarn for water purification

Use chitosan (CS) fiber and cellulose acetate (CA) fiber with different mixing ratios as raw materials, the kinetic and thermodynamic characteristics of the adsorption process of chitosan fiber/cellulose acetate fiber (CS/CA) ratio of 90:10 are explored, and the adsorption process conforms to the quasi-second-order kinetic equation. It can be fitted by Langmuir isotherm. The adsorption process is a spontaneous thermal reaction with both physical adsorption and chemical adsorption. The best adsorption time is 30 min, the time to reach adsorption equilibrium is 180 min, and the best adsorption pH is 5, the most suitable temperature is 35°C, and rising the temperature is conducive to the fibers adsorption. The materials before and after the CS/CA blended yarn adsorbed copper ions were characterized by XRD, DSC, FT-IR, and the adsorption mechanism was analyzed. In the orthogonal experiment, the copper ions concentration has the most obvious effect on the adsorption capacity, and the temperature has the most obvious effect on the adsorption efficiency. The optimal adsorption combination is that the mixing ratio of chitosan fiber/cellulose acetate (CS/CA) is 80:20, the pH is 5, the temperature is 35°C, and the copper ion concentration is 100 mg L−1. Comparing the adsorption performance of fibers with different mixing ratios, the adsorption performance of CS/CA ratio of 90:10 is the best. The filtration efficiency of the filter material, made of fibers with different mixing ratios, to copper ions is tested, and the filtration performance with a mixing ratio of 90:10 is the best, and the filtration efficiency is 64.33%.

Adsorption Strategy for Removal of Harmful Cyanobacterial Species Microcystis aeruginosa Using Chitosan Fiber

Microcystis aeruginosa is one of the predominant species responsible for cyanobacterial-harmful algal blooms (Cyano-HABs) in water bodies. Cyano-HABs pose a growing number of serious threats to the environment and public health. Therefore, the demand for developing safe and eco-friendly solutions to control Cyano-HABs is increasing. In the present study, the adsorptive strategy using chitosan was applied to remove M. aeruginosa cells from aqueous phases. Using a simple immobilization process, chitosan could be fabricated as a fiber sorbent (chitosan fiber, CF). By application of CF, almost 89% of cyanobacterial cells were eliminated, as compared to those in the control group. Field emission scanning electron microscopy proved that the M. aeruginosa cells were mainly attached to the surface of the sorbent, which was correlated well with the measurement of the surface area of the fiber. We tested the hypothesis that massive applications of the fabricated CF to control Cyano-HABs might cause environmental damage. However, the manufactured CF displayed negligible toxicity. Moreover, we observed that the release of cyanotoxins and microcystins (MCs), during the removal process using CF, could be efficiently prevented by a firm attachment of the M. aeruginosa cells without cell lysis. Our results suggest the possibility of controlling Cyano-HABs using a fabricated CF as a non-toxic and eco-friendly agent for scaled-up applications.