Magnetic Nanocomposites Containing Low and Medium-Molecular Weight Chitosan for Dye Adsorption: Hydrophilic Property Versus Functional Groups

The azo dye removal from polluted water is vital from a sustainable viewpoint. In this study, we investigated the influence of chitosan molecular weight on the adsorptive removal of basic blue 41. For preparing nanocomposite containing medium-molecular weight chitosan (NC(M)), cross-linking of chitosan was done using diethylenetriaminepentaacetic acid, silica-modified magnetite nanoparticles and graphene oxide. Techniques including FT-IR, XRD, FESEM, TGA/DTG, VSM and N2 adsorption/desorption isotherm were applied for characterization of NC(M). The adsorption behavior of synthesized NC(M) was compared with as-prepared adsorbent containing low-molecular weight chitosan (NC(L)) (Asadabadi 2021). The experimental design was carried out using the Central Composite Design. The effect of initial pH, temperature and adsorbent concentration on the percentage of dye removal were examined and the optimum values of variables were determined. Despite NC(M) which had maximum 31% dye removal, NC(L) led to approximately 95% adsorptive removal at optimum conditions. An increase in the monomer number of chitosan caused to reduce hydrophilic property of NC(M), which in turn resulted in a repulsion force between adsorbent and dye. However, H-bonding, coulumbic attraction and pi-stacking interactions contributed in the adsorption mechanism of NC(L). The kinetics study showed that about 30 min necessitated reaching the equilibrium and the rate-limiting steps changed from film diffusion to intra-particle diffusion as time passed. The kinetics data were satisfactorily fitted by the modified pseudo-n-order model. The maximum adsorption capacity of NC(L) was obtained 55.87 mg·g− 1. The modified Langmuir-Freundlich isotherm was the best model to reproduce data. NC(L) was recovered seven times without dramatic changes in its adsorption efficiency.

The Improvement of Hydrophilic Property of Polyethersulfone Membrane with Chitosan as Additive

Membrane technology has been implemented broadly for clean water treatment. To produce a better membrane, modification is carried out by adding chitosan into a polymer solution. Materials used in this research are polyethersulfone (PES) 18%, the n-methyl pyrrolidone solvent modified with a chitosan solution (at 0.2 – 1 wt%) as an additive, and deionized water as a non-solvent. The membrane synthesis is carried out with the non-solvent induced phase separation method of blending the polymer. Membrane characterization includes functional group analysis, morphological structure, and water contact angle. Membrane performance is monitored at the filtration process, resulting in the permeability coefficient, and for the rejection of a contaminant (humic acid) with dead-end filtration. Research results show that the modified membrane characterization has an asymmetric morphological structure with a thinner top layer, and the membrane sublayer has a finger-like macrovoid structure with a larger size as compared to the original PES membrane (without the chitosan solution addition). The chitosan additive into the PES membrane improves the membrane’s hydrophilic property. The highest value of the permeability coefficient is achieved with a 1% chitosan addition, which provides a permeability coefficient value of 10.524 L/m2.h.bar and a rejection coefficient of 70.3%.

A Study of Wickability of Gauze Products for Infant

Gauze is an excellent material for infant apparel which can made in various forms and by a variety of methods, and thus have attracted great attention in baby care market. This study aims to identify the wicking property of the gauze fabric in baby care products, and to analyse the relationships between the wicking ability and fabric structure of baby soft gauze products. The experimental results revealed that a significant difference occurred for the gauze in the wicking ability. The cotton gauzes were found to show higher wicking rate than bamboo counterparts because of the higher hydrophilic property of cotton material. The fiber content and structure of fabric were the major parameters that affects the wicking ability.