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Fabrication of porous chitosan membranes composed of nanofibers by low temperature thermally induced phase separation, and their adsorption behavior for Cu2+

Qin, Wang, Li, Jixiang, Tu, Jianbing, Yang, Hongqin, Chen, Qinhui, Liu, Haiqing
Carbohydrate polymers 2017 v.178 pp. 338-346
acetic acid, adsorbents, adsorption, chitosan, coagulants, copper, ethanol, nanofibers, sodium carbonate, solvents, temperature
Low temperature thermally induced phase separation (LT-TIPS) of chitosan solution was developed to fabricate porous chitosan membranes (p-CSMs), which were composed of short nanofibers with diameter of 40–60nm. Compared to the conventional acetic acid/water solvent, a mixed solvent of acetic acid/ethanol/water was used to prepare chitosan solution. The effect of solvent composition, quenching temperature and time, and coagulant on the p-CSM morphology were systematically explored. The optimum conditions for fabricating p-CSM was to quench 2% chitosan/2% acetic acid in water/ethanol (70/30) at −20°C for 12h, followed by coagulating in 1% Na2CO3 in water/ethanol (50/50). The p-CSM was an effective adsorbent for Cu2+ and had a Langmuir adsorption capacity of 2.57mmol/g, which is close to the adsorption capacity of natural and electrospun chitosan nanofibers. The p-CSM maintained 90% adsorption efficiency for Cu2+ even after six cycles.