Pervaporation and characterization of chitosan membranes cross-linked by 3-aminopropyltriethoxysilane

Chitosan (CS) was cross-linked with 3-aminopropyl-triethoxysilane (APTEOS) to prepare chitosan-silica hybrid membranes (CSHMs). The CSHMs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The results show that there are strong hydrogen bond and covalent bonds formed in the CSHMs matrix, the crystallinity of the CSHMs is lower than that of CS, and silica is well distributed in the CSHMs matrix. The CSHMs exhibited a low degree of swelling (DS) in ethanol/water mixture. Both the solubility and diffusion selectivity increase with increasing ethanol content in the range of 55-95 wt%. The rate of increase in the solubility selectivity is faster than the rate of decrease in the diffusion selectivity with increasing the feed temperature. These caused the permeate ethanol content to decrease with increasing either the feed ethanol content or the feed temperature. Both the permeation flux and water permselectivity increased remarkably with increasing APTEOS content, CSHM-10 containing 10 wt% APTEOS has the highest separation factor of 597 with a flux of 0.887 kg/(m2 h) in PV of 85 wt% feed ethanol at 323 K.