Novel Silica Functionalized Monosodium Glutamate/PVA Cross-Linked Membranes for Alkali Recovery by Diffusion Dialysis

Abstract

In this work, two types of silica functionalized monosodium glutamate (GMSG and VMSG)/poly(vinyl alcohol) (PVA) were cross-linked by sol–gel process to prepare novel hybrid cation exchange membranes. The prepared membranes were systematically characterized by FTIR spectroscopy, SEM analysis, ion exchange capacity (IEC), TGA, water uptake, water swelling, mechanical strength and diffusion dialysis performance for alkali separation using NaOH/Na2WO4 solution. The FTIR peaks around 1260–1350 cm− 1 confirmed the secondary C–N linkages. The cross-linking between GMSG/VMSG and PVA was verified by the presence of stretching peaks of Si–O–C, Si–O–Si, C–O–C and –C(=O)–O–C groups between 1080 and 1120 cm− 1. SEM analysis confirmed dense structure and uniform distribution of silica particles in the membrane. TGA results indicated that GMSG membranes showed relatively high thermal stability as compared to VMSG membranes. Water uptake and degree of swelling decreased while IEC values increased with the increase of GMSG/VMSG content in membrane matrix. The mechanical properties of the membranes improved up to 40% GMSG/VMSG content. The NaOH dialysis coefficient (UOH) values improved while values of separation factor (S) declined with the increase of GMSG/VMSG content. Finally, the effect of temperature was studied and it was found that increase in temperature from 25 to 45 °C resulted in increase of diffusion coefficient and decrease of separation factor for both GMSG/VMSG crossed-linked with PVA membranes.