Preparation of a Cation Exchange Membrane by a Sol-Gel Method-Based Polyvinyl Alcohol to Improve Alkali Recovery via Diffusion Dialysis in the Textile Industry

Abstract

In this work, a novel silane coupled cationic precursor (SAGS) was synthesized by 3-glycidyloxypropyltrimethoxysilane and sodium 2-((2-aminorthyl)amino) ethanesulfonate. A series of cation exchange membranes were prepared with poly(vinyl alcohol) (PVA) and SAGS by a sol-gel-based process. The structure of the prepared membranes were characterized by Fourier transform infrared spectrum (FTIR) and scanning electron microscopy (SEM), and its properties were studied by water uptake (WR), cation exchange capacity (CEC), linear expansion ratio (LER), alkali stability, thermogravimetric analysis (TGA), mechanical properties, and diffusion dialysis performance. FTIR and X-ray photoelectron spectroscopy (XPS) confirmed the successful preparation of SAGS membranes, and SEM images showed that the prepared membranes were dense and uniform. The WR values of the SAGS membranes were in the range of 91.49–122.39%, and the LER values were 17.65–28.21%. In addition, the SAGS membranes had suitable CEC value, good alkali resistance, and thermal stability which ensured the application of membranes in the field of diffusion dialysis (DD) for alkali recovery. In the DD test, the dialysis coefficients of NaOH (UOH) ranged from 0.012 mm/h to 0.023 mm/h, and the separation factors (S) was in the range of 30.77–16.43. In conclusion, the prepared CEM containing silicon oxygen bonds by PVA and SAGS reaction has the advantages of low price, friendly environment, good alkali resistance, simple preparation process, and great application potential in the textile manufacturing wastewater recovery.