Preparation of an Cation Exchange Membrane by Sol-Gel Method Based Pva to Improve Alkali Recovery via Diffusion Dialysis in Textile Industry

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 sol-gel 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 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 summary, the prepared membrane had good performance and simple preparation process, which had great application potential in textile industrial wastewater recovery.