Polyacrylonitrile-based organic-inorganic composite anion-exchange membranes: Preparation, characterization and its application in making ion-selective membrane electrode for determination of As(V)

Organic-inorganic composite anion-exchange membranes based on polyacrylonitrile/silica gel were prepared by solution casting method in different stoicheometric ratios of polyacrylonitrile(PAN) and silica gel. The structure and morphology of the prepared membranes were ascertained by Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and elemental analysis (CHNS/O). The membrane having a composition 1:1 (PAN: silica gel) shows best results for ion-exchange capacity, water content, porosity, thickness and swelling. The As(V) selective electrode was developed by using this membrane for the determination of arsenate in solutions. The membrane electrode shows the best results with linear potential response in the concentration range of 1×10 ^-1molL ^-1 to 1×10 ^-6molL ^-1 of As(V) ion with a slope of 29.75mV/decade. The useful pH of the electrode is 5.0-10.0. The selectivity coefficients values for interfering ions indicate good selectivity for As(V) over interfering anions. The accuracy of the procedure has been tested on arsenic-free drinking water samples spiked with known amount of arsenate and results were comparable to these generated by PCA-Arsenomat (Arsenic Analyzer).