A PSf/Amino Acid-Modified Montmorillonite Mixed Matrix Membrane for Arsenic Removal from Water: Preparation and Evaluation of Its Properties

Polysulfone (PSf) mixed matrix membranes were prepared by embedding pristine montmorillonite (Mt) together with amino acid (M-AA)-modified Mt in order to remove arsenic from water. The qualitative and quantitative comparisons were made between mixed matrix membranes and pure PSf membrane by FE-SEM, XRD, contact angle, AFM, pure water flux (PWF) and mechanical strength tests. The XRD and FTIR results showed that Mt was successfully modified with amino acid, and the amino functional groups were protonated. After modification with amino acid, the Zeta potential of Mt changed from negative to positive. Maximum improvement in PWF, porosity and hydrophilicity was obtained for PSf/Mt mixed matrix membrane due to hydrophilic properties of Mt. However, the modified Mt showed good interaction with PSf and increased the mechanical strength of mixed matrix membranes. Furthermore, the adsorption experiments showed the PSf/M-AA membranes with better arsenic removal efficiency because of positive surface charge of M-AA. The obtained results showed that by increasing M-AA content from 0 to 1.5 wt%, pure water flflux, surface hydrophilicity, roughness, mechanical strength and arsenic adsorption capacity of the membranes increased. The neat PSf membrane showed a very low adsorption capacity for As (V), however the adsorption capacities of 1.4 and 16 mg/g were obtained for the mixed matrix membranes each containing 1.5 wt% of Mt and M-AA. Finally, membrane re-usability of the 1.5 wt% M-AA embedded PSf membrane was assessed by conducting five cycles of adsorption experiments and membrane regeneration in a dead-end filtration system. The obtained results confirmed the applicability of the prepared membrane for multiple cycles.