Highly adsorptive polysulfone/hydrous iron-nickel-manganese (PSF/HINM) nanocomposite hollow fiber membrane for synergistic arsenic removal

Abstract

The integration of nanotechnology and membrane technology has led to the development of nanocomposite membranes that endowed with outstanding performances for arsenic removal in water system. In this study, a novel adsorptive nanocomposite membrane was fabricated by incorporating novel hydrous iron-nickel-manganese trimetal oxides (HINM) nanoparticles into polysulfone (PSf) membrane. HINM with atomic ratio of Fe:Ni:Mn of 3:2:1 was first synthesized by oxidation and coprecipitation method. The PSf/HINM membranes were fabricated by dry-jet wet spinning phase inversion technique. The physicochemical properties of the membranes were observed by contact angle goniometer, scanning electron microscope (SEM) and atomic force microscope (AFM). H1.5 PSf/HINM membrane shows maximum adsorption capacity of 41.90 mg/g and water flux of 173.82 L/m2 h.bar. This membrane was fabricated by impregnating 1.5 wt% of HINM nanoparticles within 18 wt% of PSf, 5% PVP, and 78% NMP solution. The experimental data of arsenite adsorption were best fitted into pseudo-second order and Freundlich isotherm models. The mechanism of arsenite removal on PSf/HINM membrane involved both chemisorption and physisorption. Chemisorption is concerned to hydroxyl substitution by arsenite ions through the formation of inner-sphere complex, while physisorption associated to electrostatic attraction between arsenite ions and the surface charge of HINM nanoadsorbents. Leaching test demonstrated that HINM was stably incorporated within the membrane matrix. Continuous adsorption-filtration study showed that H1.5 membrane has successfully treated arsenic contaminated water to meet the maximum level (0.01 mg/L) set by World Health Organization (WHO). The membrane could be easily regenerated using 0.1 M NaOH solution. Hence, development of adsorptive nanocomposite PSf/HINM membrane is a promising solution for synergistic arsenic removal in water system due to both adsorption and filtration properties of the membrane.