Fabrication of silver nanoparticles decorated polysulfone composite membranes for sulfate rejection

The tactic of embedding functional nanomaterials into ultrafiltration (UF) membranes has been investigated in order to augment the integrated properties of the hybrid membranes. Mixing of hydrophilic inorganic nanoparticles or nanofillers into the polymeric membranes to form organic-inorganic nanocomposite membranes were found to be quite effective in improving membrane hydrophilicity. In the present study, polysulfone (PSf) membrane of three different compositions (9, 12, 18 wt%) in-situ immobilized with silver nanoparticles were fabricated using phase-inversion technique. The surface morphology of the membranes were studied by field emission scanning electron microscope (FESEM). The uniformity of the distributed nanoparticles and the elemental compositions were proved by energy dispersive x-ray Spectroscope (EDS). BET (Brunauer-Emmett-Teller), nitrogen adsorption measurement has revealed the increase in surface area from 10.15 to 18.85 m²/g for polysulfone membrane and 12.31 to 20.62 m²/g for silver-polysulfone (Ag-PSf) membrane. The surface charges of the fabricated membranes were studied using zeta potential measurements. Furthermore, water flux and sulfate rejection measurements were also carried out using a cross-flow membrane unit. Among the three different compositions, 12 wt% PSf-Ag membranes had significantly higher rejection rate than that of the other membranes.