PREPARATION OF POLYSULFONE NANO-STRUCTURED MEMBRANE FOR SULPHATE IONS REMOVAL FROM WATER

Abstract

Polysulfone nanofiltration (NF) membranes with higher pore size and higher charge density are capable of removing metal ions from water. In the present study the graft-modification of ultrafiltration (UF) membranes by UV irradiation was considered. UF membranes were prepared via phase inversion method using polysulfone (17% wt) as polymer and N-methyl-2-pyrrolidone (75% wt) as solvent in which polyethylene glycol with molecular weight of 3000 g/mol (8% wt) was used comparatively as big sized pore former. Prepared UF membrane was modified by polymerization of acrylic acid as monomer in the presence of UV irradiation on the membrane surface. Effect of grafting conditions including acrylic acid concentration and irradiation time on membrane performance properties as pure water flux and sulphate rejection were studied. FTIR-ATR and AFM were employed to characterize the chemical and structural changes on the modified membrane surface. The results showed pure water flux significantly declined and sulphate rejection improved with increase in both graft irradiation time and monomer concentration. At 25 °C, pure water flux of this prepared NF membrane was 13.26 L/m2.h at 300 kPa. The rejection of 96.3% and 58.8 % to Na2SO4 and MgSO4 solutions were obtained respectively. The RMS roughness of this membrane was 1.65 nm which is in the range of NF membrane properties.