Fabrication of negatively charged nanofiltration membrane of modified polystyrene intercalated graphene oxide for pervaporation desalination

Abstract

Polystyrene intercalated graphene oxide (GO) membranes with and without sulfonation were successfully prepared for pervaporation desalination applications. The membrane was deposited on nylon support and linked with Zn2+ (c) as a crosslinker. To improve membrane performance, modification of polystyrene via sulfonation was also carried out to convert polystyrene (PS) into polystyrene sulfonic acid (PSSA). The interlayer spacing (d-spacing), hydrophilicity, and stability were observed as the membrane characteristics which greatly influenced the desalination performance. Experimental results show that intercalation of GO with PS and PSSA increases the interlayer spacing and membrane stability. The addition of PS decreased the hydrophilicity of the membrane, while the addition of PSSA increased the hydrophilicity. Calculations for optimizing desalination using Central Composite Design (CCD) on c-PSSA-GO/Nylon membranes show that the optimum temperature and time can be achieved at 57 °C and 71 min. The c-PSSA-GO/Nylon membrane showed the best results with a NaCl rejection value of > 99% and a water flux of 15.56 ± 0.6 kg m-2h−1, which was applied to 1% NaCl feed. The c-PSSA-GO/Nylon membrane also shows consistent NaCl rejection and water flux when applied for an extended period. So, the c-PSSA-GO/Nylon membrane has excellent potential for pervaporation desalination.