Influence of silica nanoparticles on the desalination performance of forward osmosis polybenzimidazole membranes

Polybenzimidazole (PBI) is a chemically and thermally stable polymer, which is being considered for forward osmosis (FO) seawater desalination in regions with high seawater temperatures and salinities. In this work, FO flat sheet membranes were fabricated using non-solvent induced phase separation (NIPS) method from PBI dope solution incorporated with silica nanoparticles (SNPs) at different concentrations (0, 0.5, 1 and 2 wt%). The influence of draw solution concentration, cross-flow velocity and membrane cell orientation on the performance of pristine PBI and PBI/SNP membranes was examined. Results showed that the performance of the PBI/SNP membranes improved compared to the pristine PBI membrane. Addition of 0.5 wt% of SNPs to PBI membranes (S0.5) reduced the membrane's structural parameter (809.4 mu m vs. 1193.2 mu m), augmented the tensile strength (31.9 MPa vs. 27.3 MPa), and increased water flux by two folds (16.9 Lm(-2) h(-1) vs. 7.4 Lm(-2) h(-1)) compared to the pristine PBI membrane (SO). Given the thermal stability of the PBI/SNP membrane along with its improved water permeation performance, the modified membrane offers a promising option for the FO process in hot and arid zones.