A novel low-fouling zeolite-polysulfone nanocomposite membrane for advanced water treatment

A novel zeolite-polysulfone composite ultrafiltration membrane was synthesized. 50-1500 mg/L zeolite nanopowder was added in 15% (w/v) polysulfone solution in N, N-Dimethylformamide solvent. The membrane was formed by phase inversion process. It was found that the membrane became more hydrophilic in nature as manifested by 134.3% increase in pure water permeability at 50 psig pressure of 700 mg/L zeolite nanopowder composite as compared to polysulfone membrane. It was also proven by decline in contact angle from 91.08 degrees to 59.89 degrees for the same. The membrane selectivity performance was also improved as exhibited by albumin rejection from 86.39% to 95.31% for the nanocomposite formed with 700 mg/L zeolite nanopowder. Fouling and flux decline were monitored with 5000 mg/L albumin concentration at 50 psig pressure and it was found that the flux decline at the end of 8th hour was 22.41% for 700 mg/L zeolite nanocomposite as compared to 39.8% for virgin polysulfone membrane. However, on increasing nanomaterial loading to 1500 mg/L in the composite, the pure water permeability declined about 19%, contact angle increased from 59.89 degrees to 81.55 degrees, albumin rejection decreased from 95.31% to 80.55% as compared to the nanocomposite with 700 mg/L nanomaterial loading. SEM and AFM images were taken of the virgin polysulfone and the nanocomposite. It was found that at higher concentration, e.g., 1500 mg/L the nanomaterial agglomerates and thus the incentives of using nanomaterial is attenuated at higher concentration. It was found that 700 mg/L zeolite nanomaterial loading was optimum for advanced water treatment applications as the selectivity of membrane for protein separation and the pure water permeability are the highest. Thus, zeolite nanocomposite can work as a low-fouling, high flux membrane for ultrafiltration applications.