Synthesis and characterization of novel g-C3N4 modified thin film nanocomposite reverse osmosis membranes to enhance desalination performance and fouling resistance

Abstract

The modified thin film nanocomposite reverse osmosis (TFN-RO) membranes were fabricated by embedding the synthesized graphitic carbon nitride (g-C3N4) nanosheets as a hydrophilic modifier in the polyamide layer. The g-C3N4 nanosheets were synthesized using thermal oxidation of melamine. SEM and AFM analyses were used to probe the surface changes of the unmodified and modified membranes. The results of AFM analysis showed the decrease in surface roughness of the modified membranes compared to the unmodified one. The contact angle measurement of the membranes indicated the increase in hydrophilicity of the g-C3N4 embedded membranes, which caused to improve in pure water flux. The rejection of NaCl increased with embedding the g-C3N4 nanosheets and reached to its maximum value (99.7%) in the membranes containing 0.015 wt% of nanosheets. The investigation of antifouling performance using BSA/NaCl solution showed that modified membranes with 0.015 wt% of the embedded g-C3N4 nanosheets had the better performance compared with the unmodified membranes.