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

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.