Hypothesis: In this study, the composite Ag/Cu₂O nanoparticles were synthesized to fabricate the polyethersulfone (PES) nanofiltration (NF) membranes
Methods: To optimize the nanocomposite PES membranes for NF applications different concentrations of the Ag/Cu₂O nanoparticles were added (0.05, 0.1, 0.5 and 1% by wt) into the pure PES dope solution. Field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR), 3D surface images (AFM) and X-ray diffraction analysis were utilized to investigate physical and chemical properties of the membranes and the nanoparticles. Moreover, the effects of nanoparticles on membrane properties were characterized by water contact angle water content, average pore size, and porosity. Finally, permeability and separation of the membranes were examined in the NF process of sodium sulfate (Na₂SO₄) and copper sulfate (CuSO₄) as a heavy metal
Findings: The results of FE-SEM images and X-ray diffraction analysis depict the formation of nanoparticles. Also, their functional groups can be seen in the FTIR results. The M2 membrane, containing 0.05 wt.% Ag@Cu₂O nanoparticles, showed the highest pure water flux. In detail, the pure water flux increased from 11.2 L/m2.h for the pure PES membrane to 24.36 L/m2.h for the M2 membrane. For the M5 membrane with 1% by wt/Cu₂O, the rejection of Na2SO4 increased to 68.08%, which was higher than that of the pure PES membrane. Moreover, the M5 membrane results in increasing the rejection of heavy metal CuSO₄ up to 98.15% being higher compared to that of the pure PES membrane with a rejection factor of 92.63%. The results of reducing surface roughness and increasing hydrophilic groups lead to improved antifouling properties of the membrane. In addition, the highest amount of flux recovery ratio (FRR%), being 50%, was obtained for the M5 membrane, whilst FRR for the base membrane was about 31.5%.