Treatment of copper-electroplating wastewater by UiO-66-Keratin functionalized PES ultrafiltration membrane

The removal of copper ions from electroplating wastewater has been researched in recent decades including membrane filtration. However, high performance membrane process with lower operating cost is still needed. In this study, a new strategy was developed using an ultrafiltration membrane modified with UiO-66-Keratin through interfacial polymerization. Keratin can form hydrogen bonds and electrostatic interactions with MOF through its amine (-NH₂) and hydroxyl (-OH) groups, enhancing the interfacial compatibility within the membrane. This interaction improves membrane hydrophilicity, antifouling properties, and heavy metal ion rejection. The membranes were characterized in terms of Fourier transform infrared (FTIR), scanning electron microscope (SEM), water contact angle (WCA), and zeta potential. The modification improved the membrane characteristics including hydrophilicity and fouling resistance. Performance evaluation using synthetic wastewater (CuSO₄.5H₂O, 0.1 M, pH 5) and real wastewater showed that the PES/PEG200/UiO-66-5K membrane provided high copper rejection of 78% and 76%, respectively (higher than the pristine PES, 34%). The membrane pure water flux increased by 89.6% for the modified membrane (215.2 L m^-2.h^-1) compared to the pristine PES membrane (22.3 L m^-2.h^-1) while maintaining a high BSA (96.5%) and HA (99.9%) rejection, with flux recovery rates of 78.3% and 98.1%, respectively. These findings indicate significant benefits for increasing the application of the ultrafiltration membrane.