Electric field-driven preparation of highly dispersed ENP membrane and its study on Cr(VI) removal from water

This study successfully employed an electric field-driven physical technique to load nanoscale zero-valent iron (NZVI) onto a polyvinylidene fluoride (PVDF) membrane, resulting in a highly dispersed and stable NZVI-PVDF composite membrane (ENP). This method avoids the generation of toxic substances and significantly suppresses NZVI aggregation and oxidation, making it highly effective for the reduction of Cr(VI) in wastewater. SEM and AFM analyses revealed that, compared to conventional loading methods, this technique effectively reduces NZVI agglomeration. The resulting NZVI particles have an average diameter of 17.29 nm, while the root mean square roughness (Sq) of the membrane surface is 127.338 nm, ensuring a higher availability of Cr(VI) reduction-active sites. Moreover, after NZVI loading, the surface contact angle of the PVDF membrane decreased from 77.4° to 63.1°, indicating enhanced hydrophilicity. Cr(VI) reduction experimental results indicate that under optimal conditions with an applied voltage of 6 kV, pH 2, temperature of 25 °C, and atmospheric pressure, the ENP membrane achieved a Cr(VI) removal efficiency of 99.8 % within 1 h for an initial Cr(VI) concentration of 100 mg/L. These findings demonstrate that the electric field-driven NZVI loading approach will provide a promising, cost-effective, and environmentally friendly strategy for industrial wastewater treatment. It effectively overcomes the issue of NZVI aggregation while expanding its practical applications in water treatment technologies.