Removal of bisphenol A by cobalt and iron loaded into carbon nanotubes: Synergistic enhancement of electron transfer processes

This study presents a catalytic membrane that combines cobalt-iron-loaded carbon nanotubes as the primary catalyst with graphene oxide as the material for regulating the flow channels (CoFe@CNT-GO). The membrane exhibits exceptional bisphenol A removal efficiency of 98.4 % at a high flux of 120 L/m²/h over a 72-hour period. The CoFe@CNT-GO/PMS system demonstrates outstanding resilience to interference in complex water environments. The synergistic mechanism of Co and Fe is thoroughly investigated. Iron doping significantly increases the proportion of Co(II), enhancing the system's reducibility. The encapsulated structure and strong Co-Fe interaction of CoFe@CNT help reduce Co leaching and improve the membrane's sustainability. Notably, the Co-Fe bimetallic active sites significantly enhance the electron transfer process. Density functional theory (DFT) simulation results showed that the cobalt-iron interface transfers more electrons to a PMS molecule compared to single metal interfaces. Additionally, oxygen vacancies significantly enhance electron transfer between PMS and the catalysts due to the abundance of localized electrons. This work reveals the mechanism of the synergistic effect between Co and Fe in Co-Fe composite catalytic membrane/PMS system and elaborates its prospects in practical water treatment applications.