Green Approach for Photocatalytic Cu(II)-EDTA Degradation over TiO2: Toward Environmental Sustainability

A green approach was successfully developed to reap three environmental benefits simultaneously: (1) clean water production, (2) hydrogen (H2) generation, and (3) well-dispersed in situ Cu2+ recovery for direct TiO2–CuO composite reclamation, by exploiting the synergistic integration of photocatalytic reaction of Cu-EDTA and one-dimensional (1D) ultralong and ultrathin TiO2 nanofibers. In this light-initiated system, Cu-EDTA was oxidized by TiO2 thus releasing Cu2+ which was reduced and recovered through uniform adsorption onto the long and porous TiO2 surface. A win–win platform was thus attained, on which Cu was recovered while providing active sites for H2 generation via photoreduction of H2O and enhancing photo-oxidation of remaining intermediate oxidation byproducts. Experimental results showed a H2 generation rate of 251 μmol/h concomitantly with TOC reduction. The used TiO2 nanofibers deposited with Cu were reclaimed directly as the TiO2–CuO composite after a facile heat treatment without additional chemicals and subsequently reusable for photocatalytic treatment of other wastewater (glycerol) to cogenerate H2 and clean water under both UV–visible and visible light. This study expounds a significant advancement through an ingenious integration which enhances the environmental sustainability of Cu-EDTA treatment via TiO2 photocatalysis. It also represents a promising and adoptable approach to synthesize other functional composite nanomaterials in a green manner thus broadening its environmental application spectrum, as it promotes industrial environmental management via waste segregation and motivates research to recover more resources from wastewater.