Simultaneous enhanced generation of reactive oxygen species and H2 over Pd-(Cu-s-Fe0) trimetal for bifunctional catalytic degradation of refractory combined pollutants

Abstract

Presently, it is a great challenge to maintain high catalytic reactivity and recycling performance of zero-valent iron (ZVI) for rapid degradation of refractory combined pollutants possessing electron withdrawing groups and electron-donating groups, simultaneously. The state-of-the-art ZVI technique aims to enhance the generation of reactive oxygen species (ROSs) and H2 with the construction of novel noble metals-decorated ZVI-based tri(bi)metal. Herein, we selected the precursors of Cu(NO3)2 and KPdCl6 to synthesize sponge iron (s-Fe0)-based trimetal via interfacial displacement reactions and further disclosed the main influencing factors for detailed evaluation of ideal trimetal. The results show that the preferred palladised copper-decorated s-Fe0 (0.025 wt%Pd-(5 wt%Cu-s-Fe0)) with 30 g/L input dosage could achieve ∼ 90% removal of 20 mg/L rhodamine B (RhB) within four recycling tests. The aeration process over trimetal (Pd-(Cu-s-Fe0)/O2) as well as the addition of H2O2 (Pd-(Cu-s-Fe0)/H2O2) further achieves high catalytic reactivity and recycling performance. Moreover, Pd-(Cu-s-Fe0) could effectively degrade a series of combined pollutants including RhB + triclosan and RhB + tetrabromobisphenol A (TBBPA), respectively. Furthermore, the interfacial nanostructures of Pd–Cu covering the surface of trimetal have been characterized and the variations of ROS have been recorded with electron spin resonance (ESR) signals. Additionally, the bicatalytic mechanism over Pd-(Cu-s-Fe0) has been explored. Accordingly, the simultaneous generation of ROSs and H2 over Pd-(Cu-s-Fe0) highlights the significant potential for rapid degradation of a series of refractory combined pollutants.