Experimental and theoretical study on the degradation of Benzophenone-1 by Ferrate(VI): New insights into the oxidation mechanism

The oxidation of Benzophenone-1 (BP-1) by ferrate (Fe(VI)) was systemically investigated in this study. Neutral pH and high oxidant dose were favorable for the reaction, and the second order rate constant was 1.03 x 10(3) M-1.s(-1) at pH = 7.0 and [Fe(VI)](0): [BP-1](0) = 10:1. The removal efficiency of BP-1 was enhanced by cations (K+, Ca2+, Mg2+, Cu2+, and Fe3+ , while inhibited by high concentrations of anions (Cl- and HCO3-) and low concentrations of humic acid. Moreover, intermediates were identified by LC-MS, and five dominating reaction pathways were predicted, involving single hydroxylation, dioxygen transfer, bond breaking, polymerization and carboxylation. Theoretical calculations showed the dioxygen transfer could occur by Fe(VI) attacking the C=C double-bond in benzene ring of BP-1 to form a five-membered ring intermediate, which was hydrolyzed twice followed by H-abstraction to generate the dihydroxy-added product directly from the parent compound. Dissolved CO2 or HCO3- might be fixed to produce carboxylated products, and Cl- led to the formation of two chlorinated products. In addition, the toxicity assessments showed the reaction reduced the environmental risk of BP-1. This work illustrates Fe(VI) could remove BP-1 in water environments efficiently, and the newly proposed dioxygen transfer mechanism herein may contribute to the development of Fe(VI) chemistry.

Automated summary

This study systematically investigated the oxidation of Benzophenone-1 (BP-1) by ferrate (Fe(VI)), revealing that neutral pH and high oxidant dose were favorable for the reaction. The study also identified intermediates and predicted five dominating reaction pathways, contributing to a better understanding of Fe(VI) chemistry and its potential application in water treatment.