The Mn(VII)–H2O2 oxidation process: Abatement of electron-deficient N-containing organic compounds

Abstract

Chemical oxidants applied in water treatment are electrophiles, which preferentially attack sites with higher electron density. This typically results in less efficient oxidative abatement of organic compounds with electron-withdrawing substituents. In this study, we observed that the permanganate-hydrogen peroxide (Mn(VII)–H2O2) process can enhance the abatement of some nitrogenous organic compounds with electron-withdrawing groups more significantly compared to Mn(VII) in absence of H2O2. A comparison of the oxidation of aniline and 4-chloroaniline, N,N-dimethylaniline and p-cyano-N,N-dimethylaniline, and hydrazine and acethydrazide for Mn(VII) and the Mn(VII)–H2O2 process was performed. It was observed that Mn(VII)–H2O2 can specifically enhance the oxidative abatement of the paired target compounds containing electron-withdrawing groups. By addition of Ba2+, to block the Mn(VI) reaction, it was demonstrated that Mn(VI) formed in the Mn(VII)–H2O2 process, was decisive for inducing the enhanced oxidation. This study reveals an interesting novel application of Mn(VII)–H2O2 for oxidative abatement of N-containing electron-deficient organic compounds during water treatment.