Critical role of zero-valent iron in the efficient activation of H2O2 for 4-CP degradation by bimetallic peroxidase-like

Abstract

Peroxidase-like based on double transition metals have higher catalytic activity and are considered to have great potential for application in the field of pollutant degradation. First, in this paper, a novel Fe⁰-doped three-dimensional porous Fe⁰@FeMn-NC-like peroxidase was synthesized by a simple one-step thermal reduction method. The doping of manganese was able to reduce part of the iron in Fe-Mn binary oxides to Fe⁰ at high temperatures. In addition, Fe⁰@FeMn-NC has excellent peroxidase-like mimetic activity, and thus, it was used for the rapid degradation of p-chlorophenol (4-CP). During the degradation process, Fe⁰ was able to rapidly replenish the constantly depleted Fe²⁺ in the reaction system and brought in a large number of additional electrons. The ineffective decomposition of H₂O₂ due to the use of H₂O₂ as an electron donor in the reduction reactions from Fe³⁺ to Fe²⁺ and from Mn³⁺ to Mn²⁺ was avoided. Finally, based on the experimental results of LC-MS and combined with theoretical calculations, the degradation process of 4-CP was rationally analyzed, in which the intermediates were mainly p-chloro-catechol, p-chloro resorcinol, and p-benzoquinone. Fe⁰@FeMn-NC nano-enzymes have excellent catalytic activity as well as structural stability and perform well in the treatment of simulated wastewater containing a variety of phenolic pollutants as well as real chemical wastewater. It provides some insights and methods for the application of peroxidase-like enzymes in the degradation of organic pollutants.

Keywords: Fe-Mn bimetal; H2O2 activation; POD-like activity; ZVI; p-Chlorophenol (4-CP) degradation.