Green rust (GR) and glucose oxidase (GOX) based Fenton-like reaction: Capacity of sustainable release, promoted conversion of glucose through GOX-iron and pH self-adjustment

Abstract

The Fenton reaction is regarded as highly efficient for the degradation of organic contaminants. However, the traditional Fenton reaction is still flawed in a narrow pH working range and low utilization efficiency of the reagents. Based on two striking features, a sustained release of H2O2 in-situ under the catalysis of glucose oxidase (GOX) and the rapid electron donation & transferability from green rust (GR), an adaptable biological Fenton-like system (GGGMFs) was established. The coupling roles of glucose, GOX and GR in the degradation of 3,4-dimethylaniline (3,4-DMA) and the types of reactive species were deduced by electron spin resonance (ESR), etc.. Results demonstrated that the suitable pH range of the system was optimized from acidic to circumneutral, which was favorable for practical application, owing to the heterogeneous formation of GR and the pH self-adjustable capacity of GOX-Glucose. Meanwhile, hydroxyl radical (·OH), superoxide radical (·O2−) and Fe (IV) were identified to be the main oxidizing reactive species. Taking different selectivity of the reactive species to certain pollutant functional groups into consideration, the degradation pathways of 3,4-DMA were proposed. Moreover, it was shown that GR not only acted as the activating substance of the Fenton-like reaction, but also enhanced the activity of GOX, resulting in the promotion of glucose conversion in GGGMFs. This study shed light on the enhancement mechanism consisting of two aspects: (i) the elimination of product inhibition (ii) the formation of a 2Fe(III)-FAD complex with FAD, the active center of GOX, which prompted the electronic transfer in the enzyme catalytic reaction.