Catalytic Activation Of Dioxygen To Form Highly Reactive Radicals And Its Effectiveness Study

The dioxygen activation-based advanced oxidation technology have aroused widely concern due to its characters of simple, green and inexpensive. Since the reactive radicals are the key species for the oxidation and degradation of organic pollutant in advanced oxidation technology, it is of great significance to built the simple and highly efficient system for dioxygen activation with highly reactive species generated under mild conditions. In this study, a reducing substances(o-aminophenol, p-aminophenol and hydroquinone)-based “reducing substances/ Co2+-HCO3-”system were built to activate dioxygen catalytically with highly reactive species generated under mild conditions.The development of the catalytic system, the oxidation degradation characteristics, the type and mechanism of reactive oxygen species generated and the effectiveness study of the built system are discussed in details, the following results are achieved in this dissertation from the above experimental research:① The reducing substances-based “reducing substances/Co2+-HCO3-”systems(o-aminophenol, p-aminophenol and hydroquinone) were built successfully for the activation of dioxygen with highly reactive radicals generated. The systems performed well in their catalytic oxidation activity, further effectiveness study indicated that the system showed good activity treating with dye-contained wastewater during the oxidation process of the reducing substances.② The results revealed that OAP was efficiently transformed to a less harmful compound 2-aminophenoxazine-3-one(APZ) by the OAP-Co2+-HCO3- system, Co2+、HCO3-and O2 were necessary for the oxidation of OAP. The interaction of O2 and formed Co II(HCO3-)(OAP) complex lead the formation of O2?-(single electron reduction product) and O22-(two electron reduction product), O22-can transfer to H2O2 by protonation. ESR and radical scavenger study showed that highly reactive metal-bound hydroxyl radical were generated form H2O2 decomposition and it was the main reactive species for the oxidation of OAP.③ The oxidation of PAP occurred both in PAP-HCO3- and PAP-Co2+-HCO3- systems, the addition of Co2+can accelerate the generation of metal-bound hydroxyl radical which is the main reactive species for the oxidation of PAP. The metal-bound hydroxyl radical were generated through two steps:(i) the O2-? mediated production of H2O2, and(ii) the reaction of formed H2O2 with Co2+-HCO3-complex to produce ?OH through Fenton reaction. Simultaneously, the highly reactive radicals generated during the oxidation of PAP contributed to the decoloration and degradation of an typical azo dye Acid Orange II.④ The oxidation of H2 Q occurred both in H2Q-HCO3- and H2Q-Co2+-HCO3- systems, In the solution of HCO3-, Hydroquinone was oxidated to a semiquinone radical through a one-electron transfer followed by a second one-electron oxidation to the benzoquinone, during which O2 was reduced to form H2O2 in bicarbonate solution,The H2O2 can transfer to metal-bound hydroxyl radical for the oxidation of H2 Q, meanwhile, the formed HCO4-partly contribute to the oxidation of H2 Q. Simultaneously, the H2Q-Co2+-HCO3- system was efficient for the degradation of AOII, The interaction between formed?OH and AOII causing contemporaneous cleavage of the two C-N bonds, as a result degradation of the AOII were occurred with the formation N2, p-PSA and 1,2-naphthaquinone.