Study on the degradation of organic dye wastewater by vacuum ultraviolet activated hydrogen peroxide
Using vacuum ultraviolet(VUV)to activate hydrogen peroxide(H2O2)to generate more reac-tive oxygen species(ROS)for decolorization and removal of dyes.The effects of H2O2 dosage,initial pH value of the solution,and initial dye concentration on the degradation of Acid Red G(ARG)and Rhoda-mine B(RhB)in the system were investigated.The results showed that when the dosage of H2O2 was 3 mmol/L,the decolorization rate of ARG and RhB at 80 mg/L could reach 96.3％and 98.4％respec-tively at 7 min.The removal rate of ARG and RhB increased with the increase of initial H2O2 concentra-tion,but their promoting effect on the dye was limited when the concentration exceeded 3 mmol/L.The dye decolorization process follows a quasi first order kinetic model.Under acidic conditions,the decoloriza-tion and degradation of dyes have higher efficiency,while degradation is inhibited in alkaline environments.The free radical capture experiment and EPR detection results indicate that hydroxyl radicals(·OH)and singlet oxygen(1O2)are the main ROS,with·OH accounting for the main role.The presence of inorganic anions(HCO3-,Cl-,NO3-,SO42-)can inhibit dye degradation.Through UV visible absorption spectroscopy analysis,it is preliminarily inferred that ARG is first attacked through the benzene ring,followed by the cleavage of azo bonds and naphthalene rings,and then mineralization;RhB mainly involves the destruction of conjugated structures,N-site deethylation,aromatic ring cracking,and mineralization.
vacuum ultravioletAcid Red GRhodamine Bhydroxyl radical
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