Research On Catayltic Wet Air Oxcidation Of Dye Wasterwater Under Atmospheric Pressure

Wet air oxidation（WAO）,one of advanced oxidation processes（AOPs）,is an effective method for treating a variety of wastewaters with hazardous,toxic and high concentrated organic compounds under high pressure（0.5-20 MPa）and high temperature（125-320oC）.The catalytic wet air oxidation（CWAO）efficiently enhances the oxidative rate of pollutants,decreases the operation conditions and shortens the reaction time,as adding catalysts in WAO process.Therefore,the application of CWAO has widely been paid attention to destroying the pollutants in the wastewater.The development of heterogeneous catalysts with high activity and stability play an important role to its application.In this thesis,the CWAO of cationic red GTL under atmospheric pressure was investigated over heterogeneous catalysts.Fe,as a good environmental-friendly material,was selected as the active phase with doping Ce and Bi.The Fe₂O₃-Ce O₂-Bi₂O₃/γ-Al₂O₃ catalyst was prepared by the co-impregnation method.Under atmospheric pressure the Fe₂O₃-Ce O₂-Bi₂O₃/γ-Al₂O₃ catalyst showed good catalytic activity in the CWAO of cationic of red GTL.By characterization of the catalysts,it was found that the catalyst had a good specific surface area（157m2/g）,the p Hpzc was 7.94 and good dispersion of the α-Fe₂O₃ was obtained due to the addition of Ce or Bi.The performance of Fe₂O₃-Ce O₂-Bi₂O₃/γ-Al₂O₃ catalysts was investigated in the CWAO of cationic red GTL under atmospheric pressure.The results showed that the better decolorization rates of cationic red GTL were achieved alone with the increase of reaction temperature,catalyst loading and p H value of initial solution.When the reaction temperature increased from 60 to 80 oC,the decolorization rate was up from 18% to 67%;the decolorization rate of cationic red GTL rosed from 32.6% to 65.6% in the range of p H value from 4 to 9.Moreover,the activation energy was 79 k J/mol in the CWAO of cationic red GTL over Fe₂O₃-Ce O₂-Bi₂O₃/γ-Al₂O₃ catalyst.To get the insight into the formed active species in CWAO of cationic red GTL over Fe₂O₃-Ce O₂-Bi₂O₃/γ-Al₂O₃ catalyst,the t-butanol and p-benzoquinone were selected as a scavenger of radicals,and para-chlorobenzoic acid（p-CBA）was used as an indicator of hydroxyl radical（OH·）.It was obtained that hydroperoxy or superoxide（HO₂·/O₂-·）,as the main active species,was formed,while OH· was not generated in the CWAO of cationic red GTL.