Large amounts of water containing-ammonium nitrogen(NH_(4)^(+)-N)have attracted increasing attention.Catalytic ozonation technology,involving the generation of hydroxyl radical(OH)with strong oxidation ability,was ori...Large amounts of water containing-ammonium nitrogen(NH_(4)^(+)-N)have attracted increasing attention.Catalytic ozonation technology,involving the generation of hydroxyl radical(OH)with strong oxidation ability,was originally utilized to degrade organic-containing wastewater.In this paper,Ce/MnOx composite metal oxide catalysts prepared with different preparation conditions were used to degrade wastewater containing inorganic pollutant(NH_(4)^(+)-N).The as-prepared catalyst features were characterized using X-ray diffraction(XRD),Brunauer-Emmett-Teller method(BET),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and H_(2)-temperature programmed reduction(H_(2)-TPR)techniques.The results show that the catalyst,prepared by conditions with precipitant Na_(2)CO_(3) and Ce/Mn molar ratio 1:2 calcined at 400℃for 3 h in pH 11.0,displays the optimal performance,with the removal rate of NH_(4)^(+)-N and selectivity to gaseous nitrogen,88.14 wt%and 53.67 wt%,respectively.The effects of several operating factors including solution pH,initial NH_(4)^(+)-N concentrations and scavengers were evaluated.In addition,XRD patterns of catalyst with the best performance and the comparative study on decontamination of NH_(4)^(+)-N by various processes(O_(3),catalyst and catalyst/O_(3))show that the primary metal oxides are CeO_(2) and MnO_(2) in Ce/MnOx composite metal oxide catalysts,which have a synergistic effect on the catalytic ozonation of NH_(4)^(+)-N,and the new phase MnO_(2) plays a great role.After 5 consecutive use cycles,the degradation efficiency is declined slightly,and can still achieve better than 70 wt%over 1 h reaction.Additionally,the application of catalytic ozonation for actual wastewater on the removal rate of NH_(4)^(+)-N was investigated.Possible mechanism and degradation pathway of NH_(4)^(+)-N were also proposed.In a word,the application of CeO_(2)-MnO_(2) composite metal oxide catalysts in catalytic ozonation can be regarded as an effective,feasible and promising method for the treatment of NH_(4)^(+)-N.展开更多
基金Project supported by the National Key Research Development Program of China(2018YFC1903401)the National Natural Science Foundation of China(51568023,51864021)。
文摘Large amounts of water containing-ammonium nitrogen(NH_(4)^(+)-N)have attracted increasing attention.Catalytic ozonation technology,involving the generation of hydroxyl radical(OH)with strong oxidation ability,was originally utilized to degrade organic-containing wastewater.In this paper,Ce/MnOx composite metal oxide catalysts prepared with different preparation conditions were used to degrade wastewater containing inorganic pollutant(NH_(4)^(+)-N).The as-prepared catalyst features were characterized using X-ray diffraction(XRD),Brunauer-Emmett-Teller method(BET),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and H_(2)-temperature programmed reduction(H_(2)-TPR)techniques.The results show that the catalyst,prepared by conditions with precipitant Na_(2)CO_(3) and Ce/Mn molar ratio 1:2 calcined at 400℃for 3 h in pH 11.0,displays the optimal performance,with the removal rate of NH_(4)^(+)-N and selectivity to gaseous nitrogen,88.14 wt%and 53.67 wt%,respectively.The effects of several operating factors including solution pH,initial NH_(4)^(+)-N concentrations and scavengers were evaluated.In addition,XRD patterns of catalyst with the best performance and the comparative study on decontamination of NH_(4)^(+)-N by various processes(O_(3),catalyst and catalyst/O_(3))show that the primary metal oxides are CeO_(2) and MnO_(2) in Ce/MnOx composite metal oxide catalysts,which have a synergistic effect on the catalytic ozonation of NH_(4)^(+)-N,and the new phase MnO_(2) plays a great role.After 5 consecutive use cycles,the degradation efficiency is declined slightly,and can still achieve better than 70 wt%over 1 h reaction.Additionally,the application of catalytic ozonation for actual wastewater on the removal rate of NH_(4)^(+)-N was investigated.Possible mechanism and degradation pathway of NH_(4)^(+)-N were also proposed.In a word,the application of CeO_(2)-MnO_(2) composite metal oxide catalysts in catalytic ozonation can be regarded as an effective,feasible and promising method for the treatment of NH_(4)^(+)-N.
