Catalytic ozonation of NH4+-N in wastewater over composite metal oxide catalyst

• 作 者: Caiqing He Yunnen Chen Lin Guo Ruoyu Yin Tingsheng Qiu
• 机 构: Jiangxi Key Laboratory of Mining & Metallurgy Environmental Pollution Control,Jiangxi University of
• 出 处: 稀土学报（英文版）
• 发表日期: 2022年1期
• 关键词: Ammonium nitrogen Catalyst Wastewater Catalytic ozonation Rare earths

Large amounts of water containing-ammonium nitrogen (NH4+-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 com-posite metal oxide catalysts prepared with different preparation conditions were used to degrade wastewater containing inorganic pollutant (NH4+-N).The as-prepared catalyst features were character-ized using X-ray diffraction (XRD),Brunauer-Emmett-Teller method (BET),scanning electron micro-scopy (SEM),energy dispersive X-ray spectroscopy (EDS),Fourier transform infrared spectroscopy (FT-IR),X-ray photoelectron spectroscopy (XPS) and H2-temperature programmed reduction (H2-TPR)techniques.The results show that the catalyst,prepared by conditions with precipitant Na2CO3 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 NH4+-N and selectivity to gaseous nitrogen,88.14 wt％ and 53.67 wt％,respectively.The effects of several operating factors including solution pH,initial NH4+-N concentrations and scavengers were evaluated.In addition,XRD patterns of catalyst with the best performance and the comparative study on decontamination of NH4+-N by various processes (O3,catalyst and catalyst/O3) show that the primary metal oxides are CeO2 and MnO2 in Ce/MnOx composite metal oxide catalysts,which have a synergistic effect on the catalytic ozonation of NH4+-N,and the new phase MnO2 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 NH4+-N was investigated.Possible mechanism and degradation pathway of NH4+-N were also proposed.In a word,the application of CeO2-MnO2 composite metal oxide catalysts in catalytic ozonation can be regarded as an effective,feasible and promising method for the treatment of NH4+-N.