摘要
Nitrate(NO_(3)^(-))removal by photochemical-reduction has received extensive attention.However,the low selectivity of NO_(3)^(-)reduction to N_(2)hinders the application of this technology.In this study,a novel Cu@Fe-Cu-CuFe_(2)O_(4)-x photocatalyst was prepared by modifying CuFe_(2)O_(4)with KBH4 and Cu(II),and used to selectively reduce NO_(3)^(-)to N_(2)with a two-step reduction process.In step(1),with Cu@Fe-Cu-CuFe_(2)O_(4)-x/ultraviolet(UV)system,91.0%NO_(3)^(-)was reduced to 52.3%NO_(2)-and 39.4%N_(2)within 60 min.The rapid removal of NO_(3)^(-)was due to the synergistic effect of oxygen vacancies,Fe-Cu corrosion cell,and CuFe_(2)O_(4)photocatalysis.In step(2),H_(2)C_(2)O_(4)and H_(2)O_(2)were introduced into the effluent of step(1)to promote CO_(2)·-formation via Fe(II)and Fe(III)catalysis and UV radiation,which boosted the selective reduction of NO_(2)-to N_(2).When H_(2)C_(2)O_(4)and H_(2)O_(2)dosages were both 4.0 mmol·L^(-1)and the reaction time was 30 min,the removal efficiency of NO_(2)-achieved 100%and the selectivity of N_(2)was 83.0%.Overall,the two-step reduction process achieved 95.0%NO_(3)^(-)removal efficiency and 90.1%N_(2)selectivity with initial NO_(3)^(-)concentration of 30 mg·N·L^(-1).In addition,the denitrification mechanism of the two-step reduction process was tentatively proposed.
基金
The research was financially supported by the National Natural Science Foundation of China(No.52070136)
Applied Basic Research Project of Sichuan Science and Technology Department(No.21YYJC1289)
The authors also extend their appreciation to the Deanship of Scientific Research at King Khalid University for funding support through large group Research Project(No.RGP2/199/44).
