Cr(Ⅵ)and phenol are toxic contaminants that need to be treated,and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater.In this study,Cr(Ⅵ)was used as a n...Cr(Ⅵ)and phenol are toxic contaminants that need to be treated,and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater.In this study,Cr(Ⅵ)was used as a novel Fenton-like catalyst in phenol degradation by H2O2.In the pH range of 3.0-11.0,the degradation efficiency of phenol decreased with elevated pH.At pH=3.0,100 mg/L phenol was effectively degraded by 2 mmol/L Cr(Ⅵ)and 20 mmol/L H2O2.At pH=7.0 and the same conditions as those of pH=3.0,79%of 100 mg/L phenol was removed within 6h,which was an improvement in pH limitation compared with the Fe(Ⅱ)-mediated Fenton reaction.Quenching experiments indicated that·OH generated from the catalysis of H2O2 by Cr(Ⅴ)instead of Cr(Ⅵ)was the primary oxidant that degraded phenol.When pyrophosphate was added in the Cr(Ⅵ)/H2O2 system,complexes with the Cr(Ⅴ)intermediate rapidly formed and inhibited H2O2 decomposition,implying that the decomposition of H2O2 to·OH was catalyzed by Cr(Ⅴ)instead of Cr(Ⅵ).The presence of anions such as chloride and sulfate had insignificant effect on the degradation of phenol.TOC and UV analyses suggest that phenol could not be completely oxidized to CO2 and H2O,and the intermediates identified by high performance liquid chromatography further indicates that maleic acid and benzoquinone were intermediates which may be further degraded into short chain acids,primarily maleic,formic,acetic,and oxalic acids,and eventually into CO2 and H2O.Considering that more than 50%Cr(Ⅵ)can also be removed during this process,the Cr(Ⅵ)/H2O2 system is more appropriate for the simultaneous removal of Cr(Ⅵ)and phenol contaminants from industrial wastewater.展开更多
基金supported by the National Natural Science Foundation of China (No. 41373114 and 51508384)the Natural Science Foundation of Tianjin (No. 15JCZDJC40200)the Foundation of Key Lab of Indoor Air Environment Quality Control (Tianjin University)
文摘Cr(Ⅵ)and phenol are toxic contaminants that need to be treated,and different methods have been researched to simultaneously remove these two contaminants from industrial wastewater.In this study,Cr(Ⅵ)was used as a novel Fenton-like catalyst in phenol degradation by H2O2.In the pH range of 3.0-11.0,the degradation efficiency of phenol decreased with elevated pH.At pH=3.0,100 mg/L phenol was effectively degraded by 2 mmol/L Cr(Ⅵ)and 20 mmol/L H2O2.At pH=7.0 and the same conditions as those of pH=3.0,79%of 100 mg/L phenol was removed within 6h,which was an improvement in pH limitation compared with the Fe(Ⅱ)-mediated Fenton reaction.Quenching experiments indicated that·OH generated from the catalysis of H2O2 by Cr(Ⅴ)instead of Cr(Ⅵ)was the primary oxidant that degraded phenol.When pyrophosphate was added in the Cr(Ⅵ)/H2O2 system,complexes with the Cr(Ⅴ)intermediate rapidly formed and inhibited H2O2 decomposition,implying that the decomposition of H2O2 to·OH was catalyzed by Cr(Ⅴ)instead of Cr(Ⅵ).The presence of anions such as chloride and sulfate had insignificant effect on the degradation of phenol.TOC and UV analyses suggest that phenol could not be completely oxidized to CO2 and H2O,and the intermediates identified by high performance liquid chromatography further indicates that maleic acid and benzoquinone were intermediates which may be further degraded into short chain acids,primarily maleic,formic,acetic,and oxalic acids,and eventually into CO2 and H2O.Considering that more than 50%Cr(Ⅵ)can also be removed during this process,the Cr(Ⅵ)/H2O2 system is more appropriate for the simultaneous removal of Cr(Ⅵ)and phenol contaminants from industrial wastewater.
