Degradation of oxytetracycline by the in situ hydrogen peroxide-producing photo-Fenton system g-C3N4/CQDs/Fe2+:Mechanism,degradation pathway and toxicity change analysis
Fenton reaction is an oxidation process that generates hydroxyl radicals(·OH)through the decomposition of H2O2 catalyzed by Fe2+,which is widely used for the degradation of organic pollutants in wastewater because of its fast·OH generation rate and simple operation.In this study,the g-C3N4/CQDs/Fe2+ photo-Fenton system was con-structed by adding Fe2+ activated composite photocatalyst graphite phase carbon nitride/carbon quantum dots(g-C3N4/CQDs)to generate H2O2 in situ,which avoids the potential risk of H2O2 during storage and transportation,and broadens the pH range of the reaction.The system showed excellent activity for the degradation of oxytetracycline(OTC)with a high degradation efficiency of 97%at a g-C3N4/CQDs dosing of 120 mg,an initial OTC concentration of 20 mg·L-1,an Fe2+ dosing of 0.36 mmol·L-1,and an initial pH of 7 for OTC solution.The excellent activity of g-C3N4/CQDs/Fe2+ photo-Fenton degradation of OTC based on experiments such as radical capture,determination of changes in the generation of·OH and comparison with the H2O2 generation process was demonstrated to be mainly derived from the·OH active species generated by Fe2+ activation of in situ H2O2 production.Further,the inter-mediate products of OTC degradation were detected and analyzed by mass spectrometry,and the possible degrada-tion paths of OTC were inferred.In addition,by measuring the optical density(OD600)value to obtain the growth curve of bacteria,the results showed that the toxicity of the reaction solution gradually decreased with the degrada-tion of OTC by g-C3N4/CQDs/Fe2+.Finally,compared with the conventional Fenton system with the addition of H2O2 to degrade OTC,the results showed that the photo-Fenton system can basically achieve the effect of conven-tional Fenton,and it is not limited by the pH range which provides a new idea for improving the applica-tion of Fenton reaction in actual wastewater treatment.
NETL
NSTL
万方数据
