Study On The Mechanism Of Enhancing The Degradation Of Organic Pollutants In Fenton-like System Through Co-existing Substances

Advanced oxidation technology based on hydroxyl radical and sulfate radical has attracted more and more attention in water pollution treatment because it can effectively and quickly oxidize and degrade organic pollutants.The former mainly involves the traditional Fenton reaction based on hydrogen peroxide;the latter mainly involves the persulfate-like Fenton reaction.However,on one hand,the traditional Fenton reaction has the disadvantage of high iron mud output,to further improve the utilization of oxidants is needed;On the other hand,the advanced oxidation technology that activates persulfate to produce sulfate radicals has attracted people’s attention in recent years.Transition metal activation of PMS is a common activation method,in which cobalt ions have the best activation effect,but the use of high concentrations of cobalt ions in the environment is not welcome because it is harmful to human health.Therefore,the use of low-dose catalysts to achieve effective degradation of organic contaminant becomes an urgent problem to be solved.In this paper,the effect of adding coexisting agent on the degradation of organic contaminant by advanced oxidation technology is studied and the amount of catalyst used in the process is reduced.The main research contents are as follows:（1）Phosphate is used to enhance the degradation of phenol by Co²⁺/PMS system,and it can still effectively activate PMS to achieve efficient phenol degradation under the condition of using low concentration of Co²⁺(4μmol L^-1).effects of cobalt ion concentration,phosphate concentration and PMS amount on the reaction system were investigated.The experimental results show that under the conditions of Co²⁺concentration of 4μmol L^-1),PMS concentration of 1 mmol L^-1,and phosphate concentration of 10 mmol L^-1,0.2 mmol L^-1 of phenol can be almost completely degraded in 5 minutes（99.2%）,The effect is much better than the system without phosphate.Electrochemical characterization and Co³⁺accumulation and capture experiments indicate that phosphate may achieve rapid degradation of phenol by reducing the oxidation potential of Co²⁺and promoting the circulation of Co³⁺/Co²⁺.（2）degradation of bisphenol A（BPA）by adding tetracycline（TC）to the Fe³⁺/H₂O₂system to achieve dual degradation of both BPA and TC pollutants.the apparent rate constants of the degradation BPA of the Fe³⁺/H₂O₂and Fe³⁺/H₂O₂/TC systems are compared.It can be seen that the degradation rate constants of the latter(0.30451min^-1)are much higher than the former(0.0027min^-1).Electron straight resonance technology（EPR）shows that the main active species acting on BPA is HO·.The test of Fe²⁺concentration shows that TC achieves rapid degradation of BPA by promoting the circulation of Fe³⁺/Fe²⁺.