Study On Degradation Of Organic Pollution By Persulfate Activated By Transition Metal Oxide And Hydrotalcite-like Catalyst

Persulfate activation based Advanced Oxidation Process?AOP?has good prospects for treating organic pollution in water environments.Transition metals like Cu²⁺and Co²⁺could activate persulfate in common temperature and pressure.But the homogeneous catalytic reaction often caused metal ions leaching in the solution,which causing secondary pollution to the environment.However,heterogeneous catalysts were easily separated from the treated water for reuse.But heterogeneous catalysts had low persulfate decomposition and stability.In this study,highly efficient and stable transition metal supported catalysts were prepared.CuO-based bimetallic oxide catalyst,CoMgAl-LDH catalyst and CuOx@Co-LDH catalyst were investigated to activate persulfate?peroxymonosulfate PMS,peroxodisulfate PDS?for the degradation of the model compound phenol.The efficiency of each system was studied by phenol degradation.The stability of catalyst was studied by reusability and transition metal ion leaching after reaction.The effect of pH and inorganic anion to system was investigated for practical applications.The mechanism was also studied.The main research contents are as follows:?1?Study on activation of PMS by CuO-ZnO and CuO-MgO catalyst.Both PMS/CuO-ZnO and PMS/CuO-MgO system could efficient remove phenol with small amount Cu²⁺leaching.The organic pollutants degradation was regulated by non-redox active inorganic carrier.The main free radical was traditional SO₄^·-in PMS/CuO-MgO system,but PMS was activated on the surface of the catalyst without free radical in PMS/CuO-ZnO system.The PMS/CuO-ZnO system was almost unaffected by Cl^-,and PMS decomposition was 3.17 times more than PMS/CuO-MgO system.?2?Study on activation of PMS by CoMgAl-LDH catalyst.CoMgAl-LDH catalyst had good recyclability and stability,PMS/CoMgAl-LDH system could provide 95%phenol degradation after six cycles with only 0.05 mg/L Co²⁺leaching.SO₄^·-was the main active species in the system.PMS/CoMgAl-LDH system can be applied to treatment of landfill leachate.COD of leachate was reduced by 75%,when catalyst was 6g/L,PMS was 60mM after 6 hours.The biochemical of leachate was four time than before.?3?Study on activation of PDS by CuO_x@Co-LDH catalyst.CuO_x@Co-LDH catalyst could not only activate PMS,but also activate less active PDS for phenol degradation.PDS/CuO_x@Co-LDH system could effectively degrade phenol in a wide pH range of 5-12,and with less than 0.01 mg/L Cu²⁺and Co²⁺leaching after reaction.PDS/CuO_x@Co-LDH system produced different active free radicals at different initial pH conditions.At pH=5,the main active species in the solution was SO₄^·-and·OH.At pH=7 and 10,beyond SO₄^·-and·OH,there were·O₂^-in the system.Due to the presence of·O₂^-,PDS/CuOx@Co-LDH system had no obvious effect of the inorganic anions.Based on the conclusions,this study provides a new idea based on transition metal activated persulfate system for the treatment of organic pollutants degradation.