Mechanism Analysis Based On Peroxomonosulfate Catalyzed Activation And Its Application In Degradation Of Organic Pollutants

In recent years,the advanced oxidation processes?AOPs?based on the catalytic activation of peroxymonosulfate?PMS?attracted more and more attention in the treatment of organic wastewater because of their strong oxidizing ability to achieve efficient degradation of pollutants.The PMS-based AOPs may be devided into two groups according to the reaction mechanism:one involes the generation of radical active species,and the other involves a non-radical activation mechanism.It is generally considered that carbon catalysts can activate PMS to degrade organic pollutants through non-radical process,while transition metals mostly acivate PMS through a radical process.Therefore,the present thesis investaged two different PMS-based AOPs.The details were shown as the following.?1?A composite of Fe/Fe₃C and N-doped graphitic carbon?Fe/Fe₃C@NG?was prepared and used as a catalyst for the activation of PMS toward the oxidative degradation of Norfloxacin?NOF?.It was observed that Fe/Fe₃C@NG behaved as a bifunctional material,showing both good adsorption ability and catalytic activity.The maximum adsorption capacity of Fe/Fe₃C@NG for NOF was evaluated as 0.13 mmol g^-1.Under given conditions(NOF concentration 0.1 mmol L^-1,catalyst load 0.1 g L^-1and PMS addition 1 mmol L^-1),the degradation of NOF was almost completely achieved in 30 min with a degradation rate constant of 0.22 min^-1.A non-radical mechanism was proposed for the activation of PMS by Fe/Fe₃C@NG by the by the scavenging test,EPR and chronoamperometry analysis.The fast and complete degradation of NOF was achieved via a rapid electron transform,in which both PMS and NOF molecular were adsorbed on the surface of Fe/Fe₃C@NG and PMS was activated by obtained the electron from NOF to oxidize NOF.?2?The preparation method of MnCo₂O₄ catalyst was proposed,and by using this method MnCo2O4 was prepared as a catalyst.The SEM,TEM,XRD and XPS characterization showed that the morphology of the product was uniform and the microsphere structure was composed of many small particles.It was found that the prepared MnCo₂O₄ effectively activated PMS with the generation of SO₄^·-to degrade the target pollutant BPA.Under given conditions(BPA concentration 20 ppm,catalyst load 0.1 g L^-1 and PMS addition 0.5 mmol L^-1),the degradation of BPA followed the first-order kinetic model and almost completely achieved in 15 min with a degradation rate constant of 0.19 min^-1.Radical scavenging test confirmed that SO₄^·-radicals play a leading role in the degradation of BPA at the MnCo2O4+PMS system.XPS characterization results of the fresh and used MnCo₂O₄ indicated the highly catalytic activity could be attributed to a catalytic mechanism involving both Co and Mn in MnCo2O4.Based on the research,we proposed the radical mechanism of MnCo₂O₄ catalyzed activation of PMS to produce SO₄^·-.