Heterogeneous Activation Of Peroxymonosulfate And Application For The Degradation Of Organic Pollutants

Developing an efficient and green catalytic oxidation technology always is a challenge in the field of environmental catalysis.Due to its stability,environmental friendliness,cost-effectiveness,good water solubility(>250 g L^-1 at 20°C)and ease of transport and storage,the advanced oxidation technology based on monopersulfate?PMS?has attracted more and more attention.The most efficient catalyst for the activation of PMS has been demonstrated to be Co-based catalysts.However,cobalt leaching is a barrier to its practical application.Therefore,the development of stable and efficient heterogeneous catalysts for the activation of PMS is of great importance.In this thesis,we investigated the performances of the catalysts including magnetic nanomaterials Fe₃C/NC and BiOBr with micro-nano structure for the activation of PMS to degrade organic pollutants.The main research work was as follows.?1?Magnetic Fe₃C nanoparticles on N-doped carbon?Fe₃C/NC?were prepared by sol-gel combustion method with ferric chloride hexahydrate as metal precursors,melamine as a carbon source and hexadecyltrimethylammonium bromide as a template.As characterized,the Fe₃C/NC nanoparticles were composed of the sheet-like structure of NC and NC capsulated Fe₃C on the sheet.The Fe₃C/NC nanoparticles were employed as an efficient catalyst for PMS activation to generate sulfate radicals(SO₄^·-),single oxygen?¹O₂?and hydroxyl radicals?·OH?to degrade ibuprofen?IBU?.The added IBU(10 mg L^-1)was almost completely removed in 60 min by using 0.1 g L^-1 Fe₃C/NC and 2 g L^-1 PMS.The catalyst was confirmedtohavegoodabilityandexcellentreusability through leaching measurements and cycle experiments.A catalytic mechanism involving the action of both Fe₃C reactive sites and N-doped carbon matrix in Fe3C/NC was proposed on the basis of XPS analysis and other characterizations.Fe3C was identified as reactive sites for the activation of PMS and the generation of·OH and SO₄^·-,while NC in Fe₃C/NC catalysts induced the generation of ¹O₂ through the activation of PMS.Moreover,the degradation pathway of IBU in the Fe₃C/NC-PMS system was proposed according to the detection of degradation intermediates.?2?The feasibility that BiOX?X=Br,Cl,I?as an efficient catalyst for PMS activation to degrade organic pollutants was studied.Under the same experimental conditions,BiOBr exhibited stronger activity for activation of PMS than BiOCl and BiOI.The added RhB?20?M?was almost completely removed in 6 min by using0.2 g L^-1 BiOBr and 0.5 mM PMS.As the dosage of PMS increased to 2 mM,the TOC removal rate of 69%can be achieved.The effects of catalyst load,reaction pH and PMS concentration were investigated on the catalytic activity of BiOBr.The quenching experiments and electron paramagnetic resonance technology?EPR?confirmed the generation of·OH as the major reactive species for the degradation of RhB.The oxidation ability of BiOBr-PMS,BiOCl-NaBr-PMS and Bi₂S₃/BiOBr-PMS system was compared.Based on the above results,a catalytic mechanism involving the action of Br^-reactive sites was proposed.The high-efficiency and good stability of the catalyst support that the catalyst has significant potentials for the application in the field of pollution control.