Design And Mechanism Of Material System For The Removal Of Refractory Organic Pollutants In Water By Catalytic Activation Of Monoperoxosulfate

Water is the foundation for life and development,and achieving sustainable development of global water resources is a common goal worldwide.However,water pollution is severely threatening the human health.Development of highly efficient water treatement process is urgent.Heterageneous catalytic PMS activation of the pollutant degradation is an emerging advanced oxidation process.PMS based AOP is a promising approach toward efficient water treatment,and therefore attracted intensive research interest.However,the low catalytic activity and poor cycle stability impeded the application of PMS base AOP in water treatement.Development of novel catalytic system,and detailed mechanistic understanding on the structure-activity relationship were critical to the realization of highly efficient water treatment reaction system.In this thesis,two efficient catalytic reaction systems were developed,which were able to efficiently degrade a series of recalcitrant organic pollutants.Meanwhile,the rationale behind the high catalytic activity were investigated via systematic probe reactions and spectroscopy techniques.（1）Nanoconfined cobalt nanocrystals for PMS activation and mechanism investigations.Polymerization of dicyandiamide with formaldyhyde in the presence of Co ions affords a precusor with uniform distribuition of Nitrogen coordinated Co.By pyrolysis reaction under high temperature,the cobalt nano-crystals were encapsulated in the in situ formed nitrogen doped carbon nano-tube（Co-NC）.With SEM,TEM,XRD,and XPS techniques,the physiochemical properties have been analysed,and the nanocomfinement structure was confirmed.Co-NC was efficient in catalytic activation of PMS for the elimination of a series of pollutants.Systematic mechanistic investigations demonstrated that the mediated electron transfer mechanism was governing the pollutants degradation process on Co crystals under nanoconfinement.The reaction system exhibited remarkable resistance towards humic acid,and mineral ions in water.What’s more,due to the encapsulation structure,cobalt leaching was very low,and the catalyst showed good cycle stability.（2）Fe single-atom catalysed PMS activation for pollutant degradation and mechanistic studies.The single-atom catalyst(Fe _SA-NC)was synthesized via the distribution of Fe ion in the self-assemly of melamine and citric acid followed by pyrolysis under high temperature.Via XRD,XPS,and XAFS,the structure of single Fe atom distributed in the nitrogen-doped carbon matrix was revealed.Fe _SA-NC exhibited efficient catalytic performance in pollutants degradation by PMS activation.In this reaction system,the natural organic maters and the mineral ions posed negligible impact on the catalytic activity of Fe _SA-NC.By continuous flow reactor,Fe _SA-NC showed good stability and pollutant elimination performance in the presence of PMS.Detailed probe reactions as well as spectroscopy investigations indicated that the mediated-electron transfer mechanism was play the dominant role in the PMS activation for pollutants degradation.The findings and conclusions in this thesis could shed light on the design of highly efficient catalytic reaction system for water treatment via PMS based AOP process.