Removal Of Tetracycline By Activating Peroxymonosulfate With MoS₂ Composite

At present,there are numerous cases of negative effects of serious antibiotic pollution on water environment and human health.Therefore,it is very important to strengthen the research on the efficient process of removing antibiotics from water environment.In recent years,a variety of water treatment technologies have emerged one after another,such as membrane filtration,biological treatment,advanced oxidation technology and so on.Each technology has its own advantages and disadvantages.For antibiotic wastewater,a fast,thorough,simple and efficient treatment method is needed.Advanced oxidation technology is a widely used technical route in recent years,in which transition metal activated persulfate（PS）Fenton oxidation has become a research hotspot because of its fast reaction speed,high removal rate,low cost,less pollutants and so on.In this study,molybdenum（Mo）,nanometer zero-valent iron（nZVI）and cobalt（Co）were used to prepare trimetal composite catalysts to activate peroxysulfate（PMS）to remove tetracycline（TC）pollutants.The specific research contents and conclusions are as follows:The main results are as follows:（1）Two kinds of nano-molybdenum disulfide(MoS_2（CR）and MoS_2（CM）)with different structures were synthesized by chemical method and hydrothermal method.Using these two kinds of molybdenum disulfide carriers,nZVI and Co were doped and deposited on the surface of molybdenum disulfide by liquid phase reduction method,nZVI/Co@MoS_2（CR）and nZVI/Co@MoS_2（CM）composites were successfully prepared.（2）The four composites of MoS_2（CR）,MoS_2（CM）,nZVI/Co@MoS_2（CR）and nZVI/Co@MoS_2（CM）were characterized（SEM,XRD,XPS,BET,FT-IR）.The results show that the structure of MoS_2（CR）synthesized by chemical method is similar to that of coral reef,and that of MoS_2（CM）synthesized by hydrothermal method is similar to that of camellia,forming mesoporous structure.After loading nZVI and Co,the morphology and structure of the two composites nZVI/Co@MoS_2（CR）and nZVI/Co@MoS_2（CM）did not change significantly.nZVI and Co were distributed inside and outside the mesopores of MoS₂ in the form of ions and flake particles.（3）Four transition metal composites MoS_2（CR）,MoS_2（CM）,nZVI/Co@MoS_2（CR）and nZVI/Co@MoS_2（CM）were used to activate PMS to degrade TC.The experimental data show that the trimetal composites nZVI/Co@MoS_2（CR）and nZVI/Co@MoS_2（CM）have higher removal efficiency and removal rate of TC.Based on the analysis of the degradation mechanism,the synergistic effect of unsaturated S and highly active Mo（IV）centers and the interlayer band gap structure of MoS₂ also greatly accelerated the electron transfer rate,which effectively promoted the cycle of different valence Fe ions and different valence Co ions,thus accelerating the reaction rate.The results of quenching experiments show that superoxide radical（O₂^-）and singlet oxygen（1O₂）play an important role in the degradation efficiency of TC in trimetal composite nZVI/Co@MoS_2（CR）and nZVI/Co@MoS_2（CM）activated PMS system.According to LC-MS analysis,five possible degradation pathways of TC were proposed.