Study On Degradation Of Triphenyl Phosphate In Water By Peroxymonosulfate Catalysis Based On Nano-Iron/Cobalt Modified Materials

In this paper,cobalt salt modified biochar（Co₃O₄/BC）and sulfidized nano-zerovalent iron（S-nZVI）were prepared by impregnation one-step pyrolysis and chemical synthesis respectively.Elementary analysis,nitrogen adsorption and desorption,FTIR,XRD,SEM-EDS,TEM and other characterization methods were used to analyze the structural properties of the self-made materials.Using triphenyl phosphate（TPHP）,a typical organophosphorus flame retardant with neurotoxicity as the target pollutant,the ability of two modified materials to activate PMS was degraded by monosulfate（PMS）.The thesis focuses on the effects of cobalt doping,sulfur doping and other factors on the structure and performance of materials and the mechanism of activating PMS to remove TPHP.First,the paper investigated the effect of Co₃O₄/BC preparation process conditions on the removal of TPHP by activated PMS.The results showed that Co₃O₄ can be successfully performed at a pyrolysis temperature of 450℃,a cobalt doping ratio of 1:20,and a pyrolysis time of 3 h.The Co₃O₄ is supported on the surface of biochar,and the particle size is uniformly distributed between 200 and 1000 nm.The specific surface area is the largest and the degradation effect is the best.Subsequently,the paper optimized the reaction conditions such as Co₃O₄/BC,PMS dosage and solution p H.In order to effectively distinguish the adsorption and degradation of TPHP during the removal process,a step-by-step experiment is designed in this paper to conduct in-depth research on the degradation of TPHP on Co₃O₄/BC.The results show that with the increase of the doping amount of cobalt,although the adsorption amount of TPHP on Co₃O₄/BC decreases,the ability of Co₃O₄/BC to catalyze the production of sulfate free radicals(SO₄^·-)by PMS increases more significantly.In the end,the degradation of TPHP on Co₃O₄/BC was significantly enhanced,so the removal effect of TPHP by the Co₃O₄/BC/PMS system was significantly improved.By means of liquid chromatography-mass spectrometry（LC-MS）,XPS,FTIR and the comparison of catalytic effects of different material systems,the mechanism of TPHP degradation by Co₃O₄/BC activated PMS was discussed.It was found that:firstly,TPHP adsorbed on the surface of Co₃O₄/BC material,and then SO₄^·-oxidative decomposition generated by Co₃O₄ activation,this is a cooperative process of adsorption and oxidative degradation,and the adsorption rate was higher than the oxidation rate.Based on LC-MS detection and analysis,TPHP degradation pathway mainly involves hydroxylation and phenoxy bond cleavage.Finally,the performance of degradation of TPHP by PMS activated by nano-zero-valent iron（nZVI）and sulfurized nano-zero-valent iron（S-nZVI）was compared.It was found that sulfurization can improve the electron transfer ability and surface hydrophobicity of nano-zero-valent iron,thereby improving the catalytic ability of the S-nZVI/PMS system.Compared with the nZVI/PMS system,the S-nZVI/PMS system improved the removal efficiency of TPHP by 20.1%.Based on LC-MS detection and analysis,the degradation pathway of TPHP by S-nZVI/PMS system was proposed.The development of this research will provide theoretical basis and technical guidance for the application research of advanced oxidation technology based on Co（Ⅱ）/PMS,Fe/PMS.