Application And Mechanism Of Highly Efficient Persulfate Activation Process In Pharmaceutical Wastewater Treatment

With the development of industry and the improvement of living standards,pharmaceuticals are widely used and flow into the water and soil environment.Although only trace or ultra-trace pharmaceuticals were observed in the environment,their long-term accumulation will undoubtedly cause potential harm to the biological and ecological environment.Persulfate advanced oxidation technology exhibits well pharmaceuticals wastewater treatment efficiency,while traditional persulfate activation means with some limitations such as high energy consumption and secondary pollution should be optimized and innovated.In addition,the difference in the degradation mechanism of persulfate technology applied to different pollutants is still unclear,thus the practical application of persulfate oxidation technology still faces challenges.In view of the above problems,this paper optimizes the persulfate oxidation technology and studies the differences in the degradation mechanism of different pollutants in the unified system.The main research contents are as follows:1.For solving the secondary pollution caused by transition metal,Co₂P was used instead of traditional transition metal to activate peroxymonosulfate（PMS）.Experimental results showed that divalent cobalt ions on the surface of Co₂P could react with PMS to generate active oxidation species such as hydroxyl radicals（·OH）and sulfate radical（·SO₄^-）,which could further degrade 98%of carbamazepine（CBZ）within 10 min.2.A piezoelectric BaTiO₃/Mo S₂（BTO/MS）heterojunction was constructed to inhibit the recombination of electron-hole pairs,which was beneficial to the activation of peroxymonosulfate（PMS）for the removal of ornidazole（ORZ）.Experimental results showed that the highly efficient charge separation in the piezoelectric heterojunction of BTO/MS promoted the activation of PMS,resulting in the synergy of pizeocatalysis and PMS oxidation during the process of ORZ degradation.The optimal ratio of BTO/MS for ORZ degradation under piezo/PMS process was 62.1 and 2.0 times higher than that of（BTO/MS）/PMS and（BTO/MS）/piezo processes.3.Three kinds of TCs[tetracycline（TC）,oxytetracycline（OTC）,and doxycycline（DTC）]with similar structure were chosen as the target molecules to investigate the effect of hydroxyl substituents on the degradation of TCs in a unified persulfate activation system[carbon black（CB）-activated peroxydisulfate（PDS）oxidation process].The degradation ratios of the TC,OTC,and DTC in the CB/PDS oxidation process followed the order of DTC>OTC>TC within 40 min.According to the density functional theory calculations,degradation products and pathways analysis,sites and numbers of the hydroxyl groups in TCs can affect their degradation efficiency and pathways,whereas the different degradation pathways may result in the different efficiency of TCs.Through optimizing the activation method of persulfate,this research improved the degradation efficiency of organic pollutants,which expands the application prospects of persulfate advanced oxidation technology.In addition,this research further investigated the role of substituents in pollutants degradation,which could provide some useful information for predicting the reactivity,potential fate and effect of pollutants in the aquatic environment.