Study On The Efficiency And Mechanism Of UV/Oxone Degradation Of Trimethoprim And Paracetamol

Pharmaceutical and personal care products（PPCPs）can change in the earth’s biochemical cycle,affect the sex ratio of higher organisms,alter plant growth,prevent larvae from hatching,body deformities and malignant tumors.As a new type of pollutant,PPCPs is a potential hazard to ecological environment and human health.Because of their complex structure,high toxicity,difficult biodegradation and environmental persistence,the traditional water treatment process is difficult to remove them.At present the degradation of PPCPs has become one of the hot issues in drinking water treatment in China.As a pretreatment process,Advanced oxidation processes（AOPs）has the advantages of highremovalefficiency,wideapplicationandlowselectivity.WaterPrince（2KHSO₅·KHSO₄·K₂SO₄,Oxone）has been widely used as a non-chlorinated disinfectant in enterprises and waterworks to produce a large amount of SO₄^·–,·OH and other active substances under UV irradiation.under neutral conditions,the standard oxidation potentials of SO₄^·–and·OH:2.5³.1V and 1.8².7V,respectively.UV/Oxone is a comprehensive oxidation system containing Oxone,SO₄^·–,·OH and other active substances.This convenient,energy-saving green oxidation technology UV/Oxone is a promising new advanced oxidation process.In this study,two typical PPCPs,trimethoprim（TMP）and paracetamol（ACE）were selected as the degradation objects of UV/Oxone process.The effects of different processes on the degradation of TMP and ACE,the reaction kinetics and the contribution rate of the active substances in the system were compared.The effects of various factors(concentration of oxidant,water background,temperature,Cl^-,NO₃^-,CO₃^2-,pH)on the removal efficiency were also discussed and elimination of chlorination disinfection By-product（DBPs）potential.By compared the effects of different processes on the degradation of TMP and ACE by different processes,it is fully proved that UV/Oxone produces SO₄^·–,·OH and other active substances,which can efficiently degrade TMP and ACE.The degradation rates are increased by 15.06%and 37.93%,respectively.The degradation equation is in accordance with the pseudo-first-order kinetic equation:k=0.8910min^-11 and k=0.4135min^-1.When the amount of oxidant Oxone was increased,the efficiency of the degradation system was increased.From the mathematical model analysis,it is concluded that the contribution rate of SO₄^·–,·OH is more than that of SO₄^·–in alkaline condition.under acidic conditions,SO₄^·–exhibits stronger specificity and oxidation.Cl^-promoted the degradation of TMP and ACE;The low concentration of NO₃^-promoted the degradation of TMP and ACE,and the high concentration of NO₃^-inhibited the degradation of TMP and ACE;CO₃^2-inhibits the system.Compared with neutral condition,the condition of weak acid/weak base is more favorable to the degradation of TMP and ACE.The effect of Br^-concentration on the potential of chlorination to generate DBPs in the degradation of TMP and ACE by UV/Oxone was the most significant.The formation of THM was inhibited by a certain amount of Br^-.This paper provides a systematic theoretical basis and technical support for studying the mechanism and efficiency of PPCPs.