Study On The Degradation Of Two Typical Cardiovascular Drugs By Persulfate In Aqueous Solution

Atenolol(ATL)and atorvastatin(ATV)are two common cardiovascular drugs.Since the incidence of cardiovascular disease is increasing year by year,the use of cardiovascular drugs has greatly increased,making them inevitablly enter into the environment.In recent years,due to the continuous improvement of analytical instruments,cardiovascular drugs have been detected in effluent water,sewage sludge and surface water.Therefore,their potential harm to the ecological environment and human health is getting more and more attention.The existing methods for treating cardiovascular drugs include adsorption,biodegradation,Fenton oxidation,ozone oxidation,electrochemical oxidation,and photodegradation.However,the drawbacks of these treatment techniques limited their wide application.In recent years,advanced oxidation methods based on sulfate radicals(SO4-·)have been extensively studied to remove organic contaminants in wastewater.Compared to hydroxyl radicals(·OH),SO4-· have a wide range of pH adaptation,high mineralization capacity,long half-life and high oxidation potential.The degradation of ATL and ATV by two sulfate radical systems were investigated in this thesis.The main research conclusions are as follows:(1)Study on the mechanism of ATL degradation by Heat/PS.The degradation rate constants of ATL increased significantly from 1.4×10-3 to 9.33×10-2 min-1 as reaction temperature elevated from 40 to 70?.Temperature dependence of the kinetic constant was further evaluated using the Arrhenius equation.The activation energy(Ea)of ATL was thus determined from the linear relationship between In kobs and 1/T to be 112.6 kJ/mol.As PS dosage increased from 0.1 to 0.9 mmol/L,the degradation rate constants increased from 2.1×10-3 to 1.85×10-2 min-1.The optimal ATL degradation rate was obtained at pH 5(1.4×10-2 min-1),followed by 3(1.28×10-2 min-1),7(1.18×10-2 min-1),9(7.5×10-3 min-1),and 11(6.3×10-3 min-1).NO3-and Cl-had little effect on the degradation of ATL,while the inhibitory effect of HCO3' and SRFA were obvious.SO4-· and ·OH were both responsible for the degradation of ATL,and SO4-· played a more important role.Eight transformation intermediates were formed through four degradation pathways and they were further degraded as the increase of activation temperature and PS concentration.The high TOC removal ratio of ATL and PS consumption proved that heat activation of PS is a promising method to mineralize ATL.(2)Study on mechanism of ATV degradation by CuFe2O4/PMS.The results showed that at pH 7,[PMS]-25 ?mol/L,[CuFe2O4]=40 mg/L,10 ?mol/L ATV was completely removed after 15 min.The morphological and size changes of CuFe2O4 before and after reaction were characterized by SEM and TEM.No significant changes were found.XPS technique was used to analyze the valence changes of Cu and Fe on the surface of CuFe2O4 before and after the reaction.The results showed that both of them participated in the activation of PMS.SO4-· and ·OH were both responsible for the degradation of ATV,and SO4-· played a more important role.Based on the eight products identified by TOF-LC-MS,four degradation pathways of ATV were inferred,including lactonization,hydroxylation,deamidation and pyrrole ring cleavage.P541(ATV lactone),P557(hydroxylated ATV lactone)and P416(the pyrrole ring-open intermediate)are the main intermediates in three different PMS concentration systems.The degradation of ATV in actual wastewater is mainly influenced by organic matter rather than inorganic ions.At 100 mg/L CuFe2·4 and 3.0 mmol/L PMS,the TOC removal efficiency of ATV in ultra-pure water and in actual wastewater was 61.72%and 18.9%,respectively.At the same time,PMS is almost consumed in both systems.The above studies have shown that activated persulfate has a good potential for the removal of cardiovascular drugs,and can completely remove cardiovascular drugs in water within a relatively short period of time with appropriate activation temperature or copper ferrite dosage.Through further research on actual wastewater treatment technology conditions,it is expected to provide a new approach for the efficient removal of cardiovascular drugs and emerging pollutants.