Study On Removal Of Micro Persistent Pollutants From Water By Advanced Oxidation Technology Based On UV

After preliminary experimental discussion,literature search,and pre experimental screening,this study determined to take ultraviolet/persulfate（UV/PDS）as the degradation system,combined with simulation analysis and quantum chemical calculation,to explore the degradation kinetics and reaction mechanism of acyclovir（ACY）and atenolol（ATL）in the UV/PDS process.After reaction of ACY and ATL in the UV/PDS process at p H=6.0 for 30 min,their removal rate and apparent degradation rate constant(k_app)were greater than 94.8%and0.0931 and 0.1938 min^-1,respectively,which was higher than the removal efficiency of single UV light source irradiation(0.001 min^-1)or PDS combined oxidation process(0.001 min^-1).In order to verify the main active substances in the degradation of ACY and ATL in the UV/PDS system,radical quenching experiments and electron paramagnetic resonance（EPR）were carried out.Hydroxyl radical（^·OH）and sulfate radical(SO₄^·-)have been proved to be the main reactive radicals.Through competitive kinetics and calculation,the second order reaction rate constants of reactive radicals with ACY and ATL under different p H conditions were determined to be 1.30-1.50 and 3.45-4.60 M^-1s^-1 and 1.00-1.58 and 4.56-5.64 M^-1s^-1,respectively.In order to further verify the reliability of the experimental data,the kinetic software Kinetic was used to simulate and correct the degradation process of ACY and ATL as well as the degradation under the influence of different PDS doses,p H and anions.Based on the active sites predicted by Fukui function and the intermediates of ACY and ATL identified by UPLC-QTOF-MS,the possible transformation pathway of ACY and ATL in the process of UV/PDS was proposed.By comparing different oxidation systems,the combined UV/Chlorine/O₃ oxidation process based on UV has been proven to have good removal effects for trace pollutants.In this experiment,a water treatment method based on UV/Chlorine/O₃ multicomponent synergistic oxidation was established.After reacting for 10 minutes under p H=6.0 in the UV/Chlorine/O₃process,the removal rate and apparent degradation rate constant（kobs）of p CBA were greater than 96.7%and 0.251 min^-1,which had a higher removal rate than irradiation with a single UV light source(0.231 min^-1),O₃ oxidation alone(0.071 min^-1),Chlorine/O₃(0.089 min^-1),UV/Chlorine(0.117 min^-1),and O₃/UV(0.093 min^-1).The effects of factors such as Na Cl O dosage,pollutant concentration,p H value in water,and wastewater substrate on the degradation of p CBA by UV/Chlorine/O₃ were studied.The degradation process was in accordance with pseudo first order reaction kinetics（R²>0.96.5%）.The kinetic simulation software Kintecus verified the reliability of the experiment.Moreover,the contribution rates of direct UV and various free radicals at different p H were investigated through free radical inhibitors.Due to the generation of disinfection by-products（DBPs）in advanced oxidation systems containing chlorine,the degradation process of p CBA in UV/Chlorine,Chlorine/O₃,and UV/Chlorine/O₃systems was investigated,and the generation of two types of DBPs was confirmed,namely dichloroacetone（DCP）and dichloroacetonitrile（DCAN）.