| Pharmaceuticals and personal care products arechemicals whichdefined not according to their chemical structure but their purpose.As a "new type of pollutant ",PPCPs have received increasing concern recently.Ketoprofen(KET),a typical kind of PPCPs,with antipyretic,analgesic,anti-inflammatory and other effects,is widely used in the treatment of rheumatoid arthritis,osteoarthritis,arthralgia,spondylitis,non-rheumatic or postoperative pain.In the list of essential drugs publishedby World Health Organization,KET is one of the most important over-the-countermedicines.China's annual use of KET is more than 100 tons.Due to its direct or indirect discharge.KET is extensively detected inenvironmental water and drinking water.Normally,the concentration is in the order of ?g/L~ng/L.Ketoprofen that discharged into natural water body may cause potential danger ofbiological accumulation in the organism.The conventional waste water treatment plant is not able to remove this type of contaminant completely,remaining ketoprofen will enter enter the stage of drinking water disinfection.This unexpected pollutant will react with disinfectant in drinking water disinfection and the degradation dynamics,degradation products and toxicity are unknown.Ozone is a green,clean,environmentally friendly advanced oxidant.It has high oxidative ability,and also has property to generating stronger oxidant hydroxyl radical.It could remove thesmell of water,bacteria,pathogens and other microorganisms.In addition,it could remove most of the refractory organic matter.Therefore,it is currently substantially applied in the field of drinking water disinfection.The aim of this study was to investigate the degradation behavior of ketoprofen,and to provide the basis for evaluating its degradation effect and ecological risk.In the first part of the article,the kinetics of ketoprofen under the ozone system were determined by studying the degradation regularity of ketoprofen.The effects of the initial concentration of reactants,the initial p H value of the reaction solution,the flow rate of ozone and the reaction temperature on the reaction rate of ketoprofen were investigated.The radical quenching experiments and competitive experiments were conducted to determine the degradation mechanism of ketoprofen in the reaction system and the reaction rate constant of ketoprofen with each oxidation group.The intermediates were identified by UPLC/MS/MS.Furthermore,the toxicity of ketoprofen was evaluated and the removal rate of TOC was determined.The result indicated that the degradation of ketoprofen by ozone under different experimental conditions fitted first order kinetics well.The increase of initial p H value,QO3 and reaction temperature would enhance the degradation of KET,while the increase of C0 had the reverse effect.In this system,the present of O3 and ·OH had an oxidative effect on KET,where O3 was the dominant effect.The secondary reaction rate constants of ketoprofen were 1.09 L/(mol·s)with O3,and 8.82×109 L/(mol·s)with ·OH.During the process of ketoprofen degradation,20 major by-products were generated,higher risk of intermediates were involved.The second part investigated the effect of different forms of inorganic nitrogen ions on the degradation rate of ketoprofen and mechanism.The degradation products of ketoprofen under the presence of NO3-were identified and the toxicity of the product was evaluated.The results showed that NO2-had inhibitory effect on the degradation of ketoprofen,while NO3-and NH4+ promoted the degradation of ketoprofen,and the promotion of NO3-was stronger than that of NH4+.Six degradation products were identified,which contained three nitrogen-containing products.ECOSAR software was applied to evaluate the acute toxicity and chronic toxicity of KET and 6 products to fish,Daphnia magna and Chlorella,respectively.And the results showed that the products produced a larger toxicity than the parent. |
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