Study On Degradation Of Typical PPCPs In Environment By Ozone-based Advanced Oxidation Technology

Pharmaceutical and personal care products?PPCPs?have been widely detected in surface water,groundwater and drinking water in recent years,which has attracted the attention of many scholars.PPCPs have a negative impact on the environment and human health during long-term exposure to water.Advanced Oxidation Processes?AOPs?,as novel treatments of efficient removal of PPCPs,there are some gaps in the mechanism studies involved.In this paper,ketoprofen?KET?was used as the target pollutant,and its degradation process under ozone and peroxymonosulfate?O3/PMS?was studied.Furthermore,under the simulated sunlight,the degradation of ciprofloxacin?CIP?by ozone and photocatalysts?TiO2/CDs?was studied,the reaction kinetics and mechanism of the process were illustrated as well.The main research results are as follow:The simulated ketoprofen?KET?wastewater was oxidized by ozone?O3?and ozone combined with peroxymonosulfate?O3/PMS?in this chapter.The removal effect of KET in both systems and the influence of initial pH values,as well as the degradation mechanism were investigated.Results indicated that the degradation of KET obeyed pseudo-first order kinetics.PMS could dramatically accelerate the process of ozonation of KET with a promoting ratio of 58.61%.In addition,the degradation of KET in both systems were significantly affected by initial pH value and higher pH value would bring better degradation effect.In the meantime,research found out that pH decreased as the experiment processed.It has been proved that both O₃,·OH and SO4^·—simultaneously contributed to KET degradation in O3/PMS,under the setting conditions,the contribution were 4.35%?54.35%?41.30%.The mechanism of O3/PMS was proposed detailedly.In this chapter,the objective was mainly focusing on the mechanism investigation of ciprofloxacin?CIP?degradation by photocatalytic ozonation process which carried out by ozone and TiO2 with a low content of carbon-dots?CDs?under simulated sunlight irradiation.The physicochemical properties of the prepared photocatalysts were characterized by X-ray diffraction?XRD?,transmission electron microscopy?TEM?,scanning electron microscope?SEM?X-ray photoelectron spectroscopy?XPS?and zeta potential.Comprehensive investigation has proven the process to be efficient in the removal of CIP with high yield of reactive species(·OH,O2^·—,h⁺,etc.).Kinetic model on pH investigation found out a repulsive force between the photocatalysts and CIP intensified with the increasing pH,so did the production rate of hydroxyl radicals?·OH?,while eventually reached a balance and achieved a maximum degradation rate.The results indicated that the enhancement mechanism was triggered by the photoexcited electron accumulated on CDs and transferred by ozone,resulting in the continuous generation of h+,O3^·—and O2^·—.Possible photocatalytic ozonation degradation pathways of CIP were proposed according to the identifications of intermediates using high-resolution accurate-mass spectrometry?HRAM?LC-MS/MS.