Degradation Performance And Mechanisms Of Ibuprofen From Water By Ultraviolet-activated Percarbonate Technology

Sodium percarbonate（SPC）is a novel oxidant,which is a potential alternative to hydrogen peroxide.It has the advantages of high efficiency,non-toxicity,economy,and environmental friendliness.In recent years,SPC has been used in water treatment by using advanced oxidation processes（AOPs）.In this paper,a novel AOPs based on ultraviolet（UV）-activated SPC was constructed,and laboratory experiments were carried out with ibuprofen（IBP）as the representative pollutant;the degradation kinetics model of IBP was established;the response surface methodology（RSM）method was used to optimize the key parameters which affect the degradation of IBP;the relative contribution of reactive oxygen species such as hydroxyl and carbonate radical in the degradation of IBP were evaluated;the toxicity of UV/SPC technology to degrade IBP was determined,and the treatment cost was calculated.The result showed that UV/SPC technology can degrade IBP efficiently and IBP can be completely degraded in 30 min.Moreover,the degradation effect of IBP was less affected by p H value（4.05-8.03）,which indicated that UV/SPC technology was applicable in a wide range of p H values.The RSM optimization indicated that IBP degradation rate could reach 97.26%with 5μM of IBP,40μM of SPC,p H value of7.60,and UV irradiation for 20 min.The presence of humic acid,fulvic acid,and high concentration of HCO₃^-,and wastewater quality were not conducive to the degradation of IBP.Scavenging experiments of free radicals and electron paramagnetic resonance analysis indicated that hydroxyl radical played a major role in the UV/SPC degradation of IBP,while carbonate radical contributed less.Six degradation intermediates of IBP were detected by GC-MS,and it was speculated that the primary degradation pathways were hydroxylation and decarboxylation.In addition,benzene-opening products of IBP were detected,indicating that the UV/SPC system can deeply oxidize IBP.The acute toxicity test based on Vibrio fischeri indicated that the toxicity of the reaction system reduced by 11%when the degradation time was 50 min.The lower electrical energy per order(3.57 k Wh m^-3)indicated that the UV/SPC process was cost-effective in the degradation of IBP.The above results showed that the degradation of IBP by UV/SPC technology had the advantages of high efficiency,economy,and environmental friendliness.This paper expands and enriches the research field of water pollution control,and also provides the theoretical support for the application of UV/SPC technology to practical water treatment.