Efficient Degradation of Organic Dye Acid Red G by UV185 Combined with Periodate
Dyes are widely used in various industries and are important water pollutants.In recent years,UV-based advanced oxidation technologies have attracted considerable attention in the dye wastewater treatment industry.In this study,the reaction mechanism of UV185 combined with a periodate(PI)homogeneous advanced oxidation system for the removal of acid red G(ARG),which is a typical azo dye,was investigated.UV185 can crack aquatic living oxidant species;UV185 as a lamp source not only retains the advantages of UV254,but also efficiently degrades organic pollutants in water.The experimental results showed that when the dosage of PI was 0.5 mmol∙L-1 and the initial concentration of ARG was 50 mg∙L-1,the removal rate of ARG in photolysis reached 98.17%in 4 min,and the reaction process was in accordance with the kinetic model of the first-stage reaction,with r2>0.990.The system maintained a high ARG removal rate under acidic and neutral conditions and significantly inhibited ARG degradation under alkaline conditions at pH values.HCO3-and Cl-inhibited the system,NO3-slightly promoted the system,SO42-had almost no effect on the reaction rate,and humic acid strongly inhibited ARG degradation.The results of free-radical trapping experiments and electron paramagnetic resonance tests showed that the active substances in the system were·OH,IO3·,IO4·,and 1O2.The TOC results showed that the 30 min TOC removal was 67.9%,which was higher than the mineralization of both hydrogen peroxide(H2O2)and persulfate(PDS)at the same concentration of conventional oxidants combined with photolysis alone and UV185.Based on UV-visible spectral analysis,it was initially deduced that ARG degradation occurred mainly through azo bond breaking and naphthalene ring opening.Based on the experimental results of liquid chromatography-mass spectrometry(LC-MS),possible transformation pathways of ARG in the degradation process of the VUV/PI advanced oxidation system were proposed.
periodateacid red GUV185homogeneous advanced oxidationfree radicalsazo-bond
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