Combined Process of Microelectrolysis/Oxidation for Advanced Degradation of Trichloroethylene and 1,4-Dioxane
Trichloroethylene(TCE)is a typical pollutant which is widely distributed in groundwater and difficult to degrade.It has the properties of high density,strong migration ability,relatively durable and difficult to biodegrade.Common groundwater remediation techniques have the problems of low TCE removal efficiency and high cost.In addition,the associated pollution of chlorinated hydrocarbon stabilizer 1,4-dioxane(1,4-D)is often found in groundwater of most TCE contaminated sites and is difficult to be removed comprehensively.At present,the advanced oxidation technology based on persulfate is favored because of its high efficiency,economy and environmental friendliness,and is one of the most effective technologies to degrade organic pollution.In this study,a new microelectrolysis-oxidation coupling technology system(nZVI/C/CP-CA/PS)was constructed with iron carbon galvanic cell(nZVI/C)as activator,calcium peroxide(CP)as enhancer and citric acid/sodium persulfate(CA/PS)as oxidant to investigate the degradation of high concentration TCE in water.The effects of different remediation systems,dosage ratio,interval time and reaction temperature on the degradation of TCE were investigated,and the removal effect of the coupled system on TCE and 1,4-D composite pollution was initially explored.The results showed that:TCE with an initial mass concentration of 10 000 μg/L was treated by nZVI/C/CP-CA/PS coupling system for 6 h at room temperature of 20 ℃ for an interval of 3 h,and the molar ratio of activator nZVI/C,enhancer CP and oxidizer CA/PS was 35∶0.5∶26.The effluent concentration met the requirements of Class Ⅳ water in the Standard for Groundwater Quality(GB/T 14848-2017),and the removal rate was close to 100％.The degradation mechanism indicated that TCE was partially degraded by adsorption of activated carbon and reduction dechlorination of nZVI/C/CP enhanced primary cell.Then,CA/PS oxidants were further activated by the galvanic cell and its products to produce strong oxidizing free radicals such as·OH and SO4·-for deep degradation,thus further reducing the concentration of TCE,and the degradation process conformed to zero-order reaction kinetics.The experiment shows that nZVI/C/CP-CA/PS coupling system has dual advantages of high efficiency and economy for the degradation of high concentration TCE,and has great application potential in the restoration of TCE and 1,4-D complex contaminated sites,which is conducive to promoting the application and development of this coupling system in the organic contaminated water treatment industry.
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维普
