Evaluation of matrices for activated carbon adsorption and persulfate oxidation of trichloroethylene

• Main Authors: Wu-Hang Shin, 石武航
• Other Authors: Chen-Ju Liang
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/17333120871761991013

碩士 === 國立中興大學 === 環境工程學系所 === 96 === Chlorinated solvents such as trichloroethylene (TCE) have been widely used in industry. TCE is a dense non aqueous phase liquid and volatile organic compound. When TCE is accidently released in subsurface environment, the natural characteristics of TCE denotes that it could cause extensive groundwater contamination. Among a variety of subsurface remediation techniques, a permeable reactive barrier (PRB) is a permeable zone containing or creating a reactive treatment area oriented to intercept and remediate a contaminant plume. The reactive media such as activated carbon is commonly selected to absorb the pollutants from the groundwater. However, if the activated carbon reaches its adsorption capability, the PRB needs to be rebuilt with new materials or the carbon requires regeneration. Alternatively, in situ chemical oxidation (ISCO) is a remediation technology used to aggressively clean up contaminated area, mostly applicable to a highly concentrated contamination. The persulfate anion is an ISCO oxidant, which can be thermally or chemically activated to generate sulfate radicals for the destruction of organic contaminants. The objectives of this study were to evaluate the potential of the activated carbon PRB in conjunction with ISCO in treating TCE contamination. The results reveal that persulfate degradation in the presence of activated carbon follows a pseudo-first-order degradation kinetic model and the quantity of carbons is a rate-limiting factor. The surface of activated carbon after contacting with persulfate exhibits significant changes including the increase of surface acidity, the decrease of specific surface area and pH of the point of zero charge and also the reduction of adsorption capacity. Furthermore, persulfate degradation in the presence of TCE and activated carbon appears even slower. The TCE degradation mainly occurred in aqueous phase in the persulfate/activated carbon system. Moreover, when persulfate and iron activated persulfate are used to regenerate activated carbon, the results demonstrate that persulfate oxidation can induce desorption of TCE from carbon surface while iron activated persulfate can simultaneously undergo desorption and oxidization of TCE.