Abiotic reductive degradation of carbon tetrachloride in improving the contaminated groundwater

• Main Authors: Chang,Shuh-Kuen, 張樹坤
• Other Authors: Wu,Shian-Chee
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/11443224866139234098

碩士 === 國立臺灣大學 === 環境工程研究所 === 84 === Groundwater is an important water resource. In this study, flow- through column experiments were conducted to investigate the reductive degradation of carbon tetrachloride(CT) while Vitamin B12 and humic acid were used as catalysts and titanium (III) citrate, dithiothreitol(DTT) and ferrous iron were used as reducing agents. We would probe into the influence of catalyst, reducing agent, flow and pH on the degradtioin and find out the difference between the results of column tests and model simulations. According to the results of this study, the degradation rate of carbon tetrachloride(CT) was very slow without any catalyst in the column tests, and the dimerization of carbon tetra- chloride(CT) to form hexachloroetane could not be found in this system. In the system using Vitamin B12 as a catalyst,titanium (III) citrate was a better reducing agent than dithiothreitol (DTT) and ferrous iron, and it was controlled by the formation of Vitamin B12s. After the passage of approximately 10 pore volumes of solution, the concentration profile was considered to be at steady state. In the system using humic acid as a catalyst, titanium(III) citrate could reduce carbon tetra- chloride(CT) to dichloromethane(DCM), but the other reducing agents could not. According to the results of varying flow, CT in a high flow system had shorter half-life than a low flow system, and it might be related to the intensity of mixing.In the flow-through column tests of different pH, it was found that the system with high pH has shorter half-life than system the with low pH. Di- chloromethane(DCM) was produced more than chloroform(CF) in a high pH reduction system, and it was resulted from the higher redox potenital of titanium(III) citrate.