Enhanced Recovery of Trichloroethylene from Soil by Tween-80 Surfactant Added in the Electrolyte of Electrokinetic Approach

• Main Authors: Meng-Han Yeh, 葉孟翰
• Other Authors: Wing-Ping Liao
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/75459991921609875420

碩士 === 國立中興大學 === 環境工程學系所 === 100 === The chlorinated organic solvents have been widely used in the industry in Taiwan for over the past two and three decades. Trichloroethylene is among the most ubiquitous chemicals found in groundwater and soil contaminants. Trichloroethylene’s properties is specific gravity greater than 1 and low solubility in water. It is a typical DNAPL(Dense Nonaqueous-Phase Liquid). When it is released into ground, it can be adsorbed in the unsaturated zone and migrated by gravity and diffusion into groundwater, causing subsurface pollution seriously. Electrokinetic (EK) remediation technology is recognized by the U. S. Environmental Protection Agency as one of the available techniques for remediation subsurface the DNAPLs pollution of clay soil site. For hydrophobic organic compounds is of the low solubility in water, therefore, the electrokinetic remove is not effective. The surface-active agent(surfactant) has the characteristics of high solubility of hydrophobic organic compounds. This study combined the advantages of electrokinetic and surfactant to remove contaminants of TCE from soil. In this study of adding surfactant in electrolyte to investigate the performance of trichlorethylene in the soil removal, using non-ionic surfactant Tween-80 as the operating fluid; the characteristics of which are low toxic, feasible for microbial decomposition and of low critical micelle concentration (CMC). The experiment will be divided into two parts, which are either different in concentrations of MgCl2 or in concentrations of Tween-80 solutions, for the electrokinetic effect of remediation trichloroethylene from soil. The results showed that the control group added only 0.005 M MgCl2 as the operating fluid, the removal rate was 16.8 %；Test 2 added 0.005 M MgCl2 in 50 mg/L Tween-80 solution, the removal rate was up to 36.8 % , and Test 3 added 0.05 M MgCl2 in 50 mg/L Tween-80 solution, the removal rate would be up to 60.1 % . When Tween-80 concentration increased to 100 mg/L, the removal efficiency of trichlorethylene is different. When the electrolyte concentration of MgCl2 was 0.005 M, the removal rate of only 15.7 %；the pore fluid could be blocked, because of the increasing adsorption capacity of soil while the concentrations of Tween-80 was 100 mg/L. When 0.05 M MgCl2 was used, the removal rate was 46.7 %；the quantity of electro-osmosis flow and the movement of micelles in the pore increased extremely by high current, leading to the moving of soil particales in the pore；and thus, drived the pore fluid with pollutants out of the soil.