Mobilization of phenol and dichlorophenol in unsaturated soils by non-uniform electrokinetics.
The poor mobility of organic pollutants in contaminated sites frequently results in slow remediation processes. Organics, especially hydrophobic compounds, are generally retained strongly in soil matrix as a result of sorption, sequestration, or even formation into non-aqueous-phase liquids and their mobility is thus greatly reduced. The objective of this study was to evaluate the feasibility of using non-uniform electrokinetic transport processes to enhance the mobility of organic pollutants in unsaturated soils with no injection reagents. Phenol and 2,4-dichlorophenol (2,4-DCP), and kaolin and a natural sandy loam soil were selected as model organics and soils, respectively. The results showed that non-uniform electrokinetics can accelerate the desorption and movement of phenol and 2,4-DCP in unsaturated soils. Electromigration and electroosmotic flow were the main driving forces, and their role in the mobilization of phenol and 2,4-DCP varied with soil pH. The movement of 2,4-DCP in the sandy loam towards the anode (about 1.0 cmd(-1)V(-1)) was 1.0-1.5 cmd(-1)V(-1) slower than that in the kaolin soil, but about 0.5 cmd(-1)V(-1) greater than that of phenol in the sandy loam. When the sandy loam was adjusted to pH 9.3, the movement of phenol and 2,4-DCP towards the anode was about twice and five times faster than that at pH 7.7, respectively. The results also demonstrated that the movement of phenol and 2,4-DCP in soils can be easily controlled by regulating the operational mode of electric field. It is believed that non-uniform electrokinetics has the potential for practical application to in situ remediation of organics-contaminated sites.
Luo
Qishi
Q
Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, PR China. lqs01@mails.tsinghus.edu.cn
Zhang
Xihui
X
Wang
Hui
H
Qian
Yi
Y
D000327:Adsorption; D002733:Chlorophenols / Q000737:chemistry*; D004563:Electrochemistry / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D007616:Kaolin; D007700:Kinetics; D019800:Phenol / Q000737:chemistry*; D012987:Soil; D012989:Soil Pollutants; D018505:Waste Management / Q000379:methods
D002733:Chlorophenols; D012987:Soil; D012989:Soil Pollutants; D007616:Kaolin; D019800:Phenol; C004762:2,4-dichlorophenol