Sorption of phenanthrene by kaolin and efficacy of hydraulic versus electroosmotic flow to stimulate desorption
Sorption of phenanthrene by kaolin and efficacy of hydraulic versus electroosmotic flow to stimulate desorption
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DOI：
10.1016/j.jece.2015.08.011
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发表时间：
2015-12
影响因子：
7.7
通讯作者：
Ikrema Hassan;E. Mohamedelhassan;E. Yanful;Z. Yuan
中科院分区：
文献类型：
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作者：
Ikrema Hassan;E. Mohamedelhassan;E. Yanful;Z. Yuan
石油碳氢化合物是疏水性的，在释放到环境中时往往会附着在土壤上。对于大多数修复技术来说，从土壤中解吸污染物是必要的。在地下和原位修复中，主要的解吸机制是反向扩散，本研究通过三个试验建立了菲作为污染物和高岭石作为土壤基质的吸附和解吸动力学。在14℃、22℃和30℃的温度下，用浓度为300~800g/L的六种菲溶液进行吸附等温线测试，测定了三种温度下的Freundlich方程常数KF值分别为0.147、0.133和0.109μGln/g(1+n)。使用无菲溶液进行解吸试验，以确定室温(∼22℃)下的解吸参数。此外，还进行了两个系列的试验，以比较在室温下水力和电渗流对菲的解吸效果。采用固定壁式水力渗透仪，在260kPa压力下产生1.4m×10−3m L/S的水力流量，同时施加低水平的直流电流密度(0.3-0.43mA/cm~2)产生相当于水力流量的电渗流量。电渗流解吸后出水样品中菲的浓度是水力解吸后的3~4倍。此外，液压流量测试所需的功率比电动流量测试的消耗功率高出三个数量级。结果表明，电渗流解吸菲比水力解吸更有效。
Petroleum hydrocarbons are hydrophobic and tend to adhere to soil when released into the environment. Desorption of the contaminant from soil is necessary for most remediation technologies. In subsurface and for in-situ remediation, the dominant desorption mechanism is back diffusion.In this study, three tests were conducted to establish sorption and desorption kinetics for phenanthrene as a contaminant and kaolinite as a soil matrix. Sorption isotherm tests were conducted at temperatures of 14, 22, and 30 °C using six phenanthrene solution containing concentrations from 300 to 800 μg/L. Freundlich equation constant,Kf,values of 0.147, 0.133, and 0.109 μgLn/g(1+n)were determined for the three temperatures. Desorption tests were conducted using phenanthrene-free solution to determine desorption parameters at room temperature (∼22 °C). In addition, two test series were performed to compare phenanthrene desorption by hydraulic and electroosmotic flows at room temperature. A fixed wall hydraulic permeability apparatus was used to generate a hydraulic flow rate of 1.4 × 10−3mL/s at a pressure of 260 kPa, while a low level direct current density (0.3–0.43 mA/cm2) was applied to generate electroosmotic flow rate equivalent to the hydraulic flow. The phenanthrene concentration in effluent samples after desorption by electroosmotic flow was found to be three to four times the concentration after desorption by hydraulic flow. Moreover, the power required in the hydraulic flow test was three orders of magnitude higher than the consumed power in the electrokinetic flow test. These results show that phenanthrene desorption by electroosmotic flow is more efficient than by hydraulic flow.