石油污染多孔介质湿润性变异特征

Characteristics of Wettability Variation of Oil-Contaminated Porous Medium

一定程度的石油污染可使多孔介质的湿润性发生变异，导致介质持水能力降低、地下水石油污染、粮食产量品质下降等．采用滴水穿透时间法与酒精溶液入渗法，测定了亚粘土和粗砂在不同柴油、机油含量下的斥水水平，确定了亚粘土、粗砂由亲水表面变为疏水表面的临界含油量．结果表明，亚粘土、粗砂湿润性变异的临界机油含量分别约为7％、0．5％，粗砂湿润性变异的临界柴油含量约为14％，而柴油污染对亚粘土湿润性的影响不显著．另外，当石油污染多孔介质的含水量达到某一临界值时，湿润性将再次发生反转，由疏水表面变回亲水表面．测得机油、柴油污染粗砂的临界含水量约在0．2％～1％之间，机油污染亚粘土的临界含水量在数值上与其含油量近似相等．

A certain degree of oil pollution can lead to wettability variation in porous medium, which can bring about low water- holding capacity, oil contamination of groundwater, low food quality and production. In this study, water repellency of sand and clay was measured by WDPT and MED methods under different diesel and engine oil contents. Critical oil content of porous media in oil-contaminated porous media was determined preliminarily, beyond which hydrophilic surface could change into hydrophobic surface. The results show that critical oil contents of clay and sand contaminated by engine oil are about 7% and 0. 5% respectively. Critical oil content of sand contaminated by diesel is about 14%, while diesel doesn＇t have remarkable effect on water repellency. In addition, when water content increases to a critical value, wettability of oil-contaminated porous medium will reverse again. Critical water contents of sand contaminated by engine oil and diesel are both between 0. 2 % - 1%, while critical water content of clay contaminated by engine oil is approximately equal to its oil content in value.