不同电解质浓度下沥青质分子的脱附机理

Desorption Mechanism of Asphaltene Molecules in Different Electrolyte Concentrations

采用耗散型石英晶体微天平(QCM-D)原位研究了不同浓度Na Cl溶液对沥青质的脱附效率,并基于Voigt粘弹性模型对石英晶体表面的吸附质量变化进行了拟合。结合紫外可见光吸收光谱、原子力显微镜和接触角的测试结果,比较了不同矿化度条件下沥青质的实际脱附效率以及解吸附前后的形貌和润湿性变化。研究结果表明,1 000 mg/L Na Cl溶液的加入,使沥青质实现少量脱附;而随后加入50 mg/L Na Cl溶液,促进了二氧化硅基底表面及吸附层油滴表面的双电层扩张,使其电荷屏蔽作用增强,增大了基底与油滴之间的斥力,最终实现沥青质的大量脱附。

The effect of NaCl solutions of different concentrations on the asphaltene desorption was investigated by dissipative quartz crystal microbalance（QCM-D） in situ. The adsorbed mass on the silica surface was fitted by Voigt viscoelastic model. Combined with the test results of Ultraviolet（UV） spectroscopy, atomic force microscope and contact angle, the effeciency of asphaltene desorption as well as changes of morphology and wettability were analyzed under different salinity conditions. It showed that there was a slight desorption in the presence of NaCl 1000 mg/L aqueous solution; Whereas the amount of asphaltene desorption was increased after introducing NaCl 50 mg/L aqueous solution.The electrostatic repulsion among oil droplet and silica substrate was increased due to the expansion of double electrode layer, causing the desorption of asphaltenes.