阻抗法监测离子液体膜的吸附性能

Monitor the adsorption of an ionic liquid film by impedance sensor

采用高频阻抗计测定了离子液体与有机溶剂相互作用过程中的电阻抗变化,选用1-甲基-3-正辛基咪唑氟硼酸盐([C8Mim][BF4])作为模型离子液体,所用有机溶剂包括乙醇、丙酮、乙酸乙酯、四氯化碳。结果表明,在[C8Mim][BF4]中加入丙酮或乙醇后,混合物的电导率和介电常数显著增加,而加入四氯化碳所引起的阻抗变化较小。根据离子液体膜的阻抗变化可以监测膜的吸附特性,该文采用阻抗法和对电导率和介电常数有频率响应的串联式压电传感器实时检测了[C8Mim][BF4]膜吸附有机溶剂蒸气的过程,为研究离子液体的吸附性能提供了一种新的测量方法。

The electric impedance of an ionic liquid during the interaction with an organic solvent was investigated by an impedance analysis method. 1-methyl-3-octylimidazolium fluoroborate C8MimBF4 was used as the model ionic liquid. And acetone, ethanol, ethyl acetate and tetrachloromethane were used as the model organic solvents. The experimental results revealed that the conductivity and dielectric constant of the mixture of C8MimBF4 and acetone or ethanol were increased with increasing concentration of the organic solvents. But the addition of tetrachloromethane in C8MimBF4 caused only a slight change in its impedance. According to the changes in impedance, the adsorption processes of the ionic liquid film to organic solvent were monitored. The adsorption of C8MimBF4 to acetone and ethyl acetate were flowed by an impedance analyzer and a series piezoelectric sensor, respectively. The impedance method offers a simple way to measure the adsorption behavior of an ionic liquid film.