LiX(X=Cl,Br,I)在乙醇、异丙醇及三氟乙醇中的电导率实验研究

Experimental study on conductivity of LiX(X=Cl, Br, I) in ethanol, isopropanol and 2,2,2–trifluoroethanol

为了研发逆电渗析法闭式热电转换系统匹配工作溶液,选取强电解质 LiCl、LiBr 和 LiI 为溶质,低气化潜热的乙醇、异丙醇及三氟乙醇为溶剂,利用所建立的电导率测试装置进行实验研究。通过数据拟合(修正高斯振幅方程法)和溶液热力学、电化学理论分析,获得溶质、溶剂、温度以及添加剂对溶液电导率的影响规律及作用机理。结果表明:当溶质相同时,LiX 乙醇体系电导率最大,LiX 异丙醇体系最小;而当溶剂相同时,LiI 溶剂体系电导率最大,LiCl-溶剂体系最小。实验还发现提升溶液温度或加入强极性添加剂(H2O、二甲基乙酰胺)均可强化溶液电导性,而添加 N-甲基吡咯烷酮和二氯甲烷对体系电导率影响非常微弱。

In order to develop suitable working fluids for a closed type heat-power conversion system with reverse electrodialysis method, three strong electrolytes (LiCl, LiBr and LiI) were selected as the solutes and three solvents with low latent heat of vaporization (ethanol, isopropanol and 2,2,2 trifluoroethanol) were used as solvents to study the conductivities of solutions by using a conductivity measurement apparatus. Effects of solute, solvent, temperature, and additives on solution conductivity were studied by experimental data correlation (modified GuassAmp equation) and solution thermodynamical/electrochemical analysis. The results show that the LiX ethanol and LiX isopropanol systems have the maximal and minimum conductivities, respectively. The LiI solvent system possesses the maximal conductivity and the LiCl solvent system has the minimum conductivity when using the same solvent. Conductivities were also found to be improved by increasing the solution temperature or adding additives with strong polarity (H2O, N,N-dimethylacetamide). However, there is no obvious effect when adding either dichloromethane or N,N,-dimethylpropionamide into the solutions.