Betaine·HCl-6EG-nNiCl2·6H2O低共熔离子液体的黏度和电导率

摘要

The viscosity and electrical conductivity of Betaine·HCl-6EG-nNiCl2·6H2O deep eutectic ionic liquids, formed by adding nickel(Ⅱ) chloride hexahydrate (NiCl2·6H2O) into a deep eutectic solvent (DES) composed of Betaine hydrochloride (Betaine·HCl) and Ethylene glycol (EG) in 1:6 molar ratio, were reported at 303—353 K and 303—348 K with an interval of 5 K under atmospheric pressure. The viscosity and electrical conductivity associated with temperature and NiCl2·6H2Oconcentration were investigated, respectively. The results revealed that within the selected temperature and NiCl2·6H2O concentration ranges, Betaine·HCl-6EG-nNiCl2·6H2O deep eutectic ionic liquids showed low viscosities and good electrical conductivities. With increasing temperature, the viscosities decreased and electrical conductivities increased. The effect of temperature was more significant on viscosity than on electrical conductivity. The dependence of temperature of viscosity and electrical conductivity was found to be greatly described by Arrhenius empirical expressions. According to these expressions, the activation energies for viscous flow and conduction were calculated. With increasing NiCl2·6H2O concentration, the values of the activation energies for viscous flow and conduction increased. Because of the adding NiCl2·6H2O, the formations of the larger size complex ions reduced the concentrations of the effective conductive ions and increased the ionic radius, resulting in increasing viscosity and decreasing electrical conductivity.%在常压下303～353 K和303～348 K温度范围分别测定了低共熔溶剂盐酸甜菜碱-乙二醇(Betaine·HCl-6EG)中加入不同浓度NiCl2·6H2O形成的Betaine·HCl-6EG-nNiCl2·6H2O低共熔离子液体的黏度和电导率，研究了温度、NiCl2·6H2O浓度对其黏度、电导率的影响规律。结果表明，在所研究的温度和NiCl2·6H2O浓度范围内低共熔离子液体 Betaine·HCl-6EG-nNiCl2·6H2O 都具有较低的黏度和良好的导电性。随着温度的升高，黏度减小，电导率增大，温度对黏度的影响更显著；黏度、电导率与温度的关系均可以用Arrhenius经验公式描述，由此计算得到其黏滞活化能和电导活化能。随着 NiCl2·6H2O 浓度的增加，黏滞活化能和电导活化能均会增大；NiCl2·6H2O 的加入使得离子液体形成尺寸较大的络合离子，导电离子的有效浓度降低、离子半径增大，导致其电导率减小、黏度增大。