Investigation On Dissolution Characteristic Of Metal Salt/organic Solvent/Water Mixture

The conversion technology of osmotic energy to electric energy based on the theory ofreverse electro-dialysis is a new way to generate electricity.In the border region of river and the ocean,the sea and rive water with concentration difference are mixed,and Gibbs free energy is converted to electric energy by the aid of RED technology.The research projects by Netherlands and Italy have been conducted to ensure the rational use of this part of energy.In the present study,the low temperature multi-effect distillation technology is introduced to propose a novel closed method of thermal electric conversion based on the theory of reverse electro-dialysis,which is composed of thermal separation of solution and reverse electro-dialysis cells.The conventional concentration difference power-generation technology mainly use the concentration difference between the sea and rive water to generate electricity.Na Cl aqueous solution with high concentration and good electrical conductivity is often used as the working solution in the concentration difference power-generation system.However,the thermal electric conversion efficiency is not high enough to achieve the expected target in a closed system because of the high vaporization heat of water and the consequent thermal separation power.To resolve the problem,selection of suitable working pairs is of critical importance.Thus the primary problem is to study the key properties of varoious solutes.In the present research,the solubility of Li Cl,KCl,Li Br,KI,NH4 Br,CH3COOK,CH3 COOLi and CH3 COONa in ethanol,isopropyl alcohol and trifluoroethanol is measured,respectively.The results show that the solubility of Li Cl in ethanol,isopropyl alcohol and trifluoroethanol,the solubility of KCl,CH3 COONa in trifluoroethanol and the solubility of CH3 COOLi in ethanol decrease with the increase of temperature.While other conditions present the opposite case.However,considerable large solubility of Li Cl and Li Br in ethanol and the solubility of CH3 COONa in trifluoroethanol are still not enough.To find a solution with high solubility,high conductivity and low latent heat of vaporization,the solubility of Li Cl in water/ethanol mixture and CH3 COOK in water/trifluoroethanol mixture are also measured.The results show that the solubility of Li Cl and CH3 COOK increase with the increase of the proportion of water in the mixed solvent.As a result,CH3COOK/water/trifluoroethanol mixture and Li Cl/water/ethanol mixture can be used as working pair in the thermal electric conversion system.In the present research,the solubility of chlorine salt,lithium salt and acetate in the same main group are analyzed.The results show that the solubility varies greatly with the existence of different ions.The solubility of an identical solute in different solvent is quite different since it is influenced by the property of the solvent.For polar solutes,the solubility is higher for stronger polarity of solvent.Apelblat's equation and Yaws' equation are used to fit the experimental data in present research.The relative deviations for correlation of the solubility in pure organic solvent are less than 4% and 2% using Apelblat's equation and Yaws' equation,respectively.By the comparison between the two equations,it is found that fitting result of Yaws' equation is better than that of Apelblat's equation.The fitting results of solubility of Li Cl and CH3 COOK in mixed solvent of the two equations are both very close to the experiment value,which provides an important basis in selection of work pairs in thermo electric conversion technology.