镁硼酸盐水溶液体系热力学与热动力学性质量热法研究

Salt lake brines with high concentrations of magnesium and boron in Qaidam Basin is a treasury of inorganic salts resources. The investigation of the thermodynamics and thermokinetics of the aqueous solution on magnesium borates by a novel adiabatic calorimeter is essential research to obtain the basic thermodynamic datum for the predictive chemical model of complex borate-containing brine system to drive the comprehensive utilization of salt lake resources. In this proposal project, a novel means and method will be used to study the heat of dilutions and heat capacities of the aqueous solution on magnesium borates by using the adiabatic calorimetric analysis to improve the traditional method of solid-liquid coexisted phase equilibrium to avoid the problem of phase transition of magnesium borates in order to demonstrate the thermodynamics and thermo-kinetics of the aqueous solution on magnesium borates. Considering the ion-interaction of borate species and the complex reactions of polymerization and reconciliation existed in solution, the modified Pitzer ion-interaction model of the relative apparent molar enthalpy will be used to fit the Pitzer ion-interaction parameters of different single salt of magnesium borates at different temperatures and their multi-temperature correlation equations as while as the enthalpy, entropy, and Gibbs energy to fill up the thermodynamical datum, which is not reported in the literature. It is significance either to understanding the knowledge of the cause of the mineral formation of the salt-deposits of magnesium borates, ion interaction, phase transition rule and the evolutionary processes in the different borate formation mechanism or to develop the borate-salt chemistry, and explore the processing technology of magnesium borates.

柴达木盆地盐湖是我国无机盐资源的宝库，开展镁硼酸盐低温热力学与热动力学研究，可为构建复杂卤水体系预测化学模型、推动盐湖资源开发利用提供重要的热力学基础数据。本课题采用先进的低温绝热量热技术，改进传统固液相平衡热力学性质研究方法，测定镁硼酸盐体系的多温稀释热和热容，揭示镁硼酸盐溶液稀释过程的热力学和热动力学特征；考虑水溶液中硼物种的聚合和解聚及离子相互作用，发展Pitzer电解质溶液模型，获取不同镁硼酸盐单盐参数及其多温关联式和焓、熵、吉布斯自由能，填补国内外关于镁硼酸盐低温和多温热力学参数的空白，对于深入认识镁硼酸盐卤水成因、离子相互作用及其成盐与相转化规律，发展镁硼酸盐化学、诠释盐湖演化过程中不同时期镁硼酸盐形成机制、探究盐湖镁硼酸盐的加工利用都具有重要意义。

针对我国柴达木盆地盐湖老卤资源，开展了镁硼酸盐固体及水溶液体系低温热力学与热动力学研究，对于推动老卤资源开发利用提供了重要的热力学基础数据。本课题创新镁硼酸盐体系热力学和热动力学性质研究方法，采用先进的低温绝热量热技术、等压技术，改进传统的固液相平衡热力学性质研究方法，揭示了四种镁硼酸盐固体系变温热容、不同镁硼酸盐水溶液体系多温多体系相转化、等压平衡浓度、水活度、热容、混合热热力学性质和体积性质，揭示镁硼酸盐水溶液离子相互作用，发展Pitzer电解质溶液离子相互作用的相对表观摩尔焓、表观摩尔体积模型，获取不同镁硼酸盐单盐参数及其多温关联式，填补国内外关于镁硼酸盐低温和多温热力学参数的空白。已发表论文27篇，其中SCI论文23篇、EI期刊论文1篇、中文核心论文3篇，参加国际会议3次、全国会议4次，交流会议论文15篇，培养硕士研究生5名，获天津市专利优秀奖1项、国际热力学会第24届国际大会Poster奖1项。超额完成了本项目任务。