化工学报2023，Vol.74Issue(10)：4051-4062,12.DOI:10.11949/0438-1157.20230506
三元体系KCl-K2B4O7-H2O在318.15 K下热力学活度系数及相平衡实验和预测
Measurements and predictions of thermodynamic activity coefficients and phase equilibria in ternary system KCl-K2B4O7-H2O at 318.15 K
摘要
Abstract
The potassium-boron rich underground brines in Sichuan Basin are important liquid mineral resources.To reveal the enrichment law of boron and potassium in the underground brines and the exploitation of brine resources,the studies on thermodynamic properties and phase equilibria of the underground brines are essential foundation.The ternary system KCl-K2B4O7-H2O containing boron and potassium is the most important subsystem in this brine.In this work,ion selective electrode is used to measure the cell potential of the cell without liquid junction K-ISE | KCl(m1),K2B4O7(m2)| Cl-ISE.The total ionic strength of the mixed solution is 0.01-1.00 mol·kg-1,and the ionic strength ratio of K2B4O7 yb is 0.8,0.6,0.4,0.2 and 0,respectively.The mean activity coefficients of KCl in mixed solutions KCl-K2B4O7-H2O were calculated by using the measured cell potentials and Nernst equation at 318.15 K.Then,multiple linear regression and nonlinear programming were used to determine the single salt parameters β(0),β(1)and CΦ of K2B4O7,and the mixed ion interaction parameters θCl,B4O5(OH)4 and ψK,Cl,B4O5(OH)4 in Pitzer model.The fitted parameters of Pitzer model can be used to further calculate the mean activity coefficient of K2B4O7,osmotic coefficient,water activity,and excess Gibbs free energy of the mixed solutions.Furthermore,the phase equilibria of ternary system KCl-K2B4O7-H2O at 318.15 K are determined experimentally in this work.The results show that the phase diagram of the system contains one invariant point,two solid crystallization regions(KCl and K2B4O7·4H2O),and two isothermal solubility curves.Using the ion interaction parameters and Pitzer model fitted in this work,the phase equilibrium of the ternary system was theoretically predicted.The predicted results show that the calculated values are in good agreement with the experimental data.The research results provide an important theoretical basis for the development and utilization of boron-potassium resources in the underground brines.关键词
活度系数/Pitzer模型/电动势法/相平衡/四硼酸钾Key words
activity coefficient/Pitzer model/cell potential method/phase equilibrium/potassium tetraborate分类
化学化工引用本文复制引用
桑世华,刘佳,杨晓军,冯振华,谭啸天,岑雨秋,唐彬彬..三元体系KCl-K2B4O7-H2O在318.15 K下热力学活度系数及相平衡实验和预测[J].化工学报,2023,74(10):4051-4062,12.基金项目
四川省自然科学基金重点项目((2022NSFSC0022) （(2022NSFSC0022）
四川省地质调查院科研基金项目(SDDY-Z2022013,SCIGS-CZDZX-2023001) （SDDY-Z2022013,SCIGS-CZDZX-2023001）
