物理化学学报 >> 1994, Vol. 10 >> Issue (06): 536-542.doi: 10.3866/PKU.WHXB19940611

研究论文 上一篇    下一篇

三元体系Li+, K+(Mg2+)/SO2-4-H2O 25 ℃相关系和溶液性质的研究

李冰, 王庆忠, 李军, 房春晖, 宋彭生   

  1. 中国科学院青海盐湖研究所,西宁 810008
  • 收稿日期:1993-03-19 修回日期:1993-07-12 发布日期:1994-06-15
  • 通讯作者: 宋彭生

A Study on the Ternary Systems Li+, K+(Mg2+)/SO2-4-H2O at 25 ℃

Li Bing, Wang Qing-Zhong, Li Jun, Fang Chun-Hui, Song Peng-Sheng   

  1. Institute of Salt Lakes, Academia Sinica, Xining 810008
  • Received:1993-03-19 Revised:1993-07-12 Published:1994-06-15
  • Contact: Song Peng-Sheng

摘要:

研究了两个三元体系Li~+,K~+/SO_4~(-2)-H_2O(1)和Li~+,Mg~(2+)/SO_4~(2-)-H_2O(2)在25 ℃时的相关系和溶液密度、粘度、折光率、电导、pH等物化性质.体系(1)25 ℃等温图由三条溶解度线构成,分别对应于K_2SO_4、复盐LiKSO_4和Li_2SO_4·H_2O相区.复盐LiKSO_4 25 ℃时为不相称溶解化合物,其转变温度为45.5~46 ℃,高于此温度时变为相称溶解.复盐与LiSO_4无固溶体形成.体系(2)为简单共饱型,两段溶解度线对应于体系的两种原始组分Li_2SO_4·H_2O和MgSO_4·7H_2O的结晶区,无复盐或固溶体形成,亦未发生脱水作用.用Pitzer模型检验测得的两个体系25 ℃的溶解度,并用经验或半经验公式描述物化性质随浓度的变化规律,其结果令人满意.

关键词: 水盐体系, 溶解度, 相平衡, 锂化合物

Abstract:

Solubilities of the ternary systems Li~+, K~+/SO_4~(2-)-H_2O (1) and Li~+, Mg~(2+)/SO_4~(2-)-H_2O (2) were investigated by isothermal method at 25 ℃. Physico-chemical properties of solutions, such as density, refractive index, viscosity, conductivity, and pH, were determined. Phase diagram of the system (1) consists of three sollubility branches and three crystallization fields corresponding to K_2SO_4, LiKSO_4, and Li_2SO_4·H_2O. LiKSO_4 is an incongruent compound, and its transition poin is 45.5~46.0 based on our graphical estimate. No solid solution of LiKSO_4 with Li_2SO_4·H_2O was found in the system. System (2) is of a simple eutonic type. Pitzer model of electrolyte solution was used to check the obtained solubilities. Data comparison gives good agreement. Physico-chemical properties of solutions, such as density, refractive index, viscosity, conductivity, pH, and X-ray diffraction, IR spectra, DTA of LiKSO_4 were measured. Two equations were used to correlate density, refractive index with copmposition. Differences between measured and calculated values are less than 0.6% for density, 0.15% for the later.

Key words: Salt-water system, Solubility, Phase equilibrium, Li compound