摘要
采用等温溶解平衡法研究了四元体系Na^+,K^+//Br-,SO_2-4-H_2O在373 K条件下的相平衡关系,测定了平衡溶液的溶解度和密度,并根据实验数据绘制相应的相图、水图和密度图。研究发现:交互四元体系Na^+,K^+//Br^-,SO_2-4-H_2O在373 K温度下,有复盐钾芒硝Na_2SO_4·3K_2SO_4生成,相图由3个共饱和点、7条单变量曲线和5个结晶区组成。其中,5个结晶区分别对应单盐:K_2SO_4,KBr,Na Br,Na_2SO_4和复盐Na_2SO_4·3K_2SO_4(Gla)。
According to the composition of the brine resources in the west of Sichuan Basin, phase equilibria in the quaternary system Na^＋,K^＋//Br^-,SO4^2--H2 O at 373 K is measured by the isothermal solution saturation method, and the solubilities and densities of the solution are determined experimentally. Using the experimental results, the dry salt phase diagram, water diagram and the densities versus composition diagram are obtained. In the phase diagram of quaternary system Na^＋,K^＋//Br^-,SO4^2--H2 O at 373 K, the double salt Na2SO4·3K2SO4 is found. There are three invariant points, seven uninvariant curves and five crystallization fields in the quaternary system. The five crystallization fields correspond to NaB r, Na2SO4, K2SO4, KBr and Na2SO4·3K2SO4（Gla）, respectively. The crystallization field of NaB r has the smallest crystallization area, whereas the double salt Na2SO4·3K2SO4（Gla） has the biggest crystallization field in the quaternary system. It means that the double salt Na2SO4·3K2SO4（Gla） has the smaller solubility, and it can be easiest separated from solution. Compared with the two phase diagrams of quaternary system Na^＋,K^＋//Br～-,SO4^2--H2 O at 323 K and 373 K, the result shows that the numbers of invariant points, crystallization fields and unvariant curves are the same. The double salt all forms in the phase diagrams of quaternary systems at two different temperatures. But univariant curve GH of the corresponding balance solid phase is different and the crystal water of sodium bromide has disappeared at 373 K. In comparison with the quaternary system Na^＋,K^＋//Cl-,SO4^2--H2 O and the quaternary system Na^＋,K^＋//Br^-,SO4^2--H2 O at 373 K, the two phase diagrams have very similar shapes, each of them having three invariant points, seven univariant curves and five crystallization fields. The crystallization field of the salt NaB r is apparently smaller than that of Na Cl. It is also found that halide has the salting-out effect on sulfates. The water content and the density transformation rules are discussed simply. The water content is lower with the higher solution of bromine and the density is higher with the higher solution of bromine.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2016年第4期1123-1128,共6页
CIESC Journal
基金
国家自然科学基金项目(41373062)
高等学校博士学科点专项科研基金项目(20125122110015)
四川省高校科研创新团队项目(15TD0009)~~
关键词
地下卤水
相平衡
溶解性
溶液
钾盐
溴盐
underground brine
phase equilibria
solubility
solution
potassium salt
bromine salt
作者简介
崔瑞芝（1988-），女，博士研究生。
联系人：桑世华。
