石盐溶解过程中氯同位素分馏的初步研究

采用氯同位素组成测定的正热电离质谱法,研究了模拟石盐快速和慢速溶解过程及达到溶解-结晶平衡状态后氯同位素分馏现象。用Na2SO4饱和溶液模拟水溶剂中快速溶解过程,用99.5%乙醇模拟非水溶剂慢速溶解过程。在水溶剂和非水溶剂中,氯离子含量呈相反的变化趋势。快速溶解过程中,氯同位素分馏系数的变化范围为0.999 25～1.001 09,平均值为1.000 29,基本与自然界盐湖卤水石盐结晶体系的趋势相似;慢速溶解过程中氯同位素分馏系数的变化范围为0.999 34～1.001 07,平均值为0.999 51,此过程中开始能反映出NaC l慢速结晶过程的氯同位素分馏,处于溶解与再结晶共存时,氯同位素处于0分馏状态。NaC l的溶解基本能反映出自然界中盐湖卤水快速结晶和慢速结晶中的氯同位素分馏。

Preliminary Study for Chlorine Isotopic Fractionation in the Dissolution of NaCl

The fractionation of chlorine stable isotope in dissolution of NaCl was investigated systemically.The composition of chlorine stable isotope was determined by positive thermo ionization mass spectrometry,and using saturated Na2SO4 and 99.5% ethanol to control the fast and slow dissolution rate.The fractionation factors（α） of chlorine isotope,range from 0.999 to 1.001 in saturated Na2SO4 solutions,and the average was 1.000,which in accordance to the fractionation factor of chlorine isotope in quick-crystallization in the natural salt lake.The fractionation factor（α） of chlorine isotope,ranging from 0.999 to 1.001 in ethanol solution,and the average 1.000 was identical with the fractionation factor of chlorine isotope in slow-crystallization.But when recrystallization and dissolution coexist,no chlorine isotope fractionation was found.The studied dissolution process of NaCl can preliminary manifests the quick-crystallization and slow-crystallization in natural brine from salt lake.