Metastable Dissolution Regularity of Nd3+ in Na2CO3 Solution and Mechanism

Abstract

The carbonate solution-dissolved rare earth showed some metastable chemical characteristics. In this paper, the systematic investigation of metastable dissolution regularity of Nd3+ in Na2CO3 solution was carried out. The results showed that Nd3+ has an instantaneous saturated solubility in Na2CO3 solution. When the amount of the dissolution Nd3+ did not reach the instantaneous saturated solubility, the solution was in a stable-state period. Once the concentration of Nd3+ exceeded the instantaneous saturated solubility, the solution was no longer in the metastable state and generated the neodymium double salt of carbonate precipitates rapidly. The molecular dynamics simulation of the solution in the metastable state was carried out. In high concentration Na2CO3 solution, dissolved Nd3+ had a coordination reaction with the CO32–. Also, there was a stronger interaction between Na+ and CO32–, which caused the effective concentration of free CO32– which could react with Nd3+ to become lower. Thus, these reasons make the solution exhibit a metastable state. In that metastable period, the dissolved Nd3+ becomes steady and hard to generate the neodymium double salt of carbonate precipitates.