Process Design Framework for Inorganic Salt Recovery Using Antisolvent Crystallization (ASC)

Antisolvent crystallization (ASC) can be an alternative separation strategy over evaporative or cooling crystallization for selective salt recovery from aqueous salt mixtures. While a large amount of literature has been focused on phase equilibrium data generation, the implication of phase behavior on antisolvent selection and process performance has not been adequately discussed. This work aims to develop a methodical framework combining solubility behavior, phase balance, antisolvent selection, and solvent recovery to design sustainable ASC processes for the selective isolation of salts from aqueous solutions. The methodology was tested for the application of ASC to separate sodium sulfate from sodium chloride, as those mixtures generate as saline effluent from salt-harvesting activities. Technoeconomic feasibility, sustainability, and life cycle analysis of the proposed ASC process were performed to establish its potential toward commercialization. Several environmental impact categories were analyzed on the ASC process with antisolvent recovery, direct disposal, and incineration, comparing their performance and highlighting the overall sustainability. The presented process design framework will guide early feasibility studies considering ASC for inorganic salt separation and purification from saline effluents.