Kainite crystallization from RO bittern: A novel approach using discontinuous evaporation

Abstract

Addressing global water scarcity and achieving sustainable water management necessitates innovative solutions for handling reverse osmosis (RO) brine. This by-product, rich in high-value salts, poses environmental challenges due to its high salinity and chemical load. This study explores a novel approach for recovering valuable minerals from brine, focusing on Kainite, a mineral with substantial industrial applications and notorious for its nucleation difficulties. This research introduces a temperature-altering technique for Kainite crystallization, adjusting temperatures from 69 °C, 55 °C, 35 °C, and 25 °C, each subsequently reduced to 15 °C. Advanced characterization techniques were utilized to analyze the crystallized phases. The FREZCHEM model was used for a comparative analysis between isothermal evaporation and the experimental discontinuous evaporation results. Findings indicate that effective Kainite crystallization occurs only with discontinuous evaporation at specific temperature pairs: 55 °C to 15 °C and 69 °C to 15 °C. A novel application of Jänecke phase diagrams through the projection of crystallization path between 55 and 15 °C, and 69 and 15 °C, was instrumental in accurately predicting the crystallization sequence under these conditions. This study underscores discontinuous evaporation's potential for resource recovery from RO brine, contributing to sustainable water management.