Cryogenic-crosslink synthesis of Ba(OH)2@gelatin microcapsules for the removal of sulfate in lithium refinery

Abstract

Sulfate (SO42−) is a major impurity in the production of battery-grade LiOH from acid leaching of ores using H2SO4. The conventional process to remove SO42− by precipitation with Ba2+, however, is difficult to control stoichiometrically in industry, and overdosed Ba2+ frequently causes secondary contaminations. Moreover, fine particles of BaSO4 precipitate require extra steps to remove, which significantly increases the cost of separation. To overcome these limitations, we developed a novel adsorbent, the Ba(OH)2@gelatin microcapsule, by embedding Ba(OH)2 inside the matrix of gelatin through a special cryogenic-crosslink method using liquid nitrogen to snap-freeze the gelatin-Ba(OH)2-water d..