Sustainable preparation of spherical amphoteric organics:Isoelectric point-spherical agglomeration technology

This work developed a sustainable and highly-efficient isoelectric point-spherical agglomeration (IPSA) technology for preparing spherical particles of amphoteric organics. The IPSA technology couples isoelectric point crystallization and spherical agglomeration (SA), eliminating the most polluting part in SA technology, i.e. the use of solvents and anti-solvents, and also achieving multiple recycling of mother liquor for the first time. It thereby reducing the amount of organic solvents by approximately 60% compared with SA technology. The mechanism of the IPSA technology was studied by in-situ process analysis tools, which included phase separation, crystallization, wetting, primary adhesion, secondary adhesion and consolidation. Then, the mother liquor recycling experiments of IPSA process were designed based on three model substances of L-tryptophan, L-leucine and L-methionine respectively, which verified the sustainability of IPSA technology. In addition, the effects of the BSR (bridging liquid/solute volume ratio), agitation rate and alkali dropping rate were investigated to determine the optimal parameters. • This work designs an isoelectric point-spherical agglomeration (IPSA) technology. • The IPSA mechanism was proposed and the process parameters were investigated. • Compared to SA, IPSA reduced the amount of organic solvent by approximately 60%. • IPSA realized the recycling of mother liquor for the first time. • Spherical particles of three amino acids were successfully prepared by the IPSA.