A Quantitative Multi-Criteria Solvent Selection Method for Extraction Processes: Case Study—Downstream Purification of Sucrose-Based Surfactants

Abstract

This work developed a novel method for the identification and selection of green solvents for extraction processes. The methodology was experimentally validated in the downstream separation of sucrose-based surfactants obtained from a solvent-free transesterification of sucrose and methyl palmitate (MP). First, a preliminary solvent screening was carried out taking into account environmental consciousness, extraction effectiveness, and predicted operating costs, combining both theoretical and empirical inputs. Potential solvents were first selected from a green solvents list used at the pharmaceutical industry, and the affinity with reactants was assessed based on the Hansen solubility parameters. Solvent suitability was ranked according to a novel objective function that incorporated the heat of vaporization, normal boiling point, cost, and availability. In the case of study, ethyl acetate was identified as the most promising solvent for MP extraction. This and other solvents were experimentally evaluated to validate the selection method and to assess their extraction performance. According to different effectiveness criteria, ethyl acetate was confirmed as the preferable extraction solvent. Finally, MP extraction from reaction media was optimized, varying temperature, number of stages, and solvent loading. Purified sucrose esters were subjected to bleaching obtaining a product under market specifications.