Microchannel based Multistage Solvent Extraction Studies for the Separation of Propionic Acid from its Aqueous Mixture using Hydrocarbon Solvents

Abstract

Solvent extraction is an important industrial operation where several stages are needed for a desired separation. Microchannel based solvent extraction is widely reported for process intensification. However, all these works are confined to a single-stage extraction till date. For industrial application knowledge of multistage extraction is mandatory. This work focuses on the multistage microchannel extraction using a model mixture containing aqueous propionic acid. Four different single solvents were employed in this study hexane, toluene, heptane, and cyclohexanol. The Effect of flow rate, flow ratio on percentage extraction, extraction efficiency, and the required number of stages was investigated. The number of stages required for the maximum recovery of PA from the raffinate is 5 for hexane &heptane and 3 for toluene and 2 for cyclohexanol. The percentage extraction of solvents obtained overall through all the stages is, cyclohexanol, 57–89%, toluene, 35–50%, heptane, 27–51%, and hexane 19-31.3%. Cyclohexanol produced the maximum percentage extraction. The extraction efficiency and the volumetric mass transfer coefficient decreased with the stage numbers. The maximum extraction efficiency for all the solvents is in the range of 98-99.8%. A microchannel stack is found to reduce the total annual cost (TAC). Particularly, fabrication in India results in very less capital cost for the microchannels i.e.1.9–14.3% of TAC. The total annual cost analysis of toluene is the minimum than other solvents.