Extraction of Propionic Acid from Aqueous Solutions Using Tri-n-octylphosphine Oxide and Dioctylamine in Different Solvents

摘要

This work examines the reactive extraction of propionic acid, a promising liquid-liquid extraction technique, using tri-n-octylphosphine oxide (TOPO) or dioctylamine (DOA) diluted with eight different solvents (n-octane, methyl isobutyl ketone (MIBK), 1-octanol, ethyl methyl ketone, diisobutyl ketone, n-decane, diethyl sabecate, 1-decanol) at 298.15 K to determine the most efficient mixture for the extraction processes. A phosphorous-based extractant, TOPO, has been chosen for the extraction tests since it has low water solvency and is more ecologically agreeable than the amine-type extractants. Among the other amine extractants reported in reactive extraction studies, there is no study on propionic acid extraction using DOA in the literature. Physical extraction experiments with pure solvents were also performed to analyze the effect of TOPO and DOA on the extraction process. Distribution coefficients, loading factors, and extraction yields of the processes were determined for the explanation of the results. It was concluded that the addition of TOPO or DOA to the organic phase significantly improves the extraction of propionic acid from its aqueous media. The extraction of propionic acid, using the binary solutions of TOPO/diluent or DOA/diluent, improves with an increase in the initial TOPO or DOA concentration. The highest extraction yield, E % = 98.01, was achieved with the DOA + methyl isobutyl ketone (MIBK) extractant system (1.652 mol kg(-1)), with a distribution coefficient of K-D = 49.352; thus, the use of the DOA/methyl isobutyl ketone system in the organic phase is suggested for the propionic acid extraction methods.