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.

This study indicates that easily and rapidly synthesized HA by microwave-assisted precipitation method could be used as an efficient adsorbent for removal of lead(II) from aqueous solutions.

In this investigation, the reactive extraction of oxalic acid from its dilute solutions using trioctylphosphine oxide (TOPO) or dioctylamine (DOA) mixed with several solvents was studied to examine the most proper extractant mixture. The organic-phase combinations were prepared by merging either TOPO or DOA with n-octane, 1-butanol, 1-decanol, methyl isobutyl ketone (MIBK), diisobutyl ketone (DIBK), and diethyl sebacate (DES), respectively. The distribution coefficient, loading factor, and the extraction yield data were calculated for the interpretation of the results. It is found that in comparison with the physical extraction experiments performed with pure solvents oxalic acid extraction from aqueous solutions can be improved significantly by introducing TOPO or DOA to the extractant composition. According to the results, the maximum oxalic acid extraction is obtained with an extraction efficiency of 98.74% and a distribution coefficient of 78.125 if 1.652 mol•kg −1 of DOA dissolved in MIBK is used as the extractant mixture. It can be inferred that using DOA instead of TOPO gives better results for the oxalic acid extraction; however, an aggregate formation was observed with this extractant leading to the problems in the back extraction step of oxalic acid.

The purpose of this investigation is to compare the extraction efficiency of lactic acid from dilute solutions using several extractant mixtures in order to determine the most efficient solution for the extraction processes. A phosphorus-based extractant, TOPO, has been chosen for the extraction experiments since it has low water solubility and is more environmentally friendly than the amine-type extractants. Also, amine-based extractant DOA is chosen due to the lack of study in the literature on lactic acid extraction using a DOA/solvent system. Organic phases were prepared by mixing TOPO or DOA with eight different solvents (n-octane, isobutyl methyl ketone, 1-octanol, ethyl methyl ketone, diisobutyl ketone, n-decane, diethly sabecate, and 1-decanol), and all experiments were performed at 298.15 K. The results were interpreted using the distribution coefficient (K D ), loading factor (Z), and extraction yield (E %) data. It has been observed that a considerable amount of lactic acid extraction can be achieved by using DOA in the organic phase compared to that attained by using TOPO. It is found that the maximum amount of extracted lactic acid (K D = 56.331) was achieved with 1.654 mol•kg −1 DOA dissolved in 1-octanol with an extraction efficiency of 98.26%, and thus especially the use of a DOA/1-octanol system is recommended for the lactic acid extraction processes.

The aim of this study is to investigate the extraction of citric acid and maleic acid from their aqueous solutions using different solvent–extractant mixtures in order to find the most effective composition for the extraction. Citric and maleic acids are chosen as the carboxylic acids due to their commercial worth in the industrial processes. Carboxylic acids are recovered from their aqueous solutions by reactive extraction, a promising liquid–liquid extraction technique, using trioctylphosphineoxide (TOPO), and a secondary amine called dioctylamine (DOA). TOPO has been chosen as an extractant since it has low water solubility, high stability, and it is more environmentally friendly than the amine-type extractants. For other amine extractants used in reactive extraction processes, there is a lack of study in the literature about the extraction of these acids with DOA. Extractants were dissolved in nine different solvents (butanol, decanol, octanol, isoamylalcohol, octane, decane, methylisobutylketone, and diisobutylketone) having different chemical structures. All experiments were carried out at 298.15 K. Comparisons of the results were made using the distribution coefficient (D), loading factor (Z), and the extraction yield (%E). It has been observed that a considerable amount of citric acid and maleic acid extraction was achieved using DOA (in the range of 13.95–99.19% and 31.94–99.41% according to the diluent used for citric acid and maleic acid, respectively) compared to that achieved with TOPO (in the range of 0.81–67.12% and 16.25–89.33% according to the diluent used for citric acid and maleic acid, respectively).