(472b) Intensified Liquid-Liquid Extraction with Chemical Reaction By Emulsification
Effluents from biorefinery processes like pulping serve as representative separation task. Such effluents often contain a significant amount of carboxylic acids like acetic acid or formic acid. Through spiking an appropriate solvent with an aliphatic alcohol, the extraction rate of the carboxylic acids can be increased by chemical conversion via esterification which yields a favorable change of the physio-chemical properties of the constituents. Admixture of homogeneous catalysts to the solvent provides an additional benefit by increasing the reaction rate of the esterification step. 4-dodecylbenzenesulfonic acid (4DBSA) is a suitable catalyst. This highly potent catalyst, which additionally acts as a strong anionic surfactant, offers access to two different process routes.
The first route focuses on the prevention of emulsification by adjusting the hydrophilic-lipophilic balance value (HLB value) through adding a second surfactant to the system. Admixture of nonionic surfactants (e.g. SPAN®85) significantly enhances primary phase separation.
The second process route makes use of emulsification in order to increase the interaction between reactants and catalyst, thus increasing the reaction rate although splitting of the emulsion must be applied prior to product isolation. This technology is a promising alternative to state of the art isolation of carboxylic acids from aqueous effluents by liquid-liquid extraction.