Reactive Extraction of Formic Acid with Alamine-336 and Various Solvents

Low cost separation methods are required for carboxylic acid recovery. In the present study, formic acid was recovered from its aqueous solutions by reactive extraction. 1-octanol, hexane and xylene were selected as diluents, while Alamine 336, a long chain tertiary amine mixture, was used as extractant. Inert diluents (xylene and hexane) were modified using relatively polar solvent to increase the percent recovery. Effects of solvent type, concentration of extractant and modifier ratio on reactive extraction of formic acid were investigated. Distribution coefficient (D) and loading ratio (z) values were calculated using the equilibrium data. Highest D values were obtained with 1-octanol among the diluents studied. Modification of inert diluents resulted in higher extraction efficiency. The trend continued with the organic phases including Alamine 336. Distribution coefficient values increased with the increase in modifier percent and amine concentration in the organic phase. Loading ratio values were especially observed to be affected from solvent type.