Extraction chemistry of fermentation product carboxylic acids

Abstract

Within the framework of a program aiming to improve the existing extractive recovery technology of fermentation products, the state of the art is critically reviewed. The acids under consideration are propionic, lactic, pyruvic, succinic, fumaric, maleic, malic, itaconic, tartaric, citric, and isocitric, all obtained by the aerobic fermentation of glucose via the glycolytic pathway and glyoxylate bypass. With no exception, it is the undissociated monomeric acid that is extracted into carbon-bonded and phosphorus-bonded oxygen donor extractants. In the organic phase, the acids are usually dimerized. The extractive transfer process obeys the Nernst law, and the measured partition coefficients range from about 0.003 for aliphatic hydrocarbons to about 2 to 3 for aliphatic alcohols and ketones to about 10 or more for organophosphates. Equally high distribution ratios are measured when long-chain tertiary amines are employed as extractants, forming bulky salts preferentially soluble in the organic phase.

Stoichiometric and Spectroscopic Study of Reactive Extraction of Phenylacetic Acid with Tri-n-Butyl Phosphate

“…Stoichiometry of complex formation of phenylacetic acid and tri-n-butyl phosphate Using mass action law 40 , the extraction equilibrium for phenylacetic acid can be written as a reaction of one molecule of phenylacetic acid and γ molecule of tri-n-butyl phosphate participating in the formation of the complex. The mechanism of reactive extraction of phenylacetic acid in terms of apparent equilibrium constant, E can be written as:…”

“…The distillation method is a well-established technology, but its drawbacks involve formation of high-boiling internal esters, dimers, and greater power consumption. [20][21][22][23][24][25] Reactive extraction with the proper selection of diluents and extractants can provide high selectivity and extraction but suffers from toxicity problems of solvents toward microbial strains. Selection of an extractant and diluent for reactive extraction should be on the basis of minimal toxicity and maximum capacity.…”

Alternative Feedstocks Program Technical and Economic Assessment: Thermal/Chemical and Bioprocessing Components

“…In particular, several amine-based extractants show remarkable selectivity for acetic acid over water with distribution coefficients of greater than 10 as the acetic acid concentration goes below 0.5 wt % (Wardell and King, 1978). In addition, data have been gathered for the distribution properties of many fermentation product carboxylic acids, including acetic, lactic, and citric acids (Kertes and King, 1986). One could also envision placing these same types of functional groups on solid adsorbents to carry out separations and recovery.…”

Reactive Extraction of Citric Acid Using Different Extractants: Equilibrium, Kinetics and Modeling

“…Secondly, there are phosphorus-bonded oxygen donor extractants, such as tri-n-butyl phosphate (TBP), trioctyl phosphine oxide (TOPO), etc., and third category com-prises of high molecular weight aliphatic amine extractants, such as tri-n-octyl amine (TOA), Aliquat 336 (A336), etc. [5][6][7][8][9] As these extractants are costly as well as viscous, they are often employed after dilution in some conventional solvent (diluent). The diluent provides the desired solvation media to the extractant by tuning its desired physicochemical properties.…”