Investigation of liquid–liquid phase equilibria for reactive extraction of lactic acid with organophosphorus solvents

Abstract

BACKGROUND: Lactic acid is a versatile commodity chemical with a variety of applications. Synthesis of lactic acid either through fermentation of carbohydrates or through chemical synthesis is state of the art. Separation from dilute aqueous solution is complex and accounts for the major part of production costs. Reactive extraction based on reversible adduct formation is a promising alternative for the separation of lactic acid. RESULTS:Extraction was carried out with the organophosphorus solvents tri-n-butyl phosphate, tri-n-octylphosphine oxide and Cyanex 923. Shellsol T was used as diluent. Partition coefficients increase with increasing extractant content and decreasing temperature. Cyanex 923 has several advantages compared with tri-n-butyl phosphate and tri-n-octylphosphine oxide with respect to lactic acid distribution and hydrodynamic properties. Liquid-liquid phase equilibria for lactic acid extraction with Cyanex 923 were modeled. Selectivity of lactic acid extraction with respect to glycolic acid and formic acid was discussed. CONCLUSION: The organophosphorus extractant Cyanex 923 was found to be an appropriate solvent for lactic acid extraction from aqueous solutions. Experimental data and model data based on the Law of Mass Action showed good agreement. Lactic acid extraction from multi-acid solution showed good selectivity compared with glycolic acid. Lactic acid selectivity is low with respect to formic acid.

Reactive Extraction of Lactic Acid, Formic Acid and Acetic Acid from Aqueous Solutions with Tri-n-octylamine/1-Octanol/n-Undecane

“…LUX et al [37] reported the degree of dissociation decreases with increasing acid concentration. Therefore, at low acid concentration, this term cannot be neglected.…”

Salting-out assisted solvent extraction of L (+) lactic acid obtained after fermentation of sugarcane bagasse hydrolysate

“…Datta et al [15], in their recent review, have confirmed that unlike alkylamines, TBP forms a coordinate bond with the carboxylic acid, including lactic acid. Since the bond strength of the coordinate bond is higher than ionic interactions and TBP is a strong Lewis base [23], they collectively contributed towards its high extraction ability in the absence of diluent. It was apparent that TBP should give better results than alkylamines and our results…”

Potential and assessment of lactic acid production and isolation - a review

“…Isoamyl alcohol led to the highest extraction efficiency at about 80%. Lux et al . found that Cyanex 923 diluted in ShellsolT is, with regard to distribution coefficient and hydrodynamics, a proper extractant for lactic acid extraction from aqueous solution.…”