Intensification of enzymatic conversion of glucose to lactic acid by reactive extraction

Abstract

Lactic acid is an important commercial product and extracting this out of aqueous solution is a growing requirement in fermentation-based industries and recovery from waste streams. The design of an amine extraction process requires (i) equilibrium and (ii) kinetic data for the acid-amine (solvent) system used. Equilibria and kinetics for lactic acid extraction by Alamine 336 in octanol as a diluent have been determined and compared with other diluents studied earlier. An approach for extracting the lactic acid by a long-chain tertiary amine, which is in the dispersed phase as a liquid ion exchanger (LIX), is presented. A mathematical model for slurry phase reactor with glucose in the continuous aqueous phase, the amine with a diluent in the dispersed phase and the immobilized enzyme as the solid catalyst, has been developed using equilibrium and kinetic data for reactive extraction. E ects of various parameters a ecting the conversion of glucose have been discussed. The model has been solved for batch and semi-batch modes. It has been shown that the semi-batch mode yields approximately ÿve times higher productivity than batch mode. ?

Intensification of conversion of glucose to lactic acid: equilibria and kinetics for back extraction of lactic acid using trimethylamine

“…The complexation of lactic acid with Alamine 336 in octanol at 30 • C is described as follows (Wasewar et al, 2003):…”

Intensification of conversion of glucose to lactic acid: equilibria and kinetics for back extraction of lactic acid using trimethylamine

“…• C is described as follows (Wasewar et al, 2003): The equilibria in the aqueous phase are described as follows (Poole and King, 1991): …”

“…In an actual industrial unit as shown in the owsheet (Wasewar et al, 2003) the thermal regeneration o gases containing water vapour and TMA can be ÿrst cooled in a falling ÿlm type of condenser where most of the TMA will be absorbed by the condensing water vapour. It is well known that when the direction of heat and mass transfer is the same (such as in this case) relatively high mass transfer coe cient are realized (Bennett and Myers, 1962).…”

“…It was found that octanol is better solvent than the other two solvents on equilibrium and kinetics consideration. Wasewar et al (2003) have suggested a more e cient method for lactic acid recovery. Lactic acid extracted in the organic phase can be back extracted with a stronger volatile amine like trimethylamine (TMA) in aqueous phase.…”

“…The organic phase, Alamine 336 in octanol was chosen because of favourable equilibria, substantial equilibrium data, and interpretation thereof for forward extraction of lactic acid (Wasewar et al, 2003). The regeneration data of TMA have been presented.…”