Lactic acid is an important commercial product and extracting it 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 for lactic acid extraction by alamine 336 in methyl-iso-butyl-ketone (MIBK) as a diluent have been determined. The extent to which the organic phase (amine +MIBK) may be loaded with lactic acid is expressed as a loading ratio, z=[HL](o)/[B](i,o). Calculations based on the stoichiometry of the reactive extraction and the equilibria involved indicated that more lactic acid is transferred to the organic phase than would be expected from the (1:1) stoichiometry of the reaction. The extraction equilibrium was interpreted as a result of consecutive formation of two acid-amine species with stoichiometries of 1:1 and 2:1. Equilibrium complexation constant for (1:1) and (2:1) has been estimated. Kinetics of extraction of lactic acid by alamine 336 in MIBK has also been determined. In a first study of its kind, the theory of extraction accompanied by a chemical reaction has been used to obtain the kinetics of extraction of lactic acid by alamine 336 in MIBK. The reaction between lactic acid and alamine 336 in MIBK in a stirred cell falls in Regime 3, extraction accompanied by a fast chemical reaction occurring in the diffusion film. The reaction has been found to be zero order in alamine 336 and first order in lactic acid with a rate constant of 1.38 s(-1). These data will be useful in the design of extraction processes.

Lactic acid is an important commercial product and extracting this from aqueous solution is a growing requirement in fermentation-based industries. The design of an amine extraction process requires (i) equilibrium and (ii) kinetic data for the acid±amine (solvent) system used. The equilibrium complexation constants for ratios of (1:1) and (2:1) have been estimated. The kinetics of extraction of lactic acid by Alamine 336 in decanol has also been determined. The reaction between lactic acid and Alamine 336 in decanol in a stirred cell falls in Regime 3, ie extraction accompanied by a fast chemical reaction occurring in the diffusion ®lm. The reaction has been found to be zero order in Alamine 336 and ®rst order in lactic acid with a rate constant of 0.21 s À1. These data will be useful in the design of extraction processes.

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. ?

The sulphidation of calcined limestone with H2S , COS and mixtures of H2S and COS was studied in a thermogravimetric analyzer at temperatures between 500 and 700°C. The applied H2S-and COS-pressures corresponded with those in coal gas produced by modern coal gasifiers, i.e. 50-12,000 Pa for H2S and 50-1000 Pa for COS. The reaction orders in H2S and COS as well as the activation energies of the involved reactions were determined. The mechanism of sulphidation was examined by simulating measured conversion vs time behaviour with the grain size distribution model of Heesink et al. (1993, Chem. Enong J. 53, 25-37).

Alamine 336 is an e ective extractant for the recovery of lactic acid from aqueous solutions. An approach for regeneration and product recovery from such extracts is to back extract lactic acid with a water soluble, volatile tertiary amine such as trimethyl amine. Equilibrium data are presented that show near stoichiometric recovery of lactic acid from amine extract. Kinetics of back extraction of lactic acid from Alamine 336 in octanol into aqueous trimethyl amine (TMA) has been presented. Back extraction reaction in a stirred cell falls in Regime 3, extraction accompanied by a fast chemical reaction. The reaction has been found to be zero order in TMA and ÿrst order in lactic acid with a rate constant equal to 16:67=s 1 . The data reported in this work will be useful in designing the lactic acid recovery system. In thermal regeneration of TMA, 99% of TMA was removed at 200 mmHg from trimethylammonium lactate aqueous solution. ?