Recovery of aconitic and lactic acids from simulated aqueous effluents of the sugar-cane industry through liquid-liquid extraction

The recovery of aconitic and lactic acids from dilute aqueous effluents of the sugar-cane industry by a solvent extraction technique has been investig ated in order to reduce environmental pollution and in view of the possible uses of pure solutes in the field of foods and pharmaceuticals. Reactive e xtraction of carboxylic acids with tributylphosphate dissolved in dodecane was examined. Experiments were performed at 25 degreesC for three extractan t concentrations of 50%, 60% and 70% (mass%) in dodecane. The decrease of s pecific gravity and viscosity of solvent resulting from the presence of an inert diluent was favourable to the phase settling and the mass transfer. T he percentage of acids recovered in the organic phase for a volumetric solv ent ratio varying from 0.5 to 5.0 was determined. Taking into account the d ifference between the partition coefficients for the carboxylic acids under consideration, the selectivity of solvent with regard to aconitic acid als o was quantified. Moreover, owing to its water-insolubility, its availabili ty and its low cost, tributylphosphate can be considered as a promising ext ractant for large-scale applications. (C) 2000 Society of Chemical Industry .