Abstract:
Carboxylic acids recovery from dilute aqueous solutions is a growing requirement due to the increasing demand for use of pure acids. Reactive extraction is proposed as an alternative to conventional methods of recovery, since the selectivity of separation is remarkably enhanced in reactive extraction.
The aim of this study is to perform the equilibrium studies for the recovery of glycolic and glyoxalic acids from their synthetic aqueous solutions by reactive extraction and investigate the effects of various parameters such as initial acid concentration in the aqueous phase (0.05 — 0.4 M), temperature (20°C — 60°C), organic phase extractant concentration (10% - 30%), type of the extractant (Methyl Tri-Capryl Ammonium Chloride, Tri-Butyl Phosphate) and type of diluent.
The results of the experiments showed that the degrees of extraction increased with decreasing use of diluent with the extractant. The degree of extraction decreased with increasing initial acid concentration of the aqueous phase. the performance of the diluents were investigated by performing reactive extraction with pure diluents and solution of Aliquat 336 (Methyl Tri-capryl Ammonium chloride) and Tri-butyl Phosphate in alcohols, esters and inerts at different concentrations of extractant. It was observed that alcohols had higher salvation power and
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resulted higher degree of extraction. Higher equilibrium coefficient was obtained for aliquat 336 in 1-decanol for both the carboxylic acids.
Among the different extratants highest degree of extraction was with 10% Aliquat 336 in 1-Decanol for both the acids for the extraction of 0.05 N acid solution.
The present work is a first step in the design of industrial reactive extraction process that is going to attempt forward and backward extraction of glycolic and glyoxalic acid simultaneously to achieve continuous product recovery. The equilibrium data can be combined with further studies as the next step of designing a separation module.
Keywords: Reactive extraction, Glycolic acid, Glyoxalic acid, Equilibrium studies, Aliquat 336, TBP, Temperature studies, Kinetics.
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