Study on Reactive Extraction of Butyric Acid Using Suitable Extractant and Diluent

Abstract

Reactive extraction is a separation process using the reactions between extractants and the materials extracted. The extractant in the organic phase reacts with the material in the aqueous phase and the reaction complexes formed are then solubilized in the organic phase. In this reactive extraction, extractants like organophosphorous compounds like tri-n-butyl phosphate (TBP), tri-n- octyl phosphine oxide (TOPO) and aliphatic amines (tri-n-octyl amine (TOA), Aliquat 336, Alamine 336 etc.) have been widely used for the extraction of carboxylic acids. Alcohol, ester and ketones are mainly used as diluents for these extractants as they are viscous in nature. Natural diluents like sunflower oil, castor oil, soybean oil are also used as diluents for the reactive extraction. The application of reactive extraction for the separation of carboxylic acids like butyric acid from its aqueous solution is a relatively new technique. Butyric acid is a five carbon chain carboxylic acid. This acid is generally used in food, pharmaceutical and polymer industries as a raw material. In the present work, attempts were made for the recovery of recovery of butyric acid using Tri -Octyl –Amine (TOA) using decanol as diluent. Effect of temperature is studied in the range of (298-318K) to check the feasibility of the system within given temperature range. Results are discussed in terms of distribution coefficient, loading ratio, equilibrium constant, enthalpy, entropy and free energy. It is observed that as temperature increases, distribution coefficient values decreases. The enthalpy and entropy obtained are negative values states that the reactive extraction of butyric acid is an exothermic reaction.