Equilibrium studies of aconitic acid extraction using tri-n-octyl amine (TOA) as extractant

Conventionally, aconitic acid (AA) is extracted from natural resources like molasses (sugar cane), red beet etc. However, to met the ever increasing demand of AA for use in biopolymer, surfactants and in drugs, an alternative way is needed which is economical as well as eco-friendly. Fermentation is an alternative route for the production of AA to meet industrial demand. But, it is very challenging to separate AA from fermenter. Out of different techniques available to separate carboxylic acids from fermentation broth; reactive extraction is found highly suitable. Nevertheless, for higher selectivity and effective acid recovery using extraction, investigation on efficiency of extraction systems (diluents and extractants) is highly desired. In this work, equilibrium studies of reactive extraction of trans-aconitic acid (TAA) from aqueous solutions with different diluents (cyclohexanone, MIBK, benzene, and n-heptane) with tri-n-octyl amine (TOA) as an extractant was performed. Using the above extraction systems with different initial acid concentrations and vol% of extractants, distribution coefficients (KD) were evaluated. Also, effect of initial acid concentration and effect of diluents on extraction efficiency (E) of TAA was studied. Extraction efficiency of (benzene + TOA) diluent system is found highest. Besides that extraction efficiency was found independent on phase volume ratio when TOA was used as extractant.