Experimental and Theoretical Investigations on the Reactive Extraction of Itaconic (2-Methylidenebutanedioic) Acid Using Trioctylamine (N,N-Dioctyloctan-1-amine)

The paper presents the equilibrium distribution study of itaconic acid (also known as 2-methylidenebutanedioic acid, 0.615 mol.kg(-1)) between water and trioctylamine (TOA, 0.374 mol.kg(-1) to 1.946 mol.kg(-1)) at 298 +/- 0.1 K. The extract phase is prepared by varying the concentration of TOA and dissolving the same in four categories of solvents (alkane, ester, ketone and alcohol). The batch equilibrium results are presented in the form of loading ratio (Z), extraction efficiency (% E), and distribution coefficient (K-D). Maximum extraction efficiency of 94.80% with the value of K-D equal to 18.20 is obtained at 1.946 mol.kg(-1) of TOA in octan-1-ol. The extractability of TOA with different solvents is found to be in the order of alcohol > ketone > ester > alkane. The values of stoichiometric coefficient (1:m), overall equilibrium constant (K-E) and individual equilibrium constants (K-11, K-21, and K-12) are estimated using equilibrium data and employing mass action law. The acid molecules form 1:1 and 2:1 type of complexes (m < 1) with TOA dissolved in alkanes, and 1:1 and 1:2 solvates (m > 1) with TOA dissolved in alcohols, ketones, and esters. The estimated values of K-E followed the same trend as the distribution coefficient (alcohol > ketone > ester > alkane).