Effects of process factors on performances of liquid membrane-based transfer of indole-3-acetic acid

The paper has aimed at studying the transfer of indole 3-acetic acid (IAA) from a feed aqueous solution to a stripping aqueous solution of NaOH using a chloroform bulk liquid membrane and trioctylamine (TOA) as a ligand (L). Initial molar concentrations of IAA in the feed phase, c_IAA,F0 (10^-4-10^-3 kmol/m³), of TOA in the membrane phase, c_L,M0 (10^-2 and 10^-1 kmol/m³), and of NaOH in the stripping phase, c_NaOH,S0 (10^-2 and 1 kmol/m³), were selected as process factors. Their effects on the final values of IAA concentration in the feed phase (c_IAA,Ff) and stripping solution (c_IAA,Sf), extraction efficiency (E_F), distribution coefficient (K_D), and recovery efficiency (E_R) were quantified using multiple regression equations. Regression coefficients were determined from experimental data, i.e., c_IAA,Ff,ex = 0.02-1 × 10^-4 kmol/m³, c_IAA,Sf,ex = 0.22-2.58 × 10^-3 kmol/m³, E_F,ex = 90.0-97.9%, K_D,ex = 9.0-46.6, and E_R,ex = 66.5-94.2%. It was found that c_IAA,F0 had the most significant positive effect on c_IAA,Ff and c_IAA,Sf, whereas c_NaOH,S0 had a major positive effect on E_F, K_D, and E_R. A deterministic model based on mass transfer of IAA was developed and its parameters, i.e., mass transfer coefficient of IAA-L complex in the liquid membrane (0.82-11.5 × 10^-7 m/s) and extraction constant (1033.9-1779.7 m³/kmol), were regressed from experimental data. The effect of c_L,M0 on both parameters was significant.