Comparative Study on Reactive Extraction of Picolinic Acid with Six Different Extractants (Phosphoric and Aminic) in Two Different Diluents (Benzene and Decan-1-ol)

The equilibrium study on reactive extraction of picolinic acid by six different extractants (phosphoric and aminic) dissolved in two different diluents (benzene and decane-1-ol) is carried out to evaluate the performance of extractants and diluents. The extraction ability in terms of the distribution coefficient (K-D) is found to be in the order of tri-n-octylamine (TOA)>= tri-n-dodecylamine (TDDA)>di-2-ehylhexyl phosphoric acid (D2EHPA)>tri-n-butyl phosphate (TBP)>tri-octyl methyl ammonium chloride (Aliquat336)>tri-n-octyl phosphine oxide (TOPO) with both diluents. Decan-1-ol is found to be the better solvating medium for the acid-extractant complexes. A mathematical model based on mass action law is employed to estimate the values of partition coefficient (P) and dimerization constant (D) in physical extraction, and equilibrium extraction constants (K-E) in chemical extraction. The values of loading ratios (Z) less than 0.5 imply the formation of (1:1) acid:-extractant solvates in the organic phase. Decan-1-ol with TOA is the most effective solvation medium with K-D, (max) = 9 at 0.01 kmol.m(-3) of picolinic acid and K-E = 19.448 m(3) . kmol(-1)