Abstract
The equilibrium for the propionic acid extraction by N1923 in three diluents, represented as proton-donator (n-octanol), polar (butyl acetate), inert (hexane) types, have been studied. The diluents had a significant influence on the equilibrium. The loading ratio,
Z, was employed to investigate the effect of diluents on the extraction efficiency. When
Z
exp was lower than 1, N1923 extraction followed the order: n-octanol
>
butyl acetate
>
hexane. When the loading ratio
Z
exp was higher than 1, the order changed to: butyl acetate
>
hexane
>
n-octanol. Equilibrium complex constants
K
11,
K
21,
K
31 have been estimated. The results showed that
K
11 was much higher than
K
21 and
K
31, demonstrated
K
11 as the dominant factor in the extraction process. Comparing the values of
K
11 of all the three diluents, the following order was observed: n-octanol
>
butyl acetate
>
hexane. The influence of amine concentration on the extraction equilibrium constant in different diluents was also investigated. The extraction equilibrium constant
K
11 decreased with the increase of amine concentration in n-octanol. When hexane and butyl acetate were used as diluent, the extraction equilibrium constant
K
11 increased slightly with the increase of amine concentration.