Non-dispersive liquid extraction of Cr(VI) by TBP/Aliquat 336 using chitosan-made hollow fiber

TBP and alkylammonium extractants were investigated for chromate removal from dilute solutions using chitosan-made hollow fibers. Chromate is adsorbed by the chitosan fiber and simultaneously desorbed by the extractant. The influence of chromate concentration, extractant concentration, extractant volume on relative concentration decrease were investigated as a function of time. These experimental parameters barely influenced the decrease in the relative concentration. Fiber length is more significant in the control of the extraction kinetics. In recirculation flow mode, the relative concentration can be well described as an exponential function of time. The kinetic constant varies as a linear function of fiber length. Amine extractants (Aliquat 336, Alamine 336, Amberlite LA-2) are better extractants than TBP both from the kinetics and equilibrium standpoints. With Aliquat 336 the final Cr(VI) concentration tends to zero, while with TBP, the equilibrium is controlled by the volume of the extractant.