Theoretical and experimental study of palladium(II) extraction from hydrochloric acid solutions into Aliquat 336/PVC membranes

The extraction of palladium(II) from its hydrochloric acid solutions into poly(vinyl chloride) (PVC)-based membranes containing Aliquat 336 chloride as both the extractant and the plasticizer was experimentally studied. The results showed that these membranes extracted palladium(II) rapidly and to a very high degree. This property can be used either for the analytical determination of trace levels of palladium(II) or for the recovery of this precious metal from industrial wastewaters and hydrometallurgical solutions. A mathematical model for the palladium(II) extraction into an Aliquat 336/PVC membrane which takes into account the interfacial palladium(II)–Aliquat 336 chloride reaction and the diffusion mass transport through the membrane was developed. The model was fitted to the experimental extraction data to determine the values of the relevant physicochemical constants (i.e. diffusion coefficients and kinetic rate constants).