Extraction rate of palladium using divinylbenzene microcapsules containing tri-n-octylamine as the extractant

The extraction of palladium(II) from an aqueous hydrochloric solution was carried out using divinylbenzene microcapsules containing tri-n-octylamine as the extractant. The preparation of these microcapsules was affected by the preparation conditions, such as the concentrations of the divinylbenzene, tri-n-octylamine and diluent. In the case of extremely low or high concentrations of divinylbenzene, and for the high concentration of tri-n-octylamine, the matrix-type microcapsules could not be prepared. The morphologies the prepared of microcapsules were spherical and the surface of the microcapsules was very smooth. The adsorption of palladium(II) onto the microcapsules was negligible compared to the extraction of palladium(II), and it found that the adsorption of palladium(II) onto the microcapsules did not occur. The extraction of palladium(II) into the microcapsules was affected by the characteristics of microcapsules such as, the surface area, pore diameter and volume, and the encapsulation efficiency of the tri-n-octylamine. The extraction of palladium(II) into the microcapsules seemed to have three steps. The first extraction step is caused by the tri-n-octylamine existing near the surface of the microcapsules. The second step is caused by the internal diffusion. The final step is the extraction equilibrium. Based on these results, the microcapsule that has a high encapsulation efficiency of tri-n-octylamine and small pore diameter seems to show the high extraction performance.