Polyacrylic acid gel is known for its ion chelating properties. Its poor mechanical resistance hinders its use in extraction operations. Crosslinking can improve the mechanical resistance but lowers the chelating capacity. A gel encapsulation technique has been developed to obtain a material constituted by a low cross linked polyacrylic gel coated by a polyamide membrane and having improved mechanical resistance with respect to the corresponding gel. Extracting properties of various metal ions (Cu, Ni, Co and Zn) carried out in "batch" and "column" processes are presented. Mass transfer modeling studies have been carried out by using the mass action law for the ion exchange equilibrium and by describing the ion flow with the Nernst-Planck equation. Collocation in finite elements was used to solve the model equations. Results indicate that the capsules can be compared with ion exchange resins.