Separation of metal ions by water‐insoluble polymers containing sulfonic/sulfonate groups

A water‐insoluble polymer, poly(sodium 4‐styrene sulfonate), was synthesized by radical polymerization at different amounts (2, 4, 6, and 8 mol %) of crosslinking reagent (CR). At the lowest CR level (2 mol %), only a water‐soluble polymer is obtained, and consequently it could not be studied as resin. The polymerization yield ranged from 82.6 to 91.6%. The resin is characterized by FTIR spectroscopy, thermal analysis, and scanning electron microscopy. The metal ion affinity is studied for the cations: Hg(II), Cd(II), Zn(II), Pb(II), Cr(III), and Al(III) with a batch equilibrium procedure under different experimental conditions. The metal ion affinity increased as the pH increased. At pH 5, the resin showed an affinity greater than 97% for all metal ions. Hg(II) showed the highest retention value at pH 2. The maximum retention capacity is determined at optimum pH for Hg(II), Cd(II), Pb(II), and Zn(II).