Poly (styrene sulfonamides) with EDTA-like chelating groups for removal of transition metal ions

Chlorosulfonated styrene-divinyl benzene (10%) resin beads (420-590 μm), when treated with an excess of triethylene tetramine (TETA), give a corresponding polymeric sulfonamide with three amine functions. The free amine functions of the resin were carboxymethylated almost quantitatively by reacting with 20% excess of potassium chloroacetate in aqueous solution. The resulting resin with iminoacetic acid functions showed rapid chelating abilities for transition metal ions such as Zn (II), Cd (II), Cu (II), Ni (II), Co (II), and Fe (III) ions. At the neutral pHs the chelating resin was able to reduce the metal ion concentrations lower than 1 ppm in about 15 min of the contacting time. Interestingly, when the resin was used in sodium form, metal binding capacities were higher than the theoretical capacity (1.66 mmol · g^-1), due to simultaneous precipitation of the transition metal hydroxides on bead particles. The resin samples loaded with metal ions can be regenerated more than 10 times by simple acid-base treatments, without activity loss.