Properties of a bifunctional chelating resin containing aminomethylphosphonate and sulfonate derived from poly(ω-bromobutylstyrene-co-divinylbenzene) beads

A bifunctional chelating resin containing aminomethylphosphonate and sulfonate groups (RC4NPS) was derived from macroreticular poly(ω-bromobutylstyrene-co-divinylbenzene) beads (RC4B). First, the bromine atoms in RC4B were replaced with phthalimide groups and then sulfonate groups were introduced into the benzene rings on the polymer chains. After the phthalimide groups were hydrolyzed with an ethanol solution of hydrazine hydrate, the resulting primary amino groups at the end of the butyl groups were converted into aminomethylphosphonate groups by the Mannich condensation reaction. For comparison, a monofunctional aminomethylphosphonate resin (RC4NP) was also prepared by eliminating the sulfonation step. The nitrogen, phosphorus and sulfur contents of RC4NPS were found to be 2.07, 2.98 and 2.19 mmol/g, respectively. The nitrogen and phosphorus contents of RC4NP were 2.50 and 3.39 mmol/g, respectively. The acid capacities of RC4NPS and RC4NP were 6.97 and 6.23 meq/g, respectively. The metal ion selectivity of both resins was evaluated by measuring the pH dependence of the distribution ratios (D) of Fe(III), Lu(III), Gd(III), La(III), Pb(II), Ca(II), Mg(II), Cu(II), Zn(II) and Ni(II). This selectivity study indicates that the metal ion selectivity of RC4NPS can be expressed as a convolution of the metal ion selectivity of RC4NP with that of a sulfonate resin.