Synthesis and characterization of phosphonate ester/phosphonic acid grafted styrene - Divinylbenzene copolymer microbeads and their utility in adsorption of divalent metal ions in aqueous solutions

In this paper the preparation and characterization of some chelating resins, phosphonate grafted on polystyrene-divinylbenzene supports, are reported. The resins were prepared by an Arbuzov-type reaction between chloromethyl polystyrene - divinylbenzene. copolymers and triethylphosphite, yielding the phosphonate ester copolymer (resin A). This can be hydrolyzed by HC1 to yield the phosphonate/phosphonic acid copolymer (resin B). The phosphonate resins A and B were characterized by determination of the phosphorus content, infrared spectrometry, and thermal analysis. The total sorption capacity of the phosphonate ester functionalized resin (A) and phosphonate/phosphonic acid functionalized resin (B) for divalent metal ions such as Ca2+, Cu2+, and Ni2+ was studied in aqueous solutions. Resin A retains similar to 3.25 mg of Ca2+/g of copolymer and 2.75 mg Of Cu2+/g of copolymer, but retains no Ni2+ at pH 1. On the other hand, resin B retains 8.46 mg of Ca2+/g of copolymer, 7.17 mg Of Cu2+/g of copolymer, and no Ni2+ at pH 1. Efficient Ni2+ retention was observed at pH 7 only for the phosphonatelphosphonic acid functionalized resin (B) at the level of 19 mg of Ni2+/g of polymer B. Polymer A was incapable of retaining Ni2+ at pH 7.