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

Abstract

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 HCl 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 ∼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 phosphonate/phosphonic 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.