Cr(III) removal by macroreticular chelating ion exchange resins

The poly(styrene-co-divinylbenzene) beads were synthesized by suspension polymerization using benzoylperoxide as an initiator and i-octane as a diluent. The copolymer beads with a particle size range of 32-60 mesh were selected. Chloromethylation was performed with chloromethylether at 0degreesC using tetrachloroethane as swelling agent and AlCl3 as catalyst. The phosphorylation of copolymer beads (RS) and its chloromethylated derivative (RCS) was carried out using a mixture of PCl3 and AlCl3 under the reflux. The phosphorylated resins (RSP) were further oxidized using concentrated HNO3 to obtain the oxidized form of RSP resins (RSPO). The removal of Cr(III) by the resins RSP, RSPO, and RCSP containing phosphinic, phosphonic, and methylenephosphonic groups, respectively, was investigated by batch and column methods. The results were compared with that of Diaion CRP-200 resin having methylenephosphonic functional groups. These resins exhibited a high affinity for Cr(III). The percent removal of Cr(III) reached a plateau with almost a 100% of removal at pH range between 2 and 2.5. The breakthrough capacity decreased in the order RCSP>RSPO>Diaion CRP-200>RSP.