Selectivity of cyclam modified poly(p-chloromethyl styrene-ethyleneglycol dimethacrylate) microbeads for Cu(II), Ni(II), Co(II) and Zn(II)

Poly(p-chloromethyl styrene-ethyleneglycol dimethacrylate) polymeric microbeads, poly(p-CMS-EGDMA), with an average size of 186 μm were synthesized by the suspension polymerization of p-chloromethyl styrene conducted in an aqueous medium. 1,4,8,11-Tetraazacyclotetradecane (cyclam) was reacted with polymer active group under the nitrogen atmosphere for 18 h at 65 °C. Fourier transform infrared spectrometer (FT-IR) and elemental analyzer were used to characterize the plain and cyclam modified microbeads. The affinity of the cyclam modified poly(p-CMS-EGDMA) microbeads for some metal ions was examined. The adsorption/desorption behaviour of the modified microbeads from aqueous solution containing different amount of metal ions (0.05-20 mM) at different pH values (2.0-7.0) was studied. The uptake of metal ions onto the modified poly(p-CMS-EGDMA) microbeads from solution containing a single metal ions were found to be 232.1, 119.2, 132.1, and 116.8 mg g^-1 polymer for Cu(II), Zn(II), Ni(II), and Co(II), respectively. More than 95% of the adsorbed metal ions were desorbed for 48 h in desorption medium containing 3 M HNO₃. Poly(p-CMS-EGDMA) co-polymeric microbeads containing cyclam ligand were found to be suitable for repeated use without noticeable loss of adsorption capacity. The selectivity of metal ions was found in the order of Cu(II) ≫ Ni(II) > Zn(II) > Co(II). The recovery of different metal ions in the competitive medium is really high for Cu(II), Co(II), Ni(II), and Zn(II) besides the other metal ions namely Cr(III), Pb(II), Cd(II), and Mn(II) at pH 5.0 and also pH 2.0.