Preparation and adsorption properties of chelating resins containing 3-aminopyridine and hydrophilic spacer arm for Hg(II)

Two novel chelating resins, denoted as PS-DEG-3-AP and PS-TEG-3-AP, were obtained by inserting spacer ethylene oxide and ethylene sulfide, respectively, with 3-aminopyridine (3-AP) into polystyrene-co-divinylbenzene. Fourier transform-infrared spectra (FTIR) and elemental analysis were employed to characterize their structures. The adsorption properties of the resins for Hg(II), Ag(I), Fe(III), Pb(II), Co(II), Cu(II), Ni(II), Cd(II) and Zn(II) had been studied, and the results revealed that the resins had higher adsorption capacities and adsorption selectivity for Hg(II). The adsorption kinetics and adsorption isotherms of the resins for Hg(II) were also investigated. The adsorption data of Hg(II) on the resins were fitted well by the pseudo second-order kinetics. Langmuir and Freundlich models were used to describe Hg(II) adsorption isotherms on both resins. The adsorption mechanisms of PS-DEG-3-AP and PS-TEG-3-AP for Hg(II) were confirmed by X-ray photoelectron spectroscopy (XPS). Furthermore, five consecutive sorption–desorption cycles demonstrated that the resins were suitable for repeated use without considerable change in adsorption capacity.