Adsorption of cadmium (II), zinc (II) and iron (III) from water by new cross-linked reusable polystyrene adsorbents

Abstract

In the present study, the commercial polystyrene (PS, M = 350 000) was grafted with organophosphate groups via amino linkages. PS with amino groups was initially prepared by nitration and reduction reactions. Then, the aminated PS was firstly cross-linked with 2,2′-dichlorodiethylether (DCDEE), to generate a polymer named PS-NH-DCDEE, and then with tris-(2-chloroethyl) phosphate (TCEP) to get a polymer named PS-NH-TCEP. The obtained products were characterized by several methods, including FT-IR spectroscopy, thermodynamic analysis (DTA), thermogravimetric analysis (TGA), elemental analysis (EA), and X-ray diffraction (XRD) and scanning electron microscopy (SEM). The evaluation of metal cations extraction was performed by flame atomic absorption spectroscopy (FAAS) on the remaining solutions. The new cross-linked polymers were tested for their ability to extract Zn(II), Cd(II) and Fe(III) from aqueous phase at room temperature. FT-IR measurements have clearly demonstrated the interaction between metal and ligands in the matrix polymers. The new materials PS-NH-DCDEE and PS-NH-TCEP exhibited high selectivity towards Fe3+ and Zn2+ with levels of extraction yields between 90 and 98%. Although after five consecutive adsorption–desorption cycles, no obvious change in the adsorption capacity of the polymers was found, which suggests that the obtained materials were suitable for the effective removal of heavy metal ions from aqueous solutions.