Adsorption of Ni2+ from aqueous solutions by novel polyethyleneimine-attached poly(p-chloromethylstyrene) beads

Abstract

In this study Ni2+ adsorption properties of polyethyleneimine (PEI)-attached poly(p-chloromethylstyrene) (PCMS) beads were investigated. Spherical beads with an average size of 186 gm were obtained by the suspension polymerization of p-chloromethylstyrene conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, PCMS beads had a specific surface area of 14.1 m(2)/g. PEI chains could be covalently attached onto the PCMS beads with equilibrium binding capacities up to 208 mg PEI/g beads, via a direct chemical reaction between the amine and chloro-methyl groups. After PEI adsorption with 10% (w/w) initial PEI concentration, free amino content of PEI-attached PCMS beads was determined as 0.91 mEq/g. PEI-attached PCMS beads were utilized as adsorbents in the adsorption/desorption of Ni2+ ions from synthetic solutions. The adsorption process was fast; 90% of adsorption occurred within 90 min, and equilibrium was reached at around 2 h. Adsorption capacity was obtained to be 78.2 mg/g at a pH of about 6.0. The chelating beads can be easily regenerated by 0.1 M HNO3, with higher effectiveness