Non-covalent self-assembly of multi-target polystyrene composite adsorbent with highly efficient Cu(II) ion removal capability

Functionalized nanocomposite adsorbents based on multiple sites of sorption are critically important for advancing removal of heavy metal ions. Herein, a non-covalently assembly strategy for fabrication of efficient adsorbent with multiple-site adsorption capability is introduced. A novel hybrid nanomaterial was fabricated by encapsulating chitosan molecules (CS) into charged polystyrene resin (PS) through electrostatic adsorption. The resulting hybrid absorbent (PS-CS) demonstrates highly efficient sorption toward cupric ion, mainly because of the electrostatic interactions of sulfonate group and chelation of -NH2 and -OH groups of chitosan with cupric ion. Meanwhile, the obtained composites with interior well-dispersed chitosan molecules give specific selectivity for cupric ion in the present of divalent competition ions such as Ca2+ and Mg2+. Adsorption equilibrium data can be described with Freundlich isotherms model and the pseudo-second-order model. The kinetic rate constants have been determined for PS and PS-CS nanocomposite. In this paper, it is suggested that charged groups in host materials not only enhance the fixation and dispersion performance of embedded molecules but provide more target sites for nanocomposite, thus enhancing capacity for sorption of metal ions. Therefore, construction of multi-target nanocomposites provides conceivably promoted development of highly efficient adsorbents for toxic metals abatement.