Facile preparation of a silica-sphere–poly(catechol hexamethylenediamine) composite for the competitive removal of cadmium(II), lead(II), and copper(II) ions

A silica-sphere–poly(catechol hexamethylenediamine) (PCHA–SiO 2 ) composite was prepared via the one-step facile polymerization of catechol and hexamethylenediamine; this method uses a silica sphere as a hard template. The chemical structures and morphologies of this composite were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and transmission electron microscopy. The adsorption experiments indicated that the PCHA–SiO 2 composite served as a very attractive adsorbent for Pb(II)-, Cu(II)-, and Cd(II)-ion removal at lower concentrations and had very good selective adsorption abilities for Pb(II) and Cu(II) ions in a solution contaminated with these three ions at higher concentrations. These interesting results may have been due to the reversible H + adsorption–desorption properties of the characteristic phenol amine structure of the PCHA–SiO 2 composite. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135 , 45839.