A Novel Amino and Carboxyl Functionalized Mesoporous Silica as an Efficient Adsorbent for Nickel(II)

In this study, the as-prepared spherical mesoporous silica was modified by amino and cyano groups via grafting, and the amino and carboxyl functionalized adsorption materials (MSS@NH2@COOH) were obtained after cyano group hydrolysis. The introduction of amino and carboxyl groups increases the surface active sites of the materials. The materials were characterized by SEM, TEM, XRD, N2 adsorption/desorption, XPS, etc. BET analysis revealed the amino and carboxyl functionalized mesoporous silica maintained their mesostructure nature and its specific surface area was 113 m2·g–1. TG-DTA and FT-IR confirmed effective grafting on the surface of mesoporous silica with functionalized groups. The simulated wastewater of Ni(II) was carried out to test the adsorption properties of the materials, and several influential factors (pH, initial nickel ion concentration, adsorbent dose) were discussed. The saturated adsorption capacity increased clearly from 46.55 mg·g–1 of MSS to 125.57 mg·g–1 of MSS@NH2@COOH. Even recycling three times, the removal rate of Ni(II) ions using MSS@NH2@COOH as an adsorbent could still be over 75%. Adsorption isotherms, kinetics, and thermodynamics of adsorption were taken to clarify the adsorption process. This newly developed adsorbent material does exhibit good reusable performance and effective removal of the heavy metal ions of Ni(II).