Synthesis of functionalized porous silicas via templating method as heavy metal ion adsorbents: the introduction of surface hydrophilicity onto the surface of adsorbents

Bi-functional porous silicas, functionalized via the introduction of chelating ligands (mercaptopropyl and amino-propyl groups), were synthesized for use in the removal of heavy metal ions from aqueous solutions. Dodecylamine was used as a template, and tetraethoxysilane (TEOS) as a silica precursor. Adsorbents were synthesized via a co-condensation process using the sequential or simultaneous addition of TEOS and high concentrations of the organosilanes (3-aminopropyltriethoxysilane and 3-mereaptopropyltrimethoxysilane). The sequential addition of TEOS and organosilanes resulted in well-ordered porous silicates. The effect of the presence of functional groups on the properties of adsorbents was also examined. The results show that amino ligands increased the surface hydrophilicity of the adsorbents. In addition, the adsorbents had high loading capacities and selectivity for mercury ions in aqueous solutions. (C) 2001 Elsevier Science B.V. All rights reserved.