Functionalized silica for heavy metal ions adsorption

Heavy metals adsorbents were prepared by co-condensation of tetraethoxysilane and functionalized trialkoxysilane RSi(OR′)3. Functionalized porous silicas with aminopropyl (H2N(CH2)3-), [amino-ethylamino]propyl- (H2N-(CH2)2-NH(CH2)3), (2-aminoethylamino)-ethylamino]propyl (H2N-(CH2)2-NH-(CH2)2-NH(CH2)3-), and mercaptopropyl (HS-(CH2)3-) groups were synthesized using dodecylamine as structure directing agent. These materials have been characterized by elemental analysis, powder X-ray diffraction, nitrogen gas sorption, Fourier transform infrared and Raman spectroscopies and thermogravimetric analysis. These organo-silicas were prepared for use in the removal of heavy metal ions from aqueous solutions. Samples synthesized with [amino-ethylamino]propyl- and (2-aminoethylamino)ethylamino]propyl- functions show a high loading capacity for Cu2+, Ni2+, Co2+ and the anion Cr(VI). The sample synthesized with a mercaptopropyl function has a high loading capacity for Cd2+.