Interaction of divalent cations Zn, Cd and Hg on surface of silica gelwith aminoethanethiol as evaluated by calorimetric titration

Calorimetric titration was applied to study the interaction of zinc, cadmium and mercury on surface of silica gel modified with 2-aminoethanethiol, using 3-chloropropyltrimetoxysilane as precursor silylating agent. The anchored Sil–SNH2 surface gave 0.70 mmol g–1 of molecules covalently bonded per gram of silica. This surface displayed a chelating moiety containing sulfur and nitrogen basic centers, which are potentially capable of extracting cations from aqueous solutions, such as MCl2 (M=Zn, Cd, Hg). This process of extraction was carried out by the batch method when similar chemisorption isotherms were observed for all cations.