Adsorption and separation of cations on chemically modified silica gel synthesised via the sol-gel process

The reaction of ethylene sulfide [(H2C)(2)S] with 3-aminopropyltrimethoxysilane resulted in a new silylating agent, which was anchored onto a silica surface via the sol-gel procedure. The synthesised silica gel surface has been used to adsorb divalent cations from aqueous solutions at room temperature. The series of isotherms of adsorption were adjusted to a modified Langmuir equation from data obtained by suspending the solid in water with MCl2 (M=Cu, Ni, Co, Pb and Hg) solutions, which gave the maximum number of moles adsorbed as 1.66, 1.44, 1.26, 1.90 and 8.51 mmol g(-1), respectively. The immobilised surface was also used for the separation of these five cations in a column. Column resolution, R-(s), was determined for all cations as the ability of the surface to separate metal ions, determined as R(s)Co-Ni=0.20, R(s)Co-Cu=0.73, R(s)Co-Pb=2.50, R(s)Co-Hg=1.73, R(s)Ni-Cu=0.55, R(s)Ni-Pb=2.25, R(s)Ni-Hg=1.69, R(s)Cu-Pb=1.33, R(s)Cu-Hg=1.52 and R(s)Pb-Hg=1.35.142206220