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-aminopropyltrimethoxysi lane resulted in a new silylating agent, which was anchored onto a silica s urface via the sol-gel procedure. The synthesised silica gel surface has be en used to adsorb divalent cations from aqueous solutions at room temperatu re. The series of isotherms of adsorption were adjusted to a modified Langm uir 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 th e 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.