The Kinetics of Adsorption Binding of Ba2+ Ions by Trimethylsilylated Silica

It was established that incomplete substitution of free silanols of fumed silica surface on (CH3)3Si-groups leads to an increase in the ability of modified SiO2 to adsorb Ba2+ cations from an electrolyte solution. Silica with 48.3% of trimethylsilyl (TMS) groups adsorbs 1.8 mmol·g-1 of Ba2+ cations from 0.01 M BaCl2 solution, that in 3 times more than the adsorption of these cations by unmodified silica. It was found that the adsorption of cations by basic and modified silica is well described by the pseudo-second order Lagergren equation. The high adsorption activity of silica with chemisorbed TMS-groups is due to the formation of local regions with relatively large values of negative and positive electrostatic potentials in the vicinity of grafted TMS-groups.