Journal of Colloid and Interface Science, Vol.319, No.1, 374-376, 2008
Adsorption of ions onto amorphous silica: Ion exchange model
Single site ion exchange model was applied for description of the published data on adsorption of sodium, calcium, cadmium, and zinc onto amorphous silica. The following equilibria were detected (25 degrees C) X-adsorption site; TotX = 6 mu mol/m(2)): 2X + Na+ + OH- double left right arrow XNa+ + XOH-, log K degrees = 5. 1, 3X + Me2+ + 2OH(-) double left right arrow XMe2+ + 2XOH(-), log K degrees = 11.6 (Ca), 11.7 (Cd), 2X + Me2+ + 2OH(-) double left right arrow XMeOH+ + XOH-, log K degrees = 14.1 (Cd), 15.5 (Zn). (C) 2007 Elsevier Inc. All rights reserved.