Adsorption Kinetics and Equilibria of Strontium onto Kaolinite

Abstract

Adsorption of Sr 2+ onto kaolinite has been studied by means of a radiotracer technique using the 90 Sr isotope. Bangham's and McKay models have been applied to kinetic results in Sr 2+ concentrations between trace −0.1 mol.L −1 . The magnitudes of film and intra-particle diffusion coefficients are 10−10 and 10−14 m 2 ·s −1 , respectively. Concentration dependence of diffusion coefficients indicated that Sr 2+ ions are adsorbed on two different adsorption sites by an exothermic and spontaneous process. The Freundlich isotherm parameters and exchange equilibrium constants derived from selectivity coefficients indicate that Sr adsorption are depressed by competing cations in the order of Na + < Mg 2+ < Al 3+ .

Strontium adsorption and penetration in kaolinite at low Sr2+concentration

“…Kaolinite is one of the most ubiquitous phyllosilicates in soils, and it has next to the basal plane surface a relatively large edge surface (White and Dixon 2002); therefore, Sr 2+ adsorption and transport in kaolinite soils deserve specific attention. Some reports consider Sr 2+ adsorption on kaolinite on the basis of ion exchange (Wahlberg et al 1965;Parkman et al 1998;Bascetin and Atun 2006;Keçeli 2015). Sr 2+ transport in quartz sand (Rod et al 2010), sediment (Wallace et al 2012) and porous material (Prigiobbe et al 2012) were reported.…”