Influence of pH, concentration and ionic strength during batch and flow-through continuous stirred reactor experiments of Sr2+-adsorption onto montmorillonite

Abstract

Sorption/desorption experiments in batch and continous flow-through stirred reactor under different experimental conditions were carried out using montmorillonite (\2 lm clay fractions). The Sr 2? amount desorbed at pH 4 is only half of the amount desorbed at pH 8, revealing that the retention of Sr 2? onto montmorillonite was enhanced at pH 4. The largest adsorption value was obtained at pH 8.0 ([KNO 3 ] = 10 -3 mol/L) with q m = 41.49 mg Sr 2? /g from the Langmuir isotherm. The gradient of concentration acted as an increasing driving force since the amount of Sr 2? adsorbed increased as increasing of Sr 2? concentration during the flow-through experiments.

Adsorption of strontium and caesium onto an Na-MX80 bentonite: Experiments and building of a coherent thermodynamic modelling

“…The adsorption onto bentonite, as for many clay minerals (Carroll, 1959), is mainly controlled by an ion-exchange mechanism. Semi-empirical approaches of these adsorption mechanisms onto bentonite were used (Dyer et al, 2000;Guimarães et al, 2015;Mahoney and Langmuir, 1991;Rafferty et al, 1981;Shaban and Macášek, 1998), but few works used a mechanistic, or semi-mechanistic, approach. Bradbury and Baeyens (1999) have developed a model based on a mechanistic description of the cation adsorption between a clay minerals and a liquid phase-namely the two-site protolysis non-electrostatic surface complexation and cation exchange model or 2SPNE SC/CE.…”