Adsorptie van Al-ionen aan het kleimineraal montmorilloniet

The adsorption of aluminium ions onto sodium and calcium montmorillonite was studied. Under the experimental conditions (pH 3.5 and 5 and different total salt concentrations) the adsorbed aluminium ions were found to be in the form Al 3+, except when adsorbed onto calcium montmorillonite at pH 5. The similarity of the adsorption isotherms of Al 3+and La 3+onto montmorillonite and the similarity of these adsorption isotherms to the adsorption isotherms of Al 3+and La 3+onto resin (Dowex) suggested that adsorption properties of Al 3+onto montmorillonite were due to electrostatic properties and not to a specific property of aluminium nor of montmorillonite. Thermodynamic exchange constants ( K ) and the 'water factor' (responsible for dependence of K on concentration) were calculated. The 'water factor' corrected most of the variation in K .A hypothesis was developed and confirmed by experimental results. It resolved contradictions in the literature on the hydrolysis of aluminium ions in the presence of clay minerals. The influence is mentioned of the adsorbed aluminium ions on the cation-exchange capacity, the titration curve and the stability of clay mineral aggregates

Soil chemistry: a basic elements

xiv, 281 hlm.: ill.; 25 cm