Abstract

Micron-grade natural vermiculite was modified by several physical and chemical treatments in order to increase the adsorption capacity of this material for B. A thermal exfoliation (T = 600°C) of pristine material, a chemical exfoliation through reaction with hydrogen peroxide (H2O2 35%), or grafting of a specific B complexant (i.e. N-methyl-D-glucamine: NMDG) led to an increase in the uptake of B at low initial concentrations of the aqueous solutions ([B] ≈ 5 mg L−1). The more efficient material is the NMDG-grafted clay, for which the adsorption uptake is four times greater than that of raw vermiculite, and reaches 0.04 mmol g−1. For all modified materials, the effect of the pH on B adsorption and the adsorption kinetics were studied and compared to raw vermiculite. Adsorption isotherms were also plotted and fitted well with the Freundlich equation.

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