Organic vapours sorption on simply modified bentonites

Abstract

Modified materials based on bentonite (acid-activated bentonite, mineralogically defined clay obtained by sedimentation, and composite material composed of bentonite and humic substances) were prepared in this work and sorption properties of the prepared materials for organic vapours (cyclohexane, toluene, mixture of xylenes and acetone) were determined. The aim of modification was the specific surface area enlargement and reduction of hydrophilic character. Results of the organic vapours adsorption show that the polarity of adsorbate is very important factor. It was found that adsorption of less polar and nonpolar organic vapours on the prepared clay-based materials took place through weak interactions and the specific surface area was key factor influencing adsorption process. Influence of water content in the materials can be considered, too. Adsorbed amounts of weakly polar organics on the clay materials were at most on the half level in comparison with active carbon. In the case of polar acetone the studied bentonites show the comparable adsorbed amounts as active carbon. It was found that acetone replaced water molecules in the solvation shells of interlayer cations, which was proven by infrared spectroscopy. The specific surface area did not play a leading role during adsorption of acetone on the bentonites.