Shape-selective adsorption of aromatic molecules from water by tetramethylammonium–smectite

Abstract

The adsorption of aromatic compounds by smectite exchanged with tetramethylammonium (TMA) has been studied. Aromatic compounds adsorbed by TMA–smectite are assumed to adopt a tilted orientation in a face-to-face arrangment with the TMA tetrahedra. The sorptive characteristics of TMA–smectite were influenced strongly by the presence of water. The dry TMA–smectite showed little selectivity in the uptake of benzen, toluene and xylene. In the presence of water, TMA–smectite showed a high degree of selectivity based on molecular size/shape, resulting in high uptake of benzene and progressively lower uptake of larger aromatic molecules. This selectivity appeared to result from the shrinkage of interlamellar cavities by water.