Sorption of Naphthalene Vapor on Organomodified Vermicullite

Abstract

Organomodified clays are widely used in many applications, among others as sorption materials for nonpolar organic compounds from soils and aqueous media. Vermicullite is a clay that is still little  utilized. Its structure is similar to smectites with layered structure and interlayer space filled with inorganic cations. Vermicullites are known for their high negative charge in the layers and high cation exchange capacity. Therefore, natural vermicullites were organomodified by exchanging inorganic for organic cations. Vermicullites modified with hexadecyltrimethylammonium (HDTMA) and 1-hexadecylpyridinium (HDP) cations were prepared, characterized and tested in naphthalene vapor sorption.  HDTMA vermicullite  was a better sorbent for naphthalene vapor than the HDP analog. The HDTMA cations formed  a well ordered organic phase in the inner vermicullite gallery with sufficient space for naphthalene molecules. In contrast, the HDP cations formed disordered structure due to bulky  pyridinium rings and the presence of water from the monohydrate salt.