Characterization of the Grafted Bentonite Supports by Gas Chromatography

Abstract

Gas chromatographic analysis technique was used for characterization of the gas chromatographic supports, which prepared from siliceous or natural origin. We studied the bentonite to be used as gas chromatographic support, which consists of aluminosilicate oxides mixture with some other
metallic oxides. It possesses a porous structure, which permits its use in
gas chromatography. The bentonite was thermally treated at 650ºC to
obtain firm granules, and acid washed by 6N-HCl to remove the soluble
metallic oxides especially iron oxide, till white granules with mesh range
100-120, were obtained. The specific surface area of the support was
measured to be 5.4 m²/g. The superficial structure of the grafted bentonite
by silicone SE-52 and dimethylchlorosilane was studied by "inverse gas
chromatographic method" using dichloromethane as auxiliary solute plotting
log V_s = f( 1/T). We carried out many separations for different mixtures
as cyclic and aromatic compounds and normal hydrocarbons. The grafted
bentonite supports permit to obtain analytical results characterized with
complete and good resolution with high efficiency and reproducibility for
all studied columns packed with silicone SE-52 and dimethylchlorosilane
grafted bentonite, compared with packed columns with bare bentonite.