Determination of the Interaction Capacity of Silica Gel by Gas-Solid Chromatography and Titration Calorimetry

Abstract

Dispersive and specific adsorption energies resulting from adsorption of alkanes and basic probes on silica gel (Fischer, lot 712393 60/200 mesh) were determined respectively by gas-solid chromatography and titration calorimetry. These adsorption energies are related to the inkraction capacity of silica gel. Fitting the adsorption energies to Snyder-Karger and modified Drago interaction models, the interaction capacity can be quantified by four interaction capacity parameters, i.e., the two Hansen partial cohesion parameters (MPa'") Bd,s (dispersive) = 18.60 f 0.42 and B,,s (polar) = 5.01 f 6.16, and the two Drago parameters (H'" mol-') ES (electrostatic) = 7.73 f 2.63, and CS (covalent) = 2.53 f 0.18, with CIE = 0.33. These values are in very good agreement with the currently used scale. The adsorption energies, calculated in return, compare well with the experimentally determined values and give at the same time different components (dispersive, polar, and hydrogen bonding) of the total interaction energies.

Estudo da Determinação dos Grupos Silanóis ( º Si-OH) em Sílica: Aplicação à Materiais de Recheio Utilizados em Cromatografia Gasosa

“…Alguns métodos químicos [6][7][8][9][10][11][12][13][14][15][16][17][18][19] e espectroscópicos 20-26 podem ser usados para identificar quantidades relativas dos grupos silanóis e até eliminá-los 27 . Entretanto, a literatura ainda é deficitária no que diz respeito à determinação destes grupos de uma forma simples e fácil de realizar em laboratório químico.…”