DETERMINATION OF THE INTERACTION CAPACITY OF SILICA-GEL BY GAS-SOLID CHROMATOGRAPHY AND TITRATION CALORIMETRY

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 tit ration calorimetry. These adsorption energies are related to the inter action capacity of silica gel. Fitting the adsorption energies to Snyd er-Karger and modified Drago interaction models, the interaction capac ity can be quantified by four interaction capacity parameters, i.e., t he two Hansen partial cohesion parameters (MPa(1/2)) delta(d,s) (dispe rsive) = 18.60 +/- 0.42 and delta(p,s) (polar) = 5.01 +/- 6.16, and th e two Drago parameters (kJ(1/2) mol(-1)) Es (electrostatic) = 7.73 +/- 2.63, and C-s (covalent) = 2.53 +/- 0.18, with C/E = 0.33. These valu es are in very good agreement with the currently used scale. The adsor ption energies, calculated in return, compare well with the experiment ally determined values and give at the same time different components (dispersive, polar, and hydrogen bonding) of the total interaction ene rgies.