Abstract
The adsorption of water vapour on lead borosilicate glass has been studied at pressure region of 10-6mmHg by using the modified flash filament technique. The adsorbed amount and the kinetics of adsorption could be obtained by measuring the variation of pressure after rapid heating and cooling of the sample, and the apparatus used in this technique was the Beeck's calorimeter type cell in which the wire of resistance thermometer was employed as a heater. The sample glass was crushed to powder finer than 200mesh and coated on the inner wall of the cell. Using this method, it was possible to measure the physical and the activated adsorption separately.
The results showed that the adsorbed amount by the physical adsorption at 10-6mmHg, 050°C was 0.10.4% of monolayer, and the heat of adsorption was 11Kcal/mole. Most of the physical adsorption began below 50°C and the desorption occurred by heating at about 100°C150°C or by evacuation. With regard to the activated adsorption, the activation energy of adsorption was 9Kcal/mole and that of desorption was 1340Kcal/mole.
The residual gas pressure was about 510-9mmHg and the variation of pressure was measured by a sensitive (5×10-8mmHg/div.) Pirani gauge.
