GAS-ADSORPTION ISOTHERMS FROM COMPOSITION AND FLOW-RATE TRANSIENT TIMES IN CHROMATOGRAPHIC COLUMNS .2. EFFECT OF PRESSURE CHANGES

In the previous paper a method was described for measuring binary adso rption isotherms by a chromatographic method. The method involved maki ng simultaneous small perturbations to the concentration and flow-rate of the stream entering a packed column and observing the changes with time of the composition and flowrate of the gas leaving the column. T he perturbation to the inlet flow was made by adding a small extra str eam of gas of known composition to the main flow passing through the c olumns. The present paper describes the effect of the increased mean p ressure in the column caused by the small increase in flow. The effect is surprisingly large. A correction term is derived to compensate for the effect of increased pressure. By reanalysing the results for argo n-nitrogen reported in Paper I it is shown that instead of two differe nt isotherms being obtained by making the perturbation with the additi on of argon or nitrogen, a single isotherm for each component is obtai ned.