Measurement of gas-adsorption equilibria via rotational oscillations

By using slow damped oscillations of a torsional pendulum, it is possible t o determine the mass adsorbed on the surface of a porous sorbent without bu oyancy effects from the frequency and the logarithmic decrement of the pend ulum motion. In principle, it is then possible to determine directly the bu oyancy-related volume V-as of the sorbent/sorbate system by combining the r esults with gravimetric measurements. Measurements with a preliminary testing pendulum are presented for N-2 and CH4 on the activated carbon Norit R1 Extra at ambient temperature in the pr essure range 0<p<0.5 MPa. Values for V-as calculated from these measurement s and gravimetrically determined data are presented and discussed to a cert ain extent.