ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Diusion of Ethanol Vapours in Activated Carbon Particles

D. Bobok and E. Besedová

Department of Chemical and Biochemical Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology, SK-812 37 Bratislava

E-mail: bobok@chtf.stuba.sk, besedova@cvt.stuba.sk

Received: 4 April 2002

Abstract: In adsorbers with a bed height equal to the diameter of activated carbon particles the course of stepwise adsorption of ethanol from a stream of air and the course of stepwise desorption of ethanol by a stream of air with a lower content of ethanol compared with adsorption or by a stream of pure air were examined. The stepwise measurements were performed at a concentration of ethanol in air ranging from 0 to 0.35 mol m⁻³, which corresponds to the concentration of ethanol on activated carbon from 0 to 4180 mol m⁻³. From experimentally measured data effective diffusion coefficients D_e were calculated for each adsorption and desorption step. The calculated values of D_e are ranging from 1.182x10⁻¹⁰ to 6.308x10⁻¹⁰ m² s⁻¹. These values are dependent on the adsorbate concentration. From experimental data also values of D_e were calculated for each time of the stepwise adsorption and desorption. These values were used for the determination of the dependence of D_e on the adsorbate concentration:

D_e = −4.7424x10⁻²¹q³ + 5.6130x10⁻¹⁷q² − 5.9684x10⁻¹⁴q + 1.7647x10⁻¹⁰

By comparison of the obtained values of the e ective di usion coecient with values calculated by models it follows that during the transport of ethanol in particles of activated carbon Supersorbon HS4 both Knudsen di usion and surface di usion are decisive.

Full paper in Portable Document Format: 571a39.pdf

Chemical Papers 57 (1) 39–44 (2003)