MODELLING OF THE INTERACTION OF NITROGEN DIOXIDE WITH ACTIVATED CARBON I. ADSORPTION DYNAMICS AT THE SINGLE PARTICLE SCALE

Abstract

The adsorption dynamics of nitrogen dioxide on activated carbon are measured using a microbalance technique. A theoretical model, incorporating the mechanisms of micropore, macropore and concentration dependent sorbed phase (surface) diffusion, with nonlinear equilibrium (dual Langmuir isotherm), is fitted to the experimental NO₂ adsorption dynamics over a range of temperatures, concentrations and particles sizes. The data are well fitted by the model over the temperature range 298–373 K, with typical extracted values of the diffusivities at 298 K being: D/R ² _μ=0.003 s⁻¹1 (micropore), D _p = 0.038 cm²/s (macropore) and D _so=1.0 × 10⁻⁶cm²/s (surface) with micropore and surface diffusion activation energies of 14.8 and 11.0 kJ/mole, respectively. The influence of the NO₂/N₂O₄ ratio on the adsorption dynamics is also discussed. At temperature higher than 373 K, significant reaction of NO₂ with activated carbon results in consumption of the carbon.

KEYWORDS:

• Macropore
• Micropore and concentration dependent surface diffusion

Additional information

Notes on contributors

P.G. GRAY

Present address: LIMSI-CNRS, BP 133, F-91403 Orsay Cedex, France

D.D. DO

Author to whom correspondence should be addressed.