ADSORPTION AND DESORPTION DYNAMICS OF SULPHUR DIOXIDE ON A SINGLE LARGE ACTIVATED CARBON PARTICLE

Abstract

A single particle sorption model based on dual diffusion processes (pore diffusion and diffusion of adsorbed species) with equilibrium (Freundlich isotherm) between the macropore fluid phase and the sorbed phase was developed. The model was fitted to experimentally determined adsorption and desorption of SO₂ on large (0.2 cm radius) activated carbon particles over a range of temperatures and SO₂ concentrations. The model fitted the experimental data well and typical extracted values of the macropore and surface diffusivities were 𝒟 _P = 0.038 cm²/s and 𝒟 _s = 1.0 × 10⁻⁵cm²/s at 25°C. The value of macropore diffusivity gave a macropore tortuosity factor of 8.0, whilst the temperature dependence of the surface diffusivity gave an activation energy of 5.0 kJ/mole.

KEYWORDS:

• Adsorption
• Macropore diffusion
• Surface diffusion
• Carbon
• Sulphur dioxide
• Freundlich isotherm