Particles with large specific surface areas are mostly porous and this may request larger equilibration times than for non-porous particles. With adsorption from solution also the stirring/shaking conditions are important. With N2 gas adsorption at 77 K for BET analysis there should be no problem with macro- and meso-porous particles, but with microporous particles (pores < 2nm) equilibration may take a long time and it might be better to use CO2 at 0 oC.

Mohamed Gamal Simeda

Specific surface area (SSA) is only one of the characteristics of the adsorbent. There are other important factors, more importantly, the surface chemistry of the adsorbent, physicochemical properties of the adsorbate, and the experimental conditions (solution pH, ionic strength, temperature, mixing, etc.), which need to be duly considered. I do not think there possibly exists such a universal relationship which could simplistically relate kinetics with the SSA alone, of all the adsorbate-adsorbent systems in the world.

Of course the detailed kinetics depend on the system. For non-porous systems we have film diffusion and the surface reactions; with porous surfaces we have these processes also but extra is the diffusion in the pores and when there are small meso pores and/or micropores this pore diffusion is a relatively slow process.

I agree with dr. Luuk K. Koopal. Please be aware that the specific surface area measured through the BET method is not a real surface but it is based on conventions, and it doesn't tell us anything about the pore size distribution which is more important. If your sample contains a significant amount of microporosity (pores with openings of