Transport of Penetrants in the Macromolecular Structure of Coals Ii. Effect of Porous Structure on Pyridine Transport Mechanisms

Pyridine transport in 600-850μm coal particles occurs by a non-Fickian mechanism which shows coupling of both diffusion and relaxation phenomena. In lignites (with carbon content less than 75%) the phenomenological pyridine transport mechanism is predominantly Fickian, whereas in bituminous coals (above 75% carbon) it approaches Case-II transport. However, when the porous structure of the coals is taken in consideration the true pyridine transport mechanism is Case-II transport.