Validation of using a modified BET model to predict the moisture adsorption behaviour of bituminous coal.

Five coal samples were investigated from three different collieries in the major Witbank-Middelburg, Free State (Sasolburg-Vereeniging) and Limpopo region coalfields. A good correlation was found between the amount of moisture adsorbed and the oxygen content of medium-rank B vitrinite-rich and medium-rank C inertinite-rich bituminous coal. Total mass/g of moisture adsorbed as determined by the modified BET (Brunauer-Emmett-Teller) model provides a better approximation than the BET model, the relationship in the modified model between moisture monolayer coverage and the area of surface oxygen groups suggesting that moisture is adsorbed at these sites. Open hysterisis loops indicate that moisture is retained on the medium-rank C inertinite-rich bituminous coals.
Five coal samples were investigated from three different collieries in the major Witbank-Middelburg, Free State (Sasolburg-Vereeniging) and Limpopo region coalfields. A good correlation was found between the amount of moisture adsorbed and the oxygen content of medium-rank B vitrinite-rich and medium-rank C inertinite-rich bituminous coal. Total mass/g of moisture adsorbed as determined by the modified BET (Brunauer-Emmett-Teller) model provides a better approximation than the BET model, the relationship in the modified model between moisture monolayer coverage and the area of surface oxygen groups suggesting that moisture is adsorbed at these sites. Open hysterisis loops indicate that moisture is retained on the medium-rank C inertinite-rich bituminous coals.