Experimental determination and modelling of water desorption isotherms of tropical woods: Afzelia, Ebony, Iroko, Moabi and Obeche

Desorption isotherms of Afzelia, Ebony, Iroko, Moabi and Obeche have been experimentally found at 20, 30, 40, 50 and 60 degrees C by use of the salt method for a range of water activities from 0.06 to 0.97. The sorption capacity of these woods increases with the temperature for a given water activity. The experimental curves have been simulated by the GAB and BET models. The GAB model enables the representation of the whole desorption isotherms. Meanwhile, the BET model ensures a better representation of the experimental results for water activity lower than 0.35 with mean relative deviation of 2.9, 2.1, 1.3, 3.2 and 3.3% for respectively Afzelia, Ebony, Iroko, Moabi and Obeche and a better estimation of the water content corresponding to monolayer saturation.