A BET approach to multilayer adsorption in swelling products Original Research Article

An equation for multimolecular sorption is presented. It is based on the BET model with the assumption that the adsorbing surface can be divided in two regions: A region that supports only a limited number of adsorbed layers due to geometric restrictions, and another region that can adsorb an unlimited number of layers. The proposed equation is applicable to type 2 and 3 isotherms (BDDT classification), and was successfully used to fit water sorption equilibrium data of some foodstuff from literature for the water activity range 0.05–0.90, and a temperature range from 10 to 70 °C.