Acta Agrophysica, 2004, 4(1), 115-122 RESTRAINS IN GAB EQUATION FOR DETERMINING ABSORBENT STRUCTURE Aneta Ocieczek, Piotr Palich Department of Hotel and Tourism Management, Gdynia Maritime Academy ul. Morska 83, 81-225 Gdynia e-mail: daszenka@am.gdynia.pl A b s t r a c t . The target of this publication is to present the restrains in the GAB model as a result of mathematical approach to the absorption process. In this study some difficulties in determining the structural characteristics of porous products with the use of the GAB model are presented. The problem to be solved can be used for cognitive and for application purposes as well. K e y wo r d s : hygroscopic products, parameters of structure, mathematical approach to the sorption process INTRODUCTION Structure and chemical composition play an important role in various physical and chemical surface processes which affect surface behavior under miscella- neous conditions. The surface of solids is heterogeneous, which is caused by its roughness. Moreover, its heterogeneity is affected by chemical composition which influences the adsorption processes [4,7,9,10,11]. In the quantitative approach, the surface structure as well as the chemical composition may be determined using the various methods for surface testing. For this purpose, a method consisting in atomic excitation (molecules) within the superficial layers of the solid by the use of electrons, ions, molecules, photons, electric-and magnetic field etc. is advisable. The monitoring and analysis of substance atom response (molecules), makes it possible to determine the surface characteristics [4,15]. In spite of the fact that the adsorption-based methods are improved all the time and may be even characterized by high resolution [4,9,10,17], the determi- nation of the surface structure through the gas adsorption method assures a very general view of surface structure.