Estudos de isotermas no processo de adsorção – revisão

Abstract

Due to the development of civilization and industrial expansion, some side effects – such as environmental pollution – appear and worsen. In parallel, there are procedures that seek to remedy such degradation, such as the adsorption process. Adsorption can be defined as a mass transfer process, which exploits the ability of certain solids to concentrate on their surface specific substances contained in aqueous solutions or gases. The substance that is adsorbed is called adsorbate and the material it adsorbs is called the adsorbent. The study and application of the adsorption process is carried out by the adsorption isotherms, which, in turn, translate into the variation of the degree of coating with the concentration (or pressure) at constant temperature. The correct interpretation of the isotherms requires the pre-determination of a specified adsorption mechanism, described by means of a corresponding model, which varies according to specific conditions, such as pore size, adsorption process mechanism, adsorbate properties and its affinity with the adsorbent. Among the most common isothermal models we can mention those of Langmuir, Brunauer-Emmett-Teller (BET), Sips, Koble-Corrigan, Temkin, among others. Thus, a bibliographic review of these five isotherms is carried out, taking into account their deductions, conditions of applicability and possible deficiencies of the models.