Decolorization of vegetable oils: A study of the mechanism of adsorption of b-carotene by an acid-activated bentonite from CyprusDecolorization of vegetable oils: A study of the mechanism of adsorption of b-carotene by an acid-activated bentonite from Cyprus Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2015-10-012003enThe mechanism of decolorization of crude maize and sunflower oils was studied by means of adsorption of b-carotene by a low-grade bentonite , containin g mixed-layered illite-smectite. Decolorization depends on temperature and the time required for equilibrium decreases with increasing temperature. The study of the kinetics of adsorption showed that decolorization of maize oil is a first-order process which occurs in two steps: a first fast step with higher activation energy (25.6 kJ mol –1), indicating the influence of a chemical interaction between the pigment and the clay surface, followed by a second slow step with low activation energy (12.3 kJ mol –1), characteristic of physical adsorption on the previously adsorbed molecules. Decolorization of sunflower oil is also a first-order process, described by a single mechanism with intermediate activation energy (19.0 kJ mol –1). Adsorption isotherms of decolorization of maize oil follow the Freundlich equation, indicating the existence of heterogeneous adsorption sites on the solid’s surface. Heterogeneity is attributed both to different active centers on the smectite surface (Bro¨ nsted and Lewis centers) and to the different phases present in bentonite, such as illitic layers and clinoptilolite, which also have active centers on their surfaces.http://creativecommons.org/licenses/by/4.0/Clays and Clay Minerals351327–333CCM June 2003.pdfChania [Greece]Library of TUC2015-10-01application/pdf210.8 kBfree Christidis Georgios Χρηστιδης Γεωργιος Sotiria Kosiari Clay Minerals Society