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Decolorization of vegetable oils; a study of the mechanism of adsorption of beta -carotene by an acid-activated bentonite from Cyprus

George E. Christidis and Sotiria Kosiari
Decolorization of vegetable oils; a study of the mechanism of adsorption of beta -carotene by an acid-activated bentonite from Cyprus
Clays and Clay Minerals (June 2003) 51 (3): 327-333

Abstract

The mechanism of decolorization of crude maize and sunflower oils was studied by means of adsorption of beta -carotene by a low-grade bentonite, containing 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 (super -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 (super -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 (super -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 (Bronsted 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.


ISSN: 0009-8604
EISSN: 1552-8367
Coden: CLCMAB
Serial Title: Clays and Clay Minerals
Serial Volume: 51
Serial Issue: 3
Title: Decolorization of vegetable oils; a study of the mechanism of adsorption of beta -carotene by an acid-activated bentonite from Cyprus
Affiliation: Technical University of Crete, Department of Mineral Resources Engineering, Chania, Greece
Pages: 327-333
Published: 20030601
Text Language: English
Publisher: Clay Minerals Society, Clarkson, NY, United States
References: 25
Accession Number: 2003-069980
Categories: Geochemistry of rocks, soils, and sedimentsSedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
N34°30'00" - N35°40'00", E32°30'00" - E34°30'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200321
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