Adsorptive bleaching of soybean oil with non‐montmorillonite Zambian clays

Habile, Michael; Barlow, Philip J.; Hole, M.

doi:10.1007/bf02636072

Cited by 13 publications

(10 citation statements)

References 15 publications

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“…Indeed, weak acid treatments are generally ineffective for activating all the sites of adsorption of clays during the activation period. On the other hand, when clays undergo severe acid leaching (strong concentrations of acid), this contributes quite simply to the destruction of their crystalline structure, with subsequent formation of oxides of alumina and silica [8,[23][24][25]. This would probably explain the very low reactivity of clay A2M.…”

Section: Kinetics Of the Adsorption Of The Pigmentsmentioning

confidence: 99%

“…The results presented here on the adsorption of free fatty acids are against the results reported in former works. Indeed, it is generally found or admitted in the literature that the acid values of vegetable oils increase during discolouration [8,9,23]. This difference could be due to either the nature of the adsorbents or to the temperatures at which the experiments were performed.…”

Section: Kinetics Of the Adsorption Of Free Fatty Acidsmentioning

confidence: 99%

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Adsorption of pigments and free fatty acids from shea butter on activated Cameroonian clays

Mbah¹,

Kamga²,

Nguetnkam³

et al. 2005

Eur. J. Lipid Sci. Technol.

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Adsorption of pigments and free fatty acids from shea butter on activated Cameroonian claysAdsorption of pigments and free fatty acids from shea butter on acid-activated Cameroonian local clays was investigated. The adsorption of the pigments was followed by the reduction of the absorbance of the shea butter at 295 nm. The kinetic study revealed that both the temperature at which the experiment was performed and the degree of activation of the clays influence the time of contact required to reach adsorption equilibrium of the pigments and the amount of pigments adsorbed. Thus, at 90 7C, the time required was 30 min for the clays activated with 0.5 M (A0.5M) and 1.0 M solutions (A1M) of sulphuric acid, and 45 min for the clay activated with a 2.0 M solution (A2M) of sulphuric acid. At 80 7C, the adsorption equilibrium was reached after 45 min for clays A0.5M and A1M, and 60 min for clay A2M. At 65 7C, the contact time to reach adsorption equilibrium was longer than 75 min for all the adsorbents used. At 90 7C, the amount of pigments adsorbed at equilibrium by clay A2M was about two thirds of that adsorbed by clay A0.5M, and one half of the amount adsorbed by clay A1M. For each adsorbent, the amount of pigment adsorbed decreased with temperature. A1M was the most efficient local clay for the adsorption of shea butter pigments and compared favourably with the industrial clay used as reference. The same evolution was observed with the adsorption of free fatty acids on different clays. The contact time needed for the elimination of peroxides was 40 min for all the clays used. The most efficient adsorbents for the adsorption of the pigments and free fatty acids were also the ones that gave the best results in the elimination of peroxides. The energy of activation for the adsorption of the pigments, as determined by the adsorption kinetic model of Brimberg, were 61 6 9 kJ/mol, 73 6 11 kJ/mol, 67 6 10kJ/mol, and 47 6 7 kJ/ mol for the industrial adsorbent (EN) and clays A0.5M, A1M and A2M, respectively. These values of activation energies indicate that the shea butter pigments are chemisorbed on acid-activated clays. It was found that the adsorption isotherms follow the Freundlich equation.

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Section: Kinetics Of the Adsorption Of The Pigmentsmentioning

confidence: 99%

Section: Kinetics Of the Adsorption Of Free Fatty Acidsmentioning

confidence: 99%

Adsorption of pigments and free fatty acids from shea butter on activated Cameroonian clays

Mbah¹,

Kamga²,

Nguetnkam³

et al. 2005

Eur. J. Lipid Sci. Technol.

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“…There exist different industrial applications for clay minerals. They are important raw materials for the production of ceramics, bleaching earths for the wine and oil manufacturing industry for clarification and stabilization [30][31][32][33][34], furthermore for molding sands and recycling and cleaning of water [8,35]. Moreover they are used as fillers or coatings (cosmetics, paper, plastic materials) [28] or as carrier for pesticides, insecticides or catalysts [8].…”

Section: Introductionmentioning

confidence: 99%

Adsorption and separation of proteins by a smectitic clay mineral

Ralla

Sohling²,

Riechers

et al. 2010

Bioprocess Biosyst Eng

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The adsorption of proteins by a smectitic clay mineral was investigated. The clay used in this study is a mixture of montmorillonite and amorphous SiO(2). Due to the high porosity the montmorillonite units are accessible for protein adsorption. The amorphous silica prevents the montmorillonite from swelling and allows column packing. Protein adsorption was performed at different pH under static conditions. Furthermore, static capacities were determined. The material reveals high adsorption capacities for proteins under static conditions (270-408 mg/g), whereby proteins are mainly adsorbed via electrostatic interactions. The Freundlich isotherm is suggested as an adsorption model. For desorption a pH shift was found to be most effective. Binding and elution of human serum albumin and ovalbumin were tested under dynamic conditions. Dynamic capacities of about 40 mg/g for ovalbumin at 764 cm/h were found. The clay mineral provides suitable properties for the application as cost-efficient, alternative separation material.

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“…pressure, P, and the residual substance, C, Equations 1 and 2 can be rearranged as follows (11): [5] [ 6] Although the Freundlich equation is an empirical model, it is widely used to describe adsorption in vegetable oil bleaching (12,13). The widespread use of the Freundlich equation for oil bleaching and other industrial processes can be justified for three reasons: (i) For practical purposes, the equation is adequate to describe nonlinear adsorption in a narrow range of adsorbate concentrations; (ii) the mathematical simplicity of the equation enables it to be used easily; and (iii) the Freundlich model describes adsorption processes on surface adsorption sites that are energetically heterogeneous (14), a condition commonly found in adsorption systems.…”

mentioning

confidence: 99%

“…The most important adsorbent used in bleaching fats and oils is bleaching earth or clay. Bleaching clay performs not only color removal but also the removal of trace metals, the adsorption of phospholipids and soaps, and the decomposition of oxidation products such as peroxides (1,(5)(6)(7).…”

mentioning

confidence: 99%

Adsorption isotherms in bleaching hazelnut oil

Bayrak

2003

J Americ Oil Chem Soc

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Adsorption isotherms in bleaching hazelnut oil were determined to investigate the applicability of the Langmuir and Freundlich equations and to elucidate the adsorption characteristics of oil on bentonite EY-09 (Bensan Co. Ltd., Edirne, Turkey). The degree of bleaching was monitored spectrophotometrically. Absorbance measurements were carried out to investigate the adsorption force of clay during bleaching of hazelnut oil with 0.3, 0.5, 0.7, and 0.9 wt% clay at 50, 60, 70, 80, and 90°C. Bentonite EY-09 was used as the bleaching clay (adsorbent). Plots of log(x/m) vs. log X e (for the Freundlich isotherm) and X e /(x/m) vs. X e (for the Langmuir isomtherm) were made (where x is the amount of pigment removed per unit mass of the adsorbent, m, and X e is the equilibrium concentration of the pigment). The Freundlich constants were found to increase with temperature for a given oil/bleaching agent ratio, showing the formation of more active sites on the adsorbent with a rise in temperature. Since the heat evolved during adsorption (0.32-1.03 kJ mol −1 ) was less than 20 kJ mol −1 , the forces between the adsorbent and adsorbate appeared to be van der Waals forces. This type of adsorption is defined as physical or van der Waals adsorption. The results obtained show good agreement with the Freundlich isotherm, indicating that the adsorption of the pigment from the oil proceeds by monolayer formation on the surface of the adsorbent.Crude oil is processed by degumming, alkali refining, bleaching, and deodorizing. Bleaching reduces chlorophylls, carotenoids, and peroxides by adsorbing pigments onto the bleaching medium (1,2).Many investigations have been conducted into the bleaching of vegetable oils with bleaching clays in industry (3,4). Nonmontmorillonite minerals (such as kaolinites and micas), synthetic minerals (such as zirconium phosphate), or types of three-layered aluminosilicates (1) are reportedly ineffective or inferior adsorbents. Although at present montmorillonite does seem to be the most effective adsorbent clay available in industry, evaluations of alternative cheaper sources have attracted great attention in recent years. The most important adsorbent used in bleaching fats and oils is bleaching earth or clay. Bleaching clay performs not only color removal but also the removal of trace metals, the adsorption of phospholipids and soaps, and the decomposition of oxidation products such as peroxides (1, 5-7).Two main types of adsorption on surfaces can usually be distinguished (7). In the first type, the forces are of a physical nature and the adsorption is relatively weak. The forces involved in this type of adsorption are known as van der Waals forces, and the adsorption is called van der Waals adsorption, physical adsorption, or physiosorption. The quantity of heat evolved during van der Waals adsorption is usually smallless than 20 kJ mol −1 . This type of adsorption is less important in catalysis, except for certain special types of reactions involving free atoms or radicals.In the second type of adsorpt...

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Adsorptive bleaching of soybean oil with non‐montmorillonite Zambian clays

Cited by 13 publications

References 15 publications

Adsorption of pigments and free fatty acids from shea butter on activated Cameroonian clays

Adsorption of pigments and free fatty acids from shea butter on activated Cameroonian clays

Adsorption and separation of proteins by a smectitic clay mineral

Adsorption isotherms in bleaching hazelnut oil

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