Thermodynamic Study on the Adsorption of Some Organic Acids From Aqueous Solutions by Unmodified and Modified Montmorillonite Clays

Freitas, Alessandra Fequetia; Mendes, Marisa Fernandes; Coelho, G. L. V.

doi:10.1080/00986440802668232

Cited by 13 publications

(5 citation statements)

References 23 publications

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“…This is because as the concentration of fatty acid increases, a greater number of hydrogens of the fatty acid molecule are available per gram of the fatty acid to interact with the loan pair of electrons on the nitrogen group per gram of resin. Freitas et al have studied the adsorption of organic acids from aqueous solutions by unmodified and modified montmorillonite clays. It has been reported that the adsorption capacity of the adsorbents increased with an increase in the initial concentration of the adsorbate due to the enhancement in the driving force, which allows the movement of organic acids molecules from the bulk solution to the adsorbent surface, thus overcoming the mass transfer resistance between phases and increasing the overall flux.…”

Section: Resultsmentioning

confidence: 99%

“…It has been reported that adsorption of fatty acids on montmorillonite adsorbent follows the Langmuir isotherm, and the obtained parameters indicate that the adsorption process is dominated by physical forces. Freitas et al investigated the modification of the surface of the montomorillonite by treating it with hexadecyltrimethylammonium bromide and its subsequent application for the adsorption of organic acids. It has been reported that the modified montomorillonite has higher adsorption capacity as compared to the unmodified montomorillonite due to the presence of organic cation among the layers in the modified form.…”

Section: Introductionmentioning

confidence: 99%

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Adsorptive Removal of Saturated and Unsaturated Fatty Acids Using Ion-Exchange Resins

Maddikeri

Pandit

Gogate

2012

Ind. Eng. Chem. Res.

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One of the pretreatment approaches for decreasing the initial acid content of waste vegetable oil or nonedible oils with high initial free fatty acid content, with an objective of obtaining a suitable starting raw material for the production of biodiesel, is the adsorption of the free acids using ion-exchange resins. The present work deals with investigation of adsorption characteristics of saturated (stearic) and unsaturated (oleic) fatty acids on different ion exchange resins (polymeric strong (Indion 810) and weak (Indion 850 and Indion 860) anion exchange resins). The ion exchange resins contain tertiary or quaternary amino functional groups on the styrene-divinyl benzene copolymer matrix which can facilitate the adsorption of acids. Kinetic adsorption studies have been carried out initially to determine the contact time required to reach the adsorption equilibrium between fatty acid adsorbed on the resin and remaining fatty acid present in the oil. Equilibrium adsorption studies have been carried out at different temperatures viz. 293, 303, and 313 K. It has been observed that adsorption of saturated and unsaturated fatty acids increased with its concentration in the liquid at constant temperature and decreased with an increase in the temperature at constant concentration. Also, the adsorption equilibrium data have been found to be well described by the Freundlich type isotherm. The negative values of ΔG and ΔH showed that the adsorption of both saturated and unsaturated acids on the ion exchange resins was spontaneous and also exothermic.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Adsorptive Removal of Saturated and Unsaturated Fatty Acids Using Ion-Exchange Resins

Maddikeri

Pandit

Gogate

2012

Ind. Eng. Chem. Res.

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“…This confirms a favorable adsorption system. There are many theories relating to adsorption equilibrium [7], [8], [9].The isotherms of the oil adsorption by activated carbon and zeolite were represented by applying the Freundlich and Langmuir adsorption models.…”

Section: Adsorption Isothermsmentioning

confidence: 99%

Oily Wastewater Treatment Using Expanded Beds of Activated Carbon and Zeolite

Mohammed¹,

Faisal²,

Alwan³

2011

IJCPE

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Two types of adsorbents were used to treat oily wastewater, activated carbon and zeolite. The removal efficiencies of these materials were compared to each other. The results showed that activated carbon performed some better properties in removal of oil. The experimental methods which were employed in this investigation included batch and column studies. The former was used to evaluate the rate and equilibrium of carbon and zeolie adsorption, while the latter was used to determine treatment efficiencies and performance characteristics. Expanded bed adsorber was constructed in the column studies. In this study, the adsorption behavior of vegetable oil (corn oil) onto activated carbon and zeolite was examined as a function of the concentration of the adsorbate, contact time, adsorbent dosage and amount of coagulant salt(calcium sulphate) added . The adsorption data was modeled with Freundlich and Langmuir adsorption isotherms. and it was found that the adsorption process on activated carbon and zeolite fit the Freundlich isotherm model. The amount of oil adsorbed increased with increasing the contact time, but longer mixing duration did not increase residual oil removal from wastewater due to the coverage of the adsorbent surface with oil molecules. It was found that as the dosage of adsorbent increased, the percentage of residual oil removal also increased. The effects of adsorbent type and amount of coagulant salt(calcium sulphate) added on the breakthrough curve were studied in details in the column studies. Expanded bed behavior was modeled using the Richardson-Zaki correlation between the superficial velocity of the feed stream and the void fraction of the bed at moderate Reynolds number.

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“…Adsorbent treatment has the advantages of reduced oil losses and soap contamination [22]. However, there are a few studies investigating the adsorption of FFA on adsorbents such as different types of clay: montmorillonite, sepiolite, kaolinite cristobalite and bentonite [23][24][25][26][27][28]. Recently, there are some studies on the adsorption of free fatty acids using anion resins [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

FFA Adsorption from Waste Oils or Non-Edible Oils onto an Anion-Exchange Resin as Alternative Method to Esterification Reaction Prior to Transesterification Reaction for Biodiesel Production

Díaz¹,

Brito²

2016

J Adv Chem Eng

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Biodiesel is an alternative source of energy in diesel engines in its neat form or as a blend with conventional diesel fuel. The raw feedstock costs represent a lot of the overall biodiesel production cost. Therefore, the employment of waste oils or non-edible oils (which do not compete with edible oils) as feedstock for biodiesel production are presented as the best alternative. However, the presence of free fatty acids (FFA) in these oils is undesirable for biodiesel production due to the transesterification reaction performance is reduced. Hence, in this paper, the adsorption as treatment for reducing or removing FFA from oils prior to transesterification reaction for biodiesel production is examined using a strong anion-exchange resin in order to avoid esterification reaction employed commonly prior to transesterification reaction. Journal of Advanced Chemical Engineering

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Thermodynamic Study on the Adsorption of Some Organic Acids From Aqueous Solutions by Unmodified and Modified Montmorillonite Clays

Cited by 13 publications

References 23 publications

Adsorptive Removal of Saturated and Unsaturated Fatty Acids Using Ion-Exchange Resins

Adsorptive Removal of Saturated and Unsaturated Fatty Acids Using Ion-Exchange Resins

Oily Wastewater Treatment Using Expanded Beds of Activated Carbon and Zeolite

FFA Adsorption from Waste Oils or Non-Edible Oils onto an Anion-Exchange Resin as Alternative Method to Esterification Reaction Prior to Transesterification Reaction for Biodiesel Production

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