The effect of the mineralogical composition of various bentonites on CEC values determined by three different analytical methods

Choo, Ko-Yeon; Bai, Kang

doi:10.1016/j.clay.2016.03.010

Cited by 29 publications

(13 citation statements)

References 14 publications

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“…The results for sodium, calcium, lanthanum, and iron, presented in Table 1, demonstrate that Na + and Ca 2+ were changed by La 3+ and Fe 3+ . The values of cation exchange capacity (CEC) presented in Table 1 for the precursor clay minerals were within the range expected for bentonites/montmorillonites 0.60-0.80 eq kg -1 , [51][52][53] with 0.68 and 0.61 eq kg -1 for Bent and PetBent, respectively. This characteristic agrees with the percentages of exchangeable cations determined by WD-XRF (Na 2 O and CaO): 2.61% for Bent and 2.11% for PetBent.…”

Section: Preparation and Characterizations Of The Clay Mineralssupporting

confidence: 72%

Phosphate Adsorption by Montmorillonites Modified with Lanthanum/Iron and a Laboratory Test using Water from the Jacarepaguá Lagoon (RJ, Brazil)

Castro

Brandão

Bertolino

et al. 2018

J. Braz. Chem. Soc.

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Montmorillonites modified with lanthanum(III) and iron(III) were prepared from two commercial clays. These materials were characterized by powder X-ray diffraction analysis, X-ray fluorescence, infrared spectroscopy, N 2 adsorption, and scanning electron microscopy. The incorporation of lanthanum(III) and iron(III) varied from 0 to 4.00%. The amount of these cations governed the adsorption capacity of the material since an increase in the percentage of La by 1.7 times improved the adsorption capacity by 3.3 times. The structural properties of the precursor clay minerals, such as pore size, may have influenced the extension of the modification process. Kinetics and equilibrium studies indicated that adsorption occurs mainly within 24 h, and the pseudo-second order and Lagmuir models described the process. The phosphate adsorption capacity ranged from 2.86 to 17.86 mg g-1 for the modified materials and was mainly dependent on the La content. A laboratory test with a natural water sample from the Jacarepaguá Lagoon showed reduction of the soluble reactive phosphorus concentration from 0.41 to 0.04 mg L-1 , for the material with 4.00% La 2 O 3. The materials described in this work were effective for the reduction of the soluble reactive phosphate, contributing to the research of a national product destined to the restoration of eutrophic aquatic environments.

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Section: Preparation and Characterizations Of The Clay Mineralssupporting

confidence: 72%

Phosphate Adsorption by Montmorillonites Modified with Lanthanum/Iron and a Laboratory Test using Water from the Jacarepaguá Lagoon (RJ, Brazil)

Castro

Brandão

Bertolino

et al. 2018

J. Braz. Chem. Soc.

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“…The Trp-Na-bent materials were prepared according to a modified literature method (Marsal et al, 2009). The cation exchange capacity (CEC) of Na-bent (98.37 meq/100 g) was calculated by the classical BaCl 2 /MgSO 4 method (Choo and Bai, 2016). The Na-bent was dispersed at 1% (w%) in a solution containing L-Trp (0.20 g/g of clay) with the amount equivalent to 1 time of CEC of Na-bent.…”

Section: Purification and Modification Of The Bentonitementioning

confidence: 99%

Removal of Synthetic Estrogen from Water by Adsorption on Modified Bentonites

Gallouze

Akretche

Daniel

et al. 2021

Environmental Engineering Science

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Natural bentonite is an adsorbent that can be easily modified as a low-cost material effective for the removal of persistent pharmaceutical micropollutants from water bodies. In this study, the modification of untreated bentonite by sodium is addressed to obtain Na-bent, which was further modified with L-Tryptophan (L-Trp) as well as with FeCl 2 .4H 2 O to produce Trp-Na-bent and Fe-Na-bent, respectively. The nonmodified and modified bentonite samples were tested for the adsorption of the pharmaceutical micropollutant 17aethinylestradiol (EE2) present in water bodies, a synthetic estrogen with very high toxicity. The structure of bentonite, before and after modification, was characterized using Fourier transform infrared, X-ray diffraction, Brunauer-Emmett-Teller, and thermal analysis (thermogravimetric analysis and differential scanning calorimetry) techniques. The influence of various experimental parameters on the adsorbent/adsorbate interaction was investigated. Equilibrium and kinetic studies of EE2 micropollutant adsorption were performed varying the initial adsorbate concentration, mass of bentonite, and contact time. The maximum adsorption for an initial concentration of 10 mg/L of EE2 was 4.20 mg/g, reaching the equilibrium after 2 h. The equilibrium data were fitted with Langmuir, Freundlich, and Dual-mode model equations. Adsorption kinetic data were analyzed using the pseudo-first order, pseudo-second order, and intraparticle diffusion models. The pseudosecond order model was the one that better described the kinetic data. The highest value of the equilibrium rate constant was obtained for Trp-Na-bent, followed by Fe-Na-bent. The results obtained show that the Trp-Na-bent complex exhibits a promising performance for the adsorption of EE2.

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“…Além disso, é importante ressaltar que a liofilização promoveu um incremento de 32,3% na capacidade de inchamento da bentonita sódica mais ativa. Acredita-se que o processo possa ter aumentado A segunda ocorreu em torno de 650 °C e correspondeu à reação de desidroxilação (pico endotérmico) [32]. Segundo a Agência Nacional de Vigilância Sanitária (ANVISA), a contagem de microrganismos mesófilos aeróbios totais não deve ultrapassar o valor de 500 UFC/g para produtos de uso infantil, para área dos olhos e que entram em contato com mucosas, ou de 5000 UFC/g para demais produtos cosméticos [33].…”

Section: Resultsunclassified

Estudo do comportamento e caracterização de argilas bentoníticas após processo de liofilização

et al. 2018

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Resumo Bentonita é um tipo de argila composta principalmente de montmorilonita. Possui excelentes propriedades de adsorção e como principais características a alta capacidade de troca catiônica, capacidade de inchamento, grande área superficial e baixa condutividade hidráulica. A bentonita é utilizada como matéria-prima em mais de 40 aplicações industriais. O processo de liofilização consiste na secagem de um produto, passando pela etapa de sublimação, para remoção da água contida utilizando baixa pressão e impedindo qualquer atividade biológica e reações químicas. Ele é eficiente em características como contração do produto, perda de voláteis, decomposição térmica, ações enzimáticas e desnaturação de proteínas, se comparado com outros meios de desidratação, ou seja, mantém a integridade do produto. Neste trabalho, foi avaliado o comportamento e realizada a caracterização de bentonita sódica mais ativa e sódica menos ativa, antes e após o processo de liofilização. Considerou-se como mais ativa a bentonita que apresentou maior capacidade de troca catiônica - CTC relacionada aos íons sódio (Na+). Foram feitas análises químicas e mineralógicas, de capacidade de troca catiônica, análise microbiológica, FTIR e capacidade de inchamento. Observou-se um incremento de aproximadamente 32% na capacidade de inchamento da bentonita mais ativa após a liofilização.

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The effect of the mineralogical composition of various bentonites on CEC values determined by three different analytical methods

Cited by 29 publications

References 14 publications

Phosphate Adsorption by Montmorillonites Modified with Lanthanum/Iron and a Laboratory Test using Water from the Jacarepaguá Lagoon (RJ, Brazil)

Phosphate Adsorption by Montmorillonites Modified with Lanthanum/Iron and a Laboratory Test using Water from the Jacarepaguá Lagoon (RJ, Brazil)

Removal of Synthetic Estrogen from Water by Adsorption on Modified Bentonites

Estudo do comportamento e caracterização de argilas bentoníticas após processo de liofilização

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