Interaction of Methylene Blue with Reduced Charge Montmorillonite

Bujdák, Juraj; Komadel, Peter

doi:10.1021/jp9718515

Cited by 179 publications

(172 citation statements)

References 22 publications

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“…Hang and Brindley, 1970;Brindley and Thompson, 1970;Kahr and Madsen, 1995;Yariv and Lurie, 1971;Gessner et al, 1994;Cenens and Schoonheydt, 1988;Schoonheydt and Heughebaert, 1992), would not enable such agglomeration. The size of a MB cation is about the same as the average area per negative layer charge of one electron in smectites (Bujd~fk and Komadel, 1997;Bujdftk et al, 1998). The distribution of the negative layer charge controls the distances between the adsorbed neighboring MB cations at the smectite surface.…”

Section: Interaction Of Methylene Blue With Claysmentioning

confidence: 99%

Methylene Blue Interactions with Reduced-Charge Smectites

Bujdák

2001

Clays and clay miner.

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Abstract--The objective of this work was to prepare series of reduced-charge materials from different parent Li-saturated dioctahedral smectites, to investigate the effects of temperature, chemical composition and charge location in smectites on the charge reduction and to characterize reduced-charge smectites (RCSs) using methylene blue (MB) adsorption. The layer charge decrease, induced by Li fixation, is correlated with the trends in the spectra of MB-RCS dispersions in the visible region (VIS) spectra. Distribution of the negative surface charge of the clay minerals controls the distance between the adsorbed MB cations and thus affects the formation of MB dimers and higher agglomerates. Because each form of MB (monomer, dimer, higher agglomerate, J-aggregates) absorbs light at a different wavelength, the VIS spectra of MB depend sensitively on the charge density at the clay surface. Both cation exchange capacity (CEC) values and spectra of MB-clay dispersions clearly detect extensive reduction of the layercharge density in reduced-charge montmorillonites (RCMs) upon Li-thermal treatment. The extent of charge reduction depends on the temperature of the thermal treatment, as well as on the octahedral charge of the montmorillonite. Reduction of the layer charge proceeds to a much lesser extent for smectites with mainly tetrahedral charge and high Fe content (Fe-rich beidellite and ferruginous smectite). Both CEC data and MB spectra detect only a slight decrease of the layer charge density, which relates to the low octahedral charge of these minerals. Following heating at higher temperatures (120-160~ slightly higher Li fixation is indicated by CEC values; however, no charge reduction is confirmed by MB spectra. Release of protons accompanying Li + fixation in Fe-rich smectites heated at 180 or 200~ was detected in the spectra of MB-clay dispersions and confirmed by potentiometric titrations.

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Section: Interaction Of Methylene Blue With Claysmentioning

confidence: 99%

Methylene Blue Interactions with Reduced-Charge Smectites

Bujdák

2001

Clays and clay miner.

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“…Os espectros foram obtidos em intervalos de tempo t= 1 min, posterior a imersão do eletrodo em solução de NaCl 0,050 mmol L -1 , permitindo observar o aparecimento e a intensificação da banda de absorção do monômero protonado, espécie AMH 2+ em 750 nm [1,3,21]. A Figura 2b) apresenta os VCs obtidos para o filme preparado pela metodologia II-4, situação na qual a suspensão de argila é agitada simultaneamente na presença do surfactante e do AM (1% m/m); condições experimentais idênticas às da Figura 2a).…”

Section: Resultados E Discussõesunclassified

“…Essas plaquetas são constituídas de aluminossilicatos organizados, compostos pelos elementos de Si, Al e oxigênio, além de outros em menores proporções, como o Mg, Fe e Ca, com formula geral:(OH) 4 Si 8 (Al 3,34 Mg 0,66 )O 20 .…”

Section: Introductionunclassified

Estudo espectro eletroquímico de sistemas estruturados argila-corante

2003

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IntroduçãoArgilas são minerais de ocorrência natural no solo e apresentam características físico-químicas peculiares. São formadas por pequenos cristais, quase sempre na forma de plaquetas hexagonais, que se aglutinam para formar conglomerados. Quando em suspensão, em água, permite a separação de suas camadas lamelares e a intercalação de íons metálicos (metais pesados) e moléculas (solvente, moléculas orgânicas, etc.) [8]. O entendimento das propriedades de sistemas organizados, tais como: a formação de sistemas micelares, a presença de polieletrólitos interagindo com as argilas, a formação de sistemas vesiculares, e a grande aplicação industrial das argilas leva ao interesse pelo estudo de sistemas estruturados constituídos pelas argilas.Sistemas estruturados do tipo ResumoO comportamento eletroquímico e espectroeletroquímico do sistema montmorilonita-azul de metileno (MM-AM)/AM solução foi investigado empregando-se a técnica de voltametria cíclica e de transiente, I x t (corrente versus tempo) sobre eletrodo de vidro ITO modificado pela deposição mecânica de filmes do compósito MM-AM. Os filmes foram preparados empregando três procedimentos: 1-na ausência de CTACl (surfactante, cloreto de cetiltrimetilamônio); 2-com incorporação do CTACl à região interlamelar; e 3-na presença do CTACl, porém, não incorporado à região interlamelar. A técnica espectrofotométrica foi empregada para a caracterização e para o estudo eletrocrômico dos filmes formados. Os resultados experimentais permitiram observar que: i-os filmes preparados com a incorporação prévia do AM a região interlamelar fornecem uma resposta eletroquímica mais eficiente com o aparecimento de um par de picos bem definido; ii-a adição do CTACl, de forma geral permite a obtenção de filmes mecanicamente mais estáveis; iii-com a inclusão prévia do CTACl na região interlamelar não ocorre o aparecimento da forma protonada do AM (AMH + ); iv-na ausência da forma protonada o compósito não apresenta comportamento eletrocrômico.

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“…The interactions of MB with smectites and several series of RCMs have been studied in several works [4,5,7,[9][10][11]. MB molecular aggregation in RCM dispersions is introduced in this work in order to compare the metachromic properties of studied phenothiazine dyes and Pyr with that of the most frequently investigated MB.…”

Section: Methylene Blue Aggregationmentioning

confidence: 99%

“…Two main types of the molecular aggregates have been described in literature. The first type, called H-aggregates, is typical of a sandwich-type molecular association [7]. Electrostatic repulsion between interacting transition dipoles occurs in this case, which results in an increase of the excitation energy compared to a non-aggregated monomeric form.…”

Section: Introductionmentioning

confidence: 99%

Interaction of montmorillonite with phenothiazine dyes and pyronin in aqueous dispersions: A visible spectroscopy study

2009

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Abstract:Layer charge is one of the key parameters used for the characterisation of expandable clay minerals, smectites. It determines most significant properties of the material which are important from the industrial application point of view. This work is related to a novel method introduced to characterize the layer charge of smectites, based on using cationic organic dyes as molecular sensors. One xanthene and four phenothiazine cationic dyes were tested using reduced charge montmorillonites (RCMs) and compared with methylene blue, which has been used most frequently. The characterization of the charge was based on the formation of molecular assemblies (H-and J-aggregates) composed by dye cations, which were easily detectable using absorption spectroscopy in the UV/VIS spectrum. More detailed characterization of the spectra required calculations of second-derivative curves. For all of the reaction systems tested in this work, the molecular aggregation increased with the layer charge of RCMs. Slight to moderate differences in the formation of dye assemblies related to the differences in the molecular structures of the individual dye cations. For example, the molecular asymmetry of azure A brought about the formation of coexistent species of similar structures. The structure of the heteroaromatic skeleton affected the extent of the aggregation and spectral changes with time. The presence of reactive, non-substituted amino groups in thionine cations probably partially decomposed in the clay mineral colloids based on high-charge RCMs. Any of the tested dyes could be used as molecular sensors for empirical characterization of the layer charge of clays taking into account the differences mentioned above.© Versita Warsaw and Springer-Verlag Berlin Heidelberg.

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Interaction of Methylene Blue with Reduced Charge Montmorillonite

Cited by 179 publications

References 22 publications

Methylene Blue Interactions with Reduced-Charge Smectites

Methylene Blue Interactions with Reduced-Charge Smectites

Estudo espectro eletroquímico de sistemas estruturados argila-corante

Interaction of montmorillonite with phenothiazine dyes and pyronin in aqueous dispersions: A visible spectroscopy study

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