Interaction Between Montmorillonite and Benzidine in Aqueous Solutions I. Adsorption of Benzidine on Montmorillonite

Lahav, N.; Raziel, S.

doi:10.1002/ijch.197100096

Cited by 16 publications

(9 citation statements)

References 12 publications

(17 reference statements)

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“…An adsorption maximum may be expected around pH 4.6 or higher which is probably close to the pKo, value. Lahav and Raziel (1971) measured the decrease of adsorption of benzidine from pH 7 to 9.3 and by combining their data with that of Dodd and Ray (1960), they expected the maximum adsorption to occur around pH 6. However, they concluded that there was no simple relation between the pKo and the pH of maximum adsorption, by taking pKb = 12.1 (i.e.…”

Section: Influence Of Controlled Ph On the Adsorption Of Benzidinementioning

confidence: 99%

“…ALTHOUGH the color reactions of benzidine, aniline and other aromatic amines with clay minerals, particularly montmorillonite, have been extensively studied, (see reviews by Theng, 1971;Lahav and Raziel, 1971) it is surprising that few quantitative adsorption studies have been made.…”

Section: Introductionmentioning

confidence: 99%

“…In their interpretation of the results, they assumed that only divalent and monovalent semiquinones undergo exchange reaction. Lahav and Raziel (1971) studied the adsorption of benzidine (not its hydrochloride) by montmorillonite from very dilute aqueous solutions in the pH range 7-9-3 and concluded that "the adsorption is a compli-*Clay-Organic Studies XXI. cated process in which oxidation of the organic molecule and cation exchange are involved.…”

Section: Introductionmentioning

confidence: 99%

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Adsorption and Oxidation of Benzidine and Aniline by Montmorillonite and Hectorite

Furukawa

1973

Clays and clay miner.

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Abstract--Quantitative measurements are made of the adsorption of benzidine and aniline from aqueous hydrochloride solutions by Na-, Li-, and Ca-montmorillonite and of the displaced inorganic cations. From these data, the ionic states of the adsorbed organic species are determined. Under conditions of controlled pH, the adsorption of benzidine increases as the pH increases, and involves mainly divalent species at pH < 3.2, and increasing proportions of monovalent and neutral species at pH > 3.2. With aniline, monovalent and neutral species are adsorbed, and hydrogen ions also appear to participate in the reactions.Color developments of benzidine and aniline complexes of montmorillonite and hectorite are considered qualitatively in relation to the adsorption data, to various experimental conditions including the nature of the inorganic exchangeable cations, the pH, and the presence or absence of oxygen in the system, and to relevant previous work. It is hypothesized that the blue color of the benzidine complex is due to semiquinone formation by oxidation on montmoriUonite by the clay itself, and on hectorite by dissolved oxygen or H202, and that the yellow color under acid conditions arises from reversible formation of quinoidal cations from semiquinones. The color developments of the aniline complex are due probably to oxidation of aniline by atmospheric oxygen.

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Section: Influence Of Controlled Ph On the Adsorption Of Benzidinementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Adsorption and Oxidation of Benzidine and Aniline by Montmorillonite and Hectorite

Furukawa

1973

Clays and clay miner.

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“…Studies of the interaction of benzidine with smectites to form a blue complex on the hydrated surfaces have been particularly numerous (see, for example, Lahav and Raziel, 1971). The oxidation mechanism evidently involves electron transfer from adsorbed benzidine to structural Fe 3+ in the octahedral layer of clays (Tennakoon et al, 1974a) to form the monovalent radical cation.…”

Section: Introductionmentioning

confidence: 99%

Surface Reactions of 3,3′,5,5′-Tetramethyl Benzidine on Hectorite

McBride

1985

Clays and clay miner.

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Abstract--The adsorption and oxidation of 3,3',5,5'-tetramethyl benzidine (TMB) on hectorite has been investigated using X-ray powder diffraction, ultraviolet-visible spectroscopy, electron spin resonance, and infrared spectroscopy. The molecule adsorbed by cation exchange at low adsorption levels and oxidized to the monomeric radical cation (yellow). At higher adsorption levels, intercalation of TMB occurred in amounts greater than the cation-exchange capacity of the hectorite, and the ~r-~r charge-transfer complex (blue) became much more evident. The TMB monomers appeared to lie fiat in the layer silicate interlayers, whereas the molecules in the charge-transfer complexes assumed a near-vertical orientation relative to the surface. The oxidation of adsorbed TMB was probably due to diffusion of O2 to the surface, because the structural Fe 3+ content of the hectorite was too low to facilitate a significant quantity of direct Fe 3+-TMB electron transfer.

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“…The pH of the solution was 6.7. The color reaction of benzidinemontmorillonite (Furukawa & Brindley, 1973;Lahav & Raziel, 1971;Theng, 1971) is pH sensitive: the benzidine-blue which is formed on the montmorillonite surface at slightly acid and alkaline conditions is changed into yellow upon adding acid. The yellow color is dominant at pH values below about 3 or so (Dodd & Ray, 1960).…”

Section: B E R N a L (1951) W A S T H E F I R S T To S U G G E S T T mentioning

confidence: 99%

Simultaneous existence of different environments in aqueous clay systems and its possible role in prebiotic synthesis

Lahav

1975

J Mol Evol

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The formation of packets of parallel oriented platelets and separating distances of several angstrom units in montmorillonite-water systems produces an intrinsic inhomogeneity with respect to the proton donating power of internal and external zones. Stable packets can be induced by both inorganic and organic molecules or ions, in suspensions or in drying-out systems. The coexistence of zones with different proton donating power was demonstrated by the pH-sensitive color reaction of benzidine, where stable packets of montmorillonite platelets were formed by the use of either paraquat or diquat. The close proximity of the two types of zones, which can be of the order of several angstroms, produces the conditions which were defined by Katchalsky as essential for the polymerization of amino acids. Since these enviromental conditions are quite common in nature, both at present and in prebiotic times, it is proposed that the inhomogeneity of clay-water systems with respect to proton donating power should be taken into account in both theoretical and experimental efforts to demonstrate the catalytic activity of clays in prebiotic synthesis.

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Interaction Between Montmorillonite and Benzidine in Aqueous Solutions I. Adsorption of Benzidine on Montmorillonite

Cited by 16 publications

References 12 publications

Adsorption and Oxidation of Benzidine and Aniline by Montmorillonite and Hectorite

Adsorption and Oxidation of Benzidine and Aniline by Montmorillonite and Hectorite

Surface Reactions of 3,3′,5,5′-Tetramethyl Benzidine on Hectorite

Simultaneous existence of different environments in aqueous clay systems and its possible role in prebiotic synthesis

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