Hydrolytic Polymerization in Boiled Chromic Solutions<sup>1</sup>

Laswick, John A.; Plane, Robert A.

doi:10.1021/ja01523a020

Cited by 77 publications

(33 citation statements)

References 2 publications

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“…Dimeric species of Cr in solution were thoroughly studied by Ardon and Plane (1959), Laswick and Plane (1959), and Thompson and Connick (1981). Two possible stoichiometric formulas--[HzO)sCrOCr(H20)9] +4 or [(H20)4Cr(OH)zCr(H20)4]+4--were established by Kolaczkowski and Plane (1964).…”

Section: Resultsmentioning

confidence: 99%

“…Two possible stoichiometric formulas--[HzO)sCrOCr(H20)9] +4 or [(H20)4Cr(OH)zCr(H20)4]+4--were established by Kolaczkowski and Plane (1964). The trimeric complex, Cr3(OH)4 + 5, was obtained by Laswick and Plane (1959) and Finholt et al (1981) by ion exchange. Stfinzi and Marty (1983) phadex SPC-25 gel, and they found in this way several new polymeric complexes (tetrameric, pentamer, and hexamer, although the last two complexes have not been studied in detail).…”

Section: Resultsmentioning

confidence: 99%

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Hydroxy-Chromium Smectite

Volzone¹,

Cesio²,

Sánchez³

et al. 1993

Clays and clay miner.

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Abstract--Hydroxy-chromium solutions were prepared from chromium nitrate solutions by adding NaOH with OH/Cr = 2.The solutions were treated at 20~ and 60~ The hydrolysis "times were from 1 to 100 days. Polymeric species in hydrolyzed chromium solutions were followed by visible absorption spectra within the range 325-800 nm and by pH measurement. OH-Cr-smectite with high d(001) spacing (2.07 nm) was obtained when hydroxy-chromium solution was prepared at 60~ and with 1-day hydrolysis. When this sample was heated up to 350~ the basal spacing collapsed at 1.8 nm.The samples were characterized by X-ray diffraction and N2 adsorption-desorption isotherms.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Hydroxy-Chromium Smectite

Volzone¹,

Cesio²,

Sánchez³

et al. 1993

Clays and clay miner.

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“…A solution (300 ml) containing the maximum amount of dimeric Cr(III) (designated 'dimer') was prepared by heating a solution containing 100 ml of each of 0.1 mole/liter Cr(NO3)3, 0.1 mole/liter NaOH, and distilled water to about 80~ for 40 rain. No at- tempt was made to estimate the concentrations of dimeric Cr(III) in these solutions, but data obtained by Laswick and Plane (1959) indicate that about 50% of the available Cr in the heated solution could have been polymeric. Five-gram samples of Na-montmorillonite were dispersed in 100 ml of each Cr solution and stirred periodically.…”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, it is known that these processes of hydrolysis and polymerization occur in aqueous solutions of chromium(III) ions in the absence of catalysts (Earley and Cannon, 1965). The polymerization in which [Cr2(HaO)s(OH)2] 4+ and [Cr3(H20)9(OH)4] 5+ are formed is slow at 25~ (Baes and Mesmer, 1976), but quite rapid at 100~ (Laswick and Plane, 1959;Earley and Cannon, 1965). Cr(III) aqueous chemistry may be summarized as follows: A solution containing 0.…”

Section: Introductionmentioning

confidence: 99%

Hydration States of Interlamellar Chromium Ions in Montmorillonite

Carr

1985

Clays and clay miner.

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Abstraet--Hydroxychromium montmorillonites were prepared from solutions containing chromium nitrate and varying amounts of NaOH. The reactant Cr ions were hydrolyzed and, in some experiments, were dimerized to a significant extent. The extent of polymerization in the product formed from a solution containing a maximum amount of [Cr2(H20)s(OH)2] a+ was compared with that in products obtained from solutions containing monomer, [Cr(H20)5OH] 2 § and lesser amounts of the dimer. Despite the uncertainty about the nature and amounts of product interlamellar species, the catalytic effect of the montmorillonite interlayer on the hydrolysis and polymerization of Cr(III) appears to be independent of the nature of the reactant species. The validity of this conclusion depends to a large extent on the reliability of water determination in the clay mineral species, which is estimated to be no better than 5%. The assumption that H20+ is 'combined' and H20-is 'free' water is shown to be partially true, thereby causing some uncertainty in the interpretations of interlayer compositions.

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“…Thus, to develop efficient strategies for the removal of chromium from the sludge, it is important to understand the chemical behavior of chromium(III) in alkaline solutions. However, most of the studies on chromium(III) have been conducted in acidic to neutral systems, [2][3][4][5][6][7][8][9][10][11][12][13] while few data exist for alkaline solutions. For example, information is available on the hydrolysis and oligomerization of chromium(III) in acidic to neutral solutions.…”

Section: Introductionmentioning

confidence: 99%

Oligomerization of chromium(iii) and its impact on the oxidation of chromium(iii) by hydrogen peroxide in alkaline solutions

Rao

Zhang

Friese

et al. 2002

J. Chem. Soc., Dalton Trans.

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Kinetic studies on the oxidation of separated/characterized chromium(III) oligomers by hydrogen peroxide indicate that the degree of oligomerization has a significant impact on the rate of oxidation in alkaline solutions. The oxidation rate constant decreases in the order: monomer > dimer > trimer > aged/unseparated chromium(III) solution where higher oligomers dominate. SummaryMonomeric, dimeric and trimeric chromium(III) species in solution were separated by ion exchange and characterized with UV/Vis absorption and Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS). The kinetics of the oxidation of the separated species by hydrogen peroxide in alkaline solutions was studied by conventional and stopped-flow UV/Vis absorption spectroscopy. Results indicate that the intensity of Cr-Cr scattering in the EXAFS spectra (d Cr-Cr ~ 2.99 Å), a measure of the degree of oligomerization, increases as the solution alkalinity is increased. As the oligomerization proceeds, the rate of oxidation by hydrogen peroxide in alkaline solutions decreases in the order: monomer > dimer > trimer > aged/unseparated alkaline chromium(III) solution where higher 1 oligomers dominate. The dominant redox pathway has an inverse order with respect to C NaOH . The data suggest that the rate-determining step involves the weakening of the bridging bonds in the oligomer and a concomitant release of one hydroxyl group from the chromium(III) moiety upon the attack by hydrogen peroxide.

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Hydrolytic Polymerization in Boiled Chromic Solutions¹

Cited by 77 publications

References 2 publications

Hydroxy-Chromium Smectite

Hydroxy-Chromium Smectite

Hydration States of Interlamellar Chromium Ions in Montmorillonite

Oligomerization of chromium(iii) and its impact on the oxidation of chromium(iii) by hydrogen peroxide in alkaline solutions

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Hydrolytic Polymerization in Boiled Chromic Solutions1

Cited by 77 publications

References 2 publications

Hydroxy-Chromium Smectite

Hydroxy-Chromium Smectite

Hydration States of Interlamellar Chromium Ions in Montmorillonite

Oligomerization of chromium(iii) and its impact on the oxidation of chromium(iii) by hydrogen peroxide in alkaline solutions

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Hydrolytic Polymerization in Boiled Chromic Solutions¹