Early stages of the hydrolysis of chromium(III) in aqueous solution. 4. The stability constants of the hydrolytic dimer, trimer, and tetramer at 25.degree.C and I = 1.0 M

Stuenzi, H.; Spiccia, Leone; Rotzinger, François P.; Marty, Werner

doi:10.1021/ic00300a015

Cited by 101 publications

(52 citation statements)

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“…That is the smectite retained all Cr species. The structures of the mono, dimer, trimer and tetramer species have the composition Cr +3, Cr2(OH)2 +4, Cr3(OH)4 +5, Cr4(OH)6 +5/+6, respectively (Stiinzi 1989). According to the species present in solution 1/60, it was possible to estimate the average meq Cr added per gram of sample.…”

Section: Plesmentioning

confidence: 99%

Hydroxy-Chromium Smectite: Influence of Cr Added

Volzone¹

1995

Clays and clay miner.

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Abstraet--OH-Cr smectites were prepared with different mmol Cr/g smectite: 0.5, 1.5, 3.5, 5, 10 and 20 by treatment with hydroxy-chromium solution prepared at 60"C and one day of hydrolysis with OH/Cr = 2. The samples were characterized by X-ray diffraction (XRD), differential thermal analyses (DTA) and N2 adsorption-desorption isotherms.The d(001) spacings of OH-Cr-smectite were different according to Cr added/g smectite. Larger d(001) spacings: 1.95, 2.05 and 2.07 nm were obtained with 5, 10 and 20 mmol Cr per gram of sample. DTA diagrams of smectite treated with OH-Cr solution showed exothermic peak at 420"C corresponding to Cr203 (confirmed by XRD). N2 adsorption-desorption isotherms ofsmectite treated with different amounts of Cr preserved the same slit-shaped pores than original sample, but with different micropore volume. This behavior was maintained until treatment temperature of 380"C. The specific area of smectite was increased from 36 to 175 m2/g after treatment with OH-Cr solution. The textural characteristics of OHCr smectite heated up to 420"C were changed. The specific area decreased and mesopore volume was produced. The different Cr added modified the structural and textural behavior.

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Section: Plesmentioning

confidence: 99%

Hydroxy-Chromium Smectite: Influence of Cr Added

Volzone¹

1995

Clays and clay miner.

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“…3). For kinetically inert metal centers, such as Cr, protonation-deprotonation reactions are rapid, while substitution involved in oligomer formation is slow (Stunzi et al 1989). Thus, the aging effect seems to be due to the formation of polymeric Cr(II1) species inert to oxidation (Baloga and Earley 1961).…”

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confidence: 99%

Chromium speciation in seawater: The probable role of hydrogen peroxide

Pettine

Millero

1990

Limnology & Oceanography

116

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“…The OH-Cr solution was prepared from 0.1 M chromium nitrate solution by the addition of 0.2 M NaOH (OH/Cr=2) at 60 °C and hydrolyzed for 1 day [14]. The OH-Cr solutions contained mainly trimeric species, Cr 3 (OH) 4 5+ , followed by tetra-, Cr 4 species [15]. OH-Cr-beidellite was obtained by slowly adding hydrolyzed OH-Cr-solution to beidellite (HB) water suspension (2% w/w).…”

Section: Methodsmentioning

confidence: 99%

“…This kind of peak depends on perfection of stacking of the layers and gross substitution [18,19]. The exothermic peak in the range of 355-410 °C is related to formation of Cr 2 O 3 in oxygen atmosphere [15]. A new endothermic peak at 1243 °C for beidellite-chromium in oxygen and two peaks for the same sample but in nitrogen atmosphere (1005 and 1248 °C), regarding to untreated beidellite, appeared and they were analyzed in the following section by using XRD analysis.…”

Section: Ohcr-beidellite Characterizationmentioning

confidence: 99%

“…This behavior is due to the Na + in interlayer cations was exchanged by OHCr cation specie. The 21.2 Å value is equivalent to a separate distance between layers of the 11.7 Å (21.2-9.5, 2:1 layer 9 ) 5+ in the prepared OH-Cr solution, and the height of the constituent octahedral of such species is 5.43 Å [15], the arrangement species in interlayer spacing can be in two horizontal sheets.…”

Section: Ohcr-beidellite Characterizationmentioning

confidence: 99%

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Structural changes of Cr-beidellite treated up to 1350 °C in oxygen or nitrogen atmospheres

Santos¹,

Cesio²,

Gauna³

et al. 2018

Cerâmica

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Beidellite clay mineral after intercalation of OH-Cr(III) species were thermally analyzed up to 1350 °C in oxygen and nitrogen atmospheres. OH-Cr-beidellite can be used as a pillared clay precursor for catalysis or as adsorbent applications. However, in this paper beidellite enriched in chromium were analyzed at different thermal treatments up to high temperature for evaluating structural changes for possible future ceramic applications. The structural changes were followed by thermal analysis and X-ray diffraction. The thermal treatment of OH-Cr-beidellite in oxygen and nitrogen atmospheres developed different mineralogical phases up to 1050 °C, but at higher temperatures, the same phases were developed in both atmosphere treatments. Eskolaite phase (Cr2O3) appeared in the sample after heating at 400 °C in oxygen atmosphere, whereas grimaldite (CrO-OH) in nitrogen atmosphere, maintaining the starting phases. At 1000 °C the raw clay minerals disappeared, as it is knew. At 1050 °C in nitrogen atmosphere, grimaldite was absent and eskolaite appeared. At 1350 °C in the samples calcined in both atmospheres, quartz, cristobalite and mullite as the main phases and in lower contents aluminum oxide and aluminum-chromium oxide [(Al,Cr)2O3] were present.

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Early stages of the hydrolysis of chromium(III) in aqueous solution. 4. The stability constants of the hydrolytic dimer, trimer, and tetramer at 25.degree.C and I = 1.0 M

Cited by 101 publications

References 0 publications

Hydroxy-Chromium Smectite: Influence of Cr Added

Hydroxy-Chromium Smectite: Influence of Cr Added

Chromium speciation in seawater: The probable role of hydrogen peroxide

Structural changes of Cr-beidellite treated up to 1350 °C in oxygen or nitrogen atmospheres

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