Hydroxy-Chromium Smectite

Volzone, Cristina; Cesio, Ana María; Sánchez, Rosa M. Torres; Pereira, Emmanuel Moreira

doi:10.1346/ccmn.1993.0410608

Cited by 31 publications

(16 citation statements)

References 20 publications

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“…The smectitic material (E) was supplied by Georgia Kaolin, Co. and was characterized in previous work (Volzone et al 1993). It corresponds to dioctahedral smectite with impurities of quartz and cristobalite in low proportions.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 2 shows the d(001) spacings of OH-Cr-smectite treated with 1/60 solutions according to different added mmol Cr/g of smectite. The mother liquid (1/ 60) contained abundant trimeric species and tetra-, mono-, and dimer (Volzone et al 1993). Small amount of Cr added did not produce higher spacings and it was possible that the amount of suitable species present in solution were not sufficient.…”

Section: Methodsmentioning

confidence: 99%

“…Rengasamy and Oades (1978), Brindley and Yamanaka (1979), Vaughan and Lussier (1980), Carr (1985), Pinnavaia et al (1988), Vaughan (1988), Tzou and Pinnavaia (1988), Drljaca et al (1992), Volzone et al (1993) wrote papers referred to OH-Cr-clay study. Species present in hydrolyzed chromium solution on preparation of OH-Cr smectite were observed by Drljaca et a11992, Volzone et al 1993, but there are no references about amount of Cr added to smectite to obtain this one good textural and structural characteristic.…”

Section: Introductionmentioning

confidence: 99%

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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: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Hydroxy-Chromium Smectite: Influence of Cr Added

Volzone¹

1995

Clays and clay miner.

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“…Then, the beidellite was transformed into beidellite-Na and named HB in this study. 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].…”

Section: Methodsmentioning

confidence: 99%

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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“…The smectite sample used in the study was supplied by Georgia Kaolin Co. and was characterized in a previous work (Volzone et al 1993). The smectite present was mainly montmorillonitic in nature.…”

Section: Differentmentioning

confidence: 99%