Synthesis and characterize of trivalent chromium Cr(OH) 3 and Cr 2 O 3 microspheres

Xu, Haitao; Lou, Tianjun; Li, Yadong

doi:10.1016/j.inoche.2004.03.012

Cited by 40 publications

(17 citation statements)

References 20 publications

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“…No CAC was found in the treated COPRs, illustrating that Cr(VI) was effectively reduced. No Cr(OH)3 phase was identified in SD(12×), indicating that the reduction product of Cr(VI) by Na2S2O4 was amorphous, which agrees well with previous studies (Istok et al, 1999;Namgung et al, 2014;Rai et al, 2002;Su and Ludwig, 2005;Xu et al, 2004). The addition of Na3PO4, either through OSP or TSP, resulted in the formation of crystalline chromium phosphate hexahydrate (CrPO4·6H2O) which is more stable and insoluble than amorphous Cr(OH)3 (Gomm et al, 2007;Mustafa et al, 2005), leading to the lower TCLP Cr than observed for SD(12×).…”

Section: X-ray Diffraction Analysessupporting

confidence: 91%

Remediation of hexavalent chromium contamination in chromite ore processing residue by sodium dithionite and sodium phosphate addition and its mechanism

Cundy

Feng

et al. 2017

Journal of Environmental Management

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Large amounts of chromite ore processing residue (COPR) wastes have been deposited in many countries worldwide, generating significant contamination issues from the highly mobile and toxic hexavalent chromium species (Cr(VI)). In this study, sodium dithionite (Na2S2O4) was used to reduce Cr(VI) to Cr(III) in COPR containing high available Fe, and then sodium phosphate (Na3PO4) was utilized to further immobilize Cr(III), via a two-step procedure (TSP). Remediation and immobilization processes and mechanisms were systematically investigated using batch experiments, sequential extraction studies, X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). Results showed that Na2S2O4 effectively reduced Cr(VI) to Cr(III), catalyzed by Fe(III). The subsequent addition of Na3PO4 further immobilized Cr(III) by the formation of crystalline CrPO4·6H2O. However, addition of Na3PO4 simultaneo us ly with Na2S2O4 (via a one-step procedure, OSP) impeded Cr(VI) reduction due to the competitive reaction of Na3PO4 and Na2S2O4 with Fe(III). Thus, the remediatio n efficiency of the TSP was much higher than the corresponding OSP. Using an optimal dosage in the two-step procedure (Na2S2O4 at a dosage of 12× the stoichiome tr ic requirement for 15 days, and then Na3PO4 in a molar ratio (i.e. Na3PO4 : initial Cr(VI)) of 4:1 for another 15 days), the total dissolved Cr in the leachate determined via Toxicity Characteristic Leaching Procedure (TCLP Cr) testing of our samples was reduced to 3.8 mg/L (from an initial TCLP Cr of 112.2 mg/L, i.e. at >96% efficiency).

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Section: X-ray Diffraction Analysessupporting

confidence: 91%

Remediation of hexavalent chromium contamination in chromite ore processing residue by sodium dithionite and sodium phosphate addition and its mechanism

Cundy

Feng

et al. 2017

Journal of Environmental Management

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“…3. Given the similarities between these microspheres and the hydroxide microspheres deliberately synthesized in other systems [20][21][22], it is possible that the spherical particles formed here are amorphous europium hydroxide. This suggestion is supported by the experimental effect of reaction temperature and molar reactant ratio on the amount of microspheres formed.…”

Section: Article In Pressmentioning

confidence: 99%

Hydroxide carbonates and oxide carbonate hydrate of rare earths grown on glass via a hydrothermal route

Han

Ratinac

et al. 2004

Journal of Crystal Growth

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“…Chromium (III) oxide is used as green pigment,[] catalyst[] and for coating and wear resistance[] applications. Many synthetic routes for obtaining Cr 2 O 3 nanoparticles have been proposed such as hydrothermal,[] sol‐gel,[] forced hydrolysis,[] radiation,[] sonochemical[] and hydrolysis‐condensation. [] Depending on the synthesis method, as‐prepared Cr(III)‐oxide nanoparticles may or may not be crystalline in X‐ray diffraction (XRD) measurements.…”

Section: Introductionmentioning

confidence: 99%

“…[] Depending on the synthesis method, as‐prepared Cr(III)‐oxide nanoparticles may or may not be crystalline in X‐ray diffraction (XRD) measurements. [] In addition, their exact chemistry has been an issue of vivid debate in the scientific community. [] However, it is well known that after calcination at 400 °C[] or above,[] amorphous Cr(III)‐oxide nanoparticles are converted into crystalline α ‐Cr 2 O 3 .…”

Section: Introductionmentioning

confidence: 99%

A micro‐Raman spectroscopic study of Cr(OH)₃ and Cr₂O₃ nanoparticles obtained by the hydrothermal method

Gomes

Yaghini

Martinelli

et al. 2017

J Raman Spectroscopy

107

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Cr2O3 nanoparticles, widely used in the industry, can be obtained by calcination of the nanoparticles synthesized via the hydrothermal method. The chemical nature and the morphology of as‐prepared and calcined nanoparticles are investigated by scanning electron microscopy, X‐ray diffraction and Raman spectroscopy. Our results indicate that the as‐prepared nanoparticles mainly consist of amorphous and hydrated Cr(OH)3, with only minor amounts of Cr2O3. By contrast, and as already known before, calcined nanoparticles consist of Cr2O3. We also demonstrate the effect of inappropriately chosen experimental conditions, because the use of laser intensities above 0.7 mW during the Raman experiments causes a local heating and thus induces the transformation of Cr(OH)3 into Cr2O3. The correlation between the laser power and a local heating is further corroborated by thermogravimetric analyses, which show that upon increased temperature, Cr(OH)3 first dehydrates and then partially condensates to the intermediate CrO(OH) form, to finally attain the crystalline form of Cr2O3 at about 409 °C. Copyright © 2017 John Wiley & Sons, Ltd.

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Synthesis and characterize of trivalent chromium Cr(OH) 3 and Cr 2 O 3 microspheres

Cited by 40 publications

References 20 publications

Remediation of hexavalent chromium contamination in chromite ore processing residue by sodium dithionite and sodium phosphate addition and its mechanism

Remediation of hexavalent chromium contamination in chromite ore processing residue by sodium dithionite and sodium phosphate addition and its mechanism

Hydroxide carbonates and oxide carbonate hydrate of rare earths grown on glass via a hydrothermal route

A micro‐Raman spectroscopic study of Cr(OH)₃ and Cr₂O₃ nanoparticles obtained by the hydrothermal method

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Synthesis and characterize of trivalent chromium Cr(OH) 3 and Cr 2 O 3 microspheres

Cited by 40 publications

References 20 publications

Remediation of hexavalent chromium contamination in chromite ore processing residue by sodium dithionite and sodium phosphate addition and its mechanism

Remediation of hexavalent chromium contamination in chromite ore processing residue by sodium dithionite and sodium phosphate addition and its mechanism

Hydroxide carbonates and oxide carbonate hydrate of rare earths grown on glass via a hydrothermal route

A micro‐Raman spectroscopic study of Cr(OH)3 and Cr2O3 nanoparticles obtained by the hydrothermal method

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A micro‐Raman spectroscopic study of Cr(OH)₃ and Cr₂O₃ nanoparticles obtained by the hydrothermal method