Texture of chromia aerogels and structure of their nanocrystals

Abecassis-Wolfovich, M.; Rotter, H.; Landau, Miron V.; Korin, Eli; Эренбург, А. И.; Mogilyansky, D.; Garshtein, E.

doi:10.1016/s0167-2991(03)80373-7

Cited by 7 publications

(3 citation statements)

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“…Chromia (Cr 2 O 3 ), possess specific applied applications such as in high-temperature resistant materials [1], corrosion resistant materials [2], liquid crystal displays [3], green pigment [4], heterogeneous catalysts [5,6], coating materials [7,8], and so on. The intrinsic properties of inorganic materials are mainly determined by their composition, structure, crystallinity, size and morphology; great efforts have been devoted to the investigation of different Cr 2 O 3 materials synthesis [9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization and Antibacterial Activities of Chromium Oxide Nanoparticles Against Klebsiella Pneumoniae

Sangwan¹,

Kumar²

2017

Asian J Pharm Clin Res

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Objective: This paper consists of synthesis of chromium oxide (Cr 2 O 3 ) nanoparticles by sol-gel technique, their characterization and investigation of antibacterial activity of these nanoparticles against pathogenic bacteria by measuring zone of inhibition, colony forming units, and optical density (OD) on solid agar media as well as in liquid medium. Methods:The Cr 2 O 3 nanoparticles were synthesized by sol-gel technique using tetraethylorthosilicate as precursor. The synthesized Cr 2 O 3 nanoparticles were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and transmission electron microscopy (TEM) techniques. The antibacterial effect of these Cr 2 O 3 nanoparticles against Klebsiella pneumoniae was investigated both on the solid agar plates and in liquid medium supplemented with different concentrations of Cr 2 O 3 nanoparticles. The antibacterial activity of Cr 2 O 3 nanoparticles was also compared with the antibacterial activities of the standard antibiotics such as ampicillin, chloramphenicol, penicillin G, streptomycin, sulphatriad, and tetracycline which were taken in the form of hexa discs.Results: Average particle size of the Cr 2 O 3 nanoparticles was found to be 24.0 nm. It was observed that K. pneumoniae is resistant to the penicillin G and ampicillin, but Cr 2 O 3 nanoparticles show good antibacterial property. The minimum inhibitory concentration of Cr 2 O 3 for K. pneumoniae is 2.5 mg/ml. The bacterial growth was monitored by measuring zone of Inhibition, colony formation unit, and OD method. Conclusion:Sol-gel technique is a convenient and easy technique for the synthesis of metal nanoparticles. Nanosized Cr 2 O 3 particles showed an effective antibacterial activity against K. pneumoniae. Therefore, Cr 2 O 3 nanoparticles due to its low manufacturing cost and high effectiveness in antimicrobial properties may find wide applications in various industries to address safety issues.

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Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization and Antibacterial Activities of Chromium Oxide Nanoparticles Against Klebsiella Pneumoniae

Sangwan¹,

Kumar²

2017

Asian J Pharm Clin Res

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“…Special attention has been focused on the formation and properties of chromium oxyhydroxide (CrO(OH)) and chromia (Cr 2 O 3 ), which are important in specific applications such as in high‐temperature‐resistant materials,8, 9 liquid crystal displays,10, 11 catalysts12, 13 and so on. It is well known that the intrinsic properties of inorganic materials are mainly determined by their composition, structure, crystallinity, size and morphology; great efforts have been devoted to the investigation of the synthesis of different chromium oxide materials 14–16. CrO(OH) nanocrystals of 3–5 nm have been prepared by critical CO 2 extraction of the urea‐assisted wet chromia gel mixture,17 and smaller CrO(OH) crystals with size 1–2 nm were obtained in chromia aerogel as well 13.…”

Section: Introductionmentioning

confidence: 99%

Transition of chromium oxyhydroxide nanomaterials to chromium oxide: a hot‐stage Raman spectroscopic study

Yang

Martens

Frost

2010

J Raman Spectroscopy

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The transition of disc-like chromium hydroxide nanomaterials to chromium oxide nanomaterials has been studied by hot-stage Raman spectroscopy. The structure and morphology of α-CrO(OH) synthesised using hydrothermal treatment were confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The Raman spectrum of α-CrO(OH) is characterised by two intense bands at 823 and 630 cm −1 attributed to ν 1 Cr III -O symmetric stretching mode and the band at 1179 cm −1 attributed to Cr III -OH δ deformation modes. No bands are observed above 3000 cm −1 . The absence of characteristic OH stretching vibrations may be due to short hydrogen bonds in the α-CrO(OH) structure. Upon thermal treatment of α-CrO(OH), new Raman bands are observed at 599, 542, 513, 396, 344 and 304 cm −1 , which are attributed to Cr 2 O 3 . This hot-stage Raman study shows that the transition of α-CrO(OH) to Cr 2 O 3 occurs before 350 • C.

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“…Chromium based materials are receiving considerable attention for their numerous applications such as in green pigments, heterogeneous catalysis, coating materials for thermal protection, and wear resistance. This is due to their excellent corrosion resistance, high hardness and good temperaturestability [1,2]. However, the toxicity of chromium has been the main challenge hampering its potential applications.…”

Section: Introductionmentioning

confidence: 99%

Hexavalent chromium reduction by ZnO, SnO2 and ZnO-SnO2 synthesized using biosurfactants from extract of Solanum macrocarpon

Onwudiwe

Oyewo

Ogunjinmi

et al. 2021

Preprint

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In this study, ZnO, SnO2 and their composite (ZnO-SnO2) were synthesized by green route using aqueous extract of Solanum macrocarpon fruit and were used for the photo-reduction of hexavalent chromium. The synthetic route involved a two-step procedure, induced by temperature via calcination at 350 and 600 ºC. The composite was prepared by the treatment of a mixture of the precursor compounds to a temperature up to 800 ºC, and the extension of the temperature to 1000 ºC, resulted in the emergence of ZnO-SnO2-ZTO. The nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and UV–vis spectroscopy. The XRD studies of the binary oxides confirmed a hexagonal wurtzite structure for the ZnO and a cubic structure for the SnO2, without any change in the diffraction patterns or supplementary diffraction peaks. The morphology of the nanoparticles indicated fairly spherical shapes for the ZnO, that tend to agglomerate with increase in temperature. The SnO2 showed rectangular shapes at both temperatures of reaction, while the ZnO-SnO2 composite showed the presence of both morphologies of the component binary oxides. In the photo-enhanced degradation study, under ultra-violet light, the effect of pH (2–8), concentration of chromium(VI) (2–8 ppm), and photocatalyst dosage (25–150 mg/L) on the reduction of Cr(VI) to Cr(III) were investigated. The reduction showed higher efficiency in acidic environment than in the alkaline environment, and also with increase in photocatalyst dosage. The composite exhibited the highest photoreduction efficiency, above 90%, at the optimum condition of pH 2, 150 mg/L photocatalyst, 2 ppm chromium solution after 90 min. These low-cost and non-toxic metal oxide and their green synthesized composite have great potentials for Cr(VI) pollution clean-up from waste water.

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Texture of chromia aerogels and structure of their nanocrystals

Cited by 7 publications

References 2 publications

Synthesis, Characterization and Antibacterial Activities of Chromium Oxide Nanoparticles Against Klebsiella Pneumoniae

Synthesis, Characterization and Antibacterial Activities of Chromium Oxide Nanoparticles Against Klebsiella Pneumoniae

Transition of chromium oxyhydroxide nanomaterials to chromium oxide: a hot‐stage Raman spectroscopic study

Hexavalent chromium reduction by ZnO, SnO2 and ZnO-SnO2 synthesized using biosurfactants from extract of Solanum macrocarpon

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