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Surface Modification and Planar Defects of Calcium Carbonates by Magnetic Water Treatment.

Liu CZ, Lin CH, Yeh MS, Chao YM, Shen P - Nanoscale Res Lett (2010)

Bottom Line: Calcite were found to form faceted nanoparticles having 3x (01̄14) commensurate superstructure and with well-developed {112̄0} and {101̄4} surfaces to exhibit preferred orientations.The (hkil)-specific coalescence of calcite and rapid lath growth of aragonite under the combined effects of Lorentz force and a precondensation event account for a beneficial larger particulate/colony size for the removal of the carbonate scale from the steel substrate.The coexisting magnetite particles have well-developed {011} surfaces regardless of MWT.

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ABSTRACT
Powdery calcium carbonates, predominantly calcite and aragonite, with planar defects and cation-anion mixed surfaces as deposited on low-carbon steel by magnetic water treatment (MWT) were characterized by X-ray diffraction, electron microscopy, and vibration spectroscopy. Calcite were found to form faceted nanoparticles having 3x (01̄14) commensurate superstructure and with well-developed {112̄0} and {101̄4} surfaces to exhibit preferred orientations. Aragonite occurred as laths having 3x (01̄1) commensurate superstructure and with well-developed (01̄1) surface extending along [100] direction up to micrometers in length. The (hkil)-specific coalescence of calcite and rapid lath growth of aragonite under the combined effects of Lorentz force and a precondensation event account for a beneficial larger particulate/colony size for the removal of the carbonate scale from the steel substrate. The coexisting magnetite particles have well-developed {011} surfaces regardless of MWT.

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a FTIR of OH-signified calcite (C), aragonite (A), and magnetite (M) of the same specimens as in Fig. 1, showing the OH− stretch at 3,400 cm−1 and characteristic absorption bands of the three phases as labeled and assigned in text. The corresponding Raman spectrum b shows the characteristic peaks with assigned vibration modes in text. There is considerable frequency change due to defects and partial disorder (cf. text)
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Figure 8: a FTIR of OH-signified calcite (C), aragonite (A), and magnetite (M) of the same specimens as in Fig. 1, showing the OH− stretch at 3,400 cm−1 and characteristic absorption bands of the three phases as labeled and assigned in text. The corresponding Raman spectrum b shows the characteristic peaks with assigned vibration modes in text. There is considerable frequency change due to defects and partial disorder (cf. text)

Mentions: The FTIR analysis indicated a significant OH-signature (~3,400 cm−1) for calcite, aragonite, and magnetite coexisting in the scale (Fig. 8a). The predominant calcite showed strong bands at 1,423 cm−1 for doubly degenerate asymmetric stretching, 875 cm−1 for out-of-plane bending, and 711 cm−1 for doubly degenerate planar bending based on previous assignments [[18]]. The shoulder on the low-frequency side of the 875 and 711 cm−1 band indicates a minor amount of aragonite that has characteristic doublet bands in such frequencies [[18]]. The broad band of magnetite at 595 cm−1 is significantly higher in wave number than that of natural minerals [[19]], possibly due to Fe3+/Fe2+ ratio change and defects. The bands at 2,923 and 2,852 cm−1 are due to EtOH used for IR sample preparation.


Surface Modification and Planar Defects of Calcium Carbonates by Magnetic Water Treatment.

Liu CZ, Lin CH, Yeh MS, Chao YM, Shen P - Nanoscale Res Lett (2010)

a FTIR of OH-signified calcite (C), aragonite (A), and magnetite (M) of the same specimens as in Fig. 1, showing the OH− stretch at 3,400 cm−1 and characteristic absorption bands of the three phases as labeled and assigned in text. The corresponding Raman spectrum b shows the characteristic peaks with assigned vibration modes in text. There is considerable frequency change due to defects and partial disorder (cf. text)
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Related In: Results  -  Collection

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Figure 8: a FTIR of OH-signified calcite (C), aragonite (A), and magnetite (M) of the same specimens as in Fig. 1, showing the OH− stretch at 3,400 cm−1 and characteristic absorption bands of the three phases as labeled and assigned in text. The corresponding Raman spectrum b shows the characteristic peaks with assigned vibration modes in text. There is considerable frequency change due to defects and partial disorder (cf. text)
Mentions: The FTIR analysis indicated a significant OH-signature (~3,400 cm−1) for calcite, aragonite, and magnetite coexisting in the scale (Fig. 8a). The predominant calcite showed strong bands at 1,423 cm−1 for doubly degenerate asymmetric stretching, 875 cm−1 for out-of-plane bending, and 711 cm−1 for doubly degenerate planar bending based on previous assignments [[18]]. The shoulder on the low-frequency side of the 875 and 711 cm−1 band indicates a minor amount of aragonite that has characteristic doublet bands in such frequencies [[18]]. The broad band of magnetite at 595 cm−1 is significantly higher in wave number than that of natural minerals [[19]], possibly due to Fe3+/Fe2+ ratio change and defects. The bands at 2,923 and 2,852 cm−1 are due to EtOH used for IR sample preparation.

Bottom Line: Calcite were found to form faceted nanoparticles having 3x (01̄14) commensurate superstructure and with well-developed {112̄0} and {101̄4} surfaces to exhibit preferred orientations.The (hkil)-specific coalescence of calcite and rapid lath growth of aragonite under the combined effects of Lorentz force and a precondensation event account for a beneficial larger particulate/colony size for the removal of the carbonate scale from the steel substrate.The coexisting magnetite particles have well-developed {011} surfaces regardless of MWT.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
Powdery calcium carbonates, predominantly calcite and aragonite, with planar defects and cation-anion mixed surfaces as deposited on low-carbon steel by magnetic water treatment (MWT) were characterized by X-ray diffraction, electron microscopy, and vibration spectroscopy. Calcite were found to form faceted nanoparticles having 3x (01̄14) commensurate superstructure and with well-developed {112̄0} and {101̄4} surfaces to exhibit preferred orientations. Aragonite occurred as laths having 3x (01̄1) commensurate superstructure and with well-developed (01̄1) surface extending along [100] direction up to micrometers in length. The (hkil)-specific coalescence of calcite and rapid lath growth of aragonite under the combined effects of Lorentz force and a precondensation event account for a beneficial larger particulate/colony size for the removal of the carbonate scale from the steel substrate. The coexisting magnetite particles have well-developed {011} surfaces regardless of MWT.

No MeSH data available.


Related in: MedlinePlus