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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.

No MeSH data available.


a Lattice image, b and c 2-D forward and inverse Fourier transform, respectively, of the square region in (a) showing well-developed () and {} surfaces of the calcite nanocrystals. Note 1-D commensurate superstructure diffraction (denoted as S) with 3 times () d-spacing in (c). The scale sample was taken from the steel pipe subjected to MWT under 100 G at pipe center, 0.1 s/cycle, and with an electric ground to the Earth
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Figure 7: a Lattice image, b and c 2-D forward and inverse Fourier transform, respectively, of the square region in (a) showing well-developed () and {} surfaces of the calcite nanocrystals. Note 1-D commensurate superstructure diffraction (denoted as S) with 3 times () d-spacing in (c). The scale sample was taken from the steel pipe subjected to MWT under 100 G at pipe center, 0.1 s/cycle, and with an electric ground to the Earth

Mentions: The calcite nanoparticles with negligible Fe2+ and Fe3+ impurities, as indicated by the same EDX spectrum (not shown) as that of aragonite, were typically agglomerated in a close packed manner and tended to assemble by the {} and {} surfaces with preferred orientations to form elongate particulate up to microns in size (Fig. 6), which showed birefringence under optical polarized microscope (not shown). Lattice image (Fig. 7a) revealed further details of the individual calcite nanoparticles with well-developed () and {} surfaces both being edge on when viewed in [] zone axis as indicated by 2-D forward and inverse Fourier transform in Fig. 7b and 7c, respectively. This accounts for {}- and {}-specific coalescence of such shaped calcite nanoparticles into particulates with {} and {} preferred orientations as manifested by XRD and SAED results. The calcite nanocrystal also showed 1-D commensurate superstructure with 3 times that of the () d-spacing (Fig. 7c). TEM observations of the scale formed without an applied magnetic field (not shown) indicated that the calcite and aragonite nanoparticles have poorly developed {hkil}-specific surfaces and are immune from commensurate superstructures [[17]].


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 Lattice image, b and c 2-D forward and inverse Fourier transform, respectively, of the square region in (a) showing well-developed () and {} surfaces of the calcite nanocrystals. Note 1-D commensurate superstructure diffraction (denoted as S) with 3 times () d-spacing in (c). The scale sample was taken from the steel pipe subjected to MWT under 100 G at pipe center, 0.1 s/cycle, and with an electric ground to the Earth
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Figure 7: a Lattice image, b and c 2-D forward and inverse Fourier transform, respectively, of the square region in (a) showing well-developed () and {} surfaces of the calcite nanocrystals. Note 1-D commensurate superstructure diffraction (denoted as S) with 3 times () d-spacing in (c). The scale sample was taken from the steel pipe subjected to MWT under 100 G at pipe center, 0.1 s/cycle, and with an electric ground to the Earth
Mentions: The calcite nanoparticles with negligible Fe2+ and Fe3+ impurities, as indicated by the same EDX spectrum (not shown) as that of aragonite, were typically agglomerated in a close packed manner and tended to assemble by the {} and {} surfaces with preferred orientations to form elongate particulate up to microns in size (Fig. 6), which showed birefringence under optical polarized microscope (not shown). Lattice image (Fig. 7a) revealed further details of the individual calcite nanoparticles with well-developed () and {} surfaces both being edge on when viewed in [] zone axis as indicated by 2-D forward and inverse Fourier transform in Fig. 7b and 7c, respectively. This accounts for {}- and {}-specific coalescence of such shaped calcite nanoparticles into particulates with {} and {} preferred orientations as manifested by XRD and SAED results. The calcite nanocrystal also showed 1-D commensurate superstructure with 3 times that of the () d-spacing (Fig. 7c). TEM observations of the scale formed without an applied magnetic field (not shown) indicated that the calcite and aragonite nanoparticles have poorly developed {hkil}-specific surfaces and are immune from commensurate superstructures [[17]].

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.