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Preparation and characterization of calcium stearate powders and films prepared by precipitation and langmuir−blodgett techniques / Gonen, Mehmet in Industrial & engineering chemistry research, Vol. 49 N° 4 (Fevrier 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1732–1736 Titre : Preparation and characterization of calcium stearate powders and films prepared by precipitation and langmuir−blodgett techniques Type de document : texte imprimé Auteurs : Gonen, Mehmet, Auteur ; Ozturk, Serdar, Auteur ; Balkose, Devrim, Auteur Année de publication : 2010 Article en page(s) : pp 1732–1736 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Calcium  stearate  Langmuir  blodgett  techniques. Résumé : The preparation of calcium stearate (CaSt2) using precipitation and Langmuir−Blodgett techniques was investigated in this study. While sodium stearate and calcium chloride were used in the precipitation process, calcium stearate nanofilms were produced from stearic acid and calcium chloride in sodium borate buffer with the Langmuir−Blodgett technique. Fourier transform infrared (FTIR) spectroscopy indicated carboxylate bands at 1577 and 1543 cm−1 in equal intensity in the powder form, but the films had a higher intensity 1577 cm−1 band than the 1543 cm−1 band. This showed the calcium ions associated with the COO− ions in the monodendate and bidendate structures in powders, and it was mainly in the bidendate structure in films. While characteristic peaks of CaSt2 at 2θ values of 6.40° and 19.58° were obtained in the X-ray diffraction (XRD) pattern of the dried powdered product, no sharp peaks were present in the 13 layer CaSt2 film. From scanning electron microscopy (SEM) micrographs, it was seen that calcium stearate powder had lamellar structure and the average particle size was 600 nm. The AFM picture of the CaSt2 film indicated the surface was not smooth with a peak to valley distance of 6 nm. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901437d [article] Preparation and characterization of calcium stearate powders and films prepared by precipitation and langmuir−blodgett techniques [texte imprimé] / Gonen, Mehmet, Auteur ; Ozturk, Serdar, Auteur ; Balkose, Devrim, Auteur . - 2010 . - pp 1732–1736. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 4 (Fevrier 2010) . - pp 1732–1736 Mots-clés : Calcium  stearate  Langmuir  blodgett  techniques. Résumé : The preparation of calcium stearate (CaSt2) using precipitation and Langmuir−Blodgett techniques was investigated in this study. While sodium stearate and calcium chloride were used in the precipitation process, calcium stearate nanofilms were produced from stearic acid and calcium chloride in sodium borate buffer with the Langmuir−Blodgett technique. Fourier transform infrared (FTIR) spectroscopy indicated carboxylate bands at 1577 and 1543 cm−1 in equal intensity in the powder form, but the films had a higher intensity 1577 cm−1 band than the 1543 cm−1 band. This showed the calcium ions associated with the COO− ions in the monodendate and bidendate structures in powders, and it was mainly in the bidendate structure in films. While characteristic peaks of CaSt2 at 2θ values of 6.40° and 19.58° were obtained in the X-ray diffraction (XRD) pattern of the dried powdered product, no sharp peaks were present in the 13 layer CaSt2 film. From scanning electron microscopy (SEM) micrographs, it was seen that calcium stearate powder had lamellar structure and the average particle size was 600 nm. The AFM picture of the CaSt2 film indicated the surface was not smooth with a peak to valley distance of 6 nm. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901437d

Supercritical carbon dioxide drying of methanol-zinc borate mixtures / Gonen, Mehmet in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6869–6876 Titre : Supercritical carbon dioxide drying of methanol-zinc borate mixtures Type de document : texte imprimé Auteurs : Gonen, Mehmet, Auteur ; Balkose, Devrim, Auteur ; Gupta, Ram B., Auteur Année de publication : 2009 Article en page(s) : pp. 6869–6876 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon  dioxide  drying  Methanol-wetted  zinc  borates  X-ray  powder  diffraction  Thermo  gravimetric  analysis  Fourier  transform  infrared  spectroscopy  Elemental  analysis  Scanning  electron  microscopy Résumé : Supercritical carbon dioxide (CO2) drying of zinc borate species was investigated to evaluate possible chemical alterations in the product during the drying. Methanol-wetted zinc borates produced either from borax decahydrate and zinc nitrate hexahydrate (2ZnO·3B2O3·7H2O) or from zinc oxide and boric acid (2ZnO·3B2O3·3H2O) were dried by both conventional and supercritical carbon dioxide drying methods. Zinc borate samples dried by both techniques were characterized using analytical titration, X-ray powder diffraction (XRD), thermo gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and scanning electron microscopy (SEM). It was found that while zinc borate obtained from zinc oxide and boric acid did not have any chemical interaction with CO2, carbonates were formed on the surface of zinc borate obtained from borax decahydrate and zinc nitrate hexahydrate. The main factor for the carbonate formation during supercritical CO2 drying is anticipated as the structural differences of zinc borate species. CO2 is a nonpolar solvent, and it does not usually react with polar substances unless water is present in the medium. While 2ZnO·3B2O3·3H2O had three bound OH groups, 2ZnO·3B2O3·7H2O had five bound OH groups and one mole of water of crystallization. It is proposed that the water of crystallization reacts with CO2 forming carbonic acid. Then, carbonic acid, which is stronger than boric acid, substitutes borate ions from their zinc salts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003046 [article] Supercritical carbon dioxide drying of methanol-zinc borate mixtures [texte imprimé] / Gonen, Mehmet, Auteur ; Balkose, Devrim, Auteur ; Gupta, Ram B., Auteur . - 2009 . - pp. 6869–6876. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6869–6876 Mots-clés : Carbon  dioxide  drying  Methanol-wetted  zinc  borates  X-ray  powder  diffraction  Thermo  gravimetric  analysis  Fourier  transform  infrared  spectroscopy  Elemental  analysis  Scanning  electron  microscopy Résumé : Supercritical carbon dioxide (CO2) drying of zinc borate species was investigated to evaluate possible chemical alterations in the product during the drying. Methanol-wetted zinc borates produced either from borax decahydrate and zinc nitrate hexahydrate (2ZnO·3B2O3·7H2O) or from zinc oxide and boric acid (2ZnO·3B2O3·3H2O) were dried by both conventional and supercritical carbon dioxide drying methods. Zinc borate samples dried by both techniques were characterized using analytical titration, X-ray powder diffraction (XRD), thermo gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, elemental analysis, and scanning electron microscopy (SEM). It was found that while zinc borate obtained from zinc oxide and boric acid did not have any chemical interaction with CO2, carbonates were formed on the surface of zinc borate obtained from borax decahydrate and zinc nitrate hexahydrate. The main factor for the carbonate formation during supercritical CO2 drying is anticipated as the structural differences of zinc borate species. CO2 is a nonpolar solvent, and it does not usually react with polar substances unless water is present in the medium. While 2ZnO·3B2O3·3H2O had three bound OH groups, 2ZnO·3B2O3·7H2O had five bound OH groups and one mole of water of crystallization. It is proposed that the water of crystallization reacts with CO2 forming carbonic acid. Then, carbonic acid, which is stronger than boric acid, substitutes borate ions from their zinc salts. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9003046