Comparative study of ultrasound stimulation and conventional heating methods on the preparation of nanosized γ - Al2O3 / Abhijit Majhi in Industrial & engineering chemistry research, Vol. 49 N° 10 (Mai 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4710–4719 Titre : Comparative study of ultrasound stimulation and conventional heating methods on the preparation of nanosized γ - Al2O3 Type de document : texte imprimé Auteurs : Abhijit Majhi, Auteur ; G. Pugazhenthi, Auteur ; Anupam Shukla, Auteur Année de publication : 2010 Article en page(s) : pp. 4710–4719 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Nanosized Résumé : This work addresses the advantages of the ultrasound stimulation method over the conventional heating method for the preparation of nanosized γ-Al2O3. The γ-Al2O3 obtained by calcination of boehmite at 600 °C is derived from the inexpensive aluminum chloride salt by the precipitation route. Thermal evolution, phase transformation, surface area, and particle size distribution of the boehmite and γ-Al2O3 are characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared analysis (FT-IR), nitrogen adsorption−desorption isothermal data, and dynamic light scattering analysis (DLS). The γ-Al2O3 prepared by ultrasound stimulation has higher surface area (256 m2 g−1), bigger pore diameter (6.06 nm) and larger cumulative pore volume (0.388 cm3 g−1) than the conventional heating method (surface area, pore diameter, and pore volume of 219 m2 g−1, 5.61 nm, 0.307 cm3 g−1, respectively), which are even higher than the value reported in the literature for γ-Al2O3 synthesized at 100 °C for 24 h aging (pore diameter of 4.27 nm and pore volume of 0.26 cm3 g−1). The sonication applied during the aging of boehmite sol reduces the crystallite size (or particle size) and increases the porosity. The boehmite and γ-Al2O3 obtained by sonication have the highest porosity of 46% and 59%, respectively, without using any structure directing agent. The crystallite size calculated from XRD analysis using Scherrer’s equation is found to be 2.32 and 3.13 nm for boehmite and γ-Al2O3 obtained by ultrasound stimulation, respectively, which is due to the formation of microjets during sonication. The particle size analysis result reveals the formation of nanosized γ-Al2O3 particles by ultrasonication with a mean particle size of 51 nm. In conclusion, the boehmite and γ-Al2O3 prepared by ultrasound stimulation are better than the samples synthesized by the conventional method. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901857q [article] Comparative study of ultrasound stimulation and conventional heating methods on the preparation of nanosized γ - Al2O3 [texte imprimé] / Abhijit Majhi, Auteur ; G. Pugazhenthi, Auteur ; Anupam Shukla, Auteur . - 2010 . - pp. 4710–4719. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4710–4719 Mots-clés : Nanosized Résumé : This work addresses the advantages of the ultrasound stimulation method over the conventional heating method for the preparation of nanosized γ-Al2O3. The γ-Al2O3 obtained by calcination of boehmite at 600 °C is derived from the inexpensive aluminum chloride salt by the precipitation route. Thermal evolution, phase transformation, surface area, and particle size distribution of the boehmite and γ-Al2O3 are characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared analysis (FT-IR), nitrogen adsorption−desorption isothermal data, and dynamic light scattering analysis (DLS). The γ-Al2O3 prepared by ultrasound stimulation has higher surface area (256 m2 g−1), bigger pore diameter (6.06 nm) and larger cumulative pore volume (0.388 cm3 g−1) than the conventional heating method (surface area, pore diameter, and pore volume of 219 m2 g−1, 5.61 nm, 0.307 cm3 g−1, respectively), which are even higher than the value reported in the literature for γ-Al2O3 synthesized at 100 °C for 24 h aging (pore diameter of 4.27 nm and pore volume of 0.26 cm3 g−1). The sonication applied during the aging of boehmite sol reduces the crystallite size (or particle size) and increases the porosity. The boehmite and γ-Al2O3 obtained by sonication have the highest porosity of 46% and 59%, respectively, without using any structure directing agent. The crystallite size calculated from XRD analysis using Scherrer’s equation is found to be 2.32 and 3.13 nm for boehmite and γ-Al2O3 obtained by ultrasound stimulation, respectively, which is due to the formation of microjets during sonication. The particle size analysis result reveals the formation of nanosized γ-Al2O3 particles by ultrasonication with a mean particle size of 51 nm. In conclusion, the boehmite and γ-Al2O3 prepared by ultrasound stimulation are better than the samples synthesized by the conventional method. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901857q

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Modeling and simulation of stirred dead end ultrafiltration process using the aspen engineering suite / Sabuj Das in Industrial & engineering chemistry research, Vol. 48 N° 9 (Mai 2009)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4428–4439 Titre : Modeling and simulation of stirred dead end ultrafiltration process using the aspen engineering suite Type de document : texte imprimé Auteurs : Sabuj Das, Auteur ; Prabirkumar Saha, Auteur ; G. Pugazhenthi, Auteur Année de publication : 2009 Article en page(s) : pp. 4428–4439 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Pressure-driven membrane process Stirred cell Aspen engineering suite Résumé : Simulation of pressure-driven membrane process has been carried out considering two different types of solute (silica and dextran) and membrane (partially permeable and totally retentive) in a stirred cell using the Aspen Engineering Suite. One solute, silica, exerts negligible osmotic pressure but the other, dextran, offers adequate osmotic pressure. Silica is very susceptible to form a gel layer while dextran has no such tendency. Two types of membrane are considered for this work. One membrane completely separates solute from the solvent (totally retentive membrane) and the other does it partially (partially permeable membrane). The second type of membrane is regarded as highly compact granulated particle layer which has a different range of porosity. So the diffusivity within the membrane layer is referred to as hindered back diffusion. Osmotic pressure model and gel polarization model have been considered for batch and continuous mode operation. Silica suspension has been simulated with totally retentive membrane and dextran solution is simulated with partially retentive membrane in batch and continuous mode, respectively. The effect of applied pressure, stirring speed, and initial feed concentration on permeate flux, membrane surface concentration, permeate concentration, and true and observed rejection have been studied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801293d [article] Modeling and simulation of stirred dead end ultrafiltration process using the aspen engineering suite [texte imprimé] / Sabuj Das, Auteur ; Prabirkumar Saha, Auteur ; G. Pugazhenthi, Auteur . - 2009 . - pp. 4428–4439. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4428–4439 Mots-clés : Pressure-driven membrane process Stirred cell Aspen engineering suite Résumé : Simulation of pressure-driven membrane process has been carried out considering two different types of solute (silica and dextran) and membrane (partially permeable and totally retentive) in a stirred cell using the Aspen Engineering Suite. One solute, silica, exerts negligible osmotic pressure but the other, dextran, offers adequate osmotic pressure. Silica is very susceptible to form a gel layer while dextran has no such tendency. Two types of membrane are considered for this work. One membrane completely separates solute from the solvent (totally retentive membrane) and the other does it partially (partially permeable membrane). The second type of membrane is regarded as highly compact granulated particle layer which has a different range of porosity. So the diffusivity within the membrane layer is referred to as hindered back diffusion. Osmotic pressure model and gel polarization model have been considered for batch and continuous mode operation. Silica suspension has been simulated with totally retentive membrane and dextran solution is simulated with partially retentive membrane in batch and continuous mode, respectively. The effect of applied pressure, stirring speed, and initial feed concentration on permeate flux, membrane surface concentration, permeate concentration, and true and observed rejection have been studied. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801293d

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