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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]  in Industrial & 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

Negative rejection of NaCl in ultrafiltration of aqueous solution of NaCl and KCl using sodalite octahydrate zeolite − clay charged ultrafiltration membrane / Fasil Qayoom Mir in Industrial & engineering chemistry research, Vol. 49 N° 14 (Juillet 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp. 6539–6546 Titre : Negative rejection of NaCl in ultrafiltration of aqueous solution of NaCl and KCl using sodalite octahydrate zeolite − clay charged ultrafiltration membrane Type de document : texte imprimé Auteurs : Fasil Qayoom Mir, Auteur ; Anupam Shukla, Auteur Année de publication : 2010 Article en page(s) : pp. 6539–6546 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Aqueous  solution  Zéolithe Résumé : Permeation of mixed salt solution through charged membrane is a complex process, and depending upon electrostatic interaction among different types of ions and wall charges, complex separation behaviors such as negative rejection of a salt in the mixture have been observed for such systems. Negative rejection of a salt in an aqueous mixture of salts has been observed for nanofiltration membranes that have very small pores (pore diameter 1 nm). We report in this work studies on separation of mixed salt solutions of NaCl and KCl using a charge ultrafiltration membrane of large pore size (pore diameter 15−92 nm) whose preparation is described elsewhere [Workneh, S.; Shukla, A. J. Membr. Sci. 2008, 309, 189]. At a low total concentration of electrolytes in the feed (0.01 M), when the effective exclusion of co-ions occurs inside the membrane, negative rejection of NaCl is obtained. It is found that irrespective of the composition of the salt mixture used in this work, the magnitude of negative observed rejection increases with pressure initially but beyond a certain pressure its magnitude decreases by a small amount. It is also found that as the NaCl composition is increased the magnitude of negative observed rejection first increases but beyond a value of 60% NaCl it decreases for all the pressure differences used in this work. Simulated values of the intrinsic rejection coefficient, however, are found to increase monotonically with pressure, indicating that the maximum in magnitude of observed negative rejection is due to concentration polarization. With variation in feed composition the intrinsic rejection shows a trend similar to the observed rejection. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901775v [article] Negative rejection of NaCl in ultrafiltration of aqueous solution of NaCl and KCl using sodalite octahydrate zeolite − clay charged ultrafiltration membrane [texte imprimé] / Fasil Qayoom Mir, Auteur ; Anupam Shukla, Auteur . - 2010 . - pp. 6539–6546. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 14 (Juillet 2010) . - pp. 6539–6546 Mots-clés : Aqueous  solution  Zéolithe Résumé : Permeation of mixed salt solution through charged membrane is a complex process, and depending upon electrostatic interaction among different types of ions and wall charges, complex separation behaviors such as negative rejection of a salt in the mixture have been observed for such systems. Negative rejection of a salt in an aqueous mixture of salts has been observed for nanofiltration membranes that have very small pores (pore diameter 1 nm). We report in this work studies on separation of mixed salt solutions of NaCl and KCl using a charge ultrafiltration membrane of large pore size (pore diameter 15−92 nm) whose preparation is described elsewhere [Workneh, S.; Shukla, A. J. Membr. Sci. 2008, 309, 189]. At a low total concentration of electrolytes in the feed (0.01 M), when the effective exclusion of co-ions occurs inside the membrane, negative rejection of NaCl is obtained. It is found that irrespective of the composition of the salt mixture used in this work, the magnitude of negative observed rejection increases with pressure initially but beyond a certain pressure its magnitude decreases by a small amount. It is also found that as the NaCl composition is increased the magnitude of negative observed rejection first increases but beyond a value of 60% NaCl it decreases for all the pressure differences used in this work. Simulated values of the intrinsic rejection coefficient, however, are found to increase monotonically with pressure, indicating that the maximum in magnitude of observed negative rejection is due to concentration polarization. With variation in feed composition the intrinsic rejection shows a trend similar to the observed rejection. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901775v