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Mechanistic assessment of microalgal lipid extraction / Amrita Ranjan in Industrial & engineering chemistry research, Vol. 49 N° 6 (Mars 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2979–2985 Titre : Mechanistic assessment of microalgal lipid extraction Type de document : texte imprimé Auteurs : Amrita Ranjan, Auteur ; Chetna Patil, Auteur ; Vijayanand S. Moholkar, Auteur Année de publication : 2010 Article en page(s) : pp. 2979–2985 Note générale : Industrial Chemistry Langues : Anglais (eng) Mots-clés : Mechanistic--Microalgal--Lipid--Extraction Résumé : In this paper, we have attempted to make a comparative assessment of the three techniques for extraction of lipids from microalgal biomass, viz. Soxhlet extraction, the Bligh and Dyer method, and sonication. The approach is mechanistic in the sense that we have tried to determine the physical mechanism of extraction of lipids (cell disruption or diffusion across a cell wall) from microalgae using microscopic analysis of extracted biomass. We have also assessed the relative influence of the solvent (or extractant) selectivity and the intensity of convection in the medium on the overall lipid yield. None of the techniques used produced complete disruption of the cells, not even sonication. Thus, the prominent mechanism of lipid extraction was diffusion across a cell wall. Moreover, the selectivity of the solvent was found to be the most dominating factor in overall lipid extraction by diffusion than the intensity of bulk convection in the medium. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9016557 [article] Mechanistic assessment of microalgal lipid extraction [texte imprimé] / Amrita Ranjan, Auteur ; Chetna Patil, Auteur ; Vijayanand S. Moholkar, Auteur . - 2010 . - pp. 2979–2985. Industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2979–2985 Mots-clés : Mechanistic--Microalgal--Lipid--Extraction Résumé : In this paper, we have attempted to make a comparative assessment of the three techniques for extraction of lipids from microalgal biomass, viz. Soxhlet extraction, the Bligh and Dyer method, and sonication. The approach is mechanistic in the sense that we have tried to determine the physical mechanism of extraction of lipids (cell disruption or diffusion across a cell wall) from microalgae using microscopic analysis of extracted biomass. We have also assessed the relative influence of the solvent (or extractant) selectivity and the intensity of convection in the medium on the overall lipid yield. None of the techniques used produced complete disruption of the cells, not even sonication. Thus, the prominent mechanism of lipid extraction was diffusion across a cell wall. Moreover, the selectivity of the solvent was found to be the most dominating factor in overall lipid extraction by diffusion than the intensity of bulk convection in the medium. Note de contenu : Bibiogr. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9016557

Mechanistic features of ultrasound - assisted oxidative desulfurization of liquid fuels / Manohar Kumar Bolla in Industrial & engineering chemistry research, Vol. 51 N° 29 (Juillet 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 29 (Juillet 2012) . - pp. 9705–9712 Titre : Mechanistic features of ultrasound - assisted oxidative desulfurization of liquid fuels Type de document : texte imprimé Auteurs : Manohar Kumar Bolla, Auteur ; Hanif A. Choudhury, Auteur ; Vijayanand S. Moholkar, Auteur Année de publication : 2012 Article en page(s) : pp. 9705–9712 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Ultrasound  Oxidative  Liquid  fuels Résumé : A new technology for the removal of sulfur compounds from liquid fuels is oxidative desulfurization. Although several studies have reported the enhancement effect of ultrasound irradiation on oxidative desulfurization, the exact mechanism underlying this enhancement is not known yet. In this study, we have addressed this issue with dual approach of coupling experiments with mathematical model for cavitation. Results of this study have given interesting revelation of interaction between mechanism of ultrasound, cavitation, and oxidation system. Isolation of cavitation phenomenon helps to increase the extent of oxidation. This effect is attributed to formation of hydrogen and carbon monoxide during transient collapse of cavitation bubbles due to thermal dissociation of hexane vapor entrapped in the bubble, which hamper the action of O species generated from the oxidation system. Transient cavitation itself does not give rise to radical formation, because of rather low temperature peaks reached during collapse. Therefore, cavitation does not enhance the oxidation process, but in fact, has an adverse effect on it. Current study has established that the beneficial effect of ultrasound on oxidative desulfurization system is merely of a physical nature (i.e., emulsification due to intense micromixing), with no involvement of a sonochemical effect. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300807a [article] Mechanistic features of ultrasound - assisted oxidative desulfurization of liquid fuels [texte imprimé] / Manohar Kumar Bolla, Auteur ; Hanif A. Choudhury, Auteur ; Vijayanand S. Moholkar, Auteur . - 2012 . - pp. 9705–9712. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 29 (Juillet 2012) . - pp. 9705–9712 Mots-clés : Ultrasound  Oxidative  Liquid  fuels Résumé : A new technology for the removal of sulfur compounds from liquid fuels is oxidative desulfurization. Although several studies have reported the enhancement effect of ultrasound irradiation on oxidative desulfurization, the exact mechanism underlying this enhancement is not known yet. In this study, we have addressed this issue with dual approach of coupling experiments with mathematical model for cavitation. Results of this study have given interesting revelation of interaction between mechanism of ultrasound, cavitation, and oxidation system. Isolation of cavitation phenomenon helps to increase the extent of oxidation. This effect is attributed to formation of hydrogen and carbon monoxide during transient collapse of cavitation bubbles due to thermal dissociation of hexane vapor entrapped in the bubble, which hamper the action of O species generated from the oxidation system. Transient cavitation itself does not give rise to radical formation, because of rather low temperature peaks reached during collapse. Therefore, cavitation does not enhance the oxidation process, but in fact, has an adverse effect on it. Current study has established that the beneficial effect of ultrasound on oxidative desulfurization system is merely of a physical nature (i.e., emulsification due to intense micromixing), with no involvement of a sonochemical effect. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie300807a

Mechanistic investigations on sonophotocatalytic degradation of textile dyes with surface active solutes / Chilukoti Balaji in Industrial & engineering chemistry research, Vol. 50 N° 20 (Octobre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 20 (Octobre 2011) . - pp. 11485–11494 Titre : Mechanistic investigations on sonophotocatalytic degradation of textile dyes with surface active solutes Type de document : texte imprimé Auteurs : Chilukoti Balaji, Auteur ; Vijayanand S. Moholkar, Auteur ; Aniruddha B. Pandit, Auteur Année de publication : 2011 Article en page(s) : pp. 11485–11494 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Sonophotocatalytic Résumé : In recent years, two advanced oxidation processes, namely, photocatalysis and sonolysis have been extensively investigated for the degradation of recalcitrant organic pollutants. Simultaneous application of these two techniques, known as sonophotocatalysis has been found to give synergistic enhancement in degradation under specific experimental conditions. The present study attempts to establish the physical mechanism of sonophotocatalytic process by finding the synergy between two techniques that gives enhancement in degradation. Transient collapse of cavitation bubbles gives rise to light emission (known as sonoluminescence), which could provide activation of the photocatalyst. To test this hypothesis, we have conducted experiments on the basis of known effects of surface active solutes on sonoluminescence. Three different textile dyes have been chosen as model pollutants. Experiments have been conducted in the presence of three different surface active solutes, namely, SDS, 2-propanol, and 1-butanol. The rate of degradation reduces drastically with the addition of surface active solutes. The reduction in the degradation process ranges from 5-fold (for Acid Red B) to 20% (for Direct Blue 6) for SDS, while for alcohols much higher ( 10-fold) reduction is seen for all three dyes. It is revealed that the interaction between photocatalyst and sonolysis is merely of physical nature. The sonoluminescence light from cavitation bubbles is not able to activate the photocatalyst. The role of TiO2 is revealed to be only that of an adsorbent for the dyes. The degradation is caused mostly due to the radicals generated by the cavitation bubble, with negligible role of the radical generation from photocatalyst. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201127v [article] Mechanistic investigations on sonophotocatalytic degradation of textile dyes with surface active solutes [texte imprimé] / Chilukoti Balaji, Auteur ; Vijayanand S. Moholkar, Auteur ; Aniruddha B. Pandit, Auteur . - 2011 . - pp. 11485–11494. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 20 (Octobre 2011) . - pp. 11485–11494 Mots-clés : Sonophotocatalytic Résumé : In recent years, two advanced oxidation processes, namely, photocatalysis and sonolysis have been extensively investigated for the degradation of recalcitrant organic pollutants. Simultaneous application of these two techniques, known as sonophotocatalysis has been found to give synergistic enhancement in degradation under specific experimental conditions. The present study attempts to establish the physical mechanism of sonophotocatalytic process by finding the synergy between two techniques that gives enhancement in degradation. Transient collapse of cavitation bubbles gives rise to light emission (known as sonoluminescence), which could provide activation of the photocatalyst. To test this hypothesis, we have conducted experiments on the basis of known effects of surface active solutes on sonoluminescence. Three different textile dyes have been chosen as model pollutants. Experiments have been conducted in the presence of three different surface active solutes, namely, SDS, 2-propanol, and 1-butanol. The rate of degradation reduces drastically with the addition of surface active solutes. The reduction in the degradation process ranges from 5-fold (for Acid Red B) to 20% (for Direct Blue 6) for SDS, while for alcohols much higher ( 10-fold) reduction is seen for all three dyes. It is revealed that the interaction between photocatalyst and sonolysis is merely of physical nature. The sonoluminescence light from cavitation bubbles is not able to activate the photocatalyst. The role of TiO2 is revealed to be only that of an adsorbent for the dyes. The degradation is caused mostly due to the radicals generated by the cavitation bubble, with negligible role of the radical generation from photocatalyst. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201127v

Mechanistic studies in ultrasound-assisted adsorption for removal of aromatic pollutants / Venkata Rao Midathana in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7368–7377 Titre : Mechanistic studies in ultrasound-assisted adsorption for removal of aromatic pollutants Type de document : texte imprimé Auteurs : Venkata Rao Midathana, Auteur ; Vijayanand S. Moholkar, Auteur Année de publication : 2009 Article en page(s) : pp. 7368–7377 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Organic  pollutants  Ultrasound  Adsorption Résumé : In this paper we try to discern the physical mechanism of enhancement of adsorption of organic pollutants with application of ultrasound. An attempt is made to discriminate between the contribution made by various physical effects of ultrasound and cavitation, viz., microstreaming, microturbulence, and acoustic (or shock) waves, which could generate convection in the medium and enhance the process of adsorption. A dual approach of coupling experimental results to the simulations of a bubble dynamics model has been adopted. Adsorption of three aromatic pollutants (viz., nitrobenzene, phenol, and p-nitrophenol) onto activated carbon has been chosen as a model process. Correlation of the experimental and simulation results reveals that the extent of adsorption in the presence of ultrasound shows an optimum with the intensity of convection generated in the medium by the cavitation bubbles. The microturbulence generated by cavitation bubbles makes a useful contribution to the enhancement of adsorption. This is attributed to the continuous nature of microturbulence with moderate liquid velocities. On the other hand, acoustic waves emitted by the cavitation bubbles render an adverse effect on the process. This is attributed to the discrete nature and high pressure amplitude of the waves, which create excessively high convection in the medium, causing desorption of the pollutant. The chemical nature of the pollutant is also found to influence the enhancement effect of ultrasound. For hydrophobic pollutants, the ultrasonic enhancement is more pronounced than for hydrophilic pollutants under otherwise similar conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900049e [article] Mechanistic studies in ultrasound-assisted adsorption for removal of aromatic pollutants [texte imprimé] / Venkata Rao Midathana, Auteur ; Vijayanand S. Moholkar, Auteur . - 2009 . - pp. 7368–7377. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7368–7377 Mots-clés : Organic  pollutants  Ultrasound  Adsorption Résumé : In this paper we try to discern the physical mechanism of enhancement of adsorption of organic pollutants with application of ultrasound. An attempt is made to discriminate between the contribution made by various physical effects of ultrasound and cavitation, viz., microstreaming, microturbulence, and acoustic (or shock) waves, which could generate convection in the medium and enhance the process of adsorption. A dual approach of coupling experimental results to the simulations of a bubble dynamics model has been adopted. Adsorption of three aromatic pollutants (viz., nitrobenzene, phenol, and p-nitrophenol) onto activated carbon has been chosen as a model process. Correlation of the experimental and simulation results reveals that the extent of adsorption in the presence of ultrasound shows an optimum with the intensity of convection generated in the medium by the cavitation bubbles. The microturbulence generated by cavitation bubbles makes a useful contribution to the enhancement of adsorption. This is attributed to the continuous nature of microturbulence with moderate liquid velocities. On the other hand, acoustic waves emitted by the cavitation bubbles render an adverse effect on the process. This is attributed to the discrete nature and high pressure amplitude of the waves, which create excessively high convection in the medium, causing desorption of the pollutant. The chemical nature of the pollutant is also found to influence the enhancement effect of ultrasound. For hydrophobic pollutants, the ultrasonic enhancement is more pronounced than for hydrophilic pollutants under otherwise similar conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900049e

Physical mechanism of ultrasound-assisted synthesis of biodiesel / Abhishek Kalva in Industrial & engineering chemistry research, Vol. 48 N°1 (Janvier 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 534-544 Titre : Physical mechanism of ultrasound-assisted synthesis of biodiesel Type de document : texte imprimé Auteurs : Abhishek Kalva, Editeur scientifique ; Thirugnanasambandam Sivasankar, Editeur scientifique ; Vijayanand S. Moholkar, Editeur scientifique Année de publication : 2009 Article en page(s) : P. 534-544 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ultrasound-Assisted  Physical  Mechanism  Synthesis  of  Biodiesel Résumé : Acceleration of the transesterification reaction for synthesis of biodiesel by application of ultrasound is known. This paper tries to establish the mechanism of this enhancement by discriminating between physical and chemical effects of ultrasound. Experiments with different conditions have been coupled to a bubble dynamics model. It is revealed that influence of ultrasound on transesterification reaction is of purely physical nature. Formation of fine emulsion between oil and alcohol due to microturbulence generated by cavitation bubbles generates enormous interfacial area, which accelerates the reaction. For the power input used in the present experiments, the temperature peak reached in transient collapse of cavitation bubble in methanol is found to be too low to produce any radical species, which can induce transesterification reaction. The yield of the reaction is found to have an optimum with respect to alcohol to oil molar ratio. This result is attributed to the difference in intensity of microturbulence produced by cavitation bubbles in oil and methanol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800269g [article] Physical mechanism of ultrasound-assisted synthesis of biodiesel [texte imprimé] / Abhishek Kalva, Editeur scientifique ; Thirugnanasambandam Sivasankar, Editeur scientifique ; Vijayanand S. Moholkar, Editeur scientifique . - 2009 . - P. 534-544. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N°1 (Janvier 2009) . - P. 534-544 Mots-clés : Ultrasound-Assisted  Physical  Mechanism  Synthesis  of  Biodiesel Résumé : Acceleration of the transesterification reaction for synthesis of biodiesel by application of ultrasound is known. This paper tries to establish the mechanism of this enhancement by discriminating between physical and chemical effects of ultrasound. Experiments with different conditions have been coupled to a bubble dynamics model. It is revealed that influence of ultrasound on transesterification reaction is of purely physical nature. Formation of fine emulsion between oil and alcohol due to microturbulence generated by cavitation bubbles generates enormous interfacial area, which accelerates the reaction. For the power input used in the present experiments, the temperature peak reached in transient collapse of cavitation bubble in methanol is found to be too low to produce any radical species, which can induce transesterification reaction. The yield of the reaction is found to have an optimum with respect to alcohol to oil molar ratio. This result is attributed to the difference in intensity of microturbulence produced by cavitation bubbles in oil and methanol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800269g