Documents disponibles écrits par cet auteur

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