Documents disponibles écrits par cet auteur

Advanced oxidation of trace organics in water by hydrogen peroxide solar photolysis / Mario R. Rojas in Industrial & engineering chemistry research, Vol. 50 N° 22 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12479–12487 Titre : Advanced oxidation of trace organics in water by hydrogen peroxide solar photolysis Type de document : texte imprimé Auteurs : Mario R. Rojas, Auteur ; Cary Leung, Auteur ; Daniel Whitley, Auteur Année de publication : 2012 Article en page(s) : pp. 12479–12487 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Oxidation  Solar  photolysis Résumé : Solar-UV/H2O2 advanced oxidation for destruction of trace organics was investigated under a variety of operating conditions in homogeneous, laboratory-scale batch reactor experiments. Fluorescein and p-cresol were selected as representative targets in the experiments. Half times for degradation of p-cresol ranged between 500 min with 2 mM H2O2 and 20 min with 50 mM H2O2 during high-solar irradiance experiments (around noon on July 15th). A kinetic model, previously developed for monochromatic light, was adapted for use with solar UV irradiance, using (i) calculated ground-level solar spectral irradiance for the date and time of the experiments and (ii) wavelength-dependent light attenuation in the reaction mixture. The model accurately represents experimental data without adjustable parameters. Model output included the time-dependent pH arising from complete mineralization of the targets. Observed radical scavenging effects were correctly predicted by the kinetic model. Contaminant transformation was also measured in a municipal secondary wastewater effluent matrix. Here, 2-D fluorescence spectroscopy was used as a measure of the time-dependent bulk organic characteristics in treated wastewater. Results indicated that solar-UV/H2O2 advanced oxidation is capable of eliminating or drastically reducing the concentrations of organic constituents that remain in conventionally treated municipal wastewater effluent. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201381j [article] Advanced oxidation of trace organics in water by hydrogen peroxide solar photolysis [texte imprimé] / Mario R. Rojas, Auteur ; Cary Leung, Auteur ; Daniel Whitley, Auteur . - 2012 . - pp. 12479–12487. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12479–12487 Mots-clés : Oxidation  Solar  photolysis Résumé : Solar-UV/H2O2 advanced oxidation for destruction of trace organics was investigated under a variety of operating conditions in homogeneous, laboratory-scale batch reactor experiments. Fluorescein and p-cresol were selected as representative targets in the experiments. Half times for degradation of p-cresol ranged between 500 min with 2 mM H2O2 and 20 min with 50 mM H2O2 during high-solar irradiance experiments (around noon on July 15th). A kinetic model, previously developed for monochromatic light, was adapted for use with solar UV irradiance, using (i) calculated ground-level solar spectral irradiance for the date and time of the experiments and (ii) wavelength-dependent light attenuation in the reaction mixture. The model accurately represents experimental data without adjustable parameters. Model output included the time-dependent pH arising from complete mineralization of the targets. Observed radical scavenging effects were correctly predicted by the kinetic model. Contaminant transformation was also measured in a municipal secondary wastewater effluent matrix. Here, 2-D fluorescence spectroscopy was used as a measure of the time-dependent bulk organic characteristics in treated wastewater. Results indicated that solar-UV/H2O2 advanced oxidation is capable of eliminating or drastically reducing the concentrations of organic constituents that remain in conventionally treated municipal wastewater effluent. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201381j

Modeling of advanced oxidation of trace organic contaminants by hydrogen peroxide photolysis and fenton’s reaction / Mario R. Rojas in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11331–11343 Titre : Modeling of advanced oxidation of trace organic contaminants by hydrogen peroxide photolysis and fenton’s reaction Type de document : texte imprimé Auteurs : Mario R. Rojas, Auteur ; Fernando Perez, Auteur ; Daniel Whitley, Auteur Année de publication : 2011 Article en page(s) : pp. 11331–11343 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hydrogen  Photolysis Résumé : The kinetics of nonylphenol and p-cresol destruction by hydrogen peroxide photolysis and Fenton’s reaction was investigated under a variety of operating conditions in homogeneous, laboratory-scale batch reactor experiments. Models with no adjustable parameters successfully accounted for radical initiation by photolysis of H2O2 or radical initiation by Fenton’s mechanism, reaction of organic targets with hydroxyl radical, and radical scavenging and recombination mechanisms, as well as changes in solution pH due to evolution of carbon dioxide because of target mineralization. Simulations of the UV/H2O2 and Fenton-based models can be used to anticipate the kinetics of advanced oxidation involving any target compound for which there is a known apparent second-order rate constant for reaction with hydroxyl radical. The presence of radical scavengers was successfully treated by the model, suggesting that the model can be generalized to the treatment of complex matrixes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101592p [article] Modeling of advanced oxidation of trace organic contaminants by hydrogen peroxide photolysis and fenton’s reaction [texte imprimé] / Mario R. Rojas, Auteur ; Fernando Perez, Auteur ; Daniel Whitley, Auteur . - 2011 . - pp. 11331–11343. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11331–11343 Mots-clés : Hydrogen  Photolysis Résumé : The kinetics of nonylphenol and p-cresol destruction by hydrogen peroxide photolysis and Fenton’s reaction was investigated under a variety of operating conditions in homogeneous, laboratory-scale batch reactor experiments. Models with no adjustable parameters successfully accounted for radical initiation by photolysis of H2O2 or radical initiation by Fenton’s mechanism, reaction of organic targets with hydroxyl radical, and radical scavenging and recombination mechanisms, as well as changes in solution pH due to evolution of carbon dioxide because of target mineralization. Simulations of the UV/H2O2 and Fenton-based models can be used to anticipate the kinetics of advanced oxidation involving any target compound for which there is a known apparent second-order rate constant for reaction with hydroxyl radical. The presence of radical scavengers was successfully treated by the model, suggesting that the model can be generalized to the treatment of complex matrixes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101592p

Two - layer model for horizontal pipe flow of newtonian and non - newtonian settling dense slurries / Mario R. Rojas in Industrial & engineering chemistry research, Vol. 51 N° 20 (Mai 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7095-7103 Titre : Two - layer model for horizontal pipe flow of newtonian and non - newtonian settling dense slurries Type de document : texte imprimé Auteurs : Mario R. Rojas, Auteur ; A. Eduardo Saez, Auteur Année de publication : 2012 Article en page(s) : pp. 7095-7103 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Sedimentation  Pipe  flow  Modeling Résumé : The steady-state flow of Newtonian and non-Newtonian dense aqueous slurries in horizontal pipes has been analyzed using a two-layer model, consisting of a top layer of flowing suspension and a bottom bed of stationary or moving particles. The coarse solids used have a wide range of particle density and particle size distributions. The fluids studied were designed to simulate U.S. Department of Energy Hanford site waste slurries. The most important changes from previous models include an independent settling analysis for different particle size fractions, effects of particle shape on settling velocity, and a new correlation for the turbulent particle dispersivity. The results indicate that the turbulent dispersivity of settling particles is sensitive to particle size and density. The model gives good estimation of the critical deposition velocity as the minimum of the pressure drop versus superficial slurry velocity relation. The existence of a stationary layer can be observed and predicted by the model under laminar and turbulent flow conditions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925051 [article] Two - layer model for horizontal pipe flow of newtonian and non - newtonian settling dense slurries [texte imprimé] / Mario R. Rojas, Auteur ; A. Eduardo Saez, Auteur . - 2012 . - pp. 7095-7103. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 20 (Mai 2012) . - pp. 7095-7103 Mots-clés : Sedimentation  Pipe  flow  Modeling Résumé : The steady-state flow of Newtonian and non-Newtonian dense aqueous slurries in horizontal pipes has been analyzed using a two-layer model, consisting of a top layer of flowing suspension and a bottom bed of stationary or moving particles. The coarse solids used have a wide range of particle density and particle size distributions. The fluids studied were designed to simulate U.S. Department of Energy Hanford site waste slurries. The most important changes from previous models include an independent settling analysis for different particle size fractions, effects of particle shape on settling velocity, and a new correlation for the turbulent particle dispersivity. The results indicate that the turbulent dispersivity of settling particles is sensitive to particle size and density. The model gives good estimation of the critical deposition velocity as the minimum of the pressure drop versus superficial slurry velocity relation. The existence of a stationary layer can be observed and predicted by the model under laminar and turbulent flow conditions. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25925051