Documents disponibles écrits par cet auteur

Application of a Temperature-Dependmiempirical thermodynamic ion-exchange model to a multicomponent natural zeolite system / Kathryn A. Mumford in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8347–8354 Titre : Application of a Temperature-Dependmiempirical thermodynamic ion-exchange model to a multicomponent natural zeolite system Type de document : texte imprimé Auteurs : Kathryn A. Mumford, Auteur ; David C. Shallcross, Auteur ; Ian Snape, Auteur ; Geoff W. Stevens, Auteur Année de publication : 2008 Article en page(s) : p. 8347–8354 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Semiempirical  thermodynamic Résumé : A recently developed temperature-dependent semiempirical thermodynamic ion-exchange model is used to predict ion-exchange equilibrium behavior of a binary and ternary system onto a natural zeolite material. The ion-exchange system involves the cations ammonium, potassium, and calcium, at chloride concentrations ranging from 0.005 to 0.25 M and temperatures ranging from 4.0 to 40.0 °C ± 0.2 °C. The model describes the ion-exchange behavior well, considering the natural variability of the zeolite material. En ligne : http://pubs.acs.org/toc/iecred/47/21 [article] Application of a Temperature-Dependmiempirical thermodynamic ion-exchange model to a multicomponent natural zeolite system [texte imprimé] / Kathryn A. Mumford, Auteur ; David C. Shallcross, Auteur ; Ian Snape, Auteur ; Geoff W. Stevens, Auteur . - 2008 . - p. 8347–8354. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8347–8354 Mots-clés : Semiempirical  thermodynamic Résumé : A recently developed temperature-dependent semiempirical thermodynamic ion-exchange model is used to predict ion-exchange equilibrium behavior of a binary and ternary system onto a natural zeolite material. The ion-exchange system involves the cations ammonium, potassium, and calcium, at chloride concentrations ranging from 0.005 to 0.25 M and temperatures ranging from 4.0 to 40.0 °C ± 0.2 °C. The model describes the ion-exchange behavior well, considering the natural variability of the zeolite material. En ligne : http://pubs.acs.org/toc/iecred/47/21

Effect of hydrocarbons on the separation of carbon dioxide from methane through a polyimide gas separation membrane / Raza Hasan in Industrial & engineering chemistry research, Vol. 48 N° 11 (Juin 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 11 (Juin 2009) . - pp. 5415–5419 Titre : Effect of hydrocarbons on the separation of carbon dioxide from methane through a polyimide gas separation membrane Type de document : texte imprimé Auteurs : Raza Hasan, Auteur ; Colin A. Scholes, Auteur ; Geoff W. Stevens, Auteur Année de publication : 2009 Article en page(s) : pp. 5415–5419 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Carbon  dioxide  Membrane  gas  separation  Polymeric  membrane Résumé : The removal of carbon dioxide from natural gas by membrane gas separation is an important process in upgrading the gas for consumers. Hydrocarbons associated with natural gas have the potential to influence the CO2 separation performance of membranes. Here, a glassy polymeric membrane of poly (4,4′-hexafluoroisopropylidene diphthalic anhydride-2,3,5,6-tetramethyl-1,4-phenylenediamine) (6FDA-TMPDA) was exposed to hexane and toluene at different partial pressures in a 90% CH4−10% CO2 gas mixture. The permeability of CO2 and CH4, as well as the selectivity, declined over time as both hexane and toluene competitively sorbed into the membrane. The resulting behavior fit the dual-sorption model for polymeric membrane separation and indicated Langmuir affinity constants of 0.13 ± 0.03 atm−1 for methane, 240 ± 100 atm−1 for hexane, and 980 ± 500 atm−1 for toluene (fugacity basis). The kinetics of the permeability decline were faster than that of the permeability recovery after the hydrocarbon contaminant was removed which may indicate that desorption from the Langmuir voids is the rate controlling step. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801537g [article] Effect of hydrocarbons on the separation of carbon dioxide from methane through a polyimide gas separation membrane [texte imprimé] / Raza Hasan, Auteur ; Colin A. Scholes, Auteur ; Geoff W. Stevens, Auteur . - 2009 . - pp. 5415–5419. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 11 (Juin 2009) . - pp. 5415–5419 Mots-clés : Carbon  dioxide  Membrane  gas  separation  Polymeric  membrane Résumé : The removal of carbon dioxide from natural gas by membrane gas separation is an important process in upgrading the gas for consumers. Hydrocarbons associated with natural gas have the potential to influence the CO2 separation performance of membranes. Here, a glassy polymeric membrane of poly (4,4′-hexafluoroisopropylidene diphthalic anhydride-2,3,5,6-tetramethyl-1,4-phenylenediamine) (6FDA-TMPDA) was exposed to hexane and toluene at different partial pressures in a 90% CH4−10% CO2 gas mixture. The permeability of CO2 and CH4, as well as the selectivity, declined over time as both hexane and toluene competitively sorbed into the membrane. The resulting behavior fit the dual-sorption model for polymeric membrane separation and indicated Langmuir affinity constants of 0.13 ± 0.03 atm−1 for methane, 240 ± 100 atm−1 for hexane, and 980 ± 500 atm−1 for toluene (fugacity basis). The kinetics of the permeability decline were faster than that of the permeability recovery after the hydrocarbon contaminant was removed which may indicate that desorption from the Langmuir voids is the rate controlling step. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801537g

Performance and scale-up of karr reciprocating plate extraction columns / Kathryn H. Smith in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p 8368–8375 Titre : Performance and scale-up of karr reciprocating plate extraction columns Type de document : texte imprimé Auteurs : Kathryn H. Smith, Auteur ; Tim Bowser, Auteur ; Geoff W. Stevens, Auteur Année de publication : 2008 Article en page(s) : p 8368–8375 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hydrodynamic  and  mass  System  of  kerosene/tributyl  phosphate− Résumé : The hydrodynamic and mass transfer performance of Karr reciprocating plate extraction columns with varying column diameters has been presented in order to examine how column performance changes with scale. An ideal liquid system of kerosene/tributyl phosphate−phenol−water was initially studied using a 50 mm diameter Karr column. Correlations were developed to predict the dispersed phase holdup, drop size distribution, and overall mass transfer coefficient over a range of operating conditions. This was followed by column performance studies using a phenolic alkaloid liquid system in Karr columns with diameters of 50, 100, and 300 mm. Overall results showed that there was no significant change in either the dispersed phase holdup or the mass transfer coefficient with column diameter. It was therefore concluded that overall column performance was independent of column diameter and the traditional Karr column scale-up equations were too conservative. This study also showed that factors such as droplet and plate coalescence, contamination of liquid systems, aging of column internals, and variation in physical properties can greatly influence the column’s performance and need to be carefully considered when designing a Karr column. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800581u#afn1 [article] Performance and scale-up of karr reciprocating plate extraction columns [texte imprimé] / Kathryn H. Smith, Auteur ; Tim Bowser, Auteur ; Geoff W. Stevens, Auteur . - 2008 . - p 8368–8375. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p 8368–8375 Mots-clés : Hydrodynamic  and  mass  System  of  kerosene/tributyl  phosphate− Résumé : The hydrodynamic and mass transfer performance of Karr reciprocating plate extraction columns with varying column diameters has been presented in order to examine how column performance changes with scale. An ideal liquid system of kerosene/tributyl phosphate−phenol−water was initially studied using a 50 mm diameter Karr column. Correlations were developed to predict the dispersed phase holdup, drop size distribution, and overall mass transfer coefficient over a range of operating conditions. This was followed by column performance studies using a phenolic alkaloid liquid system in Karr columns with diameters of 50, 100, and 300 mm. Overall results showed that there was no significant change in either the dispersed phase holdup or the mass transfer coefficient with column diameter. It was therefore concluded that overall column performance was independent of column diameter and the traditional Karr column scale-up equations were too conservative. This study also showed that factors such as droplet and plate coalescence, contamination of liquid systems, aging of column internals, and variation in physical properties can greatly influence the column’s performance and need to be carefully considered when designing a Karr column. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800581u#afn1