Documents disponibles écrits par cet auteur

Critical properties and normal boiling temperature of ionic liquids. update and a new consistency test / José O. Valderrama in Industrial & engineering chemistry research, Vol. 51 N° 22 (Juin 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7838-7844 Titre : Critical properties and normal boiling temperature of ionic liquids. update and a new consistency test Type de document : texte imprimé Auteurs : José O. Valderrama, Auteur ; Luis A. Forero, Auteur ; Roberto E. Rojas, Auteur Année de publication : 2012 Article en page(s) : pp. 7838-7844 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Ionic  liquid  Boiling  Critical  property Résumé : The group contribution method proposed by Valderrama and Robles in 2007 and extended by Valderrama and Rojas in 2009 to estimate the critical properties of ionic liquids is revised and an additional test for determining the consistency of the estimated properties is proposed. The new testing method includes the calculation of the saturation pressure at the normal boiling temperature using an equation of state and an accurate model to represent the temperature function of the attractive term in the equation of state. In determining the vapor pressure, the critical temperature, the critical pressure, the critical volume, and the acentric factor determined by group contribution are included. The proposed method complements the previous density test of the authors that tested the critical temperature, the critical volume, and the normal boiling temperature only. A total of 1130 ionic liquids are considered in this work, and double checking, using the density and the normal vapor pressure, is applied. Also, a spreadsheet file that allows any reader to calculate and check the critical properties of other ionic liquids containing any of the 44 groups defined by the method is provided. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968340 [article] Critical properties and normal boiling temperature of ionic liquids. update and a new consistency test [texte imprimé] / José O. Valderrama, Auteur ; Luis A. Forero, Auteur ; Roberto E. Rojas, Auteur . - 2012 . - pp. 7838-7844. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 22 (Juin 2012) . - pp. 7838-7844 Mots-clés : Ionic  liquid  Boiling  Critical  property Résumé : The group contribution method proposed by Valderrama and Robles in 2007 and extended by Valderrama and Rojas in 2009 to estimate the critical properties of ionic liquids is revised and an additional test for determining the consistency of the estimated properties is proposed. The new testing method includes the calculation of the saturation pressure at the normal boiling temperature using an equation of state and an accurate model to represent the temperature function of the attractive term in the equation of state. In determining the vapor pressure, the critical temperature, the critical pressure, the critical volume, and the acentric factor determined by group contribution are included. The proposed method complements the previous density test of the authors that tested the critical temperature, the critical volume, and the normal boiling temperature only. A total of 1130 ionic liquids are considered in this work, and double checking, using the density and the normal vapor pressure, is applied. Also, a spreadsheet file that allows any reader to calculate and check the critical properties of other ionic liquids containing any of the 44 groups defined by the method is provided. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25968340

Critical properties of ionic liquids. revisited / José O. Valderrama in Industrial & engineering chemistry research, Vol. 48 N° 14 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6890–6900 Titre : Critical properties of ionic liquids. revisited Type de document : texte imprimé Auteurs : José O. Valderrama, Auteur ; Roberto E. Rojas, Auteur Année de publication : 2009 Article en page(s) : pp. 6890–6900 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Ionic  liquids  Group  contribution  method Résumé : The group contribution method proposed by Valderrama and Robles in 2007 and extended by Valderrama et al. in 2008 to estimate the critical properties of ionic liquids is revised and new groups have been included. The method originally proposed has been used by several authors in applications such as high pressure phase equilibrium, density correlations, heat capacity estimations, and consistency tests for mixture data. Therefore, it is important to have a consistent and reliable method so all applications consider the same assumptions and values for the critical properties. The values previously reported by the authors are recalculated, unifying criteria for the names of the ionic liquids, for the assignment of the groups forming the molecules, and for the equivalence of groups. Also, a spreadsheet file that allows any reader to calculate the critical properties of any ionic liquid containing the 44 groups defined by the method is provided as Supporting Information. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900250g [article] Critical properties of ionic liquids. revisited [texte imprimé] / José O. Valderrama, Auteur ; Roberto E. Rojas, Auteur . - 2009 . - pp. 6890–6900. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 14 (Juillet 2009) . - pp. 6890–6900 Mots-clés : Ionic  liquids  Group  contribution  method Résumé : The group contribution method proposed by Valderrama and Robles in 2007 and extended by Valderrama et al. in 2008 to estimate the critical properties of ionic liquids is revised and new groups have been included. The method originally proposed has been used by several authors in applications such as high pressure phase equilibrium, density correlations, heat capacity estimations, and consistency tests for mixture data. Therefore, it is important to have a consistent and reliable method so all applications consider the same assumptions and values for the critical properties. The values previously reported by the authors are recalculated, unifying criteria for the names of the ionic liquids, for the assignment of the groups forming the molecules, and for the equivalence of groups. Also, a spreadsheet file that allows any reader to calculate the critical properties of any ionic liquid containing the 44 groups defined by the method is provided as Supporting Information. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900250g

Density of ionic liquids using group contribution and artificial neural networks / José O. Valderrama in Industrial & engineering chemistry research, Vol. 48 N° 6 (Mars 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3254–3259 Titre : Density of ionic liquids using group contribution and artificial neural networks Type de document : texte imprimé Auteurs : José O. Valderrama, Auteur ; Alfonso Reátegui, Auteur ; Roberto E. Rojas, Auteur Année de publication : 2009 Article en page(s) : pp. 3254–3259 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Artificial  neural  networks  Ionic  liquids  Artificial  neural  network Résumé : Artificial neural networks and the concept of group contribution are simultaneously used to correlate and predict the density of ionic liquids. Different topologies of a multilayer feed forward artificial neural network were studied and the optimum architecture was determined. Density data from the literature for 103 ionic liquids with 399 data points have been used for training the network. To discriminate among the different substances, the molecular mass and the structure of the molecule, defined by the concepts of the classical group contribution methods, were given as input variables. The capabilities of the designed network were tested by predicting densities for situations not considered during the training process of the network (82 density data points for 24 ionic liquids). The results demonstrate that the chosen network and the group contribution method employed are able to estimate the density of ionic liquids with acceptable accuracy for engineering calculations. The program codes and the necessary input files to calculate the density for other ionic liquids are provided. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801113x [article] Density of ionic liquids using group contribution and artificial neural networks [texte imprimé] / José O. Valderrama, Auteur ; Alfonso Reátegui, Auteur ; Roberto E. Rojas, Auteur . - 2009 . - pp. 3254–3259. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 6 (Mars 2009) . - pp. 3254–3259 Mots-clés : Artificial  neural  networks  Ionic  liquids  Artificial  neural  network Résumé : Artificial neural networks and the concept of group contribution are simultaneously used to correlate and predict the density of ionic liquids. Different topologies of a multilayer feed forward artificial neural network were studied and the optimum architecture was determined. Density data from the literature for 103 ionic liquids with 399 data points have been used for training the network. To discriminate among the different substances, the molecular mass and the structure of the molecule, defined by the concepts of the classical group contribution methods, were given as input variables. The capabilities of the designed network were tested by predicting densities for situations not considered during the training process of the network (82 density data points for 24 ionic liquids). The results demonstrate that the chosen network and the group contribution method employed are able to estimate the density of ionic liquids with acceptable accuracy for engineering calculations. The program codes and the necessary input files to calculate the density for other ionic liquids are provided. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801113x