Documents disponibles écrits par cet auteur

Kinetics of aldehyde oxidation by chlorous acid / Tuula Lehtimaa 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. 2688–2693 Titre : Kinetics of aldehyde oxidation by chlorous acid Type de document : texte imprimé Auteurs : Tuula Lehtimaa, Auteur ; Susanna Kuitunen, Auteur ; Ville Tarvo, Auteur Année de publication : 2010 Article en page(s) : pp. 2688–2693 Note générale : industrial Chemistry Langues : Anglais (eng) Mots-clés : Kinetics  Aldehyde  Oxidation  Chlorous  Acid Résumé : Chlorous acid is known to react with aldehydes. This study investigated the oxidation kinetics of different aldehydes by chlorous acid. Reaction rates with chlorous acid at 25 °C were obtained for formaldehyde (11.0 M−1 s−1), vanillin (0.59 M−1 s−1), veratraldehyde (1.00 M−1 s−1), benzaldehyde (5.6 M−1 s−1), glucose (3.39 × 10−3 M−1 s−1), glycolaldehyde (39.0 M−1 s−1), and 5-formyl-2-furancarboxylic acid (5.2 M−1 s−1). The activation energies varied between 26 and 63 kJ/mol. The rate-determining step was shown to be the addition of chlorous acid to the aldehyde structure. The practical significance of the Cl(III) reaction with aldehyde structures in chlorine dioxide bleaching was discussed. It was concluded that various aldehydes present in cellulosic pulp are at least partly responsible for the consumption of Cl(III) in chlorine dioxide bleaching. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9018885 [article] Kinetics of aldehyde oxidation by chlorous acid [texte imprimé] / Tuula Lehtimaa, Auteur ; Susanna Kuitunen, Auteur ; Ville Tarvo, Auteur . - 2010 . - pp. 2688–2693. industrial Chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 6 (Mars 2010) . - pp. 2688–2693 Mots-clés : Kinetics  Aldehyde  Oxidation  Chlorous  Acid Résumé : Chlorous acid is known to react with aldehydes. This study investigated the oxidation kinetics of different aldehydes by chlorous acid. Reaction rates with chlorous acid at 25 °C were obtained for formaldehyde (11.0 M−1 s−1), vanillin (0.59 M−1 s−1), veratraldehyde (1.00 M−1 s−1), benzaldehyde (5.6 M−1 s−1), glucose (3.39 × 10−3 M−1 s−1), glycolaldehyde (39.0 M−1 s−1), and 5-formyl-2-furancarboxylic acid (5.2 M−1 s−1). The activation energies varied between 26 and 63 kJ/mol. The rate-determining step was shown to be the addition of chlorous acid to the aldehyde structure. The practical significance of the Cl(III) reaction with aldehyde structures in chlorine dioxide bleaching was discussed. It was concluded that various aldehydes present in cellulosic pulp are at least partly responsible for the consumption of Cl(III) in chlorine dioxide bleaching. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie9018885

Model for degradation of galactoglucomannan in hot water extraction conditions / Juha A. Visuri in Industrial & engineering chemistry research, Vol.51 N° 31 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol.51 N° 31 (Août 2012) . - pp. 10338–10344 Titre : Model for degradation of galactoglucomannan in hot water extraction conditions Type de document : texte imprimé Auteurs : Juha A. Visuri, Auteur ; Tao Song, Auteur ; Susanna Kuitunen, Auteur Année de publication : 2012 Article en page(s) : pp. 10338–10344 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Hot  water  Modeling Résumé : A kinetic analysis is presented for the homogeneous degradation of galactoglucomannan (GGM) in hot water extraction conditions. In the experiments used for constructing the kinetic model, GGM extracted from spruce wood meal was treated at temperatures from 150 to 170 °C and in buffered pH 3.8―4.2. The hydrolysis of glycosidic bonds in GGM was modeled as a random process which is catalyzed by hydrogen ions. The real hydrogen ion concentration at the reaction temperatures was estimated. The Arrhenius equation was used to describe the temperature dependence of the hydrolysis rate and an activation energy of 102 kj/mol was obtained for the reaction. The presented model predicts accurately the evolution of the molecular weight distribution with lower computational load than other similar models. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26234064 [article] Model for degradation of galactoglucomannan in hot water extraction conditions [texte imprimé] / Juha A. Visuri, Auteur ; Tao Song, Auteur ; Susanna Kuitunen, Auteur . - 2012 . - pp. 10338–10344. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol.51 N° 31 (Août 2012) . - pp. 10338–10344 Mots-clés : Hot  water  Modeling Résumé : A kinetic analysis is presented for the homogeneous degradation of galactoglucomannan (GGM) in hot water extraction conditions. In the experiments used for constructing the kinetic model, GGM extracted from spruce wood meal was treated at temperatures from 150 to 170 °C and in buffered pH 3.8―4.2. The hydrolysis of glycosidic bonds in GGM was modeled as a random process which is catalyzed by hydrogen ions. The real hydrogen ion concentration at the reaction temperatures was estimated. The Arrhenius equation was used to describe the temperature dependence of the hydrolysis rate and an activation energy of 102 kj/mol was obtained for the reaction. The presented model predicts accurately the evolution of the molecular weight distribution with lower computational load than other similar models. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26234064

The kinetics and stoichiometry of the reaction between hypochlorous acid and chlorous acid in mildly acidic solutions / Ville Tarvo in Industrial & engineering chemistry research, Vol. 48 N° 13 (Juillet 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. Titre : The kinetics and stoichiometry of the reaction between hypochlorous acid and chlorous acid in mildly acidic solutions Type de document : texte imprimé Auteurs : Ville Tarvo, Auteur ; Tuula Lehtimaa, Auteur ; Susanna Kuitunen, Auteur Année de publication : 2009 Article en page(s) : pp. Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hypochlorous  acid  Chlorous  acid  Stoichiometry  Kinetics Résumé : The kinetics and stoichiometry of the reaction between hypochlorous acid and chlorous acid was studied under mildly acidic conditions (pH = 2.5−4.7). The experiments were conducted in dilute solutions (10−4−10−3 M) at T = 5−25 °C. External buffer compounds were not used. Chlorous acid, chlorine dioxide, and chlorate concentrations were monitored with titrimetric methods. Rate coefficients and activation energies were determined for the five main steps of the kinetic model (others were adopted from literature). Both hypochlorous acid and chlorine were found to react at an appreciable rate with chlorous acid/chlorite. Chloride ion was found to promote both the overall reaction rate and chlorine dioxide/chlorate ratio. The results may be exploited in optimizing the red-ox efficiency of technical chlorine dioxide bleaching processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801798m [article] The kinetics and stoichiometry of the reaction between hypochlorous acid and chlorous acid in mildly acidic solutions [texte imprimé] / Ville Tarvo, Auteur ; Tuula Lehtimaa, Auteur ; Susanna Kuitunen, Auteur . - 2009 . - pp. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 13 (Juillet 2009) . - pp. Mots-clés : Hypochlorous  acid  Chlorous  acid  Stoichiometry  Kinetics Résumé : The kinetics and stoichiometry of the reaction between hypochlorous acid and chlorous acid was studied under mildly acidic conditions (pH = 2.5−4.7). The experiments were conducted in dilute solutions (10−4−10−3 M) at T = 5−25 °C. External buffer compounds were not used. Chlorous acid, chlorine dioxide, and chlorate concentrations were monitored with titrimetric methods. Rate coefficients and activation energies were determined for the five main steps of the kinetic model (others were adopted from literature). Both hypochlorous acid and chlorine were found to react at an appreciable rate with chlorous acid/chlorite. Chloride ion was found to promote both the overall reaction rate and chlorine dioxide/chlorate ratio. The results may be exploited in optimizing the red-ox efficiency of technical chlorine dioxide bleaching processes. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801798m