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Featured researches published by Tuula Lehtimaa.


Journal of Wood Chemistry and Technology | 2009

Chlorate Formation in Chlorine Dioxide Delignification—An Analysis via Elementary Kinetic Modeling

Ville Tarvo; Tuula Lehtimaa; Susanna Kuitunen; Ville Alopaeus; Tapani Vuorinen

Abstract Elementary kinetic modeling was used to study the mechanism of chlorate formation in chlorine dioxide delignification. Reaction conditions reflecting typical industrial processes (T = 50°C, pH 1.5–4) were examined. Fe mediated Cl(III) decomposition and a reaction between hypochlorous acid and chlorous acid (or their equilibrium counterparts) were found to be the major reaction routes responsible for chlorate formation at pH < 3. The latter route accounts for chlorate formation at pH ≥ 3. The rate of chlorous acid (HClO2) self-decomposition was too slow either to compete against the other routes (pH < 3) or to yield notable amounts of chlorate within the given time frame (pH ≥ 3). The results suggest that chlorate formation could be suppressed, without adverse effects on chlorine dioxide regeneration, by aiming for end pH 3–3.5, ensuring a moderate chloride ion concentration and by favoring concentrated solutions/suspensions.


Archive | 2007

Reactivity of hexenuronic acid in bleaching of eucalyptus kraft pulps

Tapani Vuorinen; Immanuel Adorjan; Anna Stiina Jääskeläinen; Tuula Lehtimaa; Katri Toikka; Zhen Zhou


59th Appita Annual Conference and Exhibition: Incorporating the 13th ISWFPC (International Symposium on Wood, Fibre and Pulping Chemistry), Auckland, New Zealand, 16-19 May 2005: Proceedings | 2005

Fundamental Modelling of Pulp Bleaching

Susanna Kuitunen; Ville Travo; Tuula Lehtimaa; Juhani Aittamaa


Archive | 2009

Development of AOX and OX in chlorine dioxide prebleaching of oxygen delignified softwood kraft pulp

Tuula Lehtimaa; Ville Tarvo; Susanna Kuitunen; Christian Järnefelt; Tapani Vuorinen


Archive | 2008

A method for the determination of stable and unstable AOX

Tuula Lehtimaa; Christian Järnefelt; Tapani Vuorinen


Archive | 2012

Modeling and kinetics of the reaction between hypochlorous and hexenuronic acids.

Naveen Kumar Chenna; Anna-Stiina Jääskeläinen; Tuula Lehtimaa; Susanna Kuitunen; Tapani Vuorinen


Archive | 2010

Lignin oxidation mechanism under oxygen delignification conditions - reaction pathways and modelling

Susanna Kuitunen; Anna Kalliola; Ville Tarvo; Tarja Tamminen; Stella Rovio; Tiina Liitiä; Taina Ohra-aho; Tuula Lehtimaa; Tapani Vuorinen; Ville Alopaeus


Archive | 2008

Evaluation of UV-VIS reflectance spectroscopy procedures in bleaching studies of hardwood pulps

Sirje Liukko; Tuula Lehtimaa; Tapani Vuorinen


Archive | 2008

Monitoring chlorine dioxide bleaching of hardwood pulps with UV-VIS reflectance spectroscopy

Sirje Liukko; Tuula Lehtimaa; Tapani Vuorinen


Archive | 2008

Evaluation of UV-VIS Reflectance Spectroscopy Procedures with Model Compounds and Bleached Kraft Pulps

Sirje Liukko; Tiina Liitiä; Tuula Lehtimaa; Tapani Vuorinen

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Juhani Aittamaa

Helsinki University of Technology

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Tiina Liitiä

VTT Technical Research Centre of Finland

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Anna Kalliola

VTT Technical Research Centre of Finland

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Anna-Stiina Jääskeläinen

VTT Technical Research Centre of Finland

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Stella Rovio

VTT Technical Research Centre of Finland

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