Abstract
Certain properties of wood can be improved with thermal modification, allowing its application fields to be considerably extended without the use of any chemical additives. This study focuses on the chemical investigation of hardwood (oak, beech, ash) products heat-treated with an industrial scale vacuum-press dewatering method (Vacu³) as well as on the evaluation of the parameters of the condensation water exhausted during the treatment. Wood modification was carried out at 195 and 210 °C. The pH value, loss of VOCs and total phenols were determined from the samples. Waste waters collected after the treatment cycles were investigated for pH, conductivity, COD, VOCs, total phenols and also for possible utilizable compounds. Release of VOCs from wood can be a health concern. Results show that the losses of the measured components were quite low. The composition of the highly acidic waste waters also depends on wood species, containing mostly phenolic compounds, aldehydes and acids. Possible ways for the utilization of these components need to be worked out in the future.
Zusammenfassung
Mittels thermischer Modifizierung können ausgewählte Eigenschaften des Holzes signifikant verbessert werden. Dabei können die Anwendungsbereiche ohne den Zusatz von chemischen Stoffen erweitert werden. In der Arbeit werden die chemischen Eigenschaften von thermisch nach dem Vakuum-Press-Trocknungsverfahren (Vacu3) modifiziertem Laubholz (Eiche, Buche, Esche) sowie während der Wärmebehandlung entstehende Kondenswasser analysiert. Die Behandlungstemperaturen betrugen 195 und 210 °C. Es wurden der pH-Wert und die Abgabe von flüchtigen organischen Stoffen (VOC) sowie der Gesamtphenolgehalt gemessen. Die Abwässer wurden auf pH-Wert, Leitfähigkeit und Chemischen Sauerstoffbedarf (CSB) untersucht. VOC Emissionen sind insbesondere beim Einsatz des Holzes im Innenbereich (Parkett, Möbel) von großer Bedeutung. Die Ergebnisse zeigten, dass die Emissionen der untersuchten Verbindungen niedrig waren. Die Zusammensetzung der stark sauren Abwässer bestand meist aus Phenolen, Aldehyden und Säuren. Mögliche Wege zur Nutzung der Komponenten müssen in der Zukunft erarbeitet werden.
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Hofmann, T., Wetzig, M., Rétfalvi, T. et al. Heat-treatment with the vacuum-press dewatering method: chemical properties of the manufactured wood and the condensation water. Eur. J. Wood Prod. 71, 121–127 (2013). https://doi.org/10.1007/s00107-012-0657-0
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DOI: https://doi.org/10.1007/s00107-012-0657-0