Measuring the concentration of carboxylic acid groups in torrefied spruce wood

Tooran Khazraie Shoulaifar, Nikolai De Martini, Ari Ivaska, Pedro Fardim, Mikko Hupa

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    46 Citations (Scopus)


    Torrefaction is moderate thermal treatment (similar to 200-300 degrees C) to improve the energy density, handling and storage properties of biomass fuels. In biomass, carboxylic sites are partially responsible for its hygroscopic. These sites are degraded to varying extents during torrefaction. In this paper, we apply methylene blue sorption and potentiometric titration to measure the concentration of carboxylic acid groups in spruce wood torrefied for 30 min at temperatures between 180 and 300 degrees C. The results from both methods were applicable and the values agreed well. A decrease in the equilibrium moisture content at different humidity was also measured for the torrefied wood samples, which is in good agreement with the decrease in carboxylic acid sites. Thus both methods offer a means of directly measuring the decomposition of carboxylic groups in biomass during torrefaction as a valuable parameter in evaluating the extent of torrefaction which provides new information to the chemical changes occurring during torrefaction.
    Original languageUndefined/Unknown
    Pages (from-to)338–343
    Number of pages6
    JournalBioresource Technology
    Publication statusPublished - 2012
    MoE publication typeA1 Journal article-refereed


    • Carboxylic acid groups
    • Methylene blue sorption
    • Potentiometric titration
    • Spruce wood
    • Torrefaction

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