Integrated forest biorefinery applied to a CTMP process: pre-extraction of acetic acid

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University of New Brunswick


Acetic acid is one of the promising bio-products in the value prior to pulping (VPP) concept, which is one of the options for Integrated Forest Bio-refinery. In a typical chemi-thermo-mechanical (CTMP) process the chemical pre-treatment can be easily retrofitted into the pre-extraction stage, the potential of pre-extraction of acetic acid and effect on pulp properties was evaluated in this study. The pre-extraction yield of acetic acid increased with the increase of cooking time and temperature. The maximum yield was 31.25% at 150 °C and 60 minutes right after the cooking in the digester manufactured by M/K System, Inc. The pre-extraction yield increased to 42.05% after the cooked chips were broken down into pulps, indicating that some of the released acetic acid was trapped inside chips and a post-mechanical treatment was required for acetic acid to be easily diffused into the liquid phase. Pilot trials at selected conditions indicated that compared with the control, at a similar specific refining energy and freeness, pulps produced with acid pre-extraction had lower bulk, less long fibers, lower brightness but similar or better strength properties.