How Does Mass Transfer Affect the Effectiveness of AQ ? J . Samp and J . Li
نویسنده
چکیده
Many researchers have performed various studies to discover the reasons for the impressive catalytic effect of anthraquinone. Discussions and experiments have been conducted on the chemistry, kinetics, and physical properties of anthraquinone (AQ). However, most of the previous research has neglected the role of mass transfer in AQ pulping. This paper describes our analysis and interpretation of published experimental data based on both chemical (kinetics) and physical (mass transfer) effects. This new analysis of the historical data has led to a proposed "AQ uptake" mechanism that incorporates the mass transfer effects. Explanations are given for previously unexplained and/or underexplained phenomena involved in the AQ mechanism.* This analysis leads to an acknowledgment of physicochemical effects by which AQ is concentrated into the wood chips in the early stages of pulping. Previous work described the reason for this as the physical attraction between the AQ and the wood. However, our analysis of recent published data has shown that a more likely explanation is immobilization of AQ molecules due to reaction with lignin that causes solid AQ to precipitate out of the liquid phase and deposit on internal chip surfaces. Acknowledgment of the role of mass transfer in pulping with AQ could lead to improved pulping conditions that can take better advantage of the catalytic abilities of AQ.
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