The effects of the initial concentration of effective alkali

H factor (ie

coupled time and temperature) on methanol formation in the eucalyptus pulping and residual alkali concentration in the pulping effluents were investigated. It was found that there existed a linear relationship between the effective alkali concentration and negative exponent of H factor for pulping process. From this observation

a mathematical model that takes account for the time-dependent concentration of effective alkali was established from the kinetic analysis for wood demethoxylation during pulping process. The results showed that the proposed model could predict methanol formation in kraft pulping at various process conditions with a good accuracy (R2 = 0.990). It was found from the results predicted by this model that the methanol formation was much more sensitive to pulping temperature than to initial concentration of effective alkali. The prediction of this model for formation amount of methanol at various process conditions could be a good guidance for control and reduction of methanol formation per unit mass removal of lignin in pulping process.