Modelling Organosolv Pulping of Hemp

Hemp (Cannabis sativa) stem wood chips were pulped in ethanol/water mixtures without additives, using lab-scale batch reactors. A central composite design was used to investigate autocatalyzed Organosolv pulping and to study the effect of process variables on pulp quality and yield. A second order polynomial regression model, using four independent process variables, was found to be appropriate for describing organosolv pulping of hemp stem wood fibres. The derived equations were able to predict the kappa number, the yield and the degree of polymerization of the pulp, with “adjusted R²” values of 76.3%, 94.3% and 83.9%, respectively. The overall Optimum pulping conditions, which maximize yield while subject to the restrictions of a kappa number lower than 30 and a DP exceeding 2500, were estimated at a pulping time of 171 minutes, a pulping temperature of 196°C, an ethanol concentration of 65% and a 1/w ratio of 13 ml g^-1.