MODELING ORGANOSOLV PULPING OF HEMP

Hemp (Cannabis sativa) stem wood chips were pulped in ethanol/water mi xtures without additives, using lab-scale batch reactors. A central co mposite design was used to investigate autocatalyzed organosolv pulpin g and to study the effect of process variables on pulp quality and yie ld. A second order polynomial regression model, using four independent process variables, was found to be appropriate for describing organos olv pulping of hemp stem wood fibres. The derived equations were able to predict the kappa number, the yield and the degree of polymerizatio n of the pulp, with ''adjusted R(2)'' 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 mi nutes, a pulping temperature of 196 degrees C, an ethanol concentratio n of 65% and a 1/w ratio of 13 ml g(-1).