Optimization strategy and model construction for the soda-anthraquinone pulping process of Arundo donax L.

This study focuses on the production of high-quality chemical pulp utilizing Arundo donax L. as a feedstock via soda-anthraquinone (AQ) pulping process. By orthogonal design experiments, the optimum process conditions for soda-AQ pulping of Arundo donax L. were determined as an alkali dosage of 20% NaOH, cooking temperature of 160 ℃ and holding time of 90 min. Under these conditions, the resulted pulp exhibited the best comprehensive properties, with the yield, kappa number and viscosity of 46.19%, 22.96 mL/g and 1068 mL/g, respectively. Moreover, a mathematical model for lignin dissolution behavior from Arundo donax L. under different cooking conditions was constructed using the least squares method. The variance analysis showed that this model had high statistical significance, with a R 2 value of 0.9798 and a P-value less than 0.05, implying a predictive confidence level up to 99%. Furthermore, the paper made from Arundo donax L. soda-AQ pulp under the optimal parameters displayed excellent physical properties, including a tensile index of 78.5 N·m/g, burst index of 4.08 kPa·m 2 /g, tear index of 6.91 mN·m 2 /g and ring crush index of 14.25 N·m/g. This outstanding physical strength was relevant to the dense fiber network emerged on the surface morphology of the formed paper. Moreover, the brightness of the as-prepared Arundo donax L. paper was as high as 21.7% ISO. In addition, X-ray diffraction analysis indicated that the preferred alkali dosage for soda-AQ pulping of Arundo donax L. was 20% NaOH, which resulted in a crystallinity index of 60.93% for Arundo donax L. soda-AQ pulp. This work proposed a new soda-AQ pulping process for Arundo donax L. , which demonstrated the potential of Arundo donax L. as a sustainable alternative to other non-wood feedstocks for alkaline chemical pulp production.