Optimization of low-temperature oxygen-alkali pulping process for reed and analysis using response surface methodology

Reed was used as a raw material to develop a low-temperature oxygen-alkali pulping process, and a mathematical prediction model was established to evaluate the impact of process variables on pulping performance. Additionally, the dissolution behavior of reed’s chemical components was analyzed to elucidate the synergistic mechanism of oxygen-alkali pulping. The results revealed that optimal pulp performance was achieved at a maximum temperature of 114.5 °C, a retention time of 3.88 hours, and a sodium carbonate-to-sodium hydroxide molar ratio of 1/10. Under these conditions, the pulp yield reached 50.5%, with a brightness of 55.5% ISO, a viscosity of 465 mL/g, and a kappa number of 16.2. Notably, most of the silicon remains in the pulp, with only 34.1% migrating to the black liquor, thereby mitigating silica-related interference during alkali recovery. Variance analysis of the response surface confirmed that the investigated variables had significant impacts on all response indices, and the developed predictive model demonstrated high accuracy in forecasting the pulping performance of reed. Furthermore, the physical properties of the paper produced under these optimal conditions were superior to those of the paper obtained by using conventional high-temperature oxygen-alkali pulping processes.