Optimization and modeling of ethanol–alkali pulping process of bamboo (Yushania alpina) by response surface methodology

Abstract

Response surface methodology based on the central composite design was used to investigate modeling and optimizing the individual and interactive effects of independent process variables (temperature, pulping time, ethanol concentration and alkali concentration) on the yield, kappa number and brightness of the pulp produced from the bamboo species Yushania alpina. Based on the central composite design, quadratic models and two-factor interactions were developed and correlated the pulp yield, kappa number and brightness of the pulps. The most significant parameters that affect the pulp yield, kappa number and brightness of the pulp were found to be temperature, ethanol concentration and alkali concentration, respectively. The optimum process variables were found at a cooking temperature of 162.30 °C, cooking time of 180 min, ethanol concentration of 60% and alkali concentration of 18.03% producing maximum pulp yield of 53.56% and brightness of 63.85%, and minimum kappa number of 11.65, and desirability of 0.882. In addition, the chemical analysis of Y. alpina chips was compared with different bamboo species. The predicted optimum conditions provided tensile index, burst index and tear index of 48.25 kN m/kg, 2.95 kPa m2 and 2.80 N m2/kg, respectively, and were experimentally confirmed. In general, the findings of the study show that pulp produced from the bamboo species Y. alpina is a suitable raw material for the paper and pulp industry.