Soda pulping of Miscanthus sinensis. Effects of operational variables on pulp yield and lignin solubilization

A simple system for the production of alkaline pulps from Miscanthus sinensis was studied. Miscanthus sinensis is a non-woody plant species of rapid growth with reported yields of up to 40 t ha−1 year−1. A first-order full-factorial design was used to analyse and evaluate the effects of variables on pulp yield and lignin solubilization. The variables studied and their respectives ranges of variation were as follows: liquid to solid ratio, 6–10; temperature, 80–100°C; time, 0–240 min; NaOH concentration, 1–2%. Good pulp yields (about 60%) and acceptable values of residual lignin (less than 10%) were obtained in the best conditions, which meant a percentage lignin solubilization close to 80%. This study also showed that selectivity of the system was independent of the working conditions and this could be summarized in the following formula: dissolved lignin/weight LOSSES = 0•4.