Optimization of the pre-treatment of white sawdust (Triplochiton scleroxylon) by the organosolv process for the production of bioethanol

Abstract

The exploitation of our forests generates waste, amongst which sawdust produces approximately cubic meter per year. The objective of this work is to contribute to the improvement of the recovery process of this waste through the optimization of the pre-treatment stage of sawdust from Ayous (Triplochiton scleroxylon) by the organosolv process in order to produce bioethanol. To achieve this objective, Ayous sawdust was sampled and then characterized, followed by the pre-treatment through organosolv process. During pre-treatment, a composite experimental design centred on three factors (temperature, time, ethanol concentration) was used to study their effects on extraction of pentoses, reducing sugars and phenolic compounds. Analysis shows that Ayous sawdust contains 45.33 ± 5.5% cellulose, 30.32 ± 1.95% lignin and 20.03 ± 3.5% hemicellulose. To release the maximum of pentoses, reducing sugars and the minimum of phenolic compounds, an organosolv pre-treatment of this substrate should be carried out at 209.08 °C for 47.60 min with an ethanol–water ratio of 24.02%. Temperature is the factor having the most positive influence on the pre-treatment process whereas, ethanol concentration is not an essential factor. Organosolv pre-treatment is an effective process for delignification of the lignocellulosic structure of Ayous sawdust.