Optimization of the soda-ethanol delignification stage for a rice husk biorefinery

DAGNINO, P.E.; CHAMORRO, M.; FELISSIA, F.E.; AREA, M.C.

Industrial Crops and Products

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017 vol. 97 p. 156 - 165

0926-6690

The aim of this work was to optimize the delignification of the hemicelluloses-free fraction of rice husk to obtain fractions of lignin, cellulose, and inorganics, which could be valorized in the context of the rice husk biorefinery. The hemicelluloseswere pre-extracted from the raw material by dilute sulfuric acid, and a soda-ethanol-water process was used for delignification. Two experimentaldesigns were carried out to evaluate different ranges of the same variable s(strong and light conditions), aiming to promote maximal delignification ordelignify while protecting carbohydrates. The optimal delignifications point wereobtained using 13 and 8% of NaOH (%w/w on solid material), in a 50:50 and 54:46ethanol:water solution. In these conditions, 94.3 and 90.1% of lignin andalmost 100 and 40% of inorganics were removed from the solid, respectively. Theused soda-ethanol-water process can be defined as a soda process additivatedwith ethanol, showing significant advantages over soda-anthraquinone processfor the fractionation of lignocellulosic materials.