Improvement of enzymatic digestibility of wood by a sequence of optimized milling procedures with final vibratory tube mills for the amorphization of cellulose

Abstract

Abstract A three-stage wood milling process was investigated leading to coarse, fine and amorphization of milled wood (MW) as a pretreatment for enzymatic wood hydrolysis. An eccentric vibratory tube mill (EVTM) and a spring suspended vibratory tube mill (SSVTM) were found to be suitable for wood cellulose amorphization. Both methods gave rise to highly digestible and amorphous wood powders amenable to enzymatic hydrolysis. The SSVTM had superior energy efficiency. The resulting MW afforded a 70% sugar yield via enzymatic hydrolysis and the total energy consumption was around 1.5 kWh kg−1 oven-dried wood (odW) for all three milling stages. In contrast, EVTM consumed 17 kWh kg−1 odW energy. Accordingly, SSVTM has a high potential for preparing wood for enzymatic hydrolysis.