Synergistic Effects between Hydrolysis Time and Microporous Structure in Poplar
Enzyme accessibility plays an important role in controlling the rate of conversion of cellulose to glucose in biomass. The goal of this study is to measure the cellulose accessibility due to the effect of dilute acid pretreatment (DAP) and enzymatic hydrolysis (EH) time of Populus biomass. The NMR cryoporometry technique was applied to measure pore size distribution and pore volume over a wide range of pore sizes (range from 0 to 10 000 Å) for both pretreated and enzymatically hydrolyzed biomass substrates. The results showed a clear shift in the pore size ranges (from smaller to larger) as the DAP (acid concentration 0.5% wt and temperature 160 °C) and EH time increased. In most cases, the pore volume increased with the time of treatment, which clearly suggests internal pore expansion. A linear correlation is observed between the initial rate of enzymatic hydrolysis of pretreated poplar and absolute pore volume greater than the critical pore size (51 Å) and shows the effect of residual enzyme activity on the surface of wood chips.