The effect of mix-milling with P₂O₅ on cellulose physicochemical properties responsible for increased glucose yield

Breaking the recalcitrant structure of native crystalline cellulose is an energy demanding rate liming step in the production of glucose from cellulosic biomass. Mix-milling of lignocellulosic substrates (with P₂O₅) dramatically increased glucose yield. In this work, the changes of physicochemical characteristics (morphology, structure, degree of polymerization (DP), solubility) of cellulose during mix-milling (with P₂O₅) are correlated with glucose yield in the subsequent chemical hydrolysis process. The mix-milling enables highly efficient breakdown of cellulose I crystalline to smaller amorphous particles with low DP, which is recrystallized into cellulose II structure after water-wetting. As a result, the mix-milled cellulose (MMC) shows higher hydrolysis reactivity than that of single-milled cellulose (SMC). The results showed that small particle size, low DP, higher solubility and cellulose II content are correlated with the hydrolysis reactivity of cellulose.