Differential speed two roll mill pretreatment of cellulosic materials for enzymatic hydrolysis.

Differential speed two roll milling is an effective pretreatment for increasing the susceptibility of cellulose to enzymatic hydrolysis. Using mills with three, six, and ten in. diam rolls and processing times of 10 min or less results in the following percent increases in susceptibility over untreated controls: cotton, 1100; maple chips, 1600; white pine chips, 600; newspaper, 125. In comparison, ball milling of newspaper for 24 hr gives only a 62% increase. A further advantage of the roll mill is the increased wet density of the product permitting higher slurry concentrations during hydrolysis. Important parameters of mill effectiveness are roll clearance and processing time