Influence of Fine Grinding on the Hydrolysis of Cellulosic Materials—Acid Vs. Enzymatic

Abstract

The relative influence of ball milling for various time periods on the course of enzymatic and dilute acid hydrolysis was investigated. The response of enzymatic hydrolysis to the extent of milling was quite dramatic. Cotton linters pulp was totally hydrolyzed in 10 days with 60 min of milling. The carbohydrates of red oak were 93% converted to sugar in the same time after 240 min of milling. It appears that, with sufficient milling, the carbohydrates of the three lignocelluloses investigated can be made almost totally accessible to enzymatic hydrolysis. Vibratory milling also yields substantial increases in the rates of dilute acid hydrolysis of all four substrates, nearly nine-fold for the cotton linters pulp and about five-fold for the three lignocelluloses. Thus vibratory milling represents an experimentally effective pretreatment.ignin and cellulose crystallinity are major deterrents to the chemical, enzymatic, and microbiological conversion of lignocellulosic residues to useful products. Lignin restricts enzymatic and microbiological access to the cellulose. Crystallinity restricts the rate of all three modes of attack on the cellulose. Thus if we are ever to make full use of the carbohydrate values contained in the many millions of tons of currently unused lignocellulosics generated in this country each year, some form of pretreatment must be employed to alter the fine structure of cellulose as well as disrupt or open up the lignin-carbohydrate complex. 1 Maintained at Madison, WI, in cooperation with the University of Wisconsin. This chapter not subject to U.S.

Effect of mild torrefaction on pulverization of Norway spruce (Picea abies) by oscillatory ball milling: particle morphology and cellulose crystallinity

“…Vibration mills cause a drastic decrease in cellulose crystallinity in the particles (Schwanninger et al 2004;Kobayashi et al 2007Kobayashi et al , 2008Agarwal et al 2013;Karinkanta et al 2013a). This kind of milling enhances the reaction rate of wood hydrolysis (Pew and Weyna 1962;Millett et al 1976Millett et al , 1979 and facilitates mild lignin isolation by solution (Sarkanen and Ludwig 1971;Bland and Menshun 1973;Maurer and Fengel 1992;Guerra et al 2006;Li et al 2011;Qu et al 2012). It is also known that different ball mills (such as planetary and tumbling ball mills) destruct heavily the fibrous structure of wood (Fukuzawa et al 1982;Mikushina et al 2003) and cause a drastic decrease in the cellulose crystallinity (Gharpuray et al 1983;Rivers and Emert 1987;Stubičar et al 1998;Da Silva et al 2010).…”

Characterization of changes induced by ageing to the microstructure of pure cellulose paper by use of a gravimetric water vapour adsorption technique

“…The samples were ground by a cutting mill to pass through a 500-mm screen (ball milling is known to reduce the crystallinity of cellulose; Segal et al 1959;Millett et al 1979;Klemm et al1998, p. 104). A Siemens D5000 diffractometer was used (k = 1.5406 Å , V = 40 KV, I = 30 mA), and the rotation speeds of the detector and the sample holder were adjusted so that they moved from a 2h angle of 10-278 in 14 min.…”

An examination of biorefining processes, catalysts and challenges

“…There are various techniques used for the comminution of biomass, including dry, wet and vibratory ball milling [25,26] and compression milling [27]. However, where the smallest particle sizes are required, as in some dilute acid pre-treatment processes and in entrained flow gasifiers, the energy costs required may account for up to a third of the total energy demand of the biorefinery [28].…”