Pretreatment of Miscanthus Grass
Pretreatment studies using acid pretreatment [155-157], ammonia [156, 158], ionic liquids [159], and alkaline peroxide followed by high temperature electrolyzed water [160] have been reported for
Miscanthus giganteus.
Prairie cordgrass (Spartina pectinata) is a robust native perennial grass that can grow to about 5-8 feet tall and unbranched. The leaf blades are up to 3′ long and 1" across; they are linear, flat, green to yellowish green, and glabrous. Prairie cordgrass grows throughout the Northeast, Great Lakes and Midwest states as well as most other states in the United States. It is typically found on lower, poorly-drained soils along roadsides, ditches, streams, marshes and potholes. It also occurs in floodplains, wet meadows and back dune areas. Prairie cordgrass grows well on seasonally dry sites, tolerates alkaline conditions and high water tables, but is intolerant of prolonged flooding. Seedlings are not shade tolerant. The rapid seedling development of this species enables it to avoid frost-heaving problems on wetter soils.
It is the dominant grass of wet prairies in Illinois, and no other grass species in the state resembles it. Prairie cordgrass can be distinguished from other species by the long awns of its second glumes (about 1/3-2/3" in length) and the relative length of its first glumes, which are about the same length as the lemmas (1/3" in length). Other cord grasses lack these long awns and their first glumes are shorter than their lemmas. Prairie cordgrass is a high — yielding grass, and even unimproved genotypes of prairie cord — grass have produced nearly 10 tons of dry matter in South Dakota State University experimental trials in recent years.
Organosolv pretreatment-based fractionations are known with prairie cordgrass [161-164]; in addition to this, South Dakota State University researchers have tested a two-stage screw extruder followed by Tween-20 pretreatment on prairie cordgrass [165]. Brudecki and coworkers have studied clean fractionation as a pretreatment method for prairie cordgrass [162]. In this study they have been able to fractionate prairie cordgrass (PCG) bringing a high cellulose digestibility. During this experiment of clean fractionation (CF) processing, PCG biomass was fractionated into three main building blocks: cellulose, hemicellulose and lignin. Effects of processing factors such as time, temperature, catalyst concentration and organic solvent mixture composition were evaluated. In organosolv mixtures containing methyl isobutyl ketone (MIBK), ethanol and water in different proportions were used as solvents, whereas sulfuric acid was used as the catalyst. Additionally, Bradecki and coworkers used response surface methodology for process optimization, and the optimum conditions were established as 39 min at 154°C, with 0.69% catalyst loading in a solvent mixture with 9% MIBK. Under these optimized conditions, they were able to obtain glucose and acid insoluble lignin yields of 84%, and 87% respectively.