Optimization of switchgrass and extruder parameters for enzymatic hydrolysis using response surface methodology

Application of Response Surface Methodology to Optimize Alkali Concentration, Corn Stover Particle Size, and Extruder Parameters for Maximum Sugar Recovery

“…No glycerol was found in any of the pretreatment combinations in contrary to the results reported by Karunanithy and Muthukumarappan (Karunanithy & Muthukumarappan, 2010c, 2011a, 2011b, 2011c, 2010a, 2010b.In addition, no furfural and HMF were found in any of the pretreated corn stover samples. The possible reason could be short residence time and no acidic conditions during pretreatment as compared most of the pretreatment methods listed in the table.…”

“…The proposed quadratic models in terms of actual variables are given below for glucose (Y G ), xylose (Y X ), and combined sugar (Y C ) recovery, where X 1 , X 2 , X 3 , and X 4 represent barrel temperature (°C), screw speed (rpm), alkali concentration (% w/v), and particle size (mm) of corn stover, respectively. Similar equations were reported for acid hydrolysis of sugarcane bagasse (Neureiter et al, 2002), oil palm empty fruit bunch (Rahman et al, 2007), eucalyptus (Canettieri et al, 2007), for concentrated acid pretreatment of pine wood (Miller & Hester, 2007 ), acid catalyzed fractionation and enzymatic hydrolysis of flax shives (Kim & Mazza, 2008), hot-compressed water pretreatment of Japanese beech hydrolysis (Xin & Saka, 2008), and extrusion pretreatment of corn stover (Karunanithy & Muthukumarappan, 2011a). Those equations predict the responses well with high R 2 and low probability values.…”

“…An extruder has the ability to provide high shear, rapid heat transfer, effective and rapid mixing in a short residence time, as well as adaptability to many different processes -all in a continuous process. A few extrusion pretreatments (Dale et al, 1999;de Virje et al, 2002;Karunanithy et al, 2008;Karunanithy & Muthukumarappan, 2010a, 2010b, 2010c, 2011a, 2011b, 2011c Lee et al, 2009;Muthukumarappan & Julson, 2007 ) showed a significant improvement on sugar recovery from corn stover, switchgrass, miscanthus, prairie cord grass, big bluestem, and Douglas fir through enzymatic hydrolysis. Potential fermentation inhibitors such as furfural and HMF were not reported in any of the above studies.…”

Optimization of Enzymatic Hydrolysis of Corn Stover for Improved Ethanol Production

“…The pretreatment of CS in a single screw extruder prior to enzymatic hydrolysis was shown to be effective in fractionating the hemicellulose and lignin components with a minimal yield loss (Karunanithy and Muthukumarappan, 2011). Our work confirmed previous findings that extrusion did not significantly change the cellulose, hemicellulose and lignin content of CS (Table 2).…”

Characterization of Biobased Polyurethane Foams Employing Lignin Fractionated from Microwave Liquefied Switchgrass

“…It has been used over other crops for conversion to bioenergy within the United States and was identified by the US Department of Energy as a model herbaceous energy crop [24]. Nowadays, fast pyrolysis and enzymatic hydrolysis have been used as common strategy for energy conversion employing switchgrass [25,26]. Recent research on alkaline pretreatment of switchgrass for lignin removal and sugar retentions for economic valuable cellulosic ethanol production was reported by Karp et al [27].…”