Dilute-Acid Pretreatment of Corn Residues and Short-Rotation Woody Crops

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

“…When side chains of acetyl group present in hemicellulose are released, acetic acid is generated. Various researchers reported a range of 1.9-7.3% acetyl group for corn stover (Balan et al, 2009;Kim & Lee, 2005b;Torget et al, 1991;Weiss et al, 2009). Acetic acid was the only byproduct found in most of the pretreated corn stover samples in the range of 0.060-0.168 g/L.…”

The chemistry involved in the steam treatment of lignocellulosic materials

“…A wide variety of chemicals have been suggested in the literature and these include sodium hydroxide [19][20][21] , sulfur dioxide [22][23][24][25][26] , aqueous ammonia 27,28 , calcium hydroxide plus calcium carbonate 27 , phosphoric acid [29][30][31] , alkaline hydrogen peroxide 32 , inorganic salts with acidic properties 33 , ammonium salts 21,33,34 , Lewis acids and organic acid anhydrides 34 , acetic acid 21,33,34 , formic acid 33 , sulfuric acid [35][36][37] , n-butylamine 38 , n-propylamine 39 and alcohols (methanol, ethanol or butanol) in the presence of an acid or alkaline catalyst 40 .…”

“…Historically, the optimal pretreatment conditions for bioconversion purposes are those in which the best substrates for hydrolysis are obtained with the least amount of soluble sugars lost to side reactions such as dehydration 15,46 . However, recovery of hemicellulose sugars in wood hydrolysates can only be maximized at lower pretreatment severities, whereas the development of substrate accessibility in steam-treated materials requires more drastic pretreatment conditions in which sugar losses are inevitable 35,36,46 . Therefore, pretreatment optimization results from a compromise between these two opposite trends unless other pretreatment variables are under consideration, such as pulp yield for paper making, lignin extractability, yield of secondary metabolites upon fermentation (e.g., organic acids, fuel ethanol, acetone and butanol, among others) and susceptibility to bioprocesses such as solid state fermentation.…”

Pretreatments to Enhance the Digestibility of Wheat Straw

“…Agricultural residue, such as corncobs and stovers, is particularly well suited to dilute acid pretreatment [51,73]. A maximum sugar yield of 541.2 mg g−1 wheat stubble was obtained by pretreatment at 2% H2SO4/90 min/121 •C followed by enzyme saccharification.…”