(374w) Alkaline Pretreatment of Lignocellulosic Biomass with Additives

Pretreatment of different lignocellulosic biomass, popolar, softwood-based waste newsprint, and corn stover was investigated. Pretreatment was done by soaking in aqueous ammonia, aqueous sodium hydroxide solution, and lime with and without additives. Benzethonium chloride and polyethylene glycol (PEG) were used as additives. Alkaline pretreatment without additives resulted delignification in the range of 20 to 50%. Addition of PEG increased delignification and the enzymatic digestibility of the treated biomass. Addition of benzethonium chloride, however, had a negative effects on delignification due to the benzethonium cation binding with lignin during alkaline pretreatment. The enzymatic digestibility of pretreated biomass increased by 10% to 20% by addition of benzethonium chloride. It is speculated that the lignin surface is modified by benzethonium cation such that it prevents non-productive binding with cellulase enzyme. The carbohydrates retention in the solid after pretreatment also increased when additives were used. This is a significant economic benefit since it eliminates the need of detoxification of hemicellulose sugars. For various pretreated lignocellulosic biomass feedstocks, the overall enzymatic digestibilities were in the range of 60 to 70% with 15 FPU loading of Spezyme CP. In order to increase the enzymatic digestibility polyvinyl alcohol (PVA) or PEG was added during enzymatic hydrolysis. Addition of PVA or PEG, the enzymatic hydrolysis yield has increased by 10% to 20% for the substrates pretreated without additives. However, the increase was only by 5% for the substrates pretreated with additives.