Production of sugar derivatives and bioethanol by two-step dilute acid pretreatment with SSF from Larix kaempferi

Lignocellulosic biomass has been attracted a lot of interests for researchers because it has several advantages such as excellent carbon fixation and possibility of alternative to fossil fuel. And pretreatment is a necessary process for producing bioethanol due to facilitating microbial activity. So, pretreatment strategies have been developed for increase of bioethanol yield. Meanwhile, liquid hydrolyzate, after pretreatment, can be utilized in numerous fields of industry through additional reaction for producing sugar derivatives. Therefore, two-step dilute acid pretreatment with simultaneous saccharification and fermentation (SSF) were operated for producing sugar derivatives and bioethanol, respectively.

The 30-year-old Larix kaempferi stem without debarking was milled to 0.5 mm size powder for pretreatment process. The moisture content of powder was less than 10%. 20 g of raw material and 140 mL of solvent were used to 1^st step dilute acid pretreatment that was carried out using a stainless steel reactor. The solvent was an aqueous solution mixing with sulfuric acid as catalyst. After 1^st step reaction, 4 mL of liquid hydrolyzate was submitted to 2^nd step treatment for producing sugar derivative. Each 1^st and 2^nd step reaction was consisted of four conditions with a variety of reaction temperature, reaction time, and sulfuric acid dosage. Meanwhile, SSF was conducted with 2 g of solid residue, which was oven-dried weight, and 50 mL of sodium acetate buffer for 96 hours in shaking incubator. The contents of sugar derivative in the raw material, solid residue, and liquid hydrolyzate were determined by bio-liquid chromatography and HPLC.