Ethanol production from corn stover pretreated by electrolyzed water and a two-step pretreatment method

Pretreatment is one of the most important unit operations for ethanol production from biomass feedstocks. In this study, corn stover was used as a feedstock to examine the effectiveness of two pretreatments: electrolyzed water pretreatment and a two-step pretreatment. Electrolyzed water was employed as a catalyst to conduct one-step pretreatment of corn stover at three temperatures (165, 180 and 195°C) and three treatment times (10, 20 and 30 min). During the two-step pretreatment process, an organic alkaline solution of 1% (w/w) NaOH in 70% (w/w) ethanol was used for lignin removal in the first step, followed by a second step using hot water. No furfural or 5-hydroxymethyl furfural was detected in the hydrolysates from both pretreatment methods when the detection limit of the HPLC was 0.2 g/L. The highest glucan conversion yields were 83% obtained at 195°C for 30 min with acidic electrolyzed water and 83% by the two-step process, where the second step of the pretreatment was at 135°C for 30 min. The hydrolyzates from the two pretreatment methods showed good performance in Saccharomyces cerevisiae fermentation tests. The two new methods may provide promising alternatives for the pretreatment of biomass for ethanol production.