Two-Stage Fractionation of Corn Stover Using Aqueous Ammonia and Hot Water

Abstract

Hot water and aqueous ammonia fractionation of corn stover were used to separate hemicellulose and lignin and improve enzymatic digestibility of cellulose. A two-stage approach was used: The first stage was designed to recover soluble lignin using aqueous ammonia at low temperature, while the second stage was designed to recover xylan using hot water at high temperature. Specifically, the first stage employed a batch reaction using 15 wt.% ammonia at 60 °C, in a 1:10 solid:liquid ratio for 8 h, while the second stage employed a percolation reaction using hot water, 190-210 °C, at a 20 ml/min flow rate for 10 min. After fractionation, the remaining solids were nearly pure cellulose. The two-stage fractionation process achieved 68% lignin purity with 47% lignin recovery in the first stage, and 78% xylan purity, with 65% xylan recovery in the second stage. Two-stage treatment enhanced the enzymatic hydrolysis of remaining cellulose to 96% with 15 FPU/g of glucan using commercial cellulase enzymes. Enzyme hydrolyses were nearly completed within 12-24 h with the remaining solids fraction.

Recovery of Xylo-oligomer and Lignin Liquors from Rice Straw by Two 2-step Processes Using Aqueous Ammonia Followed by Hot-water or Sulfuric Acid

“…As shown in Table 2 and Table 3, both two-step treatments were found to be effective for lignin and xylan removal. It also confirmed previous finding that lignin generally hinders enzymatic reaction of cellulose [24][25][26].…”

Organosolv fractionating pre‐treatment of lignocellulosic biomass for efficient enzymatic saccharification: chemistry, kinetics, and substrate structures

“…Sequential dilute acid and alkali pre‐treatment of corn stover removed 85.9–89.4% of lignin and hydrolyzed 74.6–77.3% of xylan, resulting in an overall glucose and xylose yields of 89.1–97.9% and 71.0–75.9%, respectively . Using a two‐stage pre‐treatment of corn stover with aqueous ammonia and hot water to remove lignin and hemicellulose, respectively, Yoo et al obtained a nearly‐pure cellulose and 68% lignin purity with 47% lignin recovery in the first stage, and 78% xylan purity with 65% xylan recovery in the second stage. The pre‐treated cellulose solid showed an enzymatic cellulose conversion of 96%.…”

Pretreatment and fractionation of lignocellulosic biomass for production of biofuel and value-added products

“…The articles in chapters 2-6 have been published, or are in review, in peer-review journals. Chapter 2 is an article entitled "Two-stage fractionation of corn stover using aqueous ammonia and hotwater" published in the journal of Applied Biochemistry and Biotechnology (Yoo et al, 2011).…”