Oxidative lime pretreatment of high-lignin biomass: poplar wood and newspaper.
Lime (Ca[OH]2) and oxygen (O2) were used to enhance the enzymatic digestibility of two kinds of high-lignin biomass: poplar wood and newspaper. The recommended pretreatment conditions for poplar wood are 150 degrees C, 6 h, 0.1 g of Ca(OH)2/g of dry biomass, 9 mL of water/g of dry biomass, 14.0 bar absolute oxygen, and a particle size of -10 mesh. Under these conditions, the 3-d reducing sugar yield of poplar wood using a cellulase loading of 5 filter paper units (FPU)/g of raw dry biomass increased from 62 to 565 mg of eq. glucose/g of raw dry biomass, and the 3-d total sugar (glucose + xylose) conversion increased from 6 to 77% of raw total sugars. At high cellulase loadings (e.g., 75 FPU/g of raw dry biomass), the 3-d total sugar conversion reached 97%. In a trial run with newspaper, using conditions of 140 degrees C, 3 h, 0.3 g of Ca(OH)2/g of dry biomass, 16 mL of water/g of dry biomass, and 7.1 bar absolute oxygen, the 3-d reducing sugar yield using a cellulase loading of 5 FPU/g of raw dry biomass increased from 240 to 565 mg of eq. glucose/g of raw dry biomass. A material balance study on poplar wood shows that oxidative lime pretreatment solubilized 38% of total biomass, including 78% of lignin and 49% of xylan; no glucan was removed. Ash increased because calcium was incorporated into biomass during the pretreatment. After oxidative lime pretreatment, about 21% of added lime could be recovered by CO2 carbonation.
Chang
V S
VS
Department of Chemical Engineering, Texas A&M University, College Station 77843-3122, USA.
Nagwani
M
M
Kim
C H
CH
Holtzapple
M T
MT
D018533:Biomass; D017610:Calcium Compounds; D002241:Carbohydrates / Q000032:analysis; D002480:Cellulase; D002616:Chemical Engineering; D003246:Conservation of Energy Resources; D004736:Energy-Generating Resources; D006868:Hydrolysis; D008031:Lignin; D010084:Oxidation-Reduction; D010087:Oxides; D010209:Paper; D014934:Wood
D017610:Calcium Compounds; D002241:Carbohydrates; D010087:Oxides; D008031:Lignin; C016538:lime; D002480:Cellulase