Two‐step fractionation of Pinus radiata by autohydrolysis and organosolv delignification for enzymatic hydrolysis

Abstract

BACKGROUND Lignocellulosic biomass is a promising renewable feedstock to obtain fuels and chemicals. However, a suitable pretreatment is required to separate its main components and overcome its structural resistance to enzymatic hydrolysis. In this work, a sequential pretreatment composed of autohydrolysis (AH) and organosolv delignification (ORG) is used to fractionate Pinus radiata wood and improve the enzymatic hydrolysis. RESULTS The effect of three different AH pretreatment severities on the delignification degree of organosolv solid fractions was evaluated. In addition, enzymatic hydrolysis was performed to determine the efficiency of the combination of pretreatments. The results showed that a pretreated solid with high cellulose content (88%, w/w) and high delignification degree (88%) was achieved under mild conditions of AH (150 °C and 30 min) and acid‐catalyzed ORG (185 °C, 75 min, 50% (w/w) ethanol and 1% (w/w) sulfuric acid), obtaining an enzymatic hydrolysis yield of 63%. CONCLUSION This study provides the most favorable conditions to fractionate a softwood, P. radiata, employing a two‐step pretreatment based on AH followed by ORG. © 2019 Society of Chemical Industry

A review on organosolv pretreatment of softwood with a focus on enzymatic hydrolysis of cellulose

“…Non-food lignocellulosic biomass such as crop residues, energy crops and forest waste are the focus of global research in the production of second-generation biofuels and renewable biochemicals [1][2][3]. Commercial forestry based on softwood is widely spread in temperate and subtropical areas including Chile, Spain, South Africa, New Zealand and Australia [4]. In New Zealand, well-established sustainable softwood plantations are grown on 1.7 million hectares, which is about 7% of total New Zealand land area [5].…”

“…This provides an assured supply of fast-growing softwood for the pulp and paper industry and timber processing for furniture and housing. A considerable portion of waste is generated during the harvesting of the trees (such as twigs, branches, offcuts and stumps) and timber processing (such as wood chips and sawdust) that could be used as a feedstock for the production of biofuels and biochemicals [4]. One of the most promising approaches involve using enzymes to hydrolyse carbohydrate polymers to monomeric sugars and then fermenting these sugars to the various bio-based products [6].…”

Fractionation of Pinus radiata by ethanol-based organosolv process

“…The cellulose remains in the solid fraction after pretreatment, while most lignin and hemicellulose are solubilized into solvent [34]. The organosolv lignin is recovered from black liquor by precipitation, and hemicellulose-derived compounds left in the liquid phase [8,35,36]. After the separation of components achieved in organosolv process, these fractions can be used to produce value-added chemicals.…”

Combination of ethanol and Fe3O4@C‐SO3H pretreatment of Eucalyptus for glucose release via enzymatic saccharification

“…Although the cost is relatively higher than other traditional technologies, organosolv pretreatment benefits from high efficiency, as well as better fractionation of organic liquor rich in lignin part and aqueous phase rich in degraded sugars as value‐added by‐products 7,8 . Among the solvents commonly used in organosolv pretreatment, ethanol or solvents containing low molecular weight alcohols are used most frequently because alcohols can be easily obtained for a cheaper price, they are easily recovered due to their low boiling point, and they are the most biocompatible to sequential enzymatic hydrolysis or fermentation 9,10 . Aqueous ethanol (40–60%, w/w ) pulping of mixed softwoods with the catalysis of additional H 2 SO 4 produced pulps with residual lignin ranging from 6.4–27.4% (w/w).…”

“…7,8 Among the solvents commonly used in organosolv pretreatment, ethanol or solvents containing low molecular weight alcohols are used most frequently because alcohols can be easily obtained for a cheaper price, they are easily recovered due to their low boiling point, and they are the most biocompatible to sequential enzymatic hydrolysis or fermentation. 9,10 Aqueous ethanol (40-60%, w/w) pulping of mixed softwoods with the catalysis of additional H 2 SO 4 produced pulps with residual lignin ranging from 6.4-27.4% (w/w). The obtained pulp showed lessened or absent metabolic inhibitors, and resulted in an excellent performance in both sequential and simultaneous saccharification and fermentation.…”