BioChem - DOS

Optimal Pretreatment of Eucalyptus globulus by Hydrothermolysis and Alkaline Extraction for Microbial Production of Ethanol and Xylitol

Industrial & engineering chemistry research

Castro, Jean F.; Parra, Carolina; Yá ñ ez-S, Mauricio; Rojas, Jonathan; Teixeira Mendonç a, Regis; Baeza, Jaime; Freer, Juanita

<P>Fractionation of Eucalyptus globulus wood chips is mandatory for developing a biorefinery process. In order to achieve this, products released from hydrothermolysis pretreatment were studied within the severity (log <I>R</I><SUB>0</SUB>) range 3.3&ndash;4.5. The highest solubilized xylose yield was 56% (DWB) at log <I>R</I><SUB>0</SUB> 3.9. Values higher than log <I>R</I><SUB>0</SUB> 4.1 have led to high xylose dehydration rates. Detoxification steps applied to the liquor removed acetic acid (55%), furfural (94%), and hydroxymethylfurfural (HMF) (31%). Fermentation of liquor with Candida guilliermondii resulted in a xylitol yield of 0.37 g of xylitol produced per gram of xylose consumed (equivalent to 71% of the control with pure xylose). Pulp-1 (from hydrothermolysis pretreatment) was further pretreated with NaOH for lignin removal (obtaining Pulp-2). Cellulose composition in Pulp-1 and Pulp-2 remains almost unaltered; lignin content in Pulp-2 was 50% lower than in Pulp-1. Simultaneous saccharification and fermentation (SSF) experiments for both pulps reached similar ethanol yields of 0.76 and 0.70 g of ethanol produced per gram of ethanol potentially produced from wood, respectively. Recovery of hemicellulose at the beginning of the process is a key step for getting pulps with high cellulose composition available for developing a biorefinery process of E. globulus.</P>

2013

American Chemical Society

0888-5885

1520-5045

52

16

pp.5713-5720

10.1021/ie301859x

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