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Liquor re-use strategy in lignocellulosic biomass fractionation with ethanol-water mixtures

Vergara, Priscilla, García-Ochoa, Félix, Ladero, Miguel, Gutiérrez, Soledad, Villar, Juan C.
Bioresource technology 2019 v.280 pp. 396-403
acetic acid, biomass, cellulose, energy, enzymatic hydrolysis, fractionation, glucose, hemicellulose, hydrolysates, lignin, lignocellulose
Liquor recycle in lignocellulosic biomass fractionation with ethanol-water has been studied. Runs have been carried out in a 6 L tank reactor with liquor recirculation. The liquors obtained in six successive fractioning operations have been analyzed together with the solid phase remnant. Experimental results revealed that the number of re-uses reduces solids recovery (from 52.2 to 42.6%) and cellulose recovery (from 28.1 to 23.3%) with minor or no effect on the hemicelluloses and lignin removal. The more remarkable effect is an increase of the glucose yield (from 76.7 to 95.3% after enzymatic hydrolysis during 72 h). The accumulation of acetic acid in the spent liquors (until 1.3 g/L) seems to be responsible of the higher enzymatic hydrolysis yield, from 76.3 (first use) to 87.7% (fifth re-use). Liquor re-use is effective to improve the sustainability of the pre-treatment obtaining a cellulose-rich solid easy to hydrolysate to sugars reducing energy consumption.