Various isolated soluble and insoluble lignins isolated from ammonia recycle percolation (ARP), dilute sulfuric acid, and hot-water pretreatments and two commercially available lignins (alkali and organo-solv lignin) were tested to evaluate their inhibitory effects on the enzymatic hydrolysis of cellulose. The purpose of this study was to compare the effects by adding various isolated lignins in the enzyme hydrolysis. The results showed that enzyme reaction was generally inhibited by addition of lignins. The order of lignins from most to least inhibitory effects were alkali, ARP-soluble, water-soluble, acid-soluble, ARP-insoluble, and organo-solv lignins. With 0.344 g ARP-soluble or alkali lignin/g-glucan lignin loadings, 72-h digestibilities were decreased by 16% and 20%, respectively. It was also observed that the digestibilities were decreased, as the lignin loadings increased. The hindering effect by ARP-insoluble or organosolv
lignin was not significant.
Tarkow F, Feist WC, A mechanism for improving the digestibility of lignocellulosic materials with dilute alkali and liquid ammonia, In: Hajny, G. J., Reese, E.T. Ed. Cellulases and their applications, Washington DC: American Chemical Society, 1969
NREL, Chemical Analysis and Testing Laboratory Analytical Procedures (CAT), National Renewable Energy Laboratory, Golden, Golden, CO., 2008
Chum HL, L. J. Douglas, D. A. Feinberg and H. A. Schroeder, Evaluation of pretreatments of biomass for enzymatic hydrolysis of cellulose, SERI/TP-231-2183, SERI, Golden, CO., 1985