A comparison of various lignin-extraction methods to enhance the accessibility and ease of enzymatic hydrolysis of the cellulosic component of steam-pretreated poplar

Table 3 Solid yield, delignification and chemical composition of the four cellulose-rich fractions resulting from various two-stage pretreatments

Sample	Solid yield (%)^a	Delignification		Chemical composition (%)
Sample	Solid yield (%)^a	Extent (%)^b	Selectivity	Glu	Xyl	Ara	Gal	Man	Lignin
Raw poplar	–	–	–	48.9	14.6	0.4	0.6	2.9	27.5
SP2	–	–	–	63.6	4.9	0.0	0.1	1.2	27.4
DES-SP2	82.6	52.4	5.2	72.9	4.3	0.0	0.0	0.0	15.8
Organosolv-SP2	66.3	63.2	4.4	75.1	2.2	0.0	0.0	2.4	15.2
Soda/AQ-SP2	72.5	54.5	4.2	70.5	2.3	0.0	0.0	2.4	17.2
Hydrotrope-SP2	84.5	40.5	4.4	69.5	3.3	0.0	0.0	2.3	19.3

–, cannot be determined
^a Based on the dry weight of the substrate resulted from steam pretreatment at 190 °C for 9.9 min (SP2)
^b Based on the lignin content in SP2 substrate

ISSN: 2731-3654