Table 1.

Contents and locations of various hydroxyl groups in these five lignins quantified by ³¹P NMR technique.

–OH Content (mmol g−1)	DES Lignin	Organosolv Lignin	Soda/AQ Lignin	Hydrotrope Lignin	Kraft Lignin
Aliphatic -OH	2.40	1.04	1.17	2.00	1.98
Syringyl phenolic -OH	1.31	2.03	1.92	1.63	1.02
Guaiacyl phenolic -OH	0.90	1.20	1.31	1.02	2.11
p-hydroxyphenyl -OH	0.23	0.15	0.02	0.41	0.05
Carboxylic acid -OH	0.18	0.09	0.87	0.32	0.37
Total phenolic -OH	2.44	3.37	3.25	3.06	3.18