Soda pulping
Soda pulping was carried out with a 7.5% (w/v)
NaOH solution, at a solid-to-liquid ratio of 1:10, at 90
ºC for 90 min.15 Lignin was recovered from the liquor
by adding 72% (w/w) sulphuric acid until the black
liquor reached pH 2.16 The liquor was centrifuged at
4000 rpm for 15 min and the precipitated lignin was
separated and dried at 50 ºC.