Adding value to Alfa grass (Stipa tenacissima L.) soda lignin as phenolic resins 1. Lignin characterization

Soda lignin from black liquors of Alfa grass was precipitated with hydrochloric acid at pH 2 and 4.5, and with sulfuric acid at pH 4.5. The molecular structures of the lignins were analyzed for the first time. The phenolic structures were studied using UV-visible spectroscopy and 31P-NMR spectrometry. The lignin fragments were also analyzed by size exclusion chromatography and β-O-4 bond content was determined by thioacidolysis. The total...