Figure 9.

Normalized solid-state ¹³C multi-CP NMR spectra of boron lignin (red) and extractives-free white pine sawdust (black). The aromatic region is matched in the overlay since the lignin content is minimally changed during the boron lignin separation process. Relative to this, the intensity of the peaks attributed to cellulose substantially decreased in the boron lignin sample compared to that of the sawdust sample (52–66%). The same trend is true for the methoxy carbons in the boron lignin spectrum, where a 52% decrease is observed compared to the same peaks in the sawdust spectrum, providing further evidence of demethylation during separation.