In a previous study (Wang et al., 2015), lignin-derived NSCs that
were responsible for the turbidity of PHL were called macro-lignin
particles. As shown by Fig. S1 (Electronic Annex), the turbidity of
PHL was completely eliminated by lime treatment, making the
solution clear and transparent. The elimination of turbidity can
be explained by the reduction of lignin from 7.12 to 3.98 g/L by
lime treatment. Actually, the removal of macro-lignin impurities
is essential to the following mixed bed ion exchange treatment.
Otherwise, resin fouling will occur frequently.