ELECTROKINETIC STUDY OF KRAFT LIGNIN

The authors studied the zeta potential of kraft lignin with or without various metal ions over a wide range of pH. They also investigated th e salt effect on surface adsorption. Kraft lignin has a negatively cha rged surface and its isoelectric point (IEP) is approximately I.O. The authors propose that the negative charges originate mainly from ioniz ation of hydroxyl groups on the kraft lignin surface. Monovalent and d ivalent ions generally adsorb indifferently on kraft lignin, but triva lent ions of aluminum do exhibit specific adsorption and shift the IEP of lignin to a higher pH.