Adsorption of Lignosulphonates on Solids

Abstract

The adsorption of various fractionated lignosulphonates on kaolin and on titanium dioxide was studied as a function of acidity and ionic strength. The quantity adsorbed at surface saturation was found to be remarkably dependent on the pH, and to some extent on ionic strength. The adsorption was irreversible with respect to dilution for all but the lowest molecular weight fractions, but desorption could be induced by changes in the pH. This fact was employed to fractionate some lignosulphonates and may be of general utility as a method for fractionating polyelectrolytes. The data are interpreted in terms of the contributions of the electrostatic and hydrogen-bonding forces to the adsorption energy.