Properties of sodium lignosulfonate as dispersant of coal water slurry

Five purified sodium lignosulfonate (SL) samples with different molecular weights were prepared by fractionation using ultrafiltration and dialysis. The effect of SL on the apparent viscosity of coal-water slurry (CWS) was investigated. The adsorption behavior of the dispersants on coal-water interface has much greater effect on the viscosity of coal water slurry. The higher adsorption amount of SL on coal surface and compact adsorption film help reduce the viscosity of CWS, and that the zeta potential of coal surface is also an important factor, which is influenced by the sulfonic and carboxyl group contents of lignosulfonate. The SL with its molecular weight ranging from 10000 to 30000 has both a higher adsorbed amount and zeta potential on coal surface and the best effect on reducing the viscosity of the coal-water slurry.