A sulfonated lignin-based polymer

SBAL

was prepared by sulfomethylation

etherification and polycondensation reaction using alkali lignin from the alkaline pulping spent liquor of bamboo as main material. TEM and 1H-NMR results showed that the structure of SBAL was loose spherical

the center of which was the hydrophobic skeletons of lignin

the long side chains with sulfonic and carboxyl groups were distributed on its surface. GPC and potentiometric titration results showed that the Mw of SBAL reached 24880 Da

7.38 times of the alkali lignin

and the sulfonic group content was 2.70 mmol穏-1. The adsorption properties and the dispersion efficiencies of SBAL were investigated by means of isothermal adsorption

XPS

zeta potential and rheological experiments. At pH 3~12

the SBAL as dispersant can remarkably reduce the viscosity of alumina slurry. The sulfonic

carboxyl and phenolic hydroxyl groups of SBAL are ionized gradually as pH increasing

which makes the SBAL molecule chains spread well in the alkali condition. With the increase of pH

the adsorption amount of SBAL on alumina particles decreases and the adsorption configuration changes from compact to loose. When pH is lower than isoelectric point of alumina

the main adsorption force between SBAL and alumina particle is electrostatic adsorption

however

when pH is more than isoelectric point

non-static specific adsorption dominates the main force. When the dosage of SBAL is less than the critical dosage (0.5wt%)

SBAL generates an electrostatic repulsion between particles by monolayer adsorption on alumina surface

moreover

when the SBAL dosage is more than the critical one

SBAL may adsorb on alumina particles in the form of aggregation and improve the steric hindrance action.