Synthesis and performance of a comblike amphoteric polycarboxylate dispersant for coal-water slurry

A novel comblike polymer, amphoteric polycarboxylic (AmPC), was designed as a dispersant for coal-water slurry (CWS) and synthesized in aqueous solution from the copolymerization of macromonomer polyethylene glycol-acrylate monoester (PA), sodium p-styrene sulfonate (SSS) and cationic comonomer methacrylatoethyl trimethyl ammonium chloride (DMC). PA was prepared by esterifying with polyethylene glycol (PEG) and acrylic acid (AA) in our laboratory. And then, the molecule structure of amphoteric polycarboxylic dispersant was characterized by means of Fourier transformer infrared (FTIR). Besides, the dispersant was applied in Shenfu coal slurry. By examining the apparent viscosity of the coal slurry using rheometer, the effects of the mole ratio of SSS and PA, amount of cationic monomer DMC, initiator concentration and reaction temperature on the AmPC dispersant performance were discussed. The wetting property of AmPC dispersant on the coal surface and Zeta potential of the CWS with AmPC dispersant was measured. The result shows that the apparent viscosity decrease of amphoteric polycarboxylic dispersant is better than the dispersant in stock which does not have cationic monomer when the dosage of DMC is 5.0 wt%. It has been proved that the amphoteric polycarboxylic dispersion agent is suitable for Shenfu coal slurry. When the dosage of AmPC dispersant is up to 0.3 wt%, the highest concentration of coal-slurry can reach 65.0 wt%. AmPC dispersant with both anionic group and cationic group will provide the better anchoring action with the coal via the adsorption of ion pair. It possesses not only dramatic wetting on coal but also stable steric hindrance so as to disperse coal particles in water. (C) 2012 Elsevier B.V. All rights reserved.