Synthesis, adsorption and dispersion of a dispersant based on starch for coal–water slurry

A comb-type molecular dispersant based on starch for coal–water slurry (CWS) was synthesized from the copolymerization of starch, acrylic acid and styrene (SAS). The structure of SAS was characterized via Fourier transform infrared (FTIR) and gel permeation chromatography (GPC). Apparent viscosity and static stability of CWS were respectively measured by rheometer and water separating test. The interaction of the dispersant with coal particles was analyzed using zeta potential of CWS, contact angle of coal surface, scanning electron microscope (SEM) and adsorption isotherm of the dispersant on the interface of coal and water. The results show that the viscosity of CWS with 65.0 wt% coal and 0.5 wt% SAS dispersant is 862 mPa s under 100 s−1. Besides, the reducing viscosity and static stability of CWS with SAS is better than commercial naphthalene sulfonate (NSA) and natural polymeric dispersant sodium lignosulfonate (MLS). On the surface of Binchang coal, the adsorption quantity of SAS is larger than that of NSA and MSL. The molecule of SAS dispersant has hydrophobic groups connecting to the surface of coal and hydrophilic groups connecting to water, which results in uniform dispersion of coal particles in water.