Experimental and computational studies of polycarboxylate dispersant effect on the properties of low‐rank coal water slurries

Abstract

AbstractThe disadvantages of low‐rank coal in the preparation of coal water slurry (CWS) are well known, but the synthesis of suitable dispersants is a promising solution. Polycarboxylate dispersant (PC) is expected to be an efficient CWS dispersant due to its flexible and controllable structure. In this study, a series of binary PC dispersants were synthesized by controlling the ratio of acrylic acid (AA) to sodium styrene sulfonate (SSS), initiator fraction, and temperature, and the optimal PC was selected based on the apparent viscosity of 72# CWS at 100 s−1. The properties of 72# CWS were studied: This CWS exhibited shear‐thinning behavior, >14 static stability, and >55 wt% maximum solid loading, indicating the satisfactory performance of the optimal PC. The experimental results (including adsorption tests and zeta potential measurement) and molecular dynamics simulation showed that PC was effectively adsorbed on the surface of the coal particles by a horizontal multipoint adsorption mode, mainly through the interaction between the hydrophobic groups of the PC molecule and the hydrophobic areas of the coal particles. The hydrophilicity of the coal particles was therefore improved and the stability of their hydration layer was also enhanced, which accounted for the good static stability of 72# CWS. The amount of PC adsorption and the improved absolute zeta potential were associated with the decent properties of 72# CWS. This study is significant for promoting the molecular design of CWS dispersants based on their adsorption behavior.