Investigation on the interaction between the lipophilic structure of anionic dispersants and Shenhua non-caking coal in coal water slurry

Three anionic dispersants with different lipophilic structures and hydrophilic ends of sulfonic acid, including sodium lignin sulfonate (SLS), sulfonated acetone formaldehyde condensate (SAF) and naphthalene sulfonate formaldehyde condensate (NSF), were selected to study the effect of different lipophilic structures on the adsorption properties and dispersion mechanism. The results show that NSF and SAF are adsorbed on the surface of Shenhua non-caking coal (SNC) by single-molecular layer while SLS is adsorbed by multi-molecular layers. Through molecular dynamics simulation, the negative value of interaction energy indicates that all three dispersants can be spontaneously adsorbed on the surface of SNC. The dispersant with simple lipophilic structure has small steric hindrance during the adsorption process, which facilitate to rapidly adsorb on the coal surface with a thin layer and more adsorption sites. On the contrary, dispersants with more side chains and complex structure are adsorbed with a relatively thick layer and less adsorption sites. A dispersion mechanism of anionic dispersant on SNC surface has been proposed in this paper.