Interaction between dispersant and coal slime added in semi-coke water slurry: An experimental and DFT study

Highlights: • SLS is more stable adsorbed on coal slime than H₂O and SH. • The adsorption of dispersant on the coal slime is accompanied by charge transfer. • Dispersants is adsorbed on coal slime by the bonding effect between O_d and H_surf. For the current situation that a large number of semi-coke powder and coal slime are difficult to be used efficiently in China. Preparation of high-performance coal-based slurry fuel is a new way to clean utilize the resources. In this article, the effect of dispersants on the performance of semi-coke water slurry containing coal slime was studied based on the experiments and density functional method (DFT). After adding 5 wt% coal slime, the slurry property is better when sodium lignin sulfonate (SLS) is selected as the dispersant, the viscosity of semi-coke water slurry with SLS as dispersant decreases from 850 mP·s to 530 mP·s, and the water-liberating rate decreases from 5.24% to 3.15%. According to DFT simulation results, the charge transfer of hydrogen atom of oxygen-containing unit structure is 0.55–0.74e when SLS is used as the dispersant. The adsorption energy between SLS and kaolinite (0 0 1) surface reaches −96.24 kJ∙mol⁻¹, while that of H₂O and sodium humate (SH) are only −1.84 kJ∙mol⁻¹ and −16.81 kJ∙mol⁻¹, respectively. The simulation results show that SLS and kaolinite have the strongest adsorption, which explains the reason why SLS is superior to SH for the preparation of semi-coke water slurry added coal slime. The research on the interaction mechanism of additives in the slurry system provides a theoretical basis for the preparation of high-performance slurry fuel and the development of new chemicals agents.