Effect of ionic liquid-surfactant compound solutions on the wettability and functional groups of coal

Abstract

In order to investigate the feasibility of ionic liquid-surfactant compound solutions for coal dust suppression, three ionic liquids and sodium alpha-olefin sulfonate (AOS) were selected to be compounded respectively. The compound solutions were optimized by surface tension tests and coal dust settling experiments, and FTIR and SEM tests were carried out on coal samples treated with the optimum wetting agent. The results show that when the concentration is 0.3 wt%, and the ratio of [Bmim][Cl]/AOS is 4:6, the wetting rate of compound solution is the maximum. The content of hydrophilic functional groups OH…O and C-O in the coal samples increases significantly, and the degree of benzene ring substitutions is elevated; while hydrophobic functional groups –CH, aromatic ring C = C, and benzene ring 3 substitutions (3H) are destroyed by dissolution. The micromorphology of the coal surface changes with the appearance of many cracks and pores and an increase in surface roughness. [Bmim]+ can adsorb on the drain absorption points on the coal surface by electrostatic effect, turning them into water absorption sites and attracting the surrounding AOS molecules to arrange the composite adsorption layer more closely. These results can contribute to the development of novel wetting agents with specific structures and provide theoretical guidance for the reduction of coal dust concentrations.