Experimental investigation of coal dust wetting ability of anionic surfactants with different structures

Abstract

Abstract To better understand the coal dust wetting ability of anionic surfactants with different structures, sodium dodecyl sulfate (SDS), sodium dodecyl sulfonate (SDDS), and sodium dodecyl benzene sulfonate (SDBS) were selected. The surface tension, wetting time, and infrared spectra of coal dust were tested. The hydrophilic-lipophilic balance (HLB) values of the surfactants were calculated. Results showed that the decrease in the surface tension could shorten the wetting time at low surfactant concentrations. But the decrease in the wetting time was no longer related to the constant surface tension that was lower than 45 mN/m. The adsorption density depends on the hydrophobic interactions and electrostatic repulsions between the surfactant molecules and the coal dust. During the dynamic immersion process, the surfactants with high HLB values could bring the coal dust into the bulk solution rapidly. The wetting time of coal dust for SDBS with a high adsorption density and low HLB or SDS with a small adsorption density and high HLB was relatively longer. The adsorption density and HLB value of SDDS were intermediate between those of SDS and SDBS. Under the combined action of these two factors, the wetting time of SDDS was shorter than those of SDS and SDBS.