Effect of NaCl-SDS compound solution on the wettability and functional groups of coal

Abstract

In order to enhance the wetting performance of surfactants to coal dust and reduce the harm caused by coal dust, different concentration of NaCl solution was added to the anionic surfactant of Sodium Dodecyl Sulfate (SDS). The effect of NaCl-SDS compound solution on wetting coal was studied by DSA25 optical droplet morphology analysis system and Fourier transform infrared spectroscopy (FTIR). The results show that the surface tension and contact angle decrease significantly with the increase of NaCl concentration in SDS. When the concentration of NaCl is 0.9 mol/L, the surface tension and contact angle are the lowest, which are 29.41 mN/m and 29.3°, respectively. In addition, adding NaCl to SDS can change the content of functional groups in coal, in which the content of methyl (CH3) increases with the increase of NaCl concentration. The effect of CH3 content on the contact angle is the most significant, and the contact angle decreases with the increase of CH3 content. The addition of NaCl into SDS can effectively reduce the surface tension of the solution, reduce the contact angle between the solution and the coal sample, and improve the wetting effect. In this paper, a new compound solution is prepared by combining a surfactant and an inorganic salt, and the NaCl-SDS compound solution can further improve the wettability of the surfactant, and is of great significance in reducing the coal dust in the mining process of the coal mine.