The Effect of Sodium Dodecyl Sulphate (SDS) on Wettability of Different Coals

Abstract

Three coals (Jincheng coal, Hancheng coal and Shan-bei coal) varying widely in coal type have been treated with anionic surfactant Sodium Dodecyl Sulphate (SDS). The effect of SDS on wettability of coals was explored by contact angles and zeta potentials characterisation techniques. Results obtained show that the addition of SDS can obviously improve the wettability of coals, and as the coal rank decreases, the wettability increases under investigation. Moreover, the wettability obviously increases with the significant decrease of particle size. The zeta potential for each coal, in the absence of surfactant, is negative, and the potential becomes more negative with the addition of SDS. Meanwhile, the FTIR spectrogram was used to test the changes of-COOH and-OH to analyze the reason for change of wettability, the results show that the wettability changes may be attributed to that the negative active ions of SDS are adsorbed on the coal surface, resulting in the increase of hydrophilic groups of the coal surface.