Abstract: To improve the effect of water injection in coal seams,and effectively prevent gas disasters in mines,influences of non-cationic surfactants on the wetting of coal were researched.A JCY contact angle tester and a BZY surface tension tester were used to determine the contact angles and surface tensions of solutions of sodium dodecyl benzene sulfonate (SDBS),sodium dodecyl sulfate (SDS),fatty alcohol polyoxyethylene ether (AEO),and (TX-100) having different mass concentrations.The solution spread coefficient,critical surface tension,adhesion tension,adhesion work,and surface free energy were calculated.The influences of 4 kinds of surfactants on the wettability of coal were analyzed.The results show that the surface tension and contact angle of the four non-cationic surfactant solutions have a negative first-order exponential function relationship with the solution mass concentration.The spreading coefficient is a power function of the surfactant solution mass concentration; both the adhesion work,and adhesion tension are a negative power function of the solution mass concentration.The surface free energy has a negative linear relationship with the solution mass concentration.The critical surface tension,adhesion tension,adhesion work,and surface free energy of SDBS and SDS solutions are less than those of AEO and TX-100 solutions,but the spreading coefficient larger than those of AEO and TX-100 solutions,which indicates that SDBS and SDS can improve wettability of coal better than AEO and TX-100,and the effect of water injection on coal seams is obvious.

Key words: non-cation, surfactant, wettability, surface tension, contact angle