Influence of different surfactants on wettability of vitrain and durain
In order to study the effects of four surfactants,APG0810,CTAC,BS-12 and SDBS on the vitrain and durain,the compositions of itrain and durain were separated,by collecting coal seam sam-ples from underground coal mine,and the wettability difference between vitrain and durain was ana-lyzed by using different techniques of contact angle measurement,wetting heat measurement,powder penetration test,water absorption nuclear magnetic resonance test.The results show that low-rank coal is weak in hydrophilicity;compared with vitrain,durain is smaller in contact angle,higher in wetting heat and in surface free energy,faster in powder penetration rate and stronger in water absorption ca-pacity,so its hydrophilicity is stronger than that of vitrain.The four different types of surfactants can significantly reduce the surface tension of water,and with the increase of the concentration of the sur-factant solution,the contact angle on the coal sample surface decreases significantly,and the change trend of the contact angle between the different types of surfactant solution and the coal sample is slightly different.The contact angle between cationic and anionic surfactants decreases exponentially with solution concentration increased.The effect of nonionic surfactants on antennae decreases as a quadratic function,and the variation trend of the curve reflectes the difference of the influencing mech-anism.The adhesion reduction factor of durain under the action of surfactant is smaller than that of vit-rain.The water in coal is mainly adsorbed water and free water,mainly adsorbed water.Compared with durain,vitrain has a higher proportion of adsorbed water and a lower proportion of free water.All the four surfactants enhance the water absorption capacity of coal.
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