SDS与AEO_(3)复配对褐煤润湿性的影响分子动力学模拟研究

Molecular dynamics simulation study on the effect of SDS and AEO_(3) complex on the wettability of lignite

为了探究阴离子与非离子表面活性剂复配对低阶煤润湿性影响的微观机理,采用分子动力学模拟的方法(MD),研究了阴离子表面活性剂(SDS)与非离子表面活性剂(AEO_(3))及二者复配体系对褐煤润湿性的影响。研究结果表明:当SDS与AEO_(3)复配时,煤/水吸附层厚度最大,为36.35×10^(-10) m,将褐煤分子层的58.83%润湿,此时水分子的扩散系数显著增加,从而提高了煤与水分子碰撞的概率,进而增强了水对褐煤的润湿性;在SDS/AEO_(3)复配体系中,褐煤与水、表面活性剂与水间的相互作用能均大于SDS与AEO_(3)单独作用体系;煤与水、表面活性剂与水之间的相互作用能均由非键能提供,非键能中静电力能占比在82.28%以上,而范德华力能贡献占比则极小,甚至会抑制表面活性剂与水间的相互作用;SDS、AEO_(3)及SDS/AEO_(3)复合情况下与水之间所产生的氢键键长差别不大,但是SDS/AEO_(3)复合情况下与水产生的氢键数量要多于SDS、AEO_(3)单独与水产生的。

In order to explore the micro-mechanism of the influence of anionic surfactant and nonionic surfactant on the wettability of low-rank coal, the molecular dynamics simulation method(MD) was used to study the influence of anionic surfactant(SDS), nonionic surfactant(AEO_(3)) and their complex system on the wettability of lignite. The results show that when SDS is compounded with AEO_(3), the thickness of coal/water adsorption layer is 36.35×10^(-10) m, which wets 58.83% of lignite molecular layer. At this time, the diffusion coefficient of water molecules increases significantly, thus increasing the probability of collision between coal and water molecules, and further enhancing the wettability of water on lignite. In SDS/AEO_(3) compound system, the interaction energy between lignite and water and between surfactant and water is greater than that of SDS and AEO_(3) alone. The interaction energy between coal and water, surfactant and water are all provided by non-bond energy, and the electrostatic energy accounts for more than 82.28% of the non-bond energy, while the contribution of Van der Waals' force energy is very small, even inhibiting the interaction between surfactant and water. There is little difference in the length of hydrogen bonds between SDS, AEO_(3) and SDS/AEO_(3), but the number of hydrogen bonds between SDS/AEO_(3) and water is more than that SDS and AEO_(3) separated produced with water.