复配表面活性剂协同润湿无烟煤微观机制研究

    Study on microscopic mechanism of synergistic wetting of anthracite by compound surfactants

    • 摘要: 为探究非离子型、阴离子型表面活性剂复配对煤的协同润湿效应及微观机制,以贵州黔北煤田无烟煤为研究对象,通过沉降试验优选非离子型、阴离子型表面活性剂及二者复配最佳体积比,利用接触角试验验证复配溶液的协同润湿作用,并运用分子动力学模拟从平衡吸附构型、径向分布函数、相互作用能、相对浓度分布及扩散系数等角度揭示非离子型、阴离子型表面活性剂的协同润湿机制。沉降试验结果表明,非离子表面活性剂脂肪醇聚氧乙烯醚(JFC−U)和阴离子表面活性剂十二烷基苯磺酸钠(SDBS)的最佳质量分数均为0.15%;两者按体积比1∶2复配时,煤样沉降速度达最大值,协同润湿效果最佳。接触角试验显示,JFC−U和SDBS复配溶液与煤样的接触角为25.3°,较单体溶液均减小,验证了复配溶液的协同润湿效果。分子动力学模拟表明,复配系统中JFC−U分子嵌入SDBS亲水基团簇空隙,使亲水基层更致密;径向分布函数在0.375 nm处出现特征峰,表明SDBS苯环与煤芳香结构存在π−π堆叠作用,增强了表面活性剂在煤表面的吸附稳定性。相较于JFC−U、SDBS单体系统,复配系统中煤−水相互作用能绝对值明显增大,水分子扩散系数降低,氢键数量显著增加,表明JFC−U 与 SDBS 的共同作用可提高表面活性剂分子层与水分子形成氢键的能力,增强煤与水的相互作用,抑制水分子的扩散,并提高煤表面对水分子的吸附聚集能力。

       

      Abstract: To investigate the synergistic wetting effect and microscopic mechanism of nonionic and anionic surfactant compounding on coal, the anthracite from Qianbei Coalfield of Guizhou Province was taken as the research object. Nonionic and anionic surfactants as well as their optimal volume ratio for compounding were optimized through sedimentation experiments. The synergistic wetting effect of the compound solution was verified by contact angle tests, and molecular dynamics simulation was employed to reveal the synergistic wetting mechanism of nonionic and anionic surfactants from the perspectives of equilibrium adsorption configuration, radial distribution function, interaction energy, relative concentration distribution and diffusion coefficient. The sedimentation experimental results show that the optimal mass fraction for both the nonionic surfactant fatty alcohol polyoxyethylene ether (JFC-U) and the anionic surfactant sodium dodecylbenzene sulfonate (SDBS) is 0.15%. When the two are compounded at a volume ratio of 1:2, the sedimentation rate of coal samples reaches the maximum, with the best synergistic wetting effect. Contact angle tests indicate that the contact angle between the JFC-U and SDBS compound solution and coal samples is 25.3°, which is lower than that of single-component solutions, verifying the synergistic wetting effect of the compound solution. Molecular dynamics simulations show that JFC-U molecules are embedded in the gaps of SDBS hydrophilic group clusters in the compound system, making the hydrophilic base layer denser. A characteristic peak of the radial distribution function appears at 0.375 nm, indicating the existence of π–π stacking between the benzene rings of SDBS and the aromatic structure of coal, which enhances the adsorption stability of surfactants on the coal surface. Compared with the single-component JFC-U and SDBS systems, the absolute value of coal-water interaction energy in the compound system increases significantly, the diffusion coefficient of water molecules decreases, and the number of hydrogen bonds rises remarkably. This demonstrates that the combined action of JFC-U and SDBS can improve the ability of the surfactant molecular layer to form hydrogen bonds with water molecules, strengthen the interaction between coal and water, suppress the diffusion of water molecules, and enhance the adsorption and aggregation capacity of the coal surface for water molecules.

       

    /

    返回文章
    返回