C12H25−(HG)亲水基团对无烟煤润湿影响的试验和分子模拟

Effect of C12H25−(HG) hydrophilic group on the wetting of anthracite: experimental and molecular simulation

  • 摘要: 表面活性剂被广泛应用于水基降尘技术,其润湿煤尘的主控因子为亲水基团(HG)。为明确表面活性剂中HG对煤尘润湿性的影响,通过宏观润湿性能测试、量子化学计算(DFT),并结合分子模拟,探究了十二烷基型表面活性剂(C12H25−HG)常见亲水基团(\mathrmSO_4^- 、PO4H、OH、COO)在无烟煤表面润湿差异及固−液界面调控机制。结果表明:亲水基团对无烟煤的润湿效果排序为:\mathrmSO_4^- > COO > PO4H > OH;HG吸附至无烟煤表面,相对增加了疏水位点C—O含量,易形成氢键,有助于改善无烟煤润湿性;无烟煤中大部分正负电势区域都小于水分子之间的正负电势极值是无烟煤润湿性差的内在原因,HG与水分子的极值差(ΔESP)与接触角呈线性负相关,可作为评价表面活性剂润湿性能的参考指标;表面活性剂溶液−煤微观润湿界面中,根据径向分布函数(RDF)判断含不同HG的表面活性剂在无烟煤界面的吸附能力依次为:\mathrmSO_4^- > COO > OH > PO4H;相比于其他亲水基团,HG(\mathrmSO_4^- ),煤与水的相互作用能最大,氢键数目最多,水分子扩散系数提高了46.3%,吸附量增加了27.43%;HG一方面与水分子具有较强的相互作用,易形成强氢键,另一方面其吸附于煤−水界面,增强了水分子向煤表面的扩散系数,导致水分子吸附量增大,进而强化了煤尘润湿性;筛选或设计降尘剂时,可考虑引入强极性HG(\mathrmSO_4^- )以提高无烟煤润湿效率。研究结果为矿井粉尘治理中表面活性剂的应用提供理论依据和参考。

     

    Abstract: Surfactants are widely used in water-based dust suppression technology, with the main controlling factor for wetting coal dust being hydrophilic groups (HG). To clarify the impact of HG in surfactants on the wettability of coal dust, macroscopic wettability performance tests, quantum chemical calculations (DFT), and molecular simulations were used to investigate the wettability differences and solid-liquid interface regulation mechanisms of common hydrophilic groups (\mathrmSO_4^- , PO4H, OH, COO) in dodecyl surfactants (C12H25−HG) on anthracite surfaces. The results show that the wettability effect of hydrophilic groups on anthracite is ranked as follows: \mathrmSO_4^- > COO > PO4H > OH; The adsorption of HG on the anthracite surface relatively increases the content of hydrophobic sites (C—O), which easily forms hydrogen bonds and helps improve the wettability of anthracite. The intrinsic reason for the poor wettability of anthracite is that most of the positive and negative potential regions in anthracite are smaller than the positive and negative potential extremes between water molecules. The difference in extreme values between HG and water molecules (ΔESP) is linearly negatively correlated with the contact angle, which can serve as a reference index for evaluating the wettability performance of surfactants. In the micro-wetting interface of the surfactant solution-coal, the adsorption capacity of surfactants containing different HGs on the anthracite interface, as judged by the radial distribution function (RDF), is in the order: \mathrmSO_4^- > COO > OH > PO4H. Compared to other hydrophilic groups, HG (\mathrmSO_4^- ) has the greatest interaction energy between coal and water, the highest number of hydrogen bonds, an increase in the diffusion coefficient of water molecules by 46.3%, and an adsorption increase of 27.43%. HG not only has a strong interaction with water molecules, easily forming strong hydrogen bonds, but also, when adsorbed at the coal-water interface, enhances the diffusion coefficient of water molecules towards the coal surface, leading to an increase in water molecule adsorption, thereby enhancing the wettability of coal dust. When selecting or designing dust suppressants, introducing strongly polar HG (\mathrmSO_4^- ) can be considered to improve the wettability of anthracite. The research results provide theoretical basis and reference for the application of surfactants in mine dust control.

     

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