十二烷基型表面活性剂亲水基团对含瓦斯煤润湿的调控行为及机制

Regulation behavior and mechanism of hydrophilic groups of dodecyl surfactants on wetting of gas-bearing coal

  • 摘要: 瓦斯和煤尘是制约煤矿安全生产、危害矿工生命健康的两大杀手。煤层注水被广泛用于煤尘防治和瓦斯治理,高瓦斯煤层中瓦斯严重干扰着水分对煤体的润湿,导致含瓦斯煤润湿效果差。十二烷基型表面活性剂(C12H25−HG)常被用于不含瓦斯煤的增润研究,C12H25−HG常见的亲水基团(HG)有—OH、—COOH及—SO3H,但其对含瓦斯煤润湿的调控行为及机制不清楚。采用试验及分子动力学模拟的方法展开了研究,C12H25−HG溶液与瓦斯之间的表面张力、与含瓦斯煤之间的接触角、界面能,C12H25−HG溶液及纯水浸润煤样后官能团的演化规律,疏水位点与水分子的电势差表明,—OH、—COOH及—SO3H亲水基团对含瓦斯煤润湿的调控效果逐渐增加;在表面活性剂溶液−含瓦斯煤微观分子结构模型中,—OH、—COOH及—SO3H亲水基团分别与水分子中氧原子之间的相互作用逐渐增强,其径向分布函数及配位数逐渐增加;—OH、—COOH及—SO3H亲水基团的存在,使得疏水基团与煤分子之间的径向分布函数及配位数呈现出增加的趋势;对于含有—OH、—COOH及—SO3H基团的C12H25−HG溶液,水分子的吸附程度逐渐增强、扩散系数逐渐降低,而聚集程度逐渐提高,甲烷分子被置换的程度逐渐增加、甲烷分子扩散系数逐渐增加;水中引入—SO3H亲水基团有助于提升含瓦斯煤的润湿效果。研究结果为高效筛选适用于煤矿瓦斯灾害防治的表面活性剂及揭示煤层注入表面活性水治理瓦斯的机制提供理论指导。

     

    Abstract: Gas and coal dust are the two major killers that restrict coal mine safety production and endanger the lives and health of miners. Coal seam water injection was widely used for coal dust prevention and gas control. However, in coal seams with high gas content interferes with the wetting of coal by moisture, resulting in poor wetting effect of gas-bearing coal. Dodecyl surfactants (C12H25−HG) were frequently utilized in studies aimed at enhancing the wetting of non-gas-containing coal. Typical hydrophilic groups (HG) within these surfactants include —OH, —COOH, and —SO3H. However, the regulatory behavior and mechanisms of these groups concerning the wetting of gas-containing coal remain unclear. This paper conducted research using experimental and molecular dynamics simulation methods. The surface tension between C12H25−HG solution and gas, the contact angle between C12H25−HG solution and gas-containing coal, the interfacial energy, the evolution of functional groups after C12H25−HG solution and pure water infiltration of coal samples, and the potential difference between hydrophobic sites and water molecules showed that the control effect of —OH, —COOH, and —SO3H hydrophilic groups on the wetting of gas-bearing coal gradually increased. In the micro models of surfactant solutions and gas-bearing coal, the interactions between —OH, —COOH, and —SO3H hydrophilic groups and oxygen atoms in water molecules are enhanced, and their radial distribution functions and coordination numbers gradually increase. The presence of hydrophilic groups such as —OH, —COOH, and —SO3H results in an increasing radial distribution function and coordination number between hydrophobic groups and coal molecules. For dodecyl surfactant solutions containing —OH, —COOH, and —SO3H groups, the adsorption degree of water molecules gradually increases and the diffusion coefficient gradually decreases, while the aggregation degree gradually increases. The degree of methane molecule displacement gradually increases and the diffusion coefficient gradually increases. The introduction of - SO3H hydrophilic groups into the solution helps to improve the wetting performance of gas-bearing coal. The research results provide theoretical guidance for efficient screening of surfactants suitable for coal mine gas control and revealing the mechanism of injecting surface active water into coal seams for gas control.

     

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