Cur-MMT复合凝胶泡沫抑制煤自燃特性

Inhibitory characteristics of curcumin-montmorillonite composite gel foam against coal spontaneous combustion

  • 摘要: 泡沫防灭火技术是采空区煤自燃防治的有效手段之一。为提升泡沫的稳定性并增强其抑制煤自燃的效果,以碳氢表面活性剂、多酚类抗氧化剂姜黄素(Cur)、无机颗粒蒙脱土(MMT)和生物质凝胶为主要原料,采用溶液共混法制备负载Cur的MMT稳泡颗粒(Cur-MMT),并进一步研发了Cur-MMT复合凝胶泡沫,以此分析了Cur-MMT复合凝胶泡沫对煤低温氧化性能及微观结构的影响特征。结果表明:Cur-MMT复合凝胶泡沫120 h内析液率为11.53%,表明泡沫结构能够保持稳定;Cur-MMT复合凝胶泡沫储能模量(G')和损耗模量(G'')交叉点对应的屈服应变较普通凝胶泡沫增加12.5%,说明Cur-MMT增强了凝胶泡沫的抗剪切变形能力,形成了更稳定的网络结构。泡沫与煤表面的接触角较纯水溶液下降56.53%,可有效润湿煤体表面,使煤样表面自由能增加10.06%。综合微观结构变化特征显示,经泡沫处理后煤样的表面分形维数DF1和空间分形维数DF2均低于原煤,孔隙表面粗糙程度和孔隙空间复杂性均有所降低;同时,处理后煤样方解石衍射峰强度增加,平均堆砌高度Lc约下降10.68%,芳香层片堆砌数量Mc下降10.81%。在性能评价中,Cur-MMT复合凝胶泡沫对煤体阻化率达到75.20%,较普通凝胶泡沫提升30.58%;煤样燃烧阶段的活化能增加19.58%,煤中甲基和亚甲基官能团峰面积降低,从而延缓了煤自燃发展进程。在机制分析中,Cur-MMT稳泡颗粒和生物质凝胶在气−液界面形成致密泡沫膜,实现对煤体表面的有效润湿和附着,并通过凝胶化作用在煤体表面形成胶体薄膜,隔绝煤体与氧气接触,抑制煤体氧化反应。研究结果为探索新型凝胶泡沫防灭火材料及其稳泡−阻化协同作用提供了新思路。

     

    Abstract: Foam fire prevention and extinguishing technology is one of the effective means for the prevention and control of coal spontaneous combustion in goafs. To improve foam stability and enhance its efficacy in inhibiting coal spontaneous combustion, curcumin (Cur)-loaded montmorillonite (MMT) foam-stabilizing particles (Cur-MMT) are prepared by the solution blending method, with hydrocarbon surfactants, the polyphenolic antioxidant curcumin (Cur), inorganic particulate montmorillonite (MMT), and biomass gel as the main raw materials. Cur-MMT composite gel foam is further developed, and the influence characteristics of Cur-MMT composite gel foam on the low-temperature oxidation performance and microstructure of coal are analyzed. The results show that the liquid drainage rate of Cur-MMT composite gel foam is 11.53% within 120 h, indicating that the foam structure can be maintained stably. The yield strain corresponding to the intersection of storage modulus (G') and loss modulus (G'') of Cur-MMT composite gel foam is increased by 12.5% compared with that of conventional gel foam, indicating that the shear deformation resistance of the gel foam is enhanced by Cur-MMT, and a more stable network structure is formed. The contact angle of the foam on the coal surface is decreased by 56.53% compared with that of pure aqueous solution; thus, the coal surface can be effectively wetted, and the surface free energy of the coal sample is increased by 10.06%. The comprehensive characteristics of microstructural changes show that the surface fractal dimension DF1 and spatial fractal dimension DF2 of foam-treated coal samples are lower than those of raw coal, and the pore surface roughness and pore spatial complexity are reduced. Meanwhile, the diffraction peak intensity of calcite for treated coal samples is increased, the average stacking height Lc is decreased by 10.68%, and the stacking number of aromatic lamellae Mc is decreased by 10.81%. In the performance evaluation, an inhibition rate of 75.20% on coal mass is achieved by Cur-MMT composite gel foam, which is 30.58% higher than that of conventional gel foam. The activation energy of coal samples in the combustion stage is increased by 19.58%, and the peak areas of methyl and methylene functional groups in coal are decreased; thus, the development process of coal spontaneous combustion is delayed. In the mechanism analysis, a dense foam film is formed at the gas-liquid interface by Cur-MMT foam-stabilizing particles and biomass gel, by which effective wetting and adhesion on the coal mass surface are achieved. Meanwhile, a colloidal film is formed on the coal mass surface through gelation, by which the contact between the coal mass and oxygen is blocked, and the oxidation reaction of the coal mass is inhibited. New insights are provided by the research results for the exploration of novel gel foam fire prevention and extinguishing materials and their synergistic foam-stabilizing and inhibition effects.

     

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