Skripkina Tatiana, Ulihin Artem, Bychkov Aleksey, Mamylov Sergey, Podgorbunskikh Ekaterina, Lomovskiy Igor, Lomovsky Oleg
Institute of Solid State Chemistry and Mechanochemistry SB RAS Novosibirsk 630128 Russia
RSC Adv. 2020 Jun 3;10(36):21108-21114. doi: 10.1039/d0ra03131c. eCollection 2020 Jun 2.
Mechanochemical activation of coal is commonly employed in industry. However, even the simplest solid-phase reactions, such as neutralization of humic acids in brown coal, remain insufficiently studied. The hypothesis regarding the occurrence of mechanochemical neutralization under local hydrothermal conditions for humic acids in brown coal has been tested in this study. 3D modelling of the "block-interlayer" system (where coal particles are separated by air interlayers saturated with water vapor) was used. The 3D model showed that the permittivity is expected to rise from 14 to 16% as the moisture content in the system increases from 12 to 15%. The actual permittivities of coal with different moisture contents have been measured by dielectric spectroscopy. In the real system, the permittivity increases more than threefold as the moisture content rises from 12 to 15%. This increase is much greater than the calculated one, demonstrating that the phase containing unbound water appears in the system at a moisture content of ∼12-13% and may exert various effects on the solid-phase reaction. There is a correlation between the moisture content, permittivity, and predominant mechanisms of the reaction between the organic matter in brown coal and sodium percarbonate (a reagent simultaneously containing the alkaline and peroxidic components). The reactions between brown coal and alkaline reagents proceed under local hydrothermal conditions. Both the alkaline and peroxidic components of sodium percarbonate participate in the solid-phase reaction between brown coal and sodium percarbonate. The emergence of unbound water in coal significantly inhibits the oxidation reaction.
煤的机械化学活化在工业中普遍应用。然而，即使是最简单的固相反应，如褐煤中腐殖酸的中和反应，仍研究不足。本研究对褐煤中腐殖酸在局部水热条件下发生机械化学中和的假说进行了验证。采用了“块 - 夹层”系统的三维建模（其中煤颗粒被充满水蒸气的空气夹层隔开）。三维模型表明，随着系统中水分含量从12%增加到15%，介电常数预计将从14%升至16%。通过介电谱测量了不同水分含量煤的实际介电常数。在实际系统中，随着水分含量从12%升至15%，介电常数增加了三倍多。这种增加远大于计算值，表明在水分含量约为12 - 13%时系统中出现了含游离水的相，并且可能对固相反应产生各种影响。褐煤中有机质与过碳酸钠（一种同时含有碱性和过氧化物成分的试剂）之间的反应，其水分含量、介电常数和主要反应机制之间存在相关性。褐煤与碱性试剂之间的反应在局部水热条件下进行。过碳酸钠的碱性和过氧化物成分均参与褐煤与过碳酸钠之间的固相反应。煤中游离水的出现显著抑制了氧化反应。
