Fundamental Research Of Imidazolium-based And Phosphonium-based Ionic Liquids On Wetting Coal Seam

In the coal exploiting process, coal dust is a significant hidden danger and threatens human health. At present, coal seam water injection is a fundamental dust prevention measures. However, water is more polar which results that the directly wetting of coal seam by water is difficult, so that study of wetting agent or surfactant becomes hotspot. Room temperature ionic liquids(referred to as ionic liquids) are organic salts at or near room temperature which are entirely composed of the anions and cations, Based on the excellent solubility and designability of structure of ionic liquids(IL),we propose to use amphipathicity ILs to dissolve and wet coal structure, so that the effect of coal seam water injection can be improved fundamentally.In his paper, the wettability research objects were A liquor, 8 kinds of imidazolium-based ionic liquids which are [HOEtMIm][BF4]、[HOEtMIm][NTf2]、[AMIm][BF4] 、 [AMIm]Cl, [EMIm][BF4] 、 [EMIm][NTf2] 、 [PrMIm][BF4] 、[BMIm][BF4], and 2 kinds of phosphonium-based ionic liquids which are [P4,4,4,1][MeSO4] and [P4,4,4,2][DEP]. The wetting effect and evaporation resistance ability on different liquors to coal were tested in the experiments of contact angle and water retention. What’s more, the effect on ILs to active structure and minerals in the coal was analysized using the FTIR technology, which was the fundamental research of ILs to coal structural. This study will provide a new development platform for ionic liquids researching dust prevention and control as well as the structure in coal mine.Firstly, contact angles of A liquor and ILs to the surface of coal sample wa measured by contact angle instrument. Ths result proved that compared with distilled water, the contact angles of A liquor and ILs were all decrease, which states boths all have very good wetting effect, and the wettability of A solution is more clear. The contact angle of different ILs had large difference, that is, they have different wettability. Among of them, [HOEtMIm][NTf2] has the best effect, then [P4,4,4,1][MeSO4] and [P4,4,4,2][DEP] take the second place, and the worst wettability effect of all ILs is [HOEtMIm][BF4]. Comparing the contact angles of ILs containing the same cationic different anion and the same anion different cation, the author speculated cations wetting effect more apparent in ionic liquid.The moisture content gradient and equilibrium value of A liquor and ILs test coal were compared in the water retention experiment. The result proves that compared with distilled water, evaporation rate of A liquor and ILs test coal is slower, and their moisture can keep for a longer time, that is, the A liquor and ILs test coal samples show stronger resistance to evaporation capacity. The moisture content gradient and equilibrium value of different ILs are variant, and the water retention effect of [EMIm][BF4] is the best. Furthermore, the wettability and water retention capability of ILs have a certain connectivity, but the water retention effect of A liquor is not very apparent.FTIR experiment was operated to compare functional group change of ILs and water test coal. The results display that the main structure of coal is not transformed by Ils test coal, but the content of functional groups in coal is changed. Fatty hydrocarbon and aromatic hydrocarbon groups were all distinct weakened in the ILs test coal such as [PrMIm][BF4] 、 [BMIm][BF4] 、 [P4,4,4,2][DEP] 、 [AMIm]Cl 、[AMIm][BF4]、[HOEtMIm][NTf2]、[HOEtMIm][BF4]、[P4,4,4,1][MeSO4], at the same time, they were enhanced obviously in the[EMIm][BF4] and [EMIm][NTf2] test coal in which the oxygen class group was significantly receded. Comparing the spectrum peak intensity, the author presumes the ILs that can decrease fatty hydrocarbon and aromatic hydrocarbon groups usually has good wettability, and the effect of oxygen class groups to wettability may be related to the influence of the degree of weakening fatty hydrocarbon and aromatic hydrocarbon groups.