Analysis of coal wettability by inverse gas chromatography and its guidance for coal flotation

Niu, Chenkai; Xia, Wencheng; Peng, Yaoli

doi:10.1016/j.fuel.2018.04.146

Cited by 52 publications

(19 citation statements)

References 30 publications

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“…However, these methods are often time-consuming and laborious. Thus, inverse gas chromatography (IGC) has been applied to the study of the thermodynamic properties of polymers, carbon blacks, ILs, and other materials [16,17]. In addition, Dr. Charles M. Hansen has proposed the Hansen solubility parameter (HSP) theory, which splits the Hildebrand solubility parameter into three parts: the dispersive interactions, δD, the polar interactions, δP, and the hydrogen bonding interactions, δH.…”

Section: Introductionmentioning

confidence: 99%

Practical Determination of the Solubility Parameters of 1-Alkyl-3-methylimidazolium Bromide ([CnC1im]Br, n = 5, 6, 7, 8) Ionic Liquids by Inverse Gas Chromatography and the Hansen Solubility Parameter

Zhu

Wang

et al. 2019

Molecules

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The physicochemical properties of four 1-alkyl-3-methylimidazolium bromide ([CnC1im]Br, n = 5, 6, 7, 8) ionic liquids (ILs) were investigated in this work by using inverse gas chromatography (IGC) from 303.15 K to 343.15 K. Twenty-eight organic solvents were used to obtain the physicochemical properties between each IL and solvent via the IGC method, including the specific retention volume and the Flory–Huggins interaction parameter. The Hildebrand solubility parameters of the four [CnC1im]Br ILs were determined by linear extrapolation to be δ 2 ( [ C 5 C 1 im ] Br ) = 25.78 (J·cm−3)0.5, δ 2 ( [ C 6 C 1 im ] Br ) = 25.38 (J·cm−3)0.5, δ 2 ( [ C 7 C 1 im ] Br ) =24.78 (J·cm−3)0.5 and δ 2 ( [ C 8 C 1 im ] Br ) = 24.23 (J·cm−3)0.5 at room temperature (298.15 K). At the same time, the Hansen solubility parameters of the four [CnC1im]Br ILs were simulated by using the Hansen Solubility Parameter in Practice (HSPiP) at room temperature (298.15 K). The results were as follows: δ t ( [ C 5 C 1 im ] Br ) = 25.86 (J·cm−3)0.5, δ t ( [ C 6 C 1 im ] Br ) = 25.39 (J·cm−3)0.5, δ t ( [ C 7 C 1 im ] Br ) = 24.81 (J·cm−3)0.5 and δ t ( [ C 8 C 1 im ] Br ) = 24.33 (J·cm−3)0.5. These values were slightly higher than those obtained by the IGC method, but they only exhibited small errors, covering a range of 0.01 to 0.1 (J·cm−3)0.5. In addition, the miscibility between the IL and the probe was evaluated by IGC, and it exhibited a basic agreement with the HSPiP. This study confirms that the combination of the two methods can accurately calculate solubility parameters and select solvents.

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Section: Introductionmentioning

confidence: 99%

Practical Determination of the Solubility Parameters of 1-Alkyl-3-methylimidazolium Bromide ([CnC1im]Br, n = 5, 6, 7, 8) Ionic Liquids by Inverse Gas Chromatography and the Hansen Solubility Parameter

Zhu

Wang

et al. 2019

Molecules

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“…The difference between absolute adsorption capacity and saturated adsorption capacity is that adsorption equilibrium of the absolute adsorption capacity is a process that reflects whether the adsorption process reaches equilibrium, while the adsorption saturation of saturated adsorption capacity is a state reflecting whether the adsorbent reaches the saturation state. 57 In this paper, the saturated adsorption capacity A directly reflects the limit adsorption capacity of coal molecules. When the adsorption capacity reaches saturation, the surfaces of coal molecules are occupied by methane molecules, and methane molecules are no longer adsorbed.…”

Section: Construction and Simulation Of Thementioning

confidence: 99%

“…With the increase of water content, its gas adsorption capacity on coal molecules is relatively weakened. According to the relevant literature, − the moisture content was the primary factor affecting the adsorption capacity from low-rank coal to flue gas; the influence of water content on high-rank coal is relatively low, accounting for less than 5%, followed by medium-rank coal (4–20%), while low-rank coal was affected by water content more (up to nearly 40%). The main reason is that there are polar oxygen functional groups on the surface of low-rank coal, such as hydroxyl group, carboxyl group, and carbonyl group.…”

Section: Construction and Simulation Of The Molecular Modelmentioning

confidence: 99%

Methane Adsorption Influence and Diffusion Behavior of Coking Coal Macromolecules under Different Moisture Contents

et al. 2020

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To study the adsorption and diffusion behavior of methane on coal macromolecules under different moisture contents, the macromolecular model of coking coal was established through elemental analysis and 13 C NMR and X-ray photoelectron spectrum (XPS) experiments. Using this molecular model, the variation of methane adsorption capacity under five different moisture contents (0, 1.4, 2.3, 3.2, and 4.4%) was investigated. The effect of methane adsorption was explained from energy distribution and the radial distribution function (RDF). Finally, the diffusion behavior of methane on adsorption capacity was studied according to the diffusion coefficient. Simulation results indicate that absolute adsorption capacity and saturated adsorption capacity of methane decrease with the increase of moisture content. Compared with experimental results, the relative adsorption error of the saturated adsorption A is 7.49%; the curve trend of the simulation results is basically consistent with the experimental results, which conforms to the law of the Langmuir adsorption curve (type I). From the energy point of view, the methane molecular priority at the adsorption site is between −22 and −20 kJ/mol and the peak value is about −19.4 kJ/mol, which is not better than the adsorption position. Based on the heteroatoms in the model, the influence of the oxygen atom and the sulfur atom on methane adsorption is stronger than that of the nitrogen atom. Through the calculation of the diffusion coefficient, the diffusion coefficient decreases with the increase of the moisture content, which leads to the decrease of the absolute and saturated adsorption capacities. On the basis of this fact, the diffusion coefficient is found to directly affect the adsorption capacity and adsorption characteristics. This conclusion provides a valuable reference and a new way to study similar coal molecules.

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“…Their chemical activity is relatively high, with hydroxyl groups being the most pronounced. 4 , 5 Compared to lignite, this coal species is not more hydrophilic than lignite and does not easily cause the aqueous system’s hydration. 6 − 8 Because lignite has large moisture (15–60%) and is mainly used for power generation, while 1/3 of coking coal is mainly used for coking and tailings treatment and has a high degree of development and metamorphism, with hydrophilicity of 4–20%, exhibiting less porosity and closing some pores, its hydrophilic capacity is relatively weaker than that of lignite.…”

Section: Introductionmentioning

confidence: 99%

Dynamic Simulation Based on a Simplified Model of 1/3 Coking Coal Molecule and Its Formation Characteristics of Hydration Films

Zhu

Zhang

et al. 2021

ACS Omega

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To comprehensively elaborate the formation characteristics of hydration films on 1/3 coking coal molecule, this paper reports the construction of a realistic simplified model for calculations of electrostatic potentials on the coal molecular surface to foresee the major immersion locations. On this basis, interactions at the interface of coal molecules with different numbers of water molecules and their effects on each functional group of coal molecules were investigated. Using the scanning electron microscopy experiment, changes in the coal matrix before and after water leaching were compared and analyzed by fractal dimension calculations. Hydration characteristics of coal were described from a combined macroscopic and microscopic perspective. The results showed that both positive and negative electrostatic potential of coal molecules occurred near the O-containing functional groups. The hydroxyl group’s electrostatic potential (−OH) rose, resulting in higher electrostatic potential in coal–water molecules and providing many immersion sites. Deficiency in water molecules led to the complete immersion of water molecules. The interface of coal molecules could not be covered entirely, which led to the low number of active sites and Z values. The interface of coal–water molecules did not affect the average bond lengths of water molecules but decreased the bond angle by 3–4°. The influence ofwater molecules on the −OH groups of coal molecules was the most prominent when water molecules were incorporated into the coal molecules. Water damage for the coal matrix is more pronounced than in the raw coal itself. In view of above research, the formation characteristics of the hydration film from a microscopic point of view explained that the initial hydration of coal molecules was owing to H-bonds. From a macroscopic perspective, it was mainly due to structure changes for the coal matrix. This provides valuable references for field experiments in hydraulic fracturing and perforation.

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Analysis of coal wettability by inverse gas chromatography and its guidance for coal flotation

Cited by 52 publications

References 30 publications

Practical Determination of the Solubility Parameters of 1-Alkyl-3-methylimidazolium Bromide ([CnC1im]Br, n = 5, 6, 7, 8) Ionic Liquids by Inverse Gas Chromatography and the Hansen Solubility Parameter

Practical Determination of the Solubility Parameters of 1-Alkyl-3-methylimidazolium Bromide ([CnC1im]Br, n = 5, 6, 7, 8) Ionic Liquids by Inverse Gas Chromatography and the Hansen Solubility Parameter

Methane Adsorption Influence and Diffusion Behavior of Coking Coal Macromolecules under Different Moisture Contents

Dynamic Simulation Based on a Simplified Model of 1/3 Coking Coal Molecule and Its Formation Characteristics of Hydration Films

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