Molecular dynamics simulations and experimental study of the effects of an ionic surfactant on the wettability of low-rank coal

Hu, Jin; Zhang, Yansong; Dong, Hongtao; Zhang, Youning; Sun, Yingjun; Shi, Ji‐Quan; Li, Ruiting

doi:10.1016/j.fuel.2022.123951

Cited by 35 publications

(11 citation statements)

References 33 publications

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“…The increased hydrophilicity of the adsorbent surface caused by surfactants adsorption suggests that it occurs preferentially through the hydrocarbon tails with the polar heads of surfactants facing the aqueous phase. This agrees with the increase in wettability of carbonaceous materials promoted by the adsorption of surfactants highlighted by molecular dynamics studies (Liu et al 2020 ; Jin et al 2022 ).…”

Section: Resultssupporting

confidence: 88%

Hydrocarbons removal from synthetic bilge water by adsorption onto biochars of dead Posidonia oceanica

Cataldo

Muratore

Giannici

et al. 2022

Environ Sci Pollut Res

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Bilge waters are wastewaters produced on boats during navigation and usually contain hydrocarbons and oils. They cannot be directly released into the sea if not below a hydrocarbons concentration limit set by current legislation. Appropriate oil in water separator (OWS) systems can be installed on board boats to remove hydrocarbons from bilge water allowing their spillage into the sea. These systems may contain an adsorption step on a suitable adsorbent. Here, biochars produced from pyrolysis of dead Posidonia oceanica, pristine or chemically activated, have been tested as hydrocarbons adsorbents. Adsorption experiments with aqueous dispersions simulating bilge waters containing a marine gas oil (MGO) fuel for boats, a surfactant, and different NaCl concentrations were carrying out. The hydrocarbons concentrations before and after adsorption have been directly measured by using the reverse phase HPLC technique coupled with a fluorescence detector. These measurements are very fast and their reliability was verified by re-measuring the hydrocarbons concentrations of some samples with the GC–MS-MS technique, according to one of the traditional methods for hydrocarbons determination in emulsions. Different isotherm equations were used to fit the adsorption data. The biochars were characterized from the chemical-structural point of view by means of several instrumental techniques.

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Section: Resultssupporting

confidence: 88%

Hydrocarbons removal from synthetic bilge water by adsorption onto biochars of dead Posidonia oceanica

Cataldo

Muratore

Giannici

et al. 2022

Environ Sci Pollut Res

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“…To further explore the adsorption morphology distribution of AEO 9 on the anthracite surface, the relative concentration distribution of AEO 9 at the hydrophilic end and hydrophobic end was determined. Figure shows that AEO 9 is mainly distributed on the anthracite surface in the range of 20–40 Å, indicating that the surfactants form a dense network structure and are concentrated at the anthracite/H 2 O interface. , In combination with Figure , there is little difference between the peak positions of hydrophilic and hydrophobic sites of AEO 9 . The hydrophilic group peak appears at 33 Å and the hydrophobic peak appears at 31 Å.…”

Section: Resultsmentioning

confidence: 72%

“…Figure 10 shows that AEO 9 is mainly distributed on the anthracite surface in the range of 20−40 Å, indicating that the surfactants form a dense network structure and are concentrated at the anthracite/H 2 O interface. 35,36 In combination with Figure 10, there is little difference between the peak positions of hydrophilic and hydrophobic sites of AEO 9 . The hydrophilic group peak appears at 33 Å and the hydrophobic peak appears at 31 Å.…”

Section: Dynamic Simulation Analysis 341 Electrostatic Potential Anal...mentioning

confidence: 64%

Study of the Micromechanism of the Effect of Fatty Alcohol Poly(oxyethylene) Ether-9 on the Wettability of Jincheng Anthracite

et al. 2022

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The influence mechanism of the adsorption of fatty alcohol poly(oxyethylene) ether (AEO 9 ) on the wettability of anthracite coal was studied by means of experiments and simulations. First, the contact angle and surface tension were measured. When the AEO 9 concentration was 0.5 wt %, the contact angle and surface tension were the smallest, which were 10.28°and 25.39 mN m −1 , respectively. X-ray photoelectron spectroscopy (XPS) indicated that the content of C−O functional groups on the anthracite surface increased by 20.76% after adsorption of AEO 9 . The molecular orbital energy and electrostatic potential of AEO 9 and anthracite were calculated by density functional theory (DFT). There are two modes of electron transfer between the two orbitals: highest occupied molecular orbital (HOMO) transfer of AEO 9 to lowest unoccupied molecular orbital (LUMO) transfer of anthracite and HOMO transfer of anthracite to LUMO transfer of AEO 9 . The dynamics simulation results show that the addition of AEO 9 increases the migration rate of water molecules, promotes the movement of a large number of water molecules toward the surface of anthracite, and enhances the thickness of the water molecular layer on the surface of anthracite. The analysis of the relative concentration shows that AEO 9 is distributed at the anthracite/water interface. AEO 9 molecules are intertwined and connected by hydrophobic chains to form a network structure, which covers the anthracite surface horizontally, thus promoting the strength of the anthracite/water interaction.

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“…The optimal mole ratios of D–DDAB and MO–DDAB are both 9:1. When the dosage of DDAB continues to increase, the cumulative combustible recovery begins to decline, which may be due to the fact that DDAB solution is characterized by high viscosity, and when its concentration is too high, the dispersion of reagents will be weakened, thus reducing the adsorption effect of reagents on mineral surfaces and resulting in a poor flotation effect . When the amount of the mixed collector is more than 3000 g/t, the increase in cumulative combustible recovery is not obvious, but the cleaned coal ash increases slightly.…”

Section: Resultsmentioning

confidence: 99%

“…The substance composition and properties of coal molecules and collector solutions in this study can be distributed by whole atoms using this force field, which is consistent with what has been reported in other literature reports. 26 , 27 The shape optimization method was the Smart algorithm. After 5000 steps of iterative calculation, the geometrically optimized energy minimization model was obtained.…”

Section: Methodsmentioning

confidence: 99%

Enhanced Flotation Separation of Low-Rank Coal with a Mixed Collector: Experimental and Molecular Dynamics Simulation Study

Kang

Zhang

2022

ACS Omega

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The efficient flotation separation of low-rank coal is still a difficult problem. The development of a collector is the key to solve the problem. In this study, a kind of mixed collector scheme with a practical value is proposed. The effects of the single collector dodecane (D) and methyl oleate (MO) and mixed collector D–didodecyl dimethyl ammonium bromide (DDAB) and MO–DDAB on flotation separation of low-rank coal were investigated. The flotation test results show that when the molar ratios of the mixed collector D–DDAB and MO–DDAB are 9:1 and the flotation time is 4 min, the cumulative combustible recovery of low-rank coal flotation is 71.49 and 76.73%, respectively, and the cleaned coal ash is 15.26 and 13.03%, respectively. The mixed collector significantly improves the flotation effect of low-rank coal compared with the single collector. According to the analysis results of the contact angle, wetting heat, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy, the hydrophobicity of the low-rank coal surface is enhanced under the action of the mixed collector, and the adsorption between the mixed collector and coal surface is stronger. In addition, molecular dynamics (MD) simulation results show that compared with D or MO, DDAB tends to adsorb on the surface of low-rank coal, and the diffusion coefficients of water molecules on the surface of coal increase. The mixed collector first repels water molecules through its double hydrophobic carbon chain to weaken the binding of the coal surface to water molecules and then uses D or MO to further repel water molecules, thus effectively enhancing the surface hydrophobicity of low-rank coal.

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Molecular dynamics simulations and experimental study of the effects of an ionic surfactant on the wettability of low-rank coal

Cited by 35 publications

References 33 publications

Hydrocarbons removal from synthetic bilge water by adsorption onto biochars of dead Posidonia oceanica

Hydrocarbons removal from synthetic bilge water by adsorption onto biochars of dead Posidonia oceanica

Study of the Micromechanism of the Effect of Fatty Alcohol Poly(oxyethylene) Ether-9 on the Wettability of Jincheng Anthracite

Enhanced Flotation Separation of Low-Rank Coal with a Mixed Collector: Experimental and Molecular Dynamics Simulation Study

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