Experimental and molecular dynamics simulation study of the effect of different surfactants on the wettability of low-rank coal

Yuan, Mengwei; Nie, Wen; Yu, Hai; Yan, Jerry; Qiu, Bao; Zhou, Weiwei; Hua, Yun; Guo, Lidian; Niu, Wenjin

doi:10.1016/j.jece.2021.105986

Cited by 60 publications

(19 citation statements)

References 31 publications

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“…The coal dust aggregation is caused by the physical accumulation under the action of gravity. 53 Moreover, the coal dust treated with deionized water and WBF solution is smoother and the particle gap expands relative to APSF. The surface morphology of coal dust treated with APSF becomes coarser, as illustrated in Figure 8h,i.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The coal dust treated with deionized water and WBF solution presents a dispersed state and just has a small amount of aggregation, while the coal dust treated with APSF solution takes on more congregate distribution. The coal dust aggregation is caused by the physical accumulation under the action of gravity . Moreover, the coal dust treated with deionized water and WBF solution is smoother and the particle gap expands relative to APSF.…”

Section: Resultsmentioning

confidence: 99%

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High-Efficient Dust Trapping Performance of AES/Polyacrylamide Strengthen Foam Based on the Structure Stability and Dust Wettability

Xing

et al. 2022

Langmuir

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The atmospheric dust has a great negative impact on the societal harmonious development that starves for an efficient dust suppressant. This paper proposes a novel AES/polyacrylamide strengthen foam (APSF) to improve the dust trapping effectiveness. The APSF structure property and dust suppression capacity are studied and evaluated through the molecular dynamics simulation and experimental tests. The results express that APSF exhibits the stronger structure stability, superior water retention, and slower drainage performance than the traditional water-based foam (WBF). APSF dynamic simulation is studied by the relative concentration, radial distribution function, head group orientation, and mean square displacement. Research shows that APSF introduces water to thicken the hydration layer. The interaction strength between water and surfactant head groups is enhanced by 22.62 and 31.37% in the first and second hydrated water shells. APSF improves the sodium fatty alcohol ether sulfate (AES) orientation and weakens the diffusion of water molecules, which favors the foam stability. APSF exerts a better wettability on the coal dust through the wet settlement and contact angle tests. The APSF liquid film thickness reduces to 58.05 from 64.80 μm that is 3.14 times of WBF according to the foam liquid film decay experiment. Fourier transform infrared (FTIR) spectroscopy analysis indicates that there is an evident reinforcement on the coal surface absorption peak intensity of hydroxyl-and oxygen-containing functional groups treated by APSF. FTIR results are further determined by energy-dispersion spectrum analysis.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

High-Efficient Dust Trapping Performance of AES/Polyacrylamide Strengthen Foam Based on the Structure Stability and Dust Wettability

Xing

et al. 2022

Langmuir

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“…The MSD and diffusion coefficient D can characterize the speed of molecular movement to some extent. , The equation of motion is as follows MSD = 1 N ∑ i = 1 N false[ r i ( t ) − r i ( 0 ) false] 2 D = 1 6 N lim t → ∞ nobreak0em.25em⁡ normald normald t ∑ i = 1 N false[ r i ( t ) − r i ( 0 ) false] 2 D = lim t → ∞ ( M S D 6 t ) = 1 6 K normalM normalS normalD where MSD represents the mean square displacement; N represents the total number of diffusion molecules; r ( t ) and r (0) are the position vectors of i molecule at time t and t = 0, respectively; and K MSD represents the slope of the MSD curve, that is, the diffusion coefficient is 1/6 of the slope of the MSD curve.…”

Section: Resultsmentioning

confidence: 99%

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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“…However, the effects of amphoteric surfactants on the coal structures and CH 4 adsorption characteristics are not well known. Therefore, it is necessary to carry out experiments to investigate the effects of amphoteric surfactants on coal, so we selected cocamidopropyl betaine (CAB) to study because of its cheap, safe, and nonpolluting advantages. , …”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Coal Structure Variation and CH₄ Adsorption Properties under the Effect of Cocamidopropyl Betaine

et al. 2022

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Surfactants can be used to improve the coal surface wettability and reduce the CH 4 adsorption capacity of coals, so they are usually added to fracturing fluids to promote coalbed methane (CBM) production. In this work, the impacts of a surfactant cocamidopropyl betaine (CAB) on coal structures and CH 4 adsorption characteristics were investigated. The CAB solutions with five CAB concentrations (0, 0.002, 0.006, 0.008, and 0.01 mol/L) were prepared and used to treat coal samples. The treated coal samples were dried and tested for infrared spectroscopy experiments, liquid nitrogen adsorption experiments, and CH 4 adsorption experiments. The results indicate that the hydrophilicity of the coal samples was enhanced after being treated with CAB solutions; the number of hydroxyl functional groups increased; and some aliphatic, aromatic, and oxygen-containing structures disappeared, which promoted the replacement of CH 4 by H 2 O and reduced the amount of adsorbed CH 4 . Meanwhile, the pore volume of the coal samples increased and the CBM migration rate was improved. Among the five CAB concentrations, 0.008 mol/L CAB was determined to be an optimal concentration to increase the CBM extraction efficiency. Compared to the untreated coal, the amount of adsorbed CH 4 decreased by 13.18% and the CBM migration channel volume increased by 16.74% at 0.008 mol/L CAB. The results reported in this work will offer new insights into the improvement of CBM extraction efficiency using CAB.

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Experimental and molecular dynamics simulation study of the effect of different surfactants on the wettability of low-rank coal

Cited by 60 publications

References 31 publications

High-Efficient Dust Trapping Performance of AES/Polyacrylamide Strengthen Foam Based on the Structure Stability and Dust Wettability

High-Efficient Dust Trapping Performance of AES/Polyacrylamide Strengthen Foam Based on the Structure Stability and Dust Wettability

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

Experimental Study on Coal Structure Variation and CH₄ Adsorption Properties under the Effect of Cocamidopropyl Betaine

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Experimental and molecular dynamics simulation study of the effect of different surfactants on the wettability of low-rank coal

Cited by 60 publications

References 31 publications

High-Efficient Dust Trapping Performance of AES/Polyacrylamide Strengthen Foam Based on the Structure Stability and Dust Wettability

High-Efficient Dust Trapping Performance of AES/Polyacrylamide Strengthen Foam Based on the Structure Stability and Dust Wettability

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

Experimental Study on Coal Structure Variation and CH4 Adsorption Properties under the Effect of Cocamidopropyl Betaine

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Experimental Study on Coal Structure Variation and CH₄ Adsorption Properties under the Effect of Cocamidopropyl Betaine