Spreading behavior of dodecane-oleic acid collector mixture in low-rank coal flotation

Liao, Yinfei; Yang, Zhe; An, Maoyan; Cao, Yijun; Hao, Xiaodong; Song, Xingwei; Ren, Hourui; Yang, Aosheng; Chen, Luojian

doi:10.1016/j.fuel.2021.122071

Cited by 26 publications

(8 citation statements)

References 36 publications

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“…The density field distribution of oil drops was consistent with the results of equilibrium contact angle analysis. Liao et al experimentally measured the contact angle between LOC and dodecane oil drops in an aqueous environment to be 115.3°, whereas the equilibrium contact angle simulated in this paper is relatively small, which is likely to be related to the selection of coal samples [18]. Both experimental and simulation results showed that the oil drops were in large oil clusters on the LOC surface with poor dispersion, adsorption and spreading efficiency.…”

Section: Resultsmentioning

confidence: 73%

“…The results showed that the contact angle of dodecane on the coal surface was the largest and the contact angle of the dodecane-oleic acid mixture was the smallest. The addition of oleic acid enhanced the adsorption of its mixture to the coal surface, but slowed down the diffusion rate, which improved the flotation efficiency [18]. However, all of the above are studied experimentally, and in recent years, with the gradual rise of molecular simulation, it has been widely used in chemistry, physics, materials, and biology [19][20][21][22].…”

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confidence: 99%

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Study on the microscopic mechanism of adsorption and diffusion of hydrocarbon oil drops on coal surface using molecular dynamics simulations

Zhao,

Liu

2023

Int J of Quantum Chemistry

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Flotation of fine coal particles usually uses oil collectors, but the micromechanisms need to be more refined due to the complex structure and abundant functional groups on the surface of coal bodies. The adsorption spreading behavior and interfacial properties of nonpolar oil drops on flat low‐order coal (LOC) and high‐order coal (HOC) surfaces were investigated in depth using molecular dynamics (MD) simulations, while the effects of different functional groups on LOC surfaces were also considered. The results showed that the contact angle, contact area and interaction energy of oil drops adsorbed on the LOC and HOC surfaces at simulated equilibrium in aqueous environment were 77.68°, 621.49 Å2, −140.94 kcal/mol; 53.98°, 962.14 Å2, and −195.13 kcal/mol, respectively. The smaller the equilibrium contact angle between the oil drops and the surface, the larger the contact area and the larger the absolute value of the interaction energy, the better the spreading effect of the oil drops and the easier the surface is to flotation. Compared with the HOC surface, the oil drops could not displace the water molecules on the LOC surface better and spread poorly on its surface, and the migration rate was higher. This was caused by the abundant functional groups on the surface of LOC. The type of functional group significantly affects the interaction of nonpolar oil drops with hydrophilic surfaces, with the order of adsorption strength being CH3 > COCH3 > OH > COOH. The formation of a dense hydrated film of oil drops on the COOH surface was an important reason for the difficulty of flotation on the LOC surface. MD elucidated the mechanism of action of nonpolar oil collectors on LOC and HOC surfaces, which is a guide for efficient flotation on LOC surfaces.

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Section: Resultsmentioning

confidence: 73%

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confidence: 99%

Study on the microscopic mechanism of adsorption and diffusion of hydrocarbon oil drops on coal surface using molecular dynamics simulations

Zhao,

Liu

2023

Int J of Quantum Chemistry

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“…Our team has been committed to the study on the mechanism of mixed collectors to strengthen the LRC flotation. ,− In our previous work, the detachment force of air bubbles detached from the LRC surface after collector treatment was studied, In this paper, the energy feature of bubble detachment from the LRC surface in the presence of D, OA, and their mixture (OA–D) was investigated. The property of the coal samples was analyzed using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), contact angle measurement, and wetting heat measurement.…”

Section: Introductionmentioning

confidence: 99%

Energy Feature of Air Bubble Detachment from a Low-Rank Coal Surface in the Presence of a Dodecane–Oleic Acid Collector Mixture

Liao

Yang

et al. 2022

ACS Omega

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It has been generally proved that mixed collectors can enhance the flotation of low-rank coal (LRC). However, the inhibition effect of mixed collectors on the detachment between particles and bubbles is still unclear. In this paper, the energy feature of air bubble detachment from the LRC surface in the presence of dodecane (D), oleic acid (OA), and the mixture of dodecane and oleic acid (OA–D) was studied. The effect of collectors on the LRC surface property was analyzed using contact angle measurement, X-ray photoelectron spectroscopy, and wetting heat measurement. The force and displacement during the detachment process were measured synchronously using microforce balance. The results showed that the collector treatment increased the C–C/C–H content and decreased the content of oxygen-containing groups on the LRC surface. The synergistic effect between OA and D enabled the mixed collector to exhibit higher contact angle and wetting heat. Bubble detachment from the LRC surface can be divided into two stages: bubble stretching and bubble sliding, which corresponded to activation energy and detachment work, respectively. The activation energy and detachment work decreased in the same order of OA–D > OA > D, indicating that the mixed collector OA–D increased the energy of bubble detachment from the LRC surface and enhanced the adhesion strength. The theoretical detachment work was calculated, and the calculated results were in agreement with the measured results. This research provides a new perspective on the mechanism of LRC flotation being improved by mixed collectors.

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“…Xia et al revealed the synergistic adsorption structures of dodecane and dodecanoic acid on oxygen-containing graphite surfaces using molecular dynamics (MD) simulations. Liao et al investigated the spreading behaviors of dodecane, oleic acid, and a dodecane–oleic acid mixture on low-rank coal surfaces, through contact angle relaxation tests and molecular kinetic (MK) model fitting. Yang et al implemented mineral surface analysis and molecular dynamics, establishing a model to separate hornblende from siderite with decaethoxylated stearylamine as the collector.…”

Section: Introductionmentioning

confidence: 99%

Molecular Resolution Imaging of Adsorption of Dodecane on a Lignite Surface by Frequency Modulation AFM

Wang

2022

Energy Fuels

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The consumption of dodecane, a critical flotation collector, in the flotation of low-rank coal is particularly high; however, the adsorption mechanism of dodecane on coal still remains unclear. To shed light on this issue, the molecular-scale adsorption structure of dodecane on a lignite surface was investigated in situ by frequency modulation atomic force microscopy (FM-AFM) for the first time. The adsorption structure of dodecane on highly oriented pyrolytic graphite (HOPG) and mica has been detected in advance. Meanwhile, molecular dynamics (MD) simulations are utilized to elucidate and illustrate the adsorption structure on HOPG, mica, and lignite. Experimental results from FM-AFM show that a layered structure of dodecane molecules is formed on HOPG, while there is no stable adsorption structure on mica. Meanwhile, a few local monolayer structures of dodecane molecules are observed on the surface of lignite, and their thickness is approximately 1 nm, which is less than the molecular chain length of dodecane. It is speculated that the dodecane molecules are adsorbed on lignite selectively, with the capacity to form a stable adsorption structure. As indicated by MD simulations, the interaction energy between dodecane and the mentioned surfaces is in the order HOPG > lignite > mica. And the MD simulation results show a desirable match with direct observation by FM-AFM. In accordance with the characterization of the lignite sample surface, large amounts of polar oxygen-containing functional groups may hinder dodecane adsorption behavior. Through in situ molecular resolution imaging of the interface structure between dodecane and a raw lignite surface, we provide a new perspective for exploring the interaction mechanism between nonpolar collectors and a lignite surface.

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Spreading behavior of dodecane-oleic acid collector mixture in low-rank coal flotation

Cited by 26 publications

References 36 publications

Study on the microscopic mechanism of adsorption and diffusion of hydrocarbon oil drops on coal surface using molecular dynamics simulations

Study on the microscopic mechanism of adsorption and diffusion of hydrocarbon oil drops on coal surface using molecular dynamics simulations

Energy Feature of Air Bubble Detachment from a Low-Rank Coal Surface in the Presence of a Dodecane–Oleic Acid Collector Mixture

Molecular Resolution Imaging of Adsorption of Dodecane on a Lignite Surface by Frequency Modulation AFM

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