Molecular dynamics simulation of a lignite structure simplified model absorbing water

Chen, Zherui; Qiu, Hongxin; Hong, Zhixin; Wang, Guanghui

doi:10.1080/08927022.2019.1674851

Cited by 22 publications

(12 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After establishing the layered structure of different water molecules and the corresponding water molecular layers around the structure of coal molecules, the average interaction energies of water molecules could be obtained 11 , 36 from eq 2 . Note: E average —average interaction energies of water molecules; E —energies of coal–water molecules after steady state; E coal —energies of coal molecules; E n H 2 O —energies of water molecules; and n —number of water molecules.…”

Section: Resultsmentioning

confidence: 99%

“… 22 Until now, it has been widely used in the study of adsorption and interfacial properties. Chen et al 11 studied the formation mechanism of lignite hydration films by molecular dynamic simulation and determined that the H-bonds between the water and coal molecules are 1.8 Å on average. Kalinichev and Kirkpatrick 23 showed that the hydrophilicity of minerals strongly affects the formation of hydrated membranes through the hydration membrane model of different silicate minerals.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

View full text Add to dashboard Cite

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.

show abstract

Section: Resultsmentioning

confidence: 99%

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

View full text Add to dashboard Cite

show abstract

“…In this paper, we adopted the COMPASS force field, which can accurately and rapidly predict the structural and thermophysical properties of organic matter and is widely used in the simulation of coal-related products and their adsorption [16,27,29,53,54]. The composition of the molecular potential energy is as follows.…”

Section: The Details Of Simulation and Calculationmentioning

confidence: 99%

O2 Physisorption in Coal Pore: Effects of Pore Size, Pressure, Temperature and Function Group

Cheng

Tan

et al. 2022

Preprint

View full text Add to dashboard Cite

In this paper, the physical adsorption characteristics of oxygen in coal pores were systematically investigated by the Grand Canonical Monte Carlo and the COMPASS force field. Firstly, coal pore structures of different sizes were constructed by graphite slit models and different groups. Secondly, the physisorption behavior of oxygen in graphite slit models of different sizes was simulated. Finally, the physisorption behavior of oxygen in graphite slit models at different pressures and temperatures was analyzed. The results showed that the physisorption density and excess physical adsorption of oxygen were divided into the rapidly decreasing stage (0.4-0.7 nm), the slowly decreasing stage (0.7-1.4 nm), and the stable stage (1.4 nm-5 nm) with the increase of coal pores, and the excess oxygen physisorption amount was more sensitive to the change of pressure. The O2 isosteric heat of physisorption decreased with increasing pore size of coal. Oxygen is more strongly adsorbed by hydroxyl and ether bonds than by methyl, carboxyl and carbonyl groups. Through this study, the mechanism of oxygen physical adsorption in coal pores and the characteristics influenced by temperature and pressure can be better understood.

show abstract

“… 14 − 17 This is because the oxygen-containing functional groups are polar and can efficiently adsorb polar molecules such as water to form a tight hydration film on the surface of lignite. 18 Similarly, the absorption of water on the pores of the lignite surface increases the degree of hydration on the lignite surface, resulting in poor lignite flotability. Research on flotation agents to improve the floatability of lignite has been conducted.…”

Section: Introductionmentioning

confidence: 99%

“…The abundant oxygen-containing functional groups and complex pore distribution on the surface of lignite also have an important influence on lignite flotation. − This is because the oxygen-containing functional groups are polar and can efficiently adsorb polar molecules such as water to form a tight hydration film on the surface of lignite . Similarly, the absorption of water on the pores of the lignite surface increases the degree of hydration on the lignite surface, resulting in poor lignite flotability.…”

Section: Introductionmentioning

confidence: 99%

Effect of Dodecyl Trimethyl Ammonium Bromide on the Migration of Water Molecules in the Pores of Lignite: An Experimental and Molecular Simulation Study

2020

Self Cite

View full text Add to dashboard Cite

Molecular dynamics simulations and experiments were used to study the influence of dodecyl trimethyl ammonium bromide (DTAB) on the migration of water molecules in the pores of lignite. To simulate the accuracy, 13 C NMR was used to confirm the structure of Shengli lignite. It was found through adsorption experiments that DTAB reduces the specific surface area and pore volume of lignite. Molecular simulations indicate that the lignite and water molecules are primarily connected by hydrogen bonding. DTAB impedes the movement of water molecules in the pores of lignite and the storage space of compressed water molecules. Water molecules are mainly present in the pores of lignite in a posture parallel to the XOY plane, which facilitates the formation of hydrogen-bonding networks. However, this also leads to a decrease in the mobility of water molecules. Experimental and simulation results show that DTAB can enter lignite pores, reducing the water absorption in lignite. This is highly significant for the processing and utilization of lignite.

show abstract

Molecular dynamics simulation of a lignite structure simplified model absorbing water

Cited by 22 publications

References 21 publications

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

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

O2 Physisorption in Coal Pore: Effects of Pore Size, Pressure, Temperature and Function Group

Effect of Dodecyl Trimethyl Ammonium Bromide on the Migration of Water Molecules in the Pores of Lignite: An Experimental and Molecular Simulation Study

Contact Info

Product

Resources

About