A comparison of desorption process of Chinese and Australian lignites by dynamic vapour sorption

He, Qiang; Huang, Shaomeng; Wan, Keji; Xu, Huaizhe; Miao, Zhenyong

doi:10.1080/01496395.2016.1158192

Cited by 8 publications

(17 citation statements)

References 53 publications

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“…Unexpectedly, when six water molecules were adsorbed, the size of the water cluster was larger, and it interacted with another OFG close to it. Therefore, the size and configuration of the water clusters were related to the local density of sites and their relative location, and not the overall site density …”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the size and configuration of the water clusters were related to the local density of sites and their relative location, and not the overall site density. 22…”

Section: Resultsmentioning

confidence: 99%

“…Water molecules were added one by one near O–H to optimize the structure. The size of the water cluster was six to seven water molecules, as obtained by fitting the experimentally obtained lignite moisture desorption isotherm . The optimized structure of n H 2 O@O–H ( n = 1–7) is shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…An ab initio investigation of water cluster suggested that the smaller clusters with n = 4, 5, or 8 could be used as the basic building blocks for generating larger clusters . In our previous dynamic vapor sorption experiment of lignites, we fitted our adsorption/desorption isotherms with the D.D model , and found that the critical size of water clusters penetrating and residing in the lignite micropores was six to seven water molecules.…”

Section: Introductionmentioning

confidence: 94%

“…The water cluster size is dependent on the physicochemical structure of the materials. − Do et al , suggested that water molecules are adsorbed around the OFGs in the form of clusters, and water is adsorbed into the micropores when the concentration of this water cluster is high enough. An ab initio investigation of water cluster suggested that the smaller clusters with n = 4, 5, or 8 could be used as the basic building blocks for generating larger clusters .…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Water Clusters in Lignite and Desorption Energy Calculation by Density Functional Theory

He¹,

Xiao²,

Miao³

et al. 2019

ACS Omega

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The interaction of water and hydrophilic sites with hydroxyl, carboxyl, and multiple oxygen-containing functional groups (OFGs) in lignite molecules was studied by density functional theory. The adsorption of water molecules on the lignite surface initially resulted in the formation of hydrogen bond-driven stable rings by three to four water molecules, followed by the formation of three-dimensional water clusters like a ″patchwork″. Aqueous layer thickness obtained from the water cluster size was 0.4–0.6 nm, which was consistent with the experimental data. Thus, pore-filling water beyond this range was less affected by the OFGs on the surface. Calculation of the adsorption energy predicts that the water clusters were primarily formed in the hydrophilic sites with three OFGs (site 1, including a carbonyl group, an alcoholic hydroxyl group and an etheroxy group in tetrahydropyran), then in COOH, and in O–H. For isolated hydroxyl groups, the interaction between the hydroxyl group and water molecules was weaker than that between the water molecules. When the water cluster was located at the hydrophilic sites with two or more OFGs, the adsorption energy of lignite–water interaction was higher than that of water–water interaction. Investigating the thermodynamics of the adsorption process at a molecular scale will help in understanding both drying and resorption process of dried lignite during industrial production.

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Section: Resultsmentioning

confidence: 99%

“…Therefore, the size and configuration of the water clusters were related to the local density of sites and their relative location, and not the overall site density. 22…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%