Effect of -O- on Water Molecule Adsorption and Adsorption Mechanism of Lignite and Coke

Bai, Xue; Song, Yue Yin; Teng, Ying Yue; Zhang, Wen Lu; Song, Yinmin; Wang, Yun Fei

doi:10.1155/2021/5573498

Cited by 3 publications

(3 citation statements)

References 20 publications

(26 reference statements)

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“…Such coal samples were referred to as adsorbed water samples. The interaction strength between lignite and water molecules is expressed as the transverse relaxation time T 2 (ms) as follows: M x y = M 0 × exp ( − t T 2 ) where M xy is the component of the macroscopic magnetization vector on the x – y axis, M 0 is the initial magnetization vector, and T 2 is the transverse relaxation time. The interaction intensity M xy is proportional to the relaxation time t , according to eq .…”

Section: Methodsmentioning

confidence: 99%

“…The hydrophilicity sequence of these functional groups is as follows: carboxyl group > phenolic hydroxyl group > carbonyl group > methoxy group. The dehydration energy of samples with more carboxyl groups is lower than that of samples with more phenolic hydroxyl groups. − It has been verified that increasing the ether bond content in lignite leads to a significant enhancement in the water adsorption capacity, and the ether bonding can cause water molecules to form a stable adsorption monolayer of water . Moisture resorption is also influenced by the pore structure of lignite.…”

Section: Introductionmentioning

confidence: 99%

“…11−15 It has been verified that increasing the ether bond content in lignite leads to a significant enhancement in the water adsorption capacity, and the ether bonding can cause water molecules to form a stable adsorption monolayer of water. 16 Moisture resorption is also influenced by the pore structure of lignite. During the drying and upgrading of lignite, the specific surface area and total volume of lignite increase; however, the gelatinous structure shrinks and collapses significantly, reducing the hydrophilicity of dehydrated lignite, therefore, restricting water reabsorption.…”

Section: Introductionmentioning

confidence: 99%

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Enhancement Mechanism of Minerals on Lignite–Water Molecule Interactions

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Five coal samples were prepared by deashing Shengli lignite in distinct phases, which consisted of residual ash from spontaneous combustion. The effects of removal and introduction of inherent minerals on the water reabsorption performance of coal samples were systematically investigated in three aspects: pore structure, oxygen-containing functional groups, and lignite materials. Low-field nuclear magnetic resonance spectroscopy was employed to investigate the changes in the water molecular adsorption tendency of coal samples with the variation in the mineral content. The study elucidates that the hygroscopic performance of the coal samples is significantly reduced due to the massive removal of inherent minerals. However, the pore structure of the coal samples after HCl/HF washing becomes more developed, and the oxygen-containing functional groups on the surface are more exposed, leading to an increase in the equilibrium adsorbed moisture content (EMC) of the coal samples. The binding force between coal samples and water molecules is reduced by the removal of the inherent minerals, which weakens the interaction forces between lignite and water molecules. The oxygen-containing functional groups on the surface of lignite interact with the residual ash from spontaneous combustion to enhance the binding force between lignite and surface water molecules, thus leading to the improved tendency of lignite to adsorb water molecules. The formation of intermediate complexes between minerals and oxygen-containing functional groups, in particular, carboxyl functional groups, on the surface of lignite enhances the acting force of polar sites, which improves the interaction of lignite–water molecules.

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