APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Xiangming Hu,Jingran Mao,Qian Zhang,Xuechao Dong,Haigang Du,Mingyue Wu,Weimin Cheng,Zhenyu Yang
Understanding the adhesion mechanism between polydopamine (PDA) and coal surface is crucial for implementing the mussel strategy in self-adhesive gel for fire suppression. In this study, a combination of experiments and molecular simulations was utilized to explore the interfacial adhesion mechanism between PDA and coal. Initially, the adhesion potential of varying concentrations of PDA solutions was evaluated using a UV–Vis spectrophotometer, and in conjunction with contact angle/surface tension measurements, it was observed that adhesion strength did not show a direct correlation with PDA concentration. Subsequently, the adhesion sites of PDA on the coal surface were identified through spectroscopic analysis and confirmed using Dmol3 simulations. The study revealed that the amino and phenolic hydroxyl groups in the PDA structure could establish hydrogen bonds with oxygen-containing functional groups on the coal surface (e.g., COOH, OH, R-O-R'), while the aromatic rings in the molecules engaged in π-π stacking interactions. These non-covalent forces collectively facilitated the adhesion process. Molecular dynamics (MD) simulations were then employed to validate the relationship between PDA solution concentration and adhesion strength, which aligned with the experimental findings. Furthermore, the MD simulations elucidated how the concentration of PDA solution influenced its interfacial adhesion strength with coal by considering water molecule diffusion. Overall, this research offers a theoretical foundation for designing self-adhesive gel for fire suppression.
研究领域:
材料科学
·
化学工程
·
分子生物学
✓ 已验证
产品关联
DOI
高影响因子
MINERALS ENGINEERING
·
2019
·
IF 3.315
Wenjie Zou,Lu Gong,Jun Huang,Mingfei Pan,Zhenzhen Lu,Chunbao Sun,Hongbo Zeng
Selective flocculation is an efficient separation method for processing fine coal. In this work, one type of hydrophobically modified polyacrylamide, poly(AM-NaAA-C 16 DMAAC) (HMPAM), was synthesized and used as flocculants of coal. The adsorption and interaction of HMPAM on model coal surface under the influence of KCl concentration were compared with a commercial polyacrylamide (PAM) using quartz crystal microbalance with dissipation monitoring (QCM-D), multi-angle laser light scattering (MALLS) and atomic force microscope (AFM). The QCM-D results showed that the adsorption amounts of both PAM and HMPAM on model coal surface increased with increasing KCl concentration, and the amount of HMPAM was much higher than that of PAM in 100 mM KCl solution. This result could be due to the fact that the high salinity (e.g., 100 mM KCl) led to the compressed conformation of the polymers and significantly compressed electric double layer repulsion. The conformational changes were determined using MALLS. The AFM force measurement results showed that the adhesion between the polymers and model coal surface increased with increasing the KCl concentrations due to the compressed electric double layer, and the average adhesion of PAM was about one order of magnitude smaller than that of HMPAM. Such difference was mainly ascribed to the hydrophobic attraction between the hydrophobic chain of HMPAM and model coal surface. Meanwhile, the attractive hydrophobic interaction between the hydrophobic chains induced the formation of multiple layers of HMPAM, which was in consistence with the QCM-D results. The fundamental insights into the interaction mechanisms of HMPAM/PAM on model coal surface will benefit the rational development of effective polymer additives for fine coal preparation.
研究领域:
矿物加工工程
·
界面化学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2024
·
IF 5.3
Xiaomin Ma,Pengcheng Wen,Yuping Fan,Wei Sun,Xianshu Dong,Maoqing Yang,Liayong He,Yuanpeng Fu
The objective of this study was to elucidate the cooperative modification mechanism of anionic composite pharmaceuticals on coal substrates. Composite pharmaceuticals were synthesized using sodium hexametaphosphate (SHMP) and sodium polycarboxylate to reduce coal hygroscopicity. The mesoscopic alteration process between the coal surfaces and the compound pharmaceuticals was examined via atomic force microscopy (AFM). AFM showed that SHMP was multilayer-adsorbed on coal via electrostatic and hydrogen bonding, while sodium polycarboxylate was single layer-adsorbed at the SHMP layer via electrostatic interactions. Composite pharmaceutical adhesion to coal was lower than that for individual pharmaceuticals, indicating synergistic effects. The mechanism underpinning the microscopic synergistic effect of complex pharmaceuticals on the coal surface was further examined using density functional theory (DFT) at the molecular scale. DFT calculations showed that the adsorption energy of SHMP binding to a sodium polycarboxylate molecule was greater than that of SHMP binding to two identical pharmaceutical molecules. The SHMP portion generally interacted with the aromatic coal nucleus via its ring structure, exposing the sodium polycarboxylate carbon chain to maximize the adsorption energy. Combining DFT and AFM provided insight into the composite pharmaceutical function, and a theoretical framework for coal flotation separation was established.
研究领域:
材料科学
·
化学工程
·
分子模拟
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Wennan Xu,Yuxin Li,Xin Liu,Yining Zhao,Rui Li,Rui Li,Hongliang Li
Interactions between coal matrix and organics are vital for adsorption [1] , surfactant adsorption on lignite [2] , [3] , [4] , [5] , and solid–liquid separation of coal slurry [6] , [7] , [8] , [9] , [10] . Herein, for studying the interaction between hydrophobic surface (coal surface) and small molecules (organics), we measured interactions between organics [nitro and phenyl , pyridine , phenyl, alkyl chain (hexyl) or cycloalkyl (hexyl)] and the coal matrix (liptinite or inertinite) using atomic force microscopy . The strength of interaction followed the order: nitro and phenyl > pyridine > phenyl > alkyl chain (hexyl) > cycloalkyl (hexyl), and liptinite > inertinite . The liptinite has a greater hydrophobicity than inertinite, the greater the attraction force. The lignite surface and coal slurry were modified in an aqueous solution using five surfactants (dodecyl trimethyl ammonium chloride , DTAC; hexadecyl trimethyl ammonium chloride, CTAC ; octadecyl trimethyl ammonium chloride, STAC; hexadecyl dimethyl benzyl ammonium chloride, HDBAC; and cetyl pyridine chloride, CPC). Subsequently, the moisture adsorption on treated lignite coal surface and the sedimentation of the treated tails was compared to characterize hydrophobic modifications which showed the order of CTAC > HDBAC > DTAC > CPC > STAC. Thus, the interaction between coal surface and organics needs to consider two rules: 1) The desolvation or the hydrophobic property of the coal surface; 2) The VDW force of the organics. The nature of the difference between rules No. 1 and 2 is that with the size of hydrophobic molecules increased to a surface, the H-bond structure between water molecules in the around would change a lot, which formats great hydrophobic property or desolvation. Synopsis Interaction between organic reagents and coal reveals the mechanism of restraining moisture reabsorption of lignite and solid–liquid separation of coal slurry by organics.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
MINERALS ENGINEERING
·
2019
·
IF 3.315
Wenjie Zou,Lu Gong,Jun Huang,Zhijun Zhang,Chunbao Sun,Hongbo Zeng
Selective flocculation separation has been widely used in fine coal flocculation. In order to promote the adsorption selectivity of flocculants onto coal surface, hydrophobically modified polyacrylamide P(AM-NaAA-C 16 DMAAC) was synthesized. The adsorption of P(AM-NaAA-C 16 DMAAC) on model clay and coal surfaces (i.e., silica, alumina and asphaltene surfaces) was investigated using quartz crystal microbalance with dissipation (QCM-D) monitoring technique. Floc size distribution, Fourier transform infrared spectrum, zeta potential measurement and selective flocculation flotation test were also conducted to study the performance of P(AM-NaAA-C 16 DMAAC) in the separation of fine coal. QCM-D measurements showed that a thin and rigid adsorption layer was formed on silica and alumina surfaces after injecting 1 mM sodium hexapolyphosphate (Calgon). This pre-formed layer inhibited the further adsorption of P(AM-NaAA-C 16 DMAAC) on silica and alumina. Meanwhile, the asphaltene surface could not be passivated by calgon due to the weak and reversible adsorption. Thus, a significant amount of P(AM-NaAA-C 16 DMAAC) (20 mg/L) absorbed on the calgon-treated asphaltene surface in 100 mM KCl solution was detected. With 20 mg/L P(AM-NaAA-C 16 DMAAC) in 100 mM KCl and 1 mM calgon solution, the maximum diameters of 10%, 50% and 90% of the cumulative volume distributions of the floc, i.e., d 10 (20.29 μm), d 50 (45.55 μm) and d 90 (89.99 μm) of the coal floc were 7.42, 3.20 and 2.19 times of those of kaolinite floc, respectively. Clean coal with a combustible recovery of 80.87% and ash content of 9.78% was obtained at a dosage of 5 g/t of P(AM-NaAA-C 16 DMAAC) and 900 g/t kerosene. Experimental results demonstrated that selective flocculation flotation with P(AM-NaAA-C 16 DMAAC) could enhance the recovery of fine coal particles with a lower dosage of collector. Our work sheds lights on the fundamental and practical understanding of the hydrophobic interactions in the selective flocculation of coal in the industries, and rational development of flocculants with better selectivity and flocculation efficiency.
研究领域:
化学工程
·
材料科学
·
矿物加工工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2024
·
IF 5.3
Tao Ge,Bingyi Zhou,Jingyao Xu,Yulu Wei
Ionic liquids (ILs) were selected and applied to investigate the best coal desulfurization through orthogonal tests. FTIR, XPS, SEM and contact angle tests were used to characterize the effect on the physical and chemical structures in coal for revealing the coal desulfurization mechanism by ILs-H 2 O 2 system. The orthogonal test results showed that reaction temperature and reaction time were the main influencing factors for the desulfurization rates of coal in the ILs-H 2 O 2 system, and the ILs synergy could effectively improve the desulfurization rates of H 2 O 2 . The maximum coal desulfurization rates of [BMIM][HSO 4 ], [BMIM][OTF], and [BMIM][BF 4 ] ionic liquids were 30.7%, 30%, and 33.2%, respectively. The results indicated that the alkyl groups in coal were oxidized and the contents of oxygen-containing functional groups such as hydroxyl and carbonyl increased. Coal surface underwent swelling, the internal pores increased and new pores and cracks were generated. The wettability of coal improved substantially. In addition, the physical structures changes in coal facilitated the contact between the extractant and the sulfur-containing structures. The contents of thiols and sulfides in coal significantly decreased and were oxidized to sulfoxides and sulfones, with some further oxidized to soluble sulfites or sulfates. Thus achieving removal from coal.
研究领域:
环境科学
·
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）