JOURNAL OF THE ENERGY INSTITUTE
·
2020
·
IF 4.748
Da Zou,Lijun Jin,Mei Zhong,Haoquan Hu,Fengyun Ma
A serials of modified kaolinites were prepared by calcination and further acid treatment and characterized by in-situ XRD, N 2 adsorption, NH 3 -TPD, Py-IR and 27 Al MAS-NMR. And their catalytic performance in pyrolysis of methanol/benzyl phenyl ether (MeOH-BPE), a model compound of low-rank coal, were investigated at 400 °C in a fixed-bed reactor to explore the correlation between the structure of modified samples and their catalytic performances. The results show that calcination temperature above 500 °C causes the collapse of kaolinite structure. Further acid leaching facilitates the formation of micropores and mesopores. The calcination of kaolinite leads to the transformation of six-coordinate Al atoms (Al VI ) into four and five coordinate species (Al IV and Al V ), while the subsequent acid treatment increases the contents of Al IV and Al VI and removes Al V . Total acid sites exhibit a first increase and then decrease tendency with the raising calcination temperature. In the presence of the modified kaolinites, BPE conversion significantly enhances and reaches the highest value of 91.41% over K-A-700 prepared by calcination at 700 °C of kaolinite and further acid leaching. Besides, the maximum content of phenol and toluene is also achieved due to the highest acid sites and Al IV content of K-A-700, which favors the generation of ·H, thus resulting in an obvious inhibition of bibenzyl formation but a significant increase of 2-benzylphenol. In-situ pyrolysis by time-of-flight mass spectrometry suggests that the cleavage of C al -O bond of BPE to form phenol radicals and benzyl radicals is the primary way, while insufficient ·H results in the formation of dominant product of 2-benzylphenol.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Aosheng Yang,Yinfei Liao,Maoyan An,Yijun Cao,Zhe Yang,Hourui Ren,Hailong Su,Qiqi Zou,Luojian Chen
Filter aids are widely used in low-rank coal (LRC) slime filtration. However, their impact on filter cake characteristics is still unclear. In this paper, the effect of anionic polyacrylamide (APAM) and cetyltrimethylammonium bromide (CTAB) on the filter cake characteristics was investigated using Darcy’s filtration theory and low-field nuclear magnetic resonance (L-F NMR). The slime and filtrate property change was determined by contact angle, XPS, FBRM, Zeta potential and surface tension measurements. The results showed that the filter aid improved slime filtration rate and reduced filter cake moisture. The filter aid effect of APAM was better than that of CTAB . CTAB significantly improved the slime surface hydrophobicity with the contact angle increasing to 90.5°, and reduced the filtrate surface tension to 35.26 mN/m. However, APAM decreased the absolute value of slime Zeta potential by 7.48 mV, and increased the slime floc size by about 7–9 µm. Both CTAB and APAM can reduce the filtration resistance, but the effect of APAM was better than that of CTAB, because APAM greatly improved the filter cake permeability. L-F NMR results showed that CTAB increased the filter cake porosity only by 2.65%, while APAM significantly improved the filter cake porosity by 11.65%, especially the mesopore porosity of cake, which increased by 10.48%. It was indicated that CTAB reduced the filtration resistance by “lubricating” the pore wall of the filter cake, while APAM improved the filter cake porosity and permeability by weakening the electrostatic repulsion between slime particles and promoting floc formation through aggregation effect. This research provided a new perspective to reveal the mechanism of LRC slime filtration.
研究领域:
矿物加工工程
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Xicheng Bao,Yaowen Xing,Qinshan Liu,Jincheng Liu,Shiqi Dai,Xiahui Gui,Jihui Li,Zili Yang
Polar and compound collectors are current research hotspots in the field of low-rank coal (LRC) flotation. However, most studies only focus on the collecting ability of collectors while ignoring its selectivity. This study presents the design for a novel high-efficiency ternary compound collector (oleic acid (OA), methyl oleate (MO) and diesel) with great selectivity, strong collecting and spreading ability for Sujiagou LRC. In comparison to diesel, the clean coal yield is increased by 41.40%, and its ash content is reduced by 0.91% at optimal dosage of 2000 g/t. And we propose some new insights on the mechanism of ternary compound collector through density functional theory (DFT) calculations, focused beam reflectance measurement (FBRM), and molecular dynamics (MD) simulations. OA has the strongest collecting ability with the shortest adsorption distance and smallest frontier orbital gap, which ensures the flotation efficiency and collecting ability of ternary compound collector. The great selectivity of ternary compound collector owing to these two reasons: MO adsorbs more strongly on the LRC surface through the flat-lying adsorption at the junction of hydrophilic and hydrophobic parts; the “wasteful adsorption” on the gangue surface is prevented as the nonpolar parts of ternary compound collector attract polar collectors. Finally, a firm oil film with strong spreading ability is formed on the LRC surface, which can achieve a spread across the hydrophilic area even without the adsorption of polar collectors. The synergistic adsorption not only improves the collecting ability of the ternary compound collector but also ensures its selectivity.
研究领域:
化学工程
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材料科学
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环境科学
·
矿业工程
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Fan Lian,Lijun Deng,Guosheng Li,Yijun Cao,Baoxun Zhao,Kai Fan
As the inferior hydrophobicity and low probability of bubble-particle collision, the low-rank coal has poor flotation performance. In this paper, an effective purification method that innovatively combined the use of the microemulsion collector and the CO 2 nanobubbles was proposed. The procedure of the purification method and the reagent regime were established through flotation tests. And the flotation results showed that in the presence of the CO 2 nanobubbles, a satisfactory separation performance with 83.97 % of combustible matter recovery was obtained at a microemulsion collector consumption of 3.5 kg/t. The collector consumption decreased significantly compared with the diesel oil. The interaction mechanism was elucidated through the Zeta potential measurements, the rheological behavior tests, the fractal dimension analysis, and the extended Derjaguin–Landau–Verwey–Overbeek theoretical analysis. On one hand, the microemulsion collectors can reinforce the adsorption of the oily collectors on the low-rank coal surface to improve its hydrophobicity. On the other hand, the agglomeration of the coal particles was strengthened and the probability of bubble-particle collision was increased due to the selective adsorption of CO 2 nanobubbles on the hydrophobically modified surface of the low-rank coal. This research provided new insight into the improvement of the low-rank coal flotation .
研究领域:
矿物加工工程
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
WATER SCIENCE AND TECHNOLOGY
·
2021
·Vol. 84
·期 12
·3726-3737
·
IF 1.915
Wang Penghui,Liu Wenli,Xu Hongxiang,Liu Guowei
An acid modified approach to enhance the adsorption capacity of low-rank coal (lignite) is proposed to reduce the risk of heavy metal ions within the wastewater. Adsorption kinetics, adsorption thermodynamics, adsorption coefficient and density functional theory DFT calculations were studied in this paper, respectively. The results indicate that the adsorption capacity of lignite was enlarged after HNO 3 modification, and pseudo-second order kinetics model and Langmuir isothermal adsorption model can be used to describe the adsorption process. The surface chemical properties of lignite play a dominant role rather than the specific surface area and total pore volume in the Pb(II) cation adsorption process, and it is suggested that the adsorption of Pb(II) cation by raw lignite (RL) and modified lignite (ML) is mainly completed by chemical adsorption. The Fourier transform infrared spectroscopy (FTIR) characterization showed that the surface oxygen functional groups of lignite increased after modification. The results of interaction energies between the model molecule and Pb(II) cation show that Pb(II) cation and -C-O-C are most easily combined, followed by -COOH, and -C = O is the weakest. The adsorption mechanisms of raw and modified lignite and Pb(II) cation were summarized. The original hemidirected structure of Pb(II) cation is broken, and a polar covalent bond is formed. A large number of flocculent precipitates were generated rapidly with the chelating reaction between humic acid molecules and Pb(II) cation. The adsorption of Pb(II) cation by lignite was a chemical adsorption process.
✓ 已验证
DOI
高影响因子
MOLECULES
·
2026
·Vol. 31
·期 17
·2997
·
IF 5.1
Yucong Yun,Rui Sheng,Ting Liu
Owing to the inherent limitations of a single coalification degree, precursors derived from a single-rank coal often struggle to simultaneously fulfill the requirements of composition, structure, and performance. To address this, a blended-coal strategy combining oxygen-rich low-rank Baishihu coal and aromatic-rich high-rank Yicheng coal is proposed to overcome the reactivity–stability trade-off during KOH/KCl activation. The optimized sample, BYCM-40, delivers a high specific surface area of 2556.53 m2·g−1, a hierarchical porosity with 75% micropores and 25% mesopores, and 22.77 at% surface oxygen, achieving a specific capacitance of 357.8 F·g−1and remarkable cycling stability with 99.2% retention after 20,000 cycles. This work is expected to open a sustainable pathway for valorizing low-rank coals into high-performance porous carbons for advanced supercapacitors.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Today Communications
·
2024
·
IF 3.7
Hongwei Fan,Tao Yang
The mechanisms of the effects of decyl polyoxyethylene ether (DEO6), decyl polyoxyethylene ether (DEO8), and aliphatic alcohol polyoxyethylene ether (AEO6) on the wettability of coal dust from low-rank coal have been investigated in this study. The aim is to reveal the difference in the degree of influence of the structure of the alkyl and ethoxy groups. The surface tension test showed that AEO6, which can form a soft chain structure, could reach the critical micelle concentration (CMC) the fastest, followed by DEO6, and DEO8, which has the strongest polar effect, the slowest. The contact angle, settling time, and water retention experiments revealed that the AEO6-treated coal dust had the strongest wettability and water retention, which could effectively inhibit the coal dust and weaken the possibility of its secondary dust. Fourier transform infrared (FTIR) spectroscopy reveals that AEO6 with long alkyl chains can produce strong nonpolar effects, and in the process of adsorption with coal dust, it can produce strong hydrophobic bonding with nonpolar groups on the surface of low-rank coal, and finally form a directional adsorption conducive to the enhancement of wettability. Scanning electron microscope (SEM) showed a trend from DEO6-coal, DEO8-coal, and AEO6-coal appearing to have surfaces that sequentially become flatter and denser, with a gradual decrease in the number of loose particles and a weakening of the pore structure . Molecular dynamics (MD) simulations agree with the above experimental results. That is, the interaction between water molecules is stronger in the AEO6-modified coal system, followed by the DEO8 system and weakest in the DEO6 system. And the advantage of DEO8-coal is weaker than that of AEO6-coal but better than that of DEO6-coal. Based on the above experimental and simulation results, it can be concluded that the ability of the alkyl structure to influence the wettability of surfactant-modified coal dust is higher than the structure of the ethoxylate group, which will provide theoretical guidance for coal dust management and dust suppression.
研究领域:
能源科学
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表面化学
·
环境工程
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Jiaqian Luo,Yulei Li,Yingwei Wang,Baoxun Zhao,Guosheng Li,Lijun Deng,Yijun Cao
Low-rank coal (LRC) exhibits poor floatability due to its porous structure and oxygen-rich surfaces, requiring high doses of ecologically harmful traditional collectors. Understanding coal-reagent interactions is crucial for utilizing green alternatives with targeted interfacial regulation. In this study, an efficient reagent (ADO) composed of ether-based surfactant fatty alcohol polyoxyethylene ether (AEO-9) and diesel oil (DO) is introduced to improve the flotation performance of LRC. Flotation experiments show that ADO significantly outperforms DO, achieving a maximum recovery rate of 95.16 %, representing an increase of more than 30 % compared to DO. Microscopic observations confirm that AEO-9 reduced the collector droplet size from 10.6 μm to 3.35 μm in solution and enhanced its emulsification performance. ADO-modified coal exhibited superior wettability with an increased contact angle and accelerated spreading compared to DO. FTIR and XPS analyses revealed a significant reduction in hydrophilic groups after ADO modification compared to DO, accompanied by an increase in hydrophobic groups. Moreover, charge distribution analysis shows that AEO-9 enhances ADO adsorption on coal surfaces through hydrogen bonding interactions. The adsorption energy of ADO is substantially lower than that of DO. Molecular dynamics results show that the diffusion coefficient of water molecules in the ADO system is 1.930 × 10⁻⁹ m²/s, compared to 2.170 × 10⁻⁹ m²/s in the DO, confirming ADO’s superior ability to enhance the hydrophobicity of low-rank coal surfaces. This study significantly improves the flotation efficiency of LRC by proposing a novel collector with biodegradability and elucidates the mechanism of enhancing flotation performance from a microscopic perspective.
研究领域:
矿物加工工程
·
界面化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
Particuology
·
2024
·
IF 4.1
Shiwei Wang,Yuheng Wang,Rongjie Kong
This study investigates the adverse effects of fine clay minerals on low-rank coal (LRC) flotation. Zeta potential analysis, X-ray photoelectron spectroscopy, flotation experiments, and the particle-bubble attachment index (PBAI) were employed to assess these effects. Results indicate that quartz and chlorite particles are more prevalent in the flotation concentrate than kaolinite and montmorillonite, likely due to their preferential adsorption of flotation collectors, which inhibits the hydrophobicity of the LRC surface. Montmorillonite, however, exhibits greater adhesion to LRC surfaces due to its positive charge. Extended DLVO theoretical analysis reveals that polar surface interaction energy is a primary driving force in coal-mineral interactions and is crucial in overcoming the energy barrier posed by electrostatic double-layer forces. The impact of clay minerals on LRC flotation is highly dependent on clay type.
研究领域:
矿物加工工程
·
界面化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
·
2018
·
IF 3.849
Lijie Wang,Fei Sun,Jihui Gao,Xinxin Pi,Tong Pei,Zhipeng Qie,Guangbo Zhao,Yukun Qin
Focusing on the bottlenecks of traditional physical or chemical activation methods for the preparation of activated carbons, we report a simple and scalable melt infiltration strategy assisted with CO 2 activation for the preparation of activated carbons from Chinese large-scale reserve Zhundong coal. The preparation is achieved by the melt infiltration of a small amount of anhydrous FeCl 3 (10–20 wt%) into the coal framework and subsequent CO 2 -assisted physical activation during which the encapsulated iron species play the dual role of pore-forming templates and activating catalysts. The as-obtained MI-AC-2 possesses a partially hierarchical pore structure with a high specific surface area of 1872 m 2 g −1, five times more than the activated carbon prepared by solely physical activation, which endows the constructed MI-AC-2 electrode with good supercapacitive performances. Relative to the large consumption of activation agents used in a traditional chemical activation process, such a new method with low-cost resource materials and the low-dose FeCl 3 additive paves a scalable way to loading metal precursor into coal/biomass for the preparation of high-porosity activated carbons. This work also provides a simple and efficient strategy to encapsulate active materials into external matrix or substrate.
研究领域:
材料科学
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储能
·
化学工程
·
电化学
✓ 已验证
DOI
高影响因子
International Journal of Mining Science and Technology
·
2023
·
IF 11.8
Fan Lian,Guosheng Li,Yijun Cao,Baoxun Zhao,Guangli Zhu,Kai Fan
As the poor dispersion of oily collectors and the inferior hydrophobicity of the mineral surface, the low-rank coal has an unsatisfactory flotation performance when using traditional collectors. In this paper, an ionic liquid microemulsion was used as a collector to enhance its floatability. Flotation test results demonstrated the microemulsion collector exhibited a superior collecting ability. A satisfactory separation performance of 78.66% combustible material recovery was obtained with the microemulsion collector consumption of 6 kg/t, which was equivalent to the flotation performance of diesel at a dosage of 25 kg/t. The dispersion behavior of the microemulsion collector was investigated using the Cryogenic-Transmission Electron Microscopy. The interaction mechanism of the microemulsion collector on enhancing the low-rank coal flotation was elucidated through the Zeta potential and contact angle measurements, the Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis. The microemulsion collector exhibited superior dispersibility, which was dispersed into positively charged oil droplets with an average size of 160.21 nm in the pulp. Furthermore, the nano-oil droplets could be more efficiently adsorbed on the low-rank coal surface through electrostatic attraction, resulting in the improvement of its hydrophobicity. Thus, the microemulsion collector shows great application potential in improving the flotation performance of low-rank coal.
研究领域:
矿物加工工程
·
界面化学
✓ 已验证
产品关联
DOI
高影响因子
Minerals
·
2023
·Vol. 13
·期 4
·524
·
IF 2.5
Junling Liu,Xicheng Bao,Yesheng Hao,Jincheng Liu,Yulong Cheng,Rui Zhang,Yaowen Xing,Xiahui Gui,Jihui Li,Budeebazar Avid
The compound collector, composed of polar and nonpolar parts, is a current research hotspot in low-rank coal (LRC) flotation because of its outstanding flotation efficiency and cost-effectiveness. However, the selection of compound proportions lacks theoretical guidance. In this study, we comprehensively investigate the internal mechanism underlying the influence of the compound proportion (oleic acid (OA):dodecane (DD)) on LRC flotation. The molecular dynamics (MD) simulation between bubble and oil film was simultaneously employed to study the surface interactions between three phases in contact. The compound proportion of OA:DD = 1:3 was found to be the most conductive for Zhuanlongwan coal flotation, which provides a robust collecting capacity while minimizing excessive interaction with water. Thus, the spreading area is the largest and the interaction energy between collectors and LRC is the highest. Additionally, the oil film formed at this ratio has the best hydrophobicity, resulting in the fastest adhesion speed of the bubble and the most stable bubble adhesion. Proportions of OA:DD above 1:3 promote self-aggregation of polar collectors, leading to a worsened spreading of the oil film. Conversely, proportions below 1:3 result in weak interaction with LRC, leading to a smaller spreading area and reduced hydrophobicity. Ultimately, we propose the LRC–compound collector matching principle, which suggests that the best proportion of compound collectors fits well with the oxygen-containing sites on the LRC surface.Keywords:low-rank coal flotation;compound collector;optimal proportion;MD simulation
研究领域:
矿物加工工程
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）