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The effective activation of persulfate relies on the excellent porosity and active sites of carbon materials, which play a pivotal role in catalytic performance during water treatment. In this study, a porous iron-carbon composite material (Fe-RC) was synthesized from coal gasification fine slag (CGFS) through an impregnation-calcination method for rhodamine B (RhB) removal in a peroxydisulfate (PDS) system. Fe-RC demonstrated outstanding catalytic performance, achieving a RhB removal rate of 99.9 % and a kinetic reaction rate of 0.0232 min−1. Characterization revealed that Fe-RC possessed a specific surface area of 476.93 m2·g−1 with abundant microporous (30.89 %) and mesoporous (62.56 %) structures, providing a solid foundation for effective RhB removal. X-ray photoelectron spectroscopy analysis indicated that functional groups (C-O) and loaded iron species were primarily responsible for the generation of reactive oxygen species (SO 4 •−, •OH, and O 2 •−). Moreover, electrochemical analyses demonstrated the significant impact of electron transfer on RhB removal. The loading of iron species enhanced the electron transfer capability of the composites, facilitating the extraction of electrons from RhB, and promoting RhB degradation through the non-radical pathway. Thus, Fe-RC derived from coal gasification slag is a potential catalytic material for efficient PDS activation, offering novel perspectives on the utilization of catalytic materials derived from CGFS and the high-value utilization of CGFS. [Display omitted] • A highly efficient and economical catalyst (Fe-RC) was synthesized from CGFS. • The great adsorption capacity of Fe-RC was a key step for the catalytic process. • Fe-RC had excellent cycling and universal properties. • Fe species and C-O on the composite caused the generation of free radicals. • The electron transfer dominated in the non-radical pathway rather than 1O 2. [ABSTRACT FROM AUTHOR]

Abstract Using lignite as an adsorbent and subsequently as a material for coal water slurry (CWS) preparation represents an alternative method for coal chemical wastewater treatment. However, the components in these wastewaters could affect the CWS performance, especially ammonia nitrogen (NH 4 +-N). The influencing mechanism of NH 4 +-N was studied through adsorption method. Associated with adsorption reaction model, Fourier transform infrared spectrum and zeta potential detection, it was found that the adsorption reaction of NH 4 +-N, driven by ion-exchange interactions with H+ of –OH and –COOH on the lignite surface, displayed a typical monolayer mode and was much faster than that of NSF which displayed a double-layer mode and was adsorbed preferentially at hydrophobic sites. In binary adsorption, the adsorption amount of NSF was increased remarkably by adding NH 4 +-N. This was attributed to the modified lignite surface and hydrophilic group by NH 4 +-N that decreased the surface electronegativity as well as the electrostatic repulsion among –SO 3 − in NSF molecules. The enhanced adsorption of NSF resulted in capturing more water molecules in hydration film surrounding the particles in CWS. The hydration film was then thickened and stabilized, thus leading to a decrease in free water for CWS flowing. As a result, the apparent viscosity was increased, and CWS tended to be dilatant. In addition, the thickened and stabilized hydration film also increased the yield stress of CWS prepared with NH 4 +-N, resulting in improved stability. [ABSTRACT FROM AUTHOR]

The conversion of coal gasification wastewater into coal wastewater slurry (CWWS) for combustion and gasification fuels is a promising approach that combines resource recovery with effective wastewater management. In this work, the influence of organic ingredients derived from coal gasification wastewater on the slurrying capabilities of lignite, particle dispersion/aggregation behavior, and adsorption characteristics between lignite and sodium methylene dinaphthalene sulfonate (NNO) in CWWS was thoroughly investigated. The interaction mechanism of lignite, NNO, and the organic ingredients in the slurry systems revealed subsequently by molecular dynamics (MD) simulations. Results indicated that the maximum solid concentration for coal gasification wastewater simulated by organic ingredients increased by 1.64% with a decrease in pseudo-plasticity and stability. The presence of dodecane, phenolic and heterocyclic nitrogen compounds caused the dissociation and coalescence of particles in the CWWS and further formation of creaming or clarifying layer. The adsorption processes of NNO and the organic ingredients on lignite particles exhibited competitive adsorption, following the pseudo-second-order kinetic and the Freundlich thermodynamic models. The adsorbed organic ingredients enhanced the hydrophobicity and electrostatic repulsion of the particle surface in CWWS, increasing the hydrophobic C-C/C-H content from 64.73% to 71.27%. Moreover, the MD simulation results revealed that the adsorption conformations at the lignite-water interface in CWWS changed from "single-point and single-layer" adsorption of NNO to "multi-point and multi-layer" adsorption of NNO and organic ingredients driven by hydrophobic effect, van der Waals force, π-π stacking effect, and hydrogen bonding. [Display omitted] • The adsorption of organic pollutants on lignite surface driven by intermolecular forces. • Established the correlation between organic pollutants and particle aggregation/dispersion. • Competitive adsorption existed between NNO and organic pollutants in CWWS. • MD simulation revealed the atomic-scale details of the co-slurrying mechanism. [ABSTRACT FROM AUTHOR]

The pore structure of Xilingol lignite irradiated by microwave was investigated to determine drying time, microwave power level, and mineral composition. Pore structure was also determined using N 2 adsorption/desorption as well as scanning electric microscopy. The results show that as microwave power increases from 400 W to 800 W, and irradiation time increases from 4 to 16 min, the specific surface area of lignite samples increases, average pore diameter and total pore volume decreases, and the percentage of mesopores increases. The pore volumes, average pore diameters, and special surface area in the center of the lignite sample were greater than those in the outer layers, while the percentage of mesopores decreased slightly. The cluster structure of the lignite samples is simpler and the surface neater, while flat and fibrous structures remain the same. Evolution mechanisms for pore structures during microwave drying were similar, and include structural collapse caused by shrinkage forces resulting from the removal of moisture, the opening and crosslinking of blind and closed pores, and the thermal decomposition of organic macromolecular structures under high temperatures. [ABSTRACT FROM AUTHOR]

A newly designed two-grade fractal model for improving the packing state in brown coal water slurry (BCWS), which was built on the fractal theory and modified by separating the size into two grades, was investigated systematically. Packing efficiency (PE) and regression levels of the fractal model in various particle systems were analyzed. The results showed that the PE of brown coal particle system is determined mainly by the fractal characteristics of particles under 74 μm and the packing state in BCWS can be significantly improved when the fractal dimension is around 2.6–2.7. In addition, the two-grade fractal model fits the PSDs for various particle systems with different graduation ratios of coarse samples (CS), fine samples (FS) and ultra-fine samples (UFS) well. PE reaches the maximum value when the graduation ratio is 7:0:3 (CS:FS:UFS) and the fractal dimension is 2.7080, which is consistent with the calculated results. It was confirmed by the slurry preparation experiment that the maximum solid loading of BCWS increased by 2.9% through optimizing the packing state using two-grade fractal model. [ABSTRACT FROM AUTHOR]

The preparation of hierarchical porous silica aerogels from coal gasification fine slag (CGFS) offers an effective approach to achieving high-value utilization of solid waste and reducing the production cost of solid adsorbent matrix materials. However, the main challenges involve overcoming technical barriers to efficiently and value-added conversion of CGFS into silica aerogels with CO₂ adsorption properties, as well as elucidating the phase transformation mechanisms during the synthesis process. In this study, CGFS was used as the raw material to obtain a silicon-containing precursor through pre-decarbonization (with ash content as high as 99.82 %) and alkali dissolution treatment. A hierarchical porous silica aerogel was then synthesized using an efficient hydrothermal process. The effect of alkali dissolution on silicon extraction and the phase transformation mechanisms were thoroughly discussed, and the leaching mechanism was analyzed through thermodynamic and kinetic models. The results showed that the high leaching rate of silicon was attributed to the presence of a large amount of amorphous SiO₂ in the decarbonized fine slag (DCFS), while the formation of zeolite Na-P1 and hydroxysodalite during the alkali dissolution process affected the efficiency of silicon extraction. Then, the structural formation mechanism and CO₂ adsorption properties of the hierarchical porous silica aerogels were analyzed using N₂ adsorption-desorption and CO₂-TPD. The SiO₂-1-30-0.5 exhibited a high CO₂ adsorption ability of 1.53 mmol g−1, and the CO₂ adsorption capacity maintained 94.78 % of the original value and after 5 adsorption-desorption cycles. [Display omitted] • Hierarchical porous silica aerogels were efficiently synthesized using DCFS. • The phase transformation and silicon leaching mechanism during the alkali dissolution process of DCFS were revealed. • The structural formation mechanism and CO 2 adsorption properties of hierarchical porous silica aerogels were studied. • The sample showed CO 2 adsorption capacities of 1.53 mmol g−1 at 273K. [ABSTRACT FROM AUTHOR]

Coal gasification fine slag is a solid waste of difficult-to-separate nature. In this study, the residual carbon was enriched from fine slag by conventional flotation. The optimal flotation results in the concentrates yield of 59.01%, the concentrates ash content of 37.64%, and the flotation perfect index of 41.12%, respectively. Under the identical conditions, step release flotation exhibits abnormal results, i.e., the lowest ash content is concentrates 3 (C 3) corresponding to 29.21%. The particle distribution analysis of concentrates 1 (C 1) to concentrates 5 (C 5) and tailings (T) shows that particles of the highest carbon content transfer to C 3 , while dominated by ash are enriched in T. Additionally , the particle structure characteristics (with SEM, BET surface area, BJH pore volume/average pore width, FHH fractal characteristics) demonstrate that the particles differ in pore's volume, average width, and interior smoothness. This concludes that it is the larger pore volume, the wider average pore width, and the smoother pore interior that contributes to the greater amount of diesel adsorption and therefore easier release of carbon-content particles in flotation. Such regularities of particle transfer in flotation and release mechanism manifest the flotation specificities of gasification fine slag, which may provide a scientific reference for effectively enriching residual carbon in coal gasification fine slag. [Display omitted] • Conventional flotation upgrades coal gasification fine slag with η as 41.12%. • Concentrates 3 (C 3) abnormally contains the lowest ash content of 29.21%. • Analysis of particle distribution reveals regularities of particle transfer. • Particle structure study learned the release mechanisms of particles. • Flotation specificities of coal gasification fine slag were clarified. [ABSTRACT FROM AUTHOR]

• Entrained-flow gasification coal fine slag can be upgraded by ultrasonic flotation. • Ultrasonic flotation perfect index (η) is 12.60% higher than conventional flotation. • The ash content of ultrasonic flotation concentrates is as low as 27.11%. • Ultrasonic emulsification improved the stability of bubbles in flotation. Entrained-flow gasification coal fine slag is a low value and difficult-to-separate solid waste. In this work, ultrasonic flotation experiments are adopted to enrich the residual carbon and are compared to conventional flotation. The concentrate yield and concentrate ash content decrease by 9.94% and 16.54%, respectively, with the flotation perfect index 12.60% higher. Scanning electron microscopy/energy-dispersive X-ray spectroscopy and thermogravimetric analysis show that the ultrasonic flotation has a positive effect on the residual carbon enrichment. Furthermore, the wet screening results prove that the ultrasonic flotation has a more significant crushing effect on the entrained-flow gasification coal fine slag particles than conventional flotation, mainly benefitting the flotation of small particles (i.e. 0.15–0 mm size fractions). Moreover, after ultrasonic emulsification, the collector can be dispersed more evenly and the surface tension of the collector-deionized water system is decreased, which is beneficial to improving the selectivity of the collector. In addition, with ultrasonic pretreatment at 180 W for 4 min in pulp and emulsification at 180 W for 20 s in the collector-deionized water system, the bubbles in the froth layer are the smallest and most stable, and the merging of the bubbles becomes less obvious. [ABSTRACT FROM AUTHOR]

A Rh(III)-catalyzed C–H activation-desymmetrization of diazabicycles with o -vinylphenols as an efficient approach to alkenyl-substituted aminocyclopentenes is reported. This protocol represents another classic example for direct C–H activation of terminal alkenes using enol as directing group. The reaction features the ease of the preparation of starting materials, fast and high efficiency, broad substrate scope and 100% atom economy, thus provides a valuable entry to synthesize novel substituted cyclopentenes. [ABSTRACT FROM AUTHOR]

[Display omitted] • CGW from a typical airflow bed was investigated for closed water circulation. • The clarified layer was due to organics while sediment layer was NH 4 + and Ca2+. • CGW components reduced the wettability, Zeta potential and porosity of particles. • Competitive adsorption existed between NNO and organics with benzene ring in CWWS. • Cations reduced the hydrophobic and electrostatic repulsion energies of particles. Coal gasification wastewater (CGW) as a substitute for clean water to prepare coal water slurry, which serves as gasification/combustion feedstock, can simultaneously achieve wastewater management and resource utilization. The purpose of this work was to investigate the effects of internal components (i.e., oils, phenols, nitrogen heterocyclic compounds, and inorganic cations) in CGW on the slurryability and dispersion/aggregation behavior of lignite and their co-slurrying mechanisms through experimental and the extended DLVO (eDLVO) theoretical calculations. Results showed that compared to lignite water slurry (LWS), the maximum solids concentration (ω max) of coal gasification wastewater slurry (CWWS) increased by 0.80%, with a lower pseudo-plasticity. The organic compounds adsorbed competitively on the hydrophobic regions of lignite improved the slurrying capability of CWWS by decreasing the wettability, Zeta potential, roughness and pore structure of the particles. By contrast, the static stability of CWWS decreased, and its kinetic stability index (TSI) increased from 0.23 to 0.33. From the backscattering spectra, dodecane caused the creaming process of the slurry, while the clarification process was attributed to phenol and nitrogen heterocyclic compounds. Inorganic cations, especially NH 4 + and Ca2+, significantly reduced the hydrophilic and negative charges on the particle surface, which were the main unfavorable factors leading to particle aggregation and sedimentation. The eDLVO theoretical calculation results exhibited that inter-particle interaction in CWWS was determined by the hydrophobic energy (E h) and electrostatic energy (E e) and their dropped from 1.79 × 10−16 J and 5.16 × 10−17 J to −4.67 × 10−16 J and 2.59 × 10−17 J respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • The slurryability of the mixed slurry was facilitated most with the lignite/DCLR mass ratio of 5:5. • The maximum solid concentration of the mixed slurry increased from 41.70 wt% to 53.91 wt%. • The combustion process of the mixed slurry was more concentrated and violent. • The DCLR promoted organic pollutant emissions in the wavenumber range of 1500–500 cm−1. • Except for Pb and Zn, more than 85% of Cr, Cu, and Ni were intercepted in solid residues. Direct coal liquefaction residue (DCLR) as an auxiliary feed material with lignite to prepare coal water slurry (CWS), which is then used as combustion fuels, enables recycle resources of DCLR and diminishes its impact on the surrounding environment. This paper aims to study the slurryability, combustion characteristics, and typical pollutant emissions of the lignite water slurry (LWS), DCLR water slurry (DCLRWS), and lignite-DCLR water slurry (L-DWS). Results showed that the DCLR and lignite were complementary in physicochemical properties for preparing the L-DWSs. The maximum solid concentration (ω max) of the DCLR was 73.19 wt% with poor static stability, whereas that of the LWS was 41.70 wt% with high pseudoplasticity. By contrast, the ω max of the L-DWS-5 prepared from the lignite and DCLR at mass ratio of 5:5 was 53.91 wt% with lower pseudoplasticity and static stability. Meanwhile, combustion experiments confirmed that the introduced DCLR was effective in improving the ignition, burnout, and comprehensive combustion performance of the L-DWS. The Q net, p of the slurrying samples increased from 6.70 MJ/Kg for the LWS to 14.41 MJ/Kg for the L-DWS-5. And the addition of the DCLR exhibited slight influences on the emissions of NOx and SO 2 , but significantly increased HCN and other organic compounds such as C n H m , CO, and NH 3 emissions. Furthermore, except for Pb and Zn, more than 85% Cr, Cu, and Ni were intercepted in solid residues. [ABSTRACT FROM AUTHOR]

To effectively and cleanly handle the direct coal liquefaction residue (DCLR), a two-phase microwave reaction system was designed based on poly-generation lignite technology, that performed both individual pyrolysis and co-pyrolysis, to investigate the effect of microwave co-pyrolysis of lignite with different addition of DCLR on the pyrolysis products characteristics. The experimental results demonstrated the presence of synergism during microwave co-pyrolysis, which enhanced the condensation reaction of different free radicals, and thus increased the char (upgraded lignite, UL) yield by 6.14–10.42%. The DCLR showed excellent catalytic effects as consumable absorbents in terms of heating rate, and char and gas yields, and it eventually converted into high value-added combustible gases (CO, CH 4 , and H 2). Furthermore, when compared to the individual pyrolysis sample and lignite, the co-pyrolysis samples' chemical structures were progressively aromatized, and exhibited significantly lower O/C ratios, re-adsorption moisture content, and reactive groups and available sites. Moreover, the pore structures on the surface for the co-pyrolysis samples were dominated by cracks, blowholes, and open-ended fissures, which gradually decreased as DCLR contents increased. Combustion behavior and kinetic analysis confirmed that microwave co-pyrolysis changed activation energy (E a) distribution of ULs and thus improving their combustion performance. Therefore, microwave co-pyrolysis of lignite with DCLR was an effective and economical approach for clean utilization DCLR and obtaining high-quality lignite fuel. • Combined lignite upgrading and clean utilization DCLR via microwave co-pyrolysis. • Synergistic effects between lignite and DCLR increased char yield by 6.14–10.42%. • The highest thermal effect was obtained when lignite was mixed with 15 wt% DCLR. • The DCLR intensified the chemical structure's evolution while reducing the porosity. • Lignite after co-pyrolysis exhibited difficulty in igniting, but combusted easily. [ABSTRACT FROM AUTHOR]

As the composition of direct coal liquefaction residue (DCLR) is complex and difficult to handle, more importantly its dielectric properties are excellent, it is used as consumable wave-absorbents to enhance the microwave pyrolysis of lignite for slurryability improvement. The effects of the different additions of DCLR on the evolution of pyrolysis products were studied by using gas chromatography, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and low-temperature N 2 adsorption analysis. The results indicated that microwave-assisted pyrolysis with DCLR was a promising method for improving slurryability of lignite and an effective method for utilizing DCLR. The introduced DCLR accelerated the heating rate of the process of microwave upgrading lignite, facilitating the decomposition of active oxygen-containing functional groups and aliphatic hydrocarbons and then their transformation into stable ether groups and aromatic structures. In the meantime, it was converted into gaseous products, mainly composed of H 2 , CO, and CH 4 , and solid products with high quality. Additionally, the cyclization and aromatization of organic structures were improved, as well as the order degree of aromatic systems, especially with 12 wt% of DCLR added. Furthermore, the existing and newly formed structures of micropores and mesopores in the upgraded lignite (UL) were remarkably reduced with the increase of DCLR contents. The re-absorption capacity was dramatically reduced and the slurryability of UL was improved as a result of the changes in chemical properties and pore structures. The maximum solid concentration of lignite water slurry (LWS) increased from 41.73 wt% to 65.42 wt% with lower pseudo-plasticity and static stability. • Direct coal liquefaction residue was used as consumable microwave absorbent. • The absorbent was eventually converted into gases with highly added value. • Infrared and Roman parameters were combined to reflect the char structure. • The absorbent promoted aromatization of organic structure while reduced porosity. • The maximum solid concentration of lignite water slurry reached 65.42 wt%. [ABSTRACT FROM AUTHOR]