Effect Of Desorption Research Articles

Study on temperature evolution law of coal containing gas under uniaxial loading process with different loading rates

AbstractIn order to investigate the evolution law of coal temperature during the gestation process of coal and gas outburst, laboratory experiments and numerical simulation approaches were employed. Infrared thermal radiation experiments on the surface of outburst coal during uniaxial loading and failure of coal were conducted. A coal and gas thermal‐hydromechanical coupling model considering the endothermic effect of desorption was established. Numerical simulation of uniaxial loading of gas‐containing coal was implemented to study the influences of deformation energy, frictional heat, and adsorption/desorption endothermic effects on coal temperature. The results indicate that the temperature of coal samples during the uniaxial loading and failure process generally exhibits a stepwise temperature increase. In the initial stage, the elastic thermal effect leads to a slow and fluctuating rise in the temperature of coal samples. During the yield and plastic deformation stages, frictional heat causes a rapid increase in the temperature of coal samples. With the increase of the loading rate, the increment of the temperature of coal samples gradually decreases and reaches the peak when the loading stress is 70% of the peak stress. According to the numerical calculation results, with the increase of the loading rate, the temperature reduction caused by gas desorption relatively decreases. By comparing the experimental results and numerical simulation results, it is found that the temperature reduction caused by desorption is greater than the temperature increments caused by deformation energy and frictional heat. The desorption endothermic effect and frictional heat effect are the dominant factors controlling the temperature variation of coal during the gestation process of outburst. The research achievements have significant theoretical significance and practical value for revealing the temperature evolution mechanism during the gestation process of coal and gas outburst, predicting coal and gas outburst, and protecting the atmospheric environment.

Methane Desorption-Diffusion Behaviors in Micropores of Coal under Different Water Displacement Pressures.

Hydraulic fracturing not only enhances the flow conductivity of coal seams but also transforms the CH4 adsorbed in coal seams into free CH4 and then outputs it via the desorption-diffusion process, thus improving the output quantity and efficiency of CH4. In this paper, taking the coal from Changping mine in Shanxi as the research object, the 3D macromolecule model of coal was established by using analytical test experiments, and the molecular dynamics simulation method of desorption and diffusion was applied to study the characteristics of methane desorption rate and diffusion behaviors under different driving water pressures through the parameters of gas-water concentration distribution, desorption and diffusion rates, and the interaction energies between the coal and the gas-liquid. The results show that the water drive can increase the desorption rate of methane. With the increase of methane adsorption pressure, the desorption effect of water drive becomes stronger and then weaker. The desorption effect of water drive was best when the methane adsorption pressure was 5 MPa and the pressure difference was 2 MPa. Generally, the water drive promoted the methane diffusion, but if the water drive time was too long, it formed a water plug, and the water drive methane inhibited the diffusion. In shallow reservoirs, water drive can obviously promote the desorption-diffusion of methane. The binding energy between CH4 molecules is mainly composed of the repulsive force, while that between water molecules is mainly the adsorption force. In the binding energy between CH4 molecules and coal structures, the van der Waals (VDW) force accounts for 99% of the effect; in the binding energy between water molecules and coal structures, the electrostatic force contributes 84% to ∼88% thereto. The VDW force is significantly influenced by the pressure, while the electrostatic force is slightly affected. As the water displacement differential pressure is increased, the binding energy between CH4 molecules and coal structures decreases.

Enhancing the Regeneration Performance of Methylene Blue Saturated Biochar in H2O2 System via Fe‐Doping

AbstractTo improve the regeneration efficiency of methylene blue (MB) saturated biochar in H2O2 system, biochar was modified by Fe‐doped by using FeSO4 and Fe(NO3)3 as iron sources. The effects of Fe‐doped on its microstructure were characterized by XRD, SEM, and BET. The adsorption and regeneration performance of biochar before and after Fe‐doped were compared through adsorption and regeneration experiments. X‐ray photoelectron spectroscopy, electron spin resonance, and quenching experiments were used to explore the regeneration mechanism. The results show that Fe‐doped biochar (SP‐GBC) prepared from FeSO4 maintains a high specific surface area of 1205.9 m2/g and a high adsorption capacity of 375.43 mg·g−1 for MB. After adsorption, the MB‐saturated SP‐GBC exhibits excellent regeneration performance in the H2O2 system, in which the regeneration efficiencies for five consecutive cycles are 85.76%, 83.92%, 94.01%, 99.24%, and 100.79%, respectively. The synergistic effect of H2O2 desorption and degradation is the main regeneration mechanism for MB‐saturated SP‐GBC. The zero valent iron and Fe (II) on the surface of SP‐GBC are the main active sites for H2O2 activation, while 1O2 and HO· are the main oxidation species. In summary, this work provides a simple and feasible method for the design and synthesis of adsorbents with highly efficient regeneration performance.

Geological controls on distribution of carbon isotope of CBM in Zhengzhuang Block, Qinshui Basin, China

Isotope geochemical experiments were conducted on coalbed methane (CBM) from the Zhengzhuang (ZZ) block to understand its formation history and aggregation pattern in the southern Qingshui Basin. The study analyzed the correlation between methane carbon isotope (δ13C1) and factors such as burial depth, gas content, tectonics, and hydrodynamic conditions in 3# coal seam of the Shanxi Formation and 15# coal seam of the Taiyuan Formation. The findings reveal that the δ13C1 values of CBM in 15# coal seam (average −29.4‰), which is at a greater depth, are slightly higher than those in 3# coal seam (average −30.0‰). Positive correlations were observed between δ13C1, gas content, and burial depth. Variations in tectonic and hydrodynamic conditions between 3# and 15# seams account for differences in the spatial distribution of δ13C1 values. Geochemical data, including drainage water analysis, suggest the presence of a potential hidden structure in the northwestern region. Since the Cenozoic Era, gas reservoirs in the area have undergone restructuring, with δ13C1 influenced mainly by desorption, diffusion, transport, and water-solvation effects. The study's results provide valuable insights for applying CBM δ13C1 data in exploration and production.

Citrus limon peel-based biosynthesis: Lead oxide, zinc oxide, cadmium oxide, and copper oxide nano quantum dots for subtraction of anionic Actas Pink dye (AAPD)

ABSTRACT Adsorption is a highly effective method for wastewater quality adjustment, offering advantages such as low cost and availability of adsorbents. This study investigates the efficient removal of Anionic Actas Pink dye (AAPD), a major contributor to environmental pollution. Green adsorbents including lead oxide (PbO), zinc oxide (ZnO), cadmium oxide (CdO), and copper oxide (CuO) were synthesized via eco-friendly routes for AAPD removal. Maximum adsorption capacities (qe) were observed at pH 7 (PbO, ZnO, CdO) and pH 2 (CuO and native) with values of 83.83 mg/g at 100 ppm, 75.65 mg/g at 100 ppm, 70.50 mg/g 75 ppm, 61.21 mg/g at 150 ppm, and 52.69 mg/g at 150 ppm, respectively, using an adsorbent dose of 0.05 g/50 mL at temperature of 37°C, and 90 min contact time. Adsorption followed Langmuir isotherm for all adsorbents except native, with PbO also fitting Freundlich and Dubinin–Radushkevich isotherms. Kinetics adsorption data supported pseudo-second-order, while thermodynamic analysis indicated spontaneous and exothermic nature. Effects of electrolytes, surfactants, and desorption were also evaluated. Characterization through FTIR, SEM, and XRD confirmed the morphology and functional groups of these nano-quantum dots. Citrus limon peel-based biosynthesis offers sustainable, eco-friendly, and cost-effective alternatives, highlighting their potential for dye adsorption.

A solar-driven hygroscopic aerogel using electrical impedance tomography for exploiting differentiated photothermal interfaces

Photothermal materials and structures are essential for the actual performance of interfacial solar-steam generation systems in atmospheric water harvesting (AWH) technologies. However, the absence of theoretical insights into water desorption, diffusion, and heat transfer at the photothermal interface can impede the development of efficient solar interfacial AWH technologies. To address this gap, we introduce an in-situ imaging approach utilizing the electrical impedance tomography (EIT) system to dynamically visualize the water desorption process within aerogels in real time. The visualization outcomes highlight that the effectiveness of moisture desorption in aerogels is influenced by critical factors, including heat concentration, the localization of heating and cooling, and minimal diffusion resistance. Furthermore, the microstructure and temperature disparities on different sides drive internal water movement and evaporation. The proposed design of the generalized EIT visualization detection system aims to reveal the desorption kinetics of highly efficient solar-driven AWH materials, paving the way for a new frontier in studying the interfacial solar-steam generation process.

Gaseous Nitric Oxide As Probe Molecule for Fe-N-C ORR Electrocatalysts

Iron nitrogen carbon (Fe-N-C) electrocatalysts remain the most promising platinum group metal-free (PGM-free) catalysts for the oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs). Although significant progress has been made in recent years in improving both the ORR activity and stability of the Fe-N-C catalysts, further enhancement in the catalyst durability while maintaining the activity is imperative for the practical applications. One of the major factors that hinders the further enhancement of the catalysts is the lack of clear understanding of the nature of the active sites and density of the active sites in the Fe-N-C catalysts due to the complexity of the Fe-N-C catalysts’ composition and structure. Gaseous nitric oxide was proven to be a suitable probe molecule that can bond to Fe and impede the ORR of the Fe-N-C catalysts. In recent years, we have studied the effects of gas-phase adsorption and desorption of nitric oxide on the redox features and ORR activity on Fe-N-C catalysts synthesized by different methods. We have used various characterization tools to quantify the amount of nitric oxide adsorbed and to identify the adsorption sites and geometry, including electrochemical stripping, temperature programmed desorption, and in situ X-ray techniques. The corresponding results obtained will be summarized in this talk. The implication of these results on the nature of the ORR active sites of the Fe-N-C catalysts will be discussed.AcknowledgementsThis work was supported by the U.S. Department of Energy (DOE), Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office (HFTO) under the auspices of the Electrocatalysis Consortium (ElectroCat 2.0). This work utilized the resources of the Advanced Photon Source, a U.S. DOE Office of Science user facility operated by Argonne National Laboratory for DOE Office. This work was partially authored by Argonne, a U.S. Department of Energy (DOE) Office of Science laboratory operated for DOE by UChicago Argonne, LLC under contract no. DE-AC02-06CH11357.

Inspection for the desorption effect and mechanism of petroleum from contaminated soil in surfactant solution

Inspection for the desorption effect and mechanism of petroleum from contaminated soil in surfactant solution

Arsenate adsorption, desorption, and re-adsorption on Fe–Mn binary oxides: Impact of co-existing ions

Fe–Mn binary oxides have demonstrated impressive arsenate removal efficiencies as adsorbents. However, their interaction with co-existing ions can lead to arsenate desorption, complicating the remediation process. The dynamics of both desorption and subsequent readsorption of arsenate on these oxides under the influence of various ions remain largely unexplored. This study illuminates these processes through a detailed six-month batch experiment, examining the behavior of arsenate in the presence of both single and multiple competing ions. Our findings demonstrate varied desorption impacts by different ions. Notably, the desorption effects induced by bicarbonate (HCO3−) and phosphate (PO43−) were the most significant, with maximum desorption rates reaching 21.8 % and 20.8 %, respectively. Following desorption, As(V) exhibited varying re-adsorption rates; notably, As(V) desorbed by HCO3− and PO43− achieved nearly complete re-adsorption at rates of 100 % and 97.8 % respectively after 150 days. The dynamics altered substantially in the presence of multiple ions. Specifically, the co-presence of Ca2+ and Mg2+ significantly reduced the desorption of As(V) by HCO3−, with maximum desorption rates decreasing to 0 % and 2.9 %, respectively. Moreover, the inclusion of silicate (SiO32−) in the system markedly enhanced the re-adsorption of As(V), surpassing rates observed in the presence of HCO3− alone. In contrast, when PO43−and HCO3− were present together, almost no re-adsorption of As(V) occurred, leading to a higher final desorption rate of 27.4 %. These results highlight the complex and significant role that specific ions and their combinations play in the desorption and re-adsorption of As(V) on Fe–Mn binary oxide surfaces. The study emphasizes the importance of considering the types and interactions of co-existing ions in environmental settings when utilizing Fe–Mn binary oxides for efficient arsenic removal.

Design for Copying Grouser and Bionic Convex Hull Patterns on Track Surfaces of Crawler Combine Harvesters

In the rainy season, which often has uncertain rainfall, crawler combine harvesters have difficulty traversing wet and soft rice fields. A large amount of clay is often accumulated on the track surfaces, resulting in frequent slipping and sinking, which greatly affects the operational performance and harvesting efficiency of crawler combine harvesters. To address this issue, this paper proposes a high-traction track grouser based on the structure of an ostrich’s foot sole. First, a traction force mathematical model is constructed to analyze the interaction between a track grouser and wet and soft rice fields, and parameter optimization is conducted. Then, the bionic information of a dung beetle’s non-smooth body surface is extracted, and the surface of the track is designed with biomimetic convex hull patterns based on the geometric similarity principle and adhesive experiments. Finally, the analysis results indicate that the optimized track grouser significantly improved the traction of the track in wet and soft rice fields. For the track plate with a bionic desorption convex hull pattern, a convex hull diameter of 6 mm, convex hull spacing of 8.25 mm, and convex hull height of 3 mm led to good adhesion reduction and desorption effects in wet and soft soil.

Study on the regeneration of activated carbon adsorbed with radon by using a deep depressurization method

ObjectiveTo develop a heating-free, rapid, and efficient method for the regeneration of activated carbon by introducing deep depressurization. MethodsA validation experimental setup was designed to systematically investigate the impacts of various desorption methods, durations, and conditions on the desorption effectiveness of activated carbon with adsorbed radon and water. Consecutive repetitive and expanded experiments were carried out. ResultsThe combination of continuous ventilation and deep depressurization was proved the most effective in the desorption of activated carbon. Considering factors such as overall energy consumption and time, the optimal desorption duration for activated carbon was determined at 2 ​h. Reducing the relative humidity of radon-laden air and increasing the desorption environmental temperature significantly enhanced the desorption rate. Under a temperature range of 24–25°C, a relative humidity range of 5%–15%, and a flow rate of 0.3 ​L/min, a desorption rate of 85% was achieved for 122.5 ​g of activated carbon after 2 ​h of desorption. Moreover, the desorption results remained stable throughout 10 repetitions. Further experiments on a kilogram-scale activated carbon bed demonstrate that under a vacuum level meeting the requirement for moisture evaporation and an appropriate flow rate, the desorption rate of the activated carbon reached that of a smaller activated carbon bed, independent of the shape of the activated carbon bed. ConclusionThe deep depressurization method shows great promise as a rapid and efficient online method for the regeneration of activated carbon with adsorbed radon and water.

Treatment of Water Contaminated by Ship Oil: Study of Adsorption in a Fixed-Bed Column

Aquatic macrophytes like Salvinia sp. have rapid proliferation and a great capacity for ecological adaptation. In addition to these characteristics, this study points to their ability to adsorb contaminants such as dyes, metals, and oils. This work aims, through an adsorption study, to propose an alternative treatment using chemically modified Salvinia sp. (SOH) biomass to remove oil from water. Batch adsorption experiments were performed to observe the effects of concentration, pH, time, temperature, desorption, and reuse of the biomass. The adsorption mechanisms, performance, kinetics, isotherm, thermodynamics, and reusability of biomass were evaluated. Both adsorbents were well-defined by the Freundlich model isotherm. According to the results obtained, the qmax was 898.0 mg g−1 for SOH in oil-in-salt water emulsion in 15 min and 930.59 mg g−1 for Salvinia sp. in natura (SS) in the oil-in-water emulsion. In the fixed-bed column adsorption, the adsorption capacity was 2.99 g g−1 for SS and 3.49 g g−1 for SOH, and the saturation capacity was 42.89 g g−1 SS and 42.99 g g−1 SOH. According to the adsorption models, the Bohart–Adams model best fits the experimental data of this study. The SOH adsorbed oil recovery test was successful, with 100% oil recovery.

Facile synthesis of amine hybrid silica aerogel globule via wet casting assisted self-catalysed sol-gel process for CO2 capture including direct air capture

Amine hybrid silica aerogel globule (AHSAG) for CO2 capture including direct air capture (DAC) was firstly synthesized via wet casting assisted self-catalyzed sol-gel process. AHSAG has abundant interpenetrating macropores, which favors diffusion of CO2 into internal amine sites and can enhance CO2 adsorption kinetics and capacity. The optimal CO2 adsorption capacity of AHSAG with dry 100% and 400 ppm CO2 are 3.82 (30 °C) and 1.86 mmol/g (55 °C), respectively. Corresponding amine efficiencies are 0.478 and 0.233. The effect of temperature on CO2 adsorption capacity is attributed to simultaneous enhancement of mass transfer kinetics and adsorption thermodynamics. The highest CO2 adsorption rate of AHSAG is achieved at 70 and 55 °C with 100% and 400 ppm CO2, respectively. The trend of CO2 adsorption rate with temperature is attributed to the synergistic effect of diffusion kinetics and desorption. Based on experimental CO2 adsorption kinetics, adsorption mechanism in 400 ppm CO2 was estimated with different diffusion models. Both film diffusion resistance and intraparticle diffusion resistance are involved in CO2 capture of AHSAG from air under given condition to control the overall adsorption process. Three kinetics models were used to fit the experimental data of AHSAG for DAC, and the Avrami model showed the best fitting within the whole adsorption period. Comparing with its state-of-the-art counterparts, AHSAG offers significant advantages for practical DAC, such as high adsorption capacity and amine efficiency, fast adsorption kinetics, and excellent cyclic stability.

EDTA-interlayer modified Mg/Fe layered double hydroxides for enhanced adsorption of methyl orange: Adsorption performance and mechanism study

Herein, we explored the efficacy of ethylenediaminetetraacetic acid (EDTA) intercalation modified layered double hydroxides (LDHs) composites for removing the anionic dye methyl orange (MO) from aqueous solutions. EDTA intercalated layered hydroxides (EDTA-Mg/Fe LDHs) with a 4:1 Mg/Fe molar ratio have been successfully prepared and thoroughly characterized using SEM-EDS, FTIR, XRD, XPS, UV-Vis and Zeta potential analysis. Batch adsorption experiments were conducted to evaluate the adsorption performance of the innovative adsorbent on MO. The results indicated successful EDTA loading into Mg/Fe LDHs, exhibiting excellent adsorption performance for MO. At pH 6.0, with a 0.03 g adsorbent dose, MO removal exceeded 91.10% within 90 min, following a pseudo second order kinetic model. The maximum adsorption capacity reached 1207.43 mg/g, fitting well with the Redlich Peterson model. Thermodynamic parameters suggested a spontaneous and favorable adsorption process. Furthermore, we assessed the desorption and regeneration effectiveness of EDTA-Mg/Fe LDHs, emphasizing the importance of developing cost-effective and environmentally friendly adsorbents with practical applications and scientific significance.

Simulation and Structural Analysis of a Flexible Coupling Bionic Desorption Mechanism Based on the Engineering Discrete Element Method.

Soil adhesion is one of the important factors affecting the working stability and quality of agricultural machinery. The application of bionic non-smooth surfaces provides a novel idea for soil anti-adhesion. The parameters of sandy loam with 21% moisture content were calibrated by the Engineering Discrete Element Method (EDEM). The final simulated soil repose angle was highly consistent with the measured soil repose angle, and the obtained regression equation of the soil repose angle provides a numerical reference for the parameter calibration of different soils. By simulating the sinusoidal swing of a sandfish, it was found that the contact interface shows the phenomenon of stress concentration and periodic change, which reflects the effectiveness of flexible desorption and soil anti-adhesion. The moving resistance of the wedge with different wedge angles and different serrated structures was simulated. Finally, it was found that a 40° wedge with a high-tail sparse staggered serrated structure on the surface has the best drag reduction effect, and the drag reduction is about 10.73%.

Sabatier effect based adsorption-desorption coordination via cationized chitosan for enhancing ion kinetics in zinc anodes

Interface engineering through a Sabatier effect-based adsorption–desorption coordination via cationized chitosan offers a promising approach to counteract dendritic growth, hydrogen evolution, and sluggish Zn2+ kinetics. The adsorption effect in zinc ion batteries is important for maintaining a balanced distribution of zinc ions and reducing dendrite formation. However, an excessive emphasis on the adsorption effect often neglects the desorption process of zinc ions, leading to a decrease in overall ion reaction kinetics. Herein, an adsorption–desorption synergic coating called CGP@Zn was systematically designed on zinc anodes to serve as both a Zn2+ adsorption and desorption regulator and a functional protective interface. The CGP@Zn coating exhibited zincophilic and negatively charged amino and hydroxy functional groups, which facilitated the transport of Zn2+ ions and repelled free SO42- anions. Moreover, the positively charged N+ component of the CGP@Zn coating exhibited a strong desorption effect, guaranteeing the voluble retransfer of Zn2+ and promoting intensive kinetics. Collaborating with the functional interface layer, the CGP@Zn anode demonstrated a significantly high ionic transfer number of 0.72. Furthermore, CGP@Zn symmetrical cells showed an impressive ultralong lifespan of over 5000 h with an extremely low polarization voltage of ≈80 mV at 1 mA cm−2 and 2 mAh cm−2. More encouragingly, the MnO2-based full batteries endowed with the CGP interface layer achieved a capacity of 206 mAh g -1 with a retention of 91.8 % over 500 cycles at 1C. This study offers a new perspective for designing high-performance aqueous batteries via coordination of adsorption–desorption.

Synthesis of polyacrylate-divinylbenzene hydroxamic resins and its gallium adsorption performance in sulfuric acid solution

In this study, the adsorption behavior of gallium ions on a synthesized hydroxamic acid resin from sulfuric acid solution was investigated, aiming to recover Ga directly from pressure leaching solution in zinc hydrometallurgical plant. Hydroxamic acid chelating resin (HA-PDR) was prepared by introducing hydroxamic acid groups into the pre-made polyacrylate resin (PDR) with methyl ester group through hydroxylamine reaction. Polyacrylate-divinylbenzene hydroxamic resins with a nitrogen content of up to 3.85 % were obtained at a divinylbenzene (DVB) content of 13 % and an optimal raw material ratio of NH2OH·HCl: NaOH: −CH3 = 4:4.5:1 (molar ratio). The obtained materials was characterized using FTIR, XPS and SEM to verify the successful introduction of hydroxamic acid groups. The results of adsorption experiments showed that the adsorption capacity of 27.65 mg/g could be obtained with a chemical, multilayered, and heterogeneous adsorption process, and film diffusion and intra-particle diffusion rate controlled mainly the adsorption efficiency. It has been proven that polyacrylate-divinylbenzene hydroxamic resins has extremely high adsorption selectivity for gallium in sulfuric acid solution, and the desorption effect is obvious, which can be applied promisingly in the industrial development of gallium extraction technology from zinc leaching residue in sulfuric acid system.

Characteristics of Acid Leaching and Vibration Coupling Desorption of Gas-Saturated Coking Coal.

Permeability is a key factor affecting efficient gas drainage from coal seams, and acidification and vibration shock are effective means to increase permeability in original low-permeability coal seams. To study the gas desorption characteristics of coking coal under the coupling effect of mining disturbance and acidification permeability enhancement, taking the coal seam of Shoushan No. 1 coal as the research object, a self-built adsorption-desorption vibration test platform was used. Acid leaching vibration coupling desorption experiments at vibration frequencies of 0, 30, 60, and 100 Hz were conducted on selected particle coals with particle sizes of 0.18-0.25 and 1-3 mm. The experimental results show that the gas desorption amount of particle coal with the same particle size first increases and then decreases with the increase of vibration frequency, among which the desorption effect is the best under 60 Hz vibration condition. Under the condition of fixed vibration frequency, the desorption amount, initial desorption velocity, and velocity attenuation coefficient of particle coal increase as the particle size decreases. Under the same particle size and vibration frequency conditions, the acid leaching and vibration of coal samples have a synergistic effect on gas desorption, which is manifested in the promotion of gas desorption on the outer surface of the coal sample and the surface of open macropores. The research can provide theoretical reference for coal seam acidification and permeability enhancement under the influence of mining disturbance.

Study on the kinetic characteristics and control steps of gas production in coal spontaneous combustion under the oxidation path

The low-temperature oxidation of coal involves multiple gas production paths including desorption, pyrolysis and oxidation. These paths interfere with each other, resulting in unclear kinetic characteristics of CO and CO2 production in coal oxidation and incomplete mechanism of gas production. Therefore, this paper proposed a method that can effectively exclude the effects of desorption and pyrolysis on gas production and adopted this method to explore the kinetic characteristics of CO and CO2 production under different paths. Besides, with the aid of microscopic characterization methods, the kinetic steps controlling gas production and the mechanism of gas production were analyzed. The experimental results demonstrate that the proposed method can effectively eliminate the effects of desorption and pyrolysis, and can obtain the kinetic characteristics of gas production under the oxidation path that can reflect the intrinsic characteristics of low-temperature oxidation of coal. Based on the difference method, the activation energies of CO and CO2 produced under the oxidation path are 59.49 kJ/mol and 60.09 kJ/mol, which activation energies are almost the same, suggesting that CO and CO2 are likely to be produced from the same precursor. The gas production in low-temperature oxidation is a process in which methylene groups in coal react with oxygen to generate oxygen-containing intermediates which then decompose to produce CO and CO2. The reaction of methylene groups with oxygen is the control step of gas production kinetics in coal spontaneous combustion, resulting in the same apparent activation energies of CO and CO2 production in the stable phase under the oxidation path.

Study on regeneration characteristics of granular activated carbon using ultrasonic and thermal methods.

Dye wastewater is a type of high-concentration, high chromaticity, and high salinity organic wastewater, which is generally treated with activated carbon adsorbent. The effective regeneration of granular activated carbon (GAC) is the key to reducing the operating cost of GAC in the wastewater treatment process. The regeneration characteristics of saturated GAC adsorbed on 288 orange dye wastewater were studied by using the ultrasonic coupled thermal regeneration method. The results showed that the regeneration efficiency of GAC adsorbed on 288 orange dye wastewater increased with the increase of ultrasound power. The optimal ultrasound frequency and regeneration temperature were determined to be 45kHz and 60 ℃, and the relationship between regeneration times and carbon loss rate was explored. The combination of ultrasound and high-temperature heating methods has successfully improved the regeneration efficiency of GAC and significantly reduced the high-temperature thermal regeneration time of GAC, thereby reducing the mass loss rate of GAC. The performance changes of fresh activated carbon (FAC), saturated activated carbon (SAC), ultrasonic regeneration of activated carbon (UAC), and thermal regeneration of activated carbon (TAC) during the combined regeneration process were explored by characterizing the regenerated GAC. Infrared characterization showed that the C-O group of GAC was significantly weakened after coupling treatment, indicating that ultrasonic treatment can significantly enhance the desorption effect of thermal regeneration. The microjet, shock wave, and cavitation effects generated by ultrasonic treatment restore the specific surface area of GAC, mainly increasing the micropore volume and pore size of GAC, and enhancing the treatment effect of thermal regeneration.