Effect Of Desorption Research Articles

Sulfur Migration Enhanced Proton-Coupled Electron Transfer for Efficient CO2 Desorption with Core-Shelled C@Mn3O4.

Transforming hazardous species into active sites by ingenious material design was a promising and positive strategy to improve catalytic reactions in industrial applications. To synergistically address the issue of sluggish CO2 desorption kinetics and SO2-poisoning solvent of amine scrubbing, we propose a novel method for preparing a high-performance core-shell C@Mn3O4 catalyst for heterogeneous sulfur migration and in situ reconstruction to active -SO3H groups, and thus inducing an enhanced proton-coupled electron transfer (PCET) effect for CO2 desorption. As anticipated, the rate of CO2 desorption increases significantly, by 255%, when SO2 is introduced. On a bench scale, dynamic CO2 capture experiments reveal that the catalytic regeneration heat duty of SO2-poisoned solvent experiences a 32% reduction compared to the blank case, while the durability of the catalyst is confirmed. Thus, the enhanced PCET of C@Mn3O4, facilitated by sulfur migration and simultaneous transformation, effectively improves the SO2 resistance and regeneration efficiency of amine solvents, providing a novel route for pursuing cost-effective CO2 capture with an amine solvent.

Interdisciplinary approaches to modeling extraction efficiency and safety for clean energy under coupled multi-field effects

Coal bed methane, a crucial clean energy source, has attracted extensive research attention. Characterized by intricate and rough fracture systems, coal seam is vital for gas migration, which will be influenced by the in situ stress, coal temperature, adsorption–desorption effect, solid deformation, and gas pressure. This paper introduces an innovative, interdisciplinary fractal model that addresses the limitations of current computational models in accurately representing the complex fractures under the coupled multi-field effects. Four novel fractal micro-parameters are introduced to capture the dynamics of rough networks. And rigorous validation against field extraction data reveals that the proposed micro-parameters outperform existing methods in analytical efficacy. Notably, those micro-parameters significantly influence fracture behavior and gas seepage. For instance, a DT increase from 1.2 to 1.8 and an ε rise from 0.06 to 0.18 lead to a respective 29.8% and 22.7% increase in gas pressure. Moreover, alterations in these fractal micro-parameters under coupled multi-field effects markedly impact coal bed stress, raising safety concerns in engineering projects, with a potential increase in coal stress by up to 2.62%. This research offers innovative insights into the complex coupled mechanisms governing rough fractures and significantly advances the understanding of the efficiency and safety in clean energy extraction processes.

Effects of Adsorption and Desorption of Low-Boiling-Point Total Hydrocarbon Gases on Activated Carbon.

In this study, we selected materials that efficiently adsorb total hydrocarbons (THCs) from petrochemical storage facilities and applied four types of activated carbons to adsorb THCs to evaluate their properties. Four gases with low boiling points, namely, ethylene, ethane, propylene, and propane, generated via petrochemical storage facilities, were selected and mixed to a constant concentration with four types of materials and used to investigate the adsorption capacities and desorption properties. The adsorbents comprised two raw materials and two chemically activated materials. The specific surface areas of activated palm (2085 m2/g) and coal (1752 m2/g), which are chemically activated carbons, exhibited a twofold increase compared to those of raw palm (1232 m2/g) and coal (946 m2/g). Thus, we identified the correlations between the physical properties of the activated carbon adsorption materials and their adsorption capacities for four low-boiling-point THCs generated by petrochemical storage facilities.

Heavy metal transport with adsorption for instantaneous and exponential attenuation of concentration

Heavy metal pollutant is a serious problem in environmental pollution, and it is very difficult to eradicate once it enters the soil. As heavy metal adsorption has been proven to occur, the heavy metal’s behaviour can be modeled as a transport equation with adsorption. Previous adsorption term mostly due to the concentration alone, while in here, the desorption effect given by the rate of change of the concentration is also included. Also, the heavy metals are frequently considered to enter the soil after being dumped into the soil for a certain period of time. But, quick dumping onto the soil can introduce heavy metal instantaneously. Heavy metals entering the soil through leaching or when their concentration in the soil is influenced by chemical reactions, can all lead to the exponential decay of heavy metals entering the soil. Based on two-dimensional advection diffusion equation (ADE) with the new adsorption term, analytical solutions are obtained for the cases of instantaneous and exponential attenuation of heavy metals emission to soil by the method of Laplace transform. The results highlight the significant influence of emission type on the peak concentrations. If heavy metals are instantaneously enter the soil, the peak occurs in the range of 1–3 m radius from the point of emission on the first day, while for exponential attenuation the peak occurs close to the point of emission. Furthermore, there exists a correlation between retardation factors and heavy metal concentrations, where a decrease in retardation factors leads to an increase in heavy metal concentration. It is essential to investigate both types of heavy metals emission to provide valuable information for proper pollution management, effective environmental regulations and enforcement.

QUANTIFYING ROUGH FRACTURE BEHAVIORS IN GAS-BEARING COAL SEAM: A FULLY COUPLED FRACTAL ANALYSIS

In gas-bearing coal seam mining projects, the pivotal considerations encompass the assessment of gas migration, emission trends, and coal seam stability, which are crucial for ensuring both the safety and efficiency of the project. The accurate evaluation of the nonlinear evolution of the fracture network, acting as the primary conduit for gas migration and influenced by mining disturbances, coal seam stress, overlying strata pressure, and gas pressure, emerges as a key determinant in gauging coal seam stress and safety. To address the industry challenge of quantitatively assessing the complex behaviors of fracture networks during gas-bearing coal seam extraction, this study introduces a novel, interdisciplinary fractal analysis model. Drawing upon fractal theory for classical porous media, four fractal parameters capable of quantitatively characterizing the microscopic behaviors of fractures are proposed and defined as functions of permeability. Subsequently, the gas pressure in gas-bearing coal seams, coal seam deformation and stress, in-situ stress, overlying strata pressure, and adsorption–desorption effects are comprehensively coupled and applied to the classic gas-bearing coal seam at the Jianxin Coal Mine’s 4301 working face in Shaanxi, China. Upon the robust validation of the proposed model, the present computational results reveal: (1) the proposed micro-parameters adeptly characterize the number, roughness, tortuosity, and length of fractures in gas-bearing coal seams; (2) a larger fractal dimension of fractures leads to increased coal seam stress and strain, while the fractal dimensions of fracture tortuosity and roughness are inversely proportional to coal seam stress and strain; (3) these fractal parameters directly induce evolutionary changes in gas seepage behavior, leading to varying degrees of mechanical property evolution in the coal seam. When [Formula: see text] and [Formula: see text] increased from 1.2 to 1.8, the maximum change in coal seam deformation was 16.9% and 13.8%, respectively, and when [Formula: see text] increases from 0.03 to 0.12, the coal seam deformation changes by 15.1%. This represents a quantitative characterization unattainable by previously published coal seam analysis models, including mainstream fractal computation models.

The Adsorption and Desorption Effects of Nylon-6-resin with Epothilone B

The Adsorption and Desorption Effects of Nylon-6-resin with Epothilone B

A multi-scale fractal model of gas flow considering the evolution of kerogen microstructure and the multi-physical coupling

Shale is a complex porous medium. The migration mechanism within its different microstructural systems is crucial for the efficient recovery of shale gas. The kerogen microstructure influences the adsorption–desorption effect of the reservoir. This study accounts for the heterogeneity of shale and uses fractal dimension to characterize the fracture and inorganic matrix systems. It also establishes a kerogen fractal diffusion model by integrating fractal diffusion with fractal theory. Furthermore, this study analyzes the effect of evolution of micro structural parameters of kerogen on macro permeability, such as: (1) kerogen fractal dimension; (2) effective diffusion coefficient of kerogen; (3) maximum kerogen aperture. Numerical simulation shows that: The maximum pore size and porosity of kerogen in direct proportion to fractal dimension and effective diffusion coefficient. The fractal dimension and effective diffusion coefficient decrease gradually during shale gas extraction. The fractal effective diffusion has a significant impact on cumulative gas extraction.

Sb segregation in ultrathin GaAsSb layers: A quantitative analysis of soaking/desorption stages

We present a quantitative analysis of Sb segregation in ultrathin GaAsSb films (1–20 ML) grown with soaking/desorption methods. Sb soaking advances Sb incorporation almost to the beginning of the growth, increasing the compositional gradient for all thicknesses. Application of the desorption step alone increases the compositional gradient at the upper interface by removing a fixed amount of Sb but erases layers thinner than 10 ML. When both methods are combined, the Sb balance changes with layer thickness. Thinner layers lose Sb while thicker layers gain Sb. The amount of Sb desorbed is related to the floating layer content at the time of desorption, which varies with thickness. Segregation simulations show that the segregation energy changes during layer growth, being initially higher but stabilizing around the same value for all cases. Sb-soaked samples reach the segregation steady state at a distance of 5 ML from the origin, much earlier than non-soaked samples (10–15 ML). The effect of desorption produces a large perturbation of the segregation steady state, which is much greater in the desorption-only sample than when combined with soaking. The combined effect of soaking and desorption gives the best GaAsSb films with steeper interfaces and no delay in onset.

Sustainable per‐ and polyfluoroalkyl substances contaminated soil remediation: Evaluating the potential of thermal desorption

AbstractPer‐ and polyfluoroalkyl substances (PFASs) have been extensively utilized in various industries. These artificial compounds pose significant environmental and health concerns as they exhibit persistence in soil over long periods and can migrate through soil and groundwater. One potential method for addressing PFASs toxicity is thermal desorption, although its efficacy in calcareous soil remains understudied. In this experimental investigation, we aimed to evaluate the effectiveness of thermal desorption in removing PFASs from two types of calcareous soil: spiked clay and sandy clay loam soil. PFASs were spiked into soil samples, which were subsequently freeze‐dried and homogenized. The samples underwent thermal desorption, followed by extraction and analysis of remaining PFASs concentrations using UPLC MS/MS. The study examined the impact of different temperatures, times, and soil types on PFASs removal. Results revealed that the removal fraction of PFASs increased with higher temperatures, although the specific effect varied depending on the soil type and the characteristics of the PFASs. Optimal PFASs removal occurred within the temperature range of 350 to 450°C, with a treatment time of 40 to 60 min. ANOVA analysis indicated a significant interaction between temperature and time, highlighting the influence of temperature on PFASs desorption. The correlation coefficient demonstrated a negative relationship between temperature and PFASs removal from the soil sample. This study successfully demonstrated the effectiveness of thermal desorption in removing PFASs from calcareous soils. The findings contribute to the development of effective strategies for mitigating the environmental and health risks associated with PFASs contamination in soil.

Ppb-level NH3 photoacoustic sensor combining a hammer-shaped tuning fork and a 9.55 µm quantum cascade laser

We present a quartz enhanced photoacoustic spectroscopy (QEPAS) gas sensor designed for precise monitoring of ammonia (NH3) at ppb-level concentrations. The sensor is based on a novel custom quartz tuning fork (QTF) with a mid-infrared quantum cascade laser emitting at 9.55 µm. The custom QTF with a hammer-shaped prong geometry which is also modified by surface grooves is designed as the acoustic transducer, providing a low resonance frequency of 9.5 kHz and a high-quality factor of 10263 at atmospheric pressure. In addition, a temperature of 50 °C and a large gas flow rate of 260 standard cubic centimeters per minute (sccm) are applied to mitigate the adsorption and desorption effect arising from the polarized molecular of NH3. With 80-mW optical power and 300-ms lock-in integration time, the detection limit is achieved to be 2.2 ppb which is the best value reported in the literature so far for NH3 QEPAS sensors, corresponding to a normalized noise equivalent absorption coefficient of 1.4 × 10−8 W cm−1 Hz−1/2. A five-day continuous monitoring for atmospheric NH3 is performed, verifying the stability and robustness of the presented QEPAS-based NH3 sensor.

Moisture Absorption, Desorption and Reabsorption Effects on Mechanical Properties of Glass-Epoxy Composites

The glass-epoxy composite laminates were fabricated using BID glass fabric and RT cure epoxy matrix by Room Temperature Vacuum Bag Moulding (RTVBM) Technique. The Inter laminar shear strength (ILSS), compression and flexural strength values were determined at room temperature for their dry mechanical property evaluation. The test specimens were exposed to a temperature/humidity condition at 45° C/95% RH for moisture absorption studies. The moisture desorption studies were carried out in a temperature oven at 45° C and 85° C. The mechanical properties of the exposed specimens were evaluated during absorption and desorption conditions. Scanning Electron Microscopy (SEM) studies were carried out on the dry and exposed specimens to determine the effect of moisture on the fracture behaviour of glass-epoxy composites. Results show that, moisture reabsorption and full desorption are faster than the absorption and partial desorption. This may be due to, change of material properties after a cycle of moisture absorption and desorption phenomenon. The mechanical strength (ILSS, compression and flexural) has been found to reduce continuously with increased duration of environmental exposure, but a slight shift back of the strength has been observed for desorbed samples.

The Effect of Conductive Polyaniline on the Anti-Fouling and Electromagnetic Properties of Polydimethylsiloxane Coatings.

In this paper, four conductive polyaniline powders doped in hydrochloric acid, sulfuric acid, phosphoric acid, and sulfonic acid were selected and blended with polydimethylsiloxane to prepare coatings with an electromagnetic absorption effect and fouling desorption effect, respectively. A UV spectrophotometer was used to evaluate the settling rate of the powders. Fourier transform infrared spectrometry, laser confocal microscopy, and scanning electron microscopy were used to observe the morphology and structure of the powder and the coating. The interface properties of the coatings were characterized using a contact angle measurement, the mechanical properties of the coatings using a tensile test, and the electromagnetic properties of the powders and microwave absorption properties of the coatings using vector network analyzers. Meanwhile, the antifouling performance of the coatings was evaluated via the marine bacteria adhesion test and benthic diatom adhesion test, and the effect of conductive polyaniline on the antifouling performance of the coating was analyzed. The results show that adding polyaniline reduced the surface energy of the coating and increased the roughness, mechanical properties and anti-fouling properties of the coating. Moreover, adding appropriate polyaniline powder can enhance the electromagnetic wave loss of the coating. The followings values were recorded for a hydrochloric-acid-doped polyaniline coating: lowest surface energy of 17.17 mJ/m2, maximum fracture strength of 0.95 MPa, maximum elongation of 155%, maximum bandwidth of 3.81 GHz, and peak of reflection loss of -23.15 dB. The bacterial detachment rate of the polydimethylsiloxane (PDMS) samples was only 30.37%. The bacterial adhesion rates of the composite coating containing hydrochloric-acid-doped polyaniline were 4.95% and 2.72% after rinsing and washing, respectively, and the desorption rate was 45.35%. The chlorophyll concentration values were 0.0057 mg/L and 0.0028 mg/L, respectively, and the desorption rate was 54.62%.

Electron beam remediation of soils impacted with heavy hydrocarbons

During electron beam (EBeam) irradiation, high-energy electrons can generate physical and chemical changes in a substance such as chain scission and cross-linking. Irradiation of soil is shown to be an effective technology for rapid reduction of Total Petroleum Hydrocarbons (TPH) in crude oil impacted soils. An experimental apparatus for batch treatment of 100 g soil samples was built and tested using a 10 MeV, 15 kW electron beam. The samples were a variety of crude oil impacted soil samples with TPH contents ranging between 1.6 and 32% by mass. Soils of initial TPH up to 9.1% (dry weight basis) TPH levels were reduced to below a target cleanup level of 1% with irradiation doses ranging from 700 kJ/kg to 1100 kJ/kg and treatment times less than 200 s, with maximum soil temperatures less than 450 °C. Soils with elevated moisture content required higher dosages or preliminary drying. EBeam treatments resulted in 1) reduction for both light and heavy hydrocarbon, 2) generation of new light hydrocarbons, and 3) generation of fixed carbon, indicating that the mechanisms of electron beam remediation include radical induced reactions at relatively low temperature and relatively short time scales and not simply thermal desorption effects.

Self-Excited-Resonance of Soil-Engaging Surface Spectrum: A New Method of Soil Cutting Resistance Reduction

In this study we explored the methods and effects of spectral resistance reduction for soil-engaging surface of self-excited resonant bulldozing plates with a plane base on the basis of resonance effects. In the acquisition of the low-order vibration frequency f0 of the bin soil, centering around frequency point f0, eight spatial geometric wave frequency points ni of soil-engaging surfaces and three amplitudes were selected; by superimposing with soil-engaging surfaces of plane-based bulldozing plates, 24 spectral structures of the soil-engaging surface of bulldozing plates and model samples were combinatorically designed. Resistance reduction characteristics of each model sample were tested using an indoor soil bin test. Near the resonance point f0, the structures of the self-excited vibrating frequency spectrum of the soil-engaging surface obtain a preferable inhibitory effect on working resistance. At a 4 mm amplitude resonance point, model samples achieved the best resistance reduction effect, with a maximum relative resistance reduction rate of 22.67%, and the soil desorption effect of the relevant model sample was also good. On the other hand, away from the resonance point, whether the frequency increased or decreased, the corresponding working resistance of the model sample surfaces increased relatively. This is in good agreement with the law that the resonance point amplitude of the theoretical resonance curve is higher and the amplitude on both sides is lower. This paper provides a reference for the parameter design and related product development for various forced or self-excited vibration soil cutting tools.

Decoupling the Conflicting Roles of Photoactivation and Boosting Chemiresistor Response by Pulsed UV Light Modulation.

UV photoactivation has been widely employed to trigger the response of semiconductor chemiresistors at room temperature (RT). Generally, continuous UV (CU) irradiation is applied, and an apparent maximal response could be obtained via optimizing UV intensity. However, owing to the conflicting roles of (UV) photoactivation in the gas response process, we do not think the potential of photoactivation has been fully explored. Herein, a pulsed UV light modulation (PULM) photoactivation protocol has been proposed. Pulsed UV-on facilitates the generation of surface reactive oxygen species and refreshes the surface of chemiresistors, while pulsed UV-off avoids the side effects of UV-induced desorption of the target gas and the decline of base resistance. PULM enables decoupling those conflicting roles of CU photoactivation, resulting in a drastic boost of response to trace (20 ppb) NO2 from 1.9 (CU) to 131.1 (PULM UV-off), and a decline of limit of detection from 2.6 ppb (CU) to 0.8 ppb (PULM) for a ZnO chemiresistor. This work highlights that PULM allows full exploitation of the potential of nanomaterials for sensitively detecting trace (ppb-level) toxic gas molecules and opens a new opportunity for designing highly sensitive, low-power consumed RT chemiresistors for ambient air quality monitoring.

Preparation of porous calcium carbonate biochar and its beryllium adsorption performance

Wastewater disposal from beryllium production has become a significant problem in the industry. Therefore, this paper designed porous calcium carbonate biochar (CC-LBC) using Na2CO3 and CaCl2 to modify the biochar innovatively, after which we understudied the Be(II) adsorption effect of CC-LBC at different concentrations. The results from Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and other characterization analyses showed that when CC-LBC particles were immersed in the Be(II) waste liquid, several O elements accumulated because of its loose and porous structure, generating more beryllium precipitates on the surface of the adsorbent. According to kinetic data fitting, investigations also revealed that both physical and chemical reactions controlled CC-LBC/Be(II) adsorption process, indicating that the CC-LBC/Be(II) adsorption system is suitable for the intraparticle diffusion model. Furthermore, when the beryllium on activated carbon was desorbed by 10% NaOH, the desorption effect was above 80%, and the saturation adsorption capacity of CC-LBC for Be(II) was up to 55 mg/g. However, when the initial concentration of Be(II) was equal to 0.5–1 mg/L, the concentration of beryllium after treatment was lower than 10 μg/L, confirming that CC-LBC had a better selective adsorption performance for beryllium in the binary system.

Dual effects of ultrasound on fabrication of anodic aluminum oxide

Ultrasound has been proven to enhance the mass transfer process and impact the fabrication of anodic aluminum oxide (AAO). However, the different effects of ultrasound propagating in different media make the specific target and process of ultrasound in AAO remain unclear, and the effects of ultrasound on AAO reported in previous studies are contradictory. These uncertainties have greatly limited the application of ultrasonic-assisted anodization (UAA) in practice. In this study, the bubble desorption and mass transfer enhancement effects were decoupled based on an anodizing system with focused ultrasound, such that the dual effects of ultrasound on different targets were distinguished. The results showed that ultrasound has the dual effects on AAO fabrication. Specifically, ultrasound focused on the anode has a nanopore-expansion effect on AAO, leading to a 12.24 % improvement in fabrication efficiency. This was attributed to the promotion of interfacial ion migration through ultrasonic-induced high-frequency vibrational bubble desorption. However, AAO nanopores were observed to shrink when ultrasound was focused on the electrolyte, accompanied by a 25.85 % reduction in fabrication efficiency. The effects of ultrasound on mass transfer through jet cavitation appeared to be the reason for this phenomenon. This study resolved the paradoxical phenomena of UAA in previous studies and is expected to guide AAO application in electrochemistry and surface treatments.

Numerical study on coupled modelling of artificial freezing marine soil

A theoretical model is proposed to investigate the coupling of the hydro-ice-salt-crystalline-thermal-mechanical of the artificial frozen marine soil in coastal areas. The influence of non-convective and thermal permeability in the fields of salt, pressure, thermal, and water, the compressibility of solid particles, as well as solute potential and ice resistance coefficients in convective flux are comprehensively considered based on the mass, energy, and momentum conservation equations. The proposed coupling model is solved using the COMSOL Multiphysics software. The accuracy of the proposed theoretical model is verified by the model test results in the literature. The parametric studies are conducted to investigate the effects of the key parameters on the freezing process. It is found that the salt desorption of the frozen marine soil cannot be ignored. The effect of salt desorption in the frozen area is strong which makes the adsorbed salt content in the unfrozen area greater than that in the frozen area. The change in salt mass fraction has a great influence on the overall frost heave, salt heave and water freezing. With the increase of overburden, the soil is compressed and the desorption effect is enhanced in the frozen area.

Study on Multiscale Fluid–Solid Coupling Theoretical Model and Productivity Analysis of Horizontal Well in Shale Gas Reservoirs

In order to study the productivity dynamic evolution laws of shale gas horizontal well, a multiscale seepage theoretical model considering the fluid–solid coupling effect is proposed first in this paper, which introduces an anisotropic matrix permeability model that comprehensively considers multiple flow regimes and an artificial hydraulic fracture conductivity model that considers proppant deformation and embedment. Then the reliability of the theoretical model is verified by the field production data obtained from the Marcellus shale. Based on the established productivity model, the evolution laws of pore pressure and permeability in different areas of the reservoir with different production periods are studied first, and then the shale gas production rate and cumulative production under different physical mechanisms, different shale gas flow regimes, and different reservoir parameters are quantified and analyzed. The simulation results show that the pore pressure in the hydraulic fracture area decreases rapidly at the initial stage of production, resulting in large deformation, and the fracture conductivity tends to be stable gradually at the later stage of production. The desorption effect will increase shale gas production, while the stress sensitivity is just the opposite. When only real gas flow is considered, the gas cumulative production is the highest. The fluid–solid coupling of hydraulic fractures has a great impact on the production, while the fluid–solid coupling in the matrix area has a small impact on the production, which can be ignored if appropriate. During the sensitivity analysis of reservoir parameters, it is observed that the influence of parameters of hydraulic fractures on production is much higher than that of matrix regional parameters. During the production process, these influencing factors can be adjusted according to the change of production data to achieve the optimization of shale gas production. In a word, the new model proposed in this paper provides a more accurate method to estimate the impact of multiple physical mechanisms, especially the fluid–solid coupling effect, on shale gas production compared with the existing model. The research results of this study can provide some reference and guidance for the dynamic prediction of shale gas production and optimization of production parameters.

Study on gas desorption-diffusion behavior from coal particles using triple-pore structure models: Experimental, mathematical models, and numerical solutions

To accurately describe gas emissions from coal particles, a conceptual model comprising macropores, mesopores, and micropores has been proposed. On the basis of the conceptual model, two mathematical models were developed for gas diffusion from coal particles: Model Ⅰ includes the effect of desorption, while Model Ⅱ does not. The models were then validated by comparing them to experimental data obtained from gas desorption diffusion kinetic tests. Meanwhile, the effective diffusion coefficients for pores of varying scales were gained and analyzed. The results indicated that both models were capable of providing a reasonable fit to the experimental data; however, Model Ⅱ was unable to provide a good fit to the experimental data from the initial stage, which Model Ⅰ captured well. This indicates that gas desorption could accelerate gas emission from coal particles in their initial state; the increase of the porosity of micropore or macropore has a significant effect on total gas emission and a moderate effect on the initial gas emission volume, whereas the variation of the porosity of mesosphere could have a remarkable influence. This demonstrated that the intensity of gas desorption in coal with abundant mesopores is greater than that of coal with fewer mesopores in the initial desorption phase. In Model Ⅰ, the effective coefficients for pores of different scales varied significantly with increasing pressure, whereas in Model Ⅱ, this was not the case, with the exception of the effective diffusivity of macropores. The results of the current study have significant implications for the determination of gas contents for gas resources calculations, gas flow in the coal matrix, and the prediction of coal seams outburst.