Concentration Of Free Radicals Research Articles

EPR Study of Coffee

Six medium and dark roast coffees and its grounds and one non-roast coffee samples in solidstate from the one of coffee shops in Ulaanbaatar city were studied by the EPR spectroscopy.Singlet, low intensity but broad (16-17 Gs) EPR spectrum was registered near the 3400 Gsmagnetic field from the all samples. Free radical concentration was evaluated about 1016 spinwhich can be a measure of antioxidative property.

Simultaneous Pyrolysis of Coal and Biomass in a Drop-Tube-Fixed-Bed Reactor.

Copyrolysis of coal and biomass has been extensively studied to exploit its inherent synergistic effects; however, the different pyrolysis temperature zones of coal and biomass seriously affect the realization of these effects. Therefore, a new copyrolysis method (preheating the coal to a certain temperature and then adding the biomass in a drop-tube–fixed-bed reactor, denoted as M1) was designed herein to achieve “simultaneous” pyrolysis of coal and biomass. The yields of products and the characteristics of M1-produced tar were estimated and compared with those of tar obtained by fixed-bed-reactor (denoted as M2)-based copyrolysis. M1 achieved a higher tar yield and lower water content than M2. The M1-generated tar exhibited a lower free-radical concentration, higher H/C ratio, higher levels of uncondensed aromatic hydrogen, and shorter side-chains than that produced by M2. The temperature of HLBE coal at which the WSs were fed to the reactor in M1, denoted as TF, affects the “simultaneous” pyrolysis. TF values of 300, 400, and 500 °C were studied, and it was found that the tar yield obtained at a TF of 400 °C (the main pyrolysis temperature of coal) is the highest, the water yield is the lowest, and the free-radical concentration of the tar is also the lowest among the investigated samples.

Physical and Chemical Mechanisms of Reactions that Proceed at Extremely High Rates in a Propagating Flame and the Detonation of Gas

The characteristic periods of the reactions in a propagating flame and the detonation of most gases are found to be less than 10−4 and 10−6 s, respectively. The extreme rates and accelerations of reactions responsible for such short times correspond to the law of the dependence of the rate of the combustion reaction on temperature, which is an exponent containing a Boltzmann factor in a positive power index. The kinetics of the processes is determined mainly by a sharp increase in the concentrations of free atoms and radicals as they approach those of the initial reagents. The conclusions of the theory agree with experimental results.

Forced Solid-State Oxidation Studies of Nifedipine-PVP Amorphous Solid Dispersion.

In the present study, the oxidative degradation behavior of nifedipine (NIF) in amorphous solid dispersions (ASDs) prepared with poly(vinyl pyrrolidone) (PVP) with a short (K30) and a long (K90) chain length was investigated. The ASDs were prepared via dry ball-milling and analyzed using Fourier transform infrared (IR) spectroscopy, X-ray scattering, and differential scanning calorimetry. The ASDs were exposed to accelerated thermal-oxidative conditions using a pressurized oxygen headspace (120 °C for 1 day) and high temperatures at atmospheric pressure (60-120 °C for a period of 42 days). Additionally, solution-state oxidative degradation studies showed that pure NIF degrades to a greater extent than in the presence of PVP. Electronic structure calculations were performed to understand the impact of drug-polymer intermolecular interactions on the autoxidation of drugs. While no drug degradation was observed in freshly prepared ASD samples, alkyl free radicals were detected via electron paramagnetic resonance (EPR) spectroscopy. The free radicals were found to be consumed to a greater extent by PVP K30- than PVP K90-based ASDs upon exposure to high oxygen pressures. This was consistent with the greater solid-state oxidative degradation of NIF observed in ASDs with PVP K30 than with PVP K90. As no drug recrystallization occurred during this study period, the lower glass-transition temperature and presumed greater molecular mobility of PVP K30 and its ASD as compared to the PVP K90 system appear to contribute to the greater drug degradation in PVP-K30-based ASDs. The extent and the rate of oxidative degradation were higher in the case of PVP-K30-based ASD as compared to that in PVP-K90-based ASD, and the overall degradation increased with an increase in temperature. IR spectral analysis of drug-polymer interactions supports the electronic calculations of the oxidation process. We infer that, apart from the initial free radical content, the difference in the extent of drug-polymer intermolecular interactions in ASDs and amorphous stabilization during the forced oxidation experiments contribute to the observed differences in the autoxidative reactivity of the drug in ASDs with different PVP chain lengths. Overall, the chemical degradation of NIF in ASDs with two PVP chain lengths obtained from accelerated solid-state oxidation studies was in qualitative agreement with that obtained from long-term (3 years) storage under ambient conditions. The study highlights the ability of accelerated processes to determine the oxidative degradation behavior of polymeric ASDs and suggests that the polymer chain length could factor into chemical as well as physical stability considerations.

Effect of operating conditions and water matrix on the performance of UV combined electrochemical process for treating Chloride-containing solution and its reaction mechanism

The performance of ultraviolet combined electrochemical (EC) process for treating chloride-containing (UV/EC/Cl-) solution was evaluated based on the N, N-Diethyl-m-toluamide (DEET) degradation. The influences of operating conditions and water matrix on the DEET degradation were investigated, and the reaction mechanism of UV/EC/Cl- process was discussed based on the analysis of DEET degradation pathway, the detection of the steady-state concentrations of active free radicals and the analysis of free radicals scavenging. The observed reaction rate constant of DEET degradation in UV/EC/Cl- process (0.093 min−1) is significantly higher than that of UV/Cl2 process (0.036 min−1), and the synergistic effect on the DEET degradation is remarkable in UV/EC/Cl- process. The current and chloride concentration have remarkable impact on the DEET degradation, while the initial pH, reaction temperature, and initial DEET concentration have slight influence on the DEET degradation. The impact of alkalinity on DEET degradation is more significant than that of ammonia, while sulfate and phosphate have slight effect on the DEET degradation. The active points attacked by free radicals on DEET molecule were predicted basing on density functional theory. During the DEET degradation, small molecular products are produced through a series of reactions such as hydrogen abstraction, substitution, dealkylation, and ring-opening. The steady-state concentrations of HO• and Cl• in UV/EC/Cl- process (1.57 × 10-13 M and 2.37 × 10-14 M, respectively) are higher than those of UV/Cl2 process (1.23 × 10-13 M and 1.07 × 10-14 M, respectively), and HO• and Cl• play key roles in the DEET degradation during the UV/EC/Cl- process.

Non-Stacked γ-Fe2O3/C@TiO2 Double-Layer Hollow Nanoparticles for Enhanced Photocatalytic Applications under Visible Light.

Herein, a non-stacked γ-Fe2O3/C@TiO2 double-layer hollow nano photocatalyst has been developed with ultrathin nanosheets-assembled double shells for photodegradation phenol. High catalytic performance was found that the phenol could be completely degraded in 135 min under visible light, due to the moderate band edge position (VB at 0.59 eV and CB at −0.66 eV) of the non-stacked γ-Fe2O3/C@TiO2, which can expand the excitation wavelength range into the visible light region and produce a high concentration of free radicals (such as ·OH, ·O2−, holes). Furthermore, the interior of the hollow composite γ-Fe2O3 is responsible for charge generation, and the carbon matrix facilitates charge transfer to the external TiO2 shell. This overlap improved the selection/utilization efficiency, while the unique non-stacked double-layered structure inhibited initial charge recombination over the photocatalysts. This work provides new approaches for photocatalytic applications with γ-Fe2O3/C-based materials.

Design and Synthesis of Some 1,3,4-Thiadiazole Amines: Molecular Docking, in silico ADMET, in vitro Antimicrobials and Antioxidant Studies

An increase in free radical concentration in the human body due to medications leads to oxidative stress can be counteracted by novel antioxidative agents that lower the concentration of free radical and free radical damages in human body. In present study, 2-thiophene 4-thiadiazole quinoline derivatives (5a-e) were designed and synthesized using 2-thiophene quinoline 4-carboxylic acids and thiosemicarbazide. The designed compounds 5a-e were docked against the protein PDB-ID: 1OC3 and evaluated the antioxidant activity using DPPH assay and also screened for antibacterial and antifungal potential by Agar well diffusion assay followed by in vitro antitubercular assay by MABA method. The IC50 values for compounds 5a and 5b were 415 μg/mL and 396 μg/mL. The binding affinity of docked ligands against the protein 1OC3 ranges from -6.2 to -5.7 kcal/mol. In an antimicrobial investigation, the compounds were found to be active against both bacteria and fungi, as well as sensitive to M. tuberculosis.

Hepatoprotective effect of ferulic acid and/or low doses of γ-irradiation against cisplatin-induced liver injury in rats.

The therapeutic efficacy of cisplatin (CIS) is limited owing to its hepatotoxic side effects. The current study aimed to investigate the protective impact of ferulic acid (FA) and low-doses of γ-irradiation (LDR) against CIS-prompted hepatotoxicity in rats. Adult male Swiss albino rats were divided into eight groups: untreated group; FA, LDR, and CIS treated groups; and combinations of one or more of the above treatments. Post-treatment analyses included measuring redox markers like SOD and CAT activity, NO free radical content, and lipid peroxidation in liver tissue. Serum aminotransferase activities were also determined. Additionally, gene transcript levels of liver NF-ҡB-P65, caspase-1, COX-2, and IL-1β were quantified. Moreover, immunohistochemistry for caspase-3 and histopathological examinations were estimated in liver tissue. Our findings revealed increased levels of oxidative stress along with a significant reduction in anti-oxidative responses and a significant increase in serum aminotransferase activities in the CIS-intoxicated group. A similar increase was also observed in COX-2 and IL-1β transcript levels and caspase-3 enzyme activity, besides a decrease in transcript levels of NF-ҡB-p65 and caspase-1, indicating an overall inflammatory trend and an increase in the apoptotic shift. The co-administration of FA and/or treatment with LDR has ameliorated the hepatotoxic effect induced by CIS. The histopathological investigation of liver tissues confirmed this ameliorating action of these adjuvant therapies against CIS toxicity. In conclusion, it is plausible to suggest that the hepatoprotective effects of co-administration of FA and/or LDR against CIS-induced hepatotoxicity are attributed to the possession of anti-oxidative, anti-inflammatory, and anti-apoptotic capabilities.

Narrative Review of Russian, Ukrainian and English-Language Publications Investigating the Effects of Photobiomodulation on Red Blood Cell Physiology.

Objective: The beneficial effects of photobiomodulation (PBM) on cellular function are well characterized, principally deriving from the absorption of red to near-infrared radiation by chromophores such as cytochrome-c-oxidase. However, the effects and underlying mechanisms of PBM on non-mitochondria containing cells, such as red blood cells (RBCs), are relatively unknown. In this review, we evaluate studies that investigated the effects of PBM on RBCs in the peripheral circulation, with particular attention on changes in the structural and functional features of RBC membrane dynamics, as well as the potential implications of PBM as an intervention for pathologies related to RBC dysfunction. Methods: A literature review was performed in concordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol, using the following databases: PubMed; Ovid (OvidMedline); Scopus; Web of Science; Google Scholar; Scholar.ru; eLIBRARY.ru; Digital Library: Dissertation; and Russian State Library. Search results included publications in Russian, Ukrainian, and English languages after 1995. Eligible articles included the effects of PBM on RBC membrane morphology and function in the peripheral circulation, used either in isolation or alongside other interventions. Results: The majority of articles indicated beneficial changes in RBC structure and function following exposure to PBM, including increased osmotic resistance, normalization of membrane permeability, decreased free radical oxidation and concentration of intermediate products of lipid peroxidation, reduced phospholipase A2 membrane activity, and normalization of the viscoelastic properties of RBCs and erythrocyte deformability index. Most trials had small patient numbers with no long-term follow-up. Conclusions: The importance of RBC membrane dysfunction as a potential marker and mechanism for RBC pathologies was highlighted. PBM has shown to have membrane protective effects. Further clinical trials are recommended to provide more evidence PBM therapy to treat RBC-related diseases, which may, at the correct dose, improve RBC stability and deformability in RBC-related pathologies.

Effects of mixing ozone on combustion characteristics of premixed methane/oxygen in meso-scale channels

To investigate the effect of ozone on the combustion characteristics of premixed methane/oxygen in meso-scale channels, the flammability limits of the mixture with ozone are obtained experimentally, and the influence of ozone concentration on the near-limit combustion process is analyzed from the perspective of thermal effect and chemical kinetics effect by numerical simulation. Moreover, the changes of OH radicals, outer wall temperature and wall heat loss in mixture mixing ozone are compared. The results show that mixing ozone can significantly broaden the flammability limit of premixed methane/oxygen, increase the reaction temperature, and make the combustion zone move towards the inlet. Also, the chemical effect of ozone is more significant than its thermal effect. The concentration of OH and other free radicals are increased significantly by the interaction between the O atom produced by ozone decomposition and fuel molecules, which further accelerates the chain branching reaction, and enhances the whole combustion process. However, the total heat loss is increased by 4%–8% due to the sharp raising of radiation heat. Additionally, it is found that under non-stoichiometric conditions and low inlet flow rate, the increase of OH radical and outer wall temperature is more obvious, and the wall heat loss is also larger.

Synthesis of Silymarin-Gold Nanoparticle Conjugate and Analysis of its Liver-Protecting Activity.

The liver disease problem prompts investigators to search for new methods of liver treatment. Silymarin (Sil) protects the liver by reducing the concentration of free radicals and the extent of damage to the cell membranes. A particularly interesting method to increase the bioavailability of Sil is to use synthesized gold nanoparticles (AuNPs) as reagents. The study considered whether it was possible to use the silymarin-AuNP conjugate as a potential liver-protecting drug. AuNPs were conjugated to Sil and the liver-protecting activity of the conjugate was examined. Experimental hepatitis and hepatocyte cytolysis after carbon tetrachloride action were used as a model system, and the experiments were conducted with laboratory animals. For the first time, silymarin was conjugated to colloidal gold nanoparticles (AuNPs). Electron microscopy showed that the resultant preparations were monodisperse and that the mean conjugate diameter was 18-30 nm ± 0.5 nm (mean diameter of the native nanoparticles, 15 ± 0.5 nm). In experimental hepatitis in mice, conjugate administration interfered with glutathione depletion in hepatocytes in response to carbon tetrachloride. It also was conducive to an increase in energy metabolism and stimulated the monocyte-macrophage function of the liver. The results were confirmed by the high respiratory activity of the hepatocytes in cell culture. We conclude that the silymarin-AuNP conjugate holds promise as a liver-protecting agent in acute liver disease caused by carbon tetrachloride poisoning.

Influence of Temperature Change on the Change Law of Free Radicals in Coal.

This study investigates changes in the concentration and types of free radicals in the process of coal heating, first rising and then falling. Hailar lignite, Panjiang bituminous coal, and Yangquan anthracite were selected as coal test samples. The results show that the lignite’s concentration of free radical changes during heating is greater than that of bituminous coal or anthracite. It clearly shows that lignite is more prone to spontaneous combustion. In the heating and cooling portion of the experiment, the concentration of free radicals during the cooling process was much more than that of free radicals at the same temperature during the heating process. These results obtained from this research study can provide a reference for the prevention and control of the spontaneous combustion of coal with changes in temperature. This study provides a theoretical basis for the prevention and control of spontaneous combustion of coal and the selection of retarding agents and methods in the process of flame retarding by testing the free radical changes of coal at different temperatures. Also, it provides a reference for preventing and controlling coal oxidation with the change in temperature, first rising and then falling.

Assessing the bioavailability and biotoxicity of spiromesifen and its main metabolite spiromesifen-enol (M01) reveals the defense mechanisms of earthworms (Eisenia fetida)

As a promising acaricide and potentially hazardous material, the defense mechanisms of non-target organisms to its exposure are unknown. This study investigates the bioavailability and biotoxicity of spiromesifen and spiromesifen-enol (M01), its main metabolite, in Eisenia fetida. The results showed that M01 was more persistent in the soil environment and E. fetida than spiromesifen. Transcriptome analysis indicated that the spiromesifen- and M01-induced differentially expressed genes (DEGs) were mainly enriched in lysosomal and phagosomal pathways. Analysis of the key common DEGs showed that both spiromesifen and M01 significantly influenced the lysosomes, phagosomes, antioxidant systems, and detoxification systems. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that spiromesifen and M01 damaged E. fetida epidermis and enhanced lysosomal and phagosomal activities. Significant oxidative stress effects were observed at the end of exposure. The hydroxyl free radical (·OH−) content and neutral red retention time (NRRT) could serve as sensitive early biomarkers to predict their pollution. These results revealed the synergistic effects of the epidermis, lysosomes, phagosomes, antioxidant systems, and detoxification system in resisting spiromesifen- and M01-induced damage, which could contribute to the defense mechanisms of non-target organisms against these pollutants.

Impact of co-feeding cracked light products on visbreaking of vacuum residue deasphalted oil

The impact of co-feeding light cracked products on thermal conversion was investigated due to reports that indicated suppression of coking and other benefits during such operation. Specific attention was paid to n-pentane insoluble asphaltenes content and formation. In this study all reactions were performed at 400 °C and 2 MPa initial nitrogen pressure, using a vacuum residue deasphalted oil obtained from Canadian oilsands bitumen. The impact of co-feeding distilled cracked naphtha and kerosene at 5 to 15 wt% was studied. Control reactions included self-reactions of all materials and reactions where the vacuum residue deasphalted oil was replaced by naphthalene. The presence of the distilled cracked naphtha and kerosene did not cause an observable change in the progression of the thermal reaction and no conclusive evidence was found that the development of n-pentane insoluble material in the products was reduced. The reactions products showed no relationship between n-pentane insoluble content, vacuum residue conversion and free radical content. In control experiments the conversion of distilled cracked naphtha and kerosene in naphthalene caused the formation on n-pentane insoluble material, which was not observed during self-reaction of these materials. The results suggested that some of the naphthalene was directly thermally alkylated at 400 °C and that at least some of the resulting products became n-pentane insoluble.

Lignin and organic free radicals in maize (Zea mays L.) seeds in response to aflatoxin B1 contamination: an optical and EPR spectroscopic study.

Aflatoxin B1 (AFB1 ) is the most dangerous of the mycotoxins that contaminate cereal seeds naturally. A stress lignin formation is linked with the accumulation of reactive oxygen species causing a change in the redox status and formation of stable organic radicals, constituting the first layer of defense. The relationship between AFB1 and changes in lignin organic free radicals in seeds is not known, nor is the part of the seed that is more targeted. Using optical and electron paramagnetic resonance spectroscopy, we investigated AFB1 -induced changes in lignin and organic free radicals in seeds, and whether the inner and outer seed fractions differ in response to increasing AFB1 . Different changes in the content of lignin and free radicals with increasing AFB1 concentrations were observed in the two seed fractions. There was a significant positive linear correlation (R=0.9923, P=0.00005) between lignin content and AFB1 concentration in the outer fraction, and no correlation between the lignin content and the AFB1 concentration in the inner fraction. We found a positive correlation between the area of the green spectral emission component (C4) and the AFB1 concentration in the outer fraction. To the best of our knowledge, the results showed, for the first time, that maize seed fractions respond differently to aflatoxin with regard to their lignin and organic free radical content. Lignin content and (C4) area may be reliable indicators for the screening of lignin changes against AFB1 content in the seeds, and thus for seed protection capacity. © 2021 Society of Chemical Industry.

Interactions between Coal and Solvent during the Solvent Extraction of Coal in View of Free Radicals.

In this study, variations in the free radical concentration, degree of swelling (Q), and extraction yield of Buertai coal (C%, 80.4%) in 11 solvents with different characteristics were determined to investigate the interaction between the coal and solvent, as well as the bond cleavage during solvent extraction. Derivative thermogravimetry (DTG) results for the residues and raw coal were compared to confirm whether the covalent bond breaks during solvent extraction. The free radical concentration decreases in certain solvents but increases in a few others. The relative free radical concentration, Q, and extraction yield are positively correlated. The charge-transfer capability of the solvent, and in particular its electron-donating capability, plays an essential role in influencing the interaction between the coal and solvent. The increase in the free radical concentration during solvent extraction can be attributed to (1) the formation or decomposition of charge-transfer complexes, (2) dissociation of charge-transfer complexes into radical ions, and (3) breakage of weak covalent bonds. DTG results show the occurrence of weak covalent bonds breakage at temperatures of 133.9–320.1 °C during solvent extraction due to the reduction of the bond energy caused by the formation of radical ions.

Changes in the composition of a cold-pressed hemp seed oil during three months of storage

Several analytical parameters were evaluated to investigate changes in the composition of a cold-pressed hemp seed oil over a period of 3 months of storage. The environmental conditions applied for the conservation were 12 h of light and 12 of darkness at room temperature, to mime a grocery or supermarket shelf, and the oil was stored in amber glass bottles. The peroxide value was quite low on freshly produced oil (2.66 ± 0.29 mEqO2/kg of oil) and decreased after 3 months (1.35 ± 0.08 mEqO2/kg of oil), as confirmed by free radical concentration, while no other statistically significant (one-way ANOVA, Tukey’s HSD test, p < 0.05) differences were observed (e.g. conjugated diene and triene systems, Oxidative Stability Index and free acidity). The fatty acid, cannabinoids and tocopherols composition did not statistically change; expect for δ-tocopherol, for which a decrease was observed. The overall results did not show a strong effect of photooxidation on the oil, despite its high degree of unsaturation.

Impact of adhesive primer and light-curing on polymerization kinetics of self-adhesive resin cement in association with free radical reaction.

This study analyzed the impact of adhesive primer and light-curing on the polymerization kinetics of urethane dimethacrylate-based self-adhesive resin cement combined with free radical reaction. Specimens were prepared by mixing the cement paste with or without adhesive primer. Subsequently, specimens were light-cured or set without light-curing. The degree of conversion (DC), Vickers hardness (Hv), and free radical concentrations were repeatedly measured up to 168h after the curing initiation. Irrespective of the curing procedures, DC, Hv, and free radical concentration rapidly increased during the initial 30min of curing. The specimens cured with adhesive primer and/or light-curing generally showed higher values of DC, Hv, and radical concentration than those set by chemical curing alone, especially during the initial polymerization phase. Kinetic analysis using a linear mixed model revealed that the adhesive primer had a higher coefficient estimate than light-curing, indicating that the former had a higher impact on the polymerization. Additionally, the adhesive primer alleviated the Hv reduction caused by water and air during the initial polymerization phase, although light-curing hardly prevented the polymerization inhibition. Therefore, we suggest that application of adhesive primer is beneficial to achieve higher degree of conversion and better mechanical properties of self-adhesive resin cements by enhancing free radical reactions.

Continuous 3D printing by controlling the curing degree of hybrid UV curing resin polymer

To achieve high speed and high efficiency continuous 3D printing, interface adhesion between the cured resin and the bottom of the resin tank has to be overcome and fast stripping has to be achieved. In this paper, a method that combines low surface energy Fluorine membrane and low curing degree hybrid resin is proposed to achieve continuous 3D printing. First, the mechanism of continuous printing was studied. Then, the effect of different ratios of cations and free radicals on the adhesion force was studied. Moreover, the curing degree was investigated. Finally, the accuracy and mechanical properties were tested. The results show that when the cationic content is 70% and the free radical content is 30%, the obtained adhesion force is the lowest, and mechanical properties, as well as surface quality of the printed samples, are optimal. More specifically, 540 mm/h printing speed, 2.9% low volume shrinkage, 61.37 MPa tensile strength, and 92.42 MPa bending strength can be achieved. The aforementioned can contributed to expanding the application of 3D printing.

A numerical study on the effect of CO2 addition for methane explosion reaction kinetics in confined space

To explore the influence of the CO2 volume fraction on methane explosion in confined space over wide equivalent ratios, the explosion temperature, the explosion pressure, the concentration of the important free radicals, and the concentration of the catastrophic gas generated after the explosion in confined space were studied. Meanwhile, the elementary reaction steps dominating the gas explosion were identified through the sensitivity analysis. With the increase of the CO2 volume fraction, the explosion time prolongs, and the explosion pressure and temperature decrease monotonously. Moreover, the concentrations of the investigated free radicals also decrease as the increase of the CO2 volume fraction. For the catastrophic gas, the concentration of the gas product CO increases and the concentrations of CO2, NO, and NO2 decrease as the volume fraction of CO2 increases. When 7% methane is added with 10% CO2, the increase rate of CO is 76%, and the decrease rates of CO2, NO, and NO2 are 27%, 37%, and 39%, respectively. If the volume fraction of CO2 is constant, the larger the volume fraction of methane in the blend gas, the greater the mole fraction of radical H and the lower the mole fraction of radical O. For radical OH, its mole fraction first increases, and then decreases with the location of peak value of 9.5%, while the CO concentration increases with the increase of the methane concentration. For all the investigated volume fraction of methane, the addition of CO2 reduces the sensitivity coefficients of each key elementary reaction step, and the sensitivity coefficient of reaction promoting methane consumption decreases faster than that of the reaction inhibit methane consumption, which indicates that the addition of CO2 effectively suppresses the methane explosion.