Raw Coal Research Articles

Scheme evaluation method of coal gangue sorting robot system with time-varying multi-scenario based on deep learning.

The rapid advancement of artificial intelligence and robot technology has spurred the proposal and innovation of a coal gangue sorting robot system (CGSRS) paradigm. The time-varying raw coal flow (TVRCF) with multi-scene and full working conditions affects the gangue queue. Configuring the CGSRS scheme correctly is combative. The field environment puts forward higher requirements for the time complexity of the CGSRS multi-task allocation strategy. Therefore, this paper proposes a scheme evaluation method of the CGSRS with time-varying multi-scenario based on deep learning. Firstly, the gangue queue data set of multi-scene and full-condition TVRCF was obtained according to the belt speed, the maximum coal flow, and the uncorrelated nonlinear changes of coal flow and gangue content. The CGSRS scheme is established based on robot number and rule combination, and the multi-task allocation strategy is adjusted to generate the labels of the gangue queue. Then, the RGB sample set is established based on the labels of the gangue queue. The CGSRS scheme evaluation model is trained based on DenseNet. Finally, the CGSRS scheme evaluation method was designed to realize the prediction of a random gangue queue. In this paper, the CGSRS scheme evaluation model, the stability of the solution, and the comparison of methods are carried out. Experimental results show that the solution of the CGSRS scheme evaluation model is accurate and stable. The time complexity is significantly reduced and very stable. The CGSRS scheme evaluation method is applied to the CGSRS multi-task allocation problem, and the stability of the solution is not affected by the data. It is significantly better than the multi-task allocation strategy. The proposed method is the first attempt to apply deep learning to a multi-task allocation problem in CGSRS.

Dynamic Strain Rate Effect and Macro–Micro-Fracture Mechanism of Raw Coal Under True Triaxial Conditions

Dynamic Strain Rate Effect and Macro–Micro-Fracture Mechanism of Raw Coal Under True Triaxial Conditions

Insights of Physicochemical Structure Changes of Bituminous Coal with Acidification-assisted Controlled Electric Pulse through SEM, XRD and FTIR

Controlled electric pulse (CEP) cracking coal effectively enhances its permeability, but a high coal breakdown voltage (BV) can result in technical difficulties. To address this problem, the method of using HCl solution to improve the electrical conductivity of coal was proposed. The effects of HCl on coal BV were investigated, and the microstructural changes in coal were analyzed through scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy. Compared with raw coal, the BV of acidified coal decreased significantly. The crushing degree of the coal samples was clearly enhanced with an increasing HCl concentration. Some internal coal minerals were acidified and dissolved, the aromatic layer spacing (d002) increased and the layer sheet stacking height (Lc) decreased, and the crystal structure was damaged. When acidified coal was broken down, numerous internal pores and cracks appeared, active coal groups were shed, the aliphatic hydrocarbons and oxygen-containing functional group contents increased, surface activity was reduced, and the hydroxyl content was reduced, which was conducive to rapid gas desorption. Acidification effectively reduces the BV of coal and improves the cracking and permeability enhancement effect of coal by CEP action.

Study on the influence of aerosol atomization by ultrasonic atomization on coal spontaneous combustion

ABSTRACT Influenced by the complex environment and the nature of process materials in goaf, the prevention and control of spontaneous combustion of coal (CSC) in the deep part of goaf were facing many difficulties. To investigate the performance of ultrasonic atomized aerosols, a series of atomization experiments were conducted using a self-developed ultrasonic atomization device. The main conclusions are as follows: under the same atomization conditions, the atomized particle sizes of several inhibitors (except PAS-W) are concentrated in the <8 μm range, with a content of more than 88%, indicating that the aerosol particles produced by ultrasonic atomization are small in size and uniform in distribution. Compared with water and MgCl2 inhibitors, aerosol particles produced by PAS-W are less likely to pass through the voids of the coal body, and have poorer permeability and diffusivity. As the temperature increases, the viscosity and surface tension of the inhibitor decrease, and the percentage of aerosol particles with particle size <8 μm produced by ultrasonic atomization is more than 88%, indicating that the atomization effect is improved. After increasing the temperature, the contact angle between PAS-W inhibitor and coal reduces from 54.7° to 40.8°, and the wettability is better. Compared with raw coal, the final temperature of the PAS-W aerosol treated coal sample is delayed 21.86°C, and has significant retarding property. When the wind speed is 3 m/s, the effect of PAS-W aerosol particle generation, permeability, and particle size distribution is the best. The results of the study are of great significance in improving the ultrasonic atomized aerosol fire prevention technology and realizing large-scale CSC prevention in goaf.

Study on the Thermal Effect of Spontaneous Combustion of Coal-Based Activated Carbon By-Products Oxidized and Carbonized Powders

ABSTRACT To investigate the spontaneous combustion thermal effect of the by-products oxidized powder (OP) and carbonized powder (CP) produced during the preparation of coal-based activated carbon (CBAC). First, the changes in composition and pore structure of OP and CP compared with raw coal (RC) were measured by coal quality analysis and nitrogen adsorption experiments. The ability of OP and CP to physically adsorb oxygen was determined. Then, differential scanning calorimetry (DSC) was used to study the whole process thermal effect of the spontaneous combustion of OP and CP. Finally, the thermal effect of OP and CP during low-temperature oxidation process was further explored by the C80 micro-calorimeter, and the thermodynamic characteristics were also probed. The results show that the content of fixed carbon and carbon elements in OP and CP are significantly greater than that in RC, which makes the pore structure of both complicated. In addition, the total pore volume, average pore size, and specific surface area of OP and CP are greater than that of RC, which is more conducive to the physical adsorption of oxygen by both. No transition platform is caused by the decomposition of intermediate products on the DSC curve of CP. The characteristic temperatures of CP (except T D10) are lower than that of OP, indicating that the spontaneous combustion reaction of CP started earlier than that of OP. However, part of the combustible substance of CP was consumed in the dry distillation process, leading to the thermal release and maximum thermal release rate being smaller than that of OP. The apparent activation energy (E a) of stages H2 and H3 in the low-temperature oxidation process of OP is 75.04 and 11.42 kJ mol−1, while that of CP is 83.11 and 30.91 kJ mol−1. The threshold of CP entering stages H2 and H3 is higher than that of OP. Nevertheless, from the pre-exponential factor (A), the low-temperature oxidation process of CP is more rapid.

Preparation of PVA/EG-WG gel foam and its inhibition of coal spontaneous combustion

In order to solve the shortcomings of existing gel foam such as poor stability, low strength and weak water retention capacity, a novel gel foam was prepared. The optimal ratio of this gel foam was determined in this experiment, and its inhibition performance and inhibition mechanism were analyzed. The results showed that the gel foam had the optimal performance when the mass fractions of foaming agent, foam stabilizer, gelling agent, cross-linking agent, Polyvinyl alcohol (PVA) and Ethylene glycol (EG) were 0.8 %, 1 %, 8 %, 2.2 %, 3 % and 7 %. After the gel foam action, the peak CO content in the oxidation process of coal samples decreased by 56.17 %, the average inhibition rate increased by 18.67 %, and the activation energy before and after the dry cracking temperature increased by 3.08 kJ and 9.20 kJ. The characteristic temperature points were greatly improved compared with those of the raw coal, which effectively slowed down the exothermic rate of coal oxidation. Compared with the traditional gel foam, PVA/EG-WG gel foam can achieve the effect of coal spontaneous combustion inhibition by means of inhibition and oxygen isolation, cooling and chemical reaction, etc.

Wind speed effect on infrared-image-based coal and gangue recognition with liquid intervention in LTCC

The commitment to achieving carbon neutrality by 2060 makes the clean transition of fossil energy production inevitable in China. As the primary fossil energy source, China produced approximately 4.66 billion tons of raw coal in 2023. Among them, in the fields of mining engineering and environmental science, the accurate recognition of gangue (one of the environmental pollutants produced by coal combustion is black-gray solid waste) from coal is crucial because it is a key step in reducing resource waste and environmental pollution. Hence, coal and gangue automatic recognition with high accuracy is very important for intelligent longwall top coal caving (LTCC) mining. A novel approach of “liquid intervention + infrared detection” is introduced to enhance the recognition accuracy when the exterior color of coal and gangue is similar. This study focuses on the infrared image recognition of coal and gangue after liquid intervention under varying wind speed conditions, and optimizes the image processing path. The effect of varying wind speed conditions on the recognition accuracy of coal and gangue after liquid intervention was analyzed, and the optimal wind speed range was determined. The morphological evolution characteristics of droplets under varying wind field conditions were studied by COMSOL two-phase flow interface. The results show that with the increase of wind speed, the surface contour of coal is gradually clear, and the overall recognition accuracy is also improved. When the high wind speed is 1.55 m/s, the recognition accuracy reaches 99.89%, and the recognition accuracy of other wind speed regions is also above 90% (within 7s). In addition, the numerical simulation can maintain the volume fraction of the droplet in a short time under the constant flow wind flow field, thus inhibiting the phenomenon that the recognition accuracy decreases with time. The simulation results are in good agreement with the physical experimental phenomena, which proves the reliability of the numerical simulation. This study is of great significance to the recognition of coal gangue types with low identification characteristics in LTCC, so as to ensure the primary economic benefits, ecological environment safety and sustainable development of coal mines.

Fabrication and characterization of low-cost ceramic membranes from coal fly ash and natural sand

Coal fly ash, an industrial solid waste product, and natural sand, a commonly available and inexpensive natural material, were used to fabricate ceramic membranes that are both affordable and sustainable. These ceramic membranes were fabricated by the uniaxial compaction technique using a manual hydraulic pressing machine. The effects of various fabrication parameters such as the sintering temperature and the amount of natural sand utilized, on the properties of the resulting ceramic membranes were extensively evaluated. X-ray fluorescence (XRF) analysis of the starting materials confirmed the presence of SiO2 and Al2O3, two key inorganic materials required for the fabrication of ceramic membranes. Heavy metals present in the raw coal fly ash were leached out prior to the fabrication process. The coal fly ash and natural sand were mixed in different proportions and the fabricated ceramic membranes were characterized using Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope (SEM), X-ray diffraction (XRD), Energy-dispersive X-ray spectroscopy (EDS), and Thermogravimetric analysis (TGA). The properties of the optimized membranes were further studied to ascertain their mechanical strength, chemical stability, porosity, water absorption, water permeability, and shrinkage behaviour. The membrane fabricated with 20 wt% sand content and at 1000 °C sintering temperature had pore size of 0.64 µm and 34.7 % porosity, exhibited good mechanical strength (7.71 MPa), and exceptional chemical stability. The membrane also showed a remarkable water permeability of 32.23 L/m2/h. This study showed that natural sand and coal fly ash can be efficiently employed to develop a multifunctional filtration membrane with adjustable properties that can be utilized in water purification.

Microwave-induced alterations in the structure of coals at different metamorphic stages

Despite the global trend toward decarbonization, coal continues to play a significant role in energy production, as current renewable energy sources cannot fully meet the increasing global energy demand. The main objective of decarbonization is to reduce greenhouse gas emissions, especially carbon dioxide. Enhancing coal usage efficiency can help decrease these emissions. Electromagnetic activation of bituminous coal is already employed for dehydration, ash removal, desulfurization, and improving the grinding process of raw coal. This research aims to study the specifics of coal electromagnetic activation using microwave radiation and its effects on the physical and chemical processes occurring in coals at different metamorphic stages. The results suggest that this electromagnetic treatment leads to the destruction of hydroxyl groups and the formation of free hydrogen. Coals at higher metamorphic stages heat up faster due to their higher structural density. Coals at lower metamorphic stages take longer to heat up and require more processing time to be effective, while lower power levels are necessary to avoid mechanical breakdown. Activation time and coal particle size are significant factors; their optimal combination provides the maximum effect. These findings contribute to optimizing microwave treatment parameters for different coal types, potentially enhancing coal utilization efficiency and reducing environmental impact.

Effects of outdoor air pollution on hospital admissions from cardiovascular diseases in the capital city of Mongolia

Cardiovascular diseases (CVD) are one of the primary causes of morbidity worldwide, while ambient air pollution (AAP) is a major contributor to CVD. This study is the first study that aimed to compare the differences in AAP concentrations and acute effects on the risk of admissions from CVD, ischaemic heart diseases (IHD), and stroke before and after introducing the new type of coal briquette in Ulaanbaatar, Mongolia. We collected daily hospital admission records, air quality and meteorology data between January 1, 2016 and December 31, 2022. The relative risks (RRs) of cause-specific hospitalisations associated with daily concentrations of AAP were estimated by a time-stratified case-crossover analysis with conditional Poisson distributed lag models. Overall, acute exposure to the pollutants, except for O3, was positively associated with an increased risk of all admissions. For each interquartile range (IQR) increase in PM2.5, PM10, SO2, NO2 and CO, the risk of CVD admissions increased by 0.5% (RR=1.005; 95% CI: 0.998, 1.012) at lag0, 2.9% (RR=1.029; 95% CI: 1.014, 1.044), 2.5% (RR=1.025; 95% CI: 1.010, 1.040), 4.1% (RR=1.041; 95% CI: 1.016, 1.068) and 0.3% (RR=1.003; 95% CI: 0.995, 1.012) at lag01, respectively. Subgroup analyses showed greater risks of CVD admissions for women and people aged <65 years, in the cold season, and after the raw coal ban period. During the cold winter season, Ulaanbaatar’s AAP levels remained higher than the World Health Organization’s guidelines, regardless of consuming the new coal briquettes. Adopting alternative efficient methods to improve air quality and associated health outcomes is necessary.

Preparation and growth mechanism of high-quality multilayer graphene from simulated coal pyrolysis gas via chemical vapor deposition

Chemical vapor deposition (CVD) of graphene from coal pyrolysis gas provides new ways for both large-scale graphene preparation and high value-added utilization of coal. However, green, efficient and continuous preparation of high-quality multilayer graphene with both good uniformity and ideal structure characteristic remains a great challenge. Herein, we first investigated the influence of main carbonaceous species (CH4, C2H6, C3H8, CO2, and CO) in coal pyrolysis gas on the quality of CVD graphene products. The experimental results indicated that CO2 and CO have little effect on the growth of graphene, while methane as carbon source is conducive to obtain ideal graphene materials, propane and ethane could also influence structural defects and layer number of graphene products remarkably. On this basis, we designed a mixed gas of methane, ethane, and propane with optimized ratio as simulated coal pyrolysis gas, and successfully prepared high-quality multilayer graphene products on nickel foam from the as-designed simulated coal pyrolysis gas by CVD method. Notably, with a CH4:C2H6:C3H8 ratio of 2:1:1, the graphene products prepared from simulated coal pyrolysis gas outperformed that of raw coal pyrolysis gas in terms of physical structure, layer number, and quality uniformity. The corresponding I2D/IG value reached 0.97. The graphene growth process and mechanism were investigated and discussed macroscopically and microscopically. This work is of great significance for the intrinsic understanding of CVD growth of graphene from coal pyrolysis gas, and also inspires an efficient and environmentally friendly avenue for high-throughput, uniform production of high-quality graphene materials.

Kinetic analysis of coal oxidative pyrolysis before and after immersion effect

The oxidative pyrolysis kinetics of coal before and after immersion effect was studied by thermogravimetric experiments. Non-isothermal thermogravimetric analysis data were analyzed at four heating rates of 5, 10, 20 and 30 K/min. Furthermore, temperature-programmed experiments and Fourier-transform infrared (FTIR) spectroscopy were employed to understand the oxidation activity and chemical structure of raw coal and soaked coal. After coal immersion effect, the increase in the content of active functional groups, the increase in the concentration of gaseous products, and the decrease in crossing point temperature during oxidation process all indicate that soaked coal is easier to oxidize and spontaneously combust. Lastly, four model-free methods such as Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Friedman and Kissinger methods are employed to calculate the activation energy (Eα). Kinetic analysis reveals that Eα value obtained by the former three methods significantly depends on the conversion of coal oxidative pyrolysis process, and the average Eα value of soaked coal obtained by four methods is lower than that of raw coal. For the kinetic analysis of coal oxygen adsorption and combustion stages, it is more reliable to adopt the FWO and KAS methods in turn. This research helps to better understand the mechanism of enhanced oxidation activity of soaked coal and optimizes the calculation method of kinetic parameters in different oxidation stages of coal.

Effect of combustion temperature on the unburnt carbon during ammonia co-firing with coal combustion.

Ammonia co-firing with coal seems to be the preferred approach to reduce unburnt carbon in existing pulverized coal-fired power plants. However, some operational conditions such as combustion temperature need to be carefully considered. As such, this study investigated the effect of combustion temperature on the unburnt carbon during ammonia co-firing with pulverized coal. Horizontal tube furnace with ammonia injection was employed and operating at different combustion temperature (800 to 1200 oC). Proximate analysis results showed that the raw coal sample contained 64.2 wt% fixed carbon. Additionally, based on the several analyses employed to assess the effect of combustion temperature efficacy on the unburnt carbon reduction, an effective combustion efficiency was achieved with ammonia co-firing with coal. X-ray fluorescence results revealed that SiO2 for the co-firing experiment decreased from 56.7476 wt% (800 oC) to 45.9423 wt% (1200 oC) while carbon decreased from 20.06 to 18.32 wt%, at the same combustion temperature respectively. X-ray diffraction also revealed a well-defined peak at 2θ = 25o, a graphite characteristic, which decreased significantly with increasing temperature, signifying unburnt carbon reduction. Thus, it can be confirmed that ammonia co-firing with coal can be used to improve the combustion efficiency coal fired power plants.

Study on preparation and performance of bagasse/sodium carboxymethyl cellulose gel for inhibiting coal spontaneous combustion

In order to effectively prevent and control coal spontaneous combustion and improve the safety of coal mining, bagasse carboxymethy cellulose (BCC) prepared from bagasse (BS) and sodium carboxymethyl cellulose (CMC) were used as the substrates. A gel (BCC-CMC) for inhibiting coal spontaneous combustion was prepared using a chemical crosslinking method involving zirconium citrate crosslinking and glucono-delta-lactone (GDL) modification. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were utilized to characterize both the crystal and molecular structure of bagasse and its derived bagasse carboxymethyl cellulose. The results indicated that new carboxymethyl groups were introduced into bagasse during the treatment, facilitating the successful extraction and preparation of sodium carboxymethyl cellulose. The results of viscosity and bonding tests demonstrated that the concentration and dosage of CMC had the most significant influence on the gel viscosity, which remained higher and more stable at room temperature. The coal bonded by the gel coal mixture can effectively seal surface cracks, with a bonding degree of up to 70.72 %. TG-DTG, temperature-programmed oxidation experiment and FTIR analyses revealed that, compared to raw coal, coal samples treated with gel exhibited improved stability, fewer active groups, and fewer oxygen-containing functional groups, effectively inhibiting coal’s low temperature oxidation and reducing the risk of spontaneous combustion. The gel is environmentally friendly, cost-effective, and exhibits good flame retardant properties. This study is of great significance for preventing and controlling coal spontaneous combustion, effectively ensuring the safe production of coal resources and the safety of mine workers, achieving the green sustainable development of the mine.

Effect of pre-oxidation and cooling process on characteristics and mechanism of the coal re-ignition

Based on the engineering background that the sealed fire area is easy to reignite, the reignition characteristics of pre-oxidized coals (POC) after cooling are studied. Predecessors mainly explain this problem from the perspective of pre-oxidation affecting coals pore structure. This paper analyzes the effects of different pre-oxidation temperatures and cooling atmospheres on coal physical and chemical structure. The changes of coals during oxidation-cooling-reoxidation were studied by means of a programmed heating device, low temperature nitrogen adsorption experiment, FTIR and quantum chemical calculation. The results show that the average pore size of the coal cooled in nitrogen at the same pre-oxidation temperature is smaller than that of the coal cooled in dry air, while the spontaneous combustion characteristics of the coal cooled in nitrogen are stronger than those of raw coal, and spontaneous combustion characteristics of coal cooled in air are the opposite. The oxygen-containing functional groups of the coal cooled in nitrogen are pyrolyzed to produce active sites which can exist stably in nitrogen. Then, the rationality of “The active sites tend to be alkyl radical” is analyzed and speculated by molecular orbital theory, and it's found that alkyl radicals can release lots of heat at 30 °C.

Chlorine evolution and char characteristics during pyrolysis upgrading of Xinjiang high chlorine coal

Xinjiang ShaErHu (SEH) coal, characterized by a high chlorine concentration exceeding 1 %, can cause severe chlorine corrosion when directly burned. To utilize this high-chlorine coal in an effective and clean way, specific pretreatments such as low-temperature pyrolysis upgrading are required. In this paper, the changes in tar, pyrolysis gas, combustion characteristics, and chlorine evolution features were analyzed during the low-temperature pyrolysis of SEH coal. The effects of increasing temperature (350 °C, 450 °C, and 550 °C) were studied. The results show that the proportion of aromatic compounds released consistently increases with temperature, reaching a peak of 80 % at 550 °C in the tar. It is noteworthy that chlorine is hardly detected in tar. The percentage of chlorine released in the pyrolysis gas remains relatively stable as the temperature rises from 350 °C to 550 °C, accounting for approximately 17.5 % of the total chlorine. The percentages of water-soluble chlorine in raw coal, char-350 °C, char-450 °C and char-550 °C are 74.3 %, 80.4 %, 82.2 %, and 55.1 % respectively. The majority of the chlorine in the char produced at 350 °C and 450 °C is inorganic, making up 68.9 % and 69.4 %, respectively. In contrast, char generated at 550 °C has 58.4 % chlorine that is primarily organic. About 40 % of the inorganic chlorine is converted to organic chlorine when the pyrolysis temperature is raised to 550 °C. This conversion likely occurs as a result of the inorganic chlorine ions combining with carbon to form C-Cl bonds. In order to effectively prevent high temperature corrosion, high-chlorine coal can be treated by pyrolysis at temperatures between 350 and 450 °C, followed by water washing and burning. This research provides a theoretical foundation for the clean and efficient use of high-chlorine coal.

Triple strategies for process salt reduction in industrial wastewater treatment: The case of coking wastewater

Human activities introduce nutrient elements into wastewater, yet the saline byproducts from treatment are poorly managed. Selecting a low-salt process, without compromising treatment efficacy, is essential for reaching the zero-discharge goal in water treatment. Based on the engineering treatment process of coking wastewater, the source and reduction strategy of salts were studied. The results showed that 73.21 % of the residual salt originated from raw coal, 10.87 % from raw water, and 15.92 % from chemicals, respectively. Triple strategies for process salt reduction (PSR): load salt reduction, technology salt reduction and cyclic salt reduction can bring 0.411 mS/cm·m3, 0.217 mS/cm·m3 and −0.070 mS/cm·m3 salt reduction, and also bring 1.455 CNY/m3, 0.836 CNY/m3 and 0.360 CNY/m3 net present value, respectively. Meanwhile, PSR is also a low-carbon strategy, which will bring about carbon emission reduction of 1.6948 kg CO2-eq/m3, 0.4898 kg CO2-eq/m3 and 1.4082 kg CO2-eq/m3 respectively. The Resource/Carbon source Management-Oxic − Hydrolytic & Denitrification − Oxic (A-OHO) process, incorporating PSR, cuts costs by 27.83–31.66 % and carbon emissions by 18.68–19.54 % compared to conventional wastewater treatment methods. It can be predicted that the PSR in the standard treatment stage can provide a guarantee for the subsequent water reuse and desalination process to reduce project investment and operating costs, and at the same time benefit the macro environment from the aspects of carbon emission reduction and sludge reduction.

Synergetic studies on the thermochemical activation and polyaniline integration on the adsorption properties of natural coal for chlorpyrifos pesticide: steric and energetic studies

Three types of synthetic coal-derived adsorbents were characterized as potential enhanced structurers during the removal of chlorpyrifos pesticide. The raw coal (CA) was activated into porous graphitic carbon (AC), and both CA and AC were blended with polyaniline polymers (PANI/CA and PANI/AC) forming two advanced composites. The adsorption performances of the modified structures in comparison with CA were evaluated based on both the steric and energetic parameters of the applied advanced isotherm model (the monolayer model of one energy). The uptake performances reflected higher capacities for the PANI hybridized form (235.8 mg/g (PANI/CA) and 309.75 mg/g (PANI/AC) as compared to AC (156.9 mg/g) and raw coal (135.8 mg/g). This signifies the impact of activation step and PANI blending on the surface and textural properties of coal. The steric investigation determined the saturation of the coal surface with extra active sites after the activation step (Nm(AC) = 62.05 mg/g) and the PANI integration (Nm(PANI/CA) = 113.5 mg/g and Nm(PANI/AC) = 169.7 mg/g) as compared to raw coal (Nm(CA) = 39.6 mg/g). This illustrated the reported uptake efficiencies of the modified samples, which can be attributed to the enhancement in the surface area and the incorporation of additional chemical groups. The results also reflect that each site can be loaded with 3–4 molecules of chlorpyrifos, which are arranged vertically and adsorbed by multi-molecular mechanisms. The energetic studies (< 40 kJ/mol) suggested the physical uptake of pesticide molecules by dipole bonding and hydrogen bonding processes. The thermodynamic functions donate the exothermic properties of 47reactions that occur spontaneously.

Imidazole ionic liquid effects on coal swelling behavior and pyrolysis characteristics: Experiment and molecular simulation

In view of low-rank coal conventional swelling solvent large pollution and the clean efficient utilization of coal, the effects of imidazole ionic liquid (IL) pretreatment with different anion groups as green solvent on coal thermal expansion and pyrolysis performance were investigated. IL interacts with coal molecules, destroying the hydrogen bonds, resulting coal expansion. Different anion groups have different modification effects, [Bmim]Cl has the best swelling effect, which is 17.37 % higher than raw coal, and the best modification time is 24 h. In addition, IL modification has a catalytic effect on coal pyrolysis, which can significantly reduce the maximum weight loss temperature and increase tar content. Coal solvent pretreatment provides a good theoretical basis for application of swelling and pyrolysis. The reduction of thermochemical reaction temperature not only reduces the content of heavy groups in pyrolysis products, but also provides new ideas for carbon emission reduction.

Investigation of co-combustion characteristics and kinetics of low-ranked coal and hydrochar derived from cow manure

CO2 emission should be reduced by the effective utilization of low-ranked coal in a coal-based power plant based on co-combustion of coal and biomass. This study investigated the co-combustion behavior of lignite and cow manure using three different kinds of samples: raw lignite coal blended with cow manure (CM-L), raw lignite coal blended with hydrochar derived from cow manure (HCM-L), and co-hydrothermal carbonization (Co-HTC) of lignite coal and cow manure (Co-HCML) using thermogravimetric analysis and a hydrothermal carbonization (HTC) temperature of 200 °C for 60 min. The kinetic parameters were calculated and analyzed using the Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods. The combustion characteristics were studied of the various kinds of hydrochar mixed with lignite coal. The results showed that the low-ranked coal improved the fuel properties by increasing carbon content and decreasing sulfur through the HTC processes. The activation energy of Co-HCML was the lowest, which is preferable, and therefore it was recommended as the promising process.