Thermogravimetric Analysis Experiments Research Articles

Experimental analyses of CO2 sequestration potential in mineralized fly ash and its efficacy in mitigating coal spontaneous ignition risks in underground mine goafs

To effectively utilize fly ash solid waste and realize fly ash resource utilization, carbon sequestration and emission reduction, as well as mine fire prevention and suppression, this paper analyses the components of fly ash by X-ray fluorescence spectrometer (XRF), rheological experiments, the CO2 sequestration experiments by the mineralization of fly ash, thermogravimetric analysis experiments, and flame-retardant property experiments. Additionally, the changes in the physical structure and morphology of fly ash before and after mineralization were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The carbon sequestration capacity and fluidity of fly ash slurry, as well as the ability of mineralized fly ash slurry to inhibit spontaneous coal combustion are comprehensively investigated. The research results indicate that CO2 is sequestered as calcite on the fly ash surface after mineralization. The optimal CO2 sequestration capacity of fly ash is 65.12 kg/t when 0.5 mol/L NaHCO3 is used as an additive. The fluidity of mineralized fly ash slurry is greater than that of fly ash slurry, and the lower the water-cement ratio is, the worse the fluidity. Mineralized fly ash slurry with a water-cement ratio of 3:1 has a strong carbon sequestration capacity and high fluidity, making it suitable for preventing coal spontaneous ignition in mine goafs. Mineralized fly ash slurry exhibits a regular trend where the better the mineralization effect, the lower the CO release during the low-temperature oxidation stage of coal, and the higher the cross-point temperature. Mineralized fly ash slurry has a stronger ability to inhibit spontaneous coal combustion than does ordinary fly ash slurry.

The oxidation of carbon nanostructures imaged by electron microscopy: Comparison between in-situ TEM and TGA experiments

The development of a model of carbon oxidation has engaged researchers for decades. Yet many outstanding questions remain due to the inability to experimentally study the details of the oxidation. Today, novel techniques such as environmental transmission electron microscopy (ETEM), allowing for in-situ nanoscale observations of the oxidation process, can help illuminate some of these questions. In this study of few layers graphene (FLG), multi-walled carbon nanotubes (MWCNTs), buckminsterfullerene (C60), and nanodiamonds (NDs) oxidizing in temperatures up to 1100 °C and we analyze the importance of nanostructure for the thermal stability of nanocarbons. The study was complemented with thermogravimetric analysis (TGA) and the experiments were in good agreement with oxidation rates increasing sharply with temperature and the thermal stability of the materials MWCNTs, FLG, C60 and NDs in descending order. Based on the direct nanoscale visualization obtained in the ETEM the materials can be divided into two overall categories: materials with low strain sp2-bonds (FLG and MWCNT); and materials with high strain sp2-bonds (C60) or sp3-bonds (NDs). For materials in the first category, it is possible to identify several different phenomena as their oxidation rate increases as a function of temperatures whereas materials in the second category appear to be more influenced by extrinsic factors such as the electron beam and by structural transformation upon heating. This study clearly shows the value of adding ETEM results to traditional TGA investigations since it gives both a complementary and more detailed information about the dynamic oxidation process.

Joule Heating in Controlled Atmospheres to Process Nanocarbon/Transition Metal Oxide Composites and Electrodes.

Composites of nanocarbons and transition metal oxides combine excellent mechanical properties and high electrical conductivity with high capacitive active sites. These composites are promising for applications such as electrochemical energy conversion and storage, catalysis, and sensing. Here, we show that Joule heating can be used as a rapid out-of-oven thermal processing technique to crystallize the inorganic metal oxide matrix within a carbon nanotube fabric (CNTf) composite. We choose manganese oxide and vanadium oxide as model metal oxides and show that the Joule heating process is rapid and enables accurate control over the temperature and phase transitions. Next, we use thermogravimetric analysis and Joule heating experiments in controlled atmospheres to show that metal oxides can actually catalyze thermal degradation and reduce the thermal stability of the CNTs, which could limit processing of many oxides. We solve this by using a reducing hydrogen atmosphere to successfully extend the Joule processing window and thermal stability of the CNTf/metal oxide composite to ∼1000 °C.

Slow pyrolysis of Agave americana L. fibers: Analysis of kinetics and thermodynamics using the coats-redfern method at different heating rates

This study employed thermogravimetric analysis (TGA) alongside the Coats-Redfern method (CRM) to investigate the thermal degradation's kinetics and thermodynamics of fibers extracted from the flower stalk of Agave americana (FSAA). We explored FSAA fibers' thermal behavior across varying heating rates (HRs) to elucidate complex reaction mechanisms and estimate critical parameters. TGA experiments at 5, 10, and 20 °C/min HRs reveal a multi-step breakdown process supported by solid coefficients of determination (R2 > 0.99). Activation energy values, ranging from 83.6 to 210.1 kJ/mol, vary with HR, providing insights into thermal decomposition kinetics. Thermodynamic parameters, including variations in entropy (ΔS), Gibb's free energy, and enthalpy, shed light on spontaneity and energy transfer during the process. Negative ΔS values suggested reduced disorder during thermal decomposition. This study represented a novel investigation into the thermal behavior of fibers extracted from the FSAA for the first time, using CRM in conjunction with TGA. Through comprehensive analysis, we elucidated the kinetics and thermodynamics of FSAA fiber degradation across various HRs. Our findings shed light on the intricate reaction mechanisms underlying FSAA fiber decomposition, providing valuable insights for potential applications in biofuel production and composite materials.

Cellulose Nanofiber/Polyethylene Glycol Composite Phase Change Thermal Storage Gel Based on Solid-gel Phase Change

In this paper, cellulose nanofiber (CNF)/ polyethylene glycol (PEG) composite aerogel phase change materials (CNPCMs) were prepared utilizing porous carrier support and freeze-drying. The solid-liquid phase change to solid-gel phase change was realized, which solved the problems of PEG flow, leakage, and shape instability. The physical properties and chemical compatibility of CNPCMs were studied, and the results showed that CNPCMs ensured the overall structure stability through internal hydrogen bonding, and they were only a physical bond with each other without chemical reaction. With the increase in PEG content, the thermal conductivity of CNPCMs increased from 0.22 W/m·K to 0.33 W/m·K. The thermal exposure experiment and thermogravimetric analysis (TGA) experiment have shown that CNPCMs have good shape stability at 75 ℃ and good thermal stability below 320 ℃. In summary, the experimental results indicated that the maximum content of PEG in CNPCMs was 78 % with an optimal content of 66.7 %. The sample corresponding to the optimal content was CNPCM2 with an enthalpy of 167.9 J/g for melting and 146.1 J/g for solidification. As a thermal storage material with good thermodynamic performance, CNPCM2 has enormous potential in the storage of solar collectors.

Application of fume silica nanoparticles to improve high-temperature rheological performance of terminal blend rubberized asphalt

This study aims to evaluate the impact of fume silica nanoparticles (FSNPs) on the high-temperature rheological properties of terminal blend rubberized asphalt (TBRA). In this study, FSNPs were utilized to modify TBRA asphalt with three different CR contents (30%, 40%, 50%). The micro-morphology of FSNPs was observed through Scanning Electron Microscopy (SEM) experiments. The effects of FSNPs on the high-temperature rheological properties of TBRA were assessed using temperature sweep tests, Multiple Stress Creep Recovery (MSCR), and rotational viscosity tests. Furthermore, the influence of FSNPs on the chemical and thermal properties of TBRA was analyzed through Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) tests. Rheological tests and SEM results indicate that FSNPs can effectively enhance the high-temperature elasticity, fatigue resistance, and deformation resistance of TBRA binders. This improvement is attributed to the unique branched network structure of FSNPs, which plays a pivotal role in enhancing the elasticity within the TBRA asphalt matrix. Additionally, the degradation of TBRA's low-temperature performance due to FSNPs is minimal. Considering the optimal viscosity for FSPN-modified TBRA, recommended ratios are: TB30/6%, TB40/4%, and TB50/2%. FTIR and TGA results demonstrate that the modification of TBRA by FSNPs is primarily physical blending, and the addition of FSNPs enhances the thermal stability of TBRA.

Preparation of chitosan‐based macromolecular synergistic antioxidants containing hindered phenolic and secondary amine structures and its effects on thermo‐oxidative aging of styrene‐butadiene rubber/silica composites

AbstractIn this study, chitosan (CS)‐based macromolecular synergistic antioxidant CS‐UC‐TDAA containing carbon–carbon double bond, hindered phenol, and aromatic secondary amine was prepared by using CS,10‐undecenoyl chloride (UC), p‐aminobenzoic acid (AA), 3,5‐di‐tert‐butyl‐2‐hydroxybenzaldehyde (TD) via esterification, Schiff base reaction, and acylation reaction. The molecular structure of CS‐UC‐TDAA was characterized by fourier transform infrared, 1H NMR, and elemental analysis. The effects of macromolecular synergistic antioxidant CS‐UC‐TDAA, small molecular antioxidant TDAA, commercial antioxidant 4020, and butylated hydroxytoluene (BHT) on the antiaging properties of styrene‐butadiene rubber (SBR)/SiO2 composites were systematically studied by accelerated thermo‐oxidative aging test, thermogravimetric (TG) analysis, and methanol Soxhlet extraction experiment. The experimental results show that CS‐UC‐TDAA has more outstanding thermo‐oxidative aging resistance, thermal stability, and solvent extraction resistance in SBR/SiO2 composites than TDAA, 4020, and BHT. The macromolecular synergistic antioxidant CS‐UC‐TDAA endows SBR/SiO2 composites with more durable antiaging performance, which is attributed to the synergistic antioxidant effect of its hindered phenol and aromatic secondary amine groups. Additionally, its resistance to migration and extraction is facilitated by the crosslinking of the carbon–carbon double bond with the rubber and its substantial molecular weight.

Preparation and characterization of pH-responsive metal-polyphenol structure coated nanoparticles

In this paper, tannic acid (TA) and Fe3+ were added to form a layer of metal-polyphenol network structure on the surface of the nanoparticles which were fabricated by zein and carbon quantum dots (CQDs) encapsulating phlorotannins (PTN). pH-responsive nanoparticles were prepared successfully (zein-PTN-CQDs-FeIII). Further, the formation of composite nanoparticles was confirmed by a series of characterization methods. The zeta-potential and Fourier transform infrared spectroscopy data proved that electrostatic interaction and hydrogen bonding are dominant forces to form nanoparticles. The encapsulation efficiency (EE) revealed that metal-polyphenol network structure could improve the EE of PTN. Thermogravimetric analysis and differential scanning calorimetry experiment indicated the thermal stability of zein-PTN-CQDs-FeIII nanoparticles increased because of metal-polyphenol network structure. The pH-responsive nanoparticles greatly increased the release rate of active substances and achieved targeted release.

Preparation of amine functionalized micro-mesoporous silicon adsorbent from fly ash and its kinetic characteristics of CO2 adsorption/desorption process

Micro-mesoporous silicon materials were prepared using silicate filtrate produced from fly ash as a silicon source. Then, the micro-mesoporous silica material was used as the carrier and amine compounds as modifiers to prepare a micro-mesoporous CO2 adsorbent. Afterwards, the structural properties, surface groups, thermal stability of micro-mesoporous silicon materials and micro-mesoporous CO2 adsorbent were studied. The results reveal that the micro-mesoporous CO2 adsorbent maintains the same micro-mesoporous structure as the micro-mesoporous silica material. And the thermal stability temperatures of adsorbent is below 383 K. Later, the CO2 adsorption performance and kinetic characteristics of adsorption process were studied through thermogravimetric analysis (TGA) and adsorption column experiments. The results indicated that the optimal CO2 adsorption capacity of 2.31 mmol/g-adsorbent was achieved at 343 K, and the adsorption capacity remained basically unchanged after 10 adsorption/desorption cycles. Dynamics studies have shown that the Avrami fraction model fits the CO2 isothermal adsorption curve very well, and the fitting results reveal that the intra-particle diffusion dominates the speed of the adsorption process. Additionally, the Yasyerli deactivation model can perfectly fit the CO2 adsorption breakthrough curve, and the fitting results indicate that the CO2 adsorption process is the deactivation process of the adsorbent. Finally, the adsorption/desorption kinetic simulation parameters can be used for the design and optimization of CO2 adsorption and desorption processes in industry.

Use of a high-entropy oxide as an oxygen carrier for chemical looping

One mixed oxide with 5 cations in equimolar proportions in the sublattice, to fulfil high-entropy oxide (HEO) criteria, has been developed and investigated as oxygen carrier for chemical looping combustion processes. As far as we know, nobody has explored this class of material for chemical looping combustion. Material is prepared by direct mixing of five metal oxides (CuO, Mn2O3, Fe2O3, TiO2, MgO), followed by calcination at 1000, 1100 and 1200 °C for 6 h in air. XRD characterization provides strong evidence that the synthesized oxygen carriers possess the hallmark properties of HEO, and SEM-EDX analysis shows an overall homogeneous metal distribution. Materials have one main cubic phase with the empirical formula MnCuMgFeTiO7, dominating under all conditions. One of the key objectives of this study is achieved, reduce chemical stress during redox cycles. Oxygen transfer capability is investigated by thermogravimetric analysis and batch fluidized bed reactor experiments for different fuels and atmospheres. Mass-based oxygen transport capacities for lattice oxygen and oxygen uncoupling are around 5.5 wt% and 1.1 wt%, respectively. This work opens up a new dimension for the future preparation of oxygen carriers for chemical looping processes, since the vast compositional space of HEO provides opportunities to tune both chemical and physical characteristics.

Effect of Polyethylene Pyrolysis Oil Hydrotreatment on the Pt/Al2O3 Catalyst: Experimental Characterization.

The dramatic increase in plastics production, coupled with a low recycling and recovery rate, has been a major challenge for sustainable practices and combating climate change. Hydrotreatment processing to upgrade fuel oils is a well-known process in the petroleum industry. In this work, we aim to investigate the catalyst properties before and after the hydrotreatment of pyrolysis oil derived from plastics, namely, linear low-density polyethylene, as no such report is available in the literature. Granular and powder forms of the Pt/Al2O3 catalyst were used in this study with characterization methods executed as such: transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and IR-RIS. XRD data show that the crystallinity of the catalyst support was unaffected by the hydrotreatment without any residues left, as the characteristic diffraction peaks were indicated for the crystalline phase of the support as 37.4, 39.8, 46.3, and 67.3°. In addition, the TGA experiments revealed that the carbon deposition on the spent catalyst was higher, as indicated by the higher weight loss (15.359%) compared to the fresh catalyst sample (11.43%). XPS analysis showed that the carbon deposition is more intense on the granular spent catalyst, as the intensity of the peaks is some 15 times greater than the peaks from the fresh catalyst. Also, compared to the observed peaks of the powder catalyst, less coke is formed. The band at 1624.05 cm-1 from the IR-RIS spectra was attributed to a shifted C=O band from the coke formation. The extension of these investigations using different catalysts to improve their characteristics and performance and to inhibit coke deposition will contribute to the incorporation of such processes in industry as well as the cost of fuels.

MEMS Resonant Beam with Outstanding Uniformity of Sensitivity and Temperature Distribution for Accurate Gas Sensing and On-Chip TGA.

Micromechanical resonators have aroused growing interest as biological and chemical sensors, and microcantilever beams are the main research focus. Recently, a resonant microcantilever with an integrated heater has been applied in on-chip thermogravimetric analysis (TGA). However, there is a strong relationship between the mass sensitivity of a resonant microcantilever and the location of adsorbed masses. Different sampling positions will cause sensitivity differences, which will result in an inaccurate calculation of mass change. Herein, an integrated H-shaped resonant beam with uniform mass sensitivity and temperature distribution is proposed and developed to improve the accuracy of bio/chemical sensing and TGA applications. Experiments verified that the presented resonant beam possesses much better uniformity of sensitivity and temperature distribution compared with resonant microcantilevers. Gas-sensing and TGA experiments utilizing the integrated resonant beam were also carried out and exhibited good measurement accuracy.

Preparation and performance study of OPC-MF-PEG microcapsules based on strong antioxidant groups against spontaneous coal combustion

In order to solve the problem of spontaneous combustion of coal in the air-mining area, flame-retardant microcapsules were prepared by in-situ polymerization. OPC-MF-PEG flame-retardant microcapsules were prepared by selecting proanthocyanidin (OPC) as the core material of the microcapsules, polyethylene glycol-modified Melamine resin (hereinafter referred to as modified resin) as the shell. The microcapsules were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), stability analysis experiments, thermogravimetric analyzer (TG), and other experiments in terms of their surface morphology, dispersion, encapsulation, pyrolysis, and other properties. On this basis, the microcapsules were mechanically mixed with coal samples to prepare chemically inhibited coal samples. The effects of microcapsules with different core-to-wall ratios on the spontaneous combustion characteristics of coal were investigated by TG experiments. The results showed that the flame retardant effect was best when the core-to-wall ratio was 3:1. According to the analysis of the combustion experiment results, the CO concentration of the coal samples treated with microcapsules was reduced by 57.5% and 22.5% compared with that of the pure coal and OPC-treated coal samples.

2-(((4-(Trifluoromethyl)quinolin-6-yl)amino)methyl)phenols: Synthesis, optical properties, thermal, and electrochemical behavior

This paper describes the synthesis, photophysical properties, and thermal and redox behavior of a novel series of nine selected 2-(((2-substituted-4-(trifluoromethyl)quinolin-6-yl)amino)methyl)phenols (4). These phenols contain 2-Me, 2-aryl, or 2-(2-furyl)-quinolines and 5-OMe, 4-Br or 4-NO2 substituted amino methylphenol cores assembled in the scaffolds of 4. Optimized yields of 51–98 % were obtained when the reactions of the respective imines 3 were conducted with sodium borohydride in ethanol at 80 °C for 30 min. The structural characterization of compounds 4 was performed by multinuclear NMR, FTIR, and HRMS techniques. Thermogravimetric analysis experiments indicated that the majority of the compounds obtained exhibited high thermal stability at temperatures over 200 °C. The UV–Vis steady-state and time-resolved fluorescence emission, TD-DFT calculations, and redox analyses were used to determine the photophysical and electrochemical properties of the studied derivatives, revealing a correlation between the electronic effects of the substituents attached to the quinoline and phenol cores and the evaluated parameters.

Study on the pyrolysis characteristics and char gasification kinetics of pre-separated automobile shredder residues

Automobile shredder residue (ASR) is a typical solid waste produced by the end-of-life automobile industry. The pyrolysis and gasification of ASR are effective methods to achieve reduction and resource utilization. By means of thermogravimetric analysis and fixed-bed experiments, the distribution as well as physicochemical properties of five typical ASR pyrolysis products after pre-sorting were systematically investigated, and the gasification kinetics of their pyrolysis char under CO2 as well as steam were also studied. Results showed that the pyrolysis of ASR was basically completed at 500°C, and the pyrolysis gas yield increased significantly with temperature. The tar contained mainly poly-benzene rings with carbon atoms C11–15 and their derivatives. At high temperatures, the structure of pyrolysis char tended to become more ordered, with small functional group such as - OH, - NH, - CH3, - CC -, and - COOH fracturing. The residual amounts of heavy metals such as Cr, Pb, and Ni in pyrolysis char were mostly exceed 45%, which were significantly affected by the type of heavy metals, pyrolysis temperature and material type. Hydrogen production from steam gasification accounted for up to 65%, and the gasification reactivity was better than that of CO2 gasification. The activation energy (E) calculated through shrinking core model (SCM) and random pore model (RPM) was 38.81–105.44 kJ/mol and 39.53–98.56 kJ/mol, respectively, which provided a good fit to the gasification kinetics in two gasification atmospheres. This study provides detailed data for the ASR pyrolysis and gasification technology, which is an important reference value for ASR research.

An Experimental Study and Numerical Simulation Analysis of Thermal Oxidation Characteristics Based on Kinetic Parameters in Heavy Oil Reservoirs

In situ combustion (ISC), an efficient and economical method for enhancing heavy oil recovery in high-pressure, high-viscosity, and thermally challenged reservoirs, relies on the kinetics of crude oil oxidation. Despite an increased focus on kinetic models, there is a gap in understanding how oxidation kinetic parameters impact ISC effectiveness in heavy oil reservoirs. This study addresses this by selecting heavy oil samples from the G Block in the Liaohe oilfield and the M Block in the Huabei oilfield and conducting ramped temperature oxidation (RTO), pressure differential scanning calorimetry (PDSC), and thermogravimetric analysis (TGA) experiments. RTO detailed the thermal conversion process, categorizing oxidation into low-temperature oxidation (LTO), fuel deposition (FD), and high-temperature oxidation (HTO) stages. PDSC and TGA provided thermal characteristics and kinetic parameters. The feasibility of fire flooding was evaluated. Using CMG-STARS, an ISC model was established to analyze the impact of kinetic parameter changes. Activation energy significantly affected coke combustion, while the pre-exponential factor had a notable impact on cracking reactions. The recommended values for activation energy and the pre-exponential factor are provided. This study not only guides fire flooding experiments but also supports field engineering practices, particularly for in situ combustion in heavy oil reservoirs.

Electrospinning for producing antifungal nanofibers consisting of prochloraz/hydroxypropyl-γ-cyclodextrin inclusion complex

Prochloraz is an extensively used imidazole fungicide in agriculture, but low water solubility limits its application. In the present study, inclusion complex nanofibers of prochloraz and Hydroxypropyl-γ-Cyclodextrin (prochloraz/HPγCD-IC-NF) were prepared by electrospinning method. The results of various characterization experiments indicated that prochloraz was effectively encapsulated in the cyclodextrin cavity to form inclusion complex nanofibers. Phase solubility study demonstrated that HPγCD had a significant solubilization effect on prochloraz. In 10 mM HPγCD solution, the solubility of prochloraz was increased about 2.68 times. Thermogravimetric analysis experiments indicated the beginning thermos-decomposed temperature of prochloraz in prochloraz/HPγCD-IC-NF was raised by 31℃ (from 281℃ to 312℃). The molecular simulation visually showed the best state and the most stable model of prochloraz entering the cyclodextrin cavity. In addition, the fungal inhibitory activity of prochloraz/HPγCD-IC-NF against Gibberella was 4.559 times to that of prochloraz. In conclusion, the preparation of inclusion nanofibers can improve the water solubility, thermal stability and antifungal activity of mimosine, which has the potential to reduce environmental damage in agricultural applications.

Effect of water vapor on the oxidation of heavy fuel and vacuum residue oil in a TGA

The effect of water on the oxidation of two residual fuel oils (heavy fuel oil (HFO) and vacuum residual oil (VRO)) was investigated in a thermogravimetric analyzer (TGA). The oxidation process in humid atmosphere was investigated by monitoring the mass loss profiles in a wide range of conditions. The TGA experiments cover temperatures range from ambient to 800 °C, heating rates of 5, 10 and 15 °C min−1, and various oxygen and water vapor concentrations were studied. The results show a noticeable effect of humidity on the oxidation process of the two fuels, especially in the fuel deposition region, where the presence of water increased the mass decay. Kinetic analyses were performed using a model-based method, Coats and Redfern to investigate the reaction schemes in different temperature regimes. First order, 1-D diffusion and assumed random nucleation and growth mechanisms were found to capture the oxidation of HFO and VRO in different temperature regimes. Apparent kinetic parameters estimated also exhibited a noticeable effect of water vapor on the oxidation of both fuels. The interpretation of the data obtained from mass loss profiles aided in understanding the physical processes that can contribute to the efficient utilization of HFO and VRO.

Co-combustion characteristics and kinetics of sludge/coal blends in 21%–50% oxygen-enriched O2/CO2 atmospheres

This research investigated the thermogravimetric analysis (TGA) and combustion kinetics of sewage sludge and Australian sub-bituminous coal and their blends with different mixing ratios (sludge/coal = 100/0, 80/20, 50/50, 20/80, 0/100 by weight) under air atmosphere (O2/N2 = 21/79 by volume), oxy-fuel combustion (O2/CO2 = 21/79, 25/75, 35/65, and 50/50 by volume), and pyrolysis (pure N2 atmospheres). The gaseous products that evolved from the TGA experiments were also analyzed using a Fourier transform infrared (FTIR) spectrometer under pyrolysis conditions. Results showed that the mixed fuel with higher coal blending ratio had higher ignition temperature, lower burnout temperature and larger combustion characteristic index. Furthermore, TGA–FTIR experiments of the 20 % sludge + 80 % coal blended fuel under nitrogen atmospheres showed more gasification components in pure coal than in sludge. The combustion kinetics analytical results via the Flynn–Wall–Ozawa method indicated that the larger the conversion degree, the smaller the obtained activation energy value. Under the oxy-fuel combustion conditions, when the oxygen concentration increased from 21 % to 50 % for the 20 % sludge + 80 % coal blended fuel, the ignition and burnout temperatures decreased, and the combustion characteristic index increased nearly three times. Oxygen enrichment can clearly improve combustion characteristics and flammability.

Photocatalytic degradation of SBX in mineral processing wastewater with hollow CdS/MWCNTs nanocomposites

In this study, a novel hollow sphere CdS/MWCNTs composite photocatalytic material was prepared by hydrothermal method and was first used for the photocatalytic degradation of sodium butyl xanthate (SBX) in sulfide mineral processing wastewater. The morphology structure and photocatalytic properties of hollow sphere CdS/MWCNTs composite catalyst were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), ultraviolet-visible diffuse reflectance spectroscopy (UV–vis DRS), thermogravimetric analysis (TGA) and photocatalytic activity experiments. The results showed that 15 mg CdS/MWCNTs with the 5 % MWCNTs doping amount possessed the highest photocatalytic degradation efficiency for SBX which the degradation rate reach 99 %. The hollow sphere structure and addition of MWCNTs obviously improved the migration and separation of photogenerated electrons (e−) and holes (h+) of pure CdS, leading to high photocatalytic efficiency.