Thermal Activation Method Research Articles

Effect of different activating agents on carbon derived from Tinospora cordifolia for EDLC application

Abstract The effect of two activating agents namely phosphoric acid (H3PO4) and iron (III) chloride (FeCl3) is investigated, in activation of carbon obtained from Tinospora cordifolia. The structural and morphological properties of the synthesized activated carbons were investigated using X-ray diffraction, scanning electron microscopy, Raman spectroscopy, and Brunauer–Emmett–Teller analysis. A notable yield of ∼60 % of the activated carbons was obtained using a simple and cost-effective approach of chemical activation followed by the thermal activation method. The electrochemical properties of the activated carbons were studied for electric double-layer capacitor application. The electrochemical impedance spectroscopy, galvanostatic charge–discharge and cyclic voltammetry studies revealed superior charge transfer properties of the carbon activated with H3PO4. The capacitor comprising carbon activated with H3PO4 electrodes shows higher specific capacity of 58 F g−1 at 1 A g−1 than that of carbon activated with FeCl3 (37.5 F g−1). The optimized capacitor delivers superior power density and energy density of 2 kW kg−1 and 28.33 W h kg−1, respectively.

Preparation of high-labeled graphene oxide by tritium thermal activation method for application in the betavoltaic cell of a nuclear battery

Possibility of tritium introduction into graphene oxide (GO) by tritium thermal activation method was demonstrated. It has been established that, in order to obtain the highest possible specific radioactivity, thin films of GO with a thickness of 5.6 mg/m2 must be treated with tritium atoms. The experiment provided at 77 K showed a number of advantages. Under these conditions, the specific activity of [3H]GO of 2.6 Ci/mg was reached when calculated by the mass of the initial GO (0.7 Ci/mg if purified to remove the labile tritium). Specific energy release in [3H]GO with such specific activity is 22.3 W/kg, which is enough for its application as a component of an atomic battery.

Study on the hydration characteristics, mechanical properties, and microstructure of thermally activated low-carbon recycled cement

Based on the thermal activation method, utilizing fine particles of waste concrete to prepare low-carbon recycled cement (RC) is currently one of the research hotspots. Based on existing literature research results, this paper identifies four calcination temperature conditions (120, 450, 750, 1000 ℃) and uses replacement rates of 10 %, 30 %, 50 %, 70 %, and 100 % of RC to replace ordinary Portland cement (OPC).The main physical properties, hydration characteristics, mechanical properties, and microstructure of RC are studied. The study elucidated the influence of RC thermal activation temperature, replacement rate, fineness, and age on its hydration characteristics, mechanical properties, and microstructure, establishing a macro-micro correlation for RC and revealing the mechanism of improvement in mechanical properties of thermal-activated RC. The research indicates that in the initial stage of hydration, RC exhibits a relatively fast hydration rate, with higher initial total heat release than OPC. Hydration products include internal hydration products (formation of C-(A)-S-H gel) and external hydration products (formation of plate-shaped AFm). Furthermore, RC exhibits a faster hydration rate at a hot activation temperature of 750°C, with CH and C-S-H gel transforming into the highly hydrated α´L-C2S, forming a denser microstructure at an early stage. Moreover, at a replacement rate of 30 %, the compressive strength of cement mortar reaches its optimum at 28 days, achieving 13.81 MPa, equivalent to 60.7 % of OPC cement mortar, with a 66.67 % reduction in carbon emissions. Microstructure analysis reveals that when the temperature reaches 1000°C, excessive combustion of RC leads to the formation of low-reactivity C2AS and β-C2S, resulting in a decrease in macroscopic mechanical properties. Additionally, increasing the fineness of RC significantly enhances its rehydration capability, especially as the age increases. This study is of great significance for the preparation of green cement-based composite cementitious materials.

Rheological behavior and microscopic characteristic of electromagnetic thermal activated crumb rubber and SBS modified asphalt

Rubber activation provides a feasible approach for the preparation of high-content rubber modified asphalt without increasing the complexity of the production process. The electromagnetic thermal activation method was used for crumb rubber. The high dosage (30 % mass ratio of neat asphalt) activated crumb rubber and SBS (1.2 % mass ratio of neat asphalt) modified asphalt (ARMA) was prepared. The neat asphalt (NA) and 20 % non-activated crumb rubber modified asphalt (RMA) constituted the control group. Storage stability, rheological behavior, and microscopic properties tests were conducted to evaluate the performance differences of them. The rheological behavior of RMA and ARMA was superior to NA. The electromagnetic thermal activation method fragmented rubber particles into numerous disordered small particles, thereby expanded the contact area with asphalt. This resulted in the storage stability of ARMA significantly better than that of RMA. The cross-linked wrinkles were generated by the combined effect of SBS modifier and activated crumb rubber, which enhanced the rheological, anti-fatigue, and elastic behavior. Both RMA and ARMA exhibited high-temperature PG grades of 82˚C. At 70°C, ARMA retained the capability to endure Extremely Heavy Traffic Grade conditions. At a strain level of 2.5 %, ARMA exhibited a 178 % increase in fatigue life compared to RMA. The crumb rubber was dispersed within the RMA and ARMA. Both ARMA and RMA did not exhibit the obviously bee-structure. However, ARMA exhibited a stronger polymer network. Moreover, both the carbonyl index and sulfoxide index of ARMA were lower than those of RMA and NA. The activation process improved the compatibility between rubber and asphalt, and realized the high value utilization of waste rubber.

Study on the microscopic characteristics and hydration mechanism of thermo-alkali activated electrolytic manganese residue geopolymers

As a form of solid waste, electrolytic manganese residue (EMR) exhibits low reactivity, high sulfate content, and exceeds the standards for heavy metals. To address these drawbacks, a high-temperature thermal activation method was employed to enhance its reactivity and remove pollutants. The study investigated the physicochemical properties and leaching toxicity of EMR under different thermal activation conditions. Additionally, the thermally activated EMR was utilized in the preparation of geopolymer material, and the influence of EMR activation temperature, EMR content, sodium silicate content, and molar ratio on the mechanical properties, hydration mechanism, microstructure, and leaching toxicity of the EMR geopolymers was analyzed. The results indicated that after activation in the temperature range of 0–1200°C, the active content of silica-alumina in EMR increased, sulfate decomposition occurred, and the leaching of Mn2+ and NH4+-N decreased to 21.24 and 0.576 mg/L, respectively. When the activation temperature reached 1200°C, the compressive strength of the geopolymer, prepared with 50 % EMR, 50 % granulated blast furnace slag (GBFS), 30 % sodium silicate, and a molar ratio of 1.2, could reach 53.2 MPa at 28-day. Under activation in the range of 0–800°C, ettringite was abundant in the geopolymers, providing strength support. With activation in the range of 800–1200°C, the geopolymers became denser, exhibiting flaky and agglomerate gels. A diffraction peak appeared at 20°-40°(2θ) corresponding to C-(A)-S-H and N-S-A-H gels. Due to the slow depolymerization-polymerization kinetics of the EMR geopolymer and high sulfate content, the heat release rate and cumulative heat were significantly lower than ordinary portland cement (OPC). In the structure of EMR geopolymer, Mn2+ replaced Na+ and Ca2+ in the silicoaluminate structure or chemically bonded with anionic groups to the geopolymer. Simultaneously, Mn2+ participated in the formation of the EMR geopolymer gel, encapsulating within the gel. Therefore, the leaching of pollutants from EMR geopolymers met the standards of GB8978–1996.

Preparation of high-performance bitumen carbon-based microwave absorbing materials from different coal bitumens toward efficient treatment of industrial waste bitumen

The increasing development of communication technology and electromagnetic pollution have accelerated the research and optimization of electromagnetic microwave absorbing materials. There are few studies and reports on the creation electromagnetic microwave absorbing materials from industrial waste, despite the abundance and promise of research preparing of microwave absorbing materials utilizing sustainable resources from biomass. Herein, we prepared carbon-based microwave absorbing materials GCB-800, HTCB-800, and CDLB-800 using three different industrial solid waste bitumens, namely, coal direct liquefaction bitumen, high-temperature coal bitumen, and globular coal bitumen, as raw materials by using the thermal activation method. Due to the excellent porous carbon skeleton structure and the Fe2O3 contained in its internal ash after the heat treatment, which enhances the internal dielectric properties, the CDLB-800 was found to perform very well at the filler amount of 10 wt% obtained minimum reflection loss (RLmin) is −52.41 dB at 10 wt% filler and matched thickness d = 2.1 mm, and the effective absorption bandwidth (EAB) is 4.88GHz, with 87.14% absorption for X-band in the 2-18GHz. This work not only promotes the development of the comprehensive utilization of solid waste in this field, effectively reduces the burden of solid waste on the environment, but also points out the direction for the development of microwave absorbing materials in the future.

Preparation of High-Labeled Graphene Oxide by Tritium Thermal Activation Method for Application in the Betavoltaic Cell of a Nuclear Battery

The possibility of tritium introduction into graphene oxide (GO) by tritium thermal activation method was demonstrated. It was established that, in order to produce the highest possible specific radioactivity, thin films of GO with a thickness of 5.6 mg/m2 must be treated with tritium atoms. The experiment conducted at 77 K showed a number of advantages. GO was processed with tritium atoms, the resulting specific activity of [3H]GO reached 2.6 Ci/mg in term of the weight of the initial GO (0.7 Ci/mg after removal of the labile tritium). Specific energy release of [3H]GO with this specific activity is 22.3 W/kg, which is quite sufficient for its application as a component of a nuclear battery.

Effect of Thermal Activation on the Mineralogical Structure of Magnesium Slag

Magnesium slag's production process is similar to the Portland cement production process. The raw material used is carbonate-containing dolomite, and is calcined in a rotary kiln at 850-900 oC. Afterwards, ferrosilicon and fluorite raw materials are added to the calcined material, they are ground together and turned into pellets, and then they are reduced at a temperature close to the firing temperature of Portland cement clinker (1250-1350 oC) to obtain crown magnesium and magnesium slag. The reduction time of pellet material in reduction furnaces is 12 hours. During this period, almost all of the magnesium minerals in the mixture material are reduced and taken as crown magnesium metal. The remaining material, described as magnesium production slag (reduction furnace waste), consists of Alite (C3S), Belite (C2S), Celite (C3A) and C4AF minerals contained in Portland cement clinker. Some of the minerals contained in Portland cement clinker in the rotary kiln are formed at temperatures below 1400 °C, which is the clinker firing temperature. The only difference other than the firing temperature is that after the Portland cement clinker is fired in the rotary kiln, the clinker is cooled rapidly, increasing the alite (C3S) crystals formed in its structure and preventing the alite minerals from turning back into belite (C2S) minerals. This study produced magnesium slags at different temperatures (1200-1350 oC) by thermal activation method in an industrial environment. The Bogue and XRD methods calculated the mineral phase amounts of the products produced.

Thermal activation mechanism and activity evaluation of lithium slag: Insights from simulated hydration

Lithium slag (LS), a by-product of lithium extraction process, is usually stacked on the surface, occupying a significant amount of land area and leading to various environmental concerns. In this study, the pozzolanic activity of LS was improved by the thermal activation method, and its hydration reaction and hydration products were studied under simulated hydration conditions. The changes of macroscopic and microscopic appearance, particle size, chemical composition and chemical bonding of LS were studied at different thermal activation temperatures (0–1100 °C). Subsequently, the activation effects of LS at different temperatures were preliminarily assessed using a dissolution tests, and its hydration process and products were investigated under simulated hydration conditions. Finally, thermally activated LS was used to prepare cement mortar. The results indicated that spodumene decomposition raised the amorphous phase content in LS, thereby enhancing its pozzolanic activity. However, it is important to note that the activity of the amorphous phase in calcined LS was relatively poor and its hydration reaction proceeded at a slow pace. The presence of sulfate in LS was critical for enhancing the 7-d compressive strength of cement mortar. The amorphous phase was contributed to the later strength development of LS-PC mortar. LS activated at 600–700 °C significantly improved the early strength of cement mortar while ensuring better strength development. After 90 d of curing, the compressive strength of LS600 achieved 70 MPa. By understanding these key findings, the amount of LS in cement-based materials can be maximized to improve the comprehensive utilization rate of LS. However, due to the high SO3 content in LS, the influence of LS on the volumetric stability of the cement-based material is still a subject that necessitates further research.

Tritium labeling vancomycin and studying its adsorption on nanodiamonds

Procedure of tritium labeling vancomycin using tritium thermal activation method has been developed. The influence of target mass on the specific and total radioactivity was revealed. [3H]vancomycin was used for studying its equilibrium adsorption on nanodiamonds as well as its number that tightly bonded with surface and didn’t remove with water. It was found that adsorption from aqueous solution results in tightly bonded vancomycin with nanodiamonds that didn’t removed with water. Application of 0.028 M phosphate buffer (pH 6.7 and 2.7) leads to the equilibrium adsorption growth as much as one and a half times, while vancomycin number in the adsorption complex with nanodiamonds after washing with water was significantly reduced. Such behavior of vancomycin is due to the presence of phosphate-ions that contribute to vancomycin adsorption, but are removed during washing with water. Molecular mechanics simulation allows us to suggest the formation of multiple hydrogen bonds for formation of a durable adsorption complex of vancomycin with nanodiamonds.

Advancing PFAS characterization: Enhancing the total oxidizable precursor assay with improved sample processing and UV activation

Per- and polyfluoroalkyl substances (PFAS) encompass over 9000 chemicals utilized in various industrial and commercial applications. However, the quantification of PFAS using standard commercial analytical methods is currently limited to <50 selected compounds. To address this issue, the total oxidizable precursor (TOP) assay was developed, allowing for the oxidative conversion of previously undetectable PFAS precursors into measurable PFAS. This study investigated different sample processing methods to address post-oxidation PFAS loss identified in literature. Using PFOS as a probe molecule, up to 50 % loss of PFOS was identified during sample work-up. It was determined that the use of mass-labelled PFOS and methanolic acetic acid to chemically quench the sample post-oxidation improved PFOS recovery and allowed for correction of any remaining PFOS loss. The use of ultraviolet (UV) light was then investigated as an activator in contrast to the standard thermal activation method. A comparative evaluation was conducted to assess the recovery and conversion of perfluorooctanoic acid (PFOA), PFOS, and 6:2 fluorotelomer sulfonate (6:2 FTS) using both the heat-activated and UV-activated TOP assays. Results demonstrated that the UV-activated TOP assay achieved complete (100 %) oxidation of 6:2 FTS within 7.5 min, resulting in a total yield of generated perfluorinated carboxylic acids (PFCAs) at 108 ± 8 %. The study concluded by investigating the UV-activated TOP assay for its application on various aqueous film forming foam (AFFF) formulations and two AFFF samples drained from military aircraft rescue firefighting vehicles (ARFFVs). Analysis of these AFFF samples were supported by high resolution mass spectrometry and an expanded analytical suite, identifying several fluorotelomer precursors. The findings of this study provide compelling evidence that modifications in sample processing, work-up procedures, expansion of initial PFAS calibration standards, and UV-activation methods enhance the TOP assay, positioning it as a more reliable and quantitative analytical tool for PFAS characterization.

Effects of alkali activation and hydrothermal processes on the transformation of fly ash into Al-substituted tobermorite fiber

By choosing two sample fly ash with different chemical compositions and calcium-bearing mineralogical phases, this article explored the influence of calcium-bearing minerals in fly ash and hydrothermal methods on the synthesis of tobermorite fiber. It was found that fly ash with more than 20% calcium oxide content easily decomposed and transformed into 9 Å and 11 Å tobermorite fiber, with the tobermorite content exceeding 30%, under the conditions of hydrothermal solution without alkali and 1 h reaction time. It was demonstrated by FTIR spectrogram and solid NMR analysis results that calcium-bearing mineral is a significant factor which can trap most of Al2O3 in the fly ash, preventing it from soaking up into the lattice of tobermorite, and also inhibiting the substitution of Si by Al. A thermal activation method was designed to enhance the transformation process of fly ash with lower calcium concentration by a similar mechanism to calcium action.

Melamine-Assisted Thermal Activation Method for Vacancy-Rich ZnO: Calcination Effects on Microstructure and Photocatalytic Properties.

Defect engineering is considered an effective method to adjust the photocatalytic properties of materials. In this work, we synthesized the vacancy-rich ZnO rods with (100) planes via the melamine-assisted thermal activation method. A high concentration of oxygen vacancies was successfully introduced into non-polar oriented ZnO rods by calcination. The effect of oxygen vacancy on the photocatalytic properties of non-polar-oriented ZnO rods was investigated. Raman and XPS spectra revealed the formation of oxygen vacancies in the ZnO. The results showed that the growth habit and defects in ZnO can be controlled by changing the ratio of ZnO to melamine. The higher ratio of ZnO to melamine led to more amounts of (100) planes and oxygen vacancies in ZnO, and it reached the highest when the ratio was 1.2:1. When the ratio was 1.2:1, ZnO exhibited a high methyl orange degradation rate (95.8%). The differences in oxygen vacancy concentration and non-polar planes were responsible for the improvement in photocatalytic performance. ZnO exhibited good stability and regeneration capacity. After recycling four times, the degradation rate was still at 92%. Using the same method, vacancy-rich α-Fe2O3 was obtained. This work could offer a new and simple strategy for designing a photocatalyst with oxygen vacancies.

Process characterization and pretreatment of container and drum cleaning industry wastewater using a heat‐activated persulfate oxidation process

AbstractThe aim of this study was to treat wastewater from washing, cutting or crushing of intermediate bulk containers (IBCs), steel drums and plastic drums, using the sulfate radical‐based oxidation method. In this study, it was planned to make the wastewater suitable for activated sludge treatment by applying neutralization after a sulfate radical‐based oxidation process. Samples were taken from the industry three times to study these treatment processes. To determine the optimum conditions in the study, chemical oxygen demand (COD), removal efficiency was calculated, and optimum temperature, optimum time, and optimum persulfate dose were determined. Since the washing is done with hot water in the industry, the thermal activation method was used for the activation of persulfate. In the results of the study, COD removal efficiency, and total organic carbon (TOC), biochemical oxygen demand (BOD), total nitrogen (TN), total phosphorus (TP), and potentially toxic metal(s) removal efficiency was measured in three wastewater samples. According to the results of the study, the temperature at which the best COD removal efficiency was observed was 70°C, the COD/S2O82− ratio was 1:2, and the contact time was 5 h. As a result of the study, it has been revealed that such wastewater can be given to the activated sludge after sulfate radical‐based oxidation and neutralization in the same existing reactor instead of the existing FeCl3 process.

Molten-salt-assisted synthesis of single-atom iron confined N-doped carbon nanosheets for highly efficient industrial-level CO2 electroreduction and Zn-CO2 batteries

The development of convenient and highly efficient synthetic route to fabricate single-atom catalysts anchored on N-doped carbon nanosheets remains a big challenge for CO2 electrochemical reduction (CO2RR). Herein, we develop a one-step molten-salt-assisted synthesis combined with temperature-programmed thermal activation method to fabricate Fe single-atom supported on N-doped carbon nanosheets (FeNC NSs) for CO2RR. In a flow cell, CO partial current density of FeNC NSs-1000 up to 147.9 mA cm-2 at − 0.66 V with a high turnover frequency above 1 × 105 h-1 is achieved. Experimental results reveal that the active site was the center Fe atom coordinated with four N atoms, accelerating the formation of *COOH intermediate and thus accounts for its superior CO2-CO conversion activity. Theoretical calculations further manifest that the pyrrolic N in second coordination sphere reduces the energy barrier of rate-limiting step and promotes the electron transfer capacity. Moreover, the FeNC NSs-1000 is applied as cathode to rechargeable Zn-CO2 battery, exhibiting high CO selectivity and superior stability.

Tritium Thermal Activation Method. Features of Application, Modern Achievements, and Further Development Prospects

Tritium Thermal Activation Method. Features of Application, Modern Achievements, and Further Development Prospects

Thermal Activation of Coal Gangue with Low Al/Si Ratio as Supplementary Cementitious Materials

To effectively utilize coal gangue (CG) with low Al/Si ratio, the thermal activation method was used. The activated CG, as supplementary cementitious materials (SCMs), was added into ordinary Portland cement (OPC) to study its physical properties. The XRD results show that CG undergoes a phase transition from kaolinite to metakaolinite during activation. The NMR tests reveal that the low polymerization state Q3 is continuously broadened, and the Al coordination gradually changes from Al VI to Al V and Al IV. The CG particles are scale-like and glassy with a loose structure. By mixing the activated CG (under 800 °C) with cement (mass ratio = 3:7), the water demand of normal consistency increases by 7.2% and the initial and final setting times extend by 67 min and 81 min, respectively. The rough surface and loose structure of activated CG are the main factors contributing to the higher water demand of normal consistency. The micro-aggregate effect of the activated CG reduces the contact rate between the cement particles and water, and the interparticles, thus slowing down the process of hydration reaction, and leading to longer setting times.

An effective activation method for industrially produced TiFeMn powder for hydrogen storage

This work proposes an effective thermal activation method with low technical effort for industrially produced titanium-iron-manganese powders (TiFeMn) for hydrogen storage. In this context, the influence of temperature and particle size of TiFeMn on the activation process is systematically studied. The results obtained from this investigation suggest that the activation of the TiFeMn material at temperatures as low as 50 {\deg}C is already possible and that an increase to 90 {\deg}C strongly reduces the incubation time for activation, i.e. the incubation time of the 90 {\deg}C/90 {\deg}C sample is about 0.84 h while ~ 277 h is required for the 50 {\deg}C/50 {\deg}C sample. Selecting TiFeMn particles of larger size also leads to significant improvements in the activation performance of the investigated material. The proposed activation routine makes it possible to overcome the oxide layer existing on the compound surface, which acts as a diffusion barrier for the hydrogen atoms. This activation method induces further cracks and defects in the powder granules, generating new surfaces for hydrogen absorption with greater frequency, and thus leading to faster sorption kinetics in the subsequent absorption-desorption cycles.

The effect of capsulated nanosilica-epoxy healing agents on the self-healing ability of glass fibers-epoxy composites under mechanical loading

In this study, the effect of using an epoxy healing agent containing silica nanoparticles instead of the neat epoxy healing agent on the self-healing ability of glass fibers/epoxy composites under the flexural, tensile and shear loadings was assessed. For doing this, in the first step, the silica nanoparticles (0, 1, 2 and, 3 wt.%) were dispersed into the ethyl acetate/epoxy healing agent. Then, these mixtures were encapsulated with the urea-formaldehyde polymer by an in-situ polymerization method. Finally, the glass fibers/epoxy composite containing 14 wt.% microcapsules along with 2 wt.% NiCl2(imidazole)4 catalyst were fabricated. To understand how the mechanical-healing behaviors of these composites under the various mechanical loads, these composites were destructed with a quasi-static penetration test for the creation of delamination damage. The healing process was done by the thermal activation method. The obtained results showed that the highest healing efficiency under the flexural, tensile and shear loads belonged to the composite containing 1 wt.% nanosilica into the healing agent, which were 89.8, 87.8, and 156.8%, respectively. The hackles of microcapsules, reduction in the thickness of microcapsules, formation of nanocomposite healing shell and the agglomeration of silica nanoparticles on the healed area were the influence factors on the healing ability of these composites. This work can give a view for healing the microcracks into composite structures by nanocomposite healing agents, which have the higher healing ability and better performance under mechanical loads than conventional healing agents.

Degradation of 1,4-dioxane by sono-activated persulfates for water and wastewater treatment applications

This paper presents a hybrid advanced oxidation process (AOP) based on sonocavitational activation of persulfate (PS) for degradation of 1,4-dioxane during wastewater treatment. Application of sono-cavitation effectively convert PS to radical species demonstrating synergistic effect by increasing the reaction rate and reducing the required energy for activation. It is economically feasible and deployed alternative to the direct thermal activation method. A single and two-stage injection of PS were compared to eliminate self-scavenging effects related to excess of oxidant in system. A GC-MS analysis was used to determine the degradation products of dioxane and to propose the degradation mechanism. The studies revealed that the degradation was significantly enhanced by the addition of PS at molar ratio of oxidant to pollutant 4 with a two-stage injection. Under optimal conditions at US density of 105 W/cm2, dioxane with an initial concentration of 100 mg/L was completely degraded in 120 min.