Effect Of Calcination Temperature Research Articles

Effect of Calcination Temperature on Structure Evolution of Hematite Nanoparticles

Abstract This research aims to examine the transition structure of iron oxide, namely from magnetite to hematite, and the impact of calcination temperature on the structural development of hematite nanoparticles. The coprecipitation process was used to extract the magnetite from Indonesian local iron sand. Magnetite was calcined at several temperatures (350, 500, 650, and 800 °C) to produce hematite. Several characterization methods were combined to investigate the structure changes due to the effect of calcination temperature. The synchrotron X-ray diffraction (SRD) and X-ray absorption spectroscopy (XAS) techniques were used to investigate the crystal and local structure, respectively. The Debye-Schrerer equation at the most dominant SRD peak were used to determine the crystallite size. Meanwhile, scanning electron microscopy (SEM) performed to studied the surface morphology. The results of SRD showed that the Fe3O4 and α-Fe2O3 phases are visible in the sample calcined at 350°C, whereas the single-phase α-Fe2O3 was seen at higher temperatures. It was also observed that the crystallinity and crystallite size increased due to the increasing calcination temperature. The crystallite size increased from 9.57 to 29.55, 16.40, 28,48, 29.26, and 29.55 nm for the magnetite, H350, H500, H650, and H800 samples. Meanwhile, XAS fitting data found that higher calcination temperatures increase the interatomic distance but decrease the Debye-Waller factor. It can be concluded that the transformation from Fe3O4 to single-phase α-Fe2O3 was observed at 500oC. A higher calcination temperature of at least 800oC wouldn't change the phase but affect the structure parameters.

Potential Utilization of Loess in Grouting Materials: Effects of Grinding Time and Calcination Temperature

There is a huge reservation of loess in the Shanxi mining area in China, which has great potential for preparing supplementary cementitious materials. Loess was modified via mechanical and thermal activation, and the pozzolanic activity was evaluated using an Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES). Moreover, the workability of grouting materials prepared using modified loess was assessed. The experimental results revealed that the number of ultrafine particles gradually increased with the grinding time, enhancing the grouting performance. The coordination number of Al decreased upon the breakage of the Al–O–Si bond post-calcination at 400 °C, 550 °C, 700 °C, and 850 °C. Moreover, the breaking of the Si–O covalent bond produced Si-phases, and the pozzolanic activity of loess increased. Furthermore, the modified loess was hydrated with different cement proportions. With increasing grinding time, the overall setting time increased until the longest time of 14.5 h and the fluidity of the slurry decreased until the lowest fluidity of 9.7 cm. However, the fluidity and setting time decreased with increasing calcination temperature. The lowest values were 12.03 cm and 10.05 h. With the increase in pozzolanic activity, more ettringite was produced via hydration, which enhanced the mechanical properties. The maximum strength of the hydrated loess after grinding for 20 min reached 16.5 MPa. The strength of the hydrated loess calcined at 850 °C reached 21 MPa. These experimental findings provide theoretical support for the practical application of loess in grouting.

Reaction mechanism, hygroscopic behavior, and properties of aluminum phosphate adhesive

The lack of basic research is a principal reason restricting the widespread application of aluminum phosphate adhesive, such as its reaction mechanism is not yet clear. Herein, we investigate the dissolution behavior of aluminum oxide (Al2O3) in acid aluminum phosphate (AAP) solution and the effects of Al2O3 addition, calcination temperature and phosphorus to aluminum (P/Al) ratio of the AAP solution on the thermal evolution, phase development and hygroscopic behavior of aluminum phosphate adhesive. The dissolution process of Al2O3 in AAP solution is controlled by external diffusion. The thermal evolution of aluminum phosphate adhesives is a complex process that is a function of Al2O3 addition and calcination temperature. Although it is a linear process, many of the reactions are largely coupled and occur simultaneously. The hygroscopic mechanism of aluminum phosphate adhesives is associated to the hydrophilicity of the hydroxyl groups (P–OH). Increasing the calcination temperature and the Al2O3 addition can improve the hygroscopicity resistance properties. Finally, the mechanical and dielectric properties of the quartz fiber cloth reinforced aluminum phosphate matrix composites (SiO2f/aluminum phosphate composites) were also investigated. The results demonstrate that the composites have the characteristics of light weight, high strength, and excellent dielectric properties, suggesting that they have attractive applications in radome materials.

Effect of calcination temperature on structural, morphological elastic and electrical properties of MgO nanoparticles synthesized by combustion method

This study explores the influence of calcination temperature on the properties of MgO nanoparticles (MgO NPs) synthesized via the solution combustion method. Through X-ray diffraction (XRD) and scanning electron microscopy (SEM), structural and morphological changes were investigated. Elastic and dielectric properties were analyzed using computational tools and impedance spectroscopy. Results show that the prepared nanomaterial is belongs to a cubic system and a space group of F m −3 m. Increasing in the calcination temperature (550 °C and 750 °C) enhances crystallinity, reduces defects, and improves structural uniformity. Elastic properties exhibit notable improvements, with Young's modulus increasing from 356.43 GPa for pristine MgO to 364.6 GPa for MgO calcined at 750 °C. Dielectric studies were conducted in the frequency range from 50 to 5 MHz at room temperature. Dielectric analysis reveals enhanced properties, including increased dielectric constant and AC conductivity with rising temperature. The study emphasizes the pivotal role of calcination temperature in tailoring MgO NPs for diverse applications.

One-Step Ethanol Conversion for 1,3-Butadiene Synthesis over Two-Dimensional VMT-SiO2 Nanomesh Loaded with Magnesium and Copper Oxide

A two-dimensional porous silica nanomesh (VMT-SiO2) was used as a carrier to prepare MgO-CuO-based catalysts and tested for one-step ethanol conversion to 1,3-butadiene. The effects of catalyst composition and different calcination temperatures on the reaction performances of the catalysts were mainly investigated. Combining various characterization techniques, such as HRTEM, XRD, FT-IR, and TPD, it was found that the dispersion state of MgO and CuO on the catalyst surface was related to the calcination temperature, which further induced changes in the acid–base properties. A small number of acidic centers and a proper proportion of medium–strong alkaline centers maintained a subtle balance, affecting catalytic performance. A lower total acid/base ratio is more conducive to ethanol conversion and 1,3-butadiene formation. At the same time, the synergistic effect of CuO and MgO promotes the transformation of the intermediate acetaldehyde product, which is the key to ensuring the subsequent aldol condensation and then 1,3-butadiene formation. Among the investigated samples, the CuO/MgO-VMT-SiO2 catalyst calcined at 500 °C exhibited the best catalytic performance, with an impressive ethanol conversion of 47.8% and 1,3-butadiene formation (42.6% selectivity and a space-time yield of 182.0 gC4H6·kgcat−1·h−1).

Effect of Calcination Temperature on Soot Oxidation Activity by Pure and La-doped CeO2 (Ce1−xLaxO2) Synthesized via Orange Peel Extract

Effect of Calcination Temperature on Soot Oxidation Activity by Pure and La-doped CeO2 (Ce1−xLaxO2) Synthesized via Orange Peel Extract

Effects of calcination temperature on the microstructure and magnetic properties of low-temperature-fired Ni0.4Cu0.15Zn0.45Fe1.98O3.97 ferrites

Effects of calcination temperature on the microstructure and magnetic properties of low-temperature-fired Ni0.4Cu0.15Zn0.45Fe1.98O3.97 ferrites

Effect of calcination temperature on structural, optical and photocatalytic properties of calcium titanate (CaTiO3) nanoparticle

In this study, the sol–gel method was used to synthesize calcium titanate (CaTiO3) at different calcination temperatures (400–800 °C). The main objective of this work is to find, using various characterization techniques, how the calcination temperature influences the optical, structural, and photocatalytic properties of CaTiO3. According to the DTA/TGA analysis, 600 °C was the ideal calcination temperature for the synthesis of CaTiO3 nanoparticles. The photocatalytic treatment of simulated wastewater demonstrates its potential application in wastewater treatment. For all calcination temperatures, the percentage of Chemical Oxygen Demand (COD) removed after treatment was 100 % for the initial COD of 700 mg/L, more than 83 % for the initial COD of 5000 mg/L, and more than 71 % for the initial COD of 16000 mg/l.

Bi-metallic zeolitic imidazolate framework (ZIF) derived ZnO/Co3O4 heterostructure: effect of calcination temperature on microstructural and photocatalytic properties

Bi-metallic zeolitic imidazolate framework (ZIF) derived ZnO/Co3O4 heterostructure: effect of calcination temperature on microstructural and photocatalytic properties

Unraveling the structural complexity of and the effect of calcination temperature on calcium phosphates derived from Oreochromis niloticus bones

In this study, the interplay between the structural complexity, microstructure, and mechanical properties of calcium phosphates (CaPs) derived from fish bones, prepared at various calcination temperatures, and their corresponding sintered ceramics was explored. Fourier-transform infrared analysis revealed that the calcined powders primarily consisted of hydroxyapatite (HAp) and carbonated calcium hydroxyapatite, with an increasing concentration of Mg-substituted β-tricalcium phosphate (β-TCP) as the calcination temperature was increased. X-ray diffraction patterns showed enhanced sharpness of the peaks at higher temperatures, indicating a larger crystallite size and improved crystallinity. The ceramics exhibited a significantly larger crystallite size and an increased concentration of the β-TCP phase. Rietveld analysis revealed a larger volume of the β-TCP phase in the ceramics than in their calcined powders; this could be attributed to a newly formed β-TCP phase due to the decomposition of HAp. Extended X-ray absorption fine structure analysis revealed the incorporation of Mg in the Ca2 site of HAp, Ca2 site of β-TCP, and Ca5 site of β-TCP, with a higher substitution of Mg in the Ca5 site of β-TCP at elevated temperatures. The mechanical properties of HAp ceramics can be improved by increasing the calcination temperature because of their improved relative density and dense porous structure at elevated temperatures. This comprehensive investigation sheds light on the phase evolution, microstructural changes, and consequential impact on the mechanical properties of CaPs derived from fish bones, thereby facilitating the development of tailored CaP ceramics for biomedical applications.

The phase-stabilized behavior of Sc2O3–Y2O3 co-doped ZrO2 nanopowders by co-precipitation synthesis

Single stabilizer-doped ZrO2 has drawbacks such as inferior mechanical properties and thermal stability, making it difficult to obtain ZrO2 ceramics with good density and high crystallinity. Thus, it is expected that ZrO2 is doped and modified by two or more stabilizers. In this paper, the Sc2O3–Y2O3–ZrO2 nanocomposite ceramic powders were prepared using ZrOCl2⋅8H2O, ScCl3⋅6H2O, and YCl3⋅6H2O as raw materials and polyvinylpyrrolidone as dispersant. They calcined at diverse temperaturesby the pressureless sintering-assisted co-precipitation method after being pressed into disc shape. Sc2O3 and Y2O3 were added as ZrO2 stabilizers to ameliorate the lack of insufficient mechanical properties and high-temperature stability of ZrO2 ceramics caused by single doping. To study the stability of the phases at high temperatures, the specimens were characterized by TG-DTG, XRD, Raman, SEM, FT-IR, etc. The effects of different pH valuesand different calcination temperatures on the Sc2O3–Y2O3–ZrO2 nanocomposite ceramics were investigated. It was demonstrated that ternary doping has very excellent phase stability. After calcination no monoclinic phase appeared, and the precursor samples were transformed from amorphous to a large amount of tetragonal phases and a few cubic phases. The samples at pH = 10 and calcination temperature of 1000 °C showed the best stabilization, the most uniform grain development, the best crystallinity, the most regular morphology, the highest tetragonal phase content of 89.2 %, the stabilization rate of 94.58 %, and the highest relative density of 98.75 %. The results show that this nanocrystalline powder can be used to prepare high-density nanoceramics. Furthermore, the activation energy for grain growth of Sc2O3–Y2O3–ZrO2 nanocomposite ceramics was calculated as 13.87 kJ/mol. This paper provides a theoretical and experimental research basis for the controlled synthesis of Sc2O3–Y2O3–ZrO2 nanocomposite ceramics using a pressureless sintering-assisted co-precipitation method.

Synthesis and Characterization of Hydroxyapatite/Alginate Composites: Study of pH and Sintering Influenced on the Structural, Morphological, and Clindamycin Release Behavior

The hydroxyapatite/alginate (HAp/Alg) composite was synthesized using an in-situ precipitation route. The effect of pH (8, 9, 10, and 11) and calcination temperature (300, 500, 700, and 900 °C) were studied by characterization techniques such as X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and scanning electron microscopy with energy-dispersive X-ray (SEM with EDAX). XRD results show the hexagonal crystal system of HAp for each pH value and the biphase (HAp and whitelockite) for the sintering temperature at 700 and 900 °C. The FTIR spectra show no impurity peaks. SEM images revealed spherical-like (HAp/Alg-11) and flake-like (HAp/Alg-900) particles with good homogeneity, size, and shape that could be notable for biomedical utilization, such as drug delivery material. Drug loading and release ability of pure HAp, HAp/Alg-11, and HAp/Alg-900 composites have been investigated with clindamycin hydrochloride as the drug model. The maximum clindamycin HCl release from HAp, HAP/Alg-11, and HAp/Alg-900 reached 74.48, 92.75, and 69.65% in the 8th hour. HAp/Alg-11 has the highest release because it has the largest surface area of 162.584 m2/g. Antibacterial test results showed HAp/Alg-11 has antibacterial activity against Staphylococcus aureus and Escherichia coli, confirming that HAp/Alg-11 composite has the potential to be applied as drug delivery.

Catalytic oxidation of formaldehyde by MnOx-decorated anatase TiO2{001}: Investigation of the effect of calcination temperature on catalytic activity and reaction mechanism

The removal of indoor formaldehyde (HCHO) is crucial for human health. The design of highly catalytically active nonprecious metal catalysts has major challenges, and the use of transition metal element modification to improve the catalytic performance is an effective strategy. In this study, the active component Mn was loaded on highly active crystalline anatase TiO2{001}, and the effect of the calcination temperature on the catalytic activity was investigated. The important influence of temperature on the catalyst valence distribution, surface active oxygen species, and content was thoroughly determined by characterization techniques, such as XPS, H2-TPR, and O2-TPD. The catalytic reaction process was further analyzed by in situ infrared technology to determine the reaction intermediates and to clarify the catalyst reaction poisoning mechanism; additionally, a reasonable HCHO catalytic reaction pathway was proposed with the combination of density function theory calculations. In addition, oxygen defects on the catalyst surface were determined by EPR, and based on theoretical calculations, the oxygen defects could further reduce the reaction energy barrier through the Langmuir-Hinshelwood mechanism. By exposing specific crystal surfaces and increasing the number of oxygen defects, the catalytic activity could be effectively improved; based on these results, our study provides a concept for the subsequent development of nonprecious metal catalysts.

The Study on Alkali Fusion-water Leaching of Silicon From Molybdenum Tailings

Taking the molybdenum tailings produced after beneficiation of the Luanchuan molybdenum mine in Henan Province as the research object, the effects of alkali ore ratio, calcination time and calcination temperature on the activation effect of molybdenum tailings, and the effects of leaching time, leaching temperature and leaching liquid-solid ratio on the silicon leaching rate were investigated by using sodium hydroxide alkali melting-water leaching process. The results show that the optimal conditions for activation are as follows: alkali-ore ratio 1.2:1, calcination time 1 h, calcination temperature 700°C. Under these conditions, the concentration of alkali fusion leaching (Si+Al) of molybdenum tailings is 1.396 mg/L. The optimum conditions for leaching are as follows: leaching time 7 h, leaching temperature 45°C, leaching liquid-solid ratio 6: 1. Under these conditions, the leaching rate of silicon can reach 26.88%. During the calcination process, the crystal structure of quartz is destroyed, and sodium hydroxide reacts with quartz at high temperature to form soluble silicate, which improves the activity of molybdenum tailings and increases the dissolution of silicon

Engineering the heterojunction between TiO2 and In2O3 for improving the solar-driven hydrogen production

Nanostructured In2O3 was grown on TiO2 NPs by thermal treatment of the solids mixture of TiO2 with the parent In(OH)3. The effect of calcination temperature in the range between 400 °C and 700 °C was investigated and peculiar changes both in the structure and in the catalytic activity of the TiO2/In2O3 heterostructure were revealed. It was found out that T = 600 °C is the best operating temperature for hydrogen production and in combination with 3.5 wt% In2O3 the H2 production from water reached the value of 3.5 mmol/h.g irradiating in the UV–Vis region. Once 5.0 wt% Cu2O nanoparticles were loaded on TiO2/In2O3, the photocatalytic activity boosted to 9.6 mmol/h.g of H2, overcoming the hydrogen production of pristine TiO2 by a factor of 48. This result can be attributed to the formation of a highly efficient heterojunction that assures a synergistic cooperation among the three semiconductors yielding an improved charge separation and faster charge transport, as evidenced by Mott-Schottky, PL and EIS measures.

Synergistic effect between amorphous ZrO2 modified support and Pd catalyst: Unveiling superlative sulfur resistance and exquisite catalytic hydrogenation performance

The presence of sulfides in the reaction system can seriously affect the stability and activity of the catalysts. In this paper, we compare the impact of introducing varying amounts of the metal oxide ZrO2 on the hydrogenation activity and sulfur resistance of Pd-based catalysts. The study examined the effect of calcination temperature for catalysts and various organic sulfide types on their catalytic performance. We employed multiple techniques to characterize the catalysts, including physical adsorption, TEM, XRD, XPS, H2-TPD, NH3-TPD, and Py-IR. The results revealed that the catalysts achieved 99.9 % conversion and exhibited 99.5 % selectivity towards 4-ethyltoluene when the Pd and Zr molar ratio was 1:5. Furthermore, they could withstand the presence of toxicants for over 10 cycles. The main reason for the difference in activity and stability between catalysts lies in introducing ZrO2 as a promoter. This introduction increases the number of acidic sites and enhances the electronic effect, thereby facilitating the cleavage of H2 by Pd0. The synergistic effect between Pd and ZrO2 decreases the strength of S-Me, impedes sulfide adsorption, and improves the sulfur resistance stability of the catalyst. This work demonstrates that ZrO2-modified Pd-based catalysts have great potential in the anti-sulfur system of olefin hydrogenation.

Evaluation of Impact of Calcination Temperatures on Kola Nut Pod Residue as Catalyst for Biodiesel Synthesis

The research explores the viability of Kola Nut Pod (KNP) residue, derived from kola fruit in West African countries, as a catalyst for biodiesel synthesis. The abundant KNP husk, a byproduct, raises environmental concerns if discarded directly. The study aims to utilize KNP as a biocatalyst to address environmental issues and reduce biodiesel feedstock costs. Applying calcination temperatures from 500 to 900 ℃, the resulting ash undergoes chemical analysis to determine the optimal temperature for catalyst formation. The material undergoes pre-treatment, including drying and grinding, with varied calcination temperatures to obtain ash products. Chemical, elemental, and X-ray Diffraction (XRD) analyses characterize both uncalcined and calcined samples. The uncalcined sample contains SiO2, Al2O3, CaO, MgO, K2O, and other oxides, with CaO as the predominant component. Calcination temperature effects indicate increased SiO2 and Al2O3, while CaO remains stable, presenting KNP as a promising biodiesel catalyst feedstock. Elemental composition analysis identifies potassium as the key catalytic contributor. The CaO content shows an increase from the uncalcined state (29.52%) to 42.81% at 500 and 600°C, and relatively stable at 41% from 700 to 900°C. The elemental composition reveals that potassium is the most abundant element at 31.7%, followed by calcium (17%), and magnesium (7.4%). XRD analysis confirms CaO as the primary compound in calcined KNP ash, with Ca (OH)2 and KCl occurrences. The study offers insights into the optimal calcination temperature for KNP-derived catalysts, underscoring Kola Nut Pod residue's potential as a cost-effective and eco-friendly source for biodiesel production.

Activation of Low-Quality Coal Gangue Using Suspension Calcination for the Preparation of High-Performance Low-Carbon Cementitious Materials: A Pilot Study

Although the calcination-based activation of coal gangue is important for its valorization in the form of cementitious materials, the related works mainly focus on high-quality coal gangue, neglecting its low-quality counterpart. To bridge this gap, we herein conducted the pilot-scale suspension calcination of low-quality coal gangue; explored the effects of calcination temperature, particle size, and O2 content on the phase composition of the calcined product, kaolinite decomposition, decarbonization, and silica/alumina dissolution; and evaluated calcination-product-based cementitious materials. Under optimal conditions (temperature = 875–900 °C; particle size = 39.71–46.84 μm; and O2 content = 12–14%), the carbon content of the calcined product equaled 1.24–1.87 wt%, and the dissolution rates of activated alumina and silica were 77.6–79.5% and 49.4–51.1%, respectively. The 28 d compressive strength (50.8–55.7 MPa) and true activity index (98.8–108.4%) of the cementitious material prepared at a calcination product dosage of 30–38 wt% met the standard of 42.5 grade cement. This study demonstrated the suitability of suspension calcination for the preparation of high-performance low-carbon cementitious materials from low-quality coal gangue, thus providing a basis for further industrialization and technological development.

Selective catalytic reduction of NO with NH3 over copper-manganese spinel oxides at low temperature: effects of calcination temperature and dispersant

Selective catalytic reduction of NO with NH3 over copper-manganese spinel oxides at low temperature: effects of calcination temperature and dispersant

Structural/surface characterization of transition metal element-doped H-ZSM-5 adsorbent for CH3SH removal: identification of active adsorption sites and deactivation mechanism.

CH3SH is a potential hazard to both chemical production and human health, so controlling its emissions is an urgent priority. In this work, a series of transition metal-loaded H-ZSM-5 adsorbents (Si/Al = 25) (Cu, Fe, Co, Ni, Mn, and Zn) were synthesized through the wet impregnation method and tested for CH3SH physicochemical adsorption at 60°C. It was shown that the Cu-modified H-ZSM-5 adsorbent was much more active for CH3SH removal due to its abundant strong acid sites than other transition metal-modified H-ZSM-5 adsorbents. The detailed physicochemical properties of various modified H-ZSM-5 adsorbents were characterized by SEM, XRD, N2 physisorption, XPS, H2-TPR, and NH3-TPD. The effects of metal loading mass ratio, calcination temperature, and acid or alkali modification on the performance of the adsorbent were also investigated, and finally 20% Cu/ZSM-5 was found to have the best adsorption capacity after calcined at 350°C. Additionally, the Cu/ZSM-5 adsorbent modified by sodium bicarbonate could expose more active components, which improved the adsorbent's stability. However, the consumption and reduction of the active component Cu2+ and the accumulation of sulfate during the adsorption process are the main reasons for the deactivation of the adsorbent. In addition, the simultaneous purging of N2 + O2 can effectively restore the adsorption capacity of the deactivated adsorbent and can be used as a potential strategy to regenerate the adsorbent.