Effect Of Calcination Temperature Research Articles

Effect of Calcination Temperatures on Surface Properties of Spinel ZnAl2O4 Prepared via the Polymeric Citrate Complex Method-Catalytic Performance in Glycerolysis of Urea.

In this study, we investigated urea glycerolysis over ZnAl2O4 catalysts that were prepared by using a citrate complex method and the influence of calcination temperatures on the surface properties of the prepared catalysts by varying the calcination temperature from 550 °C to 850 °C. As the reciprocal substitution between Al3+ and Zn2+ cations led to the formation of a disordered bulk ZnAl2O4 phase, different calcination temperatures strongly influenced the surface properties of the ZnAl2O4 catalysts, including oxygen vacancy. The increase in the calcination temperature from 550 °C to 650 °C decreased the inversion parameter of the ZnAl2O4 structure (from 0.365 to 0.222 for AlO4 and 0.409 to 0.358 for ZnO6). The disordered ZnAl2O4 structure led to a decrease in the surface acidity. The ZnAl2O4-550 catalyst had a large specific surface area, along with highly disordered surface sites, which increased surface acidity, resulting in a stronger interaction of the Zn NCO complex on its surface and an improvement in catalytic performance. Fourier transform infrared and thermogravimetric analysis results of the spent catalysts demonstrated the formation of a greater amount of a solid Zn NCO complex over ZnAl2O4-550 than ZnAl2O4-650. Consequently, the ZnAl2O4-550 catalyst outperformed the ZnAl2O4-650 catalyst in terms of glycerol conversion (72%), glycerol carbonate yield (33%), and byproduct formation.

Precipitated calcium oxide nanosize from limestone and blood clam shells

Calcium oxide (CaO) is a product that is needed by various types of industries such as the pharmaceutical, chemical, agricultural and health industries. CaO is generally produced by the calcination method of CaCO3 materials such as calcium carbonate rocks or from various types of shells. The calcination method requires a large amount of energy because the operating temperature is above 1000 C and the resulting calcium oxide product is still micrometer size. This study developed nanosize precipitated CaO from two calcium sources, namely blood clam shells and limestone. For clam shells using hydrochloric acid as a solvent and sodium hydroxide as a precipitating agent, while for limestone using phosphoric acid as a solvent and potassium hydroxide as a precipitating agent. The effect of acidity (pH) and calcination temperature on the characteristics of the precipitated CaO was observed. The blood calm shell produces precipitated CaO 85-92 % with a particle size of 200-250 Nm and the limestone produces precipitated CaO 42-66% with a particle size of 250-300 Nm

Recycling MgO from the waste magnesium oxychloride cement (MOC): Properties, CO2 footprint and reuse in MOC

Recycled magnesia was prepared via using magnesium oxychloride cement (MOC)-based waste as the raw material instead of magnesite through calcination under the temperatures from 600 °C to 1000 °C. The effects of calcination temperature on the components, microstructures, and properties of recycled MgO, and its influence on the performance of MOC containing the recycled MgO were investigated. Results indicated that the reactivity of recycled MgO depended on the calcination conditions, the active MgO content approached 80 wt% through the calcination of MOC-based waste in the temperature range of 700 °C–900 °C. The MOC paste was prepared by using 30 wt% MgO recycled under 800 °C exhibited higher mechanical performance, denser microstructure and more stable volume. The carbon emissions of recycled MgO are 0.49 t/t of magnesia, which is only 31.2% of that emitted by the calcination of magnesite via conventional dry route. This study provides an efficient approach to reducing the consumption of non-renewable natural resources and the generation of construction waste to realize cleaner and sustainable production of reactive MgO.

RECOVERY OF MANGANESE FROM MANGANESE ORE REDUCTIVELY ACID LEACHING PROCESS USING REEDS (IMPERATA CYLINDRICA) AS REDUCING AGENT

Recovery of manganese from manganese ores was investigated by reductive leaching method using reeds as a reductant in the sulfuric acid medium. Cellulose, hemicellulose, and lignin are natural reducing agents which are widely used as reducing agents to recover manganese. Effects of calcination temperature and the holding time calcination on the leaching efficiency of manganese and impurities were examined. The calcination temperature and the holding time calcination have a significant effect on the extraction of manganese. The experimental results demonstrated that the higher the calcination temperature used, the higher the percentage of manganese obtained, namely 79.58% and 87.38%, respectively. The XRD (x-ray diffraction) pattern shows that the manganese phases formed at 700 and 800 °C are Mn3O4 (hausmannite) and Mn2O3 (bixbite), respectively. The morphology in the sample with calcination temperature at 700 °C showed agglomerate- shaped particles and unevenly dispersed. Meanwhile, the sample with calcination temperature at 800 °C exhibited agglomerated particles of inhomogeneous size and were more evenly distributed. Variation of holding time in the manganese ores recovery process also affects the results of manganese recovery. The composition of the manganese recovery in the samples using holding time calcination variations of 3 and 4 hours was 83.88% and 89.24%, respectively. The results of the XRD analysis showed that the manganese phase formed using 3 hours of calcination holding time was dominated by Mn3O4 (hausmannite). Meanwhile, the manganese phase formed using 4 hours of holding time of calcination was dominated by Mn2O3 (bixbite).

Fabrication and mechanical properties of layered ceramic based on mullite platelets prepared via molten salt method

In this study, mullite platelets were successfully synthesized via molten salt method for fabrication of layered mullite ceramic. The effects of calcination temperature on the morphology and composition of the powder were investigated. With the temperature increase, the powder morphology transformed from irregular to flaky, ultimately resulting in the formation of mullite platelets with uniform particle size at 1000 °C. The growth mechanism of mullite platelets was discussed in details. Incorporating these mullite platelets as components in the fabrication of layered mullite ceramic resulted in high flexural strength and toughness (337.2 ± 24.3 MPa and 5.66 ± 1.3 MP m1/2). The layered structure improved the fracture toughness of mullite ceramic through mechanisms such as crack deflection, branching, mullite platelet rotation and bridging. The findings of this study would provide valuable insights and guidance for the fabrication of mullite ceramic with high strength and toughness.

Effect of Calcination Temperature on Surface Acidity and Photocatalytic Activity of Nano-TiO2/Diatomite Composite Photocatalyst

Nano-TiO2/diatomite composite photocatalysts were prepared by hydrolysis-deposition method in the present study. The effect of calcination temperature on surface acidity and photocatalytic activity of the photocatalysts was characterized by X-ray diffraction, N2 adsorption/desorption, Fransmission electron microscope, Fourier transform infrared, X-ray photoelectron spectroscopy, pyridine adsorption in situ fourier transform infrared and the adsorption and photodegradation of formaldehyde in air. Results revealed that the high temperature and the nucleation of titanium dioxide both can consume the surface Brönsted acid sites, and with the formation of Ti–O–Si bond to form surface Lewis acid. The composite calcined at 600 °C presents the highest decomposition of formaldehyde under UV irradiation at the room temperature.

Effect of Calcination Temperature on The Properties of Eggshell Waste (EW) Powder for Biomedical Application

Effect of Calcination Temperature on The Properties of Eggshell Waste (EW) Powder for Biomedical Application

Effects of Promoter and Calcination Temperatures on the Catalytic Performance of Y Promoted Co/WC-AC for Dry Reforming of Methane.

In this paper, the effects of promoter Y and calcination temperature on the catalytic activity and stability of Co/WC-AC catalysts were investigated. The results indicated that the introduction of Y decreased the reduction temperature of Co2O3 species and facilitated the formation of Co2+ species. Meanwhile, the addition of Y increased the content of lattice oxygen on the catalyst surface, which promoted the enrichment of chemistries oxygen on the catalyst surface and enhanced the carbon elimination capacity of the catalyst. The incorporation of metal Y facilitated the production of WC species in the catalysts, thus contributing to the stability of the catalysts. The activity and stability of the catalysts calcined at 550 ℃ were poor due to the presence of carbon materials with weak carbon interactions on the catalyst support surface. Meanwhile, the catalyst calcined at 700 ℃ lead to the instability of the carbon skeleton of the catalyst support due to the high calcination temperature, which caused the collapse of the pores and eventually led to the decrease of the catalyst stability. The Co-Y/WC-AC catalysts prepared at the calcination temperature of 600 ℃ had the best catalytic activity and stability.

Characteristics of Bioceramic Hydroxyapatite Based on Sand Lobster Shells (<i>Panulirus homarus</i>) as Sources of Calcium with Optimal Calcination Temperature

In this work, bioceramic hydroxyapatite (HAp) was synthesized based on sand lobster shells (Panulirs homarus) as a source of calcium using the precipitation method. Sand lobster shell powder was calcinated with temperature variations of 600, 800, and 1000 °C for 6 hours. The effect of calcination temperature on sand lobster shell powder was characterized to determine the optimal temperature for the synthesis of HAp. Based on the XRF (X-Ray Fluorescence) characterization, the highest calcium content (Ca) was 93% at a calcination temperature of 1000 oC. This result was supported by FTIR (Fourier Transform Infrared) spectrum that increasing the calcination temperature will reduce the intensity of carbonate ion (CO32-). These results showed that 1000 °C was the best calcination temperature on sand lobster shells to synthesize HAp. The characterization result of HAp using EDX (Energy Dispersive X-Ray) revealed that the molar ratio of Ca/P was 1.73. The FTIR and XRD (X-Ray Diffractometer) spectral pattern indicate that HAp had been successfully synthesized with minor-TCP, which is also a calcium phosphate with high biocompatibility.

Effect of calcination temperatures of kaolin on compressive and flexural strengths of metakaolin-concrete

The incorporation of pozzolanic materials in concrete construction is progressively increasing. This is due to technological advancement and climate change problems associated with carbon emissions resulting from the large-scale manufacturing of cement and its usage for concrete production. In this study, metakaolin obtained was used to partially substitute cement in metakaolin-concrete. Calcination temperatures of kaolin were varied from 500°C to 800°C at an interval of 100°C for 60 minutes. The metakaolin obtained was used to partially replace cement at 0, 5, 10, 15, 20 and 25 % by weight using a mix ratio of 1:2:4 and 0.4 water-cement ratio. Compressive strength test was carried out at curing ages of 7, 28 and 90 days, while the flexural strength test was performed at curing ages of 28 and 90 days. For both compressive and flexural strengths, 15 % by weight replacement with metakaolin gave the best strength values at all temperatures. An Increase in temperature led to a significant increase in the strength of metakaolin-concrete. ANOVA showed all factors significantly affected the flexural strength (P < 0.1), whilst the calcination temperature was significant (P < 0.1) to the compressive strength. This study showed that metakaolin is a supplementary cementitious material (SCM) and is a potential alternative to cement and can be used in the construction industry. Also, the calcination temperature of kaolin has a significant effect on the properties of the resulting metakaolin-concrete produced from it.

Oxygen-vacancy hydroxyapatite for visible-light photocatalytic degradation of tetracycline with online spectral monitoring

In this study, OV-HAp with abundant oxygen vacancies (OVs) were prepared by calcining carbonate-doped HAp (CHAp), and the effects of calcination temperature, time and atmosphere on the formation of OVs in OV-HAp and the influence of OVs concentration on its photoelectrochemical properties were investigated in detail. The results showed that the calcination temperature and atmosphere play a major role in the generation of OVs in OV-HAp. Through changing the temperature or atmosphere, the optical absorption range of OV-HAp can be broadened to the visible light and the band gap can be reduced to 1.6 eV. OV-HAp obtained by calcining CHAp at 600℃ for 5 h under H2 atmosphere (OV-HAp-H2) exhibited the highest efficiency for tetracycline (TC) photocatalytic degradation (65.4%). h+ and ·O2– were demonstrated to be the main active species in the degradation process by radical trapping experiments. Meanwhile, an integrated platform for photocatalytic degradation of TC with online spectral monitoring was constructed, and the feasibility of online spectral monitoring the TC degradation was tentatively explored. This work will provide a theoretical and technical basis for the development of HAp-based high-efficient photocatalysts, and this is favorable for promoting their use by a large scale for water pollutant removal. Moreover, it will also open a new path for online spectral monitoring and kinetic study of photocatalytic degradation of organic pollutants.

Effect of calcination temperature on one-step in situ preparation of SnSe/SnO2 heterojunction and its photocatalytic performance

This study aims to synthesize micro-nano SnSe/SnO2 heterojunction in situ in one step. The relationship between the temperature and structure, and the photocatalytic properties of the composite is explored. The structure, morphology, and optical properties of the catalyst are characterized. The photocatalytic activity of the developed composite is evaluated by testing the catalyst on methylene blue (MB) solution. The results reveal that the selenidation temperature considerably impacts the final structure of the developed materials. Sn3O4 is selenified at 700 °C, essentially forming a flower-like structure through self-assembly of nanoplates with a length and thickness of approximately 600 nm and 300 nm, respectively. The phase composition of selenide products at 700 °C is primarily SnSe and SnO2. SnSe/SnO2 heterojunction is formed simultaneously in situ, thus improving the charge transfer ability of the composite. Hence, SS-700 °C exhibits the best photocatalytic response in the tested materials. Additionally, the photocatalytic degradation of MB by SnSe/SnO2 heterojunction composites is highly dependent on the generation of hydroxyl radicals.

Optimization of mechanical performance of limestone calcined clay cement: Effects of calcination temperature of nanosized tubular halloysite, gypsum content, and water/binder ratio

Halloysite is a clay mineral that has a nanosized tubular morphology and high pozzolanic activity, and its calcination product can be used as a supplementary cementitious material in limestone calcined clay cement (LC3). In this study, the effects of the calcination temperature of halloysite, gypsum content, and water/binder (W/B) ratio on the mechanical properties and microstructures of LC3 were evaluated. The results demonstrated that halloysite calcined at the temperature of 650°C–850°C exhibited high pozzolanic activity: LC3 prepared using halloysite calcined above 650°C exhibited a shorter setting times and higher compressive strengths than those prepared with halloysite calcined at 550°C. This is attributable to the formation of more additional calcium aluminate silicate hydrate gel, and a larger amount of hemicarboaluminate and monocarboaluminate at higher temperatures than at lower temperatures, which results in more filling of pores in LC3 under the former conditions than the later conditions. The results also indicated that the optimum content of additional gypsum for LC3 was between 0 wt% and 2 wt%, and overdose gypsum did not substantially alter their setting times but decrease their compressive strengths. In contrast, a decrease in the W/B ratios decreased their setting times, total porosity, and increased their compressive strengths. Overall, in this study, LC3 prepared using halloysite calcined at 750°C, with a W/B ratio of 0.40 and without additional gypsum, exhibited the highest compressive strengths, which were 42.6, 51.7, and 57.1 MPa after 3, 7, and 28 days of curing, respectively. These findings deepen the research on the hydration mechanism of LC3 prepared with calcined halloysite and provide basic data for the wide application of this approach.

Selective Hydrogenation of Phenolic Compounds to Cyclohexanols over Nanosheet Ni@Al2O3 Catalysts

Herein, a series of nanosheet Ni@Al2O3 catalysts were prepared using the one-pot method, which offers good catalytic activity and selectivity of the phenolic compounds in aqueous due to their unique structures with rich active sites and large specific surface areas. The effects of calcination temperature, nickel loading, reaction temperature, and H2 pressure on the catalyst’s performance were studied on the simulated phenolic wastewater. The results indicated that phenolic compounds were selectively converted to the corresponding cyclohexanols regardless of the conversion by the 20%Ni@Al2O3-500 catalyst under mild conditions. Based on the procedure, cyclohexanol and water separation were simulated with the Aspen Plus model. This work provides an alternative scheme for treating phenolic wastewater.

A Promising Alternative for Aqueous Effluents Treatment: Modified Mesoporous Materials that are Photoactive under LED Visible Radiation.

AbstractTiO2 nanoparticles co‐doped with iron and carbon were tested in photocatalytic processes using visible radiation to degrade Acid Orange 7 and Paracetamol from aqueous solutions. In our previous reports, the mesoporosity and crystallinity of the samples were analyzed along with the calcination temperature effect. In this work, it was possible to verify the efficiency of a synergistic effect between dopants when a calcination at 150 °C was applied, favoring their localization in key sites of titania structure which improves the response under visible light. Such accomplishments could be also confirmed through photoluminescence analysis. Thus, the optimized solid showed an enhanced photocatalytic performance, reaching at only one hour of reaction, a complete degradation of both dye and drug while some intermediate species were reduced according to mineralization degree (around 80 %), and biodegradability achieved. Therefore, the proposed photocatalytic system presents potential as a previous step to a biological treatment for aqueous effluents.

Self-stabilisation of high-temperature calcined electrolytic manganese residue in mortar

High temperature calcination and mechanical ball milling are the most effective methods for increasing the volcanic ash activity of electrolytic manganese residues (EMR) and pretreating hazardous substances (NH3-N and Mn2+). In this study, the effects of different calcination temperatures (200, 400, 600, 800, and 1000 °C) and different EMR dosages (10, 15, and 20 %) on the mechanical properties, microscopic properties, and leaching toxicity of mortar were investigated. The results showed that the compressive strength of the prepared mortar mixture at different ages increased by 13.14 % to 24.5 % at a calcination temperature of 800 °C and dosage of 10 % EMR. Microscopic tests were performed to characterise the distribution of ettringite and calcium silicate hydrate gels on the surface of the mixed mortar. X-ray photoelectron spectroscopy and leaching toxicity analysis revealed the presence of EMR in the form of CaSiO3, MnO(OH)2, and M−NH4+. The leaching toxicity of Mn2+ and NH3-N in the EMR-blended mortar was significantly lower than the emission standards. The use of EMR in construction materials assists in resource utilisation and environmental protection.

Temperature effects on hard carbon derived from sawdust as anode materials for sodium ion batteries

BackgroundElectrochemical energy storage devices, namely batteries, are vital in reducing greenhouse gas secretions and are reliable alternatives to fossil fuel-based electrical energy storage systems. Thus, hard carbon (HC) is one of the most promising sustainable materials in the energy storage sector. MethodsThis study assembled sodium ion cells using sawdust powder resource-derived HC as an anode for sodium ion storage. We studied the effects of calcination temperature for the first time. Ball-milled and acid-washed sawdust powders were prepared by calcination at different temperatures. The characterization and electrochemical analyses of the HC synthesized at different temperatures were performed. Significant findingsWe found that the ratios of C = O and the micro/meso pore size distributions in HCs corresponded highly to the sodium ion storage performance. The half-cell, HC1200 (at 1200 °C) exhibited the highest reversible capacity of 320 mAh/g after 200 cycles at 0.5 A/g. The Na3V2(PO4)3(NVP)//HC1200 pouch-type full cells showed superior capacity retention of 96.7% and a coulombic efficiency of 98.9% after 400 cycles. The as-synthesized biomass carbon derived from sawdust powder is a potential anode material for sodium ion batteries.

5Y–ZrO2 NPs with high dispersity and excellent sintering performance prepared by a novel sol-gel-flux method in the NaCl system

Herein, to alleviate the hard agglomeration of ZrO2 nanoparticles (NPs) fabricated by the traditional sol-gel method (SGM), a novel sol-gel-flux method (SGFM) is applied to tailor ZrO2 nanoparticles (NPs) stabilized by 5 mol% Y2O3 (5Y–ZrO2) by in situ introduction of NaCl NPs among xerogel particles. The phase composition, micromorphology, surface area, and sintering performances of 5Y–ZrO2 products fabricated by SGM and SGFM are compared. The effects of calcination temperature on the phase composition, micromorphology, and particle size of 5Y–ZrO2 products prepared by SGFM are systematically investigated. The results show that the 5Y–ZrO2 particles prepared by SGM are severely agglomerated and irregular, while the 5Y–ZrO2 NPs prepared by SGFM are well dispersed, uniformly distributed, and quasispherical. The former can hardly be densified by sintering, while the latter shows excellent sintering performance. By sintering 5Y–ZrO2 NPs prepared by SGFM at 1200 °C for 3 h, 5Y-TZP with a high density and an average grain size of 0.29 μm is fabricated. The in situ generated NaCl particles effectively separate ZrO2 particles during sintering. The calcination temperature plays a crucial role in controlling the phase composition, agglomeration degree, micromorphology, particle size distribution, and particle size of 5Y–ZrO2 products synthesized by SGFM, and the optimal calcination temperature is suggested to be 790 °C.

Effects of Calcination Temperature Induced High-sensitivity N,N-dimethylformamide Gas-Sensing Performances Over LaFeO3 Nanoparticles

Recently, field effect transistor type N,N-dimethylformamide (DMF) sensors have been widely studied, but semiconductor resistance type DMF gas sensors have not been reported much. Herein, porous LaFeO3 nanoparticles were prepared by reverse co-precipitation, and the gas sensing detection performance of material was studied. The sensor based on LaFeO3 calcined at 750 °C shows excellent response (Rg/Ra = 189.2), great selectivity and long-term stability to 100 ppm DMF at the operating temperature of 170 °C. The effects of different calcination temperatures (650 °C, 750 °C, 900 °C) on the structure and properties of LaFeO3 were compared. The structural characterization data revealed that LaFeO3 calcined at 750 °C has the appropriate specific surface area and abundant active sites, which plays a key role in promoting the adsorption and decomposition of target gas. In addition, the surface of the LaFeO3 calcined at 750 °C has the highest concentration of adsorbed oxygen, which also provides an excellent condition for gas-sensitive reactions on the surface of the material. Therefore, LaFeO3 is expected to be a potential novel material in DMF detection.

Effect of Calcination Temperature on the Structure, Crystallinity, and Photocatalytic Activity of Core-Shell SiO2@TiO2 and Mesoporous Hollow TiO2 Composites

TiO2 and core–shell SiO2@TiO2 nanoparticles were synthesized by sol-gel process at different calcination temperatures. Mesoporous hollow TiO2 composites were prepared by etching SiO2 from SiO2@TiO2 nanoparticles with alkali solution. X-ray diffraction (XRD), Scanning electron microscope (SEM),Transmission electron microscope (TEM), and N2 adsorption–desorption isotherms, and Roman and Diffuse reflectance spectroscopy (DRS) were employed to characterize the synthesized materials. The effects of different calcination temperatures on the morphology, crystallinity, phase composition, and photocatalytic activity of the prepared materials were investigated in detail. It was found that the calcination temperature altered the phase structure, crystallinity, morphology, specific surface area, and porous structure. Additionally, it was verified that SiO2 could inhibit the transfer of TiO2 from anatase phase to rutile phase under high temperature calcination (850 °C). The hollow TiO2 calcined at 850 °C showed the highest photocatalytic efficiency of 97.5% for phenol degradation under UV irradiation.