Effect Of Calcination Temperature Research Articles

Biosynthesis of ZnO Nanoparticles Using Spirulina platensis Based on Calcination Temperature Changes and Its Antioxidant Activity

The effect of different calcination temperatures on molecular structure, morphology, and antioxidant activity was investigated for Zinc Oxide nanoparticles synthesized using the sol-gel method and the capping agent Spirulina platensis. The prepared nanoparticle ZnO was calcined at 160°C, 300°C, and 600°C according to the results of the DTA-TGA analysis. The effect of different calcination temperatures on the characterization of the prepared samples was studied using Fourier Transform Infrared (FTIR), X-ray Diffraction (XRD), and Field Emission-Scanning Electron Microscope (FE-SEM). In addition, the potential antioxidant activity of ZnO nanoparticles was investigated using the DPPH method. The results showed that FT-IR and XRD confirmed the presence of ZnO nanoparticles with good purity and small crystal size found in calcified ZnO nanoparticles at 600°C. FE-SEM confirmed the morphology ZnO nanoparticle produced at 600°C calcination are spherics, cubes, and nanorods with different particle sizes with range 50 – 150 nm. ZnO nanoparticles calcined at 600°C also showed higher antioxidant activity when compared to other calcination temperatures.

Effects of Calcination Temperature on Photocatalytic Activity of WO3 Materials for Tetracycline Degradation in Aqueous Environment under Visible Light

In the research, we successfully investigated effects of calcination temperature on the characteristics and photocatalytic activities of WO3 applying for degradation of antibiotics in aqueous environment under visible light. The crystal phases and optical properties of the synthesized WO3 nanoparticles were determined by an X-ray diffractometer (XRD), an UV-VIS diffuse reflectance spectroscopy (UV-VIS) and a photoluminescence spectroscopy (PL). The photocatalytic activities of the WO3 materials, which were calcinated at different temperatures, were studied via degradation of Tetracycline under visible light. Obtained results indicated that the orthorhombic phase was converted completely to monoclinic phase when the sample was calcinated at 500 oC. As compared to these WO3-300, WO3-400 and WO3-600 samples, the WO3-500 sample, which was calcinated at 500 oC, showed significant decrease in band gap energy and electron-hole recombination rate. Thus, the WO3-500 exhibited novel photocatalytic activity for Tetracycline degradation under visible light.

Highly reactive and anti-toxic cerium manganese oxides prepared by Ce-MOF two-step hydrothermal template method for complete catalytic oxidation of toluene

The MnCeOx catalysts were successfully prepared using a two-step hydrothermal method with Ce-MOF as a template for the complete catalytic oxidation of toluene. The effects of different Mn additions, calcination temperatures, and preparation methods on the material properties were investigated. In addition, the resistance of the catalysts to chlorosis was investigated. The results demonstrated that the 3%MnCeOx-300 showed the best catalytic activity with T90 only at 215 °C. Furthermore, after 2 h of 1, 2-dichloroethane toxicosis, the catalyst still converted >90% of the toluene, demonstrating good activity and anti-chlorine poisoning ability. Characterization results proved that the high activity and stability of the 3%MnCeOx-300 catalyst are attributed to the highest specific surface area and the highest Ce3+/Ce4+, Mn3+/Mn4+, and Olatt/O ratios.

Calcination temperatures influence the chemo-resistive gas sensing properties of biogenic zinc oxide nanoparticles with antibacterial activity

This study aimed to optimize Garcinia indica leaf extract mediated biogenic synthesis of antibacterial zinc oxide (ZnO) nanoparticles (NPs) and investigate how the calcination temperatures influence the structural and gas sensing properties of ZnO NPs. To study the effects of calcination temperatures, the optimally biosynthesized ZnO NPs were calcined at different temperatures in the range of 350-500 °C, used for the fabrication of thin films and characterized by various spectroscopic and imaging techniques. Characterization techniques confirmed that ZnO NPs were spherical with crystallite size in the range of 20-30 nm, mesoporous (with slit-shaped pores 1-10 nm), and had low band gap energy. Further, calcination temperatures were found to significantly influence the defect energy levels, porosity, surface roughness, and oxygen vacancies. In addition, the variation in calcination temperature was found to influence the gas response (Rg/Ra), relative response (%), sensitivity, response time, recovery time, and reproducibility. A higher gas response (231) was recorded for a thin film of ZnO NPs calcined at 400 °C than other tested temperatures. The average response and recovery time were 1 s and 218 s respectively for differently calcined ZnO NPs. ZnO NPs calcined at 400 °C were also found to exhibit remarkable antibacterial activity against E. coli and B. subtilis.

Effects of pH and calcination temperature on gel-combustion synthesizability of BaZr0.8Y0.2O3 perovskite

Solid oxide fuel cells with their advantages such as high efficiency are now considered as efficient power generation equipment. Because of its proton conductivity, perovskite is used in ceramic fuel cell electrolyte, and the addition of dopant can improve its proton conductivity. In this research, BaZr0.8-xSrxY0.2O3 (x=0, 0.05, 0.1, and 0.15) perovskites were synthesized by gel-combustion method. Barium nitrate, zirconium nitrate, yttrium nitrate and strontium nitrate were used as raw materials. Based on DTA and TGA analyses, the required temperature for calcination was determined to be around 1000 °C. XRD and FTIR analyses were used to identify the phases. The synthesis was carried out under different conditions and the effects of pH and dopant percentage on the morphology and size of the particles were investigated by FESEM. The sintering process was completed at different temperatures and a relative density of 94% was obtained at 1470 °C.

Biosynthesis of Au/CuO catalyst with Syringa oblata Lindl. leaf extract for efficient selective oxidation of glycerol to 1,3-dihydroxyacetone

Efficient conversion of glycerol to 1,3-dihydroxyacetone (DHA) is the affirmation and guarantee of the feasible development of biodiesel industry, but the biocompatibility of catalyst must be considered due to the wide application of DHA in food and medicine industries. In this work, an environmentally benign biosynthesis approach with Syringa oblata Lindl. (SoL) leaf extract was employed to fabricate Au/CuO catalysts for the oxidation of glycerol to DHA. The biosynthesized SoL-Au/CuO catalysts were characterized and the effects of plant extracts concentration, gold loading, calcination temperature and reaction conditions on the catalytic performance were systematically analyzed. High catalytic performance with glycerol conversion rate of 95.7% and DHA selectivity of 77.9% can be attained under optimum conditions. This work provides the first example of preparing biocompatible catalyst for the thermal catalytic oxidation of glycerol to DHA, which can not only reach efficient conversion of glycerol and selectivity to DHA, but also is simple, green, environmentally friendly, and promising.

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.