Optimization Of Calcination Conditions Research Articles

Effect of Calcination Temperature on the Physical Properties of Layered LiNiO<sub>2</sub> Prepared by Solid-State Reaction Method

A layered structure compound LiNiO2 material is synthesized by the solid-state reaction method under air atmosphere in the temperature range from 750 °C to 850 °C using Li2CO3 and NiO as the starting materials for 20 hours. The physical properties of the synthesized powder are investigated by X-ray diffraction (XRD), Field effect scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopic (FT-IR) techniques. The results of XRD patterns possessed the α-NaFeO2 structure of the rhombohedral system (space group, ) with no evidence of any impurities. The morphological features of the powders are characterized by field effect scanning electron microscopy (FESEM). The particles of LiNiO2 powder are generally in the form of a smoothly edged polyhedron and their average grain size is approximately 2 - 3 μm. The FT-IR spectroscopic data of LiNiO2 reveal the structure of the oxide lattice constituted by LiO6 and NiO6 octahedra. In general, from this study, we conclude that the LiNiO2 synthesized by solid state reaction method at different temperatures to increase in the sintering temperature. The lattice constant is increased, while the sintering temperature is increased. The maximum and minimum intensity ratios of XRD spectra shows that the optimum calcination condition is 800°C for 20 h. At 750-850°C, the particle size distribution is in the range of 2 - 3 μm.

Effect of Calcination Temperature on the Physical Properties of Layered LiNiO<sub>2</sub> Prepared by Solid-State Reaction Method

A layered structure compound LiNiO2 material is synthesized by the solid-state reaction method under air atmosphere in the temperature range from 750 °C to 850 °C using Li2CO3 and NiO as the starting materials for 20 hours. The physical properties of the synthesized powder are investigated by X-ray diffraction (XRD), Field effect scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopic (FT-IR) techniques. The results of XRD patterns possessed the α-NaFeO2 structure of the rhombohedral system (space group, ) with no evidence of any impurities. The morphological features of the powders are characterized by field effect scanning electron microscopy (FESEM). The particles of LiNiO2 powder are generally in the form of a smoothly edged polyhedron and their average grain size is approximately 2 - 3 μm. The FT-IR spectroscopic data of LiNiO2 reveal the structure of the oxide lattice constituted by LiO6 and NiO6 octahedra. In general, from this study, we conclude that the LiNiO2 synthesized by solid state reaction method at different temperatures to increase in the sintering temperature. The lattice constant is increased, while the sintering temperature is increased. The maximum and minimum intensity ratios of XRD spectra shows that the optimum calcination condition is 800°C for 20 h. At 750-850°C, the particle size distribution is in the range of 2 - 3 μm.

Co-catalyst free Titanate Nanorods for improved Hydrogen production under solar light irradiation

Harnessing solar energy for water splitting into hydrogen (H2) and oxygen (O2) gases in the presence of semiconductor catalyst is one of the most promising and cleaner methods of chemical fuel (H2) production. Herein, we report a simplified method for the preparation of photo-active titanate nanorods catalyst and explore the key role of calcination temperature and time period in improving catalytic properties. Both as-synthesized and calcined material showed rod-like shape and trititanate structure as evidenced from crystal structure and morphology analysis. Notably, calcination process affected both length and diameter of the nanorods into shorter and smaller size respectively. In turn, they significantly influenced the band gap reduction, resulting in visible light absorption at optimized calcination conditions. The calcined nanorods showed shift in optical absorption band edge towards longer wave length than pristine nanorods. The rate of hydrogen generation using different photocatalysts was measured by suspending trititanate nanorods (in the absence of co-catalyst) in glycerol-water mixture under solar light irradiation. Among the catalysts, nanorods calcined at 250∘C for 2 hours recorded high rate of H2 production and stability confirmed for five cycles. Photocatalytic properties and plausible pathway responsible for improved H2 production are discussed in detail.

Effect of Calcination Conditions on the Performance of Co-precipitation Catalyst

The Fe-Co-Ce composite catalysts were prepared by co-precipitation method, and the effect of calcination temperature and calcination time on the performances of the Fe-Co-Ce composite catalysts were investigated. The results indicated that the optimum calcination temperature and calcination time of the Fe-Co-Ce composite catalysts were 450 °C and 7 h, respectively. Using the catalysts which prepared under the optimum calcination conditions catalytic wet oxidation of methyl orange simulated wastewater, after 90 min, the COD, COD removal rate, absorbance, decolorization rate and pH of the methyl orange simulated wastewater were 737.7, 70.5%, 0.348, 95.3%, and 5.31, respectively. According to the analyses of the SEM, FTIR, and TG-DTA curves, the components of the catalysts which prepared under the optimum calcination conditions distributed evenly, and the chemical compositions of the catalysts including C-O, -OH, and H-O-H, showing a good thermal stability.

Dielectric Property of NaCu<sub>3</sub>Ti<sub>3</sub>NbO<sub>12</sub> Ceramics Doped with Small Amount MgO Nanopowder

In this study, the NaCu3Ti3NbO12 ceramics + (0-0.5 vol%)MgO nanopowder were prepared by solid state reaction. The precursors were ball milled for 24 hours and calcined at 700-1000°C. Selected the calcinations temperature with calculate pure phase from XRD results. The powders on selected temperature were various dwell time for 2-24 hours. The optimum calcination condition for NaCu3Ti3NbO12 powder is 950°C for 24 hours. The calcined powders were doped with small amounts of MgO nanopowder and pressed into a disc shape. Sinter the green body at 975-1025°C for 10 hours. Microstructure and density were examined by scanning electron microscope (SEM) and Archimedes method with distilled water as the fluid, respectively. The rectangular grain and normal grain growth are observed. The highest relative density of NaCu3Ti3NbO12 ceramics + (0-0.5 vol%)MgO nanopowder sintered at 1000°C are close to 90%. An impedance analyzer was also used to measure the dielectric constant (εr) of 1000°C sintered sample at room temperature. The doping of small amounts of MgO nanopowder to make improved NaCu3Ti3NbO12 ceramic dielectric constants and the optimum condition for doping MgO nanopowder is 0.1 vol%.

Preparation of rutile titanium dioxide pigment from low-grade titanium slag pretreated by the NaOH molten salt method

Low-grade titanium slag with a high accumulation of Mg, Al, Si, and the refractory structure of spinel, was sodiumized-oxidized to make it usable in the sulfate process for TiO2 pigment production. In the sodiumized-oxidized process, the Ti3O5 and Mg2SiO4 transform into Na2TiO3 and Na2MgSiO4, respectively. From combined ICP-OES with XRD refinement of the molten NaOH intermediate, the ideal stoichiometric ratio of NaOH to slag was calculated to be 0.9:1. After acidolysis of the intermediate, the obtained TiOSO4 solution, with Mg2+ and Al3+ impurities, was hydrolyzed to prepare metatitanic acid (H2TiO3) with a suitable particle size D(0.5) of 1.0–1.5 μm. The particle size D(0.5) of the hydrolyzed H2TiO3 decreased, while the concentration of Mg2+ and Al3+ increased. Finally, under optimal doping and calcination conditions, the rutile content of the prepared sample was 97.0%, and the achromic abilities of TCS and SCX were 1937 and 1.54, respectively.

Impact of Magnesium Oxide Preparation Conditions on Iodine Adsorption Capacity

Radioactive iodine gas is a problematic species in multiple nuclear energy–related applications. Therefore, it is highly desirable to develop an adsorbent that has a high capacity for iodine. In this investigation, the iodine adsorption capacity of high-purity magnesium oxide was investigated as a function of the calcination conditions. Differences in the magnesia substrates were characterized by scanning electron microscopy and X-ray diffraction, and the iodine adsorption capacity was determined using thermogravimetric analysis. The results indicate that the calcination temperature and time have a significant impact on the adsorption capacity, with longer times and higher temperatures having a negative impact. However, under the optimal calcination conditions identified in this study (550° for 20 min), the high-purity magnesia was found to have an adsorption capacity >300 mg of iodine per gram of sorbent. This suggests that magnesia holds promise for nuclear applications where iodine gas adsorption would be beneficial.

An ultrahigh-sensitivity and selective sensing material for ethanol: α-/γ-Fe2O3 mixed-phase mesoporous nanofibers

A process for synthesizing Fe2O3 based on electrospinning and the hard-template method was proposed such that the crystal phase of Fe2O3 could be tailored with precision. Mesoporous γ-Fe2O3, α-/γ-Fe2O3, and α-Fe2O3 nanofibers could be fabricated successfully by changing the synthesis parameters. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction analyses, Raman spectroscopy, and nitrogen adsorption–desorption analyses were used to characterize the structures of the synthesized products. The optimal calcination conditions for preparing α-/γ-Fe2O3 nanofibers with the highest ethanol response were determined through ethanol-sensing measurements. The mixed-phase material exhibited a significantly higher sensitivity than the corresponding purephase ones. The superior ethanol-sensing performance of the α-/γ-Fe2O3 nanofibers suggested that they may be suitable for use in alcohol sensing. Hence, a novel strategy for improving the sensing performance of metal oxide semiconductors is to assemble the different crystalline forms of the same metal oxide in one structure. Finally, the mechanism responsible for the sensing performance of α-/γ-Fe2O3 being higher than those of γ-Fe2O3 and α-Fe2O3 was elucidated on the basis of data from X-ray photoelectron spectroscopy and resistance measurements.

Preparation of U3O8 by calcination from ammonium uranyl carbonate in microwave fields: Process optimization

The effects of process conditions on preparation of U3O8 by calcination from ammonium uranyl carbonate in microwave fields were assessed and optimized for maximizing the total uranium as well as calcination temperature, adopting as Central Composite Design (CCD) methodology. The process variables assessed were calcination temperature, calcination duration and mass of sample. A quadratic model relating the process variables and the total amount of uranium and U3O8 was proposed eliminating the insignificant parameters. The optimal calcination conditions were estimated to be a calcination temperature of 942.75K, calcination duration of 8.78min, with the corresponding total uranium and U3O8 to be 82.07% and 31.33%, respectively.

OPTIMIZATION OF PURE BORAX PENTAHYDRATE EXTRACTION FROM CALCINED TINCAL

In this study, conditions for the calcination process of tincal were investigated and the optimum calcination conditions for boron extraction from tincal were determined. The experimental parameters were dissolution temperature, solid-to-liquid ratio, dissolution time and stirring speed. The optimum dissolution parameter levels were determined to be temperature 80 °C, solid-to-liquid ratio 10 g/dm 3 , stirring speed 250 rpm and dissolution time 5 min.

Photodegradation of phenol by N-Doped TiO2 anatase/rutile nanorods assembled microsphere under UV and visible light irradiation

N-doped TiO2 anatase/rutile nanorods assembled microspheres were successfully synthesized via a simple and direct sol–gel method containing titanium-n-butoxide Ti(OBu)4 as a precursor material, nitric acid as a catalyst, and isopropanol as a solvent. By manipulating calcination temperature, the photocatalyst consisting of different phase compositions of anatase and rutile was obtained. The prepared TiO2 nanoparticles were characterized by means of x-ray diffraction (XRD), field emission scanning microscope (FESEM), atomic force microscopy (AFM), Brunauer–Emmett–Teller (BET) analysis, UV–Vis–NIR spectroscopy, and fourier transform infrared (FTIR). The results from UV–Vis–NIR spectroscopy and FTIR revealed the direct incorporation of nitrogen in TiO2 lattice since visible absorption capability was observed at 400–600 nm. XPS study indicated the incorporation of nitrogen as dopant in TiO2 at binding energies of 396.8, 397.5, 398.7, 399.8, and 401 eV. Calcination temperature was observed to have a great influence on the photocatalytic activity of the TiO2 nanorods. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO2 nanoparticles was measured by photodegradation phenol in an aqueous solution under UV and visible irradiations. N-doped TiO2 anatase/rutile nanorods assembled microsphere (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400 °C exhibited the highest photocatalytic activity after irradiated under visible and UV light for 540 min. The high performance of photocatalyst materials could be obtained by adopting a judicious combination of anatase/rutile prepared at optimum calcination conditions.

Supercritical antisolvent precipitation of TiO2 with tailored anatase/rutile composition for applications in redox catalysis and photocatalysis

TiO2 with tailored anatase/rutile composition has been prepared from the supercritical antisolvent (SAS) precipitation of a range of titanium alkoxides. The calcination of the SAS TiO2 was monitored by in situ powder X-ray diffraction to determine the optimal calcination conditions for the formation of a mixed anatse/rutile phase TiO2. The SAS precipitated material calcined at 450°C produced a predominantly anatase support while calcination at 750°C resulted in a 90wt% anatase and 10wt% rutile TiO2. 5wt% AuPd was added to the SAS TiO2 using an impregnation technique, with exceptional dispersion of the metals being observed by transmission electron microscopy. Mean metal particle sizes were determined to be below 1nm for both anatase and anatase/rutile SAS TiO2 materials. These catalysts were found to be highly active for the selective oxidation of benzyl alcohol and the direct synthesis of hydrogen peroxide. In addition the anatase/rutile SAS TiO2 was found to have comparable activity to commercial anatase/rutile mixed phase TiO2 for the photocatalytic splitting of water for hydrogen production.

천연칼슘소재로서 개조개(Saxidomus purpuratus)와 바지락(Ruditapes philippinarum) 패각 및 소성분말의 특성

Shell waste from the butter clam Saxidomus purpuratus and littleneck clam Ruditapes philippinarum is a large by-product of shellfish aquaculture, and it is desirable to convert it into value-added products for industrial applications. In this study, calcium carbonate (CaC) polymorphs from butter clam (BCSP) and littleneck clam (LCSP) shell powders and commercial CaC were characterized using Fourier transmission infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results revealed that the optimal calcination conditions to eliminate organic substances and improve solubility for both BCSP and LCSP were <TEX>$800^{\circ}C$</TEX> for 8 h in an electrical furnace. Calcination improved the white index of the butter clam (BCCP) and littleneck clam (LCCP) calcined powder compared with shell powders. The calcium content in BCCP (51.1%) was higher than that of LCCP (44.9%) or commercial calcium oxide (CaO, 44.7%). The XRD patterns of BCCP and LCCP were similar to that of CaO. Cubic-like crystals of CaC and irregular crystals of BCCP and LCCP were observed by SEM. The FT-IR and XRD analyses revealed the presence of calcite and aragonite in the BCSP and aragonite in the LCSP, whereas the CaC contained calcite. These results indicate that butter and littleneck clam shells are potential biomass resources for calcium carbonate and calcium oxide.

Photocatalytic degradation of methylene blue dye over immobilized ZnO nanoparticles: Optimization of calcination conditions

In the present study, calcination conditions during the synthesis of zinc oxide nanoparticles were optimized using response surface methodology (RSM) based on central composite design (CCD). After that, the effect of the type of UV irradiation on the photocatalysis of methylene blue (MB) dye was studied based on the kinetic model obtained at optimum conditions. Analysis of variance (ANOVA) exhibited a reasonable high correlation coefficient between the predicted and experimental values (R 2 = 0.95). For a decolorization efficiency of 90%, the optimum calcination temperature and calcination time were identified to be 459 °C and 3.65 h, respectively. According to the reaction rate constant (k), the time required for the removal of MB using UVC lamps (0.027 1/min) was shorter than that of UVA lamps (0.0098 1/min), indicating higher exciting potential of the UVC irradiation for the generation of hydroxyl radicals through photocatalysis.

Facile preparation of NiCo2O4 nanobelt/graphene composite for electrochemical capacitor application

A hybrid composite containing ultrathin NiCo2O4 nanobelts and graphene nanosheets was prepared through a simple and scalable hydrothermal method combined with suitable heat treatment. The optimal calcination condition has been optimized by investigating the pseudocapacitive behaviour of bare spinel NiCo2O4 prepared at different calcination temperatures. It is found that the self-assembled microstructure of NiCo2O4 nanobelts prepared at 250°C (named as S250) exhibit superior electrochemical performance to those prepared at other temperatures. The composite comprising NiCo2O4 nanobelts and graphene nanosheets (GS250) has enlarged specific surface area (222m2/g), yielding a high specific capacitance of 1072.91F/g at the current density of 1A/g with desirable rate performance and cycling stability. In view of simple, high-yield synthetic route and remarkable electrochemical properties, this NiCo2O4 nanobelt/graphene hybrid composite should be a promising electrode material for supercapacitors in high energy density storage systems.

회분식 반응기에서 TiO&lt;sub&gt;2&lt;/sub&gt; 광촉매의 MEK 분해특성-금속담지영향

In photocatalytic reaction, the doping of metal matter can alter the titania surface properties. As such the metal matter can increase the rate of the reaction. The influence of metal doping and calcination condition of TiO2 photocatalyst was investigated at the batch-type photoreactor. Several metal matters were doped to the TiO2 catalyst to improve photodegradation efficiency. During the experiments, water content was 3wt%, and reactor temperature was 40℃. Palladium-doped TiO2 was found to be the best, where as platinum or tungsten-added also showed good results. Additional doping of platinum or tungsten on Pd/TiO2 had no increase on the removal efficiency. To obtain proper calcination condition, various experiments about calcination temperature and time were carried out. As a result, the optimum calcination condition was temperature of 400℃, time of 1 hour.

Effects of La3+–Nd3+ ions and pre-calcination on the growth of hexaferrite nanoparticles prepared by gel to crystallization technique: Non-isothermal crystallization kinetics analysis

This is the first report ever on La3+–Nd3+ doped M-type hexaferrite nanoparticles: SrNdxLayFe12−x−yO19 (0 ≤ x ≤ 1) prepared by citrate precursor using the sol–gel technique followed by gel to crystallization. The substitution effects of ions and molar ratio of Fe3+/Sr2+ on the formation of ferrite phase were examined using powder differential thermal analysis (DTA) technique, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (Mid-IR) and vibrating sample magnetometer (VSM). The present work aim to study the crystallization of binary La3+- Nd3+ doped hexaferrite nanoparticles. DTA technique was employed to investigate the formation of nanocrystalline SrNd0.4La0.4Fe11.2O19 and revealed that the formation of ferrite phase was occurred in steps and crystallization take place by the means of endothermic reactions. The value of activation energy and crystallization temperature has been obtained from DTA data using different non-isothermal methods. XRD and Mid-IR studies have confirmed the formation of ferrite phase. Through this work an optimum calcination condition was established for the synthesis of single phase hexaferrite nanoparticles even after the substitution of binary rare earth elements. Magnetic properties were determined by using a vibrating sample magnetometer. The magnetic results revealed that the synthesized nanoparticles are suitable for perpendicular recording media due to their high coercivity value.

Iron leaching from bauxite ore in hydrochloric acid using response surface methodology

In this work, hydrochloric acid is used to remove iron impurities in the bauxite ore contained in the diasporite mineral located in the Sari region. The bauxite ore was calcined at different temperatures and times, and then dissolved in a hydrochloric acid solution. After determining the optimum calcination conditions in 1 h at 900 °C, the response surface methodology (RSM) with four factors in five levels was employed in order to evaluate the effects of calcination temperature, calcination time, acid concentration, and leaching time on the iron leaching efficiency. A quadratic model is proposed using this methodology to correlate the leaching variables. The test results indicate that the model is consistent with the experimental data, and that the most important varriables involved are the acid concentration, leaching time, and squared term of calcination temperature (A2). The maximum iron recovery was 94.97%, and the Fe grade in the solids remained was 2.35% at the calcination temperature of 900 °C, a calcination time of 1 hour, and a leaching time of 2 h in hydrochloric acid (6 mM).

Photocatalytic Improvement under Visible Light in TiO2 Nanoparticles by Carbon Nanotube Incorporation

Photocatalytic activity of TiO2 nanoparticles was successfully enhanced by addition of multiwall carbon nanotubes (MWCNT) to make CNT/TiO2 nanocomposites by sol‐gel method at ambient temperature. CNT treated by HNO3 : H2SO4 treatment (1 : 3 v/v) was mixed with TiO2 nanoparticles at various molar ratios and calcination temperatures. The optimal molar ratio of CNT : TiO2 was found at 0.05 : 1 by weight. The optimal calcination condition was 400°C for 3 h. From the results, the photocatalytic activities of CNT/TiO2 nanocomposites were determined by the decolorization of 1 × 10−5 M methylene blue (MB) under visible light. CNT/TiO2 nanocomposites could enhance the photocatalytic activity and showed faster for the degradation of MB with only 90 min. The degradation efficiency of the MB solution with CNT/TiO2 nanocomposite achieved 70% which was higher than that with pristine TiO2 (22%). This could be explained that CNT prevents TiO2 from its agglomeration which could further enhance electron transfer in the composites. In addition, CNT/TiO2 nanocomposites had high specific surface area (202 m2/g) which is very promising for utilization as a photocatalyst for environmental applications.

Preparation and Photocatalytic Activity of Mixed Phase Anatase/rutile TiO2 Nanoparticles for Phenol Degradation

The evolution of desirable physico-chemical properties in high performance photocatalyst materials involves steps that must be carefully designed, controlled, and optimized. This study investigated the role of key parameter in the preparation and photocatalytic activity analysis of the mixed phase of anatase/rutile TiO2 nanoparticles, prepared via sol-gel method containing titanium-n-butoxide Ti(OBu)4 as a precursor material, nitric acid as catalyst, and isopropanol as solvent. The prepared TiO2 nanoparticles were characterized by means of XRD, SEM, and BET analyses, and UV-Vis-NIR spectroscopy. The results indicated that the calcination temperature play an important role in the physico-chemical properties and photocatalytic activity of the resulting TiO2 nanoparticles. Different calcination temperatures would result in different composition of anatase and rutile. The photocatalytic activity of the prepared mixed phase of anatase/rutile TiO2 nanoparticles was measured by photodegradation of 50 ppm phenol in an aqueous solution. The commercial anatase from Sigma-Aldrich and Degussa P25 were used for comparison purpose. The mixed phase of anatase/rutile TiO2 nanoparticles (consists of 38.3% anatase and 61.7% rutile) that was prepared at 400°C exhibited the highest photocatalytic activity of 84.88% degradation of phenol. The result was comparable with photocatalytic activity demonstrated by Degussa P25 by 1.54% difference in phenol degradation. The results also suggested that the mixed phase of anatase/rutile TiO2 nanoparticles is a promising candidate for the phenol degradation process. The high performance of photocatalyst materials may be obtained by adopting a judicious combination of anatase/rutile and optimized calcination conditions.