Increasing Calcination Temperature Research Articles

Synthesis of ferromagnetic material nano powder and study of its effect on antibacterial activity

This work is to synthesize the cobalt ferrites nano powder of with the stoichiometric formula CoxFe2O4 (x= 0.8 and 1.4) by using sol-gel auto combustion method , and study structural and magnetic properties, the ferrite powders were calcined at 500, 600, and 700 °C for 3 hrs to remove organic waste and increase homogeneity and, The XRD diffraction analysis for CoxFe2O4 nanoferrites with single spinel structure. The crystal size of the formed crystallite of ferrite specimens increases with increasing temperature calcination and cobalt content , (FE-SEM) shows agglomerated with homogenous spherical and polyhedral particles. proportion of each of Fe ,Co, and O in all specimens is confirmed using the Energy Dispersive Spectrum (EDS),the magnetic characteristics are measured with a VSM. The remanence magnetization (Mr) saturation magnetization(Ms), and magnetic moment (nB) of CoxFe2O4 nanoferrites are found to go up with increasing calcination temperature, and E-coli bacteria were used to examine the inhibition of each ferrite using the diffusion-drilling agar method, as it is known that these nano powder possess therapeutic efficacy for numerous diseases.

Optimizing the synthesis process for Lithium-Ion sieve adsorbents: Effect of calcination temperature and heating rate on reaction efficiency and performance

Processing-structure–property relationships play a crucial role in tuning the performance of materials for a given application in order to attain a suitable set of optimal conditions, and it is therefore imperative to evaluate the parameters of either the synthesis, delithiation, adsorption, and desorption process. Through an orthogonal test design of the solid-state synthesis process, it was determined that a heating rate of 1 ℃/min had consistently higher reaction efficiencies of 68.1 %, 68.6 %, and 72.3 % at the calcination temperatures of 650 ℃, 700 ℃, and 750 ℃ respectively compared to heating rates of 4 ℃/min and 7 ℃/min. Moreover, a decrease in delithiation efficiency with increase in calcination temperature (99 % at 650 ℃, 96.1 % at 700 ℃, and 94.2 % at 750 ℃) at the 1 ℃/min heating rate was observed which was attributed to an increase in the average crystallite size. Adsorption performance of the synthesis-optimized zinc-doped lithium metatitanate showed consistently high adsorption efficiency (>90 %) despite the low adsorption capacity (4.9 mg/g) which was attributed to the low initial lithium-ion concentration of the lithium chloride solution and high adsorbent dosage.

Nanofibrous perovskite ceramics with in-situ exsolved Ni3Fe alloy nanoparticles for catalytic CO2 methanation

Exsolution is a promising method to prepare highly-dispersed and stable nanocatalysts, while exsolution efficiency is limited by the high temperature crystallization of parent perovskite ceramics, which leads to the low surface area of parent oxides for exsolution. The fibrous structure of ceramics shows highly-thermal stability, and this study employed the thermally-stable structure to realize the high efficiency of exsolved nanocatalysts from perovskites. Sr0.95Ti0.3Fe0.55Ni0.15O3-δ nanofibrous perovskites catalysts were prepared by electrospinning and subsequent calcination and reduction. The amount of exsolved Ni3Fe alloy nanoparticles increased with calcination temperature up to 1075 °C while the catalysts retained the nanofibrous structure. Further increasing calcination temperature to 1100 °C caused catalyst agglomeration. The Ni dissolution was also optimized by tuning the amount of Ni-doping to maximize catalyst activity. The nanofibrous catalysts demonstrated high and stable performance in CO2 methanation, and achieved the CO2 conversion and CH4 selectivity of 70.5% and 94.4% at 450 °C. Therefore, the merits of exsolution method have been realized over the nanofibrous perovskite catalysts.

The Role of Calcination Temperature in the Self-cleaning Functionality of Urea-Doped TiO2 Prepared through In Situ Heat-Assisted Sol–Gel Synthesis

In this study, urea-doped titanium dioxide (urea-TiO2) nanoparticles were synthesized through an in situ heat-assisted sol–gel technique using titanium (IV) isopropoxide as the precursor for titanium dioxide and urea as a nitrogen source. The nanoparticles were calcined at 300, 500, and 700 °C to study the effect of the calcination temperature on their function as self-cleaning material. The nanoparticles were characterized using a scanning electron microscope and a transmission electron microscope for morphology, X-ray diffraction, Raman spectroscopy, and Fourier transformed infrared spectroscopy for structure, UV–Vis, and photoluminescence spectroscopy for optical analysis. The self-cleaning study was carried out by letting samples degrade methylene blue and Rhodamine-B under UV irradiation. The morphological analysis reveals particle size distribution with more disparity at higher calcination temperatures. At lower calcination temperatures, the dopant caused high clustering of particles, keeping them linked together in muddy form and layers. Structural analysis showed that the particles were nanostructured with average crystallite sizes ranging from 2.35 to 16.13 nm and phase transformation from anatase to rutile after calcining at 700 °C. The nitrogen presence created a lattice disorder in the TiO2 structure, and the impact of higher calcination temperature on the nanoparticles further shifted the band toward a higher wavenumber under FTIR analysis. The optical bandgap reduced from 3.29 eV at 300 °C to 3.09 eV at 700 °C. The determined values of the rate constant from the photodegradation test showed that the highest rate was obtained at 700 °C, indicating enhanced self-cleaning functionality with an increase in calcination temperature of urea-TiO2.

Electrocatalytic and photocatalytic activities of hierarchically structured zinc oxide nanoparticles derived from cellulose paper-precipitated hydrozincite

This study presents a novel method for synthesizing hierarchical porous zinc oxide (ZnO) nanostructures by thermally decomposing green-synthesized hydrozincite. The hydrozincite was prepared at room temperature using zinc acetate dihydrate and calcium carbonate (CaCO3) in cellulose printing papers as the precipitating agent. The resulting ZnO particles exhibit a distinctive flower-like morphology, consisting of porous nanosheets composed of interconnected nanoparticles. The average crystallite size of the hierarchically structured zinc oxide nanoparticles, as determined via X-ray diffraction Rietveld refinement method, was found to be 18.8 nm when calcined at 500 °C. However, with increasing calcination temperature to 600, 700, and 800 °C, the average crystallite size also increased to 24.3, 30.4, and 47.2 nm, respectively. The ZnO synthesized at temperatures of 500 °C, 600 °C, and 700 °C exhibits higher electrocatalytic activity toward the hydrogen evolution reaction (HER) compared to both the ZnO synthesized at 800 °C and commercial ZnO. This enhanced performance can be primarily attributed to the nanosized ZnO particles, which provide a substantial surface area, high accessibility of active sites, and fast charge transfer kinetics. In terms of photocatalytic activity, all the samples show HER improvement under the UV light irradiation, attributed to the generation of photoexcited charge carriers. The ZnO synthesized at 800 °C and the commercial ZnO exhibit greater enhancements in photocatalytic activity compared to the other samples. This implies that larger solid particles with fewer nanopores result in a greater exposed surface area for UV-light absorption. The hierarchically structured ZnO nanoparticles demonstrate promising electrocatalytic and photocatalytic activities, as well as stability, opening up potential applications in various fields, including energy conversion and environmental remediation.

Bi2O3 nanoparticles: phytogenic synthesis, effect of calcination on physico-chemical characteristics and photocatalytic activity

ABSTRACT The present work reported the bioinspired synthesis of Bi2O3 nanoparticles (NPs) using Ziziphus mauritiana leaves aqueous extract at four annealing temperatures (300, 400, 500, and 600C°) and examined annealing temperatures effect of on various physicochemical characteristics and photocatalytic activities of NPs. The XRD and Raman results reveal the existence of α and β polymorphs of Bi2O3 in all samples but with increase of calcination temperature the extent of α-phase, particle size, and crystallinity were increased while band gap value decreased. The BET results confirmed the mesoporous structure of all samples. Further, decolorization experiments conducted with crystal violet (CV) dye showed an observable effect of annealing temperature on the adsorption and photocatalytic efficacy of the prepared samples, and the utmost (99.88 %) removal of CV dye was computed with the Bi2O3 nanoparticles calcined at 300oC (B-300). The main active species involved in the photo-mineralization of dye was h+ followed by •OH..

Effect of calcination process on ferrite phase and silicate phase of ferrite-belite-rich Portland cement clinker from industrial solid waste

In this paper, the industrial solid waste with potential cementitious activity was used to prepare ferrite-belite-rich Portland cement clinker. The changes in solid waste composition, raw meal ratio, calcination temperature, and holding time on the type and content of iron aluminate phase and silicate phase in the clinker were studied. The effects of flue gas desulfurization gypsum on the mechanical properties of clinker, mineral composition, and microstructure of hardened slurry were briefly discussed. In addition, the sustainability of the production of ferrite-belite-rich Portland cement clinker was evaluated by using a life cycle assessment. The analysis results show that: (1) The content of the ferrite phase increased first and then decreased with the increase of calcination temperature, and the content of the silicate phase and ferrite phase increased first and then decreased with the extension of holding time. (2) With the change of calcination temperature, the silicate phase is always cobblestone-like and evenly distributed. The ferrite phase changes from granular or flake to branch dendritic, and finally is swallowed by the liquid phase, filled between the gaps of the silicate phase structure, or attached to the surface of the silicate phase. (3) The Si elements in the clinker are always agglomerated in cobblestone shapes with uneven sizes. With the holding time from 30 min to 60 min, the distribution area of Al and Fe elements in the gaps of silicate phases increased gradually. Some Al and Fe elements are distributed in the area where silicate phase minerals are located. When the holding time is extended to 90 min, Fe and Al elements tend to be randomly distributed. (4) Fe will replace part of Al to form Fe-ettringite, Fe-siliceous hydrogarnet, etc. in the hydration process of C4AF. (5) The use of red mud, carbide slag, and silica fume to produce ferrite-belite-rich Portland cement clinker will reduce carbon emissions by 57.50%.

Evaluation of calcined coal slime in binary and ternary ordinary portland cement composites: The role of calcination temperature

Coal slime is a by-product of coal washing plants, which accounts for around 8.3% of total coal production. China generates about 200 million tons of coal slime annually, and most of which can not be utilized efficiently. As a result, the disposal of coal slime leads to serious environmental problems and high costs. To provide a green utilization of coal slime, this study investigated the preparation of binary and ternary cement binder systems by using various calcined coal slime particles. The effects of calcination temperatures (600 °C, 700 °C, 800 °C, and 900 °C) on the evolution of mineral phases, microstructure and morphology of coal slime were addressed and discussed. The feasibility of calcined coal slime in blended cement preparation was tested and evaluated in comparison with calcined coal gangue. The results indicated that kaolinite in coal slime can be effectively transformed into metakaolin at 600 °C. The increase of calcination temperature after 600 °C reduced the reactivity, porosity and water demand of calcined coal slime. 600 °C Calcined coal slime effectively promoted the formation of monosulfate and the monocarboaluminate in binary and ternary cement, respectively, as well as the hydration process. The highest compressive strength of the calcined coal slime blended sample achieved 48.04 MPa, which presented a higher performance than the calcined coal gangue. The organic components in coal slime could be the key to reaching a high reactivity at a low (600 °C) calcination temperature. The calcined coal slime has the potential to be a reactive additive in cement-based materials.

Size-Controlled Synthesis of IrO2 nanoparticles at High Temperatures for the Oxygen Evolution Reaction

Polymer electrolyte membrane (PEM) electrolysis is considered to play a vital role in the sustainable energy transition. The efficient generation of hydrogen is largely influenced by the slow rate of the anodic oxygen evolution reaction (OER). Iridium oxide represents one of the most promising catalysts for the electrochemical oxidation of water in an acidic environment. Under harsh operating conditions at the anode, iridium oxide is found to be among the most dissolution-resistant catalysts while offering acceptable OER activity. However, iridium’s limited availability dictates high costs centralizing the research in direction of reducing noble metal content while maintaining favorable electrochemical properties.[1] Designing nanostructured catalyst with an increased surface-to-volume ratio improves the application-oriented mass-specific activity.[2] Hydrous iridium oxide is known for superior OER activity, but for a successful application, drastic dissolution of the catalyst must be addressed by stabilization. This can be achieved by heat treatment to temperatures ≥400ºC with the formation of crystalline order. However, managing to avoid agglomeration of nanoparticles at high temperatures is not trivial, thus, temperature studies on electrochemical stability and activity on similar particle sizes are missing.[3]. Here, we demonstrate how nanoparticles below 10 nm can be obtained at high preparation temperatures up to 800 °C with unprecedented control over particle size and morphology. A detailed understanding of the structural evolution during heating was obtained by in-situ scanning transmission electron microscopy (in-situ STEM) with locally resolved nanoparticles, high spatial resolution, and chemical specificity. Additionally, changes in surface properties at different temperatures were tracked ex-situ by X-ray photoelectron spectroscopy (XPS), the crystal structure was investigated by X-ray diffraction analysis (XRD), size and morphology were characterized by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The OER activities of synthesized iridium oxide nanoparticles were measured in half-cell measurements at forced convection. The stability was carefully studied by operando flow cell measurements that were coupled to online inductively coupled plasma mass spectrometry.[4] The iridium oxide catalyst calcined at the lowest temperature resulted in outstanding mass-specific activity outperforming the reference iridium oxide catalyst by a factor of 40. By gradual increase in calcination temperatures up to 800 °C, we observe improvement in the durability of the synthesized catalysts, being comparable to the reference catalyst, yet still with notable improvement in catalytic activity. This is the first report to synthesize iridium oxide nanoparticles at high temperatures with preserved size and morphology not exceeding 10 nm and allows for the determination of activity and durability of similarly sized nanostructures.[5] Literature:[1] M. Bernt et al. Chemie Ingenieur Technik 2020, 92, 31-39.[2] T. Reier, et al. ACS Catalysis 2012, 2, 1765-1772.[3] Y. Lee et al. The Journal of Physical Chemistry Letters 2012, 3, 399-404.[4] S. Geiger et al. Nature Catalysis 2018, 1, 508-515.[5] M.Malinovic et al. Advanced Energy Materials 2022, Manuscript submitted for publication.

New insights on the effects of surface facets and calcination temperature on electrochemical properties of MnCo2O4 as bifunctional oxygen electrocatalyst in zinc-air batteries

Metal-air rechargeable batteries are being studied as an alternative to lithium-ion batteries. MnCo2O4 as a ternary mixed metal oxide appeared as a promising oxygen electrocatalyst in metal-air batteries due to relatively high electrocatalytic activity and electronic conductivity. The effects of surface facets and calcination temperature on the electrochemical properties of MnCo2O4 in zinc-air batteries are investigated experimentally and theoretically. The results show that by increasing calcination temperature, the surface facet is changing from the high index {112} to the low index {110}. Concurrently, the oxygen vacancy concentration rises with calcination temperature. Electrochemical results and first principle calculations indicate that the oxygen-deficient {110} facet has superior electrochemical activity over the {112} facet in terms of oxygen evolution reaction and oxygen reduction reaction. These results are essential for designing high performance spinel structured electrocatalyst materials.

Surface Lattice-Embedded Pt Single-Atom Catalyst on Ceria-Zirconia with Superior Catalytic Performance for Propane Oxidation.

Tuning the metal-support interaction and coordination environment of single-atom catalysts can help achieve satisfactory catalytic performance for targeted reactions. Herein, via the facile control of calcination temperatures for Pt catalysts on pre-stabilized Ce0.9Zr0.1O2 (CZO) support, Pt single atoms (Pt1) with different strengths of Pt-CeO2 interaction and coordination environment were successfully constructed. With the increase in calcination temperature from 350 to 750 °C, a stronger Pt-CeO2 interaction and higher Pt-O-Ce coordination number were achieved due to the reaction between PtOx and surface Ce3+ species as well as the migration of Pt1 into the surface lattice of CZO. The Pt/CZO catalyst calcined at 750 °C (Pt/CZO-750) exhibited a surprisingly higher C3H8 oxidation activity than that calcined at 550 °C (Pt/CZO-550). Through systematic characterizations and reaction mechanism study, it was revealed that the higher concentration of surface Ce3+ species/oxygen vacancies and the stronger Pt-CeO2 interaction on Pt/CZO-750 could better facilitate the activation of oxygen to oxidize C3H8 into reactive carbonate/carboxyl species and further promote the transformation of these intermediates into gaseous CO2. The Pt/CZO-750 catalyst can be a potential candidate for the catalytic removal of hydrocarbons from vehicle exhaust.

Cobalt cross-linked ordered mesoporous carbon as peroxymonosulfate activator for sulfamethoxazole degradation

Ordered mesoporous carbons (OMCs) functionalized with catalytically-active metals have many potential applications in sulfate radical-based advanced oxidation processes for degrading antibiotics. Cobalt cross-linked ordered mesoporous carbon materials (OMC-Co-Tx) were synthesized through evaporation-induced self-assembly, calcinated at (600 to 800) oC. The OMC-Co-Tx materials were then employed as peroxymonosulfate (PMS) activators for removal of sulfamethoxazole (SMX) from aqueous solutions. OMC-Co-T800 prepared by calcination at 800 °C had a large specific surface area (449 m2/g), uniform pore structure (∼4.5 nm) and showed the best performance for activation of PMS. With a dosage of 0.1 g/L OMC-Co-T800 and 0.4 g/L PMS, the functionalized OMC material allowed SMX (10 mg/L) removal of up to 99% in 30 min. The increase of calcination temperature promoted the reduction of cobalt in OMC materials and increased the defects in their structure, resulting in better catalyst behavior. Quenching experiments and electron paramagnetic resonance analyses showed that reactive species of sulfamethoxazole degradation involved in the OMC-T800/PMS system were SO4•−, OH, O2•− and 1O2. HPLC-MS analyses of degradation intermediates formed in the OMC-Co-T800/PMS system allowed elucidation of four transformation pathways for SMX degradation.

Magnesium-Rich Calcium Phosphate Derived from Tilapia Bone Has Superior Osteogenic Potential.

We extracted magnesium-rich calcium phosphate bioceramics from tilapia bone using a gradient thermal treatment approach and investigated their chemical and physicochemical properties. X-ray diffraction showed that tilapia fish bone-derived hydroxyapatite (FHA) was generated through the first stage of thermal processing at 600-800 °C. Using FHA as a precursor, fish bone biphasic calcium phosphate (FBCP) was produced after the second stage of thermal processing at 900-1200 °C. The beta-tricalcium phosphate content in the FBCP increased with an increasing calcination temperature. The fact that the lattice spacing of the FHA and FBCP was smaller than that of commercial hydroxyapatite (CHA) suggests that Mg-substituted calcium phosphate was produced via the gradient thermal treatment. Both the FHA and FBCP contained considerable quantities of magnesium, with the FHA having a higher concentration. In addition, the FHA and FBCP, particularly the FBCP, degraded faster than the CHA. After one day of degradation, both the FHA and FBCP released Mg2+, with cumulative amounts of 4.38 mg/L and 0.58 mg/L, respectively. Furthermore, the FHA and FBCP demonstrated superior bone-like apatite formation; they are non-toxic and exhibit better osteoconductive activity than the CHA. In light of our findings, bioceramics originating from tilapia bone appear to be promising in biomedical applications such as fabricating tissue engineering scaffolds.

Effects of Calcination Temperature and Calcination Atmosphere on the Performance of Co3O4 Catalysts for the Catalytic Oxidation of Toluene

A series of Co3O4 catalysts were synthesized and derived from Co-BTC (BTC = 1,3,5-benzenetricarboxylic acid). The effects of different calcination temperatures and calcination atmospheres on the catalytic activity of the materials were investigated. The characteristics of the catalysts were investigated by using various techniques, including X-ray diffraction, N2 adsorption–desorption measurements, scanning electron microscopy, X-ray photoelectron spectroscopy, and H2 temperature-programmed reduction. The findings demonstrated that an increase in calcination temperature caused a higher agglomeration of grains, reduced the specific surface area, and influenced the contents of the active substance Co3+ and surface-adsorbed oxygen of the catalyst. The catalyst pretreated under the N2 atmosphere showed a more uniform particle distribution, better low-temperature reducibility, and the highest catalytic activity. The in situ DRIFTS results indicated that toluene was decomposed successively to benzaldehyde, benzoic acid, bicarbonate, and carbonate species and was eventually broken down into small molecules of CO2 and H2O as the temperature increased.

Role of the thermal regime in the defect formation of zinc oxide nanostructures prepared by the thermal decomposition process

Abstract The intrinsic defect of ZnO depicts a crucial role in the charge transfer owing to the suppression of the exciton recombination, exhibiting superior semiconducting performance. In this study, the intrinsic defect of ZnO nanostructures prepared by direct thermal activation of 300–900 °C was investigated. X-ray diffraction (XRD) was employed to analyze phase, crystallite size, Zn–O bond length, and dislocation density. The relation of Williamson–Hall (W–H) was used to calculate crystallite size and micro-strain. The atomic coordination was approximated through the Rietveld method. Morphology and crystal growth investigation was carried on by scanning electron microscope (SEM) and tunneling electron microscope (TEM), exhibiting rod-like nanostructures transform to oval shape particle with high residual strain when increasing calcination temperature, exhibiting the crystal growth direction of (101). Specific surface and pore analysis reveals a significant value corresponding to SEM analysis. Fourier transform infrared spectroscopy (FT-IR) detected Zn–O stretching vibration bands, presenting a notable increase in the intensity when heat at 600 °C. Relating to the thermal regime, energy bandgap (Eg) was found to be 3.41–3.50 eV as increasing heat treatment temperatures. Photoluminescence (PL) was applied to determine intrinsic defects through emissive spectra. The surface charge was determined through the zeta potential measurement. The photo-induced dye degradation was measured to understand the effect of the defect in semiconductors. The X-ray photoelectron spectroscopy (XPS) confirms the wurtzite structure appearance, including the intrinsic defects. The observed intrinsic defects are discussed, associating with the structural constants, emissive spectra, cationic dye degradation, and binding energy.

Study on the loaded morphology of active metal components in Cu-M@ carbon-based catalysts and their protection against SO2

In this paper, the samples of metal impregnators for activated carbon were prepared by Cu compound with Co, Ni, Zn and Mo compounds, respectively. The loading forms of metal compounds on activated carbon were investigated. With the increase of calcination temperature, the crystal form of the activated carbon metal impregnant sample changes correspondingly. Under the calcination temperature of 200 °C, the sample of copper impregnator completely decomposes into copper oxide with a monoclinic crystal phase structure, and the cobalt impregnator samples decompose from CoCO3 to Co3O4. Its main component is Co3O4, with a cubic phase structure. The metallic zinc compounds decomposed completely into hexagonal zinc oxide crystals with a wurtzite structure. For the solid sample of molybdenum impregnation agent, ammonium molybdate pyrolyzed to remove all water of crystal and part of ammonium ions, and its crystal shape changed from (NH4)6Mo7O24•4H2O to (NH4)2Mo4O13. Meanwhile, the protection performance of metal-impregnated samples against sulfur dioxide was also evaluated. The evaluation results show that the two-component Cu-Ni impregnated sample had the strongest SO2 protection performance under the calcination condition of 150 °C.

The Relationship between the Structural Characteristics of α-Fe2O3 Catalysts and Their Lattice Oxygen Reactivity Regarding Hydrogen.

In this paper, the relationship between the structural features of hematite samples calcined in the interval of 800-1100 °C and their reactivity regarding hydrogen studied in the temperature-programmed reaction (TPR-H2) was studied. The oxygen reactivity of the samples decreases with the increasing calcination temperature. The study of calcined hematite samples used X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), and Raman spectroscopy, and their textural characteristics were studied also. According to XRD results, hematite samples calcined in the temperature range under study are monophase, represented by the α-Fe2O3 phase, in which crystal density increases with increasing calcination temperature. The Raman spectroscopy results also register only the α-Fe2O3 phase; the samples consist of large, well-crystallized particles with smaller particles on their surface, having a significantly lower degree of crystallinity, and their proportion decreases with increasing calcination temperature. XPS results show the α-Fe2O3 surface enriched with Fe2+ ions, whose proportion increases with increasing calcination temperature, which leads to an increase in the lattice oxygen binding energy and a decrease in the α-Fe2O3 reactivity regarding hydrogen.

Catalytic dehydration of fructose to 5-hydroxymethylfurfural over mesoporous Nb-W oxide solid acid catalyst

In this study, a mesoporous Nb-W oxide solid acid catalyst was synthesized and characterized in detail by TEM, N2 physisorption, and Py-FTIR. Effects of the calcination temperature on the pore structure and acid properties were investigated. The results showed that increasing calcination temperature from 400 °C to 600 °C remarkably affected the characteristics of mesoporous Nb-W oxides, with a decrease in specific surface area, pore volume, and acid amount, but an increase in pore size from 5.1 nm to 10.4 nm. Furthermore, a notable decrease was found in both the fructose conversion and HMF yield in the dehydration of fructose to HMF over Nb-W oxides when increasing the calcination temperature, and the catalyst could keep high catalytic activity and selectivity after recycling 4 times. Solvents also played a key role in the fructose dehydration to HMF over the Nb-W oxides, and DMSO was the optimized solvent. 1H NMR and 13C NMR experiments revealed that the key intermediate, 4-hydroxy-5-hydroxymethyl-4,5-dihydrofuran-2-carbaldehyde, could generate in DMSO but not in other solvents including NMP, DMF, DMAC, and EG.

ELECTROCHEMICAL OZONE GENERATION FOR PALM OIL MILL WASTEWATER TREATMENT USING NICKEL/ANTIMONY DOPED TIN OXIDE ANODES

Ozonation have been employed in organic matter degradation and discoloration process of wastewater. In this study, nickel-antimony doped tin oxide (NATO) anode was employed to generate ozone for palm oil mill effluent (POME) wastewater treatment. NATO was synthesized varying Ni concentrations and calcination temperatures. The materials were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) techniques. All materials showed rutile structure. The electrode displayed a smooth cracked mud surface morphology. Regarding the oxidation state, the binding energies of the Sb 3d3/2 peak were observed at 540.62 eV and 541.51 eV corresponding to Sb3+ and Sb5+, respectively. The key findings show that increasing calcination temperature increases ozone current efficiency obtained from the absorbances of dissolved ozone in liquid phase and current density, which decreases with increasing Ni content. The highest current efficiency and current density (i.e. ca. 30% and 0.18 Acm-2 in 1 M H2SO4 at 2.7V) was achieved at 2%mole ratio Ni content calcined at 650°C. Regarding POME treatment, discoloration and degradation efficiency increased with electrolysis time from the initial chemical oxygen demand (COD) and total organic carbon (TOC) of 1,780 and 96 mgL-1, respectively under the aforementioned conditions. The highest removal efficiency of 80% was achieved within 10 min discoloration and 15 min for TOC and COD. The electrochemical ozone generation using NATO anode have shown high efficiency in the POME treatment due to •OH radicals and O3. NATO is a promising electrocatalyst candidate for wastewater treatment.

Fabrication and catalytic evaluation of Ni/CaO–Al2O3 in glycerol steam reforming: Effect of Ni loading

The present study aims to assess the catalytic activity of the Ni/CaO–Al2O3 catalysts with different Ni loadings (2.5, 5, 10, 15, and 20 wt %) for H2 generation via the glycerol steam reforming (GSR). The support was prepared by the mechanochemical method, and then the various contents of nickel were impregnated on the support surface. The synthesized samples were characterized by BET, XRD, H2- TPR, CO2-TPD, TPO, FTIR, and SEM analyses. High stable catalytic activity was reported for the prepared catalysts. Among the investigated catalysts, 15%Ni/CaO–Al2O3 with the highest reducibility, proper BET area (96.6 m2 g−1), and suitable basicity possessed the highest catalytic performance with glycerol conversion of 99.4% at 700 °C. All the samples had high stability after 5 h, and the 15%Ni/CaO–Al2O3 showed 97.5% glycerol conversion at 550 °C without any decline in glycerol conversion durin 15 h time on stream. It was also found that glycerol conversion decreased with the increase in gas hourly space velocity and calcination temperature.