scholarly journals Nano-Sized Fe(III) Oxide Particles Starting from an Innovative and Eco-Friendly Synthesis Method

Nanomaterials ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 323 ◽  
Author(s):  
Ludovico Macera ◽  
Giuliana Taglieri ◽  
Valeria Daniele ◽  
Maurizio Passacantando ◽  
Franco D’Orazio
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Ambient Pressure ◽  
Synthesis Method ◽  
Hematite Nanoparticles ◽  
X Ray

This paper introduces an original, eco-friendly and scalable method to synthesize ferrihydrite nanoparticles in aqueous suspensions, which can also be used as a precursor to produce α-hematite nanoparticles. The method, never used before to synthesize iron oxides, is based on an ion exchange process allowing to operate in one-step, with reduced times, at room temperature and ambient pressure, and using cheap or renewable reagents. The influence of reagent concentrations and time of the process on the ferrihydrite features is considered. The transformation to hematite is then analyzed and discussed in relation to different procedures: (1) A natural aging in the water at room temperature; and (2) heat treatments at different temperatures and times. Structural and morphological features of the obtained nanoparticles are investigated by means of several techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, thermal analysis, nitrogen adsorption and magnetic measurements. Ferrihydrite shows the typical spherical morphology and a very high specific surface area of 420 m2/g. Rhombohedral or plate-like hexagonal hematite nanoparticles are obtained by the two procedures, characterized by dimensions of 50 nm and 30 nm, respectively, and a specific surface area up to 57 m2/g, which is among the highest values reported in the literature for hematite NPs.

CO2 utilization by dry reforming of CH4 over mesoporous Ni/KIT-6 catalyst

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Congming Tang ◽  
Juan Huang ◽  
Dong Zhang ◽  
Qingqing Jiang ◽  
Guilin Zhou
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Pore Diameter ◽  
Co2 Utilization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Performances

Abstract The mesoporous Ni/KIT-6 catalysts with different composition were prepared by altering reduction temperatures. In addition, their physicochemical properties were characterized by X-ray diffraction, in-situ X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller techniques. The results shown that the specific surface area, composition and metallic Ni crystallinity of the Ni/KIT-6 catalyst were significantly affected by reduction temperatures. The catalytic performances of the prepared Ni/KIT-6 catalysts were evaluated via the CO2 reforming of CH4 into syngas and followed the order: RT0 < RT250 < RT300 < RT350 < RT400 < RT450 ≈ RT500. The specific surface area, pore volume, pore diameter, and Ni0 content of the most representative RT450 catalyst among of them were 646.7 m2 g−1, 0.92 cm3 g−1, 6.5 nm, and 30.9%, respectively. The CH4 and CO2 conversions of RT450 catalyst reached to 69.0 and 39.4% under a reaction temperature of 600 °C, respectively. The CO selectivity was greater than 49% and the RT450 catalyst had good stability.

scholarly journals Enhanced Photocatalytic Activity for Degradation of Methyl Orange over Silica-Titania

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Yaping Guo ◽  
Shaogui Yang ◽  
Xuefei Zhou ◽  
Chunmian Lin ◽  
Yajun Wang ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Anatase Phase ◽  
Solution Treatment ◽  
X Ray

Silica-modified titania (SMT) powders with different atomic ratios of silica to titanium (Rx) were successfully synthesized by a simple ultrasonic irradiation technique. The prepared samples were characterized by X-ray diffraction (XRD), FT-IR spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultraviolet visible spectroscopy. The specific surface area was measured according to BET theory. Results indicate that the addition of silica to titania can suppress the crystalline size growth and the transformation of anatase phase to rutile phase of titania, enlarge specific surface area of the titania particles, and result in a blue shift of absorption edge compared to pure titania. The photocatalytic activity of the SMT samples was evaluated by decolorizing methyl orange aqueous solutions under UV-visible light irradiation. It was found in our study that this activity was affected by silica content, calcination temperature, H2SO4, and oxidants such as KIO4, (NH4)2S2O8and H2O2. The results reveal that the photocatalytic activity of 0.1-SMT catalyst is the best among all samples calcined at550°C for 1 h and it is 1.56 times higher than that of Degussa P-25 titania, which is a widely used commercial TiO2made by Germany Degussa company and has been most widely used in industry as photocatalyst, antiultraviolet product, and thermal stabilizer. The optimal calcination temperature for preparation was550°C. The photocatalytic activity of SMT samples is significantly enhanced by H2SO4solution treatment and oxidants.

scholarly journals Surface Structure Engineering of Nanosheet-Assembled NiFe2O4 Fluffy Flowers for Gas Sensing

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 297
Author(s):  
Xiaofeng Wang ◽  
Xu Li ◽  
Guozheng Zhang ◽  
Zihao Wang ◽  
Xue-Zhi Song ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Structure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Gas Sensing ◽  
Nitrogen Adsorption ◽  
X Ray ◽  
Adsorption Desorption ◽  
Sensing Performance

In this work, we present a strategy to improve the gas-sensing performance of NiFe2O4 via a controllable annealing Ni/Fe precursor to fluffy NiFe2O4 nanosheet flowers. X-ray diffraction (XRD), a scanning electron microscope (SEM), nitrogen adsorption–desorption measurements and X-ray photoelectron spectroscopy (XPS) were used to characterize the crystal structure, morphology, specific surface area and surface structure. The gas-sensing performance was tested and the results demonstrate that the response was strongly influenced by the specific surface area and surface structure. The resultant NiFe2O4 nanosheet flowers with a heating rate of 8 °C min−1, which have a fluffier morphology and more oxygen vacancies in the surface, exhibited enhanced response and shortened response time toward ethanol. The easy approach facilitates the mass production of gas sensors based on bimetallic ferrites with high sensing performance via controlling the morphology and surface structure.

scholarly journals Structural, photocatalytic and surface analysis of Nb/Ag codoped TiO2 mesoporous nanoparticles

2020 ◽  
Vol 96 (3) ◽  
pp. 728-741
Author(s):  
Mahtab Gorgani ◽  
Behzad Koozegar Kaleji
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Sol Gel ◽  
Band Gap Energy ◽  
Xenon Lamp ◽  
X Ray ◽  
Mesoporous Nanoparticles

Abstract In this study, several TiO2 mesoporous nanoparticles with different mol% of niobium and silver were synthesized using the sol–gel method. The crystalline phase, chemical state, photocatalytic and optical properties, specific surface area, and morphology of mesoporous nanoparticles were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–Vis reflective spectroscopy (UV–Vis), Brunauer–Emmett–Teller-specific surface area (BET) and field emission scanning electron microscopy (FESEM). With increasing calcination temperature, the photocatalytic activity of the samples gradually increased due to the improvement of crystallization of the anatase and rutile phases. Nb/Ag codoping sample calcined at 550 °C has reduced the band gap energy (3.17 eV to 3.06 eV) and improved the photocatalytic properties of samples under visible light (xenon lamp, 200 W for 1 h and 2 h). Doped TiO2 mesoporous nanoparticles were shown to have the highest photocatalytic activity as compared with the pure TiO2 nanoparticles. The best photocatalytic efficiency of codoped TiO2 mesoporous nanoparticles was observed for the TNA3 sample calcined under 550 °C, containing molar contents of Nb (0.5 mol%) and Ag (1 mol%) dopant ions with 95.60% efficiency.

scholarly journals Photodegradation of Microcystin-LR Using Visible Light-Activated C/N-co-Modified Mesoporous TiO2 Photocatalyst

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1027 ◽  
Author(s):  
Tamer Khedr ◽  
Said El-Sheikh ◽  
Adel Ismail ◽  
Ewa Kowalska ◽  
Detlef Bahnemann
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Ph Value ◽  
Hydrothermal Process ◽  
Tio2 Photocatalyst ◽  
X Ray

Microcystin-LR (MC-LR), a potent hepatotoxin produced by the cyanobacteria, is of increasing concern worldwide because of severe and persistent impacts on humans and animals by inhalation and consumption of contaminated waters and food. In this work, MC-LR was removed completely from aqueous solution using visible-light-active C/N-co-modified mesoporous anatase/brookite TiO2 photocatalyst. The co-modified TiO2 nanoparticles were synthesized by a one-pot hydrothermal process, and then calcined at different temperatures (300, 400, and 500 °C). All the obtained TiO2 powders were analyzed by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM), specific surface area (SSA) measurements, ultraviolet-visible diffuse reflectance spectra (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and photoluminescence (PL) analysis. It was found that all samples contained mixed-phase TiO2 (anatase and brookite), and the content of brookite decreased with an increase in calcination temperature, as well as the specific surface area and the content of non-metal elements. The effects of initial pH value, the TiO2 content, and MC-LR concentration on the photocatalytic activity were also studied. It was found that the photocatalytic activity of the obtained TiO2 photocatalysts declined with increasing temperature. The complete degradation (100%) of MC-LR (10 mg L−1) was observed within 3 h, using as-synthesized co-modified TiO2 (0.4 g L−1) at pH 4 under visible light. Based on the obtained results, the mechanism of MC-LR degradation has been proposed.

scholarly journals Visible-light-induced peroxymonosulfate activation over ZnFe2O4 fine nanoparticles for ofloxacin degradation

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Lei Sun ◽  
Gang Cao ◽  
Musheng Xu ◽  
Gong Cheng ◽  
Dongsheng Xia ◽  
...  
Keyword(s):  
Visible Light ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Kinetic Constant ◽  
Unintended Consequences ◽  
Degradation Efficiency ◽  
Order Kinetic ◽  
X Ray

Widespread overuse and misuse of antibiotics has led to unintended consequences, and it is necessary to find effective ways to remove antibiotics. In this study, a visible-light-response photocatalyst zinc ferrite (ZnFe2O4) was synthesized via a hydrothermal method. Meanwhile, the X-ray diffraction, Brunauer–Emmett–Teller, scanning electron microscope, X-ray photoelectron spectroscopy, and Fourier transform infrared spectra analysis were applied to characterize the structure, morphology, and physicochemical properties of the ZnFe2O4. The results indicated that the ZnFe2O4 was circular granular morphology with a particle size of approximately 30–50 nm and the noticeable intergranular agglomeration. The specific surface area, pore volume, and pore diameter of the ZnFe2O4 were determined to be 126.8655 m2/g, 0.2046 cm3/g, and 64.5190 Å, respectively, representing that the ZnFe2O4 had a large specific surface area. Moreover, the enhancement of degradation efficiency of ofloxacin (OFL) by peroxymonosulfate (PMS) under the visible light (Vis) was systematically evaluated. The results exhibited that the ZnFe2O4 achieved the relatively optimum catalytic activity with 80.9% of OFL degradation efficiency in 30 min at pH 6.0 under the PMS concentration of 100 mg/L and the corresponding pseudo-first-order kinetic constant of OFL degradation was 0.0438 min–1. In addition, the effects of ZnFe2O4 dosage, PMS concentration, initial OFL concentration, solution pH, and water matrix on the OFL degradation were comprehensively investigated in the Vis/PMS/ZnFe2O4 process. Furthermore, the ZnFe2O4 exhibited excellent stability and reusability for OFL degradation. The Vis/PMS/ZnFe2O4 process would be a reliable alternative for the degradation of OFL-like antibiotics to solve the increasingly serious problem of antibiotic pollution.

scholarly journals Synthesis of Ag3PO4 using Hydrophylic Polymer and Their Photocatalytic Activities under Visible Light Irradiation

2017 ◽  
Vol 12 (2) ◽  
pp. 206 ◽  
Author(s):  
Uyi Sulaeman ◽  
Bin Liu ◽  
Shu Yin ◽  
Tsugio Sato
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Visible Light Irradiation ◽  
Photoelectron Spectroscopy ◽  
Light Irradiation ◽  
X Ray ◽  
Photocatalytic Activities

The highly active Ag3PO4 photocatalysts were successfully synthesized using the hydrophylic polymer of PVA (polyvinyl alcohol), PEG (polyethylene glycol) and PVP (polyvinyl pyrrolidone). The products were characterized using X-ray diffraction (XRD), Diffuse reflection spectroscopy (DRS), Field emission scanning electron microscope (FE-SEM), Brunauer–Emmett–Teller (BET) specific surface area, and X-ray photoelectron spectroscopy (XPS). Photocatalytic activities were evaluated using decomposition of Rhodamine B (RhB) under visible light irradiation. The results showed that the PVA, PEG, and PVP increased the specific surface area and enhanced the photocatalytic activity of Ag3PO4. The highest photocatalytic activity could be observed in Ag3PO4 synthesized with PVA, mainly due to an increase in electron excitation induced by PVA chemically adsorbed on the surface. Copyright © 2017 BCREC Group. All rights reservedReceived: 13rd November 2016; Revised: 10th February 2017; Accepted: 10th February 2017How to Cite: Sulaeman, U., Liu, B., Yin, S., Sato, T. (2017). Synthesis of Ag3PO4 using Hydrophylic Polymer and Their Photocatalytic Activities under Visible Light Irradiation. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (2): 206-211 (doi:10.9767/bcrec.12.2.767.206-211)Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.2.767.206-211 

scholarly journals Nanocomposite of CeO2 and High-Coercivity Magnetic Carrier with Large Specific Surface Area

2016 ◽  
Vol 2016 ◽  
pp. 1-13
Author(s):  
Alice Reznickova Mantlikova ◽  
Jiri Plocek ◽  
Barbara Pacakova ◽  
Simona Kubickova ◽  
Ondrej Vik ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Synthesis Method ◽  
High Specific Surface Area ◽  
High Coercivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

We succeeded in the preparation of CoFe2O4/CeO2 nanocomposites with very high specific surface area (up to 264 g/m2). First, highly crystalline nanoparticles (NPs) of CoFe2O4 (4.7 nm) were prepared by hydrothermal method in water-alcohol-oleic acid system. The oleate surface coating was subsequently modified by ligand exchange to citrate. Then the NPs were embedded in CeO2 using heterogeneous precipitation from diluted Ce3+ sulphate solution. Dried samples were characterized by Powder X-Ray Diffraction, Energy Dispersive X-Ray Analysis, Scanning and Transmission Electron Microscopy, Mössbauer Spectroscopy, and Brunauer-Emmett-Teller method. Moreover, detailed investigation of magnetic properties of the bare NPs and final composite was carried out. We observed homogeneous embedding of the magnetic NPs into the CeO2 without significant change of their size and magnetic properties. We have thus demonstrated that the proposed synthesis method is suitable for preparation of extremely fine CeO2 nanopowders and their nanocomposites with NPs. The morphology and magnetic nature of the obtained nanocomposites make them a promising candidate for magnetoresponsive catalysis.

Preparation, Characterization and Oxygen Gas Sensitivity of Nanosolid Superacid SO42-/ LaCoFeO4

2011 ◽  
Vol 694 ◽  
pp. 209-213 ◽  
Author(s):  
De Juan Lin ◽  
Shui Fa Shen ◽  
Qing Hua Wang ◽  
Lin Jie Wang ◽  
Nai Sheng Chen ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Photoelectron Spectroscopy ◽  
Oxygen Sensor ◽  
Water Solution ◽  
Sensor Technology ◽  
Gas Sensitivity ◽  
X Ray ◽  
Working Temperature

Metal oxides have been applied in gas sensor technology while suffering poor sensitivity and high working temperature. In this work, a novel method has been adopted to improve these problems of the sensors. A mixture of Fe3+, La3+, Co2+ (Fe3+: La3+: Co2+ =10:3:1) and dispersing agent in water solution was precipitated by adding NH4+(pH=9) under agitation. The precipitate was filtered, washed and drying, then immersed with 0.5M (NH4)2SO4 in 12hr. Superacid SO42-/ LaCoFeO4 was prepared after calcined at 673K for 1h. The thick film units for oxygen sensor were dintered at 673K for 3h.The structure of this catalyst has been characterized by means of powder X-ray diffraction (XRD), transmission electron microscope (TEM), IR, X-ray photoelectron spectroscopy (XPS) and specific surface area measurements. The result indicated that the SO42-/ LaCoFeO4 grain sizes (10nm) were smaller and the specific surface area (126M2/g ) was higher than the pure metal oxide LaCoFeO4. The acid strength was measured by the model reaction of ethyl acetate synthesis and attributed as superacid. In addition, the SO42- was combined with metal ions in a bidentate fashion. The binding energy of SO42-/ LaCoFeO4 was larger than that of LaCoFeO4. The sensitivity as well as the working temperature is improved by comparison with the pure LaCoFeO4 phase. The relationship between the oxygen sensing properties and structure has also been discussed.

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