Photocatalytic Activity of Fe/Ti Mixed Oxide for Degrading Humic Acid in Water

2013 ◽  
Vol 717 ◽  
pp. 95-100 ◽  
Author(s):  
I.H. Kim ◽  
W.S. Kim ◽  
D.S. Rhee
Keyword(s):  
Titanium Dioxide ◽  
Iron Oxide ◽  
Humic Acid ◽  
Mixed Oxide ◽  
Photocatalytic Oxidation ◽  
Mixed Oxides ◽  
Environmental Pollutant ◽  
Oxide Surface ◽  
Active Components ◽  
Coated Granules

The comparative experiments for removing humic acid as environmental pollutant were conducted by adsorption on iron oxide, photooxidation in the presence of titanium dioxide catalyst and combined adsorption-photooxidation by iron-titanium mixed metal oxides, where all these active components were immobilized on polypropylene granules. The main purpose of the work was the combination of adsorption and photocatalytic oxidation processes to remove humic acid. The granules with iron-titanium mixed oxide for treating humic acid gave much better results with 1.2~3 times higher removal rates comparing to the other two single coated oxides at certain pH values. And the order of removal efficiency according to pH was the same as for single iron oxide-coated granules. The ratio 1:2 of iron oxide/titanium dioxide was found optimal for maximal decolorization of humic acid solution. The total organic carbon decrease of humic acid in each experiments, when it was pre-equilibrated with mixed oxides-coated granules in the dark for 30 min and without pre-equilibration, was very similar. The results suggested that the mechanism of humic acid removal may be not only a respectively combined adsorption and photooxidation by iron oxide and titanium oxides, but an enhanced photooxidation reaction as a result of concentrating humic acid on titanium oxide surface by iron oxide.

scholarly journals Direct Decomposition of NO over Co-Mn-Al Mixed Oxides: Effect of Ce and/or K Promoters

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 808
Author(s):  
Květa Jirátová ◽  
Kateřina Pacultová ◽  
Kateřina Karásková ◽  
Jana Balabánová ◽  
Martin Koštejn ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Chemical Properties ◽  
Surface Concentration ◽  
Direct Decomposition ◽  
No Decomposition ◽  
High Catalytic Activity ◽  
Active Components ◽  
Mixed Oxide Catalysts

Co-Mn-Al mixed oxides promoted by potassium are known as active catalysts for the direct decomposition of nitric oxide (NO). In this study, the answer to the following question has been considered: does the presence of cerium in K-promoted Co-Mn-Al catalysts substantially affect the physical-chemical properties, activity, and stability in direct NO decomposition? The Co-Mn-Al, Co-Mn-Al-Ce, and Co-Mn-Al-Ce-K mixed oxide catalysts were prepared by the precipitation of corresponding metal nitrates with a solution of Na2CO3/NaOH, followed by the washing of the precipitate and calcination. Two other catalysts were prepared by impregnation of the Ce-containing catalysts with Co and Co+K nitrates. After calcination, the solids were characterized by chemical analysis, XRD, N2 physisorption, FTIR, temperature-programmed reduction, CO2 and O2 desorption (H2-TPR, CO2-TPD, O2-TPD), and X-ray photoelectron spectrometry (XPS). Cerium and especially potassium occurring in the catalysts affected the basicity, reducibility, and surface concentration of active components. Adding cerium itself did not contribute to the increase in catalytic activity, whereas the addition of cerium and potassium did. Catalytic activity in direct NO decomposition depended on combinations of both reducibility and the amount of stronger basic sites determined in the catalysts. Therefore, the increase in cobalt concentration itself in the Co-Mn-Al mixed oxide catalyst does not determine the achievement of high catalytic activity in direct NO decomposition.

Sol-Gel Titania and Titania-Silica Mixed Oxides Photocatalysts

2010 ◽  
Vol 162 ◽  
pp. 221-238 ◽  
Author(s):  
Rafael van Grieken ◽  
José Aguado ◽  
María José López-Muñoz ◽  
Javier Marugán
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Surface Area ◽  
Photocatalytic Oxidation ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Textural Properties ◽  
Total Surface Area ◽  
Band Gap Energy ◽  
Titania Incorporation

This paper presents a review of the work published by the authors on the synthesis, characterization and evaluation of the photocatalytic activity of TiO2/SiO2 materials. The use of titania-silica mixed oxides photocatalysts is proposed basically as a process improvement to overcome the difficulties of recovering titania from the slurries after the photocatalytic treatment of contaminated waters. To understand the mechanism governing the photocatalytic activity of these materials, several titania-silica photocatalysts have been prepared through a sol-gel method that allows controlling the main variables to obtain materials with different textural properties, degree of titania incorporation, dispersion of the photoactive phase and crystallinity of titanium dioxide. The samples have been characterized in depth, looking for correlations between the main physicochemical properties (TiO2 crystallite size, band gap energy and titania surface area) and the activity shown in the photocatalytic oxidation of cyanide, selected as model pollutant. The results suggest that the photocatalytic activity is strongly influenced by the quality of the titania crystal network, which in turn is improved by the use of a hydrothermal crystallization procedure. Additionally, the evaluation of the fraction of the total surface area corresponding to titania is mandatory for comparing the catalytic activity of different materials in processes in which titanium dioxide is the only phase catalytically active and silica behaves as an inert support.

scholarly journals Properties of Silicone Rubber-Based Composites Reinforced with Few-Layer Graphene and Iron Oxide or Titanium Dioxide

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1550
Author(s):  
Vineet Kumar ◽  
Anuj Kumar ◽  
Minseok Song ◽  
Dong-Joo Lee ◽  
Sung-Soo Han ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Titanium Dioxide ◽  
Iron Oxide ◽  
Stress Relaxation ◽  
Silicone Rubber ◽  
Room Temperature ◽  
Relaxation Rates ◽  
Layer Graphene ◽  
Few Layer Graphene ◽  
Mechanical Actuation

The increasing demand for polymer composites with novel or improved properties requires novel fillers. To meet the challenges posed, nanofillers such as graphene, carbon nanotubes, and titanium dioxide (TiO2) have been used. In the present work, few-layer graphene (FLG) and iron oxide (Fe3O4) or TiO2 were used as fillers in a room-temperature-vulcanized (RTV) silicone rubber (SR) matrix. Composites were prepared by mixing RTV-SR with nanofillers and then kept for vulcanization at room temperature for 24 h. The RTV-SR composites obtained were characterized with respect to their mechanical, actuation, and magnetic properties. Fourier-transform infrared spectroscopy (FTIR) analysis was performed to investigate the composite raw materials and finished composites, and X-ray photoelectron spectroscopy (XPS) analysis was used to study composite surface elemental compositions. Results showed that mechanical properties were improved by adding fillers, and actuation displacements were dependent on the type of nanofiller used and the applied voltage. Magnetic stress-relaxation also increased with filler amount and stress-relaxation rates decreased when a magnetic field was applied parallel to the deformation axes. Thus, this study showed that the inclusion of iron oxide (Fe3O4) or TiO2 fillers in RTV-SR improves mechanical, actuation, and magnetic properties.

scholarly journals Magnetic iron oxide/clay nanocomposites for adsorption and catalytic oxidation in water treatment applications

2020 ◽  
Vol 18 (1) ◽  
pp. 1148-1166
Author(s):  
Ganjar Fadillah ◽  
Septian Perwira Yudha ◽  
Suresh Sagadevan ◽  
Is Fatimah ◽  
Oki Muraza
Keyword(s):  
Iron Oxide ◽  
Water Treatment ◽  
Photocatalytic Oxidation ◽  
Low Cost ◽  
Synthesis Method ◽  
Chemical Oxidation ◽  
Magnetic Iron Oxide ◽  
Oxidation Processes ◽  
Recent Developments ◽  
Physical And Chemical

AbstractPhysical and chemical methods have been developed for water and wastewater treatments. Adsorption is an attractive method due to its simplicity and low cost, and it has been widely employed in industrial treatment. In advanced schemes, chemical oxidation and photocatalytic oxidation have been recognized as effective methods for wastewater-containing organic compounds. The use of magnetic iron oxide in these methods has received much attention. Magnetic iron oxide nanocomposite adsorbents have been recognized as favorable materials due to their stability, high adsorption capacities, and recoverability, compared to conventional sorbents. Magnetic iron oxide nanocomposites have also been reported to be effective in photocatalytic and chemical oxidation processes. The current review has presented recent developments in techniques using magnetic iron oxide nanocomposites for water treatment applications. The review highlights the synthesis method and compares modifications for adsorbent, photocatalytic oxidation, and chemical oxidation processes. Future prospects for the use of nanocomposites have been presented.

Phase Identification in Mixed Oxide Capacitors Using Electron Backscatter Diffraction and X-Ray Diffraction

2000 ◽  
Vol 6 (S2) ◽  
pp. 944-945
Author(s):  
P. M. Adams ◽  
C. T. Hoskinson ◽  
R. Witt
Keyword(s):  
Dielectric Properties ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Electron Backscatter Diffraction ◽  
Phase Identification ◽  
Electronic Systems ◽  
Oxide Ceramic ◽  
Backscatter Diffraction ◽  
Titanium Silicon ◽  
New Phase

A group of mixed oxide ceramic capacitors used in several electronic systems recently failed as a result of voltage breakdown in the specified test ranges. These capacitors consist predominantly of mixed oxides of magnesium, titanium, silicon and aluminum (with minor amounts of strontium and calcium) and contain palladium mesh electrodes. Preliminary results suggest that phase transformations have occurred in some lots of capacitors that have been over-fired as a result of a manufacturing change. Several years’ production of capacitors has potentially been affected. The formation of a phase with inferior dielectric properties, and which can exhibit semiconducting properties (P/N junction), probably resulted in the failure of the capacitors. This new phase is typically rich in strontium and is only present at levels of several volume percent. The low concentration of this phase has made its identification difficult. If this new phase could be identified it might be possible to determine/establish if its dielectric properties are consistent with the proposed failure mechanism.

scholarly journals Anodic Titanium Dioxide Nanotubes for Magnetically Guided Therapeutic Delivery

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Morteza Hasanzadeh Kafshgari ◽  
Delf Kah ◽  
Anca Mazare ◽  
Nhat Truong Nguyen ◽  
Monica Distaso ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Iron Oxide ◽  
Iron Oxide Nanoparticles ◽  
Hela Cells ◽  
Release Kinetics ◽  
Drug Loading ◽  
Oxide Nanoparticles ◽  
Site Specific ◽  
Therapeutic Drugs ◽  
Wide Range

Abstract Hollow titanium dioxide (TiO2) nanotubes offer substantially higher drug loading capacity and slower drug release kinetics compared to solid drug nanocarriers of comparable size. In this report, we load TiO2 nanotubes with iron oxide nanoparticles to facilitate site-specific magnetic guidance and drug delivery. We generate magnetic TiO2 nanotubes (TiO2NTs) by incorporating a ferrofluid containing Ø ≈ 10 nm iron oxide nanoparticles in planar sheets of weakly connected TiO2 nanotubes. After thermal annealing, the magnetic tubular arrays are loaded with therapeutic drugs and then sonicated to separate the nanotubes. We demonstrate that magnetic TiO2NTs are non-toxic for HeLa cells at therapeutic concentrations (≤200 µg/mL). Adhesion and endocytosis of magnetic nanotubes to a layer of HeLa cells are increased in the presence of a magnetic gradient field. As a proof-of-concept, we load the nanotubes with the topoisomerase inhibitor camptothecin and achieve a 90% killing efficiency. We also load the nanotubes with oligonucleotides for cell transfection and achieve 100% cellular uptake efficiency. Our results demonstrate the potential of magnetic TiO2NTs for a wide range of biomedical applications, including site-specific delivery of therapeutic drugs.

A First-Principles Study of Impurity-Enhanced Adhesion and Lubricity of Graphene on Iron Oxide Surface

2021 ◽  
Vol 125 (7) ◽  
pp. 4310-4321
Author(s):  
Huong T. T. Ta ◽  
A. Kiet Tieu ◽  
Hongtao Zhu ◽  
Haibo Yu ◽  
Nam V. Tran
Keyword(s):  
Iron Oxide ◽  
First Principles ◽  
Oxide Surface ◽  
First Principles Study
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