scholarly journals Photocatalytic Reduction of AuCl4- by Fe3O4/SiO2/TiO2 Nanoparticles

2020 ◽  
Keyword(s):  
Tio2 Nanoparticles ◽  
Uv Light ◽  
Electronic Waste ◽  
Sol Gel ◽  
Photocatalytic Reduction ◽  
Light Illumination ◽  
Magnetite Fe3o4 ◽  
Sol Gel Process ◽  
Competitive Reduction ◽  
Closed Reactor

<p>Metallurgy and recovery of gold in electronic waste sometimes involve the reduction of tetrachloroaurate ion (AuCl4-) to elemental gold form. Currently, for the reduction of tetrachloroaurate ion, people use reducing agents such as hydroquinone and sodium borohydride. Photocatalysts of Fe3O4/SiO2/TiO2 nanoparticles were prepared and tested for the reduction of tetrachloroaurate ion under UV light illumination. The magnetite (Fe3O4) nanoparticle was first prepared by coprecipitation and sonication, followed by SiO2 and TiO2 coatings via the sol-gel process and calcination. The products were confirmed by XRD and TEM. The photocatalytic reduction of tetrachloroaurate ion was performed in a closed reactor equipped with a UV light source. The results indicated that Fe3O4/SiO2/TiO2 nanoparticles were successfully prepared, which retained good magnetic and photocatalytic properties. The photocatalytic reaction is best performed at a pH of 5 under UV irradiation for 2 h, which is capable of reducing 96% of the tetrachloroaurate present in the mixture. The co-presence of Ni2+ and Cu2+ ions in the solution leads to a decrease in yield due to competitive reduction and adsorption. The photocatalyst is recoverable by the use of a magnetic bar and may find application for gold recovery and metallurgy.</p>

Photocatalytic reduction of Cr(VI) in aqueous solution using TiO2 nanoparticles prepared with various alcohols as solvent

2012 ◽  
Vol 66 (6) ◽  
pp. 1333-1339 ◽  
Author(s):  
Young Ku ◽  
Chia–Nan Lin ◽  
Wei–Ming Hou
Keyword(s):  
Phase Transformation ◽  
Tio2 Nanoparticles ◽  
Surface Area ◽  
Hexavalent Chromium ◽  
Sol Gel ◽  
Photocatalytic Reduction ◽  
Structure Characterization ◽  
Phase Transformation Temperature ◽  
Reduction Activity ◽  
Sol Gel Process

TiO2 nanoparticles were prepared with various linear alkyl chains of alcohols under a sol–gel process. The structure characterization and the photocatalytic reduction of hexavalent chromium of the TiO2 nanoparticles were investigated. The phase transformation temperature, crystal aggregation and surface area of prepared TiO2 samples were found to be strongly influenced by alcohol used. The phase transformation from anatase to rutile was retarded and the surface area was reduced for TiO2 prepared with alcohols of longer alkyl chain. TiO2 nanoparticles prepared with methanol or ethanol exhibited higher photocatalytic reduction activity of hexavalent chromium possibly due to greater and more positively charged surface area.

Optic and Piezoelectric Coupling in the Sol-Gel PLZT Electroceramics

2012 ◽  
Vol 730-732 ◽  
pp. 129-134
Author(s):  
Lucjan Kozielski ◽  
Malgorzata Plonska
Keyword(s):  
Uv Light ◽  
Sol Gel ◽  
Light Illumination ◽  
Piezoelectric Effects ◽  
Piezoelectric Coupling ◽  
Wireless Device ◽  
Organometallic Precursors ◽  
Gain Adjustment ◽  
Piezoelectric Transformers ◽  
Sintering Method

PZT ceramic system with presence of La contents, have been proposed and prepared using sol gel sintering method for practical application of photostriction, which is the superposition of photovoltaic and piezoelectric effects. Such a ceramics produced by conventional mixing oxide method does not exhibit photostrictive properties due to the defects and inhomogeneous distribution of grains and pores. In this study, an investigated lanthanium(III) doped PZT ceramics were obtained by sol-gel technique from the organometallic precursors. It was found that fabricated material were effective in the enhancement of photovoltaic and photostrictive properties. Consequently, lanthanium influence deviation of piezoelectric parameters were studied as a function UV light illumination. For the determination lighting dependancy of the transformation parameters the resonant and antiresonant method was implemented. The improved Piezoelectric Transformer structure successfully changed gain characteristics proportionally to light intensity. The authors invention of a light driven output gain adjustment in Piezoelectric Transformers (PT) yields a novel “smart” multifunctional wireless device. This new created application area can be utilized in self-adopting shutters in photo cameras due to improved sensitivity to surrounding illumination conditions.

Photocatalytically Active Cotton Fabrics Produced with Anatase Synthesized Using a Low-Temperature Sol-Gel Process

2018 ◽  
Vol 762 ◽  
pp. 408-412
Author(s):  
Raivis Eglītis ◽  
Gundars Mežinskis
Keyword(s):  
Photocatalytic Activity ◽  
Uv Light ◽  
Sol Gel ◽  
Average Particle Size ◽  
Synthesis Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Sol Gel Process ◽  
Anatase Nanoparticles ◽  
Pre Treatment

In this work two different hydrosols were used to impregnate a commercially available cotton fabric with anatase nanoparticles to give it photocatalytic activity. To increase the activity, different pre-treatment methods were applied. The nanoparticle size was determined using dynamic light scattering and x-ray diffraction and the fabrics were examined using scanning electron microscopy. Photocatalytic activity was measured using the degradation of methyl-orange while irradiating the samples with UV light. The synthesis method allowed to produce anatase with an average particle size of 32 to 37 nm depending on the synthesis method used.

scholarly journals Immobilization of Bacillus licheniformis using Fe3O4@SiO2 nanoparticles for the development of bacterial bioreactor

2019 ◽  
Vol 35 (2) ◽  
pp. 854-862
Author(s):  
Ayoub Nadi ◽  
Marouane Melloul ◽  
Aicha Boukhriss ◽  
Elmostafa El-Fahime ◽  
Damien Boyer ◽  
...  
Keyword(s):  
Bacillus Licheniformis ◽  
Fe3o4 Nanoparticles ◽  
Sol Gel ◽  
Sio2 Nanoparticles ◽  
Industrial Applications ◽  
Basic Medium ◽  
Magnetite Fe3o4 ◽  
Sol Gel Process ◽  
Co Precipitation

In the biotechnology field, nanoparticles with a strong magnetic moment can bring attractive and novel potentialities. They are detectable, manipulable, stimulable by a magnetic field and they could be applied as nano-tracers for medical imaging and nano-vectors for transporting therapeutic agents to a target. For our part, we applied Fe3O4 nanoparticles to immobilize bacteria of Moroccan strains in order to develop bacterial bioreactor. For this aim, we got through the synthesis and characterization of magnetite Fe3O4 nanoparticles by co-precipitation in basic medium. The obtained nanoparticles were encapsulated in silica by sol-gel process. The results of this step allowed us to use Fe3O4@SiO2 nanoparticles to immobilize Bacillus licheniformis by adsorption and separate it magnetically. The principle of this system gives us the opportunity to develop a bacterial bioreactor for industrial applications.

One-Step Preparation of Viologen-TiO2 Nanoparticles via a Hydrothermally Assisted Sol-Gel Process for Use in Electrochromic Films and Devices

2018 ◽  
Vol 35 (11) ◽  
pp. 1800142 ◽  
Author(s):  
Ana Viñuales ◽  
Bettina Herbig ◽  
Yolanda Alesanco ◽  
Jesús Palenzuela ◽  
Javier Rodriguez ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Sol Gel ◽  
Sol Gel Process ◽  
One Step

Indium-Sensitized UV Photocatalysts Made from Alkali Titanate Microfibers

2009 ◽  
Vol 620-622 ◽  
pp. 651-654
Author(s):  
Leticia M. Torres-Martínez ◽  
Cecilia Sánchez-Trinidad ◽  
Vicente Rodríguez-González ◽  
Ricardo Gómez
Keyword(s):  
Heat Treatment ◽  
Annealing Time ◽  
Uv Light ◽  
Sol Gel ◽  
Dichlorophenoxyacetic Acid ◽  
Sem Images ◽  
Uv Light Irradiation ◽  
Heat Treated ◽  
Munk Function ◽  
Sol Gel Process

Indium-alkali microfibers doped ceramic were prepared by the sol-gel process. The gels preparation samples, were heat treated at 700°C for different length of time. The products were characterized by means of XRD, SEM-EDS and UV–Vis-DRS. The XRD showed the formation of the Na2Ti6O13 phase whose crystallinity depends on the annealing time. The band gap calculated from the UV–Vis Kubelka-Munk function shows very similar values (3.53-3.55 eV). The SEM images of the indium-alkali titanates show microfiber clumps morphologies of about 5 µm, and the EDS spectra show that In2O3 is on the Na2Ti6O13 surface. The results of the evaluation of the In-Na2Ti6O13 semiconductors in the 2, 4-dichlorophenoxyacetic acid (2, 4-D) photodecomposition under UV light irradiation, show that the photoactivity depends on the time of heat treatment of the samples.

Synthesis and Characterization of SiO2@Y2MoO6:Eu3+ Core–Shell Structured Spherical Phosphors by Sol–Gel Process

2016 ◽  
Vol 16 (4) ◽  
pp. 3914-3920 ◽  
Author(s):  
G. Z Li ◽  
F. H Liu ◽  
Z. S Chu ◽  
D. M Wu ◽  
L. B Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Annealing Temperature ◽  
Uv Light ◽  
Sol Gel ◽  
Spherical Shape ◽  
Core Shell ◽  
X Ray ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Average Size

SiO2@Y2MoO6:Eu3+ core–shell phosphors were prepared by the sol–gel process. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra as well as kinetic decays were used to characterize the resulting SiO2@Y2MoO6:Eu3+ core–shell phosphors. The XRD results demonstrated that the Y2MoO6:Eu3+ layers on the SiO2 spheres crystallized after being annealed at 700 °C and the crystallinity increased with raising the annealing temperature. The obtained core–shell phosphors have spherical shape with narrow size distribution (average size ca. 640 nm), non-agglomeration, and smooth surface. The thickness of the Y2MoO6:Eu3+ shells on the SiO2 cores could be easily tailored by varying the number of deposition cycles (70 nm for four deposition cycles). The Eu3+ shows a strong PL emission (dominated by 5D0–7F2 red emission at 614 nm) under the excitation of 347 nm UV light. The PL intensity of Eu3+ increases with increasing the annealing temperature and the number of coating cycles.

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