scholarly journals Design and preliminary test of a fluidised bed photoreactor for ethylene oxidation on mesoporous mixed SiO2/TiO2 nanocomposites under UV-A illumination

2014 ◽  
Vol 45 (4) ◽  
pp. 146 ◽  
Author(s):  
Maria Lucia V. De Chiara ◽  
Maria Luisa Amodio ◽  
Francesco Scura ◽  
Luigina Spremulli ◽  
Giancarlo Colelli
Keyword(s):  
Photocatalytic Activity ◽  
Uv Light ◽  
Light Exposure ◽  
Preliminary Test ◽  
Ethylene Oxidation ◽  
Fluidised Bed ◽  
Ethylene Concentration ◽  
Postharvest Handling ◽  
Ethylene Action ◽  
Fresh Products

Ethylene (C<sub>2</sub>H<sub>4</sub>) is a plant hormone that has numerous effects on many horticultural and ornamental crops. It accelerates senescence, stimulates chlorophyll loss, enhances excessive softening, promotes discoloration and browning during storage of fresh produce. Among the techniques used to remove or inhibit ethylene action during postharvest handling of fresh products (potassium-based system, high temperature catalytic oxidation, inhibition of ethylene receptors), the use of titanium oxide (TiO<sub>2</sub>)-based materials with photocatalytic activity under ultraviolet (UV) light is one of the most promising. A fluidised-bed photoreactor (FBP) was designed to decompose ethylene in the storage room atmosphere, and the relative prototype was manufactured. Since TiO<sub>2</sub> powder alone is not suitable for use within a fluidised bed, preliminary tests to select the best support were performed. Alumina microspheres showed a good fluidisation behavior; its functionality was tested with different kind of support material and actual photocatalytic activity was tested using SiO<sub>2</sub>/TiO<sub>2</sub>-coated alumina microspheres. A reduction of approximately 72% of ethylene concentration in the tested 40 ppm ethylene gas mixture was observed after 4.5 h of 36W UV light exposure. FBP resulted to be suitable to avoid the detrimental presence of C<sub>2</sub>H<sub>4</sub> in the atmosphere surrounding fresh products within cold storage rooms.

scholarly journals Stable CuCrO2 nanoparticles - ZnO fibres p-n heterostructure system for effective photocatalytic activity

2019 ◽  
Vol 13 (2) ◽  
pp. 189-201 ◽  
Author(s):  
Elif Baylan ◽  
Hasan Akyildiz ◽  
Ozlem Yildirim
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Uv Light ◽  
Light Exposure ◽  
Band Gap Energy ◽  
Blue Dye ◽  
Nanoparticle Dispersion ◽  
K Value ◽  
Composite Photocatalyst ◽  
Visible Light Active

Heterostructured photocatalysts were fabricated by coupling electrospun n-type ZnO fibres and hydrothermally derived p-type CuCrO2 nanoparticles. The effect of the amount of CuCrO2 nanoparticles on the photocatalytic activity of the heterostructured photocatalyst was systematically investigated. The formation of the heterojunctions between the two semiconductors was revealed via detailed XRD, XPS, TEM and optical property measurements. The experimental results indicated that the optimal CuCrO2 amount in the composite photocatalyst was 1.0wt.% due to the optimum doping and surface coverage, higher absorption onset edge, larger absorption intensity and optimum band gap energy. This composite photocatalyst, fabricated by drop casting of CuCrO2 nanoparticle dispersion on ZnO fibres, displayed 30% higher rate constant (k) value compared to the pure ZnO fibres in the degradation of methylene blue dye molecules and reached 93.4% decomposition in 1 h under UV-visible light exposure. The obtained results are highly encouraging in comparison to only UV/light active p-n heterostructured photocatalysts previously reported in literature. Therefore, we believe that the proposed approach here opened the way for simple synthesis of highly-efficient visible light active heterostructured semiconductor photocatalyst systems.

scholarly journals Electrical behavior and enhanced photocatalytic activity of (Ag, Ni) co-doped ZnO nanoparticles synthesized from co-precipitation technique

2020 ◽  
Vol 81 (6) ◽  
pp. 1296-1307
Author(s):  
R. Jeyachitra ◽  
S. Kalpana ◽  
T. S. Senthil ◽  
Misook Kang
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Zno Nanoparticles ◽  
Uv Light ◽  
Light Exposure ◽  
Precipitation Method ◽  
Zno Nps ◽  
Transmission Electron ◽  
Doped Zno ◽  
Co Precipitation

Abstract Methylene blue (MB) dye is the most common harmful, toxic, and non-biodegradable effluent produced by the textile industries. The present study investigates the effect of zinc oxide (ZnO) nanoparticles (NPs) and Ag–Ni doped ZnO NPs on the performance of photocatalytic degradation of MB dye. Pure ZnO and Ag–Ni doped ZnO NPs are synthesized using the co-precipitation method. The crystalline nature and surface morphology of the synthesized pure ZnO and Ag–Ni doped ZnO NPs was characterized by powder X-ray diffraction, scanning electron microscopy (SEM), and high resolution transmission electron microscopy (HRTEM) analysis. The presence of spherical-like morphologies was confirmed from SEM and HRTEM analysis. The presence of Ni–O and Zn–O bands in the synthesized materials was found by Fourier transform infrared (FTIR) spectroscopy analysis. The MB dye was degraded under UV-light exposure in various pH conditions. The Ag (0.02%)–Ni doped ZnO NPs exhibits highest photocatalytic activity of 77% under pH 4.

Some Influencing Factors on Photocatalytic Activity of TiO2 Film Prepared Using Sol-Gel Method

2012 ◽  
Vol 433-440 ◽  
pp. 362-366 ◽  
Author(s):  
Wen Jie Zhang ◽  
Qian Li ◽  
Wen Bin Liu
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Flow Rate ◽  
Glass Substrate ◽  
Uv Light ◽  
Light Exposure ◽  
Air Flow ◽  
Sol Gel ◽  
Air Flow Rate ◽  
Degradation Rates

Subscript text TiO2film was deposited on glass substrate by a sol-gel process. The influences of the SiO2layer, distance between lamp and solution, and air flow rate were investigated. Methyl orange can be hardly degraded under UV light exposure alone. The adsorption rate of methyl orange on TiO2film is negative after 25 min of stirring. Although distance between the lamp and the solution varies from 5.5 cm to 7.5 cm, the degradation rates decline slightly. There is nearly no influence of air flow rate on the entire degradation ability of the photocatalyst. SiO2film coated on microscope glass slide has no photocatalytic activity under UV irradiation. In prior to deposit TiO2film onto the surface of the glass substrate, a SiO2thin layer is coated. The results indicate that the TiO2film with SiO2layer has much better photocatalytic activity that the film without SiO2layer.

Tuning the Photocatalytic Performance of Plasmonic Nanocomposites (ZnO/Aux) Driven in Visible Light

2019 ◽  
Vol 8 (1) ◽  
pp. 56-61
Author(s):  
Aneeya K. Samantara ◽  
Debasrita Dash ◽  
Dipti L. Bhuyan ◽  
Namita Dalai ◽  
Bijayalaxmi Jena
Keyword(s):  
Electron Transfer ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Transfer Rate ◽  
Photocatalytic Performance ◽  
Light Exposure ◽  
Au Nanoparticle ◽  
Electron Transfer Rate ◽  
Au Nps ◽  
Zno Nanostructure

: In this article, we explored the possibility of controlling the reactivity of ZnO nanostructures by modifying its surface with gold nanoparticles (Au NPs). By varying the concentration of Au with different wt% (x = 0.01, 0.05, 0.08, 1 and 2), we have synthesized a series of (ZnO/Aux) nanocomposites (NCs). A thorough investigation of the photocatalytic performance of different wt% of Au NPs on ZnO nanosurface has been carried out. It was observed that ZnO/Au0.08 nanocomposite showed the highest photocatalytic activity among all concentrations of Au on the ZnO surface, which degrades the dye concentration within 2 minutes of visible light exposure. It was further revealed that with an increase in the size of plasmonic nanoparticles beyond 0.08%, the accessible surface area of the Au nanoparticle decreases. The photon absorption capacity of Au nanoparticle decreases beyond 0.08% resulting in a decrease in electron transfer rate from Au to ZnO and a decrease of photocatalytic activity. Background: Due to the industrialization process, most of the toxic materials go into the water bodies, affecting the water and our ecological system. The conventional techniques to remove dyes are expensive and inefficient. Recently, heterogeneous semiconductor materials like TiO2 and ZnO have been regarded as potential candidates for the removal of dye from the water system. Objective: To investigate the photocatalytic performance of different wt% of Au NPs on ZnO nanosurface and the effect of the size of Au NPs for photocatalytic performance in the degradation process. Methods: A facile microwave method has been adopted for the synthesis of ZnO nanostructure followed by a reduction of gold salt in the presence of ZnO nanostructure to form the composite. Results: ZnO/Au0.08 nanocomposite showed the highest photocatalytic activity which degrades the dye concentration within 2 minutes of visible light exposure. The schematic mechanism of electron transfer rate was discussed. Conclusion: Raspberry shaped ZnO nanoparticles modified with different percentages of Au NPs showed good photocatalytic behavior in the degradation of dye molecules. The synergetic effect of unique morphology of ZnO and well anchored Au nanostructures plays a crucial role.

scholarly journals Stability and ocular biodistribution of topically administered PLGA nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sean Swetledge ◽  
Renee Carter ◽  
Rhett Stout ◽  
Carlos E. Astete ◽  
Jangwook P. Jung ◽  
...  
Keyword(s):  
Uv Light ◽  
Light Exposure ◽  
Polymeric Nanoparticles ◽  
Plga Nanoparticles ◽  
Eye Disease ◽  
Control Group ◽  
Eye Tissues ◽  
Nanoparticle Morphology ◽  
The Stability

AbstractPolymeric nanoparticles have been investigated as potential delivery systems for therapeutic compounds to address many ailments including eye disease. The stability and spatiotemporal distribution of polymeric nanoparticles in the eye are important regarding the practical applicability and efficacy of the delivery system in treating eye disease. We selected poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with lutein, a carotenoid antioxidant associated with eye health, as our model ophthalmic nanodelivery system and evaluated its stability when suspended in various conditions involving temperature and light exposure. We also assessed the ocular biodistribution of the fluorescently labeled nanoparticle vehicle when administered topically. Lutein-loaded nanoparticles were stable in suspension when stored at 4 °C with only 26% lutein release and no significant lutein decay or changes in nanoparticle morphology. When stored at 25 °C and 37 °C, these NPs showed signs of bulk degradation, had significant lutein decay compared to 4 °C, and released over 40% lutein after 5 weeks in suspension. Lutein-loaded nanoparticles were also more resistant to photodegradation compared to free lutein when exposed to ultraviolet (UV) light, decaying approximately 5 times slower. When applied topically in vivo, Cy5-labled nanoparticles showed high uptake in exterior eye tissues including the cornea, episcleral tissue, and sclera. The choroid was the only inner eye tissue that was significantly higher than the control group. Decreased fluorescence in all exterior eye tissues and the choroid at 1 h compared to 30 min indicated rapid elimination of nanoparticles from the eye.

Photocatalytic activity of polyaniline and neutral polyaniline for degradation of methylene blue and malachite green dyes under UV Light

2021 ◽  
Vol 78 (5) ◽  
pp. 2849-2865
Author(s):  
Bircan Haspulat Taymaz ◽  
Recep Taş ◽  
Handan Kamış ◽  
Muzaffer Can
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Malachite Green ◽  
Uv Light
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