Photodegradation Of Methylene Blue Solution Research Articles

Furfural-induced hydrothermal synthesis of ZnO@C gemel hexagonal microrods with enhanced photocatalytic activity and stability.

Here we report the synthesis of ZnO@C coaxial gemel hexagonal microrods with a thin hydrothermal carbon (HTC) layer on their surface by a facile one-step hydrothermal method with furfural as the carbon precursor. The furfural has a unique dual role, which not only induces the nucleation of ZnO in the initial stage of hydrothermal process, but also forms a thin HTC layer deposited on the ZnO surface. The thickness of the surface HTC layer increases with the hydrothermal time until 16 h under the conditions adopted in the present study. It has been found that the HTC layer has resulted in a significant improvement in the photocatalytic activities and photostabilities of the ZnO@C microrods for the UV-irradiated photodegradation of methylene blue solution. The mechanism involved in the process is proposed and discussed in terms of the photodegradation scheme and the properties of the ZnO@C microrods.

Interfacial sol–gel processing for preparation of porous titania particles using a piezoelectric inkjet nozzle

The aim of the present work is to apply the liquid–liquid interfacial crystallization using a piezoelectric inkjet nozzle to the sol–gel processing. The instillation process was compared with the batch process to elucidate the effectiveness of the inkjet technique on the liquid–liquid interfacial sol–gel processing. The effect of frequency and water concentration in titanium tetraisopoxide (TTIP) solution on titania particle properties was investigated for sol–gel processing with a piezoelectric inkjet nozzle. Titania particles produced by each process were calcined at 500°C. The crystal structure, morphology, pore size distribution and specific surface area of titania particles were evaluated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen physisorption measurement. The photocatalytic activity of titania particles was evaluated by the photodegradation of methylene blue solution under UVC light irradiation.Monodispersed titania particles could be produced by instillation sol–gel processing of hexane using a piezoelectric inkjet nozzle. Titania particles prepared at 1500Hz were spherical while titania particles prepared at 1000Hz and 3000Hz were non-spherical. The number of particulate fracture increased with water concentration in TTIP solution. The inkjet nozzle-mediated instillation processing was found to be a promising way to create porous titania particles with a high photocatalytic activity.

Fast Synthesis of Ag<sub>3</sub>PO<sub>4</sub> Cube Microcrystals and its High Visible-Light-Driven Photocatalytic Activities

Ag3PO4 photocatalyst was successfully synthesized via a aqueous precipitation process using AgNO3, NH3·H2O and NH4H2PO4 as raw materials, and characterized by X-ray diffraction (XRD),solid-UV-Vis and FE-SEM techniques. Photodegradation of Methylene blue solution,Rhodamine B,was studied with Ag3PO4 under experiment light recourse of metal halide lamp . The XRD result showed that the sample Ag3PO4 synthesized in a high purity belongs to tetragonal. And the sample has a strong absorption between 200 nm and 400 nm analysized by UV-Vis. The photodegradation experiment showed that Methylene blue solutionRhodamine B was more easily photodegradated with Ag3PO4 and light recourse was metal halide lamp.

Fabrication and photocatalytic property of ZnO/SrTiO3 core/shell nanorod arrays

AbstractZnO/SrTiO3 core/shell nanorod arrays were fabricated by a facile two‐step method. ZnO nanorod arrays were first hydrothermally grown on Si substrate. Then, using liquid phase deposition method, SrTiO3 were deposited onto the ZnO nanorods to form core/shell nanorod structures. The morphologies and structures of the products were characterized by scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. The photocatalytic behavior of the nanorod arrays was also examined through the photodegradation of methylene blue solution under UV irradiation. It was found that the core/shell nanorod arrays with deposition time of 10 min showed higher photocatalytic activity than bare ZnO nanorod arrays. This enhancement was attributed to the efficient charge separation at the ZnO/SrTiO3 interface.

SnO2@CdS nanowire-quantum dots heterostructures: tailoring optical properties of SnO2 for enhanced photodetection and photocatalysis

Rationally designed SnO2@CdS nanowire-quantum dots (QDs) heterostructures were realized by a wet-chemical method via hydroxide cluster growth mechanism on high crystalline quality SnO2 nanowires, which were synthesized by a vapor transport method. The heterostructures showed enhanced photon harvesting capability and photodetection sensitivity at visible regime than that of wide band gap homogeneous SnO2 nanowires, as characterized by UV-Vis absorption and photoconductivity measurements. In addition, the SnO2@CdS nanowire-QDs heterostructures showed enhanced photocatalytic activity by more than 109% in a conceptual demonstration of photodegradation of methylene blue solution. Our results suggest that the SnO2@CdS nanowire-QDs heterostructures exhibit considerable promise for highly sensitive visible-light photodetectors and highly efficient photocatalysis.

Influence of annealing temperature on structure and photocatalytic activity of TiO2 thin films prepared by DC reactive magnetron sputtering method

Transparent TiO2 thin films were successfully prepared on high purity silica substrates by DC reactive magnetron sputtering method and annealed at different temperatures. The effects of the annealing temperature (300–600 °C) on crystalline structure, morphology, and photocatalytic activity of the TiO2 thin films were discussed. The photocatalytic activity of the films was evaluated by photodegradation of methylene blue solution. With increasing annealing temperature, the photocatalytic activity of the TiO2 thin films gradually increased because of the improvement of crystallization of anatase TiO2 thin films. At 500 °C, the TiO2 thin film shows the highest photocatalytic activity due to the improvement of crystallization of anatase TiO2 thin films. When the annealing temperature increases to 600 °C, the photocatalytic activity of thin film decreases owing to the formation of rutile phase and the decrease of surface area.

Hydrothermal Synthesis of Zinc Oxide Nanoparticle from Zinc-Dust Waste for Photocatalytic and Antibacterial Applications

ZnO nanoparticles were successfully synthesized by using zinc dust waste derived from hot-dip galvanizing process as a starting materials via simple hydrothermal method. The zinc dust powder was dissolved in nitric acid, adjusted pH with NaOH and hydrothermally treated at 120-170°C in an oven. The resultant products were characterized for phase, surface area and morphology by X-ray diffraction (XRD), Brunauer-Emmet-Taller (BET) and Scanning electron microscopy (SEM), respectively. Moreover, the photocatalytic activity was investigated by a photodegradation of methylene blue solution under black light irradiation. It was shown that crystallinity of pure ZnO phase, was influenced by solution and hydrothermal treatment temperature. The experimental results exhibited that the crystallinity of ZnO significantly affected its photocatalytic activity. The highest photocatlytic activity was obtained from powders with average crystallite size of 51 nm and surface area of 13.4 m2/g prepared under pH12 and hydrothermally treated at 170°C for 6 h. Moreover, the synthesized ZnO powders performed a good antibacterial activity evaluated using a colony count method with Escherichia coli under the dark condition.

Sol-gel template synthesis and photocatalytic behaviour of anatase titania nanoparticles

In this study, titania nanoparticles were successfully prepared by a sol-gel template method, employing cetyltrimethylammonium bromide (CTAB) and CaCO3 nanoparticles as templates. Titanium(IV) tetraisopropoxide and ethanol were used as a titanium precursor and alcoholic solvent, respectively. The obtained nanosized-titania was characterized by X-ray diffraction, transmission-electron microscopy, and N2 adsorption and desorption methods. The photocatalytic activity of titania was investigated from the photodegradation of methylene blue solution under UVC irradiation. The results indicated that the amount of anatase crystallites and pore characteristics were important factors influencing the degree of photocatalysis of titania nanoparticles. Highly crystalline anatase titania could be obtained through the controlled hydrolysis reaction rate and the formation of loose-packed titania nanoparticles, while high specific surface area could be achieved with a template method.

Photocatalytic Activity of Degussa P25 TiO2/Au Obtained Using Argon (Ar) and Nitrogen (N2) Plasma

Titania Degussa P25 powder was treated with Argon (Ar) and Nitrogen (N2) gas plasma inside of a closed homemade chamber system at 50 Pa of pressure. The electric discharge was generated applying an AC voltage (0–15,000 V) to a pair of aluminum electrodes. Two sets of samples were analyzed. In the first one, the plasma is applied directly on a layer of titania P25 that is spread out on top of one of the electrodes and, in the second one, a gold foil substrate is positioned between the titania powder and the electrode, named TiO2/Au. In the last sample, gold coated titania nanoparticles or clusters of gold are formed, changing the optical properties of the material. The evolution of the optical properties of the obtained samples was analized using UV–Vis diffuse reflectance. The spectra show a shift in the band gap and a broad band in P25/Au associated with the gold plasmonic band. Additionally, the photocatalytic activity was evaluated by monitoring the photodegradation of methylene blue solution (0.01 g/L), using UV–Vis absorption analysis in the range 250–850 nm. After the plasma is applied, the gold impregnation over the titania surface increases the photocatalytic activity.

Promoting Effect of MgO in the Photodegradation of Methylene Blue Over MgO/MWCNT/TiO2 Photocatalyst

For the present paper, we prepared MgO/MWCNT/<TEX>$TiO_2$</TEX> photocatalyst by using multi-walled carbon nanotubes (MWCNTs) pre-oxidized by m-chlorperbenzoic acid (MCPBA) with magnesium acetate tetrahydrate <TEX>$(Mg(CH_2COO)_2\cdot4H_2O)$</TEX> and titanium n-butoxide <TEX>$(Ti\{OC(CH_3)_3\}_4)$</TEX> as magnesium and titanium precursors. The prepared photocatalyst was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis. The decomposition of methylene blue (MB) solution was determined under irradiation of ultraviolet (UV) light. The XRD results show that the MgO/MWCNT/<TEX>$TiO_2$</TEX> photocatalyst have cubic MgO structure and anatase <TEX>$TiO_2$</TEX> structure. The porous structure and the <TEX>$TiO_2$</TEX> agglomerate coated on the MgO/MWCNT composite can be observed in SEM images. The Mg, O, Ti and C elements can be also observed in MgO/MWCNT/<TEX>$TiO_2$</TEX> photocatalyst from EDX results. The results of photodegradation of MB solution under UV light show that the concentration of MB solution decreased with an increase of UV irradiation time for all of the samples. Also, the MgO/MWCNT/<TEX>$TiO_2$</TEX> photocatalyst has the best photocatalytic activity among these samples. It can be considered that the MgO/MWCNT/<TEX>$TiO_2$</TEX> photocatalyst had a combined effect, the effect of MWCNT, which could absorb UV light to create photoinduced electrons <TEX>$(e^-)$</TEX>, and the electron trapping effect of MgO, which resulted in an increase of the photocatalytic activity of <TEX>$TiO_2$</TEX>.

가시광선과 UV광선에 의한 Fe 처리된 AC/TiO2복합체의 광분해활성

FAT복합체는 TOS (<TEX>$TiOSO_4{\cdot}xH_2O$</TEX>)를 사용하여 솔-겔 방법으로 제조한다. 시료들은 SEM, 비표면적, XRD 및 EDX를 사용하여 분석하였다. SEM결과로서 Fe 와 <TEX>$TiO_2$</TEX> 입자가 AC 표면에 분포하고 있다. XRD 결과에서 Fe-AC/<TEX>$TiO_2$</TEX> 복합체는 다 anatase결정상을 하고 있다. 그리고 EDX 결과에서 C, O, Ti 및 Fe 원소가 Fe-AC/<TEX>$TiO_2$</TEX> 복합체에 다 존재하고 있다. 복합체의 광촉매 활성은 가시광선과 UV광선을 사용하고 메틸렌불루(MB)의 분해 효과에 의해 측정한다. Fe-AC/<TEX>$TiO_2$</TEX> 복합체는 강한 가시광선 조사에서 우수한 광촉매 효과가 나타난다. AC/<TEX>$TiO_2$</TEX> 복합체에 있는 소량 존재하는 Fe 원소가 그들의 광촉매 활성을 강화할 수 있다. FAT compounds photocatalysts were prepared with <TEX>$TiOSO_4{\cdot}xH_2O$</TEX> (TOS) by a sol-gel method. The samples were characterized by scanning electron microscopy (SEM), BET specific surface area, X-ray diffraction analysis (XRD) and energy dispersive X-ray spectroscopy (EDX). The SEM results showed that ferric compounds and titanium dioxide were fixed onto the AC surfaces. The XRD results showed that Fe-AC/<TEX>$TiO_2$</TEX> composites mostly contained anatase phase. EDX showed the presence of C, O, and Ti with Fe peaks in all samples. The photocatalytic activities were evaluated by the photocatalytic oxidation of methylene blue (MB) solution, via compare photodegradation of MB solution under visible light and UV light separately. Fe-AC/<TEX>$TiO_2$</TEX> composites had an excellent photocatalytic under strong visible light irradiation. A small amount of Fe ions in AC/<TEX>$TiO_2$</TEX> particles could obviously enhance their photocatalytic activity.

Co-ACFs/TiO2복합체의 제조 및 그의 메틸렌블루의 광분해

Cobalt-loaded activated carbon fibers (ACFs) supported titanium dioxide (TiO2) photocatalyst was developed by sol-gel method. The Co-ACFs/TiO2 photocatalyst were characterized by scanning electron microscope (SEM), X-ray diffraction patterns (XRD), energy dispersive X-ray analysis (EDX) and UV-vis absorption spectroscopy. Decomposition efficiency of methylene blue (MB) solution by Co-ACFs/TiO2 photocatalyst reached almost 100% under 300 min reaction. The MB molecules in the bulk solutions were supposed to be condensed around TiO2 particles by adsorption of ACFs. Therefore, the photocatalyst possesses the combined effect of adsorption by activated carbon fibers and photocatalytic reactivity of TiO2 on MB degradation. Due to the cobalt has electron transition effece, thus improved the photodegradation of MB solution.