Decomposition Of Methyl Orange Solution Research Articles

Фотокаталитическое разложение растворов метилового оранжевого на поверхности нанопористых слоев меди, серебра и их йодидов

The efficiency of photocatalytic decomposition of methyl orange solutions on the surface of nanoporous layers of copper, silver and their iodides has been studied. It is shows that nanoporous layers on metal substrates have two absorption bands: they absorb radiation in the UV and Vis spectral range. The process of decomposition of methyl orange molecules on the surface of metal-semiconductor nanostructures Cu-CuI and Ag-AgI occurs under the action of UV and Vis irradiation. While transparency of the methyl orange solution increases.

Mixed oxides on rutile TiO2(011): Cr2O3 and Cu2O

The authors investigate the formation of ultrathin oxides on rutile TiO2(011) single crystal surfaces by scanning tunneling microscopy and photoemission techniques in view of the role of substrate orientation for the formation of special oxide species and films. The authors observe that the (011) orientation of rutile facilitates the stabilization of ordered atomic-scale Cu+ species under weak oxidizing conditions. In contrast, clustering is observed on the (110) surface prepared under the same conditions. For chromium deposition in an oxidizing environment growth of an epitaxial but twinned Cr2O3 film with (1-102) orientation is observed. High crystalline order is maintained to the ultrathin monolayer limit. X-ray photoelectron spectroscopy suggests some diffusion of Ti3+ species into Cr2O3 films while the surface of Cr2O3 appears to be reducible by vacuum annealing to ∼300 °C. An increased photocatalytic activity for decomposition of methyl orange solution is measured for TiO2(011) surfaces modified with a submonolayer film of chromia while for thicker Cr2O3 films the photocatalytic activity decreases again.

Anatase-Titania Templated by Nanofibrillated Cellulose and Photocatalytic Degradation for Methyl Orange

In this work, novel titania (TiO2) nanoparticles were designed as a high performance photocatalyst. It was obtained by a simple method of dispersing nanofibrillated cellulose (NFC) onto the surface of titanium tetrachloride (TiCl4), inducing crystallization and removing NFC templates. Under UV light irradiation, The TiO2 nanoparticles displayed excellent photocatalytic activity for the decomposition of methyl orange solution. It was found that TiO2 after calcination had a more efficiency than that before calcination. The optimum calcination temperature for the removal of NFC templates was 300 °C. Methyl orange solution had been remarkably degraded by TiO2 nanoparticles when the mass ratio of TiCl4 and NFC was 12:1. These results indicate that the TiO2 nanopartilces can be easily applied in the field of wastewater treatment.

Preparation of Zn2+–Ni2+–Fe3+–CO32−LDHs and study of photocatalytic activities for decomposition of Methyl Orange solution

New type photocatalytic materials of Zn2+–Ni2+–Fe3+–CO32−LDHs were prepared by complexing agent-assisted homogeneous precipitation technique and Zn(NO3)2·6H2O, Ni(NO3)·6H2O, Fe(NO3)3·9H2O used as raw materials in the case of molar ratio of Zn2+/Ni2+/Fe3+ = 1:6:2. Zn2+–Ni2+–Fe3+–CO32−LDHs having a specific surface area of 96.5 m2/g. The structure and catalytic properties of the material were systematically studied. The experimental results show that the Zn2+–Ni2+–Fe3+–CO32−LDHs has a higher adsorption performance and lower band gap which make it an excellent catalyst for reducing the degradation of the methyl orange. Study on the process of photocatalytic reaction shows that Methyl Orange was adsorbed to the layer of Zn2+–Ni2+–Fe3+–CO32−LDHs, and then it was photodecomposed to inorganic molecules and ions by Zn2+, Ni2+, and Fe3+ on the surface of Zn2+–Ni2+–Fe3+–CO32−LDHs.

Photocatalytic activity of anatase and rutile TiO2 epitaxial thin film grown by pulsed laser deposition

Epitaxial rutile-TiO2(011) and anatase-TiO2(001) films have been grown by pulsed laser deposition on Al2O3(1¯102) and LaAlO3(100), respectively. For low growth rates of ~0.0012nm/s and growth temperatures of 600°C high quality films are obtained. In particular the anatase films exhibit 100nm wide flat terraces for 10–15nm film thickness. Atomic steps of both ~0.25 and ~0.5nm are measured, suggesting the existence of two different terminations, although only a 4×1 reconstruction is observed in reflection high-energy electron diffraction. The rutile films exhibit coherent twin domain boundaries, which is likely the reason for smaller terrace sizes compared to anatase films. Photocatalytic activity of the films is measured by decomposition of methyl orange solution under UV-irradiation. The anatase films are about twice as active as the rutile films. For both films the activity does not change significantly for films of 10nm and thicker. For rutile films the activity is also compared to that of single crystal rutile TiO2(011) samples. Both rutile-films and single crystals exhibit very similar activity, indicating the good quality of the films. Post-growth annealing of the films in air at 600°C decreases the photocatalytic activity of the films. On the other hand, reduction of thin films by vacuum annealing to 800°C does not change the photocatalytic activity of the films significantly compared to the as grown films. This is in contrast to single crystal rutile samples whose photocatalytic activity for the decomposition of methyl orange almost doubles after reduction by high-temperature annealing in vacuum compared to the stoichiometric bulk-samples. The differences between films and bulk samples may hint differences in defect formation due to the substrate interface.

Effect of Zn and Ti mole ratio on microstructure and photocatalytic properties of magnetron sputtered TiO2–ZnO heterogeneous composite film

Series of TiO2–ZnO heterojunction composite films with different n(Zn)/n(Ti) ratios were prepared by UDP450 magnetron sputter ion plating equipment, and the mole ratio of Zn to Ti was controlled by adjusting the current values of sputtering target. The effects of n(Zn)/n(Ti) on the microstructures of TiO2–ZnO films were investigated by SEM, AFM, Raman and XPS, and their photocatalytic decomposition of methyl orange solutions was evaluated. The results show that an increase in n(Zn)/n(Ti) typically results in a decrease in the grain size of composite films firstly and then an increase of grain size, while an increase in n(Zn)/n(Ti) leads to an increase in film roughness firstly and then a decrease in film roughness. Both grain size and roughness of TiO2–ZnO films reach the maximum and minimum at n(Zn)/n(Ti) of 1/9.3, respectively. The n(Zn)/n(Ti) shows little effect on the valences of Zn and Ti elements, which mainly exist in the form of TiO2 and ZnO phases. The n(Zn)/n(Ti) has influence on the amount of anatase/rutile TiO2 heterojunction in the film. With increase of the n(Zn)/n(Ti), the absorption intensity of the composite film increases and the absorption region extends to 450 nm, which is redshifted as much as 150 nm in comparison with the pure TiO2 films. However, the photocatalytic abilities of heterogeneous composite films do not depend on the n(Zn)/n(Ti) but rather on the microstructures of the TiO2–ZnO composite films. Degradation rate of the film reaches the maximum and the photocatalytic decomposition of pollutants works best when n(Zn)/n(Ti)=1:9.3.

A novel composite photocatalyst based on in situ growth of ultrathin tungsten oxide nanowires on graphene oxide sheets

Graphene oxide sheets were initially prepared by a modified pressurized oxidation method. Through a one-pot solvothermal route, a novel composite photocatalyst based on in situ growth of ultrathin W18O49 nanowires with diameters of 2–3 nm on graphene oxide sheets was then successfully fabricated. The as-prepared graphene oxide sheets and W18O49–reduced graphene oxide composite have been systematically characterized by combined techniques of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Raman microscopy, X-ray photoelectron spectrometry, and UV-vis diffuse reflectance spectroscopy. Compared to the W18O49 nanoflowers prepared in the absence of graphene oxide sheets, the W18O49–reduced graphene oxide composite exhibited significantly enhanced photocatalytic properties for the decomposition of methyl orange solution and for the growth inhibition of V. natriegens under full spectrum light, which is mainly due to the strong coupling interaction between the W18O49 nanowires and the reduced graphene oxide sheets. The present solvothermal process simultaneously enables the reduction of graphene oxide and the formation of W18O49, making it suitable for the preparation of other graphene-based composites.

Influences of working pressure on properties for TiO 2 films deposited by DC pulse magnetron sputtering

TiO 2 films were deposited at room temperature by DC pulse magnetron sputtering system. The crystalline structures, morphological features and photocatalytic activity of TiO 2 films were systematically investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and ultraviolet spectrophotometer, respectively. The results indicated that working pressure was the key deposition parameter influencing the TiO 2 film phase composition at room temperature, which directly affected its photocatalytic activity. With increasing working pressure, the target self-bias decreases monotonously. Therefore, low temperature TiO 2 phase (anatase) could be deposited with high working pressure. The anatase TiO 2 films deposited with 1.4 Pa working pressure displayed the highest photocatalytic activity by the decomposition of Methyl Orange solution, which the degradation rate reached the maximum (35%) after irradiation by ultraviolet light for 1 h.

Photocatalytic Degradation of Methyl Orange: Influence of H2O2 in the TiO2-Based System

The purpose of this study was to investigate the photocatalytic oxidation of a reactive azo dye. The photocatalytic activity of the TiO2 was studied using a reactor equipped with UV-A sources, with maximum emission at 365 nm. The photocatalytic activity of the TiO2 powder (99.9% anatase) and thin films has been measured through the decomposition of methyl orange solutions. The thin film was prepared by doctor blade and spray pyrolysis deposition (SPD). The TiO2 suspensions were prepared at 1 g/L concentration, and the initial methyl orange concentration was fixed at 7.8125 mg/L. The influence of the TiO2 (powder or thin films) and/or O2 and H2O2 on the photobleaching rate, was tested under different experiments, at pH = 5. Thin films (doctor blade) of TiO2 formed of mezo-sized aggregates formed of nanosized anatase crystallites show better photobleaching efficiency than thin film (SPD) due to their large internal surface. The rate is even higher in H2O2 compared to oxygen environment.