Decomposition Of MB Research Articles

Facile synthesis, structural, optical and photocatalytic properties of mesoporous Ag2O/TiO2 nanoheterojunctions

We have successfully synthesized ball-like mesoporous Ag2O/TiO2 nanohybrids with extremely high surface area (~2779 m2/g) and excellent photodegradation activity by a facile wet chemical method. The synthesis involves CTAB-assisted self-assembly of TiO2 nanocrystals and Ag nanoparticles into ball-like mesoporous Ag2O/TiO2 hybrid nanostructures. Raman spectroscopy, transmission electron microscopy, BET surface area analysis and X-ray diffraction were employed to determine the structural characteristics of the synthesized Ag2O/TiO2 nanohybrids, while the optical behaviour was explored by optical absorption spectroscopy and photoluminescence spectroscopy. A growth mechanism underlying the formation of ball-like mesoporous Ag2O/TiO2 nanohybrids is tentatively proposed. The photodegradation activity of mesoporous Ag2O/TiO2 nanohybrids was studied by evaluating sunlight induced photodegradation of RhB and MB dyes and 4-nitrophenol. Mesoporous Ag2O/TiO2 nanohybrids exhibited excellent photodegradation activity for the decomposition of RhB, MB and 4-nitrophenol. The observed excellent photodegradation activity of mesoporous Ag2O/TiO2 nanohybrids is ascribed to the combined effects of their large surface area leading to efficient adsorption of pollutants, improved solar light harvesting and efficient separation of photoinduced electron-hole pairs due to formation of Ag2O/TiO2 nanoheterojunctions.

Fabrication of Au-CuO hybrid plasmonic nanostructured thin films with enhanced photocatalytic activity

Thin films of Au-CuO plasmonic nanohybrids were fabricated by simple thermal evaporation. SEM and XRD investigations unveiled the impact of annealing on the structural properties and morphology of the synthesized Au-CuO hybrid thin film. Au nanoparticle decoration onto CuO thin film significantly altered the photocatalytic activity, structural and optical properties of CuO thin film. The as-prepared Au-CuO nanostructured hybrid plasmonic thin film showed improved photocatalytic efficiency for decomposition of MG and MB than pristine CuO and annealed Au-CuO thin film samples. The improved photocatalytic efficiency of Au-CuO hybrid nanostructured thin film is attributed to reduction in the recombination of charge carriers in CuO nanostructures and improvement in light utilization capability due to attachment of Au nanoparticles on nanostructured CuO thin film. Cracks in Au-CuO nanohybrid thin film facilitated enhanced adsorption of dye molecules and played an essential role in improving the photocatalytic efficiency.

Preparation of novel ternary TiO2 QDs/CDs/AgI nanocomposites with superior visible-light induced photocatalytic activity

In this research, visible-light-induced TiO2 QDs/CDs/AgI photocatalysts were synthesized by simple refluxing strategy. Various instruments such as TEM, HRTEM, FESEM, EDX, XRD, XPS, PL, EIS, photocurrent, FT-IR, BET, UV–vis DRS, and Mott–Sckottky were exploited to investigate their characteristics. Photocatalytic abilities of the as-obtained samples were assessed by decomposition of MB, fuchsine, RhB, and phenol upon visible light. The optimum TiO2 QDs/CDs/AgI (30%) nanocomposite completely degraded RhB after 30 min. This enhancement is about 77, 6, and 2.7 times as premiere as those of the bare TiO2, TiO2 QDs, and TiO2 QDs/CDs (0.25 mL) samples, respectively. These increments of photocatalytic ability is credited to the more generation and transfer of e–/h+ pairs among TiO2 QDs, CDs, and AgI counterparts and improved textural features. The higher photocatalytic activity and long-term stability results proved that the TiO2 QDs/CDs/AgI (30%) nanocomposite could be an auspicious candidate for the elimination of different organic contaminants in the ecosystem. Moreover, a reasonable mechanism for the photodegradation of pollutants was also proposed.

Application of phosphorescent material in activation of N:Cu:TiO2 photocatalyst as antibacterial and dye removal agent from solid surfaces used in hospitals

In this study, capability of co-doped TiO2 NPs photocatalyst to remove MB as a volatile organic compound sample and disinfect the bacteria existence on solid surfaces in hospitals is investigated. Unfortunately, cleaning the interior environment of the public buildings such as hospitals with detergents puts the human health and the environment at risk, most importantly resulting in the loss of time and cost. Photocatalytic oxidation (like TiO2) is among the methods used to disinfect bacterial cells and degrade VOCs. TiO2 and its derivatives can be excited by UV and visible light. The main drawback of this photocatalyst is its inactivity in the absence of light irradiation. In the current study, TiO2 NPs were doped with Cu and N ions and called composite-A. Then, synthesized photocatalyst was mixed with phosphorescent material and called composite-B. Both composites were coated on few tiles surface. The tile coated with composite-A was placed under a LED lamp, while the latter was placed in a dark place. Both nanocomposites were characterized by using analytical techniques including XRD, FT-IR, SEM, DRS, and UV-VIS. Moreover, bacterial degradation and MB decomposition tests were done. The crystallite size was calculated to be 120.5 nm. Besides, SEM images confirmed that the particles size was in range between 10–60 nm. The MB degradation efficiency for composite-A sample was ˜33% while for composite-B was ˜13%, due to the low emission of phosphorescence and lack of oxygen. The antibacterial result indicated significant numbers of bacterial colonies growth on the tile circumference surface.

Revisiting the problem of using methylene blue as a model pollutant in photocatalysis: The case of InVO4/BiVO4 composites

Evaluation of photocatalytic activity towards oxidative degradation of organic pollutants is of crucial importance in heterogeneous photocatalysis. In this study, we address the problem of using a visible-light absorbing dye, methylene blue, as a model pollutant in photocatalytic investigations based on experiments using visible light-responsive InVO4/BiVO4 composite photocatalyts. We found that InVO4/BiVO4 composites exhibit photoactivity in oxidative decomposition of MB under visible light, but no degradation was found in case of other dyes (e.g., rhodamine B or methyl orange) or transparent organic pollutants (e.g., 4-chlorophenol and diethyl phthalate). Detailed mechanistic studies demonstrate that the mechanism of photocatalytic degradation of MB depends on excitation light energy. If the InVO4/BiVO4 composite is excited exclusively (400 nm < λ < 500 nm), direct photocatalytic oxidation of MB occurs. Surprisingly, wavelength-resolved photocurrent measurements indicated that the degradation of MB under long-wavelength irradiation (λ > 560 nm), where MB can be excited but the InVO4/BiVO4 photocatalyst itself cannot, is not caused by the indirect mechanism involving sensitization and injection from the MB excited state to the conduction band of the photocatalyst. Instead, in this range the oxidation of MB is initiated by singlet oxygen formed via energy transfer from the excited MB to triplet oxygen, a degradation mechanism hitherto neglected in the literature. More generally, our study highlights the very peculiar photochemistry of MB in heterogeneous photocatalysis, and leads to the conclusion that MB is completely unsuitable for photocatalytic testing under visible light, and its use as a model pollutant should be definitely discouraged.

Fabrication and Characterization of Y2Ti2O7 Powder and Thick Film by Chemical Processing

Y2Ti2O7 nanoparticles (0.3 mol%) have been successfully synthesized by the co-precipitation process. The samples, adjusted to pH7 with ammonia solution as catalyst and calcined at 700~900 °C, exhibit very fine particles with close to spherical shape and average size of 10-30 nm. It was possible to control the size of the synthesized Y2Ti2O7 particles by manipulating the conditions. The Y2Ti2O7 nanoparticles were coated on a glass substrate by a dipping coating process with inorganic binder. The Y2Ti2O7 solution coated on the glass substrate had excellent adhesion of 5B; pencil hardness test results indicated an excellent hardness of 6H. The thickness of the thick film was about 30 μm. Decomposition of MB on the Y2Ti2O7 thin film shows that the photocatalytic properties were excellent.

Facile one-step in-situ synthesis of type-II CeO2/CeF3 composite with tunable morphology and photocatalytic activity

Ce-based materials have gained considerable prominence in catalysis as a type of the most valuable material for various applications ranging from automotive emission control to CO2 and water splitting. We here report a novel type-II CeO2/CeF3 composite, composed of two paradigms of Ce-based binary compounds, prepared by a facile one-step in-situ hydrothermal method, and explore its potential as a photocatalyst for solar energy conversion. Primarily, the morphologies, particle size and microstructures of CeO2/CeF3 composite can be modulated by the volume ratio of ethanol to water in the precursor solution. The photocatalytic activities firstly increase to a maximum and then decrease with the increased amount of ethanol. The hybrid CeO2/CeF3 particles with large size and polyhedron morphology exhibit superior photocatalytic activity, having a high rate constant k of MB decomposition about 7.6 times faster than that of the lowest one. A multiple synergetic mechanism in CeO2/CeF3 composite, which is featured by obvious promoted separation of photogenerated electrons and holes at the type-II heterojunction interfaces and in particular between the different facets of microcrystals, and the highly reactive facets exposed, has been proposed to account for its distinguished photocatalytic activity. This work provides some new insights for the synthesis and optimization of novel rare earth Ce-based composite photocatalyst with high photocatalytic performance.

Origin of enhanced photocatalytic activity of F-doped CeO2 nanocubes

CeO2 nanoparticles are synthesized using a low-temperature solution combustion method and subsequent heat treatment in air. It is found that F-doping leads to smaller particle size and the formation of CeO2 nanocubes with higher percentage of reactive facets exposed. The band gap is estimated to be 3.16eV and 2.88eV, for pure CeO2 and fluorine doped CeO2 (F-doped CeO2) nanocubes, respectively. The synthesized F-doped CeO2 nanocubes exhibit much higher photocatalytic activities than commercial TiO2 and spherical CeO2 for the degradation of MB dye under UV and visible light irradiation. The apparent reaction rate constant k of MB decomposition over the optimized F-doped CeO2 nanocubes is 9.5 times higher than that of pure CeO2 and 2.2 times higher than that of commercial TiO2. The enhanced photocatalytic activity of F-doped CeO2 nanocubes originates from the fact that F-doping induces the small size, the highly reactive facets exposed, the intense absorption in the UV–vis range and the narrowing of the band gap. This research provides some new insights for the synthesis of the doping of the foreign atoms into photocatalyst with controlled morphology and enhanced photocatalytic activity.

Green fabrication of magnetic recoverable graphene/MnFe2O4hybrids for efficient decomposition of methylene blue and the Mn/Fe redox synergetic mechanism

Magnetic RGO/MnFe2O4hybrids were fabricated in a green manner for significant MB decomposition with an experimentally proven Fe/Mn redox couple synergetic catalytic mechanism.

Experimental and theoretical study on thermal decomposition of methyl butanoate behind reflected shock waves

The rate coefficients for total decomposition of MB in the temperature range of 1229–1427 K, were reported.

Green synthesis of bi-component Mn3O4–MnO2 nanorods and enhanced catalytic properties

Bi-component Mn3O4–MnO2 nanorods with lengths of up to 30μm are synthesized using a simple hydrothermal method in the absence of templates. Samples were characterized by FE-SEM, HR-TEM, XRD, XPS, and N2 adsorption–desorption. The results indicate that the Mn3O4–MnO2 and Mn5O8 samples with various morphologies can be easily obtained via modulating Cl− ions and glucose contents. Compared with that of the Mn5O8 samples, the bi-component Mn3O4–MnO2 nanorods exhibited higher catalytic properties for oxidative decomposition of MB owing to its adjustable valence state and oxygen content.

Three Cd(II) coordination polymers based on rigid 2,6-bis(3-(pyrid-3-yl)-1,2,4-triazolyl)pyridine ligand: Syntheses, crystal structures, and photocatalytic properties

Three Cd(II) coordination polymers, namely, {[Cd2(bptp)2(H2O)4]·3H2O}n (1), {[Cd2(Hbptp)(BTC)(H2O)]·4H2O}n (2) and {[Cd2(H2bptp)(BTEC)]·H2O}n (3) (1,3,5-H3BTC=1,3,5-benzenetricarboxylic acid and H4BTEC=1,2,4,5-benzenetetracarboxylic acid), have been successfully isolated by employing the rigid N-heterocyclic ligand 2,6-bis(3-(pyrid-3-yl)-1,2,4-triazolyl)pyridine (H2bptp) and different aromatic polycarboxylates. Complex 1 performs a helical chain structure, which is extended into 3D supermolecular framework due to its strong hydrogen bonding interactions. 2 demonstrates a binodal 3,4-connected 2D grid with the point symbol of (42·62·8)(42·6), while complex 3 features an interesting 2D structure with its 1D double chain looking like a folded paper lantern. The optical band gaps were analyzed by diffuse-reflectance UV–Vis spectra. The photocatalytic experiments for these complexes reflect well on their activities for the decomposition of MB under the irradiation of high-pressure mercury lamp. Complexes 1 and 2 present extremely good photocatalytic properties with their photocatalytic activities increasing from 17% (without any catalyst) to 87% for 1 and 96% for 2 after 2h of irradiation. In addition, the luminescent properties of 1–3 have also been investigated.

Adsorption and photodegradation of methylene blue with Fe2O3-activated carbons under UV illumination in oxalate solution

Materials based on iron oxide (Fe2O3) and activated carbons (Fe-ACs) were prepared by pore volume impregnation of activated carbon in an iron nitrate solution followed by heat treatment at 250 °C. The Fe-AC materials were amorphous and microporous, and the specific surface areas (SBET) values were higher than 1000 m2/g. The effects of Fe content, porous properties, pH of the treatment solution, oxalic acid (OA) and MB concentrations were systematically investigated. The increase of the Fe content caused a significant decrease in the SBET values, lowering of the MB adsorption capacity and the photodegradation rate constant of the Fe-AC samples. The simultaneous processes of MB adsorption–photodegradation samples were complex owing to a strong influence of MB desorption during the photodegradation experiments under UV illumination. The MB decomposition was intensified by the enhanced simultaneous heterogeneous and homogeneous catalytic reactions. The almost complete simultaneous mineralization of MB and OA was confirmed by total organic carbon (TOC) analysis. The present system has advantages on the viewpoint of no hydrogen peroxide in operation, the low Fe leaching near neutral pH, no sludge formation, the possibility to recycle the iron promoter and cyclic usage.

Deposition of SnO2 on the Anatase TiO2 {105} Facets with High Photocatalytic Performance

AbstractAnatase TiO2 as a promising photocatalyst has been widely employed in the decontamination treatment of polluted water, air purification and water splitting. Coupling TiO2 with other semiconductor materials could further enhance the photocatalytic activity. Here, we successfully synthesized the SnO2/TiO2 catalyst by depositing SnO2 particles on the anatase TiO2 {105} facets through a gas phase oxidation process. The SnO2/TiO2 catalyst shows higher photocatalytic activity for decomposition of MB than that of the pure TiO2 catalyst. The enhanced photocatalytic activity can be attributed to the efficient charge separation since TiO2 and SnO2 catalyst have staggered energy level.

Highly efficient treatment of industrial wastewater by solution plasma with low environmental load

Advanced oxidation techniques are efficient processes to dispose of organic contaminants in industrial wastewater with low secondary pollution. The solution plasma technique was featured as an advanced oxidation technique with low secondary pollution and high efficiency. However, the solution plasma technique reported previously could only treat wastewater of less than 200 mL owing to the limited plasma generated by only one pair of electrodes. In this work, multiple pairs of electrodes were installed at the bottom of the reaction vessel to generate plasma for decomposing methylene blue trihydrate (MB) and methyl orange (MO) solutions with a batch amount of 18 L/batch. The solution plasma technique was compared with direct ozonation in decomposition of MB and MO wastewater. A surprising phenomenon is that MO was more readily decomposed than MB by using direct ozonation, whereas the removal of MO was too low, and MB was more readily decomposed than MO by using the solution plasma technique.

Catalytic oxidation for elimination of methyl bromide fumigation emissions using ceria-based catalysts

Methyl bromide (CH3Br, MB) is an effective chemosterilant in quarantine and pre-shipment (QPS) chamber fumigation applications. Efficient methods to destroy or capture and reuse spent MB in QPS operations are required in view of the recognized ozone depleting potential of MB. Oxidation of 34,000ppmv MB in simulated QPS airstreams was examined over catalysts composed of Pt, Pd, Fe2O3, CuO, or PbO nanoparticles on oxide (Al2O3, SiO2, and TiO2) or mixed-oxide (CeO2–Al2O3, CeO2–SiO2, and CeO2–TiO2) supports, and by self-assembled core–shell catalysts (Pd@SiO2 and Pd@10%CeO2–Al2O3). The most effective support by far was ceria. The effect of noble metal doping was modest; Pt was more active than Pd in CeO2–Al2O3 based catalysts, while Pd was more active than Pt in TiO2 based catalysts. The most effective catalyst tested was 1%Pt/30%CeO2–Al2O3, with 100%CeO2 being only slightly less effective. Using 1%Pt/30%CeO2–Al2O3, MB was completely oxidized at 400°C, independent of airstream humidification, to give HBr as the initial product, which was subsequently oxidized to Br2 by a Deacon-type reaction. The selectivity for Br2 in MB decomposition increased with temperature, maximizing at ∼90% at ∼350°C, and was slightly less favored in a humidified air stream. Bromide builds up on the catalyst at temperatures below 300°C, but burns off as the temperature increases. Catalytic oxidation by ceria-based catalysts appears to be a promising approach for eliminating MB from QPS fumigation emissions.

One-pot microwave mediated growth of heterostructured ZnO@AlSi as a potential dual-function eco-catalyst for treating hazardous pollutants in water resources

Dual function, eco-catalyst material had been designed with nano ZnO@aluminosilicate mineral (ZnO@AlSi) and processed via microwave assisted in situ intercalation and crystal growth reactions. Dual function of ZnO@AlSi was confirmed by the simultaneous adsorption and UV photoreduction of carcinogenic Cr(VI) to non-toxic Cr(III) and photooxidation of phenol and methylene blue dye (MB); a co-existed model system was simulated and prepared together in laboratory conditions. Single phase nano ZnO and ion exchanged AlSi layered silicates were also separately prepared for comparisons with ZnO@AlSi system. All these materials were characterized for BET, DLS, TGA, SEM, TEM, UV–visible and fluorescence spectrophotometry to analyze structural, thermal, morphological, and optical properties. It was seen that the inherent silicate layered structure significantly restricted the growth of ZnO, resulting in mesoporous, UV-active ZnO@AlSi heterogeneous nanocatalyst. An effective adsorption of Cr(VI), phenol and MB to the extent of 99% and the transformation of Cr(VI) to Cr (III) through photoreduction, and decomposition of phenol and MB by photooxidation followed by mineralization were achieved at once. This synergic adsorption and photodecomposition effects could not be found together in single phase nano ZnO as well as ion exchanged AlSi system. The kinetic photo-experiments indicated that reduction of Cr(VI) and degradation of phenol and MB by ZnO@AlSi followed Langmuir–Hinshelwood first-order kinetic model. The investigation of ZnO@AlSi at Cr(VI)/phenol and Cr(VI)/MB binary systems displayed high decontamination performance of ZnO@AlSi than in single pollutant system due to the arresting of electron–hole pair recombination via consuming both the members in separate redox half-reactions. Alternatively, life time of catalyst was found decreased in organic–inorganic pollutant system compared to single component systems. In summary, a dual function catalyst was designed through a facile technique and validated for the cost-effective removal and decomposition of organic and inorganic pollutants simultaneously in the complex wastewater.

Preparation and Properties of Zno/Vermiculite Composite Particles

ZnO/vermiculite as the novel photocatalysts were prepared by two approachs: one is mixtures of ZnO and different acid treated vermiculite, and another is sol-gel method. The acid activated vermiculite as a new promising catalyst support and adsorbent has a large capacity of absorption, high surface area and thermal stability. The activity of catalyst has been interrelated to support and ZnO. Based on the important effect of support on ZnO/vermiculite photocatalysts, treatment of vermiculite by nitric acid of different concentration was studied by evaluated in the photocatalytic decomposition of MB with resulting photocatalysts. BET surface area measurement and X-ray diffraction (XRD) analysis were used to characteristic of ZnO particle in acid treated vermiculite structure and the phase structure and crystallization index of ZnO in the modified vermiculite mineral. Results showed the ZnO-vermiculite combination possessing higher photocatalytic activity due to the synergistic effect when compared to the commercial ZnO.

Preparation and Properties of Zno/Vermiculite Composite Particles

ZnO/vermiculite as the novel photocatalysts were prepared by two approachs: one is mixtures of ZnO and different acid treated vermiculite, and another is sol-gel method. The acid activated vermiculite as a new promising catalyst support and adsorbent has a large capacity of absorption, high surface area and thermal stability. The activity of catalyst has been interrelated to support and ZnO. Based on the important effect of support on ZnO/vermiculite photocatalysts, treatment of vermiculite by nitric acid of different concentration was studied by evaluated in the photocatalytic decomposition of MB with resulting photocatalysts. BET surface area measurement and X-ray diffraction (XRD) analysis were used to characteristic of ZnO particle in acid treated vermiculite structure and the phase structure and crystallization index of ZnO in the modified vermiculite mineral. Results showed the ZnO-vermiculite combination possessing higher photocatalytic activity due to the synergistic effect when compared to the commercial ZnO.

Highly efficient and stable Ag/Ag3PO4 plasmonic photocatalyst in visible light

A highly efficient and stable photocatalyst Ag/Ag 3 PO 4 was prepared by the ion-exchange process between AgNO 3 and Na 2 HPO 4 and subsequently light-induced reduction route. The diffuse reflectance spectra (DRS) indicated Ag/Ag 3 PO 4 had strong absorption in UV and visible-light regions. The composite showed excellent visible-light-driven photocatalytic performance. It can decompose organic dye within several minutes and still maintain a high level activity even though used five times. It is considered that this excellent performance results from the surface plasmon resonance of Ag nanoparticles and a large negative charge of PO 4 3 − ions. ► Ag/Ag 3 PO 4 photocatalyst was synthesized by light-induced formation method. ► Content of Ag 0 reaches to 5.25% (mol %) after 2 hour irradiation. ► MB decomposition rate over Ag/Ag 3 PO 4 dozens of times quicker than over N-TiO 2 . ► It maintains a high level activity after recycling five times.