Degradation by irradiation of an Acid Orange 7 on colloidal TiO2/(LDHs) (original) (raw)
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Environmental Technology & Innovation, 2018
The photocatalytic degradation of a model azo dye acid orange 7 (AO7) by Fe 3+-doped TiO 2 nanocatalyst has been studied under UV, Visible (λ > 400 nm) and solar light irradiation. The role of hydrogen peroxide to enhance the catalyst's efficiency was examined. The reaction pathway of complete mineralization was investigated by monitoring the temporal evolution of reaction intermediates and low molecular weight organic acids (LMWOA) as final products in solution. These LMWOAs are oxidized eventually to inorganic ions such a nitrate, sulfate, oxalate etc, which are confirmed using GC-MS, UV-Vis and Ion Chromatographic analyses. The optimized condition of photocatalytic degradation were obtained for degradation under different light source. The Fe 3+-doped TiO 2 showed high dye degradation efficiency under both UV (100%), visible (100%) and solar light (90%) which distinguishes Fe 3+-doped TiO 2 from materials in literature that are only efficient in particular light source for dye degradation. Furthermore, the Fe 3+ doped titania photocatlysts are stable and can maintain performance upto 6 recycle use. Reaction kinetics for UV and solar light induced degradation followed first order reaction whereas visible light degradation followed a zero-order reaction.
Journal of Photochemistry and Photobiology A: Chemistry, 2003
Anionic (Alizarin S (AS), azo-Methyl Red (MR), Congo Red (CR), Orange G (OG)) and cationic (Methylene Blue (MB)) dyes were degraded, either individually or in mixtures, by using UV-irradiated TiO 2 in suspension or supported on glass and on paper. The influence of the chemical structure of different dyes as well as that of pH and of the presence of inorganic salts on the photocatalytic properties of TiO 2 has been discussed. The role of adsorption is suggested, indicating that the reaction occurs at the TiO 2 surface and not in the solution. S and N hetero-atoms are respectively mineralized into SO 4 2− , NO 3 − and NH 4 + , except azo-groups which mainly formed N 2 which represents an ideal case for a decontamination reaction. The fate of nitrogen strongly depends on its initial oxidation degree. High photocatalytic activities have been found for TiO 2 coated on glass by the sol-gel method. Its efficiency was intermediate between those of PC-500 and P-25 powders. The efficiency of PC-500 TiO 2 sample, fixed on paper by using a binder, is slightly less important than that of the powder. The presence of a silica-binder with an acidic pzc is suggested to be at the origin of the decrease in efficiency.
Nanostructured mesoporous TiO2 particles with high specific surface area and average crystallite domain sizes in the range of 2 nm-30 nm have been synthesized via sol-gel and hydrothermal techniques. The as-produced nanoparticles have been characterized via X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area analysis, Fourier Transform Infra-Red, and Raman Spectroscopy as a function of temperature for their microstructure, morphology, optical, porosity and absorption properties. The as-synthesized TiO2 nanostructures were attempted as catalysts in the photocatalytic degradation of Rhodamine B and Sudan III dyes in a batch reactor under UV light. The results show that for catalysts calcined at 300 °C, ~100 % degradation of Sudan III dye was observed when Hydrothermal based catalyst was used whiles ~ 94 % degradation of Rhodamine B dye was observed using the sol-gel based catalysts. These synthesized TiO2 nanoparticles have promising potential applications in the degradation of a wide range of dye pollutants.
Photocatalytic Activity of Defective TiO2-x for Water Treatment/Methyl Orange Dye Degradation
Chemistry & Chemical Technology
This study is designed to highlight photocatalytic activity of TiO2 nanoparticles in methyl orange (MO) dye degradation. Titanium dioxide TiO2 nanopowder was synthesized by conventional sol-gel method and calcined in air atmosphere at different temperatures 350C, 550C and 850C. The prepared TiO2 nanoparticles then were subjected to a solid state reaction with calcium hydride (CaH2) at the same temperatures but calcined in argon atmosphere. X-Ray Diffraction (XRD) measurements used for phase and crystalline size identification showed that the obtained samples have the same TiO2 anatase phase, but the crystalline size decreased after reduction treatment. The electronic properties obtained via UV spectroscopy showed the decrease in calculated energy gap from 3.3 eV for prepared TiO2-550 to 2.65 eV for reduced TiO2-CaH2-550, which extend the absorption spectra toward visible light region. Energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM) measurements reveale...
Egyptian Journal of Petroleum, 2014
M-doped TiO 2 nanoparticles (M = Cu, Zn) were prepared by the sol-gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and UV-vis spectroscopy techniques were used to characterize the samples. Photocatalytic activities of samples for methyl orange (MO) degradation and the chemical oxygen demand (COD) were investigated. XRD results confirmed the formation of the anatase phase for the TiO 2 nanoparticles, with crystallite sizes in the range of 9-21 nm. The small crystallite size and doping ions (Cu and Zn) inhibited any phase transformation and promoted the growth of the TiO 2 anatase phase. The optical study showed that doping ions lead to an increase in the absorption edge wavelength, and a decrease in the band gap energy of TiO 2 nanoparticles. The doped TiO 2 nanoparticles in general showed higher photocatalytic activities than the pure ones. The Cu doped TiO 2 nanoparticles showed the best photocatalytic activity based on the measured COD values.
Visible light-induced photocatalytic degradation of Acid Orange 7 in aqueous TiO2 suspensions
Applied Catalysis B: Environmental, 2004
The photocatalytic activity of magnetic bentonite, Fe 3 O 4 nanoparticles decorated Al-pillared bentonite (Fe 3 O 4 /Al-B), for the degradation of rhodamine B (RhB) in the presence of H 2 O 2 under visible light (VL) was evaluated. The effects of different reaction parameters such as catalyst dose, dye concentration and externally added H 2 O 2 were also investigated. The magnetic bentonite showed good photocatalytic activity, magnetic separability and stability for repeated use. More than 95% of 40 mg/L RhB was converted within 3 h under VL with a catalyst dose of 0.5 g/L. Suitable mechanisms have been proposed to account for the photocatalytic activities in the presence and absence of H 2 O 2. The efficiency of H 2 O 2 in VL process was much higher than that of the dark process. Results obtained in the current study may be useful to develop a suitable photocatalyst for photocatalytic remediation of different water contaminants including organic dyes.
This study deals with the synthesis of TiO 2 supported Moroccan palygorskite fibers and their use as photocatalyst for the removal of Orange G pollutant from wastewater. The TiO 2-palygorskite nanocomposite synthesis was accomplished according to a colloidal route involving a cationic surfactant as template (hexadecyltrimethylammonium bromide) assuring hence organophilic environment for the formation of TiO 2 nanoparticles. The clay minerals samples were characterized before and after functionalization with TiO 2. Anatase crystallizes above ca. 450°C and remarkably remains stable up to 900°C. In contrast, pure TiO 2 xerogel obtained from titanium tetraisopropoxide (TTIP) showed before calcination a nanocrystalline structure of anatase. By increasing the temperature, anatase readily transforms into rutile beyond 600°C. The remarkable stability at high temperature of anatase particles immobilized onto palygorskite microfibers was due to the hindrance of particles growth by sintering. Homogeneous monodisperse distribution of anatase particles with an average size of 8 nm was found by TEM and XRD onto palygorskite fibers. This anatase particle size remains below the nucleus critical size (ca. 11 nm) required for anatase-rutile transition. The TiO 2 supported palygorskite sample annealed in air at 600°C for 1 h exhibits the highest photocatalytic activity towards the degradation of Orange G compared to nanocomposite samples prepared under different conditions as well as pure TiO 2 powders obtained from the xerogel route or commercially available as Degussa P25.
Nanostructured mesoporous titanium dioxide (TiO 2) particles with high specific surface area and average crystallite domain sizes within 2 nm and 30 nm have been prepared via the sol-gel and hydrothermal procedures. The characteristics of produced nanoparticles have been tested using X-Ray Diffraction (XRD), BrunauereEmmetteTeller (BET) surface area analysis, Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR), and Raman Spectroscopy as a function of temperature for their microstructural, porosity, morphological, structural and absorption properties. The as-synthesized TiO 2 nanostructures were attempted as catalysts in Rhodamine B and Sudan III dyes' photocatalytic decomposition in a batch reactor with the assistance of Ultra Violet (UV) light. The results show that for catalysts calcined at 300 C, w100 %
TiO2 sol was synthesized under mild conditions (25 ± 1°C and ambient pressure) by hydrolysis of titanium isopropoxide in aqueous solution and subsequent reflux to enhance crystallization. The material was characterized by X-ray diffraction, transmission electron microscopy, and Fourier transform infrared. The synthesized sample presented a pure phase anatase with nanometric particle size. The photodegradation of reactive dyes (malachite green, methylene blue, and rhodamine B) and industrial effluents was elucidated in aqueous suspension containing titania nanoparticles under UV irradiation. Also, the effect of pH in nanoparticle synthesis and role of catalyst dose and dye concentration were evaluated. The experimental result showed that particles synthesized by sol–gel method are of 20–40 nm anatase form with cuboidal structure and OH− as a major functional group. These particles showed efficiency to degrade dyes up to 98% and industry (paint and textile) effluents can be decolorized in the TiO2/UV system. Keywords: Methylene Blue; Malachite Green; Rhodamine B; Industrial effluents; TiO2 adsorbent; Photocatalysis