C4+ and S4+-codoped titanium dioxide (TiO2) having a rutile phase was prepared. By doping C4+ and S4+ ions into a TiO2 lattice, the absorption edge of rutile TiO2 powder was largely shifted from 400 to 700 nm. 2-Methylpyridine and methyleneblue were photocatalytically oxidized at high efficiency on C4+ and S4+-doped TiO2 under visible light at a wavelength longer than 5 nm. 相似文献
In this work, a series of titania-supported NiO and CdO materials were synthesized by a modified sol-gel process. The prepared photocatalysts were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), and transmission electron microscopy (TEM). The activities of titania-supported NiO and CdO photocatalysts for photocatalytic degradation of Remazole Red F3B (RR) dye, under simulated sunlight, were investigated. The photocatalytic mineralization of an RR dye solution over various NiO-x/TiO2 and CdO-x/TiO2 photocatalysts under simulated sunlight was investigated. It was worthy noticing that the photocatalytic activity of titania improved using the prepared catalysts. The prepared TiO2, NiO-5/TiO2, and CdO-2/TiO2 photocatalysts exhibited higher photocatalytic activity under simulated sunlight than did commercial TiO2. The prepared photocatalysts were stable after photocatalytic degradation of the dye. The observed photocatalytic mineralization of the dye was 51 and 71% over NiO-10/TiO2 and CdO-2/TiO2 after 180 min of irradiation, respectively. Juxtaposing a p-NiO-5/TiO2 semiconductor provided a potential approach for decreasing charge recombination. The prepared photocatalystsNiO-5/TiO2 and CdO-2/TiO2 are promising composites for the solar detoxification of textile wastewater. 相似文献
Several TiO2-based photocatalytic systems that have considerable visible light response have been developed, such as the photodegradation
of organic pollutants on sensitized TiO2 by visible light, construction of visible-light-active novel TiO2 photocatalysts by matrix or surface modification. In this paper, we review briefly our recent progress in the TiO2 photocatalytic degradation of organic pollutants by visible light, some related work by other groups is also involved. 相似文献
In this paper, ZnBiSbO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiSbO4 had been characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, transmission electron microscope and UV-visible spectrometer. ZnBiSbO4 crystallized with a pyrochlore-type structure and a tetragonal crystal system. The band gap of ZnBiSbO4 was estimated to be 2.49 eV. The photocatalytic degradation of indigo carmine was realized under visible light irradiation with ZnBiSbO4 as a catalyst compared with nitrogen-doped TiO2 (N-TiO2) and CdBiYO4. The results showed that ZnBiSbO4 owned higher photocatalytic activity compared with N-TiO2 or CdBiYO4 for the photocatalytic degradation of indigo carmine under visible light irradiation. The reduction of the total organic carbon, the formation of inorganic products, SO42− and NO3−, and the evolution of CO2 revealed the continuous mineralization of indigo carmine during the photocatalytic process. One possible photocatalytic degradation pathway of indigo carmine was obtained. The phytotoxicity of the photocatalytic-treated indigo carmine (IC) wastewater was detected by examining its effect on seed germination and growth. 相似文献
The photocatalytic degradation of polyethylene (PE) plastic was carried out directly under the sunlight irradiation with polypyrrole/TiO2 (PPy/TiO2) nanocomposite as photocatalyst, which prepared by sol-gel and emulsion polymerization methods. The photocatalytic degradation efficiency was determined by weight loss monitoring, gel permeation chromatography (GPC), atomic force microscopic (AFM) and FT-IR analysis. The photocatalytic degradations of PE plastic with pure TiO2 and PPy were also investigated and compared with that of PPy/TiO2. It was noticed that irradiating the PE plastic for 240 h by sunlight reduced its weight up to 35.4% and 54.4% of Mw, respectively. The AFM images showed the formation of cavities on PE plastic surface. FT–IR spectroscopic studies indicated that a strong interaction existed between the interface of PE and PPy/TiO2 and caused the degradation of PE. The photocatalytic degradation mechanism was also discussed briefly. 相似文献
The development of visible light-responsive TiO2 (Vis-TiO2) thin films has been achieved by applying a radio-frequency magnetron sputtering deposition (RF-MS) method. Pt-loaded Vis-TiO2 thin films act as photocatalysts to decompose water involving sacrificial reagent such as methanol or silver nitrate even
under visible light (λ ≧ 420 nm) irradiation. It was also found that Pt-loaded Vis-TiO2 thin films decompose pure water into H2 and O2 stoichiometrically under light irradiation of wavelengths longer than 390 nm. Vis-TiO2 thin films exhibit columnar structures perpendicular to the substrate and a declined composition of the O/Ti ratio from the
surface (O/Ti = 2.00) to bottom (O/Ti = 1.93). This unique structure (anisotropic structure) of Vis-TiO2 can be considered an important factor in the modification of the electronic properties of Vis-TiO2 thin films, enabling the absorption of visible light. Furthermore, the effect of the Pt loadings on the photocatalytic activity
of the TiO2 thin films was investigated and the optimum Pt loading was determined to be 21 μ g/cm2 as Pt metal 相似文献
A mesoporous TiO2 precursor has been prepared by the hydrothermal condensation of tetrabutyltitanate in presence of an alkylamine template by three different methods. The surfactants were removed from as-synthesized TiO2 by calcination and solvent extraction methods. A potential photocatalyst, predominantly present as an anatase phase, was produced in the latter case. The samples were characterized by XRD, FT-IR, low-temperature N2 adsorption-desorption measurement and solid state UV-visible diffuse reflectance spectroscopy. The photocatalytic activities of all TiO2 samples were compared using the degradation of phenol as a probe reaction. 相似文献
TiO2 nanoparticles on calcined sewage sludge (TiO2/sludge) were prepared by the sol-gel method and were fully characterized. The photocatalytic efficiency of TiO2/sludge was evaluated by tartrazine dye degradation by halide lamp. TiO2/sludge exhibited a high photocatalytic oxidation efficiency (more than 90%) of tartrazine compared with naked TiO2 (less than 20%) due to the synergy effect of sewage sludge. The optimization of experimental conditions was 0.5 g/l TiO2/Sludge, pH 8 with 50 mg/l tartrazine dye. The addition of sewage sludge to TiO2 improves the efficiency of dye mineralization. The prepared catalyst showed easier separation and effective reuse. 相似文献
A series of catalysts, NiSO4/TiO2–ZrO2 having different TiO2–ZrO2 composition, for acid catalysis was prepared by the impregnation method using an aqueous solution of nickel sulfate. The
addition of TiO2 to ZrO2 improved the surface area of the catalyst and enhanced its acidity remarkably because of the formation of new acid sites
through the charge imbalance of Ti–O–Zr bonding. The binary oxide, TiO2–ZrO2 calcined above 600 °C resulted in the formation of crystalline orthorhombic phase of ZrTiO4. Therefore, NiSO4/TiO2–ZrO2 calcined at 500 °C exhibited a maximum catalytic activity for acid catalysis, and then the catalytic activity decreased with
the calcination temperature. The correlation between catalytic activity and acidity held for both reaction, 2-propanol dehydration
and cumene dealkylation. NiSO4 supported on 50TiO2–50ZrO2 (TiO2/ZrO2 ratio = 1) among TiO2–ZrO2 binary oxides exhibited the highest catalytic activity for acid catalysis. 相似文献
Sr2TiO4 is a promising photocatalyst for antibiotic degradation in wastewater. The photocatalytic performance of pristine Sr2TiO4 is limited to its wide bandgap, especially under visible light. Doping is an effective strategy to enhance photocatalytic performance. In this work, Nb/N co-doped layered perovskite Sr2TiO4 (Sr2TiO4:N,Nb) with varying percentages (0–5 at%) of Nb were synthesized by sol-gel and calcination. Nb/N co-doping slightly expanded the unit cell of Sr2TiO4. Their photocatalytic performance towards antibiotic (tetracycline) was studied under visible light (λ > 420 nm). When Nb/(Nb + Ti) was 2 at%, Sr2TiO4:N,Nb(2%) shows optimal photocatalytic performance with the 99% degradation after 60 min visible light irradiation, which is higher than pristine Sr2TiO4 (40%). The enhancement in photocatalytic performance is attributed to improving light absorption, and photo-generated charges separation derived from Nb/N co-doping. Sr2TiO4:N,Nb(2%) shows good stability after five cycles photocatalytic degradation reaction. The capture experiments confirm that superoxide radical is the leading active species during the photocatalytic degradation process. Therefore, the Nb/N co-doping in this work could be used as an efficient strategy for perovskite-type semiconductor to realize visible light driving for wastewater treatment. 相似文献
The influence of the direction of ultraviolet irradiation upon the yields of the photocatalytic decomposition of pure water has been investigated in Pt/TiO2 aqueous suspension system. The yields of the photocatalytic decomposition irradiated from the top of the reaction cell are about 103 times higher than those irradiated from the bottom. The difference seems due to the reverse reaction of the formed H2 and O2 in the suspension. 相似文献
Low temperature rf-plasma was used to test the changes in the chemical and physical properties of a plasma-treated polymeric
membrane made from C7H5F3 and SiH4, two materials that are very thermally, chemically, and mechanically stable. C7H5F3 and SiH4, plasma polymers were efficiently deposited to an aluminum oxide substrate with a pore size of 0.02μ. Even though the amount of the monomer C7H5F3 increased, there was no significant change in the permeability of oxygen. However, selectivity of oxygen over nitrogen increased
noticeably. Also, when the plate distance of the supporter from the cathode head within the reactor was 4 cm, the concentration
gradients of C7H5F3 and SiH4 were the greatest. This resulted in the maximum value of permeability and selectivity and allowed the creation of a plasma-treated
polymeric membrane with such characteristics when the composite permeation coefficient ranged from 4,500-7,500 GJ.s/kg. 相似文献
TiO2:Au-based photocatalysis represents a promising alternative to remove contaminants of emerging concern (CECs) from wastewater under sunlight irradiation. However, spherical Au nanoparticles, generally used to sensitize TiO2, still limit the photocatalytic spectral band to the 520 nm region, neglecting a high part of sun radiation. Here, a ligand-free synthesis of TiO2:Au nanostars is reported, substantially expanding the light absorption spectral region. TiO2:Au nanostars with different Au component sizes and branching were generated and tested in the degradation of the antibiotic ciprofloxacin. Interestingly, nanoparticles with the smallest branching showed the highest photocatalytic degradation, 83% and 89% under UV and visible radiation, together with a threshold in photocatalytic activity in the red region. The applicability of these multicomponent nanoparticles was further explored with their incorporation into a porous matrix based on PVDF-HFP to open the way for a reusable energy cost-effective system in the photodegradation of polluted waters containing CECs. 相似文献
A series of catalysts, NiSO4/Al2O3–TiO2, for acid catalysis was prepared by the impregnation method, where support, Al2O3–TiO2 was prepared by the coprecipitation method using a mixed aqueous solution of titanium tetrachloride and aluminum nitrate
solution followed by adding an aqueous ammonia solution. The addition of nickel sulfate (or Al2O3) to TiO2 shifted the phase transition of TiO2 from amorphous to anatase to higher temperature because of the interaction between nickel sulfate (or Al2O3) and TiO2. 15-NiSO4/5-Al2O3–TiO2 containing 15 wt% NiSO4 and 5 mol% Al2O3, and calcined at 400°C exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation.
The catalytic activities for both reactions were correlated with the acidity of catalysts measured by the ammonia chemisorption
method. The charge transfer from Ti atoms to the neighboring Al atoms strengthens the Al–O bond between Al and the surface
sulfate species. The addition of Al2O3 up to 5 mol% enhanced the acidity, thermal property, and catalytic activities of NiSO4/Al2O3–TiO2 gradually due to the interaction between Al2O3 and TiO2 and consequent formation of Al–O–Ti bond. 相似文献
A series of Zr(SO4)2/TiO2 catalysts were prepared by impregnation of powder TiO2 with an aqueous solution of zirconium sulfate. No diffraction line of zirconium sulfate was observed up to 30 wt%, indicating
good dispersion of Zr(SO4)2 on the surface of TiO2. The high catalytic activities of Zr(SO4)2/TiO2 for both 2-propanol dehydration and cumene dealkylation were related to the increase of acidity and acid strength due to
the addition of Zr(SO4)2. Zr(SO4)2/TiO2 containing 25% zirconium sulfate and calcined at 400 °C exhibited maximum catalytic activities for 2-propanol dehydration
and cumene dealkylation. The catalytic activities for these reactions were correlated with the acidity of catalysts measured
by the ammonia chemisorption method.
This paper is dedicated to Professor Hyun Ku Rhee on the occasion of his retirement from Seoul National University. 相似文献
In this contribution, an Ag/g‐C3N4 nanocomposite was synthesized and utilized as highly efficient and green photocatalyst for organic reactions under visible light irradiation. A layered, porous g‐C3N4 was synthesized following a modified solvothermal‐roasting process by using melamine and cyanuric chloride as precursor. Silver nanoparticles (NPs) were well anchored on g‐C3N4 nanosheets, which were prepared by a facile impregnation–roasting method. The inexpensive, stable g‐C3N4 coupled with the localized surface plasmon resonance (LSPR) effect of Ag NPs exhibited high photocatalytic activities toward aerobic oxidative amidation of aromatic aldehydes under visible light irradiation. Good to excellent yields were achieved for various substrates under the light of a 25 W compact fluorescent light (CFL) bulb in air. The operationally easy procedure provides an economical, green, and mild alternative for the formation of amide bonds.
In this study, TiO2, ZnO, TiO2/ZnO (Ti/Zn), and TiO2/ZnO/Sep (Ti/Zn/Sep) catalysts have been synthesized using sol–gel and chemical precipitation method. Their photocatalytic performances have been compared using Flumequine (FLQ) antibiotic. X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), N2-adsorption, and the determination of a zero point charge has been used to characterize the synthesized catalysts. The degradation studies showed that the catalytic efficiency of Ti/Zn/Sep is higher than that for other catalysts. The operational parameters such as pH, initial FLQ concentration, and catalyst dosage were evaluated. UV–vis and high-resolution mass spectroscopy (HRMS) analyses were used to determine the degradation efficiency and products. ZnO played a major role in the FLQ degradation process, and sepiolite contributed to adsorption of FLQ on the catalyst surface enormously. The catalysts exhibited 11%, 23%, 63%, and 85% degradation efficiency for ZnO, TiO2, Ti/Zn, and Ti/Zn/Sep in the decomposition of FLQ, respectively. 相似文献
Palladium doped titania nanoparticles supported on carbon-covered alumina (CCA/Pd-TiO2) impregnated polysulfone (PS) membranes were prepared by the phase inversion technique. The nano-sized CCA/Pd-TiO2 nanoparticles were uniformly dispersed in 18 wt% PS casting solution to synthesize CCA/Pd-TiO2 polysulfone membranes (PS/CCA/Pd-TiO2). The amount of the CCA/Pd-TiO2 was varied between 0.25% and 0.5% to form two types of membranes. These were casted on a non-woven fabric. The nanoparticles were added in order to enhance the photodegradation potential of the PS membranes under visible light. Raman, XRD, SEM, TGA, TGA-FTIR was used to characterize the membranes. The mechanical strength of the membranes was determined with an Instron tensile tester. The SEM results suggested that these membranes had a high degree of porosity and the nanoparticles were distributed on and within the PS membrane. The Raman analysis revealed the presence of the nanoparticles within the membrane matrix while the XRD results exposed the probability of interactions between the polymer and the nanoparticles. The two membranes were then tested for their capability to photodegrade Rhodamine B under visible light illumination. The 0.5% PS/CCA/Pd-TiO2 membrane photodegraded 80.4% of the dye while the 0.25% PS/CCA/Pd-TiO2 membrane degraded 70.8% of Rhodamine B over a 270 min period. The photodegradation followed a pseudo first-order reaction rate and the apparent rates were 0.00597 and 0.00448 min?1 for 0.5% PS/CCA/Pd-TiO2 membrane and 0.25% PS/CCA/Pd-TiO2, respectively. 相似文献