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1.
Maria Kositzi Ioannis Poulios Konstantini Samara Euthimia Tsatsaroni Efthymios Darakas 《Journal of hazardous materials》2007
The photocatalytic degradation of Cibacron Yellow LS-R (CIY), an azo dye, has been investigated in aqueous heterogeneous solutions containing semiconductor oxides as photocatalysts. The disappearance of the organic molecule follows approximately a pseudo-first kinetic order according to the Langmuir–Hinshelwood model. Various commercial photocatalysts are compared with respect to their decolorization efficiency, the COD, as well as the toxicity reduction. The effect of the temperature on the reaction rate is ascertained. 相似文献
2.
Jirapat Ananpattarachai Puangrat Kajitvichyanukul Supapan Seraphin 《Journal of hazardous materials》2009
Nitrogen-doped TiO2 was developed to enable photocatalytic reactions using the visible range of the solar spectrum. This work reports on the synthesis, characterisation and kinetic study of interstitial N-doped TiO2 prepared by the sol–gel method using three different types of nitrogen dopants: diethanolamine, triethylamine and urea. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and UV–visible spectroscopy were used to analyse the titania. Different interstitial N-doped TiO2 properties, such as absorption ability in the UV–visible light region, redshift in adsorption edge, good crystallisation and composition ratio of titania structures (anatase and rutile) could be obtained from different nitrogen dopants. Amongst investigated nitrogen precursors, diethanolamine provided the highest visible light absorption ability of interstitial N-doped TiO2 with the smallest energy bandgap and the smallest anatase crystal size, resulting in the highest efficiency in 2-chlorophenol degradation. The photocatalytic activity of all N-doped TiO2 can be arranged in the following order: TiO2/diethanolamine > TiO2/triethylamine > TiO2/urea > un-doped TiO2. The initial rate of 2-chlorophenol degradation using the interstitial N-doped TiO2 with diethanolamine was 0.59 mg/L-min and the kinetic constant was 2.34 × 10−2 min−1 with a half-life of 98 min. In all cases, hydroquinone was detected as a major intermediate in the degradation of 2-chlorophenol. 相似文献
3.
以钛酸丁酯、硝酸银为原料,采用溶胶-凝胶法制备不同浓度Ag掺杂TiO2光催化剂。分别采用X射线衍射(XRD)、扫描电子显微镜(SEM)、光电子能谱(XPS)、紫外可见漫反射(DRS)及荧光光谱(PL)等测试方法对样品晶体结构、表面形貌、化学成分和光学性质进行表征。以罗丹明B溶液(RhB)为目标降解物,分别采用汞灯与氙灯为光源,研究xAg-TiO2(x=1%,2%,4%,6%,原子分数)光催化剂在紫外光和模拟太阳光照射下的光催化活性。结果表明:Ag的加入降低了光生电子空穴的复合率,增加了对模拟太阳光的吸收,紫外光以及模拟太阳光的光催化活性均得到提升。1%Ag-TiO2表现出最好的光催化活性,在紫外光及模拟太阳光下对RhB的降解率分别为91%与89%,是纯TiO2的1.18倍和1.24倍,反应速率常数k分别为0.01257 min^-1和0.01150 min^-1,是纯TiO2的1.49倍和1.74倍。 相似文献
4.
Diclofenac photodegradation under simulated sunlight: Effect of different forms of nitrogen and kinetics 总被引:7,自引:0,他引:7
A synthetic non-steroidal anti-inflammatory drug diclofenac is one of the most frequently detected pharmaceuticals in various water samples. One of the most important degradation processes relating to diclofenac is its photodegradation in the aquatic environment. This paper studies the kinetic model for diclofenac degradation in water and the variation of the photodegradation of diclofenac in the presence of different forms of nitrogen changes with different pE values in the aquatic environment under simulated sunlight. The results demonstrate that degradation pathways proceed via pseudo first-order kinetics in all cases and the photodegradation of diclofenac is the sum of the degradation by direct photolysis and self-sensitization. NO3− and NO2− have inhibiting effects on the photodegradation of diclofenac. The different forms of nitrogen changes with different pE values and this has a significant influence on the photodegradation of diclofenac. The results show that when NH4+ and NO2− coexist in the aquatic environment, the inhibiting effect on the photodegradation diclofenac is less than the sum of the partial inhibiting effects. The results indicated that NO2− had an obvious antagonistic action for NH4+. When NO3− and NO2− coexisted in the aquatic environment, a similar antagonistic action between NO3− and NO2− was observed. 相似文献
5.
Chemical modification of titanium to form TiO2 is being extensively pursued. We compare the influence of acid pickling and post processing on the crystallinity and morphology of TiO2 grown by H2O2 oxidation. Subsequent oxidation using two concentrations of H2O2 (15% and 30% by mass) indicates a variation in the fine surface morphology, apparent at low magnifications. No discernable difference in the quality of TiO2 that was produced when evaluated by SEM, Raman or XRD (glancing angle and θ:2θ) could be detected between the samples oxidised in different H2O2 concentrations. The photoactivity of TiO2 produced from ultra thin Ti films was confirmed by the photocatalytic reduction of Ag+ cations to Ag0. 相似文献
6.
Photocatalytic decolorization of methylene blue in the presence of TiO2/ZnS nanocomposites 总被引:1,自引:0,他引:1
Franco A Neves MC Carrott MM Mendonça MH Pereira MI Monteiro OC 《Journal of hazardous materials》2009,161(1):545-550
The synthesis of distinct nanocrystalline TiO2 capped ZnS samples was carried out using a chemical deposition method. The materials characterization showed that the presence of ZnS onto TiO2 surface results in a red shift of the material band edge when compared with the initial semiconductor. The photocatalytic activity of the prepared nanocomposites was tested on the decolorization of methylene blue (MB) aqueous solutions. The dye photodecolorization process was studied considering the influence of experimental parameters such as catalyst concentration, TiO2/ZnS ratio, pH and methylene blue adsorption rate. The material with the best catalytic activity towards the methylene blue photodecolorization was the TiO2 doped with 0.2% of ZnS. The complete photodecolorization of a 20ppm methylene blue solution, at natural pH was achieved in less than 20min, nearly 70min faster than the TiO2 photoassisted process. 相似文献
7.
I. Turkevych Y. Pihosh M. Goto A. Kasahara M. Tosa S. Kato K. Takehana T. Takamasu G. Kido N. Koguchi 《Thin solid films》2008,516(9):2387-2391
The effective one-step physical approach is demonstrated for the fabrication of anatase titanium dioxide nanotubes through r.f. magnetron sputtering of TiO2 on a highly ordered nanoporous anodic alumina template. The nanostructured TiO2 benefited from the combination of unique properties of both the sputtering technique that provided well-controlled environment for the fabrication of anatase phase TiO2 and the porous anodic alumina (PAA) that provided uniform and ordered nanopores. The photocatalytic properties of TiO2 films were characterized following the degradation of methylene blue molecules under UV light irradiation. The photocatalytic activity of the nanostructured TiO2 films has been found to be approximately twice higher in comparison with the flat TiO2 films fabricated at the same conditions. 相似文献
8.
Vassileios C. Papadimitriou Vassileios G. StefanopoulosManolis N. Romanias Panos Papagiannakopoulos Kyriaki SambaniValentin Tudose George Kiriakidis 《Thin solid films》2011,520(4):1195-1201
Titanium dioxide (TiO2) photocatalytic powder materials doped with various levels of manganese (Mn) were synthesized to be used as additives to wall painting in combating indoor and outdoor air pollution. The heterogeneous photocatalytic degradation of gaseous acetaldehyde (CH3CHO) on Mn-TiO2 surfaces under ultraviolet and visible (UV/Vis) irradiation was investigated, by employing the Photochemical Static Reactor coupled with Fourier-Transformed Infrared spectroscopy (PSR/FTIR) technique. Experiments were performed by exposing acetaldehyde (~ 400 Pa) and synthetic air mixtures (~ 1.01 × 105 Pa total pressure) on un-doped TiO2 and doped with various levels of Mn (0.1-33% mole percentage) under UV and visible irradiation at room temperature. Photoactivation was initiated using either UV or visible light sources with known emission spectra. Initially, the photo-activity of CH3CHO under the above light sources, and the physical adsorption of CH3CHO on Mn-TiO2 samples in the absence of light were determined prior to the photocatalytic experiments. The photocatalytic loss of CH3CHO on un-doped TiO2 and Mn-TiO2 samples in the absence and presence of UV or visible irradiation was measured over a long time period (≈ 60 min), to evaluate their relative photocatalytic activity. The gaseous photocatalytic end products were also determined using absorption FTIR spectroscopy. Carbon dioxide (CO2) was identified as the main photocatalysis product. It was found that 0.1% Mn-TiO2 samples resulted in the highest photocatalytic loss of CH3CHO under visible irradiation. This efficiency was drastically diminished at higher levels of Mn doping (1-33%). The CO2 yields were the highest for 0.1% Mn-TiO2 samples under UV irradiation, in agreement with the observed highest CH3CHO decomposition rates. It was demonstrated that low-level (0.1%) doping of TiO2 with Mn results in a significant increase of their photocatalytic activity in the visible range, compared to un-doped TiO2. This elevated activity is lost at high doping levels (1-33%). Finally, the photocatalytic degradation mechanism of CH3CHO on 0.1% Mn-TiO2 surfaces under visible irradiation leading to low CO2 yields is different than that under UV irradiation resulting to high CO2 yields. 相似文献
9.
Mahalakshmi M Vishnu Priya S Arabindoo B Palanichamy M Murugesan V 《Journal of hazardous materials》2009,161(1):336-343
Photocatalytic activity of TiO2 and zeolites supported TiO2 were investigated using propoxur as a model pollutant. Hbeta, HY and H-ZSM-5 zeolites were examined as supports for TiO2. Hbeta was chosen as the TiO2 support based on the adsorption capacity of propoxur on these zeolites (Hbeta>HY=H-ZSM-5). TiO2/Hbeta photocatalysts with different wt.% were prepared and characterized by XRD, FT-IR and BET surface area. The progress of photocatalytic degradation of aqueous propoxur solution using TiO2 (Degussa P-25) and TiO2 supported on Hbeta zeolite was monitored using TOC analyzer, HPLC and UV-vis spectrophotometer. The degradation of propoxur was systematically studied by varying the experimental parameters in order to achieve maximum degradation efficiency. The initial rate of degradation with TiO2/Hbeta was higher than with bare TiO2. TOC results revealed that TiO2 requires 600min for complete mineralization of propoxur whereas TiO2/Hbeta requires only 480min. TiO2/Hbeta showed enhanced photodegradation due to its high adsorption capacity on which the pollutant molecules are pooled closely and hence degraded effectively. 相似文献
10.
The photocatalytic oxidation of the azo dye Orange-II (Or-II) using Fe loaded TiO2 (Fe–TiO2) was studied under ultraviolet (UV), visible (vis) and simultaneous UV–vis irradiations using a solar light simulator. Photocatalysts were characterized by means of XRD, SEM-EDX, FTIR and DRS. Fe3+ species, identified in XPS analyses, were responsible of the increased absorption of visible light. Moreover, DRS analyses showed a decrease in the bandgap due to Fe3+ loading. Photocatalystic tests proved that Fe modification enhanced the TiO2 photocatalytic activity towards Or-II photodegradation under simultaneous UV–vis irradiation. Even so, the performance of the Fe–TiO2 samples towards the photodegradation of phenol, under UV irradiation, was lower than TiO2 suggesting the recombination of the UV photogenerated electron–hole pair. Therefore, results evidence a Fe3+ promotion of the electron caption in the photosensitization process of TiO2 by Or-II acting as a sensitizer. Such process leads to the Or-II photooxidation under UV–vis irradiation by losing energy in electron transferring processes to sensitize TiO2, and, the formation of reactive oxygen species promoted by the injected electron to the TiO2 conduction band. 相似文献
11.
The hollow spheres of anatase TiO2 with higher photocatalytic activity have been fabricated by spherical CaCO3 nanoparticles as a template, and titanium sulfate (Ti(SO4)2) as a precursor, and the CaCO3 templates were dissolved subsequently in dilute HNO3 solution. The TiO2 hollow spheres samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and N2 adsorption-desorption isotherms. The characterization results indicate that as prepared TiO2 hollow spheres sample was transformed to anatase phase in calcined at 400 °C, and the anatase TiO2 hollow spheres have a higher specific surface area and show much better photocatalytic activity than commercial P25 in the photodegradation of Rhodamine B under the UV irradiation. 相似文献
12.
Photocatalytic activity of TiO2 doped with boron and vanadium 总被引:2,自引:0,他引:2
Bettinelli M Dallacasa V Falcomer D Fornasiero P Gombac V Montini T Romanò L Speghini A 《Journal of hazardous materials》2007,146(3):529-534
Boron (B)- and vanadium (V)-doped TiO(2) photocatalysts were synthesized using modified sol-gel reaction processes and characterized by X-ray diffraction (XRD), Raman spectroscopy and N(2) physisorption (BET). The photocatalytic activities were evaluated by monitoring the degradation of methylene blue (MB). The results showed that the materials possess high surface area. The addition of B favored the transformation of anatase to rutile, while in the presence of V, anatase was the only phase detected. The MB degradation on V-doped TiO(2) was significantly affected by the preparation method. In fact while the presence of V in the bulk did not influence strongly the photoreactivity under visible irradiation, an increase of surface V doping lead to improved photodegradation of MB. The degradation of MB dye indicated that the photocatalytic activities of TiO(2) increased as the boron doping increased, with high conversion efficiency for 9mol% B doping. 相似文献
13.
Photocatalytic degradation of gaseous benzene over TiO2/Sr2CeO4: kinetic model and degradation mechanisms 总被引:1,自引:0,他引:1
Photocatalytic oxidation of benzene in air was carried out over TiO2/Sr2CeO4 catalysts. The prepared photocatalyst was characterized by SBET, UV-vis diffuse reflectance and XPS. TiO2/Sr2CeO4 absorbs much more visible light than TiO2 in the visible light region. The XPS spectrum shows that the binding energy value of Ti 2p3/2 transfers to a lower value. The main purpose was to investigate the kinetic model and degradation mechanisms. The kinetic data matched well with the Langmuir-Hinshelwood (L-H) kinetic model with the limiting rate constant and the adsorption constant in this case were 0.0064 mg l-1 min-1 and 9.2078 l mg-1, respectively. No gas-phase intermediates were detected by direct GC/FID analysis under the conditions despite the high benzene concentration. Ethyl acetate and (3-methyl-oxiran-2-yl)-methanol were two major identified intermediates which were accompanied by butylated hydroxytoluene, 2,6-bis(1,1-dimethylethyl)-4,4-dimethylycyclohe, 2,5-cyclohexadiene-1,4,dione,2,6-bis(1,1-dim). It is plausible that at least one of these less-reactive intermediates caused the deactivation of the photocatalyst. Finally, the photocatalytic oxidation mechanisms were speculated. 相似文献
14.
TiO2/SnO2 stacked-layers are synthesized by reactive sputter deposition on the glass substrate. Very thin TiO2/SnO2 bilayer-photocatalysts exhibited a very high photocatalytic activity for a degradation of gaseous acetaldehyde. Both the control of an electronic structure of TiO2 overlayer in the near-surface region and the interfacial separation of photogenerated electrons/holes in the TiO2/SnO2 stacked-layer are keys to improve the photocatalytic performance. 相似文献
15.
A series of titanium dioxide (TiO(2)/Ti) film electrodes were prepared from titanium (Ti) metal mesh by an improved anodic oxidation process and were further modified by photochemically depositing gold (Au) on the TiO(2) film surface as Au-TiO(2)/Ti film electrodes. The morphological characteristics, crystal structure and photoelectroreactivity of both the TiO(2)/Ti and Au-TiO(2)/Ti electrodes were studied. The experiments confirmed that the gold modification of TiO(2) film could enhance the efficiency of e(-)/h(+) separation on the TiO(2) conduction band and resulted in the higher photocatalytic (PC) and photoelectrocatalytic (PEC) activity under UV or visible illumination. To further enhance the TiO(2) PEC reaction, a reticulated vitreous carbon (RVC) electrode was applied in the same reaction system as the cathode to electrically generate H(2)O(2) in the aqueous solution. The experiments demonstrated that such a H(2)O(2)-assisted TiO(2) PEC reaction system could achieve a much better performance of BPA degradation in aqueous solution due to an interactive effect among TiO(2), Au, and H(2)O(2). It may have good potential for application in water and wastewater treatment in the future. 相似文献
16.
Liugang Wang ) Junying Zhang ) Chunzhi Li ) Hailing Zhu ) Wenwen Wang ) Tianmin Wang ) ) School of Physics Nuclear Energy Engineering Beihang University Beijing China ) Sh ong Provincial Key Laboratory of Multi-photon Entanglement Manipulation 《材料科学技术学报》2011,27(1):59-63
TiO2 film modified by Bi2O3 microgrid array was successfully fabricated by using a microsphere lithography method.The structure and morphology of TiO2 film,Bi2O3 film and TiO2 film/Bi2O3 microgrid heterojunction were characterized through X-ray diffraction,atomic force microscopy and scanning electron microscopy.The optical transmittance spectra and the photocatalytic degradation capacity of these samples to rhodamine B were determined via ultraviolet-visible spectroscopy.The results indicated that the coupled system showed higher photocatalytic activity than pure TiO2 and Bi2O3 films under xenon lamp irradiation.The enhancement of the photocatalytic activity was ascribed to the special structure,which could improve the separation of photo-generated electrons and holes,enlarge the surface area and extend the response range of TiO2 film from ultraviolet to visible region. 相似文献
17.
The photocatalytic degradation of indigo carmine has been investigated in aqueous solutions using TiO2 coated non-woven fibres as photocatalyst. The experiments were carried out to investigate the factors influencing the photocatalytic degradation, such as the previous adsorption in the dark, initial concentration of dye solution, temperature, and pH. The experimental results show that adsorption is an important parameter controlling the apparent kinetic constant of the degradation. The photocatalytic degradation rate was favoured by a high concentration of solution in respect to Langmuir-Hinshelwood model. The degradation rate was pH and temperature dependent with a high degradation rate at high temperature. 相似文献
18.
MgFe2O4/TiO2 (MFO/TiO2) composite photocatalysts were successfully synthesized using a mixing-annealing method. The synthesized composites exhibited significantly higher photocatalytic activity than a naked semiconductor in the photodegradation of Rhodamine B. Under UV and visible light irradiation, the optimal percentages of doped MgFe2O4 (MFO) were 2 wt.% and 3 wt.%, respectively. The effects of calcination temperature on photocatalytic activity were also investigated. The origin of the high level of activity was discussed based on the results of X-ray diffraction, UV-vis diffuse reflection spectroscopy, scanning electron microscopy, transmission electron microscopy, and nitrogen physical adsorption. The enhanced activity of the catalysts was mainly attributed to the synergetic effect between the two semiconductors, the band potential of which matched suitably. 相似文献
19.
近年来,石墨烯以其独特的结构和优异的性能成为材料科学领域备受关注的研究前沿和热点。由于石墨烯具有超高的载流子迁移率以及超大的比表面积,将石墨烯与传统的光催化材料复合可显著提高复合材料的光催化性能。综述了石墨烯/TiO2纳米复合材料的研究进展,重点阐述了石墨烯/TiO2纳米复合材料的制备方法及其在光催化领域中的应用,并指出石墨烯/TiO2纳米复合材料的光催化机理是今后研究的重点方向。 相似文献
20.
The present study investigates the dependence of photocatalytic rate on molecular structure of the substrate that is degraded. The photocatalytic degradation of Azure (A and B) and Sudan (III and IV) dyes, having similar structure, but different functional groups, were investigated with two catalysts. The photocatalytic activity of solution combustion synthesized TiO(2) (CS TiO(2)) was compared with that of Degussa P-25 for degrading these dyes. The effect of solvents and mixed-solvent system on photodegradation of Sudan III was investigated. The photodegradation rate was found to be higher in solvents with higher polarity. The effect of pH and the presence of metal ions in the form of chloride and nitrate salt, on degradation rate of Azure A was also investigated. The metal ions significantly reduced the photocatalysis rates. A detailed Langmuir-Hinshelwood kinetic model has been developed to explain the effect of metal ions on degradation rate of the substrate. This model elucidates the contribution of holes and electrons towards degradation of the dye. 相似文献