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1.
A new type of photodegradable poly(vinyl chloride)‐bismuth oxyiodide/TiO2 (PVC‐BiOI/TiO2) nanocomposite film was prepared by embedding a nano‐TiO2 photocatalyst modified by BiOI into the commercial PVC plastic. The solid‐phase photocatalytic degradation behavior of the as‐prepared film was investigated in ambient air at room temperature under UV light irradiation, with the aid of UV‐Vis spectroscopy, weight loss monitoring, scanning electron microscopy, and FT‐IR spectroscopy. Compared to the PVC‐TiO2 nanocomposite film, the PVC‐BiOI nanocomposite film and the pure PVC film, the PVC‐BiOI/TiO2 nanocomposite film exhibited a higher photocatalytic degradation activity. The optimal mass ratio of BiOI to TiO2 was found to be 0.75 %. The weight loss rate of the PVC‐BiOI/TiO2 nanocomposite film reached 30.8 % after 336 h of irradiation, which is 1.5 times higher than that of the PVC‐TiO2 nanocomposite film under identical conditions. The solid‐phase photocatalytic degradation mechanism of the nanocomposite films was briefly discussed.  相似文献   

2.
A novel photodegradable TiO2‐Fe(St)3‐polystyrene (TiO2‐Fe(St)3‐PS) nanocomposite was prepared by embedding TiO2 and Fe(St)3 into the commercial polystyrene. Ferric stearate was added into polymer as cocatalyst in order to improve the dispersion in polystyrene and photocatalytic efficiency of TiO2 nanoparticles. Solid‐phase photocatalytic degradation of the TiO2‐Fe(St)3‐PS nanocomposite was carried out in an ambient air at room temperature under ultraviolet lamp. The properties of TiO2‐Fe(St)3‐PS composite film were compared with that of the pure PS film and the TiO2‐PS composite film, through weight loss monitoring, scanning electron microscope, gel permeation chromatogram, and FTIR spectroscopy. The photodegradation efficiency of TiO2‐Fe(St)3‐PS composite film was higher than that of the pure PS film and the TiO2‐PS composite film under the UV light irradiation. The average molecular weight (Mw) of TiO2‐Fe(St)3‐PS composite film decreased 63.08%, and the number of average molecular weight (Mn) decreased 79.49% after UV light irradiation for 480 h. Photo‐oxidation leads to an increase in the low molecular weight fraction by chain scission, thereby facilitating biodegradation. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

3.
BACKGROUND: Nanoparticulate titanium dioxide (TiO2) has the advantages of high chemical stability, high photocatalytic activity to oxidise pollutants in air and water, relatively low price and non‐toxicity. However, its high surface energy leads to the aggregation of nanoparticles. In addition, the wide band gap of TiO2 (3.2 eV) only allows it to absorb ultraviolet (UV) light (<387 nm), which represents just a small fraction (3–5%) of the solar photons. These factors have limited its use in many fields. In this study, nanoparticulate TiO2 was modified by polyaniline (PANI) in order to enhance its photoactivity under UV light and sunlight illumination. RESULTS: TiO2 nanoparticles were modified by PANI via a chemical oxidative method. The introduction of small amounts of PANI enhanced the dispersion of TiO2 nanoparticles and improved the photocatalytic activity under UV light. In addition, the band gap energies of all PANI/TiO2 nanocomposites were lower than that of neat TiO2 nanoparticles, so the PANI/TiO2 nanocomposites can be excited to produce more electron–hole pairs under sunlight, which could result in higher photocatalytic activities. CONCLUSION: The modification of nanoparticulate TiO2 by PANI can increase its photoactivity in the process of phenol degradation under UV light and sunlight illumination. Copyright © 2008 Society of Chemical Industry  相似文献   

4.
Polyaniline/nano‐TiO2 composites with the content of nano‐TiO2 varying from 6.2 wt % to 24.1 wt % were prepared by using solid‐state synthesis method at room temperature. The structure and morphology of the composites were characterized by the Fourier transform infrared (FTIR) spectra, ultraviolet‐visible (UV–vis) absorption spectra, X‐ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The electrochemical performances of the composites were investigated by galvanostatic charge–discharge measurement, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results from FTIR and UV–vis spectra showed that the composites displayed higher oxidation and doping degree than pure PANI. The XRD and morphological studies revealed that the inclusion of nano‐TiO2 particles hampered the crystallization of PANI chains in composites, and the composites exhibited mixed particles from free PANI particles and the nano‐TiO2 entrapped PANI particles. The galvanostatic charge–discharge measurements indicated that the PANI/nano‐TiO2 composites had higher specific capacitances than PANI. The composite with 6.2 wt % TiO2 had the highest specific capacitance among the composites. The further electrochemical tests on the composite electrode with 6.2 wt % TiO2 showed that the composite displayed an ideal capacitive behavior and good rate ability. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

5.
BACKGROUND: Semiconductor TiO2 has been investigated extensively due to its chemical stability, nontoxicity and inexpensiveness. However, the wide band gap of anatase TiO2 (about 3.2 eV) only allows it to absorb UV light. TiO2 nanoparticles modified by conditional conjugated polymers show excellent photocatalytic activity under visible light. However, these conjugated polymers are not only expensive, but also difficult to process. Polyvinyl chloride (PVC) was heat‐treated at high temperature to remove HCl and a C?C conjugated chain structure was obtained. When TiO2 nanoparticles were dispersed into the conjugated polymer film derived from PVC, this composites film exhibited high visible light photocatalytic activity. RESULTS: The photocatalytic activity of TiO2/heat‐treated PVC (HTPVC) film was investigated by degrading Rhodamine B (RhB) under visible light irradiation. The photodegradation of RhB follows apparent first‐order kinetics. The rate constants of RhB photodegradation in the presence of the TiO2/HTPVC films with different mass content of TiO2 are 16–56 and 4–14 times that obtained in the presence of the pure HTPVC and TiO2/polymethyl methacrylate (PMMA) composite film, respectively. The TiO2/HTPVC film showed excellent photocatalytic activity and stability after 10 cycles under visible light irradiation. CONCLUSION: TiO2/HTPVC film exhibits high visible light photocatalytic activity and stability. Copyright © 2012 Society of Chemical Industry  相似文献   

6.
BACKGROUND: Mercury electrodeless discharge lamps (Hg‐EDLs) were used to generate UV radiation when exposed to a microwave field. EDLs were coated with doped TiO2 in the form of thin films containing transition metal ions Mn+ (M = Fe, Co, Ni, V, Cr, Mn, Zr, Ag). Photocatalytic degradation of mono‐chloroacetic acid (MCAA) to HCl, CO2, and H2O, and decomposition of Rhodamine B on the thin films were investigated in detail. RESULTS: Polycrystalline thin doped TiO2 films were prepared by dip‐coating of EDL via a sol–gel method using titanium n‐butoxide, acetylacetone, and a transition metal acetylacetonate. The films were characterized by Raman spectroscopy, UV/Vis absorption spectroscopy, X‐ray photoelectron spectroscopy (XPS), electron microprobe analysis and by atomic force microscopy (AFM). The photocatalytic activity of doped TiO2 films was monitored in the decomposition of Rhodamine B in water. Compared with the pure TiO2 film, the UV/Vis spectra of V, Zr and Ag‐doped TiO2 showed significant absorption in the visible region, and hence the photocatalytic degradation of MCAA had increased. The best apparent degradation rate constant (0.0125 min?1), which was higher than that on the pure TiO2 film by a factor of 1.7, was obtained with the Ag(3%)/TiO2 photocatalyst. The effect of doping level of vanadium acetylacetonate on the photocatalytic efficiency of the V‐doped TiO2 was determined. CONCLUSIONS: Transition metal ion‐doped TiO2 thin films showed significant absorption in the visible region. The metal doped TiO2 photocatalyst (with an appropriate amount of V, Zr and Ag) on the Hg‐EDLs increased the degradation efficiency of MCAA in a microwave field. Copyright © 2009 Society of Chemical Industry  相似文献   

7.
《Journal of Catalysis》2006,237(2):393-404
The photocatalytic reaction of nitric oxide (NO) on TiO2 and transition metal-loaded M (Cu, V, and Cr)/TiO2 catalysts was studied using in situ FTIR spectroscopy under UV irradiation. TiO2 and M/TiO2 catalysts were prepared by the sol–gel method via controlled hydrolysis of titanium (IV) butoxide. Copper, vanadium, or chromium was loaded onto TiO2 during the sol–gel procedure. After treatment at 500 °C under air flow, a large amount of surface peroxo species and OH groups were detected on the TiO2 and M/TiO2 catalysts. Nitric oxide was adsorbed on TiO2 and M/TiO2 in the form of bidentate nitrites and nitrates by reacting with OH groups, peroxo, or MO species. In addition, NO can also be adsorbed on Mn+ in the form of nitrosyls. Under UV irradiation, bidentate nitrite was oxidized to either monodentate or bidentate nitrate. Such oxidation was suggested to be induced by superoxo species generated by oxidizing peroxo species via photogenerated holes. The existence of nitrosyls deferred the oxidation of nitrites to nitrates due to the prior oxidation of nitrosyls by superoxo. The XRD and UV–vis spectra showed that the structures and the abilities of absorbing UV light of all catalysts were not influenced by the photocatalytic NO reaction. Possible mechanisms were proposed for the photocatalytic NO oxidation on TiO2 and M/TiO2 based on the intermediates found from the in situ FTIR study.  相似文献   

8.
In this study, low‐density polyethylene (LDPE) nanocomposite films with two types of nanoparticles, TiO2 (3 wt %) and Closite 20A (3 and 5 wt %), were prepared using a melt blow extrusion as an industrial method and their properties such as mechanical properties, water vapor, oxygen and carbon dioxide gas barrier, and antimicrobial activity were tested. Transmission electron microscopy (TEM) and X‐ray diffraction (XRD) were also performed to determine the degree of dispersion and exfoliation of nanoparticles. Mechanical test indicated that the reinforcement in the presence of the nanocomposites was more than that with their conventional counterparts, and the highest stiffness was achieved in a sample containing 5 wt % clay and 3 wt % TiO2. Exfoliation of silicate layers and a good dispersion of TiO2 nanoparticles in LDPE were achieved as confirmed by XRD and TEM. The gas barrier properties were improved after formation of the nanocomposites especially by insertion of 5 wt % of clay nanoparticles as a filler in the LDPE matrix. The photocatalytic effect of the nanocomposite film was carried out by antimicrobial evaluation against Pseudomonas spp. and Rhodotorula mucilaginosa and by ethylene removal test using 8 W ultraviolet (UV) lamps with a constant relative intensity of 1 mW cm?2. The greatest effects were recorded by combining UVA illumination and active film. It was also proven that the photocatalyst thin film with improved barrier properties prepared by extrusion could be used in horticultural product packaging applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41764.  相似文献   

9.
A photocatalyst, TiO2?xNy/AC (activated carbon (AC) supported N‐doped TiO2), highly active in both the Vis and UV range, was prepared by calcination of the TiO2 precursor prepared by acid‐catalyzed hydrolysis in an ammonia atmosphere. The powders were characterized by diffuse reflectance spectroscopy, scanning electron microscopy, X‐ray diffraction, N2 adsorption, Fourier transform infrared spectroscopy and phenol degradation. The doped N in the TiO2 crystal lattice creates an electron‐occupied intra‐band gap allowing electron‐hole pair generation under Vis irradiation (500–560 nm). The TiO2?xNy/AC exhibited high levels of activity and the same activity trends for phenol degradation under both Vis and UV irradiation: TiO2?xNy/AC calcined at 500 °C for 4 h exhibited the highest activity. The band‐gap level newly formed by doped N can act as a center for the photo‐generated holes and is beneficial for the UV activity enhancement. The performance of the prepared TiO2?xNy/AC photocatalyst revealed its practical potential in the field of solar photocatalytic degradation of aqueous contaminants. Copyright © 2007 Society of Chemical Industry  相似文献   

10.
A photocatalytic activity ultrafiltration membrane (UFM) was prepared by the blending of a poly(vinylidene fluoride) (PVDF) polymer with mesoporous titanium dioxide (M‐TiO2) particles via the phase‐inversion method. The microstructure of the membrane and Ti element distribution were characterized by scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Their properties were also determined by thermogravimetric analysis, differential scanning calorimetry, Fourier transform infrared spectroscopy, tensile stress tests, contact angle tests, bovine serum albumin retention, water flux, and permeation flux. When the M‐TiO2 concentration reached 1 wt %, the thermal stability, mechanical properties, hydrophilicity, flux, and antifouling performance of the M‐TiO2/PVDF UFM were improved to an optimal value with the M‐TiO2 particles successfully entrapped and evenly distributed throughout the PVDF polymer matrix. Compared with the P25‐modified PVDF UFM (1 wt %), the M‐TiO2‐modified PVDF UFM (1 wt %) exhibited better photocatalytic activity and wonderful stability in the UV photocatalytic degradation of the organic dye Rhodamine B. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43427.  相似文献   

11.
To enhance the photocatalytic activity of TiO2, V and Zn co-doped TiO2 films were synthesized by the sol–gel method. The experimental results indicated that the films were composed of round-like nano-particles or aggregates. V and Zn codoping could not only obviously increase the specific surface area of TiO2 but also result in the narrowed band gap of TiO2 sample. The photocatalytic activities of the TiO2 films were evaluated by the photocatalytic decomposition of organic dyes in aqueous solution. Compared with un-doped TiO2 film or single doped TiO2 film, V and Zn co-doped TiO2 film exhibited excellent photocatalytic activities under both UV light and visible light. The improvement mechanism by V and Zn codoping was also discussed.  相似文献   

12.
In this study, silver‐ or copper‐doped TiO2–Ce‐, TiO2–La‐, and commercial TiO2 (P25)‐supported catalysts were prepared. The catalysts and supports were characterised by powder X‐ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption studies. UV‐light‐assisted heterogeneous Fenton‐like oxidation of two different‐structure dyes (anionic azo dye Orange II, CI Acid Orange 7 and cationic triphenylmethane dye Crystal Violet, CI Basic Violet 3) was investigated over the catalysts. Higher catalytic activity was observed in the oxidation of Orange II than in the oxidation of Crystal Violet. For both dyes, the TiO2–Ce and TiO2–La‐supported catalysts, which were in the form of anatase only, gave higher photocatalytic activity than the P25‐supported catalysts, which were in the form of anatase and rutile. Complete colour removal was observed during oxidation of Orange II over Cu/TiO2–Ce and Cu/TiO2–La catalysts, whereas the highest degree of decolorisation, 89.3%, was achieved by oxidation of Crystal Violet over Ag/TiO2–Ce. The pH of the solution affected the surface state of the TiO2, thus affecting the photocatalytic degradation of the dyes. The surface area of the catalysts is also a key parameter that influences their photocatalytic activity. It was observed that catalysts having higher surface areas brought about greater dye degradation.  相似文献   

13.
Conducting polyaniline (PANI)/titanium dioxide (TiO2) composite nanofibres with an average diameter of 80–100 nm were prepared by one‐step in situ polymerization method in the presence of anatase nano‐TiO2 particles, and were characterized via Fourier‐transform infrared spectra, UV/vis spectra, wide‐angle X‐ray diffraction, thermogravimetric analysis, and transmission electron microscopy, as well as conductivity and cyclic voltammetry. The formation mechanism of PANI/TiO2 composite nanofibres was also discussed. This composite contained ~ 65% conducting PANI by mass, with a conductivity of 1.42 S cm?1 at 25°C, and the conductivity of control PANI was 2.4 S cm?1 at 25°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

14.
A novel photodegradable and biodegradable polyethylene (PE) film was prepared through a melt blending technique, where nano‐TiO2 and common kaolin were used as the photocatalyst and biodegradable promoter showing improved degradable efficiency of the waste PE. The photo‐degradation of the composite film was investigated by weight loss monitoring, attenuated total reflection–fourier transformed infrared spectroscopy (ATR–FTIR), and scanning electron microscopy. The aerobic biodegradation of the residue films after photodegradation was investigated by analysis of evolved carbon dioxide of films in aquatic test systems according to the international standards (ISO 14852, 1999). The results showed that the weight loss of as‐prepared photo‐ and biodegradable composite film reached 26.8% after 240 h of UV light irradiation. The big cavities formed not only on the film surface but also inside the bulk film, together with the chalking phenomenon taking place. The biodegradation results revealed that the addition of kaolin enhanced the degradation of UV‐light treated TiO2‐PE films. The prepared PE based composite films showed promising application as novel photo‐biodegradable environment‐harmless materials. In addition, a degradation mechanism for this composite film was also discussed. POLYM. COMPOS., 37:2353–2359, 2016. © 2015 Society of Plastics Engineers  相似文献   

15.
Anatase TiO2‐modified flower‐like Bi2WO6 nanostructures were prepared by a simple hydrothermal reaction followed by layer‐by‐layer deposition and calcination. The photocatalytic activity was evaluated using Brilliant Red X3B, an anionic azo dye, as the target organic pollutant under UV‐Vis light irradiation. The experiment results showed that the photocatalytic activity of the hybrid increases first and then decreases with increasing loading amount of TiO2. The hybrid coated with four layers of TiO2 (containing 20 wt‐% TiO2) showed the highest photocatalytic activity, which is 10.45 and 3.20 times higher than that of pure Bi2WO6 and TiO2, respectively. The improved photocatalytic performance of TiO2‐modified Bi2WO6 nanostructures could be ascribed to the improved light‐harvesting ability, efficient photo‐generated electron‐hole separation, and enhanced adsorption of the dye. This work may shed light on the design of complex architectures and the exploitation of their potential applications.  相似文献   

16.
TiO2 thin films were fabricated through hydrothermal method. Silver nanoparticles were loaded on TiO2 thin films via photoreduction technique. Subsequently, the graphene quantum dots (GQDs) were spin‐coated on the Ag/TiO2 nanocomposites thin films. The crystal structure, surface morphology and UV‐vis absorbance were tested by XRD, SEM and ultraviolet‐visible spectrophotometer. These results indicated that Ag nanoparticles and GQDs are anchored on the TiO2 nanorods. Absorbance of Ag/TiO2 and GQDs/Ag/TiO2 nanocomposite thin films have been extended into the visible region. Visible‐light response of the samples were investigated by electrochemical workstation. The photoresponse of the sample can be enhanced by sensitization of the Ag nanoparticles and GQDs. The enhanced visible‐light response may be due to the surface plasmon resonance of silver nanoparticles and visible absorbance of GQDs. The highest photocatalytic activity has been observed in the 9‐GQDs/Ag/TiO2 composite thin film. The efficient charge separation and transportation can be achieved by introducing the Ag nanoparticles and GQDs in the TiO2 thin film.  相似文献   

17.
S–N co-doped anatase nanosized TiO2 photocatalyst was successfully prepared by simple sol–gel method. The samples were characterized by XRD, XPS, UV–Vis. From the results of UV–Vis, a red shift of the absorption edge was brought out owing to the S and N codoping. XPS and UV–Vis studies revealed that N and S were in situ codoped in the lattice of TiO2 and the absorbance in visible light region decreased with the calcination temperature increased. The photocatalytic activity was evaluated by the photocatalytic oxidation of penicillin solution under visible light irradiation. The results show that visible-light induced photocatalytic activities of the as-prepared TiO2 powders were improved by S–N copoing. The high activity of S–N co-doped TiO2 can be related to the results of the synergetic effects of strong absorption in the UV–Vis region, red shift in adsorption edge.  相似文献   

18.
A pulse current deposition technique was adopted to construct highly dispersed Ag nanoparticles on TiO2 nanotube arrays which were prepared by the electrochemical anodization. The morphology, crystallinity, elemental composition, and UV-vis absorption of Ag/TiO2 nanotube arrays were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and diffuse reflectance spectra (DRS). In particular, the photoelectrochemical properties and photoelectrocatalytic activity under UV light irradiation and the photocatalytic activity under visible light irradiation for newly synthesized Ag/TiO2 nanotube arrays were investigated. The maximum incident photon to charge carrier efficiency (IPCE) value of Ag/TiO2 nanotube arrays was 51%, much higher than that of pure TiO2 nanotube arrays. Ag/TiO2 nanotube arrays exhibited higher photocatalytic activities than the pure TiO2 nanotube arrays under both UV and visible light irradiation. The photoelectrocatalytic activity of Ag/TiO2 nanotube arrays under UV light irradiation was 1.6-fold enhancement compared with pure TiO2 nanotube arrays. This approach can be used in synthesizing various metal-loaded nanotube arrays materials.  相似文献   

19.
The photocatalytic oxidation of 4‐methoxybenzyl alcohol to p‐anisaldehyde (PAA) was performed in water with organic‐free suspensions of home‐prepared and commercial titanium dioxide (TiO2) catalysts. The nanostructured TiO2 samples were synthesised by boiling aqueous solutions of titanium tetrachloride (TiCl4), under mild conditions, for different times. The crystallinity increased with the boiling time. The 4‐methoxybenzyl alcohol oxidation rate followed the same pattern but the highest yield (41.5 % mol) to PAA was found for the least crystalline sample, that showed a quantum efficiency of 0.116 %. A comparison with two commercial TiO2 samples showed that all the home‐prepared catalysts exhibited a PAA yield higher than that of commercial ones. The only by‐products present were traces of 4‐methoxybenzoic acid and aliphatic products, carbon dioxide being the other main oxidation product.  相似文献   

20.
Using electrospinning, specially prepared Ti and Sr precursor TiO2/SrTiO3 composite nanofibers were successfully fabricated. This would ensure the close and uniform contact between TiO2 and SrTiO3, which significantly contributes to the electrons transfer at the interface between the two semiconductors with different band gaps. Meanwhile, the long fibrous structure of TiO2/SrTiO3 composite nanofibers would further ease the electron transfer, enlarge the specific surface area, and enhance the light absorption capability thus leading to the improvement of photocatalytic efficiency. Because of the above‐mentioned advantages, the TiO2/SrTiO3 composite nanofibers exhibited higher photocatalytic H2 generation efficiency over bare TiO2 nanofibers in a water/methanol sacrificial reagent system under the irradiation of UV light.  相似文献   

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