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1.
ZnS-loaded TiO 2 (ZnS–TiO 2) was synthesized by a sol–gel method. The catalyst was characterized by using different techniques (XRD, HR-SEM, EDS, DRS, PL, XPS, and BET methods). The photocatalytic activity of ZnS–TiO 2 was investigated for the degradation of Sunset Yellow FCF (SY) dye in an aqueous solution using ultraviolet light. ZnS–TiO 2 is found to be more efficient than prepared TiO 2, TiO 2–P25, TiO 2 (Merck), and ZnS at pH 7 for the mineralization of SY. The effects of operational parameters such as the amount of photocatalyst, dye concentration, and initial pH on photo mineralization of SY have been analyzed. The mineralization of SY has been confirmed by chemical oxygen demand measurements. The catalyst is found to be reusable. 相似文献
2.
Photocatalytic membranes reactors have become one of the most efficient technologies to treat polluted waters. However, a major drawback is the unilateral irradiation of the membrane, where only one side of the membrane is exploited. To overcome this issue, we developed a reactor where the membrane can be irradiated on both sides. Polyacrylonitrile membranes containing different amounts of TiO2 nanoparticles up to 60% were first prepared by electrospinning. These membranes were used in a 3D-printed crossflow photocatalytic membrane reactor for the degradation of methylene blue under different combinations of lights. The use of both sides of the photocatalytic membrane significantly enhanced the photocatalytic activity for the decolorization of methylene blue in water. The prepared membranes showed the best decolorization rate for a loading of 60% of TiO2 and the use of dual ultraviolet lights, where the methylene blue solution was completely discolored after 90 min. This is the first report of a such system configuration, and this new irradiation concept is promising for photocatalytic membrane reactions and water cleaning. 相似文献
3.
Multi-walled carbon nanotubes (MWCNTs)/TiO 2 composite photocatalysts with high photoactivity were prepared by sol-gel process and further characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR), and UV-vis absorption spectra. Compared to pure TiO 2, the combination of MWCNTs with titania could cause a significant absorption shift toward the visible region. The photocatalytic performances of the MWCNTs/TiO 2 composite catalysts were evaluated for the decomposition of Reactive light yellow K-6G (K-6G) and Mordant black 7 (MB 7) azo dyes solution under solar light irradiation. The results showed that the addition of MWCNTs enhanced the adsorption and photocatalytic activity of TiO 2 for the degradation of azo dyes K-6G and MB 7. The effect of MWCNTs content, catalyst dosage, pH, and initial dye concentration were examined as operational parameters. The kinetics of photocatalytic degradation of two dyes was found to follow a pseudo-first-order rate law. The photocatalyst was used for seven cycles with photocatalytic degradation efficiency still higher than 98%. A plausible mechanism is also proposed and discussed on the basis of experimental results. 相似文献
4.
The photocatalytic degradation of the herbicide isoproturon under solar light was investigated in aqueous solution containing a Bi–TiO 2/zeolite photocatalyst. The catalysts were characterized using X-ray diffraction, UV-Vis diffuse reflectance spectroscopy, Fourier transform-infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The effect of Bi–TiO 2 loading onto the zeolite support and influence of the parameters such as catalyst amount, pH, and initial concentration of isoproturon on the degradation rate were evaluated. The recycling ability of the catalyst was found to be sustainable for elongated periods. The high activity of the Bi–TiO 2/zeolite was attributed to its absorptivity of visible light and its high adsorption capacity for the pollutant molecules. 相似文献
5.
Photocatalytic oxidation using semiconductors is one of the advanced oxidation processes for degradation of organic pollutants in water and air. TiO 2 is an excellent photocatalyst that can mineralize a large range of organic pollutants such as pesticides and dyes. The main challenge is to improve the efficiency of the TiO 2 photocatalyst and to extend TiO 2 light absorption spectra to the visible region. A potential solution is to couple TiO 2 with a narrow band gap semiconductor possessing a higher conduction band such as bismuth oxide. Therefore, here we prepared Bi 2O 3/TiO 2 heterojunctions by the impregnation method with different Bi/Ti ratio. The prepared composites have been characterized by UV–Vis diffused reflectance spectra and X-ray diffraction. The photocatalytic activity of the heterojunction has been determined from the degradation of orange II under visible and UV light. Results show that Bi 2O 3/TiO 2 heterojunctions are more effective than pure TiO 2-anatase under UV-A irradiation, with an optimum for the Bi/Ti ratio of 5 %, for the photocatalytic degradation of Orange II. However, the photocatalytic activity under irradiation at λ higher than 420 nm is not much improved. Under UV–visible radiation, the two semiconductors are activated. We propose a mechanism explaining why our products are more effective under UV–visible irradiation. In this case the charge separation is enhanced because a part of photogenerated electrons from the conduction band of TiO 2 will go to the conduction band of bismuth oxide. In this composite, titanium dioxide is the main photocatalyst, while bismuth oxide acts as adsorbent photosensitizer under visible light. 相似文献
6.
BackgroundIn this study, the photodegradation of three pharmaceuticals, namely Ibuprofen (IBP), Naproxen (NPX), and Cetirizine (CIZ) in aqueous media was investigated under UV irradiation. The photocatalyst used in this work consists of surface functionalized titanium dioxide (TiO2–NH2) nanoparticles grafted into Polyacrylonitrile (PAN)/multi-walled carbon nanotube composite nanofibers. Surface modification of the fabricated composite nanofibers was illustrated using XRD, FTIR, and SEM analyses.ResultsSets of experiments were performed to study the effect of pharmaceuticals initial concentration (5–50 mg/L), solution pH (2–9), and irradiation time on the degradation efficiency. The results demonstrated that more than 99% degradation efficiency was obtained for IBP, CIZ, and NPX within 120, 40, and 25 min, respectively.ConclusionsComparatively, the photocatalytic degradation of pharmaceuticals using PAN-CNT/TiO2–NH2 composite nanofibers was much more efficient than with PAN/TiO2–NH2 composite nanofibers. 相似文献
7.
The synthesis of silver doped nano-particulate titanium dioxide (Ag/TiO 2) using a microemulsion method and an investigation of its photocatalytic activity for the degradation of Acid Red 27 in distilled water under UV-irradiation is reported. The prepared Ag/TiO 2 is characterized using transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The size of the Ag nanoparticles is around 5–15?nm, with almost uniform distribution on the TiO 2 particles. The efficiency of the photocatalytic process is evaluated to establish the optimum conditions, found to be at 2?wt% of Ag loading on TiO 2, catalyst dosage of 400?mg?L ?1, and calcination temperature of 300°C. Complete decolorization of the dye solution on Ag/TiO 2 was observed in 20?min of UV irradiation in the optimum conditions. 相似文献
8.
The results of a study of photocatalytic degradation of phenol using aqueous oxygenated TiO 2 (anatase) suspensions in a batch Pyrex photoreactor are reported. The influence on the photodegradation rate of various parameters as pH, phenol and TiO 2 content, oxygen partial pressure, anions present in the dispersions was investigated. A complete oxidation of phenol was observed. Intermediate compounds, catechol and quinone, were detected. It was observed that the photodegradation also proceeded with sunlight radiation. A mechanistic and kinetic model, which accounts for the results obtained, is given. Likely reasons for inactivity of the rutile modification for this reaction are also given. 相似文献
9.
ZnO/TiO 2 composites were synthesized by using the solvothermal method and ultrasonic precipitation followed by heat treatment in order to investigate their photocatalytic degradation of methyl orange (MO) in aqueous suspension under UV irradiation. The composition and surface structure of the catalyst were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and transmission electron microscopy (TEM). The degradation efficiencies of MO at various pH values were obtained. The highest degradation efficiencies were obtained before 30 min and after 60 min at pH 11.0 and pH 2.0, respectively. A sample analysis was conducted using liquid chromatography coupled with electrospray ionization ion-trap mass spectrometry. Six intermediates were found during the photocatalytic degradation process of quinonoid MO. The degradation pathway of quinonoid MO was also proposed. 相似文献
10.
The photocatalytic degradation of Procion blue H-B dye in biodegraded textile washwater has been investigated for the complete removal of color and maximum reduction of chemical oxygen demand (COD). Pseudomonas putida was utilized for obtaining biodegraded textile washwater. In this process, silver-doped TiO 2 photocatalyst was prepared and experiments were carried out to study the effects of UV and mercury lamp irradiations on COD reduction and removal of color. The thus prepared silver-doped TiO 2 catalyst was characterized by thermogravimetric and differential thermal analysis, UV-visible spectrometer, X-ray diffraction, scanning electron microscope, energy dispersive X-ray microanalysis, and BET surface area techniques. Adsorption studies were also carried out to evaluate the fitness of isotherm models. The results show that the silver-doped TiO 2 has enhanced the photodegradation of Procion blue H-B dye under UV and mercury lamp irradiations. The enhanced activity of silver-doped TiO 2 is due to the enrichment of electron–hole separation by electron trapping of silver particles. 相似文献
11.
In this study, kinetics of photocatalytic degradation of phenolic wastewater in immobilized photocatalytic reactor was investigated. Immobilization of titanium dioxide (TiO 2) nano powders on concrete surfaces were accomplished with epoxy concrete sealer. Kinetics of photocatalytic reactions has been proposed to follow the Langmuir–Hinshelwood model in different initial phenol concentration, pH, and UV lamp intensity. First-order reaction kinetics with respect to the pollutant concentration was obtained for the reaction. Effect of UV lamp intensity showed that kinetic constants were proportional to the power of 0.73–1 of the photonic flow. In all cases kinetic constant increases as pH of the system reached up to 12 units. Several reaction intermediates were identified using the GC/Mass analysis. Products at the initial stage of the reaction were aromatic compounds, contained hydroquinone, benzoquinone, and catechol. These intermediates underwent further photocatalytic oxidation to aliphatic compounds and finally into CO 2 and H 2O after 4?h. Kinetic constants of intermediate compounds were determined using mathematical–chemical equations and nonlinear regression. Data showed that the differences between the mathematical model and Langmuir–Hinshelwood model for the kinetic constant was less than 5%. 相似文献
12.
光降解反应中为了有效地利用可见光,以氨水为氮源,采用溶胶凝胶法在温和条件下制备出黄色氮掺杂二氧化钛。分别采用XRD、TEM、XPS和UV-Vis漫反射光谱对样品进行了表征。结果表明,所制备的样品均为锐钛矿相,晶粒随N/Ti配比的增加而增大;氮掺杂进入二氧化钛晶格中使可见光吸收增强。为控制水处理过程中的气味问题,以巯基苯并噻唑为探针,考察了氮掺杂二氧化钛的可见光活性。结果显示氮掺杂二氧化钛在可见光照射下可使巯基苯并噻唑的降解率为商用二氧化钛DegussaP-25的3倍。此外,存在一个最佳N/Ti配比显示出最高的可见光活性。 相似文献
13.
The TiO 2/SiO 2 composite was prepared by means of the SiO 2-particle-entrapment method. The FTIR data showed the presence of Si–O–Ti stretching vibration band at 970 cm −1 in the TiO 2/SiO 2 composite, suggesting a reaction between TiO 2 and silica on the TiO 2 particle surface during the silicagel formation around the TiO 2 particles. The photocatalytic efficiency of TiO 2 immobilized in silicagel was compared with that of the conventional TiO 2 Degussa P25 catalyst. For this purpose, the degradation of indigo carmin (IC) dye was used as model molecule in the tests.
The effect of operational parameters such as catalyst loading and dye concentration on the photocatalytic degradation of the
model dye was investigated. The rate of degradation increased with increasing catalyst loading, and when the concentration
of the dye decreases. 相似文献
14.
The photodegradation of aqueous solutions containing 0.2 mM methyl parathion has been studied through the optimization of
the [H 2O 2]/[Fe 3+] ratio in a Fe 3+/H 2O 2/UV-C flow system of 1.3 L capacity. The decay kinetics and TOC abatement have been analyzed for the experiments performed
at pH 3.0 and room temperature. All experiments lead to the total methyl parathion destruction after a few minutes, following
a pseudo-first-order decay kinetics. Total mineralization can be reached after 120 min at the optimum ratio found, due to
the synergistic effect of the very oxidizing hydroxyl radical ( ·OH) produced via the Fenton reagent and the effective photodecarboxylation at 253.7 nm. 相似文献
15.
The aim of our research is to apply experimental design methodology to the optimization of photocatalytic degradation of indole
present in wastewater. Heterogeneous photocatalysis for the oxidation of organic biorecalcitrant pollutants in water is an
environmental promising method. We used the response surface methodology (RSM) for the modelization and optimization of the
photodegradation of indole in the presence of titanium dioxide. The effect of indole concentration, UV intensity and stirring
speed on the yield of indole degradation was determined. According to the mathematic optimization of the process, the optimum
point when 100% of degradation is achieved is given by the following values: UV intensity = 250 W/m 2, stirring speed = 536.36 tr/min and initial indole concentration = 10.10 mg/l. 相似文献
16.
The photocatalytic activity of TiO 2 deposits (Degussa P25 and Millennium PC500) has been studied using sulfamethoxazole (SMX) as a model water pollutant and a UV fluorescent lamp as a light source (365 nm). Both catalysts have shown very similar properties in the photocatalytic degradation of SMX. Special attention has been given to the effect of the irradiation time, pH, and pollutant concentration. No mass-transfer limitations are observed. The degradation of SMX is accelerated at low concentration, and the photocatalytic degradation kinetics obey the Langmuir–Hinshelwood model, allowing the adsorption and apparent rate constants to be determined for both catalysts. 相似文献
17.
The photocatalytic degradation of diazinon was studied over TiO 2 catalysts. The kinetics obtained demonstrated that powder titania (t 1/2 = 9.7 min) was more efficient compared to pure titania thin film catalysts (t 1/2 = 29.4 min). Mineralization of organic carbon to CO 2 after 360 min of irradiation was found to be 75% while heteroatoms (P, S, N) were mineralized into phosphate, sulfate and
nitrate ions, respectively. A microtox test was performed to evaluate the toxicity of solutions treated by catalysts. Illumination
of diazinon in the presence of TiO 2 gave rise to several intermediates that have been identified by means of solid phase extraction and gas chromatography-mass
spectrometry, while a simple degradation pathway is proposed. 相似文献
18.
以磷钨酸H3PW12O4(PW12)为光催化剂,异丙醇(IS)作为电子给体,研究阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)对PW12光催化还原降解直接耐晒黑G(DB19)的影响.考察了CTAB浓度、pH值、DB19初始浓度等因素对反应的影响,并采用一级反应动力学对反应过程进行分析.结果表明CTAB增强了PW12对直接耐晒黑G的还原脱色作用,CTAB浓度增加,DB19的光催化脱色速率提高.PW12用量对DB19还原脱色的影响程度和趋势与溶液中CTAB浓度有关,当CTAB浓度为0.10 mmol.L-1时,DB19的脱色速率随PW12用量的增加而增加;CTAB浓度为0.05 mmol.L-1,PW12用量为200 mg.L-1时DB19的脱色速率最快,继续增加反而降低.DB19还原脱色速率随其初始浓度升高而降低.另外,通过循环伏安法和暗反应明确还原态杂多蓝对染料的还原脱色作用,并借助UV-Vis光谱研究DB19、PW12、CTAB之间的相互作用,探索CTAB对PW12/IS光催化还原降解DB19的作用机理.该研究结果表明阳离子表面活性剂CTAB能够增强偶氮染料废水的PW12催化还原脱色处理. 相似文献
19.
Bi 2WO 6 was synthesized with a hydrothermal method at different pHs and used for the degradation of tetracycline (TC) in water. The mesoporous Bi 2WO 6 prepared at pH 1 (BWO-1) displayed the highest adsorption and degradation capacity to TC due to its large surface area and more efficient capacity to separate photogenerated electrons and holes. 97% of TC at 20 mg·L ?1 was removed by BWO-1 at 0.5 g·L ?1 after 120 min irradiation under simulated solar light. Only 31% of the total organic carbon (TOC) was removed after 360 min irradiation although the TC removal reached 100%, suggesting that TC was mainly transformed to intermediate products rather than completely mineralized. The intermediates were identified by high-performance liquid chromatography-time of flight-mass spectrometry (HPLC-TOF-MS) and possible photodegradation pathways were proposed. 相似文献
20.
Bisphenol A is an endocrine disruptor. Complete mineralization of bisphenol A is therefore a primary environmental issue.
Here, the combination of ozonation and photocatalysis by TiO 2 is proposed for the degradation and final mineralization of bisphenol A. TiO 2 films deposited onto two sides of an Al lamina show good stability and high surface roughness. We used a specific experimental
setup employing two facing ultraviolet lamps and TiO 2 layers, together with an ozone flux. High-performance liquid chromatography–mass spectrometry determinations on bisphenol
A solutions sampled at different reaction times and Fourier Transform Infrared analyses of the oxide at the end of the reaction
were performed to study the reaction intermediates and the overall degradation mechanism. Our results show that pollutant
mineralization achieved with the combined method is far higher, of 55% in the case of 0.3 mM bisphenol A, than those obtained
by individual treatments such as photolysis (<3%), ozonation (6%), photocatalysis (6%), and by other combined processes: photolytic
ozonation (13%) and catalytic ozonation (15%). This finding is explained by the occurrence of highly synergistic effects. 相似文献
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