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1.
TiO 2-supported activated carbon felts (TiO 2–ACFTs) were prepared by dip coating of felts composed of activated carbon fibers (ACFs) with either polyester fibers (PS-A20) and/or a polyethylene pulp (PE-W15) in a TiO 2 aqueous suspension followed by calcination at 250 °C for 1 h. The as-prepared TiO 2–ACFTs with 29–35 wt.% TiO 2 were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and N 2 adsorption. The TiO 2–ACFT(PS-A20) samples with 0 and 29 wt.% TiO 2 were microporous with specific surface areas ( S BET) of 996 and 738 m 2/g, respectively, whereas the TiO 2–ACFT(PE-W15) samples with 0 and 35 wt.% TiO 2 were mesoporous with S BET of 826 and 586 m 2/g, respectively. Adsorption and photocatalytic activity of the as-prepared samples were evaluated by measuring adsorption in the dark and photodegradation of gaseous acetaldehyde (AcH) and methylene blue (MB) in aqueous solution under UV light. The TiO 2 loading caused a considerable decrease in the S BET and MB adsorption capacity along with an increase in MB photodegradation and AcH mineralization. Lemna minor was chosen as a representative aquatic plant for ecotoxicity tests measuring detoxification of water obtained from the MB photodegradation reaction with the TiO 2–ACFT samples under UV light. 相似文献
2.
Photocatalytic degradation of bisphenol A (BPA) in waters and wastewaters in the presence of titanium dioxide (TiO 2) was performed under different conditions. Suspensions of the TiO 2 were used to compare the degradation efficiency of BPA (20 mg L ?1) in batch and compound parabolic collector (CPC) reactors. A TiO 2 catalyst supported on glass spheres was prepared (sol–gel method) and used in a CPC solar pilot plant for the photodegradation of BPA (100 μg L ?1). The influence of OH·, O 2 ·?, and h + on the BPA degradation were evaluated. The radicals OH· and O 2 ·? were proved to be the main species involved on BPA photodegradation. Total organic carbon (TOC) and carboxylic acids were determined to evaluate the BPA mineralization during the photodegradation process. Some toxicological effects of BPA and its photoproducts on Eisenia andrei earthworms were evaluated. The results show that the optimal concentration of suspended TiO 2 to degrade BPA in batch or CPC reactors was 0.1 g L ?1. According to biological tests, the BPA LC 50 in 24 h for E. andrei was of 1.7?×?10 ?2 mg cm ?2. The photocatalytic degradation of BPA mediated by TiO 2 supported on glass spheres suffered strong influence of the water matrix. On real municipal wastewater treatment plant (MWWTP) secondary effluent, 30 % of BPA remains in solution; nevertheless, the method has the enormous advantage since it eliminates the need of catalyst removal step, reducing the cost of treatment. 相似文献
3.
Noble metal Ag-decorated, monodisperse TiO 2 aggregates were successfully synthesized by an ionic strength-assisted, simple sol–gel method and were used for the photocatalytic degradation of the antibiotic oxytetracycline (OTC) under both UV and visible light (UV–visible light) irradiation. The synthesized samples were characterized by X-ray diffraction analysis (XRD); UV–vis diffuse reflectance spectroscopy; environmental scanning electron microscopy (ESEM); transmission electron microscopy (TEM); high-resolution TEM (HR-TEM); micro-Raman, energy-dispersive X-ray spectroscopy (EDS); and inductively coupled plasma optical emission spectrometry (ICP-OES). The results showed that the uniformity of TiO 2 aggregates was finely tuned by the sol–gel method, and Ag was well decorated on the monodisperse TiO 2 aggregates. The absorption of the samples in the visible light region increased with increasing Ag loading that was proportional to the amount of Ag precursor added in the solution over the tested concentration range. The Brunauer, Emmett, and Teller (The BET) surface area slightly decreased with increasing Ag loading on the TiO 2 aggregates. Ag-decorated TiO 2 samples demonstrated enhanced photocatalytic activity for the degradation of OTC under UV–visible light illumination compared to that of pure TiO 2. The sample containing 1.9 wt% Ag showed the highest photocatalytic activity for the degradation of OTC under both UV–visible light and visible light illumination. During the experiments, the detected Ag leaching for the best TiO 2-Ag photocatalyst was much lower than the National Secondary Drinking Water Regulation for Ag limit (0.1 mg L ?1) issued by the US Environmental Protection Agency. 相似文献
4.
Photocatalytic process has shown recently a great potential as an environmental friendly and clean remediation technology for organic pollutants in wastewater. This work described the synthesis of silver-based bimetallic nanoparticles using colloid chemistry and the subsequent immobilization onto titania to form composite photocatalytic materials (titania-supported Ag–Pt nanoparticles). The photocatalysts were characterized by X-ray diffraction, electron microscopy, and nitrogen physisorption. The catalytic activity of the photocatalysts was evaluated by photocatalytic degradation of phenol and 2-chlorophenol (2-CP) in synthetic wastewater solutions. The photocatalytic processes were conducted in a batch photoreactor containing appropriate solutions of phenol and 2-CP with UV irradiation of 450 W. UV-visible spectrophotometer was used for analyzing the concentration of phenol and 2-CP in solutions. Parameters affecting the photocatalytic process such as the solution pH, phenol and 2-CP concentrations, and catalyst concentration were investigated. The results obtained revealed that TiO 2-supported Ag/Pt nanoparticles showed a higher activity for UV-photocatalytic degradation of both phenol and 2-CP pollutants in the solution (as compared to the plain rutile TiO 2). The photodegradation processes were optimized by the 0.5-g/L catalyst with a pollutant concentration of 50 mg/L for all the samples. Complete degradation for both phenol and 2-CP was achieved after 120 min. 相似文献
5.
This study investigated the photocatalytic degradation of acetaminophen (ACT) in synthetic titanium dioxide (TiO 2) solution under a visible light ( λ >440 nm). The TiO 2 photocatalyst used in this study was synthesized via sol–gel method and doped with potassium aluminum sulfate (KAl(SO 4) 2) and sodium aluminate (NaAlO 2). The influence of some parameters on the degradation of acetaminophen was examined, such as initial pH, photocatalyst dosage, and initial ACT concentration. The optimal operational conditions were also determined. Results showed that synthetic TiO 2 catalysts presented mainly as anatase phase and no rutile phase was observed. The results of photocatalytic degradation showed that LED alone degraded negligible amount of ACT but with the presence of TiO 2/KAl(SO 4) 2, 95 % removal of 0.10-mM acetaminophen in 540-min irradiation time was achieved. The synthetic TiO 2/KAl(SO 4) 2 presented better photocatalytic degradation of acetaminophen than commercially available Degussa P-25. The weak crystallinity of synthesized TiO 2/NaAlO 2 photocatalyst showed low photocatalytic degradation than TiO 2/KAl(SO 4) 2. The optimal operational conditions were obtained in pH 6.9 with a dose of 1.0 g/L TiO 2/KAl(SO 4) 2 at 30 °C. Kinetic study illustrated that photocatalytic degradation of acetaminophen fits well in the pseudo-first order model. Competitive reactions from intermediates affected the degradation rate of ACT, and were more obvious as the initial ACT concentration increased. 相似文献
6.
The aqueous photodegradation of fluopyram was investigated under UV light ( λ?≥?200 nm) and simulated sunlight irradiation ( λ?≥?290 nm). The effect of solution pH, fulvic acids (FA), nitrate (NO 3 ?), Fe (III) ions, and titanium dioxide (TiO 2) on direct photolysis of fluopyram was explored. The results showed that fluopyram photodegradation was faster in neutral solution than that in acidic and alkaline solutions. The presence of FA, NO 3 ?, Fe (III), and TiO 2 slightly affected the photodegradation of fluopyram under UV irradiation, whereas the photodegradation rates of fluopyram with 5 mg L ?1 Fe (III) and 500 mg L ?1 TiO 2 were about 7-fold and 13-fold faster than that without Fe (III) and TiO 2 under simulated sunlight irradiation, respectively. Three typical products for direct photolysis of fluopyram have been isolated and characterized by liquid chromatography tandem mass spectrometry. These products resulted from the intramolecular elimination of HCl, hydroxyl-substitution, and hydrogen extraction. Based on the identified transformation products and evolution profile, a plausible degradation pathway for the direct photolysis of fluopyram in aqueous solution was proposed. In addition, acute toxicity assays using the Vibrio fischeri bacteria test indicated that the transformation products were more toxic than the parent compound. 相似文献
7.
Abstract The present work deals with photocatalytic degradation of an organophosphorus pesticide, phosalone, in water in the presence of TiO 2 particles under UV light illumination (1000 W). The influence of the basic photocatalytic parameters such as pH of the solution, amount of TiO 2, irradiation time, stirring rate, and distance from UV source, on the photodegradation efficiency of phosalone was investigated. The degradation rate of phosalone was not high when the photolysis was carried out in the absence of TiO 2 and it was negligible in the absence of UV light. The half-life (DT 50) of a 20 ppm aqueous solution of phosalone was 15 min in optimized conditions. The plot of lnC (phosalone) vs. time was linear, suggesting first order reaction ( K = 0.0532 min ?1). The half-life time of photomineralization in the concentration range of 7.5–20 ppm was 13.02 min. The efficiency of the method was also determined by measuring the reduction of Chemical Oxygen Demand (COD). During the mineralization under optimized conditions, COD decreased by more than 45% at irradiation time of 15 min. The photodegradation of phosalone was enhanced by addition of proper amount of hydrogen peroxide (150 ppm). 相似文献
8.
In the present study, the photocatalytic degradation of Reactive Red 195 (RR195) from aqueous samples under UV-A irradiation by using anatase/brookite TiO 2 (A/B TiO 2) mesoporous nanoparticles has been investigated. Batch experiments were conducted to study the effects of the main parameters affecting the photocatalytic process. The effects and interactions of most influenced parameters, such as substrate concentration and catalyst load, were evaluated and optimized by using a central composite design model and a response surface methodology. The results indicated that the dye degradation efficiency in the experimental domain investigated was mainly affected by the tested variables, as well as their interaction effects. Analysis of variance showed a high coefficient of determination value ( R 2?=?0.9947), thus ensuring a satisfactory adjustment of the first-order regression model (2FI model) with the experimental data. The obtained results also indicate that catalyst loading plays an important role in determining the removal efficiency of RR195 attributable to both photodegradation and adsorption process. Under optimal conditions (initial dye concentration (50 mg/L) and catalyst loading (2,000 mg/L), A/B TiO 2 showed similar removal efficiency compared to that of commercial titania (Degussa P25). Also, at these conditions, complete degradation of RR195 can be achieved by both catalysts within 15 min under UV-A irradiation. The experiments demonstrated that dye removal on the prepared A/B TiO 2 was facilitated by the synergistic effects between adsorption and photocatalysis. Photocatalytic mineralization of RR195 was monitored by total organic carbon. The recycling experiments confirmed the stability of the catalyst. 相似文献
9.
This paper demonstrated the relative bactericidal activity of photoirradiated (6W-UV Torch, λ?>?340 nm and intensity?=?0.64 mW/cm 2) P25–TiO 2 nanoparticles, nanorods, and nanotubes for the killing of Gram-negative bacterium Agrobacterium tumefaciens LBA4404 for the first time. TiO 2 nanorod (anatase) with length of 70–100 nm and diameter of 10–12 nm, and TiO 2 nanotube with length of 90–110 nm and diameter of 9–11 nm were prepared from P-25 Degussa TiO 2 (size, 30–50 nm) by hydrothermal method and compared their biocidal activity both in aqueous slurry and thin films. The mode of bacterial cell decomposition was analyzed through transmission electron microscopy (TEM), Fourier transform-infrared (FT-IR), and K + ion leakage. The antimicrobial activity of photoirradiated TiO 2 of different shapes was found to be in the order P25–TiO 2?>?nanorod?>?nanotube which is reverse to their specific surface area as 54?<?79?<?176 m 2 g ?1, evidencing that the highest activity of P25–TiO 2 nanoparticles is not due to surface area as their crystal structure and surface morphology are entirely different. TiO 2 thin films always exhibited less photoactivity as compared to its aqueous suspension under similar conditions of cell viability test. The changes in the bacterial surface morphology by UV-irradiated P25–TiO 2 nanoparticles was examined by TEM, oxidative degradation of cell components such as proteins, carbohydrates, phospholipids, nucleic acids by FT-IR spectral analysis, and K + ion leakage (2.5 ppm as compared to 0.4 ppm for control culture) as a measure of loss in cell membrane permeability. 相似文献
10.
The present work mainly deals with photocatalytic degradation of a herbicide, erioglaucine, in water in the presence of TiO 2 nanoparticles (Degussa P-25) under ultraviolet (UV) light illumination (30 W). The degradation rate of erioglaucine was not so high when the photolysis was carried out in the absence of TiO 2 and it was negligible in the absence of UV light. We have studied the influence of the basic photocatalytic parameters such as pH of the solution, amount of TiO 2, irradiation time and initial concentration of erioglaucine on the photodegradation efficiency of erioglaucine. A kinetic model is applied for the photocatalytic oxidation by the UV/TiO 2 system. Experimental results indicated that the photocatalytic degradation process could be explained in terms of the Langmuir–Hinshelwood kinetic model. The values of the adsorption equilibrium constant, K, and the second order kinetic rate constant, k, were 0.116 ppm ? 1 and 0.984 ppm min ? 1, respectively. In this work, we also compared the reactivity between the commercial TiO 2 Degussa P-25 and a rutile TiO 2. The photocatalytic activities of both photocatalysts were tested using the herbicide solution. We have noticed that photodegradation efficiency was different between both of them. The higher photoactivity of Degussa P-25 compared to that of rutile TiO 2 for the photodegradation of erioglaucine may be due to higher hydroxyl content, higher surface area, nano-size and crystallinity of the Degussa P-25. Our results also showed that the UV/TiO 2 process with Degussa P-25 as photocatalyst was appropriate as the effective treatment method for removal of erioglaucine from a real wastewater. The electrical energy consumption per order of magnitude for photocatalytic degradation of erioglaucine was lower with Degussa P-25 than in the presence of rutile TiO 2. 相似文献
11.
This study reports the synthesis and characterization of composite nitrogen and fluorine co-doped titanium dioxide (NF-TiO 2) for the removal of contaminants of concern in wastewater under visible and solar light. Monodisperse anatase TiO 2 nanoparticles of different sizes and Evonik P25 were assembled to immobilized NF-TiO 2 by direct incorporation into the sol–gel or by the layer-by-layer technique. The composite films were characterized with X-ray diffraction, high-resolution transmission electron microscopy, environmental scanning electron microscopy, and porosimetry analysis. The photocatalytic degradation of atrazine, carbamazepine, and caffeine was evaluated in a synthetic water solution and in an effluent from a hybrid biological concentrator reactor (BCR). Minor aggregation and improved distribution of monodisperse titania particles was obtained with NF-TiO 2-monodisperse (10 and 50 nm) from the layer-by-layer technique than with NF-TiO 2?+?monodisperse TiO 2 (300 nm) directly incorporated into the sol. The photocatalysts synthesized with the layer-by-layer method achieved significantly higher degradation rates in contrast with NF-TiO 2-monodisperse titania (300 nm) and slightly faster values when compared with NF-TiO 2-P25. Using NF-TiO 2 layer-by-layer with monodisperse TiO 2 (50 nm) under solar light irradiation, the respective degradation rates in synthetic water and BCR effluent were 14.6 and 9.5?×?10 ?3?min ?1 for caffeine, 12.5 and 9.0?×?10 ?3?min ?1 for carbamazepine, and 10.9 and 5.8?×?10 ?3?min ?1 for atrazine. These results suggest that the layer-by-layer technique is a promising method for the synthesis of composite TiO 2-based films compared to the direct addition of nanoparticles into the sol. 相似文献
12.
Heterogeneous photocatalysis is highlighted to treat volatile organic compound (VOC) emission. Then, this work analysed the influence of palladium (Pd) content loaded in TiO2 on n-octane and iso-octane photodegradation. For this, TiO2 was loaded with Pd in different contents: 0.4%, 0.7%, and 1.0%. The samples were characterized, and the photodegradation experiments were conducted by Pd/TiO2/UV process. The characterization analyses showed that the metal presence did not change the catalyst structure or its surface area; however, it reduced the bandgap energy. The photocatalytic results proved that palladium improved n-octane degradation from 62% (pure TiO2) to 92.6% (0.4%Pd/TiO2) and, iso-octane degradation enhanced from 59% (pure TiO2) to 90.6% (0.7%Pd/TiO2); all results were obtained in the space time of 39 s. Therefore, 0.4%Pd/TiO2 and 0.7%Pd/TiO2 showed better oxidation results to degradation n-octane and iso-octane, respectively. The kinetic model of pseudo-first order showed a good fit for the data of both VOCs. Heterogeneous photocatalysis with Pd/TiO2 showed to be an adequate technique to reduce VOCs emission. 相似文献
13.
Carbofuran (CBF) removal in a continuous-flow photocatalytic reactor with granular activated carbon supported titanium dioxide (GAC-TiO 2) catalyst was investigated. The effects of feed flow rate, TiO 2 concentration and addition of supplementary oxidants on CBF removal were investigated. The central composite design (CCD) was used to design the experiments and to estimate the effects of feed flow rate and TiO 2 concentration on CBF removal. The outcome of CCD experiments demonstrated that reactor performance was influenced mainly by feed flow rate compared to TiO 2 concentration. A second-order polynomial model developed based on CCD experiments fitted the experimental data with good correlation ( R2 ~ 0.964). The addition of 1 mL min ?1 hydrogen peroxide has shown complete CBF degradation and 76% chemical oxygen demand removal under the following operating conditions of CBF ~50 mg L ?1, TiO 2 ~5 mg L ?1 and feed flow rate ~82.5 mL min ?1. Rate constant of the photodegradation process was also calculated by applying the kinetic data in pseudo-first-order kinetics. Four major degradation intermediates of CBF were identified using GC-MS analysis. As a whole, the reactor system and GAC-TiO 2 catalyst used could be constructive in cost-effective CBF removal with no impact to receiving environment through getaway of photocatalyst. 相似文献
14.
The decomposition of highly toxic chemical warfare agent, sulfur mustard (bis(2-chloroethyl) sulfide or HD), has been studied by homogeneous photolysis and heterogeneous photocatalytic degradation on titania nanoparticles. Direct photolysis degradation of HD with irradiation system was investigated. The photocatalytic degradation of HD was investigated in the presence of TiO 2 nanoparticles and polyoxometalates embedded in titania nanoparticles in liquid phase at room temperature (33?±?2 °C). Degradation products during the treatment were identified by gas chromatography–mass spectrometry. Whereas apparent first-order kinetics of ultraviolet (UV) photolysis were slow (0.0091 min ?1), the highest degradation rate is obtained in the presence of TiO 2 nanoparticles as nanophotocatalyst. Simultaneous photolysis and photocatalysis under the full UV radiation leads to HD complete destruction in 3 h. No degradation products observed in the presence of nanophotocatalyst without irradiation in 3 h. It was found that up to 90 % of agent was decomposed under of UV irradiation without TiO 2, in 6 h. The decontamination mechanisms are often quite complex and multiple mechanisms can be operable such as hydrolysis, oxidation, and elimination. By simultaneously carrying out photolysis and photocatalysis in hexane, we have succeeded in achieving faster HD decontamination after 90 min with low catalyst loading. TiO 2 nanoparticles proved to be a superior photocatalyst under UV irradiation for HD decontamination. 相似文献
15.
BiVO 4/TiO 2 composites with different weight ratios have been prepared by coprecipitation-based reactions followed by either thermal or hydrothermal treatment with the aim of evaluating the TiO 2 photosensitization by BiVO 4. The obtained materials present in all cases the desired monoclinic phase of BiVO 4 and anatase phase of TiO 2. Visible light absorption increased with increasing amount of bismuth vanadate. XPS results reveal the surface enrichment of Ti with respect to the bulk composition in samples characterised by a higher content of BiVO 4. The photocatalytic activity of the prepared materials was tested for the degradation of isopropanol in the gas phase under indoor illumination conditions. Although none of the composites was able to improve the activity of TiO 2, the low BiVO 4 containing samples appear as more suitable for further synthesis tuning. 相似文献
16.
The influences of HCO 3 ?, Cl ?, and other components on the UV/TiO 2 degradation of the antineoplastic agents ifosfamide (IFO) and cyclophosphamide (CP) were studied in this work. The results indicated that the presence of HCO 3 ?, Cl ?, NO 3 ?, and SO 4 2? in water bodies resulted in lower degradation efficiencies. The half-lives of IFO and CP were 1.2 and 1.1 min and increased 2.3–7.3 and 3.2–6.3 times, respectively, in the presence of the four anions (initial compound concentration = 100 μg/L, TiO 2 loading =100 mg/L, anion concentration = 1000 mg/L, and pH = 8). Although the presence of HCO 3 ? in the UV/TiO 2/HCO 3 ? system resulted in a lower degradation rate and less byproduct formation for IFO and CP, two newly identified byproducts, P11 (M.W. = 197) and P12 (M.W. = 101), were formed and detected, suggesting that additional pathways occurred during the reaction of ?CO 3 ? in the system. The results also showed that ?CO 3 ? likely induces a preferred ketonization pathway. Besides the inorganic anions HCO 3 ?, Cl ?, NO 3 ?, and SO 4 2?, the existence of dissolved organic matter in the water has a significant effect and inhibits CP degradation. Toxicity tests showed that higher toxicity occurred in the presence of HCO 3 ? or Cl ? during UV/TiO 2 treatment and within 6 h of reaction time, implying that the effects of these two anions should not be ignored when photocatalytic treatment is applied to treat real wastewater. 相似文献
17.
Textile dye effluents are typically characterized by strong color and recalcitrance, even at very low concentration. The process of enrichment of anionic azo dye on the surface of TiO 2 fibers followed by photosensitization degradation under ambient air conditions was extensively investigated. Adsorption isotherms and zeta potentials were used to describe the “dye/TiO 2 surface” interface, taking into account the effects of pH on the nature and population of the surface groups on the TiO 2 fibers. The extent of the photocatalytic degradation of dye on TiO 2 surface was determined by FTIR. N 2 adsorption isotherms and optical spectra were employed to investigate the effect of photosensitization. The adsorption of dyes on the TiO 2 surface occurs via electrostatic attraction through the formation of single- or multidentate-coordinated surface complexes. Almost complete photobleaching of the absorption band at 534 nm is achieved in ~4 h. Dye-sensitized TiO 2 fiber could absorb part of the visible light spectrum ( λ?<?600 nm). Interfacial electron transfer can potentially alter the degradation efficiency. The regenerated TiO 2 fiber could be reused for subsequent decolorization without a decline in adsorption efficiency compared with freshly prepared TiO 2 samples, which may be attributed to preservation of the hierarchical pore structure and restoration of the original surface properties. In summary, we propose an efficient “adsorption–photoregeneration–reuse” process applying TiO 2 fibers for the degradation of dyes in water. 相似文献
18.
The anatase/schorl composites were prepared and employed for the photocatalytic discoloration of an azo dye, Methyl Orange (MO). X-ray diffraction results indicated that TiO 2 existed in the form of anatase phase and no diffraction peaks of schorl could be observed for all the composite samples. Scanning electron micrographs showed that the particles of anatase were well deposited and dispersed on the surface of schorl. Photocatalytic experiments revealed that the anatase/schorl composites exhibited higher photocatalytic activity for MO discoloration than pure TiO 2 and more than 90 % discoloration ratio could be obtained within 60 min UV irradiation when the sample containing 3 wt.% of schorl as TiO 2 support was used. Then, the central composite design (CCD) under the response surface methodology (RSM) was employed for the experiment design and process optimization. The significance of a second-order polynomial model for predicting the optimal values of MO discoloration was evaluated by the analysis of variance (ANOVA) and 3D response surface plots for the interactions between two variables were constructed. Based on the model prediction, the optimum conditions for the photocatalytic discoloration of MO by TiO 2/schorl composite were determined to be 15?×?10 ?3 mM MO initial concentration, 2.7 g/l photocatalyst dosage, solution pH 6.6 and 43 min reaction time, with a maximum MO discoloration ratio of 98.6 %. Finally, a discoloration ratio of 94.3 % was achieved for the real sample under the optimum conditions, which was very close to the predicted value, implying that RSM is a powerful and satisfactory strategy for the process optimization. 相似文献
19.
以硫酸钛为原料,采用共沉淀法,制备了一系列纳米二氧化钛复合石墨烯催化剂,采用XRD和FTIR对样品进行表征。通过紫外光照射亚甲基蓝溶液光催化降解实验,研究石墨烯的加入量对TiO2光催化性能的影响,结果表明,TiO2-GO-5具有最佳的光催化性能。在pH=6.00、TiO2-GO-5的投加量为0.070 g/50 mL、光照3 h条件下,100 mg/L亚甲基蓝溶液的脱色率达到最大值为90.52%。 相似文献
20.
1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (or p,p′-DDT) is one of the most persistent pesticides. It is resistant to breakdown in nature and cause the water contamination problem. In this work, a major objective was to demonstrate the application of N-doped TiO 2 in degradation and mineralization of the p,p′-DDT under UV and visible light in aqueous solution. The N-doped TiO 2 nanopowders were prepared by a simple modified sol–gel procedure using diethanolamine (DEA) as a nitrogen source. The catalyst characteristics were investigated using XRD, SEM, TEM, and XPS. The adsorption and photocatalytic oxidation of p,p′-DDT using the synthesized N-doped TiO 2 under UV and visible light were conducted in a batch photocatalytic experiment. The kinetics and p,p′-DDT degradation performance of the N-doped TiO 2 were evaluated. Results show that the N-doped TiO 2 can degrade p,p′-DDT effectively under both UV and visible lights. The rate constant of the p,p′-DDT degradation under UV light was only 0.0121 min ?1, whereas the rate constant of the p,p′-DDT degradation under visible light was 0.1282 min ?1. Under visible light, the 100% degradation of p,p′-DDT were obtained from N-doped TiO 2 catalyst. The reaction rate of p,p′-DDT degradation using N-doped TiO 2 under visible light was sixfold higher than that under UV light. According to Langmuir-Hinshelwood model, the adsorption equilibrium constant (K) for the N-doped TiO 2 under visible light was 0.03078 L mg ?1, and the apparent reaction rate constant (k) was 1.3941 mg L ?1-min. Major intermediates detected during the p,p′-DDT degradation were p,p′-DDE, o,p′-DDE, p,p′-DDD and p,p′-DDD. Results from this work can be applied further for the breakdown of p,p′-DDT molecule in the real contaminated water using this technology. 相似文献
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