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1.
A novel non-toxic hybrid BiVO4-GO-TiO2-polyaniline (PANI) (BVGT-PANI) composite with superior photocatalysis was successfully prepared via a one-pot hydrothermal reaction. The structural and morphological characterizations of the synthesized compounds were analyzed by a series of techniques. We found excellent photocatalytic efficiencies for methylene blue (MB) and phenol degradation under visible light irradiation after adhering the PANI to the photocatalyst. The degradation rates of MB and phenol reach up to approximately 85% and 80%, respectively, after 3 h of irradiation. For photodegradation MB, BVGTA exhibit the highest kapp rate constant of about 1.06?×?10?2 min?1, which is about 1.63-fold faster than BVG and 2.94-fold faster than BVGT. For photodegradation of phenol, BVGTA exhibits the highest kapp rate constant, of about 8.86?×?10?3min?1, which is about 1.2-fold faster than BVG and 1.96-fold faster than BVGT. Furthermore, vitro toxicity test against Bacillus subtilis and Staphylococcus aureus demonstrated that the nanophotocatalyst is non-toxic. 相似文献
2.
In this work, Bi 4Nb xTa (1−x)O 8I photocatalysts have been synthesized by solid state reaction method and characterized by powder X-ray diffraction, scanning electron microscope and UV-Vis near infrared diffuse reflectance spectroscopy. The photocatalytic activity of these photocatalysts was evaluated by the degradation of methyl orange (MO) in aqueous solutions under visible light, UV light and solar irradiation. The effects of catalyst dosage, initial pH and MO concentration on the removal efficiency were studied, and the photocatalytic reaction kinetics of MO degradation as well. The results indicated that Bi 4Nb xTa (1−x)O 8I exhibited high photocatalytic activity for the removal of MO in aqueous solutions. For example, the removal efficiency of MO by Bi 4Nb 0.1Ta 0.9O 8I was as high as 92% within 12 h visible light irradiation under the optimal conditions: initial MO concentration of 5-10 mg L −1, catalyst dosage of 6 g L −1 and natural pH (6-8), the MO molecules could be completely degradated by Bi 4Nb 0.1Ta 0.9O 8I within 40 min under UV light irradiation, and the photodegradation efficiency reaches to 60% after 7 h solar irradiation. Furthermore, the photocatalytic degradation of Bisphenol A (BPA) was also investigated under visible light irradiation. It is found that 99% BPA could be mineralized by Bi 4Nb 0.1Ta 0.9O 8I after 16 h visible light irradiation. Through HPLC/MS, BOD, TOC, UV-Vis measurements, we determined possible degradation products of MO and BPA. The results indicated that MO was degradated into products which are easier to be biodegradable and innocuous treated, and BPA could be mineralized completely. Furthermore, the possibility for the photosensitization effect in the degradation process of MO under visible light irradiation has been excluded. 相似文献
3.
Water pollution caused by the discharged insolubility petroleum contaminants and organic compound dyes seriously threatens the natural self-purity capacity of the water body and the survival of aquatic species, so it is imperative to restraint the deterioration of the aquatic environment. In this paper, pathways are propounded for the simultaneous removal of insoluble spilling oil and organic dye contaminants. Particularly, hydrophobic ZnSnO3 after stearic acid modification and Bi2MoO6 photocatalysts are introduced into the cotton fabric substrate through solution dip-coating. The durability of the prepared fabric suffers from the acid–base corrosion, thermal treatment and mechanical wear, while still exhibiting remarkable water-repellent (WCA?>?150°) property. Furthermore, the remarkable photocatalytic activity makes it possible for reusable degradation and the primary active species, namely the holes, to be verified by the radicals-capturing experiment. It is worth observing that as-prepared superhydrophobic fabric possesses admirable water-proof property and cycling durability of decomposing toxic water-soluble organic dye, thereby contributing to further realizing the ecological concept of clear waters. 相似文献
4.
Bacillus sp. CL18 was investigated to propose a bioprocess for protease production using feathers as organic substrate. In feather broth (FB), containing feathers as sole organic substrate (1–100 g l?1), maximal protease production was observed at 30 g l?1 (FB30) after 6 days of cultivation, whereas increased feather concentrations negatively affected protease production and feather degradation. Protease production peaks were always observed earlier during cultivations than maximal feather degradation. In FB30, 80% of initial feathers mass were degraded after 7 days. Addition of glucose, sucrose, starch, yeast extract (2 g l?1), CaCl2, or MgCl2 (10 mmol l?1) to FB30 decreased protease production and feather degradation. FB30 supplementation with NH4Cl (1 g l?1) resulted in less apparent negative effects on protease production, whereas peptone (2 g l?1) increased protease yields earlier during cultivations (3 days). Through a central composite design employed to investigate the effects of peptone and NH4Cl (0.5–4.5 g l?1) on protease production and feather degradation, FB30 supplementation with peptone and NH4Cl (0.5–1.1 g l?1) increased protease production within a shorter cultivation time (5 days) and hastened complete feather degradation (6 days). Feather bioconversion concurs with sustainable production of value-added products. 相似文献
5.
以光催化效果为评价标准,采用超声波作用下水解法制备Bi 2O 3/TiO 2复合光催化剂,考察了水解条件和Bi 2O 3掺入量等制备条件对复合光催化剂性能的影响。结果表明,与传统制备方法相比,该方法操作简单、快速;当水和乙醇的比例为4∶1时所得样品的光催化活性最好;Bi 2O 3的掺入拓宽了TiO 2对光的吸收范围,提高了TiO 2的光催化活性,掺入量(Bi 2O 3)为0.25%复合光催化剂催化活性最高;复合光催化剂对多种水溶性染料均具有较好的处理效果。 相似文献
6.
Bench-scale experiments have been conducted to evaluate a series of titania-supported Pt-Pd (as oxides) catalysts in the presence and absence of MoO 3 and Fe 2O 3 additives for their effectiveness in the complete catalytic oxidation of volatile organic compounds (VOCs) in air likely to be found in waste gases. Under oxidizing conditions, all of the catalysts promoted the complete oxidation of VOCs to CO 2 and H 2O. 99 % Conversion was achieved with a C 2H 4-C 2H 6 gas mixture in air at temperatures between about 160–450 °C and at a space velocity of 20,000 h ?1. Oxidation activity for the titania supported catalysts were found to decrease in the order Pt-Pd-Mo-Fe > Pt-Pd-Mo > Pt-Pd-Fe > Pt-Pd. However, the addition of MoO 3 and Fe 2O 3 increase the catalyst activity and reduce the reaction temperature for the complete destruction. Ageing was also performed in order to study the stability of the most active catalyst. Pt-Pd-Mo-Fe (as oxides) on titania catalyst is effective in oxidizing a wide range of volatile organic compounds at relatively low temperatures (220–405 °C) and and at a space velocity of 40,000 h ?1 and is resistant to poisoning by halogenated and amine volatile organic compounds. 相似文献
7.
In the present study, photocatalytic reactions of nitrogen oxides (NO x = NO + NO 2) were studied on commercial TiO 2 doped facade paints in a flow tube photoreactor under simulated atmospheric conditions. Fast photocatalytic conversion of NO and NO 2 was observed only for the photocatalytic paints and not for non-catalytic reference paints. Nitrous acid (HONO) was formed in the dark on all paints studied, however, it efficiently decomposes under irradiation only on the photocatalytic samples. Thus, it is concluded that photocatalytic paint surfaces do not represent a daytime source of HONO, in contrast to other recent studies on pure TiO 2 surfaces. As main final product, the formation of adsorbed nitric acid/nitrate anion (HNO 3/NO 3?) was observed with near to unity yield. In addition, traces of H 2O 2 were observed in the gas phase only in the presence of O 2. Formation of the greenhouse gas nitrous oxide (N 2O) could be excluded. The uptake kinetics of NO, NO 2 and HONO was very fast under atmospheric conditions (e.g. γ(NO + TiO 2) > 10 ?5). Thus, the uptake on urban surfaces (painted houses, etc.) will be limited by transport. For a hypothetically painted street canyon, an average reduction of nitrogen oxide levels of ca. 5% is estimated. Since the harmful HNO 3/NO 3? is formed on the surface of the photoactive paints, whereas it is formed in the gas phase in the atmosphere, the use of photocatalytic paints may also help to reduce acid deposition, e.g. on plants, or nitric acid related health issues. 相似文献
8.
A novel photocatalytic reactor for wastewater treatment was designed and constructed. The main part of the reactor was an aluminum tube in which 12 stainless steel circular baffles and four quartz tube were placed inside of the reactor like shell and tube heat exchangers. Four UV–C lamps were housed within the space of the quartz tubes. Surface of the baffles was coated with TiO 2. A simple method was employed for TiO 2 immobilization, while the characterization of the supported photocatalyst was based on the results obtained through performing some common analytical methods such as X-ray diffraction (XRD), scanning electron microscope (SEM), and BET. Phenol was selected as a model pollutant. A solution of a known initial concentration (20, 60, and 100 ppmv) was introduced to the reactor. The reactor also has a recycle flow to make turbulent flow inside of the reactor. The selected recycle flow rate was 7?×?10 ?5 m 3.s ?1, while the flow rate of feed was 2.53?×?10 ?7, 7.56?×?10 ?7, and 1.26?×?10 ?6 m 3.s ?1, respectively. To evaluate performance of the reactor, response surface methodology was employed. A four-factor three-level Box–Behnken design was developed to evaluate the reactor performance for degradation of phenol. Effects of phenol inlet concentration (20–100 ppmv), pH (3–9), liquid flow rate (2.53?×?10 ?7?1.26?×?10 ?6 m 3.s ?1), and TiO 2 loading (8.8–17.6 g.m ?2) were analyzed with this method. The adjusted R 2 value (0.9936) was in close agreement with that of corresponding R 2 value (0.9961). The maximum predicted degradation of phenol was 75.50 % at the optimum processing conditions (initial phenol concentration of 20 ppmv, pH?~?6.41, and flow rate of 2.53?×?10 ?7 m 3.s ?1 and catalyst loading of 17.6 g.m ?2). Experimental degradation of phenol determined at the optimum conditions was 73.7 %. XRD patterns and SEM images at the optimum conditions revealed that crystal size is approximately 25 nm and TiO 2 nanoparticles with visible agglomerates distribute densely and uniformly over the surface of stainless steel substrate. BET specific surface area of immobilized TiO 2 was 47.2 and 45.8 m 2 g ?1 before and after the experiments, respectively. Reduction in TOC content, after steady state condition, showed that maximum phenol decomposition occurred at neutral condition (pH?~?6). Figure The schematic view of the experimental set-up 相似文献
9.
Photocatalytic degradation of the herbicide, pendimethalin (PM) was investigated with BaTiO 3/TiO 2 UV light system in the presence of peroxide and persulphate species in aqueous medium. The nanoparticles of BaTiO 3 and TiO 2 were obtained by gel to crystallite conversion method. These photo catalysts are characterized by energy dispersive x-ray analysis (EDX), scanning electron microscope (SEM), x-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) adsorption isotherm and reflectance spectral studies. The quantum yields for TiO 2 and BaTiO 3 for the degradation reactions are 3.166 Einstein m ?2 s ?1 and 2.729 Einstein m ?2 s ?1 and catalytic efficiencies are 6.0444 × 10 ?7 mg ?2h ?1L 2 and 5.403 × 10 ?7 mg ?2h ?1L 2, respectively as calculated from experimental results. BaTiO 3 exhibited comparable photocatalytic efficiency in the degradation of pendimethalin as the most widely used TiO 2 photocatalyst. The persulphate played an important role in enhancing the rate of degradation of pendimethalin when compared to hydrogen peroxide. The degradation process of pendimethalin followed the first-order kinetics and it is in agreement with Langmuir-Hinshelwood model of surface mechanism. The reason for high stability of pendimethalin for UV-degradation even in the presence of catalyst and oxidizing agents were explored. The higher rate of degradation was observed in alkaline medium at pH 11. The degradation process was monitored by spectroscopic techniques such as ultra violet-visible (UV-Vis), infrared (IR) and gas chromatography mass spectroscopy (GC-MS). The major intermediate products identified were: N-propyl-2-nitro-6-amino-3, 4-xylidine, (2, 3-dimethyl-5-nitro-6-hydroxy amine) phenol and N-Propyl-3, 4-dimethyl-2, 6-dinitroaniline by GC-MS analysis and the probable reaction mechanism has been proposed based on these products. 相似文献
10.
The gas-phase photocatalytic oxidation (PCO) of pentane, i-pentane, hexane, i-hexane and heptane over illuminated titanium at ambient temperatures was studied in a continuous stirring-tank reactor and for different values of VOC feed concentrations and relative humidity levels. Conversions achieved were over 90% for residence times from 50 to 85 s and the only products formed were CO 2 and H 2O, while no catalyst deactivation was observed. The obtained results indicate that the molecular and stereochemical structures of the compounds play an important role in the reaction, as the rate was increasing with higher molecular weight, and the presence of a tertiary carbon atom enhanced the reactivity. It was also observed that the increase of the carbon chain by a methyl group had the same influence in the reaction rate in the case of both pentane and i-pentane, while the ratio of the rates for the linear and branched structure was the same for both C 5 and C 6 isomers. The presence of water in the system had an inhibitory effect in all cases. The PCO kinetics was well fit by a Langmuir–Hinshelwood model, modified so as to take into consideration the influence of water vapour. The rate constants ranged from 1.87 × 10 ?7 mol m ?2 s ?1 for pentane to 3.03 × 10 ?7 mol m ?2 s ?1 for heptane, and the VOC adsorption constants from 1.14 10 4 to 2.83 10 4 m 3 mol ?1, while the water adsorption constant was 11.2 m 3 mol ?1. 相似文献
11.
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
12.
Coupled Bi 2O 3/TiO 2 photocatalysts were fabricated by sol–gel and hydrothermal methods and characterized using various spectroscopy techniques. Photocatalytic reduction of Cr(VI) in aqueous solution, together with the synergistic effect of photodegradation of bisphenol A (BPA), was investigated using these coupled Bi 2O 3/TiO 2 under visible-light irradiation. Coupling of Bi 2O 3 inhibited the phase transformation from anatase to rutile and extended absorption region to visible light. Bi ions did not enter TiO 2 lattice and were more likely to bond with oxygen atoms to form Bi 2O 3 on the surface of TiO 2. Photovoltage signals in visible range revealed the effective interfacial charge transfer between Bi 2O 3 and TiO 2. Two percent Bi 2O 3/TiO 2 exhibited the highest photocatalytic activity of visible-light-induced reduction of Cr(VI). The addition of BPA effectively increased the photocatalytic reduction of Cr(VI). Simultaneously, the presence of Cr(VI) promoted the degradation of BPA, which was demonstrated by the investigation of TOC removal yield and generated intermediates. A possible mechanism of photocatalytic reduction of Cr(VI) and degradation of BPA in Bi 2O 3/TiO 2 system was proposed. The synergistic effect, observed between reduction of Cr(VI) and degradation of BPA, provides beneficial method for environmental remediation and purification of the complex wastewater. 相似文献
13.
In agricultural areas, the contamination of feedstuffs with molds and mycotoxins presents major environmental and health concerns. During cattle feeding, fungi and mycotoxins were monitored in corn silage, oilseed cakes and bioaerosols collected in Normandy. Most of the corn silages were found to be contaminated by deoxynivalenol (mean concentration: 1883 μg kg ?1) while a few of oilseed cakes were contaminated by alternariol, fumonisin B 1 or gliotoxin. In ambient bioaerosols, the values for fungi per cubic meter of air varied from 4.3 × 10 2 to 6.2 × 10 5 cfu m ?3. Seasonal variations were observed with some species like Aspergillus fumigatus which significantly decreased between the 2 seasons ( P = 0.0186) while the Penicillium roqueforti group significantly increased during the second season ( P = 0.0156). In the personal bioaerosols, the values for fungi per cubic meter of air varied from 3.3 10 3 to 1.7 10 6 cfu m ?3 and the number of A. fumigatus spores significantly decreased between the 2 seasons ( P = 0.0488). Gliotoxin, an immunosuppressive mycotoxin, was quantified in 3 personal filters at 3.73 μg m ?3, 1.09 μg m ?3 and 2.97 μg m ?3. 相似文献
14.
Introduction TiO 2 anatase nanoplates and hollow microspheres were fabricated by a solvothermal?Chydrothermal method using titanium isopropoxide as a titanium precursor and hydrofluoric acid as a capping agent in order to enhance the formation of the {001} crystal facets of the anatase nanocrystals. Methods These different morphological structures of TiO 2 anatase can be achieved by only changing the solvent, keeping the amount of the precursor and of the capping agent identical during the solvothermal?Chydrothermal process. Results and discussion After calcination of the samples, the adsorbed fluoride atoms on the {001} crystal facets of the TiO 2 anatase nanocrystals were completely removed from their surface according to XPS analysis. The calcined TiO 2 anatase structures were higher crystallized and the specific surface area of the catalysts increased, enhancing their photocatalytic activity in comparison to the non-calcined TiO 2 anatase structures. All TiO 2 anatase samples with adsorbed as well as non-adsorbed fluoride atoms on their {001} crystal facets, exhibited a higher photonic efficiency than Degussa P25, which was used as a reference. Conclusion The fluoride free TiO 2 anatase nanoplates exhibited the best photocatalytic activity in oxidizing the NO gas to NO 2 and NO 3 ?. 相似文献
15.
In this work, the photocatalytic degradation of aqueous microcystin-LR was studied using TiO 2 and ZnO as photocatalysts. The process was optimised and characterised at the bench scale (200 mL); both semiconductors exhibited a high degradation capacity at reaction times of 1 min (degradation greater than 95%). The transient species that were observed indicate that the degradation occurs via the multiple hydroxylation and elimination of the labile peptide residues of the molecule. When photocatalysis was applied in a continuous treatment system (20–50 L), the photocatalytic process exhibited a high degradation efficiency, which resulted in residual microcystin-LR concentrations that were less than 1 μg L ?1 (C 0 = 5 μg L ?1). 相似文献
17.
Background, aim, and scope In literature, the environmental applications of green rust (GR) have mainly been pointed out through the reduction of inorganic
contaminants and the reductive dechlorination of chlorinated organics. However, reactions involving GR for the oxidation and
mineralization of organic pollutants remain very scantly described. In this study, the ability of three synthetic Fe(II)–Fe(III)
green rusts, GR(CO 32−), GR(SO 42−), and GR(Cl −), to promote Fenton-like reaction was examined by employing phenol as a model pollutant. Unlike the traditional Fenton’s
reagent (dissolved Fe(II) + H 2O 2), where the pH values have to be lowered to less than 4, the proposed reaction can effectively oxidize the organic molecules
at neutral pH and could avoid the initial acidification which may be costly and destructive for the in situ remediation of
contaminated groundwater and soils. The green rust reactivity towards the oxidative transformation of phenol was thoroughly
evaluated by performing a large kinetic study, chemical analyses, and spectroscopic investigations. 相似文献
18.
In the present study, bio-apatite/nZVI composite was synthesized through Fe(III) reduction with sodium borohydride and was fully characterized by FTIR, XRD, SEM–EDX, TEM, BET, BJH, and pHPZC. Column experiments were carried out for the removal of phosphate as a function of four operational parameters including initial phosphate concentration (100–200 mg L?1), initial solution pH (2–9), bed height (2–6 cm), and influent flow rate (2.5–7.5 mL min?1) using a response surface methodology (RSM) coupled with Box-Behnken design (BBD). 2D contour and 3D surface plots were employed to analyze the interactive effects of the four operating parameters on the column performance (e.g., uptake capacity and saturation time). According to ANOVA analysis, the influent flow rate and bed height are the most important factor on phosphate uptake capacity and saturation time, respectively. A quadratic polynomial model was excellently fitted to experimental data with a high coefficient of determination (>?0.96). The RSM-BBD model predicted maximum phosphate adsorption capacity of 85.71 mg g?1 with the desirability of 0.995 under the optimal conditions of 135.35 mg L?1, 2, 2 cm, and 7.5 mL min?1 for initial phosphate concentration, initial solution pH, bed height, and influent flow rate, respectively. The XRD analysis demonstrated that the reaction product between bio-apatite/nZVI composite and phosphate anions was Fe3 (PO4)2. 8H2O (vivianite). The suggested adsorbent can be effectively employed up to five fixed-bed adsorption–desorption cycles and was also implemented to adsorb phosphate from real samples. 相似文献
19.
In the present study, an activated charcoal (AC) plate was prepared by physical activation method. Its surface was coated with TiO 2 nanoparticles by electrophoretic deposition (EPD) method. The average crystallite size of TiO 2 nanoparticles was determined approximately 28 nm. The nature of prepared electrode was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area measurement before and after immobilization. The electrosorption and photocatalytic one-stage combined process was investigated in degradation of Lanasol Red 5B (LR5B), and the effect of dye concentration, electrolyte concentration, pH, voltage, and contact time was optimized and modeled using response surface methodology (RSM) approach. The dye concentration of 30 mg L ?1, Na 2SO 4 concentration of 4.38 g L ?1, pH of 4, voltage of 250 mV, and contact time of 120 min were determined as optimum conditions. Decolorization efficiency increased in combined process to 85.65 % at optimum conditions compared to 66.03 % in TiO 2/AC photocatalytic, 20.09 % in TiO 2/AC electrosorption, and 1.91 % in AC photocatalytic processes. 相似文献
20.
During the summertime of 2007/2008, carbon dioxide (CO 2) and methane (CH 4) fluxes across air–water interface were investigated in the littoral zones of Lake Mochou and Lake Tuanjie, east Antarctica, using a static chamber technique. The mean fluxes of CO 2 and CH 4 were ?70.8 mgCO 2 m ?2 h ?1 and 144.6 μgCH 4 m ?2 h ?1, respectively, in the littoral zone of Lake Mochou; The mean fluxes were ?36.9 mgCO 2 m ?2 h ?1 and 109.8 μgCH 4 m ?2 h ?1, respectively, in the littoral zone of Lake Tuanjie. Their fluxes showed large temporal and spatial dynamics. The CO 2 fluxes showed a significantly negative correlation with daily total radiation (DTR) and a weakly negative correlation with air temperature and water temperature, indicating that sunlight intensity controlled the magnitude of CO 2 fluxes from the open lakes. The CH 4 fluxes significantly correlated with local air temperature, water table and total dissolved solids (TDS), indicating that they were the predominant factors influencing CH 4 fluxes. Summertime CO 2 budgets in the littoral zones of Lake Mochou and Lake Tuanjie were estimated to be ?152.9 gCO 2 m ?2 and ?79.7 gCO 2 m ?2, respectively, and net CH 4 emissions were estimated to be 312.3 mgCH 4 m ?2 and 237.2 mgCH 4 m ?2, respectively. Our results show that shallow, open, alga-rich lakes might be strong summertime CO 2 absorbers and small CH 4 emitters during the open water in coastal Antarctica. 相似文献
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