共查询到20条相似文献,搜索用时 31 毫秒
1.
2.
《International Journal of Hydrogen Energy》2019,44(43):23856-23867
In this paper, the synergistic effects of advanced oxidization reactions in a combination of TiO2 photocatalysis are comparatively investigated for hydrogen production and wastewater treatment applications. An experimental study is conducted with a photoelectrochemical reactor under a UV-light source. TiO2 is selected as the photocatalyst due to the high corrosion resistant nature and ability to form hydroxyl radicals with the interaction with photons. The synergetic effects of advanced oxidization processes (AOPs) such as Fenton, Fenton-like, photocatalysis (TiO2/UV) and UV photolysis (H2O2/UV) are investigated individually and in a combination of each other. The Fenton type reagent in the reactor is formed by anodic sacrificial of stainless-steel electrode with the presence of H2O2. The influences of various parameters, including pH level, type of the electrode and electrolyte and the UV light, on the performance of the combined system are also investigated experimentally. The highest chemical oxygen demand (COD) removal efficiency is observed as 97.9% for the experimental condition which combines UV/TiO2, UV/H2O2 and photo-electro Fenton type processes. The maximum hydrogen production rate from the photoelectrolysis of wastewater is obtained as 7.0 mg/Wh for the experimental condition which has the highest rate of photo-electro Fenton type processes. The average enhancement with the presence of UV light on hydrogen production rates and COD removal efficiencies are further calculated to be 3% and 20%, respectively. 相似文献
3.
Vítor J.P. Vilar Lívia X. Pinho Ariana M.A. Pintor Rui A.R. Boaventura 《Solar Energy》2011,85(9):1927-1934
Heterogeneous (TiO2/UV, TiO2/H2O2/UV) and homogenous (H2O2/UV, Fe2+/H2O2/UV) solar advanced oxidation processes (AOPs) are proposed for the treatment of recalcitrant textile wastewater at pilot-plant scale with compound parabolic collectors (CPCs). The textile wastewater presents a lilac colour, with a maximum absorbance peak at 516 nm, high pH (pH = 11), moderate organic content (DOC = 382 mg C L−1, COD = 1020 mg O2 L−1) and high conductivity (13.6 mS cm−1), associated with a high concentration of chloride (4.7 g Cl− L−1). The DOC abatement is similar for the H2O2/UV and TiO2/UV processes, corresponding only to 30% and 36% mineralization after 190 kJUV L−1. The addition of H2O2 to TiO2/UV system increased the initial degradation rate more than seven times, leading to 90% mineralization after exposure to 100 kJUV L−1. All the processes using H2O2 contributed to an effective decolourisation, but the most efficient process for decolourisation and mineralization was the solar-photo-Fenton with an optimum catalyst concentration of 100 mg Fe2+ L−1, leading to 98% decolourisation and 89% mineralization after 7.2 and 49.1 kJUV L−1, respectively. According to the Zahn-Wellens test, the energy dose necessary to achieve a biodegradable effluent after the solar-photo-Fenton process with 100 mg Fe2+ L−1 is 12 kJUV L−1. 相似文献
4.
A. Bassam I. Salgado‐Tránsito I. Oller E. Santoyo A.E. Jiménez J.A. Hernandez A. Zapata S. Malato 《国际能源研究杂志》2012,36(14):1314-1324
Artificial neural networks (ANN) were proposed as a multivariate experimental design tool for monitoring a photo‐Fenton treatment of wastewaters containing a synthetic mixture of pesticides. ANN and Nelder‐Mead simplex methods were used to find out the optimum operating parameters of a photo‐Fenton pilot plant. ANN was developed to predict the most important operating parameters (e.g., the total organic carbon and the initial mineralization kinetic rate constants of the reactions), which determine the photo‐catalytic degradation efficiency in photo‐Fenton processes. Experimental measurements of temperature, pH, hydrogen peroxide (H2O2) consumption, initial concentration of Fe2+, and the AE were used as input data for the ANN learning. A feed‐forward with one hidden layer, a Levenberg–Marquardt learning algorithm, a hyperbolic tangent sigmoidal transfer function and a linear transfer function were used to develop the ANN model. The best fitting of the training database was obtained with an ANN architecture constituted by seven neurons in the hidden layer. The simulated results were validated with experimental measurements, showing an acceptable agreement (R2 > 0.99). The ANN was subsequently coupled with a Nelder–Mead simplex method to obtain the optimum operating parameters of the photo‐Fenton pilot plant. The H2O2 consumption was used as key variable for evaluating the optimization procedure. Errors less than 1% between simulated and experimental data were found. The obtained results showed that the use of ANN provides an excellent predictive performance tool with the additional capability to assess the influence of each operating parameter on the removal process of water pollutants. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
5.
利用Fenton法预活化二沉池剩余污泥能够有效改善污泥活性炭的性质,制备性能良好的污泥磁性活性炭.通过考察H_2O_2投加量、H_2O_2/Fe~(2+)投加质量比、活化pH、预活化时间对污泥前驱体和污泥磁性活性炭的影响,探索Fenton法预活化污泥的作用机理.结果表明:Fenton试剂在酸性pH条件下产生羟基自由基,具有强氧化性的·OH破坏污泥胞外聚合物,同时将大分子有机物氧化成中间体和小分子有机物,少量孔隙随着CO_2和H_2O的逸出而形成;Fenton试剂的使用引入了铁,而铁盐是污泥热解的催化剂,能够促进焦油的裂解,加快有机物大分子键的断裂,从而促使更多孔隙的生成. 相似文献
6.
《International Journal of Hydrogen Energy》2019,44(5):2711-2730
The magnetically separable Ag/Fe3O4/RGO nanocomposites (NCs) were synthesized through a green method using Punica Granatum peel extract as a reducing and stabilizing agent. The total phenolic content (TPC) in the Punica Granatum peel extract and the ability of extract to scavenge the DPPH radical were measured and the results proved that the extract has the ability of reduction of Ag+ ions and graphene oxide (GO) to Ag nanoparticles (NPs) and reduced graphene oxide (RGO), respectively. Furthermore, the presence of phenolic compounds in the extract was confirmed using UV–Vis and FT-IR techniques. Deposition of Ag NPs on the surface of Fe3O4/RGO NCs was confirmed by color change from transparent to brown with maximum absorption at 418 nm which is due to surface plasmon resonance of Ag NPs. The crystalline nature of the Ag/Fe3O4/RGO NCs was identified utilizing XRD analysis. The catalytic activity of the green synthesized Ag/Fe3O4/RGO NCs was evaluated in the reduction of organic pollutants such as 4-nitrophenol (4-NP), methylene blue (MB), methyl green (MG) and methyl orange (MO) in water at mild conditions. The results indicated that the biosynthesized NCs have very high and effective catalytic activity for the different types of dyes within few seconds. The morphology and catalytic activity of the Ag/Fe3O4/RGO NCs was compared with Ag/RGO and Ag/Fe3O4 NCs, which were synthesized using Punica Granatum peel extract. The results revealed that the unique synergistic effect of Ag NPs and immobilization over supporters of RGO and Fe3O4 magnetite composite assisted in the reduction of 4-NP, MB, MG and MO. 相似文献
7.
Enhanced heterogeneous ferrioxalate photo-fenton degradation of reactive orange 4 by solar light 总被引:4,自引:0,他引:4
A combined homogeneous and heterogeneous photocatalytic decolourisation and degradation of a chlorotriazine Reactive azo dye Reactive Orange 4 (RO4) have been carried out using ferrous sulphate/ ferrioxalate with H2O2 and TiO2-P25 particles. Solar/ferrous/H2O2/TiO2-P25 and solar/ferrioxalate/H2O2/TiO2-P25 processes are found to be more efficient than the individual photo-Fenton and solar/TiO2-P25 processes. A comparison of these two processes with UV/ferrous/H2O2/TiO2-P25 and UV/ferrioxalate/H2O2/TiO2-P25 reveals that ferrioxalate is more efficient in solar light whereas ferrous ion is more efficient in UV light. The experimental parameters such as pH, initial H2O2, Fe2+, ferrioxalate and TiO2-P25 concentration strongly influenced the dye removal rate in solar processes. The optimum operating conditions of these two combined processes are reported. 相似文献
8.
Landfill leachate treatment by solar-driven AOPs 总被引:1,自引:0,他引:1
Sanitary landfill leachate resulting from the rainwater percolation through the landfill layers and waste material decomposition is a complex mixture of high-strength organic and inorganic compounds which constitutes serious environmental problems. In this study, different heterogeneous (TiO2/UV, TiO2/H2O2/UV) and homogenous (H2O2/UV, Fe2+/H2O2/UV) photocatalytic processes were investigated as an alternative for the treatment of a mature landfill leachate. The addition of H2O2 to TiO2/UV system increased the reduction of the aromatic compounds from 15% to 61%, although mineralization was almost the same. The DOC and aromatic content abatement is similar for the H2O2/UV and TiO2/H2O2/UV processes, although the H2O2 consumption is three times higher in the H2O2/UV system. The low efficiency of TiO2/H2O2/UV system is presumably due to the alkaline leachate solution, for which the H2O2 becomes highly unstable and self-decomposition of H2O2 occurs. The efficiency of the TiO2/H2O2/UV system increased 10 times after a preliminary pH correction to 4. The photo-Fenton process is much more efficient than heterogeneous (TiO2, TiO2/H2O2/UV) or homogeneous (H2O2/UV) photocatalysis, showing an initial reaction rate more than 20 times higher, and leading to almost complete mineralization of the wastewater. However, when compared with TiO2/H2O2/UV with acidification, the photo-Fenton reaction is only two times faster.The optimal initial iron dose for the photo-Fenton treatment of the leachate is 60 mg Fe2+ L−1, which is in agreement with path length of 5 cm in the photoreactor. The kinetic behaviour of the process (60 mg Fe2+ L−1) comprises a slow initial reaction, followed by a first-order kinetics (k = 0.020 , r0 = 12.5 mg ), with H2O2 consumption rate of kH2O2 = 3.0 mmol H2O2, and finally, the third reaction period, characterized by a lower DOC degradation and H2O2 consumption until the end of the experiment, presumably due to the formation of low-molecular-weight carboxylic groups. A total of 306 mM of H2O2 was consumed for achieving 86% mineralization (DOCfinal = 134 mg L−1) and 94% aromatic content reduction after 110 kJUV L−1, using an initial iron concentration of 60 mg Fe2+ L−1. 相似文献
9.
《International Journal of Hydrogen Energy》2022,47(80):33979-33987
Currently, it is a great challenge to improve the stability of Fe-based oxygen reduction reaction (ORR) catalysts in acidic medium, because the Fenton reaction between Fe-based catalyst and H2O2 will reduce the stability of the catalyst. In this study, Fe, Cr and nitrogen-doped carbon (FeCr-N-C) was synthesized via co-impregnation of biomass walnut shells with metal precursor solutions. The FeCr-N-C catalyst has an onset potential of 0.88 V vs. RHE and outperforms the Fe-N-C catalyst in acidic media. Moreover, FeCr-N-C shows negligible activity decay (ΔE1/2 = 14 mV) in 0.1 M HClO4 after 20 000 cycles. The experimental results proved that the bimetal synergism can produce low yield of H2O2 (<2%), which might attribute to variations of local electronic structure. The reactive oxygen species of the catalyst were analyzed by Ultraviolet-visible (UV-Vis) absorption spectra. It was proved that the presence of bimetal inhibited the Fenton reaction between Fe2+/Fe3+ and H2O2, and further improved the stability of the catalysts. Hence, this study proposes an efficient strategy to facilitate the practical application of Fe-based catalysts in acidic media. 相似文献
10.
《International Journal of Hydrogen Energy》2020,45(7):4435-4443
It is extremely necessary to develop highly efficient and low-cost non-noble metal electrocatalysts for hydrogen evolution reaction (HER) under a pH-universal condition in the realm of sustainable energy. Herein, we have successfully prepared phosphorus doped Fe3O4 nanoflowers on three-dimensional porous graphene (denoted as P–Fe3O4@3DG) via a simple hydrothermal and low-temperature phosphating reaction. The P–Fe3O4@3DG hybrid composite not only demonstrates superior performance for HER in 1.0 M KOH with low overpotential (123 mV at 10 mA/cm2), small Tafel slope (65 mV/dec), and outstanding durability exceeding 50 h, but also exhibits satisfying performances under neutral and acidic medium as well. The 3D graphene foam with large porosity, high conductivity, and robust skeleton conduces to more active sites, and faster electron and ion transportation. The phosphorus dopant provides low Gibbs free energy and ability of binging H+. The synergistic effect of 3DG substrate and P–Fe3O4 active material both accelerates the catalytic activity of Fe-based hybrid composite for HER. 相似文献
11.
《Energy》2005,30(11-12):2171-2178
A two-step water splitting process using the ZnFe2O4/Zn/Fe3O4 reaction system was proposed for H2 generation utilizing concentrated solar heat. The mixture of Zn and Fe3O4 was heated to 873 K in flowing steam with an Ar carrier gas, and the H2 gas was generated at 93.4% of the theoretical yield for the reaction of 3Zn+2Fe3O4+4H2O=3ZnFe2O4+4H2 (H2 generation step). The XRD and Mössbauer spectroscopy showed that the Zn‐submitted ferrite (ZnxFe3−xO4; 0.2≤x≤1) (main solid product) and ZnO (minor) were formed in the solid products after the H2 generation reaction. The ZnFe2O4 product, which was formed after the H2 generation step during the two-step water splitting process with the ZnFe2O4/Zn/Fe3O4 system, could be decomposed into Zn (and ZnO) and Fe3O4 by the Xe beam irradiation at 1900 K after 3 min with a 67.8% yield for the reaction of 3ZnFe2O4=3Zn+2Fe3O4+2O2 (O2 releasing step=solar thermal step). 相似文献
12.
Tomoko SugawaraNorimichi Kawashima Takurou N. Murakami 《Journal of power sources》2011,196(5):2615-2620
To predict the durability of polymer electrolyte membranes in fuel cells, the degradation reactions of Nafion 117 films were studied as oxidation reactions with hydroxyl radicals as oxidation accelerators. The radical species were generated by the Fenton reaction between hydrogen peroxide (H2O2) and iron ions (Fe2+). The Nafion degradation kinetics were estimated by fluorine ion (F−) generation. The H2O2 and Nafion degradation reactions fit a pseudo-first-order rate constant. The values of the activation energy and frequency factor are 85 kJ mol−1 and 3.97 × 108 s−1 for H2O2 decomposition in the presence of a Nafion film and 97 kJ mol−1 and 9.88 × 108 s−1 for F− generation. The Nafion surface morphology became rough after reaction for 12 h; small cracks, approximately 100 μm in length, were observed at temperatures below 60 °C. These cracks connected to make larger gaps of approximately 1 mm at temperatures above 70 °C. We also found a linear relationship between H2O2 consumption and F− generation. The rate constant is temperature dependent and expressed as ln(d[F−]/d[decomposed H2O2]) = −19.5 × 103 K−1 + 42.8. F− generated and H2O2 consumed along with the Nafion degradation conditions can be predicted using this relation. 相似文献
13.
《International Journal of Hydrogen Energy》2020,45(30):15041-15046
Fe3+ is a common ion contaminant for the proton exchange membrane water electrolyser (PEMWE). In this work, three-electrode-system was employed to study the effect of Fe3+ on Nafion-bonded IrO2 catalyst which is conventional anode catalyst for PEMWE. Study results showed that Fe3+ contamination decreased IrO2 catalytic activity significantly only when the following two conditions were both satisfied: 1) Nafion resin exists in working electrode; 2) working electrode potential was over 1.471 V (vs. NHE) which is around the initial voltage of oxygen evolution reaction (OER). Besides, the contaminated working electrode activity was recovered to about 16% by being immersed into 3 M H2SO4 solution, but it was recovered to about 59% by ethanol washing method. These study results revealed that Fe3+ plays a role of catalyst for H2O2 production during OER process, which leads to Nafion resin decomposition. The degradation products covered working electrode surface, and thus decreased effective active sites of IrO2. Nafion degradation was further confirmed by analyzing 1) F− content in anode water and 2) FTIR of contaminated Nafion membrane. 相似文献
14.
《International Journal of Hydrogen Energy》2019,44(6):3382-3386
The chemical looping gasification of rice straw using Fe2O3/Al2O3 as oxygen carrier was studied at reaction time of 5–25 min, steam-to-biomass (S/B) ratio of 2.0–4.8, reaction temperature of 750–950 °C, and oxygen carrier-to-biomass of 1.0. The gasification can be regarded completed in 20-min reaction. There exist an optimal S/B ratio of 2.8 and reaction temperature of 900 °C leading to maximum performances yielded are 1.22 Nm3/kg gas yield at 54.6% H2+24.2% CO. The studied Fe2O3 oxygen carrier/rice straw is a feasible platform for syngas production from an agricultural waste. 相似文献
15.
《International Journal of Hydrogen Energy》2023,48(26):9620-9635
Visible-light-induced heterostructure photocatalysts have been regarded as promising candidates in clean energy production and environmental treatment of organic pollutants. In this study, we have prepared nanocomposites of V2O5/N-deficient g-C3N4 (VO/Ndef-CN), which have been characterized by a variety of techniques. The as-synthesized nanocomposites show efficient bifunctional photocatalytic properties toward hydrogen generation and pollutants degradation (dye and antibiotic). The optimized 5VO/Ndef-CN photocatalyst exhibits improved photoactivity for H2 production (5892 μmol g?1 h?1), with a high quantum yield of 6.5%, and fast degradation of organic pollutants, as well as high photocatalytic stability under visible light irradiation. The high photocatalytic efficiency is due to the presence of N defects and S-scheme heterojunction formation, which leads to rapid charge separation, enhanced visible-light absorption, and increased active sites. Furthermore, the possible activity-enhanced mechanism and the photodegradation pathway are proposed based on the experimental and density functional theory (DFT) investigations. 相似文献
16.
Kitiya HongsirikarnXunhua Mo James G. Goodwin Jr. Stephen Creager 《Journal of power sources》2011,196(6):3060-3072
During PEM fuel cell operation, formation of H2O2 and material corrosion occurs, generating trace amounts of metal cations (i.e., Fe2+, Pt2+) and subsequently initiating the deterioration of cell components and, in particular, PFSA membranes (e.g., Nafion). However, most previous studies of this have been performed using conditions not relevant to fuel cell environments, and very few investigations have studied the effect of Nafion decomposition on conductivity, one of the most crucial factors governing PEMFC performance. In this study, a quantitative examination of properties and conductivities of degraded Nafion membranes at conditions relevant to fuel cell environments (30-100%RH and 80 °C) was performed. Nafion membranes were pre-ion-exchanged with small amounts of Fe2+ ions prior to H2O2 exposure. The degradation degree (defined as loss of ion-exchange capacity, weight, and fluoride content), water uptake, and conductivity of H2O2-exposed membranes were found to strongly depend on Fe content and H2O2 treatment time. SEM cross-sections showed that the degradation initially took place in the center of the membrane, while FTIR analysis revealed that Nafion degradation preferentially proceeds at the sulfonic end group and at the ether linkage located in the pendant side chain and that the H-bond of water is weakened after prolonged H2O2 exposure. 相似文献
17.
A. Caravaca V.J. Ferreira A. de Lucas-Consuegra J.L. Figueiredo J.L. Faria J.L. Valverde F. Dorado 《International Journal of Hydrogen Energy》2013
A novel combined single chamber solid electrolyte plus fixed bed reactor configuration was developed for the simultaneous production of H2 and C2 hydrocarbons from a humidified CH4 atmosphere. Hence, a Pt/YSZ/Ag solid electrolyte cell was placed on the top of an active oxidative coupling catalyst powder bed Ce–Na2WO4/SiO2. H2 was produced via steam electrolysis in a Pt cathode of the solid electrolyte cell (H2O + 2e− → H2 + O2−). Simultaneously, the produced O2− ions were electrochemically pumped to the Ag anode, leading to the C2s production, via oxidative coupling of CH4 (4CH4 + 3O2− → C2H4 + C2H6 + 3H2O + 6e−). Additionally, non-reacted O2− molecules desorbed to the gas phase (2O2− → O2+4e−) and reacted with CH4 in the catalyst bed leading to an increase of C2s yield. The influence of different reaction parameters was investigated together with long-term reaction experiments, confirming the stability of this configuration for its practical application. The obtained results demonstrated that the addition of an active catalyst bed strongly enhances both: the efficiency of the single chamber steam electrolysis and the oxidative coupling process. 相似文献
18.
The degradation of 4-chlorophenol (4-CP) contaminated water by Fenton process with or without solar irradiation assistance were investigated. It was found that the COD degradation and mineralization efficiency of 4-CP were more than 90% when a 30 min treatment of solar photo-Fenton oxidation process was applied and under an optimum [H2O2]0/[Fe2+]0 ratio of 40, the COD degradation and mineralization efficiency increased 65% as compared to Fenton oxidation. Meanwhile, the AOS values increased from −0.33 to 2.13 in solar photo-Fenton process while no significant improvement for AOS values was found in Fenton process, implying a higher degree of oxidation for 4-CP in solar photo-Fenton process. In addition, increasing the intensity of solar irradiation seemed to be beneficial for treatment of 4-CP contaminated water. Formation of chloride ion as a result of mineralization of organically bounded chlorine was identified during the treatment of 4-CP solution. Near-stoichiometric accumulation of chlorine was observed during the degradation of 4-CP in both Fenton and solar photo-Fenton processes. However, accumulation rate of chloride ions were much faster in solar photo-Fenton process. The degradation of 4-CP was found to obey a pseudo-first-order reaction kinetics. As compared to Fenton process, the presence of solar light in photo-Fenton process increases the reaction rate by a factor of 6.5 and 15.8 for COD and TOC degradation, respectively. In other words, during the treatment of 4-CP contaminated water, solar photo-Fenton process possesses notably higher mineralization efficiency in a relatively short radiation time as compared to Fenton process, and could enhance the degradation treatment of refractory organic wastewater such as 4-CP in a cost-effective approach. 相似文献
19.
Wang Hui Feng XiaoqiongWang Xiaofang Cheng SanpingGao Shengli 《International Journal of Hydrogen Energy》2008
Pure hydrogen can be stored and supplied directly to polymer electrolyte fuel cell by the redox of iron oxide: Fe3O4 + 4H2 → 3Fe + 4H2O and 4H2O + 3Fe → Fe3O4 + 4H2. Four bimetal-modified samples were prepared by impregnation. The hydrogen storage properties of the samples were investigated. The result shows that the Fe2O3–Mo–Al sample presented the most excellent catalytic activity and cyclic stability. H2 forming temperature and H2 forming rate could be surprisingly decreased and enhanced, respectively. The average H2 forming temperature at the rate of 250 μmol min−1·Fe-g−1 for Fe2O3–Mo–Al in the first 4 cycles could be decreased from 469 °C before the addition of Mo–Al to 273 °C after the addition of Mo–Al. The reason for it may be that the Mo–Al additive in the sample can prevent from the sintering of the particles and accelerate the H2O decomposition due to Mo taking part in the redox reaction. The average storage capacity of Fe2O3–Mo–Al was up to 4.68 wt%. 相似文献
20.
《International Journal of Hydrogen Energy》2020,45(7):4625-4634
Dense ceramic membranes with mixed protonic-electronic conductivity have been widely studied because of their 100% H2 selectivity and directly integrated advantage with high-temperature chemical reactions. In this study, Sr-based dual-phase ceramic membrane SrCe0.95Fe0.05O3-δ-SrFe0.95Ce0.05O3-δ (SCF-SFC) with mixed protonic-electronic conductivity was obtained by automatic phase-separation of SrCe0.5Fe0.5O3-δ (SCF55) precursor. After calcination at 1350 °C, the rationally designed SCF55 precursor auto-decomposed into two thermodynamically stable oxides: Ce-rich phase SrCe0.95Fe0.05O3-δ and Fe-rich phase SrFe0.95Ce0.05O3-δ that functioned as protonic and electronic conductors, respectively. The compositions and microstructures of the auto-formed phases were studied via XRD and SEM analyses. The dual-phase SCF-SFC membrane shows a high hydrogen permeation flux of 0.38 mL min−1 cm−2 at 940 °C. Stability tests indicated that the SCF-SFC membrane exhibited higher and more stable hydrogen permeation flux with less degradation under CO2-containing atmospheres compared with the BaCe0.15Fe0.85O3-δ-BaCe0.85Fe0.15O3-δ (BCF-BFC) membrane. This significant improvement can be attributed to the lower CO2 adsorption and reduced carbonate formation which is indicated by thermogravimetric analysis. 相似文献