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Artificial neural network modeling of a pilot plant jet-mixing UV/hydrogen peroxide wastewater treatment system
摘要： This study deals with the modeling and simulation of an efficient pilot plant photo-chemical wastewater treatment reactor. Treatment of an azo dye (i.e. direct red 23) was performed using a UV/H2O2 process in a jet mixing photo-reactor with 10-L volume. To model the reactor and simulate the treatment process, six important, influential physical and chemical factors such as nozzle angle (hN), nozzle diameter (dN), flow-rate (Q), irradiation time (t), H2O2 initial concentration ([H2O2]0), and pH, were taken into account. In this regard, artificial neural networks (ANNs) were employed as a powerful modeling methodology. Six different ANN architectures were constructed and most appropriate numbers for hidden neuron and learning iteration were determined based on minimization of the mean square error (MSE) function related to the testing data sets. Furthermore, simulation of the reactor efficiency, as well as sensitivity analysis, was performed via the cross-validation outputs. It was found that a three-layered feed-forward ANN composes ten hidden neurons, calibrated at 100th iteration using “trainlm” as learning algorithm and “tansig” and “purelin” as transfer functions in the hidden and output layers can model the process as the best case. The order of importance for variation of the key factors were indicated as [H2O2]0 > t > pH > Q > hN > dN.
关键词： dyes,simulation,wastewater treatment,Advance oxidation process,neural networks,photodegradation,batch reactor
更新于2025-09-23 15:23:52
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Evolution of the infrared emissivity of Ni during thermal oxidation until oxide layer opacity
摘要： The mid-infrared (3–22 μm) emissivity of high-purity Ni has been studied in its pure state, during an isothermal oxidation in air at 730 °C and in the fully oxidized state. Measurements in pure Ni were performed in Ar between 200 and 800 °C and a change of slope in the temperature dependence of the total normal emissivity around its Curie temperature (354 °C) was observed. An oxidation process was carried out at 730 °C for 33 days, when the emissivity stopped evolving and the results were representative of NiO. During the ?rst stages, the emissivity evolved forming the usual interference patterns of semi-transparent ?lms. A mixture of oscillatory and monotonic behaviours of the emissivity as a function of wavelength and oxide layer thickness was found, which manifests as a non-trivial evolution of the total normal emissivity, di?erent than that reported in previous studies. Finally, the emissivity of NiO was measured from below its Néel temperature (252 °C) to 850 °C. It showed the typical shape of a ceramic material with an extra vibrational mode due to two-phonon processes and an additional absorption band around 5 μm in the antiferromagnetic phase produced by magnons. The temperature dependence of its total normal emissivity di?ers signi?cantly from that of a lightly oxidized nickel sample from the literature. Overall, the in?uence of the surface characteristics on the thermal radiative properties of oxidized Ni is thoroughly discussed and highlights the importance of accounting for all possible sources of infrared emissivity evolution in order to make accurate radiative heat transfer calculations.
关键词： Nickel oxide,Infrared emissivity,Radiometry,Radiative heat transfer,Magnetic phase transition,Nickel,Oxidation
更新于2025-09-23 15:23:52
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Structure and photocatalytic oxidation desulfurization performance of CeO2/HTi2NbO7-NS nanocomposite
摘要： CeO2/HTi2NbO7-NS nanocomposite based on HTi2NbO7 nanosheet (HTi2NbO7-NS) and Cerium dioxide nanoparticles (CeO2-NPs) was fabricated through an exfoliation-restructuring method. The as-prepared samples were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), laser Raman Spectroscopy (LRS), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflection spectroscopy (UV-Vis DRS) and N2 adsorption-desorption measurements. The adsorption and photocatalytic properties of the as-prepared samples were evaluated using ethyl mercaptan (EM) in methane gas as the model pollutant. The results indicated that CeO2-NPs were uniformly distributed on the surface of HTi2NbO7-NS and the band gap energy of CeO2/HTi2NbO7-NS nanocomposite was reduced compared with its precursor. The type-Ⅱ heterojunction was formed due to suitable band structures of host and guest materials. The CeO2/HTi2NbO7-NS nanocomposite owns the best adsorption capacity and photocatalytic oxidation activity, which was mainly attributed to the lower band gap and efficient separation of electron-hole pairs of CeO2/HTi2NbO7-NS nanocomposite.
关键词： CeO2/HTi2NbO7-NS,ethyl mercaptan (EM),exfoliation-restructuring,photocatalytic oxidation,type-Ⅱ heterojunction
更新于2025-09-23 15:23:52
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Novel design of photocatalyst coaxial ferromagnetic core and semiconducting shell microwire architecture
摘要： We report a novel design of coaxial core-shell magnetic-semiconductor microwire, as a catalyst under sunlight irradiation. The nano/micro hierarchical architecture-like device is comprised of a coaxial core-shell microwire where the core is the ferromagnetic Fe metal and the shell is formed by a semiconducting hematite layer. The fabrication process of our substrate-free device is simply based on controlled thermal oxidation process revealing a simple and low-cost method. The hematite outer microlayer has a mesoporous structure decorated with nanowires. The ferromagnetic and metallic core assume fundamental importance as to mechanical stability, collect the generated photoelectrons, and to be removed back from the dye solution by a magnetic field gradient or simply a magnet. This nano/micro device has exhibited photocatalytic activity to degrade the methylene blue dye under simulated sunlight irradiation. Additionally, the coaxial magnetic/semiconducting can also be designed as a photoanode to drive water oxidation reaction. The coaxial magnetic/semiconducting photoanode response has shown good chemical stability and long activity under simulated sunlight radiation. In fact, this designed architecture gives novel perspective in the development of substrate free photocatalyst.
关键词： Photoelectrochemical performance,Hematite photoanodes,Photodegradation,Micro/nano architecture,Core-shell microstructures,Thermal oxidation
更新于2025-09-23 15:23:52
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A novel on-line electrochemical transmission infrared spectroscopy to?study the current efficiency of carbonates for?ethanol oxidation reactions in alkaline media
摘要： Research on the reaction mechanism of ethanol oxidation reaction (EOR) is important for the development of highly active EOR electro-catalysts. One of the main difficulties in the EOR study is the quantitative analysis of the non-volatile products. Conventional on-line electrochemical flowing transmission infrared spectroscopy (ETIRS) can only collect a part of the carbonate products of EOR in alkaline media, making the further quantitative study impossible. Herein, a new ETIRS system has been designed and prepared by employing a cation-exchange membrane (Nafion) in the sampling hood. The using of the Nafion membrane can prevent the anions crossing over by confining the generated carbonates in the sampling hood without diffusing into the bulk electrolyte. Therefore, the collection efficiency of the carbonate products as well as the test accuracy of the carbonate current efficiency has been significantly improved. The result of CO stripping reaction shows that ca. 100% of the carbonate product is able to be collected in alkaline media by this new system. The influence of the experimental temperature to the carbonate current efficiency has been further studied on Pt/C toward EOR in alkaline media.
关键词： Transmission infrared spectroscopy,Ethanol oxidation reaction,Platinum,Alkaline media
更新于2025-09-23 15:23:52
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Highly efficient method for oxidation of dissolved hydrogen sulfide in water, utilizing a combination of UVC light and dissolved oxygen
摘要： Hydrogen sul?de is a hazardous contaminant that may appear in well-water and in sewage streams. Here we present a very e?cient way for the removal of H2S from well-water, based on combining UVC light and oxygen. The method was tested with H2S-enriched tap water as well as with natural well water, both of which containing up to 20 mg/L of H2S. A conversion of up to 90% was obtained within a residence time of no more than a few minutes. The quantum e?ciency, de?ned as the ratio between the number of removed H2S molecules to the number of impinging photons, was found to be as high as 70%, depending on conditions. The main product was found to be sulfate, without the appearance of elemental sulfur, i.e. with no major change in turbidity. The absence of sulfur in the outlet stream in of large importance when treating H2S-containing well-water, since it omits the need for posttreatment removal of particles. Results are explained by the excitation of HS- species, following by formation of polysul?de anions that readily react with any formed elemental sulfur, eventually yielding sulfate ions.
关键词： AOP,Water treatment,Sulfate,Hydrogen sul?de,Oxidation
更新于2025-09-23 15:23:52
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Photocatalytic oxidative desulfurization and denitrogenation of fuels over sodium doped graphitic carbon nitride nanosheets under visible light irradiation
摘要： A cost-efficient photocatalytic oxidative denitrogenation and desulfurization system for fuels under visible light was developed on the basis of Na doped g-C3N4 nanosheets catalyst. The process adopted molecular O2 as oxidant to substitute for the expensive H2O2, and it adapted to the removal of small molecules of pyridine and thiophene. Na doped g-C3N4 nanosheets were obtained via a simple mixed-calcination pathway using NaCl as Na source. The structural, photophysical and chemical properties of the photocatalysts were characterized and compared to those of the original g-C3N4. It was verified that Na was successfully doped in the g-C3N4 lattice in a uniform chemical state. Moderate amount of Na doped in g-C3N4 generated the highly dispersed and porous nanosheets, which further improved the surface energy and reduce the recombination rate of electron-hole pairs. Na doped g-C3N4 exhibited enhanced performance simultaneously in the photocatalytic oxidative denitrogenation and desulfurization. The optimal catalyst obtained considerable removal efficiency for pyridine and thiophene, depending on its improved structural and photochemical properties by Na doping. A proposed mechanism revealed that the holes acted as the major active species for the denitrogenation and desulfurization, while the superoxide radicals originating from the combination of electron and O2 gave a promotion effect.
关键词： Pyridine,Sodium doping,Graphitic carbon nitride,Thiophene,Photocatalytic oxidation
更新于2025-09-23 15:23:52
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Antiresonant Oxide Island as a Measure for Improved Single-Mode Emission in VCSELs
摘要： In this paper, we propose a novel ARROW VCSEL structure with an antiresonant oxide island placed inside the resonant cavity with the use of planar oxidation technique. The oxidized island does not only improve single-mode emission, which is one of the most desired effects in vertical-cavity surface-emitting lasers (VCSELs), but also has a strong impact on modal loss associated with each lateral mode and affects the shape of their profiles. In this work, we investigate the physical basis of this impact and show how the dimensions of oxidized island determine optical properties of the ARROW VCSEL, leading to the strongest modal discrimination.
关键词： optical modeling,oxidation,ARROW,VCSEL,antiresonance,waveguiding
更新于2025-09-23 15:23:52
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Effect of photochemical advanced oxidation processes on the formation potential of emerging disinfection by-products in groundwater from part of the Pannonian Basin
摘要： This study evaluates the effect of photochemical advanced oxidation processes (AOPs) (O3/UV, H2O2/UV and O3/H2O2/UV) on the formation potential (FP) of emerging disinfection by-products including nitrogenous by-products (N-DBPs) and haloketones (HKs) in groundwater from part of the Pannonian Basin (AP Vojvodina, Republic of Serbia). Among the N-DBPs, the haloacetonitrile (HAN) precursor contents were 9.83 ± 0.59 μg/L while precursors of halonitromethanes, particularly trichloronitromethane (TCNM) were not detected. Similarly, precursors of HKs as carbonaceous DBPs were also not detected in raw water. Ozonation alone and H2O2/UV process with a lower UV dose maximally decomposed HAN precursors (about 70%) while during O3 based AOPs, HANFP varied significantly. Application of UV photolysis and H2O2/UV processes with increasing UV dose doubled the HANFP. Ozone alone, O3/UV and H2O2/UV slightly increased HKs formation potential, particularly 1,1-Dichloro-2-propanone FP (0.93 ± 0.21 to 2.01 ± 0.37 μg/L). None of the investigated treatments influenced the formation of TCNM precursors. The effect of the applied treatments on bromide incorporation was the most evident for HANs.
关键词： emerging disinfection by-products,ozone,bromide incorporation,photochemical advanced oxidation processes
更新于2025-09-23 15:23:52
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Evaluating the Surface Chemistry of Black Phosphorus during Ambient Degradation
摘要： Black Phosphorus (BP) is emerging as a promising candidate for electronic, optical and energy storage applications, however its poor ambient stability remains a critical challenge. Evaluation of few-layer liquid exfoliated BP during ambient exposure using x-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) allows its surface chemistry to be investigated. Oxidation of liquid exfoliated few-layer BP initially occurs through non-bridging oxide species, which convert to bridging oxide species after ambient exposure. We demonstrate the instability of these bridging oxide species, which undergo hydrolysis to form volatile phosphorus oxides and evaporate from the BP surface. FTIR spectroscopy, scanning transmission electron microscopy and atomic force microscopy were used to confirm the formation of liquid oxides through a continuous oxidation cycle that results in the decomposition of BP. Furthermore, we show that the instability of few-layer BP originates from the formation of bridging oxide species.
关键词： Fourier transform infrared spectroscopy,Black phosphorus,phosphorene,x-ray photoelectron spectroscopy,2D materials,degradation,ambient stability,oxidation
更新于2025-09-23 15:23:52