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Ups and Downs of Water Photodecolorization by Nanocomposite Polymer Nanofibers
摘要： Given the exponentially expanding water pollution causing water scarcity, there is an urgent need for operative nanotechnological systems that can purify water, with insignificant energy consumption, and rapidly. Here, we introduce a nanocomposite system based on TiO2 nanoparticles (NPs) and PES nanofibers (NFs) that can adsorb and then photodecompose organic water pollutants such as dye molecules. We evaluate pros and cons of this system with respect to its purification efficiency and structural properties that can be impacted by the photocatalytic activity of the nanofillers. While the material is superhydrophilic and able to remove 95% methylene blue (MB) from water via adsorption/photodecomposition, its thermomechanical properties decline upon UV irradiation. However, these properties still remain at the level of the neat NFs. The removal behavior is modeled by the first- and second-order kinetic models from the kinetic point of view. The nanocomposite NFs’ removal behavior complies much better with the second-order kinetic model. Overall, such feedbacks implied that the nanocomposite can be effectively applied for water treatment and the structural properties are still as reliable as those of the neat counterpart.
关键词： nanofiber,photodegradation,dye removal,water treatment,photocatalysis
更新于2025-11-14 17:03:37
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The atomic layer etching of molybdenum disulfides using low-power oxygen plasma
摘要： The layered removal mechanisms of molybdenum disul?des (MoS2) using low-power oxygen plasma are investigated in this paper. After the low-power oxygen plasma treatment, the topmost MoS2 layer is completely oxidized. The weaker adhesion of Mo oxides with MoS2 surfaces would lead to the detachment of the topmost oxidized MoS2 layer from the underlying MoS2 ?lms. Since MoS2 is insoluble and Mo oxides are soluble in water, an additional dipping procedure of the sample in de-ionized water will help with the complete detachment of the topmost oxidized MoS2 layer. With a re-sulfurization procedure after the removal process, the partially oxidized MoS2 ?lm remaining on the substrate can be recovered back to a complete MoS2 ?lm. Both optical and electrical characteristics of the MoS2 ?lms can be maintained after the removal procedure. By repeating the same procedure, a layer-by-layer removal of MoS2 is demonstrated, which provides an easy and fast approach to determine the number of layers of the 2D material.
关键词： layered removal,oxygen plasma,layer number controllability
更新于2025-11-14 17:03:37
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Effect of counter-surface chemistry on defect-free material removal of monocrystalline silicon
摘要： To bring light on material removal remains fundamental for promoting the advancement of nanotechnology. In this study, nanoscratching test on silicon surface against Al2O3 microsphere was performed using an atomic force microscope, and the material removal by SiO2 microsphere sliding was taken as a comparison. It was found that nanochannels can be produced on silicon surface by Al2O3 microsphere scratching under much lower contact pressure than the yield limit for plastic deformation, which can be ascribed to water-participated tribochemical reactions. The tribochemical removal was verified by high resolution transmission electron microscope (HRTEM) detection. Further analysis indicates that the tribochemical reactions on silicon surface are strongly affected by the counter-surface chemistry. It is noted that counter-surface chemistry influences the tribochemical reactions via altering the activation energy barrier for forming bonding bridge, and has little influence on decreasing the activation energy barrier for the rupture of Si-Si backbonds in silicon substrate. Compared with SiO2 tip, Al2O3 tip has longer working life span, and the nanochannels fabricated by Al2O3 tip under the same processing conditions exhibit better uniformity even in KOH solution. The results provide useful knowledge for chemical mechanical polishing and tip-based nanomanufacturing processes, and shed new light for enriching the basic theory of nanotribology.
关键词： Tribochemical removal,Nanoscratching,Counter-surface chemistry,Alumina/silicon pair
更新于2025-11-14 17:03:37
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A Review of Conventional and Innovative- Sustainable Methods for Cleaning Reflectors in Concentrating Solar Power Plants
摘要： The severe soiling of re?ectors deployed in arid and semi arid locations decreases their re?ectance and drives down the yield of the concentrating solar power (CSP) plants. To alleviate this issue, various sets of methods are available. The operation and maintenance (O&M) staff should opt for sustainable cleaning methods that are safe and environmentally friendly. To restore high re?ectance, the cleaning vehicles of CSP plants must adapt to the constraints of each technology and to the layout of re?ectors in the solar ?eld. Water based methods are currently the most commonly used in CSP plants but they are not sustainable due to water scarcity and high soiling rates. The recovery and reuse of washing water can compensate for these methods and make them a more reasonable option for mediterranean and desert environments. Dry methods, on the other hand, are gaining more attraction as they are more suitable for desert regions. Some of these methods rely on ultrasonic wave or vibration for detaching the dust bonding from the re?ectors surface, while other methods, known as preventive methods, focus on reducing the soiling by modifying the re?ectors surface and incorporating self cleaning features using special coatings. Since the CSP plants operators aim to achieve the highest pro?t by minimizing the cost of cleaning while maintaining a high re?ectance, optimizing the cleaning parameters and strategies is of great interest. This work presents the conventional water-based methods that are currently used in CSP plants in addition to sustainable alternative methods for dust removal and soiling prevention. Also, the cleaning effectiveness, the environmental impacts and the economic aspects of each technology are discussed.
关键词： CSP re?ectors,dust removal,sustainable cleaning,mirror washing,soiling
更新于2025-09-23 15:23:52
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New automated method for extracting river information using optimized spectral threshold water index
摘要： The accurate extraction of mountain river information is highly significant in water resource investigation and ecological environment protection. However, there are some problems in the existing methods of river information extraction, which are mainly the interference from shadows and buildings. Such interference leads to erroneous and redundant extraction of river information, which leads to inaccuracy or incompleteness. In this study, a precise extraction method of mountain river information is established using Landsat8 image and digital elevation model. The main steps of the river extraction method are as follows: (1) we propose the optimized spectral threshold water index to extract river information; (2) based on digital elevation model data, we simulate the mountain shadows of the study area to remove interference from them; (3) we establish the buffer zone of the river network using digital elevation model data to solve the problem of redundant extraction of river information; (4) we separately calculate and then standardize land surface temperature, albedo, and normalized different building index. The effects of buildings near the river are removed. Results show a relative accuracy of 97.52%. The new method decreases the interference of mountain shadows and buildings.
关键词： Digital elevation model,Mountain shadow,Building removal,River buffer zone,Landsat8
更新于2025-09-23 15:23:52
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The efficiency and mechanism in a novel electro-Fenton process assisted by anodic photocatalysis on advanced treatment of coal gasification wastewater
摘要： A novel dual-chamber photo-electrochemical oxidation system with Fe@Fe2O3/CF cathode was constructed by combining cathodic electro-Fenton and anodic photocatalysis for advanced treatment of biologically pretreated coal gasification wastewater (CGW). In the electro-Fenton cathode chamber, maximal chemical oxygen demand (COD) removal efficiency of 84.2% was arrived within 120 min at current density 10 mA/cm2, initial pH 3 and air flow rate 0.4 L/min for its initial concentration of 200 mg/L. Correspondingly, the effluent concentration of COD, BOD5, TOC and total phenols were 31.5, 3.9, 8.4 and 13.8 mg/L respectively, satisfying the stringent wastewater discharge standard. Moreover, the H2O2 concentration change and wastewater acute toxicity were analyzed. Furthermore, a reasonable degradation mechanism was proposed based on the contribution of hydroxyl radicals (%OH), and thus degradation pathway of phenol as typical pollutant was also speculated. The integrated system is confirmed to be high-effective and stable, and thus it is a potentially promising alternative for treatment toxic refractory industrial wastewater.
关键词： COD removal,Hydroxyl radical,Electro-Fenton,Fe@Fe2O3/CF,Coal gasification wastewater
更新于2025-09-23 15:23:52
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Efficient photocatalytic debromination of 2,2?,4,4?-tetrabromodiphenyl ether by Ag-loaded CdS particles under visible light
摘要： Highly active and visible light-driven Ag-loaded CdS photocatalysts were prepared via a hydrothermal synthesis and photodeposition method. The removal and debromination of 2,2?,4,4?-tetrabromodiphenyl ether was achieved efficiently using this Ag-loaded CdS under visible light, with a removal efficiency of 100% and a debromination ratio of 44.3% being achieved within 30 min. Both the reaction solvent and the water content were found to have a strong influence on the removal efficiency and the debromination ratio. In addition, the stepwise debromination preference was ortho > para, thereby indicating that the main debromination pathway was electron reduction. The stability and efficiency of these Ag-loaded CdS photocatalysts for the removal of BDE47 were satisfactory, and so our results confirmed the development of a promising visible light-driven catalyst for the removal of polybrominated diphenyl ethers.
关键词： Debromination ratio,Visible light-driven,Ag-loaded CdS,Photocatalyst,Removal efficiency
更新于2025-09-23 15:23:52
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Enhanced photocatalytic activity of hydrogenated BiVO4 with rich surface-oxygen-vacancies for remarkable degradation of tetracycline hydrochloride
摘要： In this work, for the first time the hydrogenation treatment was employed to introduce oxygen vacancies on the surface of BiVO4 (BVO) particles, and the influence of hydrogenation on the morphological structure and photocatalytic activity of BVO was explored. Compared to the pristine BVO, a disordered amorphous layer was observed on the surface of the hydrogenated BVO (HBVO) sample. The disordered layer was due to the formation of surface oxygen vacancies in HBVO, as verified by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) spectra. Meanwhile, the band gap of HBVO was slightly narrowed accompanying with a higher optical absorption ability. The photocatalytic measurements demonstrated that under 30 min visible light (λ ≥ 420 nm) illumination the HBVO sample could photocatalytically degrade 98% of tetracycline hydrochloride (TCH), which was much higher than the pristine BVO (~52%), and the calculated pseudo-first-order degradation rate constant (k) of HBVO (~0.118 min?1) was about 5 times that of BVO, confirming that the hydrogenation treatment could significantly improve the photocatalytic activity of BVO. In addition, the photocatalytic mechanism of HBVO for enhanced photocatalytic TCH removal was also discussed. The present work demonstrates the feasibility of employing the hydrogenation treatment to develop highly efficient visible light BVO-based photocatalysts for photocatalytic removal of antibiotics, and also deepens the understanding of the correlation between surface oxygen vacancies and photocatalytic performance of semiconductor photocatalysts.
关键词： BiVO4,Photocatalytic activities,Tetracycline hydrochloride removal,Hydrogenation,Surface oxygen vacancies
更新于2025-09-23 15:23:52
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Environmentally friendly methodology for fouling removal in pipeline based on leaky guided wave generated by quasi-axisymmetric excitation mode
摘要： In this paper, an environmental and innovative clean technique for pipeline fouling is proposed, which is based on leaky ultrasonic guided waves (LUGWs) generated by quasi-axisymmetric excitation mode. The cavitation, which induced by the LUGWs in liquid medium, is employed for removing fouling inside a pipe. Cavitation corrosion and high-speed jet generated by the collapse of cavitation bubbles destroy fouling layer, and no by-products are formed during the removal process, which means that fouling removal in this way is friendly to the environment. The working frequency is determined by finite element method models and experiment. The effect of removal and its uniformity are measured by mass analysis, scanning electron microscope and energy-dispersive spectroscopy from macro to micro. The descaling experiment results show that the proposed method is able to remove the fouling inside a pipe uniformly.
关键词： Finite element method,Fouling removal,Quasi-axisymmetric,Leaky ultrasonic guided waves
更新于2025-09-23 15:23:52
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UV and visible-light driven photocatalytic removal of caffeine using ZnO modified with different noble metals (Pt, Ag and Au)
摘要： In this work, ZnO photocatalyst was modified with different noble metals (Pt, Ag and Au) through photo-deposition method and then characterized by different techniques (XRD, XRF, BET, UV–vis DRS, FESEM, and XPS). The addition of noble metals produces important changes in the light absorption properties with a significant absorbance in the visible region due to the existence of surface plasmon resonance (SPR) observed at about 450 nm and 550 nm for ZnO modified with Ag and Au, respectively. The morphology of the samples was studied by TEM and the size ranges of the different metals were estimated. Noble metal nanoparticles were in every case heterogeneously deposited on the larger ZnO particles. All the prepared photocatalysts were tested in the photocatalytic removal of caffeine (toxic and persistent emerging compound) under UV and visible light irradiation. It was observed an enhancement of photocatalytic caffeine removal from aqueous solutions under UV light irradiation with the increase of metal content (from 0.5 to 1 wt %) for ZnO modified with Ag and Au (Ag/ZnO and Au/ZnO). In particular, Ag/ZnO and Au/ZnO with higher Ag and Au content (1 wt %) allowed to achieve the almost complete caffeine degradation after only 30 min and a TOC removal higher than 90% after 4 h of UV light irradiation. These two photocatalysts were investigated also under visible light irradiation and it was found that their photocatalytic performances were strongly enhanced in presence of visible light compared to unmodified ZnO. In particular, Ag/ZnO photocatalyst was able to reach the complete caffeine degradation and a TOC removal of about 70% after 4 h of visible light irradiation.
关键词： Caffeine removal,Photocatalysis,ZnO,UV and visible light,Noble metals
更新于2025-09-23 15:23:52