- 标题
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Construction of flower-like MoS2/Ag2S/Ag Z-scheme photocatalysts with enhanced visible-light photocatalytic activity for water purification
摘要： Flower-like MoS2/Ag2S/Ag nanocomposites have been elaborately designed and synthesized successfully for the first time. The prepared MoS2/Ag2S/Ag nanocomposites as a novel photocatalysts present effective photocatalytic performance for the photodegradation of congo red (CR), tetracycline hydrochloride (TC-HCl) and disinfection for Pseudomonas aeruginosa (P. aeruginosa). For the photodegradation of TC-HCl, the effect of the pH of the initial solution and photocatalysts dosage was investigated. Furthermore, intermediates of TC-HCl degradation were verified by GC–MS analysis and the possible pathway of the photodegradation was also proposed. The electron paramagnetic resonance (EPR) technique and trapping experiments verified the electron transport path is Z-scheme system (PS-C-PS). Among them, Ag as an electron mediator enhanced the electron transmission rate and accelerated the separation efficiency of photogenerated carriers.
关键词： MoS2/Ag2S/Ag,Photocatalytic,Tetracycline hydrochloride,Water disinfection,Z-scheme
更新于2025-09-23 15:23:52
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Two-dimensional g-C3N4/TiO2 Nanocomposites as Vertical Z-scheme Heterojunction for Improved Photocatalytic Water Disinfection
摘要： Developing highly active photocatalysts towards effective microorganism inactivation is a green and energy-smart strategy in response to the growing demands to water quality under the background of the water crisis. Here, a vertical face-to-face heterojunction was fabricated by horizontally assembling TiO2 nanosheets with {001} facets exposed on graphitic carbon nitride (g-C3N4) sheets through a facile hydrothermal driving coupling. The vertical heterojunction could almost completely disinfect 103 CFU/mL E. coli within 30 min under solar light, which was more efficient than the physically mixed composite and pure g-C3N4 and TiO2. The two-dimensional (2D) morphology provides ample surface area in forming the vertical heterojunction and enables intimate contact which is advantageous to charge transfer between g-C3N4 and TiO2. A Z-scheme charge transportation mechanism is confirmed through band structure analysis and reactive species (RSs) probing and trapping experiments. In comparison with physically mixed composite and the single-phase counterparts, the nanocomposite based on Z-scheme electron transfer mode effectively prompts charge pair dissociation and subsequently encourages bacterial inactivation by boosting the generation of RSs. The constructing vertical Z-scheme heterojunction highlights the potential of 2D nanomaterials for accelerated water sterilization.
关键词： photocatalysis,Z-scheme heterojunction,vertical heterojunction,two-dimensional materials,water disinfection
更新于2025-09-23 15:21:21
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Design and optimization of open-channel water ultraviolet disinfection reactor
摘要： Design and optimization have developed gradually from a methodology for academic attraction into a technology that has made a significant impact on the industrial growth. A careful and well-optimized design of open-channel water ultraviolet (UV) disinfection reactor ensures the achievement of minimum UV dose required, as well as allowing the minimum operational costs. Such UV reactors are mostly utilized in water treatment plants throughout the world to provide the system for disinfecting the drinking water. Yet, at present, lack of rigorous quantitative understanding of behavior in such reactor geometries is shown to limit the versatile and efficient optimization of UV reactor. A new UV reactor design concept is essential that should be able to consider the three significant parameters, namely: uniform UV light propagation within the open-channel UV reactor, providing optimum lamp positioning within the volume of the UV reactor and should allow optimum flow rate of the water. It is approved that computational fluid dynamics (CFD) simulation can be used as a quick and cheap means for design and optimization of water disinfection UV reactor. A novel design and optimization approach which combines CFD modeling, design of experiment (DOE), response surface method (RSM) and goal-driven optimization (GDO) was presented for open-channel water UV disinfection reactor. This methodology includes a heuristic approach from scratch to the final optimal solution. The optimal design variables which have the optimum value of the object functions were identified through proposed methodology. The results showed that the CFD method can be employed for estimation of the optimum design, even though the shape of the open-channel UV reactor is complex. The CFD results reveal that the UV dose distribution and flow of water were largely dependent on the lamp positioning. This paper demonstrates that UV reactor optimization in conceptual design is possible using a commercial CFD package. As a conclusion, the proposed design and optimization technique based on DOE, RSM and GDO could be a suitable technique prior to a final design of open-channel water UV disinfection reactor.
关键词： Water disinfection,Open-channel,Reactor design,Fluence rate,CFD,Optimization
更新于2025-09-19 17:15:36
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Environmental impact analysis applied to solar pasteurization systems
摘要： In many under-developed regions of the world, most people live in rural villages, where the electrical grid is often not available and traditional potabilization systems would be too expensive and technologically too complex to be implemented. Thus every year, millions of people in the world die due to diseases related to water contamination. Solar Pasteurization Systems represents a promising alternative to address such problems, as they can thermally disinfect water employing solar energy alone, without using fossil fuels or electrical grid connection. Evaluating the cradle-to-grave environmental footprint of Solar Pasteurization Systems, and in general of technologies aimed at producing safe drinking water, represents an issue of major importance. This is relevant because an effective solution has to be, at the same time, environmentally and locally sustainable for a given geographical context. In this work, a complete Life Cycle Assessment and Exergo-environmental analysis are performed in order to calculate and compare the eco-profiles of two Solar Pasteurization technologies: a Natural Circulation and a Thermostatic Valve System. Results show that Natural Circulations Systems are generally more environmentally sustainable (0.30 mPt/l) than the Thermostatic Valve System (0.83 mPt/l) thanks to the higher productivity of treated water. A sensitivity analysis is performed to investigate the dependency of the model systems from different operational and environmental conditions, at different installation sites, i.e. Somalia, Brazil and Italy. The main difference is represented by the productivity of the systems. In all cases the solar collector array is the main item responsible for environmental burdens, impacting for almost 45% of the total score. The analysis also shows that the use of solar energy in Pasteurization is important to avoid direct emissions and to lower the global environmental impact connected with thermal energy production compared to the eco-profiles of other widely diffused pasteurization technologies based on the combustion of fossil fuels or biomass that can be used to provide the same function (in general higher than 1.2 mPt/l). Moreover, with the aim of qualitatively assessing the benefit associated with the potential implementation of solar pasteurization systems, an improvement of the sanitary conditions is envisioned, especially in under-developed countries where, definitively, a large scale diffusion would be recommended.
关键词： Solar Pasteurization,Solar Energy,Life Cycle Assessment,Exergo-environmental analysis,Water Disinfection,Water Treatment
更新于2025-09-09 09:28:46