The concept of extracting heat energy from asphalt pavements has been investigated in this study. The scope of work consisted of finite element modeling and testing with small and large scale asphalt pavement samples. Water flowing through copper tubes inserted within asphalt pavements samples were used as heat exchangers in the experiments. The rise in temperature of water as a result of flow through the asphalt pavement was used as the indicator of efficiency of heat capture. The results of small scale testing show that the use of aggregates with high conductivity can significantly enhance the efficiency of heat capture. The efficiency can also be improved by using a reflectivity reducing and absorptivity increasing top layer over the pavement. Tests carried out with large scale slabs show that a larger surface area results in a higher amount of heat capture, and that the depth of heat exchanger is critical. An effective heat exchanger design will be the key in extracting maximum heat from the pavement. 1. BACKGROUND The sun provides a cheap and abundant source of clean and renewable energy. Solar cells have been used to capture this energy and generate electricity. A more useful form of “cell” could be asphalt pavements, which get heated up by solar radiation. The “road” energy solar cell concept takes advantage of a massive acreage of installed parking lots, tarmacs and roadways. The heat retained in the asphalt mixture can continue to produce energy after nightfall—when traditional solar cells do not function. The idea of capturing energy from pavement not only turns areas such as parking lots into an energy source, but also could cool the asphalt pavements, thus reducing the urban heat island effect. The significance of this concept lies in the fact that the massive installed base of parking lots and roadways creates a low cost solar collector an order of magnitude more productive than traditional solar cells. The significantly high surface area can offset the expected lower efficiency (compared to traditional solar cells) by several orders of magnitude, and hence result in significantly lower cost per unit of power produced.
Coordination Structures In article number 2210905, Yi Shen and co-workers present spin-polarized single-atom covalent triazine frameworks for water purification materials. The materials achieve efficient removal of micropollutants in water through a two-step process of adsorption followed by photocatalysis, which restores the vitality of the aqueous environment.
The interfacial physicochemical processes play critical roles in the transport and fate of contaminants in natural environment, yet assessments of these processes are limited by the lack of proper in-situ tools. Recent advances in atomic force microscopy (AFM) techniques lead to new opportunities for in-situ probing these processes, which may provide in-situ information on adsorption kinetics, diffusion pathways, and deposition morphology. In this review, we provided a systematic summary of the progress and achievements in applications of AFM techniques for studying environmental interfacial processes, properties, and molecular interactions, with the primary target of clarifying the fundamental principles that correlate the uniqueness of AFM techniques with the specific and practical demands for environmental studies. Modifying the AFM tips with target compounds allows direct measurements of interfacial properties such as surface hydrophobicity, acid dissociation constant and isoelectric point. Moreover, the interfacial interactions between contaminants and environmental matrixes can be quantified at the molecular level utilizing single-molecule force spectroscopy and atomic-resolution AFM imaging. The environmental interfacial behaviors assessed by AFM-based techniques are essential for revealing the environmental dynamics and risks of contaminants. Finally, the future needs on AFM tips modification and application of AFM in assessing environmental interfacial processes are prospected.
Cathode materials for sodium ion batteries are unstable due to oxidation by electrolyte solution at high voltage. Developing novel solid permeable interfaces as passivation layers is critical to avoid side reactions and increase cycling durability.
The demands for cost-effective solar fuels have triggered extensive research in artificial photosynthesis, yet the efforts in designing high-performance particulate photocatalysts are largely impeded by inefficient charge separation. Because charge separation in a particulate photocatalyst is driven by asymmetric interfacial energetics between its reduction and oxidation sites, enhancing this process demands nanoscale tuning of interfacial energetics on the prerequisite of not impairing the kinetics and selectivity for surface reactions. In this study, we realize this target with a general strategy involving the application of a core/shell type cocatalyst that is demonstrated on various photocatalytic systems. The promising H2O2 generation efficiency validate our perspective on tuning interfacial energetics for enhanced charge separation and photosynthesis performance. Particularly, this strategy is highlighted on a BiVO4 system for overall H2O2 photosynthesis with a solar-to-H2O2 conversion of 0.73%.
This study investigated the sorption kinetics of a model solute (naphthalene) with a series of biochars prepared from a pine wood at 150-700 °C (referred as PW100-PW700) to probe the effect of the degree of carbonization of a biochar. The samples were characterized by the elemental compositions, thermal gravimetric analyses, Fourier transform IR spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller-N(2) surface areas (SA), and pore size distributions. Naphthalene exhibited a fast rate of sorption to PW150 owning a high oxygen content and a small SA, due supposedly to the solute partition into a swollen well-hydrated uncarbonized organic matter of PW150. The partial removal of polar-group contents in PW250/PW350, which increased the compactness of the partition medium, decreased the diffusion of the solute into the partition phase to result in a slow sorption rate. With PW500 and PW700 displaying low oxygen contents and high SA, the solute sorption rates were fast, attributed to the near exhaustion of a partition phase in the sample and to the fast solute adsorption on the carbonized biochar component. The results illustrate that the sorption rate of a solute with biochars is controlled largely by the solute's diffusivity in the biochar's partition phase, in which the medium compactness affects directly the solute diffusivity.
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