Applied Research最新文献

Organic compounds contained in urine, such as urea and creatinine, can compete with pharmaceuticals for the electro-generated oxidants during electrochemical treatment. In addition, urine has a large amount of chloride ions, creating opportunities to produce chlorine and aqueous-free chlorine species via electrolysis. The aim of the present study is to analyze artificial urine as a supporting electrolyte, while studying the removal of the organic components present (urea and creatinine) by employing an experimental design approach. A 2³ factorial design was employed to evaluate the efficiency of the photo-assisted sonoelectrochemical (EC/UV/US) process. Operating conditions were optimized using response surface methodology (MRS), namely: 11.44 mL min⁻¹ flow, 1.940 A at 160 min. The pH was analyzed and a predominance of HOCl (pH < 7.0) can be observed. Response surface methodology was used to investigate the effects and interactions of flow rate, time, and current to track the removal efficiency of organic compounds contained in artificial urine (TOC, creatinine, and urea). Over prolonged electrolysis, the EC/US/UV process achieved removal of TOC (25.7%), creatinine (68.2%), and urea (33.3%), due to the large contribution of highly reactive radical species (^•OH, ^•Cl, ClO⁻).

Time-resolved three-dimensional (3D) X-ray imaging techniques rely on obtaining 3D information for each time point and are crucial for materials-science applications in academia and industry. Standard 3D X-ray imaging techniques like tomography and confocal microscopy access 3D information by scanning the sample with respect to the X-ray source. However, the scanning process limits the temporal resolution when studying dynamics and is not feasible for many materials-science applications, such as cell-wall rupture of metallic foams. Alternatives to obtaining 3D information when scanning is not possible are X-ray stereoscopy and multi-projection imaging, but these approaches suffer from limited volumetric information as they only acquire a very small number of views or projections compared to traditional 3D scanning techniques. Here, we present optimized neural implicit X-ray imaging (ONIX), a deep-learning algorithm capable of retrieving a continuous 3D object representation from only a small and limited set of sparse projections. ONIX is based on an accurate differentiable model of the physics of X-ray propagation. It generalizes across different instances of similar samples to overcome the limited volumetric information provided by limited sparse views. We demonstrate the capabilities of ONIX compared to state-of-the-art tomographic reconstruction algorithms by applying it to simulated and experimental datasets, where a maximum of eight projections are acquired. ONIX, although it does not have access to any volumetric information, outperforms unsupervised reconstruction algorithms, which reconstruct using single instances without generalization over different instances. We anticipate that ONIX will become a crucial tool for the X-ray community by (i) enabling the study of fast dynamics not possible today when implemented together with X-ray multi-projection imaging and (ii) enhancing the volumetric information and capabilities of X-ray stereoscopic imaging.

The interaction of microcroplastics (MP) with dissolved organic matter, especially humic substances, is of great importance in understanding the behavior of microplastics in aquatic ecosystems. Surface modification by humic substances plays an essential role in transport and interaction of MP with abiotic and biotic components. Previous studies on the interaction between MP and humic substances were largely based on a model compound, humic acid (Sigma-Aldrich). In our work, we therefore investigated the interaction of natural organic matter (NOM) sampled from a German surface water with low-density polyethylene particles (LDPE). High-pressure size exclusion chromatography (HPSEC) and UV/vis absorption and fluorescence spectroscopy were used to characterize the incubation solutions after modifications due to the presence of LDPE, and Raman spectroscopy was used to characterize the incubated microplastics. While the studies of the solutions generally showed only very small effects, Raman spectroscopic studies allowed clear evidence of the binding of humic fractions to MP. The comparison of the incubation of NOM and a lignite fulvic acid which also was tested further showed that specific signatures of the humic substances used could be detected by Raman spectroscopy. This provides an elegant opportunity to conduct broader studies on this issue in the future.

The United Nations (UN) has considered water a human right since 1977. However, freshwater available for consumption represents less than 1% of all water on Earth. Groundwater represents one of the largest reserves of drinking water and is susceptible to chemical contamination, especially from pollutants that seep into the soil, such as atrazine, bisphenol A, and tetracycline. These substances, along with Escherichia coli, were selected to simulate contamination in groundwater samples and evaluate the efficiency of electrochemical oxidation using boron-doped diamond anodes and four different anion salts to analyze their impact on the treatment process. After electrolysis, the degradation of tetracycline, bisphenol A and atrazine was found to increase with decreasing current density, with average values of 77%, 96% and 100% at 15 mA cm⁻² and 68%, 83% and 99% at 35 mA cm⁻², respectively. Moreover, the mineralization of these substances showed the same behavior, decreasing from 67%, 64%, and 54% at 15 mA cm⁻² to 52%, 35%, and 49% at 35 mA cm⁻². The analysis of the results showed that the ions present in the solution significantly affect the degradation process and that they interact with the impurities used. For atrazine and tetracycline, the degradation efficiency followed the same pattern, $��\; ��{{\mathrm{PO}}_4}^{�3�\; �-�}��$ < $��\; ��{{\mathrm{SO}}_4}^{�2�\; �-�}��$ < $��\; ��{{\mathrm{NO}}_3}^{}$

A microbial fuel cell (MFC) consisting of a bacterial anode chamber and a microalgal cathode chamber was operated under various conditions to assess its technical feasibility. Maximum achievable power density reached up to 7.13 mW m^–2. The traditional MFC process of conversion of carbon sources to bioelectricity in the anodic chamber was compared with a system circulating anodic effluent to the cathode chamber. The bacteria and microalgae simultaneously carried out the carbon recycling and recovery of energy and resources synergizing the performance of MFC. Results indicated a comparable chemical oxygen demand removal efficiencies at 50% of the retention time compared to the traditional system. The dissolved oxygen concentration varied between 11.95 and 7.44 mg L^–1 with Chlorella vulgaris under alternative light and dark cycles. Despite the variations in electricity output, the system showed its technical feasibility to harness energy for photosynthesis under natural sunlight conditions.

Microplastics (MP) can be detected in all environmental systems. Marine and terrestrial aquatic systems, especially the transported suspended solids, have often been the focus of scientific investigations in the past. Sediments of aquatic river systems, on the other hand, were often ignored due to the time-consuming sample preparation and analysis procedures. Spectroscopic measurement methods counting particle numbers are hardly suitable as detection methods, because there are plenty of natural particles next to a small number of MP particles. Integral methods, such as thermoanalytical methods are determining the particle mass independently of the inorganic components.

In this study, a workflow for sample preparation via density separation and subsequent analysis by thermal extraction desorption-gas chromatography/mass spectrometry is presented, which leads to representative and homogeneous samples and allows fast and robust MP mass content measurements suitable for routine analysis. Polymers were identified and quantified in all samples. Polyethylene and styrene-butadiene rubber are the dominant polymers, besides polypropylene and polystyrene. Overall, total polymer masses between 1.18 and 337.0 µg/g could be determined. Highest MP concentrations in riverbed sediment are found in sites characterized by low flow velocities in harbors and reservoirs, while MP concentrations in sandy/gravelly bed sediments with higher flow velocities are small.

A fast method for microplastic detection is thermal extraction desorption-gas chromatography/mass spectrometry (TED-GC/MS), which uses polymer-specific thermal decomposition products as marker compounds to determine polymer mass contents in environmental samples. So far, matrix impacts of different environmental matrices on TED-GC/MS performance had not yet been assessed systematically. Therefore, three solid freshwater matrices representing different aquatic bodies with varying organic matter contents were spiked with a total of eight polymers. Additionally, for the first time, the two biodegradable polymers polybutylene adipate terephthalate (PBAT) and polylactide (PLA) were analysed using TED-GC/MS. The methodological focus of this work was on detectability, quality of signal formation as well as realisation of quantification procedures and determination of the limit of detection (LOD) values. Overall, TED-GC/MS allowed the unambiguous detection of the environmentally most relevant polymers analysed, even at low mass contents: 0.02 wt% for polystyrene (PS), 0.04 wt% for the tyre component styrene butadiene rubber (SBR) and 0.2 wt% for polypropylene (PP), polyethylene (PE) and PBAT. Further, all obtained LOD values were increased in all matrices compared to the neat polymer without matrix. The LOD of the standard polymers were increased similarly (PS: 0.21–0.34 µg, SBR: 0.27–0.38 µg, PP: 0.32–0.36 µg, PMMA: 0.64–1.30 µg, PET: 0.90–1.37 µg, PE: 3.80–6.99 µg) and their decompositions by radical scission processes were not significantly influenced by the matrices. In contrast, matrix-specific LOD increases of both biodegradable polymers PBAT (LOD: 1.41–7.18 µg) and PLA (0.84–20.46 µg) were observed, probably due to their hetero-functional character and interactions with the matrices. In conclusion, the TED-GC/MS performance is not solely determined by the type of the polymers but also by the composition of the matrix.

An attractive candidate to reduce dependence on fossil fuels and replace them by renewable sources is represented by concentrated solar power (CSP) technology, whose wide deployment is still hindered by its high investment costs. In CSP linear collector plants, a key component with high technological content may be identified in receiver tubes, that are traversed by heat transfer fluid and located on focal line on which solar radiation is concentrated by mirrors. The proposed work aims at developing spectrally selective coatings for receiver tubes able to overcome state-of-the-art technological limitation in terms of both vacuum encapsulation and maximum operative temperature, currently limited at 550°C for molten salts CSP plants. To this aim, a multilayer structure was designed and developed for coating a receiver tube to be employed in open-air environment at temperature of 600°C. The multilayer coating is based on tungsten chromium titanium infrared reflector and includes a solar absorber layer developed with two alternative methods of reactive sputtering and thermal oxidation respectively, finally covered by antireflective and barrier bi-layer of aluminum oxide and silica. Thermal stability was demonstrated of the new developed coatings, since only small variations were measured of the optical parameters after more than 2000 h of aging in open air conditions at temperature of 600°C (on average less than 5%), with final measured solar absorptance α_s of 73% and 87% and thermal emissivity ε_th at 600°C of 18% and 27% for aged multilayer structures including the absorber layer obtained through thermal oxidation and sputtering process, respectively. These results pave the way for further improvement in terms of both optical performance and operative temperature increase, allowing to enhance efficiency and lower costs, thus contributing to ease to deployment of CSP technology.

The stability of polymer composite can be enhanced by altering the structure of the functionalised material with surface modifiers, such as silane coupling agents, organic modifiers, surfactants and others. Surfactant has emerged as a potential modifier since it is eco-friendly and simple. In this study, the surface of functionalised silica (SiO₂) was modified using sodium dodecyl sulphate (SDS) in a polyacrylamide (PAM) composite. Characterisation of the drilling fluid was examined through Fourier-transform infrared spectroscopy, surface tension, contact angle and rheological tests. According to the results, FTIR proved that the modification of PAM was successful. However, all modified PAM showed more hydrophilic properties with low surface tension than bare PAM. The rheological properties of all the modified PAM were varied over all the concentrations of SDS. Meanwhile, the rheological properties of the modified PAM were better than that of bare PAM. Due to the synergistic effect between the surfactant and functionalised material involved, the drilling fluid achieved low plastic viscosity in modified PAM. With a flat gel strength and better rheological properties, 0.2 wt% SDS in modified PAM is a great and promising formula in this study. In the future, further investigation can be conducted on bored pile drilling using this formulation.

Highly fluorescent cesium lead-based (CsPbX₃, X═Br, Cl, I) inorganic metal halide perovskites semiconductors have gained immense popularity in the last decade due to the economic and straightforward fabrication techniques involved in these materials along with their excellent electrical and optoelectronic properties. Cesium lead halide nanocrystals are well known for their fluorescence in the visible region with extremely high internal quantum efficiencies; thus making them highly suitable for the fabrication of efficient light-emitting diodes, transistors and photodetectors. Although perovskite nanocrystals (NCs) are more fluorescent compared to their bulk counterpart, there have been very few reports on the synthesis and characterization of CsPbX₃ perovskite NCs. In this work, we have synthesized and investigated the CsPbBr₃ and CsPbBr₂I NCs to understand the fundamental optoelectronic properties and structural integrity in mixed halide perovskite NCs. We have estimated ~10 nm average particle size of CsPbBr₃ nanocrystals from the high-resolution transmission electron microscopy (HRTEM) while CsPbBr₂I has ~16 nm average particle size with slightly higher polydispersity. Most interestingly, we do not observe any phase segregation of bromide and iodide ions in mixed halide perovskite quantum dots due to finite size effect. This is also confirmed by the energy dispersive X-ray spectroscopy (EDS) mapping data. However, CsPbBr₃ nanocrystals are relatively more stable than the mixed halide perovskite nanocrystals due to fewer defects. Anomalous behavior is observed in the photoluminescence intensity with the variation of precursor concentration indicating a complex nature nanoparticle synthesis.