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Epitaxial Graphene Sensors Combined with 3D Printed Microfluidic Chip for Heavy Metals Detection
摘要： Two-dimensional materials may constitute key elements in the development of a sensing platform where extremely high sensitivity is required, since even minimal chemical interaction can generate appreciable changes in the electronic state of the material. In this work, we investigate the sensing performance of epitaxial graphene on Si-face 4H-SiC (EG/SiC) for liquid-phase detection of heavy metals (e.g., Pb). The integration of preparatory steps needed for sample conditioning is included in the sensing platform, exploiting fast prototyping using a 3D printer, which allows direct fabrication of a microfluidic chip incorporating all the features required to connect and execute the Lab-on-chip (LOC) functions. It is demonstrated that interaction of Pb2+ ions in water-based solutions with the EG enhances its conductivity exhibiting a Langmuir correlation between signal and Pb2+ concentration. Several concentrations of Pb2+ solutions ranging from 125 nM to 500 μM were analyzed showing good stability and reproducibility over time.
关键词： heavy metals detection,3D printed flow cell,reusable lab-on-chip,epitaxial graphene,high sensitivity
更新于2025-09-23 15:23:52
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Indirect field technology for detecting areas object of illegal spills harmful to human health: application of drones, photogrammetry and hydrological models
摘要： The accumulation of heavy metals in agricultural soils is a serious environmental problem. The Campania region in southern Italy has higher levels of cancer risk, presumably due to the accumulation of geogenic and anthropogenic soil pollutants, some of which have been incorporated into organic matter. The aim of this study was to introduce and test an innovative, field-applicable methodology to detect heavy metal accumulation using drone-based photogrammetry and micro-rill network modelling, specifically to generate wetlands wetlands prediction indices normally applied at large catchment scales, such as a large geographic basin. The processing of aerial photos taken using a hexacopter equipped with fifth-generation software for photogrammetry allowed the generation of a digital elevation model (DEM) with a resolution as high as 30 mm. Not only this provided a high potential for the study of micro-rill processes, but it was also useful for testing and comparing the capability of the topographic index (TI) and the clima-topographic index (CTI) to predict heavy metal sedimentation points at scales from 0.1 to 10 ha. Our results indicate that the TI and CTI indices can be used to predict points of heavy metal accumulation for small field catchments.
关键词： drones,heavy metals soil pollution,Italy,health,topographic index,photogrammetry
更新于2025-09-23 15:21:21
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Detection of Nutrition and Toxic Elements in Pakistani Pepper Powders Using Laser Induced Breakdown Spectroscopy
摘要： In the current paper, we applied laser induced breakdown spectroscopy (LIBS) to determine the elemental distribution of nutritional and trace heavy metals in pepper powders available in Pakistan using standard calibration curve laser induced breakdown spectroscopy (CC-LIBS) technique. The samples were found to contained elements like K, Ca, Mg, Na, Fe, Zn, Al, Pb, Cu, and Cr. Additionally, we also identified the atmospheric H-alpha line of hydrogen in the spectra which was used to estimate the electron number density. To achieve a highly sensitive LIBS system to determine nutritional and trace amounts of toxic metals in pepper powders and to achieve the best limit of detection, the LIBS system was optimized by studying the dependency of LIBS signal intensity on laser irradiance, variation in spacing between the focusing lens and target as well on the gate width. To justify the results of LIBS study, we also determined the concentration of alike (duplicate) peppers by digesting samples in appropriate solvents using a standard method like inductively coupled plasma-optical emission spectrometry (ICP-OES). The minimum detection limit was recognized for trace heavy metals from calibration curves. The results of LIBS displayed noteworthy conformity with those acquired from the ICP-OES analysis. Results of both the techniques clearly revealed that K was the most abundant element in all the peppers followed by Ca, Mg, Na, Fe, Al, Pb, Zn, Cu, and Cr. The relative accuracy of our LIBS system for different species as compared with ICP technique was in the range of 0.08–0.3 at 2.5 % error confidence. Conclusively, the present work demonstrated the suitability of LIBS technique due to its rapid, non destructive and eco-friendly approach for food security.
关键词： ICP-OES,detection of heavy metals,peppers analysis,laser induced breakdown spectroscopy,plasma parameters,Health impacts of toxic metals,laser applications
更新于2025-09-23 15:21:01
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A general and rapid room-temperature synthesis approach for metal sulphide nanocrystals with tunable properties
摘要： Municipal solid waste incineration fly ash (MSWI FA) and granulated lead smelting slag (GLSS) are toxic industrial wastes. In the present study, granulated lead smelting slag (GLSS) was pretreated as a geopolymer precursor through the high-energy ball milling activation process, which could be used as a geopolymeric solidification/stabilization (S/S) reagent for MSWI FA. The S/S process has been estimated through the physical properties and heavy metals leachability of the S/S matrices. The results show that the compressive strength of the geopolymer matrix reaches 15.32 MPa after curing for 28 days under the best parameters, and the physical properties meet the requirement of MU10 grade fly ash brick. In addition, the toxicity characteristic leaching procedure (TCLP) test results show that arsenic and heavy metals are immobilized effectively in the geopolymer matrix, and their concentrations in the leachate are far below the US EPA TCLP limits. The hydration products of the geopolymer binder are characterized by X-ray diffraction and Fourier transform infrared methods. The results show that the geopolymer gel and Friedel’s salt are the main hydration products. The S/S mechanism of the arsenic and heavy metals in the geopolymer matrix mainly involves physical encapsulation of the geopolymer gel, geopolymer adsorption and ion exchange of Friedel’s salt.
关键词： solidification/stabilization,heavy metals,MSWI fly ash,geopolymer,Friedel’s salt,granulated lead smelting slag
更新于2025-09-19 17:15:36
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Tailoring of graphene quantum dots for toxic heavy metals detection
摘要： The sensitivity of graphene quantum dots towards toxic heavy metals (THMs; Cd, Hg, Pb) can be improved through doping with nitrogen at the vacant site defects. Using density functional theory, we investigate the adsorption of THMs on the graphene quantum dots (GQDs) and nitrogen-coordinated defective GQDs (GQD@1N, GQD@2N, GQD@3N and GQD@4N) surfaces. Thermochemistry calculations reveal that the adsorption of Pb atom on the surfaces is more favorable than Cd and Hg adsorption. The decoration of the vacant defects with nitrogen on the GQD surface substantially increases the charge transfer and adsorption energy values of THMs on the GQD surface (GQD@4N > GQD@3N > GQD@1N > GQD@2N > GQD). The charge transfer and adsorption energy of lead on each of these surfaces are greater than those of cadmium and mercury (Pb > Cd > Hg). Quantum theory of atoms in molecules analysis and non-covalent interaction plots further validate this result while also confirming that Pb atom has a partially covalent and electrostatic nature of interaction at the nitrogen-coordinated vacant site defects. The electron density values—a criterion of bond strength—for the THM...N interactions are greater than for the THM…C interactions, confirming the observed adsorption energy trends of the THMs on the surfaces. The lowering of the HOMO–LUMO energy gap of the surfaces follows the order Pb > Cd > Hg and also results in increased electrical conductivity, which are consistent with the calculated adsorption energy trends. Significant changes in the energy gap and electric conductivity of the surfaces upon THMs adsorption make them promising sensors for metal detection. Finally, time-dependent density functional theory calculations showed that changes such as peak shifts, peak quenching and appearance of new peaks are seen in the UV–visible absorption spectra of the surfaces upon adsorption of THMs, wherein the shifts in peaks correspond to the magnitude of adsorption energy of THMs on the surfaces. These results should motivate the experimentalists towards using rational and systematic modulation of surfaces as sensors for heavy metal detection.
关键词： Adsorption energy,Toxic heavy metals,Charge transfer,UV–visible absorption spectra,Nitrogen doping,Density functional theory,HOMO–LUMO energy gap,Graphene quantum dots
更新于2025-09-16 10:30:52
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Laser-induced breakdown spectroscopy as a promising tool in the elemental bioimaging of plant tissues
摘要： Laser-Induced Breakdown Spectroscopy (LIBS) is an optical analytical technique with a multi-element capability for element bioimaging in plants. During the years of LIBS development, the major application field has been in industry. However, during the last two decades, LIBS became a useful imaging tool in various biologic matrices, e.g. bones, mammals’ organs, and in the plant science. In this work, we present an overview of LIBS achievements in plant bioimaging which started in 2006. The progress in the assessment of spatial element distribution in plants is documented here with respect to the applications in phytotoxicity testing for the following reason: the information on the spatial distribution of elements can reveal a relationship between the exact location of an element and its toxic effect. This review discusses the state of the art of various elements’ bioimaging in plants using LIBS with a spatial resolution at micrometer scale.
关键词： crop plants,macronutrients,laser ablation,nanoparticles,element spatial distribution,micronutrients,2D-mapping,heavy metals,plants,model organisms,phytotoxicity,elemental imaging
更新于2025-09-12 10:27:22
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Removal of heavy metals (Cu2+ and Cd2+) from effluent using gamma irradiation, titanium dioxide nanoparticles and methanol
摘要： Heavy metal pollution has become one of the most serious environmental problems. The aim of this study was to achieve an efficient treatment process of effluents containing 1 mM copper (Cu2+) and cadmium (Cd2+) ions using a combination of gamma irradiation, methanol and TiO2 nanoparticles under different pH values. The results showed that in acidic conditions, removal of Cu2+ and Cd2+ ions by physical adsorption was less than 15% and adsorption of Cd2+ was more than that of Cu2+. In the same condition, the Cu2+ removal percentage by irradiation was greater than that of Cd2+. In basic solutions, due to precipitation of Cd and Cu hydroxides, it was not possible to carry out adsorption experiments on Cd2+ and Cu2+ ions removal by TiO2 and gamma irradiation. Cu2+ and Cd2+ ions removal processes under different conditions could be depicted by the first order kinetics model. The combined application of TiO2 and methanol enhanced Cu2+ and Cd2+ ions removal at all pH levels examined. However, using the combination of TiO2 and methanol at acidic solutions facilitated completely removal of Cu2+ and Cd2+ ions. So that, only using 50 kGy irradiation dose with combination of TiO2 nanoparticles and methanol led to the removal of 99% of coexisting Cu2+ and Cd2+ ions from the acidic wastewater.
关键词： Wastewater,Heavy metals,Nanoparticles,Gamma irradiation,Radiocatalysis,Methanol
更新于2025-09-09 09:28:46
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Ag@Fe <sub/>3</sub> O <sub/>4</sub> Core–Shell Surface-Enhanced Raman Scattering Probe for Trace Arsenate Detection
摘要： Developing an effective and reliable method for trace arsenic (As) detection is a prerequisite for improving the safety of drinking water. In this paper, we designed and prepared Ag@Fe3O4 core–shell nanoparticles (NPs), which were then used as Surface-Enhanced Raman Scattering (SERS) probe for trace arsenate (As(V)) detection. The Ag@Fe3O4 core–shell NPs were prepared by in situ growth of Fe3O4 NPs on the surface of AgNPs, which can effectively combine the strong adsorption ability of Fe3O4 nanoshells to As(V) with high SERS activity of Ag nanocores to decrease the detection limit. By use of Ag@Fe3O4 core–shell NPs for As(V) detection, the detection limit can be as low as 10 (cid:2)g/L, and a good linear relationship between the SERS intensity of As(V) and their concentrations in the range from 10 to 500 (cid:2)g/L was achieved. Furthermore, Ag@Fe3O4 core–shell NPs could be regenerated through desorption of As(V) from Fe3O4 nanoshells in NaOH solution, and then used for recyclic SERS detection. Therefore, it has been demonstrated for the ?rst time that multifunctional Ag@Fe3O4 core–shell SERS probe could be applied to realize the highly sensitive and reversible detection of As(V).
关键词： Drinking Water,Core–Shell,Fe3O4,Heavy Metals,Trace Detection
更新于2025-09-04 15:30:14