Fluorescence Spectrometer Research Articles

Effect of sputtering temperature on optical properties of TiO2 thin films

TiO2 films with different sputtering temperature were prepared on glass and silicon substrates by magnetron sputtering. The morphology, structure, transmittance and Raman spectra of TiO2 thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and fluorescence spectrometer. The results show that: (1) the size and uniformity of crystalline particles are different at various sputtering temperatures, and with increasing sputtering temperature, the grain size becomes larger and the better uniformity; (2) with the increase of sputtering temperature, the transmittance of the film samples increases in the range of 200 nm-900 nm; (3) the Raman peak of the films is affected not only by the substrate material, but also by the sputtering temperature under the same substrate, the higher the sputtering temperature, the larger the Raman peak.

Heavy metal compartmentalisation in salt marsh and seagrass of the urbanised Swartkops estuary, South Africa

Wetland plants are naturally exposed to high metal concentrations, and often have mechanisms to prevent metal toxicity. This study compared metal concentrations in seagrass (Zostera capensis) and salt marsh (Spartina maritima, Salicornia tegetaria) — to determine their niche as metal sinks. Samples were collected in each season over a year at five sites in the estuary and analysed using a Total X-Ray Fluorescence (TXRF) spectrometer. Spartina maritima and S. tegetaria accumulated in their roots, and displayed little translocation to leaves (BCF = 1–14; TF[leaf/root] < 1). Contrastingly, Z. capensis showed high uptake to its leaves (TF[leaf/root] = 1–8; Mn, Zn, Cr, Pb, Ni, Cu). Spartina maritima and S. tegetaria were identified as good phytostabilisers (BCF > 1, TF[leaf/root] < 1). Compartmentalization was unique to each species, and considering their ecosystem service importance, more plant species should be analysed to estimate their ecological value for management purposes.

Unraveling Arbuscular Mycorrhizal Fungi Interactions in the Exotic Plant Nicotiana glauca Graham for Enhanced Soil Fertility and Alleviation of Metal Pollution

The harm that invasive species cause to the environment has received a lot of attention. It is therefore appropriate that the current research was undertaken to evaluate the effects of invasion by Nicotiana glauca Graham on soil fertility by looking at (i) its contribution to the mycorrhizal potential of the soil, (ii) its impact on soil richness and diversity in terms of the arbuscular mycorrhizal fungi (AMF) community (iii), and its ability to modify the physicochemical characteristics in the invaded soil, specifically cleaning up heavy metal. The current study was conducted at Al Houz plain (Marrakesh region, Morocco), in heavily infested sites by N. glauca. The spores of AMF were isolated using the wet sieving process; the isolated spores were sorted for morphological features using a binocular microscope. The plant roots were thinned and colored before microscopic observation. The most probable number method was used to assess mycorrhizal soil infectivity. Heavy metal contamination in soils was characterized using an X-ray fluorescence spectrometer, and the pollution load index (PLI) was utilized to assess and compare the level of heavy metal contamination at each station. The ability of N. glauca to reproduce was evaluated in order to support one of its invasive characteristics. The estimate indicated that each plant might produce more than three million seeds. This significant number guarantees the plant a great capacity for reproduction and invasion. The extra-significant mycorrhizal potential, which can take the form of spores, mycelium, or vesicles that can regenerate mycorrhizae, was discovered by conducting soil analysis in the rhizospheric soils of N. glauca. This research demonstrated the strong mycotrophic capability of N. glauca and the large mycorrhizal potential of soils. Between 4.85 and 305.5 mycorrhizal propagules were considered to be the most probable number (MPN) per 100 g of dry soil. Based on color, shape and size, AMF were classified into five morphotypes corresponding to five genera. The isolated taxa of AMF with the most diverse spores were Glomus, Rhizophagus, Paraglomus, Scutellospora, and Sclerocystis. The Glomus genus was found to have spores in significant quantity. Furthermore, N. glauca demonstrated a potential involvement in the phytoremediation of damaged soils, with a high pollution load index demonstrating a particularly high accumulation of heavy metals. N. glauca is a highly mycotrophic plant that can boost soil mycorrhizal propagule stock. N. glauca has also been demonstrated to be a phytoremediation plant capable of cleansing contaminated soils. As a result, N. glauca could be considered as a prospective candidate for application in phytoremediation of polluted soils.

Determination of geochemical baseline and pollution of soil heavy metals in Suzhou, China

To investigate the enrichment of soil heavy metals, 50 soil samples were collected and the vanadium (V), chromium (Cr), zinc (Zn), lead (Pb), copper (Cu) and arsenic (As) contents were measured by using an X-ray fluorescence spectrometer. The environmental geochemical baseline values of heavy metals were determined by using standardised methods, and the pollution and enrichment degrees of heavy metals were evaluated based on the geoaccumulation index method and enrichment factor method. The results show that the vanadium, chromium, copper, zinc, lead and arsenic contents vary widely, with mean values of 81.32, 65.54, 17.16, 49.28, 20.04 and 11.68 mg/kg, respectively. Except for arsenic, the average values of the other five elements are lower than the soil background values of Anhui Province. The results of the standard reference method indicate that the six heavy metal elements have a strong correlation with iron (Fe), and the baseline values of heavy metals are 81.33, 65.56, 17.18, 49.29, 20.04 and 11.67 mg/kg, respectively. The mean values of Igeofor the six heavy metals are less than 0, indicating that there is no pollution of heavy metals in the soil of Suzhou. The average enrichment factor is greater than 1, with slight enrichment, and the interference of human activities on soil heavy metals is not obvious.

Spatial Distribution Characteristics and Source Analysis of Heavy Metals in Urban River Surface Sediments from the Lanzhou Reach of the Yellow River

In order to investigate the contamination characteristics and potential sources of heavy metals from the urban river surface sediments in the Yellow River Basin, we selected the Lanzhou reach of the Yellow River as the object of investigation. A total of 46 surface sediment samples were collected along the Lanzhou reach of the Yellow River, and the contents of eight heavy metals, Cr, Ni, Cu, Zn, As, Cd, Hg, and Pb, were determined by using inductively coupled plasma mass spectrometry and an atomic fluorescence spectrometer. Contamination indexes including single factor pollution index (Pi) and geo-accumulation index (Igeo), together with the sediment pollution index (SPI), were used to assess heavy metal pollution characteristics and ecological risk levels in the urban river surface sediments of the Lanzhou reach of the Yellow River. Pearson's correlation analysis (CA), positive matrix factorization (PMF), and principal component analysis/absolute principal component score (PCA/APCS) were jointly employed to quantitatively analyze pollution sources of heavy metals. The results showed that the mean concentrations of the majority of heavy metals exceeded their corresponding background values of Gansu Province and Lanzhou City with the exception of As, and the spatial distribution of high concentrations of heavy metals was mainly concentrated in the corner of the river. Based on the single factor pollution and geo-accumulation indexes of the eight heavy metals, in the Lanzhou reach of the Yellow River, Cr was the dominant pollution element in the urban river surface sediments, followed by Cd and Ni. Additionally, the SPI values for the eight heavy metals in the surface sediments ranged from 0.48 to 8.56, presenting natural to low ecological risk level. Furthermore, source apportionment revealed that a mixture source of industrial and agricultural activities (77.6%) was the largest contributor of Cr, Ni, Zn, As, Cd, and Pb in the urban river surface sediments, followed by natural sources (11.4%) and a mixed source of industrial and traffic activities (11%).

Fluorescence Evolution of Gold Nanoclusters in the Presence of Shapely Silver Nanoparticles and UV-Vis Light

Gold nanoclusters (Au NCs) belong to a class of materials that is highly fluorescent and biocompatible. Bovine serum albumin (BSA) protected gold nanoclusters (BSA-Au NCs) have been extensively used in biological applications due to their easy synthesis and relatively high quantum yield. Therefore, understanding the behavior of BSA-Au NCs in different chemical and physical environments is essential to enhance their application in biological systems. In this study, we investigated the effect of plasmonic nanostructures with different localized surface plasmon resonance (LSPR) wavelengths on the behavior of BSA-Au NCs by recording time-dependent fluorescence spectra in the presence of silver nanoparticles (AgNPs) with various shapes. However, we did not observe any conclusive LSPR-wavelength-dependent fluorescent behavior. Additionally, the fluorescence intensity of BSA-Au NCs exhibited gradual decay under light excitation, even at several hundred μW/cm2 in a fluorescence spectrometer, indicating that they are not as photostable as previously assumed. We found further that the photostability of BSA-Au NCs is affected by the wavelength of the incident light (370, 420, 480, and 550 nm), which can be accurately described using bi-exponential decay functions. Our study provides an easy in situ method to evaluate the photostability of Au NCs under different-wavelength light irradiation using a commercial fluorescence spectrometer.

Role of ZnO/MWCNTs hybrids nanoparticles addition on the tribological behaviour of SN150 paraffinic mineral oil

AbstractNanoparticle incorporation plays an active feature in heat transfer, ultimately enhancing the tribological process under boundary conditions of heat stress. Nanoparticles like zinc oxide (ZnO) and multiwall carbon nanotubes (MWCNT) are well known to significantly affect the cooling and lubrication applications, resulting in improved heat transfer and kinematic viscosity. The present work investigates the tribological performance of ZnO/MWCNTs hybrids as lubricant additive in the paraffinic type of mineral base oil of Group I (SN150) engine oil. The chemical composition of the modified and unmodified oil was examined by an inductively coupled plasma‐optical emission spectrometer (ICP‐OES), energy dispersive x‐ray fluorescence (EDXRF) spectrometer, and Fourier‐transform infrared spectroscopy (FTIR). A ring‐on‐disk tribotester was performed to investigate the tribological behaviour through the linear reciprocating mechanism alloy‐steel contacts. The worn steel alloy surfaces morphology and chemical compositions were examined by scanning electron microscope (SEM), energy‐dispersive x‐ray spectroscopy (EDX), and 3D optical profilometer. Different ZnO/MWCNTs nanomaterial volumetric concentrations were examined in order to determine the most effective performance. According to the tribological results, ZnO/MWCNTs hybrid nanomaterials in the engine oil were found to have significantly higher friction temperature and antiwear capability than the base oil. A volumetric concentration of 3.00 wt% ZnO/MWCNTs nanomaterials to SN150 engine oil imparted excellent wear protection to the steel sample than the pure SN150 base oil. Based on the statistical analysis, the modified oil anti‐wear performance was enhanced by reducing the wear loss by 80.5% and friction temperature by 55.8°C compared with the oil base.

Pedological data for the study of soils developed over a limestone bed in a humid tropical environment.

Lithological characteristics interact with other factors of soil formation to define soil genesis. This becomes more interesting as data on the mineral and elemental oxide components of soils developed from limestone are rarely available in the humid tropical environment. The present study investigated the elemental oxide content, forms of sesquioxides, and clay mineral species in some limestone soils. Soil samples were obtained from three (3) crestal soil profile pits and analyzed for elemental content by the use of an X-ray fluorescence spectrometer, and sesquioxide forms by inductively coupled plasma-mass spectrometer. Analyses were done in triplicates. The mineralogy of the clay fraction was determined on the A, B, and C horizon samples using an X-ray diffraction technique. The occurrence of SiO2 (203-277g/kg), Al2O3 (65-105g/kg), and Fe2O3 (14-95g/kg) in substantial amounts over MnO2, ZrO2, and TiO2 with negligible quantities of CaO suggested comparatively more developed soils in the Agoi Ibami and Mfamosing tropical rainforests. Crystalline form of Fe was dominant over amorphous form, with indications of the co-migration of dithionite Fe with clay to the B horizons of the soils. Quartz, kaolinite, montmorillonite, and chlorite-vermiculite-montmorillonite interlayered minerals dominated the clay mineralogy of the studied soils. Mineral transformation places the soils at the transitory stage from the intermediate to the complete stage of soil development. The expanding clay minerals are most likely to increase plant nutrient adsorption and soil fertility status to accommodate the cultivation of a wider range of crops.

Pilot-scale study and biochemical verification of salt-tolerant catalyst Fe-Bi@γ-Al2O3 for catalytic ozonation of high-salinity wastewater

In this study, Fe-Bi@ γ-Al2O3 was used as a catalyst to construct a heterogeneous catalytic ozonation system for the treatment of high-salinity organic wastewater and its biochemical verification was studied. The optimum operating conditions and degradation mechanism of Fe-Bi@ γ-Al2O3 catalytic ozonation of high salinity wastewater were systematically investigated. The biodegradability of wastewater before and after treatment was also studied. Under the optimum operating conditions of ozone dosage of 160 mg/L, catalyst filling rate of 15%, ratio of height to diameter of 15, hydraulic retention time of 210 min and recycle ratio of 500%, the removal rate of COD is 45.13%. The mechanical strength of Fe-Bi@ γ-Al2O3 catalyst is almost unchanged after being reused for 20 times. The results of Ultraviolet and visible spectrophotometry (UV-Vis), 3D (Three-Dimensional)-fluorescence and Gas Chromatography-Mass Spectrometer (GC-MS)showed that humus, fulvic acid and undissolved microbial organic matter were degraded. In the biochemical verification experiment, after the high salinity wastewater was used to impact the bio-reactor, the mixed liquor suspended solids (MLSS) was basically stable at 9597 mg/L, 8856 mg/L, 9414 mg/L and 8741 mg/L, and the mixed liquor volatile suspended solids (MLVSS) was basically stable at 7042 mg/L, 6940 mg/L, 6949 mg/L and 6519 mg/L. The dissolved oxygen (DO) in the four reactors were 2.9 mg/L, 3.48 mg/L, 3.6 mg/L and 2.92 mg/L respectively, and the sludge Volume Index (SVI30) were 93 mL/g, 98 mL/g, 93 mL/g and 91 mL/g respectively. After two cycles (20d) of 30% high salinity wastewater, the chemical oxygen demand (COD) removal rates of the four reactors were 78%, 84%, 86% and 91%, respectively. When the reaction time is 40 min, the BOD5/COD (B/C) value of the high-salinity wastewater reaches 0.91, and the biodegradability of the wastewater is improved significantly. Scanning electron microscope (SEM) showed that the granular sludge in the reactor had compact structure and smooth surface, and there were a lot of fungi and filamentous microorganisms on the sludge surface.in that condition of salinity stress, the microbial community in the activate sludge changed to a great extent, and Proteobacteria and Bacteroidetes became the main phylum. The Fe-Bi@ γγ-Al2O3 catalyst has good catalytic performance and can be used for deep treatment of high-salt organic wastewater.

Comparison of bismuth atomic lamps for a non-dispersive atomic fluorescence spectrometry

The performance of two types of radiation sources – an electrodeless discharge lamp (EDL) and a boosted discharge hollow cathode lamp (Superlamp) – for atomic fluorescence spectrometry (AFS) was studied and compared using bismuth as a model analyte at 222.8 and 223.1 nm fluorescence lines. Hydride generation was used for analyte introduction to a miniature diffusion flame where the generated bismuthane was atomized. An in-house assembled non-dispersive atomic fluorescence spectrometer was adjusted so that either of the sources could be employed. The optimization of the radiation sources at chosen 40 Hz modulation rate included a duty cycle and applied currents (primary and boost), in addition to proper focusing on the flame atomizer. With optimum operation parameters the sensitivity achieved with the EDL was around an order of magnitude higher than that with the Superlamp, in agreement with the higher radiation intensity measured by an optical power meter and resulting limits of detection of 1.5 pg and 11 pg, for the EDL and the Superlamp, respectively.

Determination of bromine, iodine, and other components in northern Hainan island soil

The emergence of the integrated wavelength-dispersive and energy-dispersive Zetium X-ray fluorescence spectrometer technique offered new chances to analyze elemental distribution with minimal sample preparation in complex matrix geological samples-northern Hainan island soils. Wavelength-dispersive X-ray fluorescence was applied for the measurement of bromine in the northern Hainan island soil. To reduce the fluctuations of the low-bromine-content measurement results, a two-channel measurement of bromine was designed, and the average value of the two-channel measurements was used as the final result. The soil samples in northern Hainan Island were rich in iodine, with a content range of a few µg/g to more than 100 µg/g, and these were particularly suitable to be analyzed by energy-dispersive X-ray fluorescence spectrometer. The geological samples in northern Hainan Island were brown, purple, and brown-red soil containing kaolinite, ilmenite, rutile, anatase, and goethite. These soil samples were rich in titanium, aluminum, and iron. The titanium concentration in the northern Hainan Island soil was anomalously high (up to 15.05%), far exceeding the content range of the calibration curve. Owing to the empirical coefficient matrix correction method, unreliable or even unreasonable results were obtained for some elements. By systematically mitigating matrix effects through the development of custom reference materials and building matrix-matched measurement and calibration routines, the quantification of Vanadium, Barium, and major components in northern Hainan Island soil samples was optimized. The efficacy of the X-ray fluorescence spectrometer method was confirmed by comparison with inductively coupled plasma–optical emission spectroscopy analysis. This work demonstrates the capability of the integrated wavelength-dispersive and energy-dispersive Zetium X-ray fluorescence spectrometer technique for reliable quantitative elemental analysis of complex matrix geological samples.

A cyanostilbene derivative containing –CF3: Synthesis and applications in sensors, information rewritable, encryption and LED

An organic small molecule fluorescent material α-cyanostilbene derivative (2) containing trifluoromethyl (electron acceptor) and dimethylamino (electron donor) has been designed and synthesized by a simple two-step reaction and mild conditions. The structure of target product 2 was characterized using elemental analysis, FT-IR and NMR (1H, 13C, 19F) methods. Compound 2 has strong luminescence in solution and solid states (i.e., dual-state emission, DSE) and aggregation-induced enhanced emission, (AIEE) effect. 2 can be used to recognition the polarity of solvents by “naked eye” under a UV lamp or by fluorescence spectrometer because of its obvious solvatochromic behaviour. 2 can be applied in information rewritable storage, encryption and acid/base sensor, owing to its colour and emission wavelength/intensity can be switched under grinding and acid/base stimulation. The acid/base titration 1H NMR spectra of 2 prove that acidichromism results from the conversion of protonation (2-H+)/deprotonation (2). The results of powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) confirm that the mechanochromic is caused by the morphological transition of 2. Moreover, 2 can be used in light emitting diode (LED) due to its desirable solid-state luminescence performance.

Fate of Copper in Saline–Alkali Soil with Long-Term Application of Biogas Residue

The retention of copper (Cu) in saline–alkali soil (SAS) during long-term application of biogas residue (BR) with a high concentration of Cu raises concerns. In this work, the fate of Cu was detected using adsorption isotherms, scanning electron microscope—energy dispersive spectrometer, Fourier transform infrared spectrometer, X-ray diffraction, isothermal titration calorimetry, X-ray photoelectron spectroscopy, and microzone X-ray fluorescence spectrometer. The results showed that the main groups for Cu adsorption by SAS and BR were carboxyl, hydroxyl, amide and amine. The adsorption of Cu by the carboxyl group was entropy–enthalpy co-driven (|ΔH| &lt; |TΔS|, ΔH &lt; 0). The adsorption of Cu by the amine group was entropy-driven (|ΔH| &gt; |TΔS|, ΔH &gt; 0). The adsorption of Cu on the SAS and BR was achieved by organic matter rather than minerals. The degradation of BR in the SAS increases the content of Cu adsorption groups such as carboxyl and amine groups, and Cu was adsorbed on the surface or inside SAS through organic groups. This study provides further theoretical support for the application of BR in SAS.

Rapid weightless determination of the atomic ratio of iron and platinum in ferrocene derivatives by x-ray fluorescence analysis

When developing new organometallic compounds, the necessity for a rapid control of the elemental composition of the substances obtained arises at different stages of synthesis. This makes urgent the goal of speeding up the procedure of elemental analysis. The XFA method is traditionally used in the laboratory for microanalysis when determining the metal content in the substance composition according to the method of an external standard with a dilution of the substance sample with emulsion polystyrene. Precise weighing of the sample and diluent is required in the manufacture of analyzed reflector samples, since a dilution factor is needed to calculate the content of the elements. When synthetic chemists are interested in the atomic ratio of metals included in the organic matrix rather than in the exact elemental composition of the resulting compound, we propose to eliminate the lengthy weighing procedure and use measured amounts of substances in the manufacture of the analyzed samples. The developed technique is tested on a number of ferrocene derivatives containing platinum atoms, and a rapid weightless method for determining the atomic ratios of Fe and Pt in synthesis products is proposed. Analytical signals were measured on an X-ray fluorescence spectrometer SPECTROSCAN MAX-GVM (NPO Spectron LLC, St. Petersburg) at the wavelengths of FeKα and PtLα lines in the 40 kV/0.5 mA mode. The metal content in the emitter samples was determined by the calibration equations. Simplification of the spectrometry procedure and the absence of weighing significantly speeds up the procedure. The proposed method can be used as a preliminary criterion for success synthesis of the desired product before the complete elemental analysis of the latter.

Application of X-rays to interpret alloying effects on the 3d and 4s4p electron populations of nickel-boron-nitrogen metal matrix composites

For this experiment, nickel-boron and nickel-boron-nitrogen alloys are created using the electrochemical deposition method. Utilizing energy-dispersive X-ray methods, the nickel-boron and nickel-boron-nitrogen alloys are characterized. X-ray diffraction was used to examine the crystal structure of nickel-boron and nickel-boron-nitrogen alloys. An energy dispersed X-ray fluorescence spectrometer is used to gather X-ray photons from the present samples. The number of radiated X-ray photons from the present specimens is used to compute the Kβ/Kα intensity ratios. The theoretical Coulomb and Babushkin gauges are used to calculate the populations of the 3d and 4s4p electrons. The observed data imply that shielding effects from 4s3d orbitals, hybridization, changes in energy levels, and charge transfer mechanism may be the causes of the variance in 3d and 4s4p electron populations. In an effort to clarify the conclusions drawn as a result of all these computations, this study contrasts the results with those of pure nickel.

A Novel Sulfonamide, Molecularly Imprinted, Upconversion Fluorescence Probe Prepared by Pickering Emulsion Polymerization and Its Adsorption and Optical Sensing Performance.

A novel, molecularly imprinted, upconversion fluorescence probe (UCNP@MIFP) for sulfonamide sensing was fabricated by Pickering emulsion polymerization using UCNP@SiO2 particles as the stabilizer and sulfamethazine/sulfamerazine as the co-templates. The synthesis conditions of the UCNP@MIFP were optimized, and the synthesized probe was characterized by scanning electron microscopy, Fourier transform infrared spectrometer, thermogravimetric analyzer, and fluorescence spectrometer. The UCNP@MIFPs showed a good adsorption capacity and a fast kinetic feature for the template. The selectivity experiment revealed that the UCNP@MIFP has a broad-spectrum molecular recognition capability. Good linear relationships were obtained over the concentration range of 1-10 ng/mL for sulfamerazine, sulfamethazine, sulfathiazole, and sulfafurazole, with low limits of detection in the range of 1.37-2.35 ng/mL. The prepared UCNP@MIFP has the potential to detect four sulfonamide residues in food and environmental water.

Separation and online optical characterization of fluorescent components of pyrogenic carbons for carbon dots identification

Optical features of fluorescent components of pyrogenic carbons as flame-formed carbon particulate matter (PM) were studied by setting up a facile and fast method (SEC-Abs/Fluo) based on size exclusion chromatography (SEC) coupled with UV–Visible absorption and fluorescence spectrometers as detectors. The SEC-Abs/Fluo method simultaneously allowed the molecular weight (MW) separation and identification of blue- and green-fluorescent PM components exhibiting size and spectroscopic features typical of carbon dots (CDs). The SEC-Abs/Fluo method allowed the online determination of quantum yield (QY) and optical band gap of fluorescent components also in strongly-scattering carbon suspensions so avoiding tedious pretreatment of carbon samples. From the detailed separation and analysis of blue- and green-fluorescent PM components along with two commercial pitches, aromatic species having MW > 1000 u and band gap <1–1.5 eV resulted to be scarcely or no fluorescent indicating these are the MW and band gap thresholds for fluorescence emission. Indeed, a sharp QY decrease was for the first time noticed in a narrower band gap (1–1.5 eV) range, where carriers can more easily tunnel to defects of the carbon network reducing fluorescence emission. The exponential increase of QY as the band gap rises was found with a more regular trend for the MW-segregated components in comparison to the bulk samples. The method can support and guide the choice of the optimal operating conditions to maximize CD formation and their purification from not-fluorescing components and can also be helpful in disentangling CD fluorescence attribution.

Different Quartz Varieties Characterized by Proximal Sensing and Their Relation to Soil Attributes

Quartz is one of the most common minerals in soils, mostly present in sand and silt fractions. Although quartz is basically formed of SiO2, other elements can be easily detected and assessed nowadays using a portable X-ray fluorescence (pXRF) spectrometer. Our study aims to evaluate the chemical composition of different quartz varieties, identifying their main elements, and relating them to soil attributes. Six quartz varieties (hyaline, amethyst, milky, rose, smoky, and ferriferous) were analyzed via pXRF and 13 oxides/trace elements were identified and used for quartz discrimination (Al2O3, CaO, P2O5, SiO2, Cl, Cr, Fe, K2O, Mn, Rb, S, Ti, and V). Hyaline quartz was characterized by the highest SiO2 and the lowest contents of other elements. Al2O3 was the second-highest compound present in all varieties of quartz, reaching 21,547 mg kg−1 in the smoky variety. S, P2O5, Cl, SiO2, and K2O were the main components determined by Random Forest algorithm for discriminating quartz varieties. Some elements detected may serve as a reserve of nutrients to plants to be released in soils along weathering, depending on quartz particle size, soil texture, leaching, and associated attributes. pXRF enhanced the information on chemical characterization of quartz varieties, without the generation of chemical pollutants.

Effects of Mechanical Stirring and Ultrasound Treatment on the Separation of Graphite Electrode Materials from Copper Foils of Spent LIBs: A Comparative Study

In this paper, mechanical stirring and ultrasonic treatment are used to separate graphite electrode materials from copper foils in recycling spent lithium-ion batteries (LIBs). Firstly, the effects of ultrasonic power (60–180 W), ultrasonic time (1–8 min), stirring speed (420–2000 rpm), and stirring time (1–8 min) on the abscission rate of active material on copper foil were studied. It was found that the peeling-off ratio of electrode material under ultrasonic treatment was 91.34% compared with stirring treatment (84.22%). The removal of electrode material from copper foil during stirring was mainly through mechanical scrubbing. As a comparison, the generation of the microjets induced by ultrasound, the local high-temperature and high-pressure environment, and the free radicals during ultrasonic treatment are the key factors to further improve electrode material removal efficiency. An integrated ultrasound-mechanical stirrer technique can achieve a high-efficient separation performance (approximately 100% peeling-off ratio) of anode electrode materials from copper foils. The effects of mechanical stirring speed, temperature, and treatment time on the peeling-off ratios of the ultrasound-mechanical stirrer-assisted system were investigated. Finally, the results of XRF (X-ray fluorescence spectrometer), XRD (X-ray diffraction), and SEM-EDS (scanning electron microscopy coupled with energy dispersive X-ray spectroscopy) showed that the as-separated graphite electrode material had high purity and contained almost no copper foil impurities. Numerical simulation analyses briefly showed that the difference between pressure and ultrasonic temperature changes in the boundary between different anode layers (graphite on copper foil in aqueous solution) was the main effective factor in the considerable separation of graphite from copper anode foil under ultrasonic-assisted delamination.

Enzyme-free carbon dots@MgO nanocomposite as an efficient sensor for on-site detection and degradation of paraoxon toxins

Serial nanocomposites consisting of blue fluorescent carbon dots (B-CDs) and MgO nanoparticles were facilely prepared. Then on-site detection and degradation of ethyl-paraoxon were achieved and evaluated. It was revealed that ethyl-paraoxon was firstly decomposed into p-nitrophenol by MgO. Then, p-nitrophenol could significantly quench the fluorescence of decorated B-CDs due to an inner filter effect (IFE). The 0.05B-CDs@MgO showed excellent comprehensive performance among the serial xB-CDs@MgO samples due to its relatively high degradation ability towards ethyl-paraoxon and potent initial fluorescence emission intensity at an excitation wavelength of 360 nm between pH 4 and 10. Finally, based on the IFE, on-site paper sensors via color recognition app on a smartphone were explored compared with a conventional fluorescence spectrometer. Both the quantitative fluorescence intensities and G/B values showed the multi-piecewise linear correlations to ethyl-paraoxon concentration up to 3000 μg/mL in river water with a limit of detection to 0.06 μg/mL and 3.48 μg/mL as well as high recovery rates between 99%-102% and 95%–116%, respectively. The in vitro cytotoxicity and phytotoxicity assessment of the 0.05B-CDs@MgO revealed dose-dependent effects. Such portable and integrated fluorescent B-CDs@MgO nanocomposites on paper arrays show excellent potential in shortening the detection time and reducing the detection cost as a new strategy for the on-site quantitative detection and degradation of ethyl-paraoxon in actual river water.