A method for energy dispersive X-ray fluorescence spectrometric (EDXRF) determination of phosphate ions via the PK & alpha; line in diverse types of water samples is described. The method is based on ultrasonically assisted dispersive micro-solid phase extraction (USA-DMSPE) using lanthanum oxide supported on graphene oxide (La2O3-GO) as a solid adsorbent. Under optimal preconcentration conditions, i.e. sample pH = 5, sample volume 50 mL, adsorbent dose 0.8 mg, sonication time 30 min, a linear response was obtained between the phosphate concentration and the measured analytical signal in the range of 2-300 ng mL-1 with a correlation coefficient of 0.9995. The developed procedure is characterized by good detection and quantification limits of 0.4 and 1.32 ng mL-1. The inter-day and infra-day precision of the method tested at analyte ion concentrations of 5, 50, and 200 ng mL-1 ranges from 1.1 to 4.4% and 1.2-4.7%, respectively. The accuracy of the method was verified by the standard addition method and the inductively coupled plasma atomic emission spectrometry (ICP-OES) comparative technique. The method was implemented for the analysis of various water samples, including artificial seawater. The phosphate content in studied water samples ranges from 23.8 to 121 ng mL-1. Recoveries in samples enriched with phosphates with a known concentration of 94-102%, as well as a relative difference of 1.5-3.8% between results obtained by USA-DMSPE/EDXRF and ICP-OES indicate the usefulness of the method for the quantitative determination of phosphate ions in natural waters. Moreover, the mechanism of chemisorption in the tested system was discussed and the maximum adsorption capacity of La2O3-GO towards phosphate ions (90.1 mg g-1) was determined.

A MnTiO3-TiO2 eutectic composite grown by the micro-pulling down method was studied by Raman spectroscopy. The Raman investigation confirmed that this eutectic consists of the three-dimensional network of TiO2 elongated precipitates interconnected by thin TiO2 lamellas embedded in a MnTiO3 matrix. Raman scattering spectra revealed that the TiO2 phase crystallizes in the rutile structure and the MnTiO3 matrix in the ilmenite structure. The thin lamella regions combine both the TiO2 and MnTiO3 phases. Two Raman lines at 116 cm-1 and 136 cm-1 not observed in a perfect ilmenite single crystal but observed for the eutectic MnTiO3 phase can be used to derive information about deviations in the MnTiO3 structure.

ABS T R A C T The effects of degradation and possible leaching of lithium in the natural conditions were tested by subjecting LiMn2O4 to 3-month degradation in an open air environment. The starting material was characterized structurally using X-ray (XRD) and neutron (NPD) powder diffraction and found to crystallize in the nominal Fd-3m space group. The initial chemical composition was verified using X-ray photoelectron spectroscopy (XPS), electron microscopy (EDS) and neutron prompt gamma activation analysis (PGAA). The effects of degradation were studied by reinvestigating the samples using XRD, XPS and X-ray absorption (XAS). The studies did not find any chemical shift of manganese caused by the removal of Li or any statistically significant degradation of the starting composition suggesting that the spinel cathode material is resistant to possible Li removal due to medium term natural exposure.

Hexavalent chromium is much more toxic than trivalent chromium and is severe environmental pollution caused by human activity. The presence of Cr(VI) ions in waters comes from anthropogenic sources, mainly from industries, and poses an enormous danger. Because of the health effects of Cr(VI) ions on humans, even at very low concentrations, it is necessary to control its levels in the water. However, the determination and speciation of Cr (VI) in water samples remains a sophisticated subject, and according to the WHO recommendation, further studies on reliable and validated methods should be continued. In this study, graphene oxide (GO) was modified with tetraethylenepentamine (TEPA) for the highly effective adsorption and determination of Cr(VI) ions by energy-dispersive X-ray fluorescence (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The experiment shows that Cr(VI) ions can be adsorbed from aqueous solutions at pH 3.5 with a maximum adsorption capacity of 102 mg g-1 using minimal adsorbent doses, 10-50 mu g mL-1, much lower than those of the currently reported adsorbents. These adsorptive properties of GO-TEPA and selectivity toward Cr(VI) in the presence of Cr (III) indicate its potential use as a micro-adsorbent in the determination and speciation of chromium. Due to the high preconcentration factors of 865 and 100, for EDXRF and TXRF, respectively, and high recovery of 98.5-100%, the method based on dispersive micro-solid phase extraction allows obtaining extremely low detection limits of 53 and 3.5 pg mL-1 for EDXRF and TXRF. The exceptional adsorptive properties of GO-TEPA, including the possibility of application in micro-quantities, allow for the development of the ultra-trace method according to the fundamental principles of green analytical chemistry. It significantly expands the possibilities of using the EDXRF, as well as the TXRF technique in water analysis.

At present, most synthetic graphite materials commonly used as anode active ingredients in lithium-ion cells are produced by graphitization of petroleum cokes. The carbon footprint associated with synthetic graphite production is significant. Thus, bio-derived and cheap precursors, such as saccharides, would be an attractive alternative for the sustainable production of graphitic carbons. However, they are non-graphitizing at temperatures as high as 3000 degrees C, preserving the curved, fullerene-like structure of graphene layers and microporosity. Consequently, many lithium ions are consumed during the formation of solid electrolyte interphase films and passivated in the nanovoids. Here, a method for the production of pure, crystalline, graphitic materials based on sucrose disposed of microporosity is presented, which also works with a variety of saccharides and other organic precursors of hard carbons-generally considered incapable of such transformation. This process employs catalytic graphitization by Si particles at high temperatures. The electrochemical response of such derived sucrose-based graphite in Li-ion half-cells demonstrated its feasibility to serve as an anode active material for rechargeable Li-ion batteries. A method for the production of graphitic materials from sucrose is presented, which involves catalytic graphitization by Si particles at high temperatures. The obtained sucrose-based graphite is characterized by high purity, crystallization degree, and density. It demonstrates the potential to act as an anode-active material for Li-ion cells. image

The composite MoO3/MeMoO4 (Me = Cu, Ni, Co, Fe, and Mn) ceramics were obtained by standard hightemperature sintering. Their structure was tested using XRD, SEM, EDS, and XPS. The occurrence of two phases was determined. The main MoO3 phase exhibited an orthorhombic Pnma space group related to the ceramic grain of micrometre size. The second phase was induced by doping with the Me atom. It showed various monoclinic structures and a smaller grain size. The XPS test confirmed the coexistence of the phases, which was reflected in several lines in the patterns. The valence band of the undoped MoO3 was located -3.3 eV below the Fermi level. An additional subband attributed to the Me 3d state was detected within the energy gap. The MoO3/ MeMoO4 composites showed a valence band shifted toward the Fermi level and overlapped with the subband, originating from hybridized Mo 4d - Me 3d states. Magnetic susceptibility showed an antiferromagnetic state below -20 K for the Ni- and Fe-doped composites. The estimated magnetic moment magnitudes indicated the contribution from Me2+ and Me3+ ions that marked the occurrence of oxygen vacancies. Diffuse reflectance spectra exhibited anomalies in the Vis (-500-650 nm) and the NIR (-700-850 nm) ranges and tails in the -900-1000 nm range. The estimated magnitudes of energy gaps were attributed to defect-induced states. They corresponded to deduced oxygen vacancies (2.05-2.38 eV) and states or subbands induced by the introduced Me atoms (1.34-1.89 eV). Electric dc resistivity temperature dependence showed thermally activated dependence. The estimated activation energy varied from 0.27 eV to 0.58 eV, depending on the doping of the Me atom. The electric features were consistent with the electronic structure determined using XRD and XPS tests.

Hexavalent chromium is much more toxic than trivalent chromium and is severe environmental pollution caused by human activity. In this paper, graphene oxide (GO) was modified with tetraethylenepentamine (TEPA) for the highly effective adsorption of Cr(VI) ions. Adsorption isotherms and kinetic studies indicated that the adsorption of Cr(VI) ions occurs in a monolayer coverage. X-ray photoelectron spectroscopy reveals the presence of Cr(III) species in the solid phase after adsorption of Cr(VI) ions, which is usually explained by the adsorption-reduction mechanism. However, the adsorption and subsequent elution experiment revealed the presence of only Cr(VI) and ruled out such a mechanism. This issue is discussed in the paper. The experiment shows that Cr(VI) ions can be removed from aqueous solutions at pH 3.5 with a maximum adsorption capacity of 102 mg g-1 using minimal adsorbent doses, 10-50 mg L-1, much lower than those of the currently reported sorbents. These adsorptive properties of GO-TEPA indicate its potential use in removing Cr(VI) from water and in analytical chemistry as a micro-adsorbent. This paper shows that ultra-trace Cr(VI) ions can be accurately determined in complex matrix samples by total-reflection X-ray fluorescence spectrometry with an extremely low detection limit of 3.5 pg mL-1.

ss-cyclodextrin/graphene oxide (GO-ss-CD) was applied for dispersive micro-solid phase extraction (DMSPE) of uranyl ions (UO22+) from water samples and their determination by energy-dispersive (EDXRF) and totalreflection X-ray fluorescence spectrometry (TXRF). The structure of GO-ss-CD was characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy. The results of batch adsorption experiment indicate that the maximum recoveries for UO22+ ions are observed at pH 4.5. The Langmuir isotherm model fits the adsorption data, which stands for the chemisorption mechanism. The obtained adsorption capacity of 87.7 mg g(-1) indicates a great potential of the synthesized adsorbent in the UO22+ ions preconcentration. The GO-ss-CD exhibits high resistance to high ionic strength (up to 2 mol L-1), indicating that high salinity samples can be treated with the evaluated preconcentration procedure. The obtained limit of detection values were 0.40 mu g L-1 for the EDXRF and only 0.014 mu g L-1 for TXRF analysis. The accuracy of the method was verified by analyzing certified reference material (spring water NIST-SRM 1640a) and spiked water samples (mineral, lake, river, and artificial sea water).

The dielectric properties of Ag1-xLixNbO3 (ALNx) ceramics (x <= 0.08) were investigated in a broad frequency range (20 Hz - 90 THz). Nature of the room temperature phase of ALNx (x <= 0.04) ceramics is ferrielectric while for x >= 0.05 ferroelectric. The frequency dependence of dielectric permittivity is mainly caused by the relaxational mode close to the ferrielectric/ferroelectric phase transition temperature and domains dynamics at lower temperatures. At room temperature and 10 GHz frequency the dielectric permittivity is quite high (270 for ALN0), while dielectric losses tan delta low (0.037 for ALN0) for all ALN compositions, therefore these ceramics are attractive for various microwave applications. Moreover, their piezoelectric properties were also investigated and the highest piezoelectric coefficient value was observed for ALN6 (200 pC/N at room temperature and 750 pC/N at 465 K). For ALNx ceramics when x >= 0.06 15 polar modes were distinguished in the IR spectra and 20 polar modes for ALNx ceramics with x < 0.06, however the number or modes is temperature independent in investigated temperatures range (103-500 K). (c) 2022 Elsevier B.V. All rights reserved.

In a public space there are several reports of materials with general stoichiometry CaCoSinO2n+2. Pyroxene CaCoSi2O6 is probably the best-known representative for n = 2 but not much is known about materials with n = 3 and n = 4. In this study, attempts were carried out to synthesize those phantom materials and it was found that they do not exist as a single phase. A quantitative XRD analysis revealed that their chemical composition is correct but the formula should be written as CaCoSi2O6 + (n-2)SiO2. Similar qualitative conclusions were drawn from investigation of magnetic (DC magnetometry) and electronic properties using X-ray Photoelectron Spectroscopy (XPS) and Si K edge X-ray Absorption Spectroscopy (XAS). Additionally, the DFT ab initio calculations were carried out to obtain electronic signature from band structure of CaCoSi2O6. The apparent influence of the excess of SiO2 on magnetic properties of this "series" can be understood in terms of presence and suppression of secondary phases like Ca2CoSi2O7, which form when the starting materials are not homogenized properly. Addition of surplus SiO2 suppresses their formation leaving clear signature from CaCoSi2O6, which also can be synthesized from stoichiometric mixture using proper techniques.

The 5-aminolevulinic acid (5-ALA) prodrug is widely used in clinical applications, primarily for skin cancer treatments and to visualize brain tumors in neurosurgery. Unfortunately, its applications are limited by unfavorable pharmacological properties, especially low lipophilicity; therefore, efficient nanovehicles are needed. For this purpose, we synthesized and characterized two novel water-soluble fullerene nanomaterials containing 5-ALA and d-glucuronic acid components. Their physicochemical properties were investigated using NMR, XPS, ESI mass spectrometry, as well as TEM and SEM techniques. In addition, HPLC and fluorescence measurements were performed to evaluate the biological activity of the fullerene nanomaterials in 5-ALA delivery and photodynamic therapy (PDT); additional detection of selected mRNA targets was carried out using the qRT-PCR methodology. The cellular response to the [60]fullerene conjugates resulted in increased levels of ABCG2 and PEPT-1 genes, as determined by qRT-PCR analysis. Therefore, we designed a combination PDT approach based on two fullerene materials, C60-ALA and C60-ALA-GA, along with the ABCG2 inhibitor Ko143.

In this work, the superior nanoadsorbent (GO-TSC) for highly effective adsorption of mercury ions from water solutions was developed, by grafting the thiosemicarbazide molecules (TSC) to the graphene oxide (GO) nanosheets. GO-TSC combines the extraordinary properties of GO, such as high specific surface area and an excellent dispersibility in aqueous solutions with strong affinity of TSC molecules to Hg(II) ions. The experiments show that the adsorption of Hg(II) on the GO-TSC is significant in a broad pH range, and reaches maximum value (close to 100%) at pH 3-4, with the maximum adsorption capacity of 231 mg g(-1) at pH 3.5. Due to the excellent dispersibility of GO-TSC nanosheets, an extremely small GO-TSC dosage of 5 mg L-1 is required to remove Hg(II) ions from aqueous solution in a short contact time (from 10 to 30 min for adsorption of 90-95% Hg(II)). X-ray photoelectron spectroscopy indicate that the adsorption of Hg(II) is based on the chemisorption, and Hg(II) ions can be complexed by a single TSC molecule as bidentate chelating agent (S-Hg-N), or two neighboring TSC molecules (S-Hg-S). Due to the formation of strong S-Hg-N and S-Hg-S interactions, the selectivity of the GO-TSC toward Hg(II) is impressive. Hg(II) ions can be removed from aqueous solutions with very high ionic strength and high concentration of potentially coexisting ions.

Correction for ‘Nano-bismuth sulfide based dispersive micro-solid phase extraction combined with energy dispersive X-ray fluorescence spectrometry for determination of mercury ions in waters’ by Katarzyna Pytlakowska et al., J. Anal. At. Spectrom., 2021, 36, 786–795, DOI: 10.1039/D0JA00477D.

This paper refers to the structural and magnetic properties of [(Fe80Nb6B14)0.88Dy0.12]1−xZrx (x = 0; 0.01; 0.02; 0.05; 0.1; 0.2; 0.3; 0.5) alloys obtained by the vacuum mold suction casting method. The analysis of the phase contribution indicated a change in the compositions of the alloys. For x < 0.05, occurrence of the dominant Dy2Fe14B phase was observed, while a further increase in the Zr content led to the increasing contribution of the Fe–Zr compounds and, simultaneously, separation of crystalline Dy. The dilution of (Fe80Nb6B14)0.88Dy0.12 in Zr strongly influenced the magnetization processes of the examined alloys. Generally, with the increasing x parameter, we observed a decrease in coercivity; however, the unexpected increase in magnetic saturation and remanence for x = 0.2 and x = 0.3 was shown and discussed.

The results of a PM4 (airborne particles with an aerodynamic diameter less than 4 µm) study in Katowice and in the surrounding area in homes with and without environmental tobacco smoke (ETS) are presented. It was found that the average concentration of PM4 inside the homes with ETS was between 126 µg m−3 (in Jaworzno) and 208 µg m−3 (in Katowice)—significantly higher than in the homes without smokers (55–65 µg m−3). The mean of the indoor to outdoor ratios (I/O) for PM4 varied greatly, ranging from 0.6 in the apartments without smokers in Katowice to 5.2 in the homes with smokers in Jaworzno. The highly polluted by ETS indoor air causes children aged 14–15 living in these homes to inhale from 2.5 to 6.6 mg of PM4 more per day than their peers living in non-ETS homes. X-ray photoelectron spectroscopy (XPS) was used to determine the surface chemical composition of the studied indoor airborne particles. Carbon, including elemental carbon, and oxygen-containing species dominated the particulate surface, with traces of Si, N, S, Na, Al, Zn, and K present. The surface layer of PM4 from the homes with ETS contains significantly more carbon and less oxygen than the airborne particles collected in the homes without smokers, which can be explained by the high emission of carbon during tobacco smoking.

A fast and low-cost method for the highly selective determination of ultra-trace Hg(ii) ions at ppt level using total-reflection X-ray fluorescence spectrometry.

According to the developed bioinspired method in the one-step procedure, the material with the petal effect was switched to lotus one. Therefore, highly hydrophobic and super-hydrophobic materials with tunable adhesive properties and fractal-like structures were successfully produced with high efficiency (67-84%). The work's essence was to modify chemically selected powders of lanthanide oxides (CeO2, Pr6O11, Nd2O3, and Gd2O3). High effectiveness of the functionalization process with 1H,1H,2H,2H-perfluorooctyltriethoxysilane (FC6) and n-octyltriethoxysilane (C6) was proven by various techniques, e.g. XPS, HR-TEM, ATR, XRD, zeta potential. Materials with water contact angle between 143.6 degrees (CeO2-C6) and 175.5 degrees (Nd2O3-FC6) with thermally stable nanolayer (up to 380 degrees C) were generated. Surfaces functionalized with FC6 possessed a polar component of surface free energy (SFE) close to zero. Water behavior in contact with the modified materials was studied, taking into consideration the unique electron structure of lanthanides assessed by goniometric measurement, also adhesion and spreading pressure were determined. Very low adhesion and polar SFE partly resulted in immediate bouncing of water droplet upon contact with the modified surface. The presented method allows preparing stable materials with a high potential in materials chemistry and modulation of surface features and engineering (e.g. heat transfer fluids, specific coating).

In this paper, the determination of ultratrace heavy metal ions was developed by combining a preconcentration method using graphene oxide/carbon nanotubes membranes (GO/CNTs) and total-reflection X-ray fluorescence spectrometry (TXRF). Due to the excellent adsorptive properties of the GO, the foregoing membranes are suitable for effective simultaneous sorption of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) from aqueous solutions. In this method, the aqueous solution is passed through the GO/CNTs membrane. The analytes are eluted from the GO and afterward transferred onto a siliconized quartz reflector for further TXRF analysis using W and Mo target X-ray tubes. The maximum recoveries for all the elements were obtained at pH 5; thus it was chosen for all further experiments. The face centered central composite design was performed to study the influence of the flow-rate and volume of the solution on the recovery of the determined metal ions. Recovery values higher than 96% for all studied metals allow performing efficient preconcentration with an enrichment factor of 133, achieving the limits of detection (LODs) in the range of 0.08-0.21 ng mL(-1) for W target X-ray tube with a measurement time of 2000 s, and much lower LODs for Mo target X-ray tube: 0.001-0.002 ng mL(-1) with the exception for Cd (0.11 ng mL(-1)) with a very short measurement time of 600 s. Certified reference materials of spring water and seawater were examined to verify the reliability of the method. The evaluated procedure does not require toxic reagents or organic solvents, thus minimizes the portion of the sample for TXRF measurement, and stands in good accordance with green analytical chemistry basic principles.

In this paper, the graphene oxide (GO) decorated with fullerenol nanoparticles C-60(OH)(22) has been designed for the highly selective separation and ultrasensitive determination of lead ions. The grafting fullerenol nanoparticles to the surface of GO solves the problem of their high solubility in aqueous solutions and simultaneously uses their high hydrophilicity and deprotonation ability. The research has revealed unique adsorption properties of GO-C-60(OH)(22) toward Pb(II) ions at pH 5.5, i.e., minimal adsorbent dose (5 mg L-1), impressive resistance to ionic strength (up to 1 mol L-1), and enormous adsorption capacity (1307 mg g(-1)), much higher than those of any of the currently reported sorbents. The adsorption isotherms, kinetics, and effect of ionic strength indicate that an inner-sphere model based on surface complexation is the main mechanism of Pb(II) adsorption on GO-C-60(OH)(22). The high-resolution O1s and Pb4f X-ray photoelectron spectra confirm the strong chelation of Pb(II) ions and suggest the various coordination of Pb(II) ions to the oxygen functional groups. The exceptional properties of GO-C-60(OH)(22), including the possibility of application in micro-quantities, were the basis for the development of the method for ultra-sensitive detection of Pb(II) ions using such micro-analytical technique as total-reflection X-ray fluorescence spectrometry (TXRF). The method allows obtaining an extremely low detection limit of 2.3 pg mL(-1) using a low-power TXRF instrument. Due to the impressive selectivity of the method, the ultra-trace Pb(II) ions can be highly accurately determined in complex matrix samples, including high salinity waters challenging to analyze using other analytical techniques.

Nano-Bi2S3 as a solid sorbent for ultra-sound assisted dispersive micro-solid phase extraction of Hg(ii) ions from surface and sea waters prior to EDXRF determination.