Heavy metals are among important environmental pollutants due to their environmental persistence, toxicity and ability to accumulate in living organisms. The aim of the present study was to ...investigate the levels of aluminium (Al), boron (B), cobalt (Co), chromium (Cr), copper (Cu), and molybdenum (Mo) in plants sampled from Mt. Madra, analysed their distribution characteristics and investigated their origins using Positive Matrix Factorization (PMF) modelling. The multi-point sampling technique was used to collect samples of 26 plants from Madra Mountain at altitudes ranging from 177 m to 1347 m. Inductively-coupled plasma optical emission spectroscopy (ICP-OES) was used for the determination of metals. The metal concentrations (all in terms of mg/kg) determined by ICP-OES are the following sequences (mean ± standard deviation): Al (827.97 ± 198.95) > B (38.49 ± 2.50) > Co (0.74 ± 0.15) > Cr (1.90 ± 0.39) > Cu (7.68 ± 0.73) > Mo (0.51 ± 0.06). Based on the results obtained from the plant samples with the highest concentrations, the following metals were identified: Al (Ajuga orientalis, 4643.57 mg/kg), B (Quercus petraea, 69.25 mg/kg), Co (Ajuga orientalis, 4.23 mg/kg), Cr (Teucrium lamiifolium, 8.64 mg/kg), Cu (Ajuga orientalis, 19.75 mg/kg) and Mo (Ajuga orientalis, 1.07 mg/kg). In conclusion, the results of the source identification analysis conducted by PMF indicated that metal concentrations in the alpine zone have a primarily anthropogenic origin.
•Al and Cr in the plants were significantly different in woody and herbaceous stems.•Plants at different altitudes do not show significant differences in metal values.•Strong positive correlations were found between Al and Co, Cr, and Cu.•Positive Matrix Factorization showed that the metal values in the alpine zone have an anthropogenic origin.
Anemones, specifically the species Anemonia sulcata, are cnidarians that serve as bioindicators in marine ecosystems, indicating the health of the environment and changes in environmental conditions. ...Monitoring anemone populations and studying their well-being and distribution provide valuable insights into marine ecosystem conditions. This study aimed to investigate the impact of the SARS-CoV-2 pandemic on the metal content of Anemonia sulcata. Over a six-year period (2017–2022), twenty specimens of Anemonia sulcata were collected in Tenerife, Spain. The results showed that in 2020, during the two-month lockdown in Spain from March to May when tourism was halted, A. sulcata exhibited the lowest concentrations of various metals studied (Al, Cd, Cu, Fe, Pb, and Zn). This finding suggests that the reduced anthropogenic pressure on the coast due to the absence of tourism significantly decreased pollution levels. Therefore, the study emphasizes the importance of promoting sustainable tourism worldwide. The research highlights that minimizing human impact on coastal areas through responsible tourism practices can effectively reduce pollution in marine ecosystems.
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•A total 120 A. sulcata anemone captured over a period of six years (2017–2022).•Metal concentrations in A. sulcata were lowest just after the pandemic.•Metal contamination in A. sulcata increased after lockdown.
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•Microextraction using DLLME was optimized by factorial design and Doehlert matrix.•Satisfactory recovery values were obtained in surface water samples.•The optimized method provided ...limits of detection between 0.55 and 0.85 μg L-1.•The developed methodology was applied for the analysis of metals in natural and drinking water samples.
In this work, a dispersive liquid–liquid microextraction method combined with inductively coupled plasma optical emission spectrometry was developed to extract and pre-concentrate the trace metals cadmium and lead. Variables such as extracting solvent, dispersive solvent and chelating agent were studied using a univariate design. On the other hand, parameters such as pH, volume of the extracting solvent, volume of the dispersive solvent and concentration of the chelating agent were optimized using a factorial design 24. Doehlert design was used to improve the conditions established in the factorial design. The optimized method consisted of chelating agent concentration of 0.05 % (w/v), 8000 µL of dispersive solvent (ethanol), 600 µL of extracting solvent (chlorobenzene) and a pH of 7.0. Using these conditions, it was obtained a limit of detection of 0.85 and 0.55 µg L-1, enrichment factors of 13.4 and 10 and relative standard deviation of 0.8 and 3.7 % (5 µg L-1, n = 3) for the metals Cd and Pb, respectively. The developed methodology was applied for the analysis of cadmium and lead in natural and drinking water samples.
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The primary objectives of the project are the synthesis of new families of heterocyclic compounds based on 8-hydroxyquinolinenamely: 5-((2-bromoethoxy) methyl) quinolin-8-ol (QC2-Br) ...and 5-((3-bromopropoxy) methyl) quinolin-8-ol (QC3-Br) and their evaluations as inhibitors of acid corrosion (1.0 M HCl).The synthesis of this series of compounds was carried out by a very simple and effective method, but with very good yield and with very good solubility in common organic solvents.The characterization of these new compounds carried out by infrared (FT-IR), nuclear magnetic resonance (1H and 13C NMR) and elementary analysis (EA).The anticorrosion activity was evaluated by gravimetric (WL), electrochemical methods (PDP and EIS) and theoretical studies (DFT, MC and MD). The inhibitors studied adsorbed on the metal surface according to Langmuir isotherm and act on the metal surface as inhibitors mixed type. The thermodynamic parameters show that the two inhibitors adsorb on the metal surface by chemical bonds (chemisorptions).A CPE, Q determined by fit and graphical methods plotted by synthetic data, was utilized.The statistical studies were carried out to confirm the gravimetric tests.Gravimetric solutions were analyzed by Inductively Coupled Plasma-Optical Spectroscopy (ICP-OES) and UV-visible spectrometry (UV-vis). The surface morphology was characterized by Scanning electronic spectroscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and Infrared spectroscopy (FT-IR).The analysis of gravimetric solutions by ICP-OES and UV-visible show that the two inhibitors capable of making chemical bonds with ferric ions and decrease the dissolution of iron in the corrosive solution.The theoretical, experimental results and surface characterization methods show that the two compounds have a good inhibitor of acid corrosion and the inhibitory efficacy exceeds 96% for the two compounds at a concentration of 1 mM.
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•An ultrafast LLE of Cr(III) by choline chloride-thymol deep eutectic solvent.•Extraction efficiencies of Cr(III) exceeded 95% under the optimized conditions.•Reusable deep eutectic ...solvent up to five cycles through stripping process.•Successful speciation analysis of Cr demonstrated in real water samples.•The method was fully validated and ready to use for environmental monitoring.
This work utilized dispersive liquid–liquid extraction as a non-chromatographic separation technique for chromium speciation employing choline chloride-thymol hydrophobic deep eutectic solvent (DES) coupled with inductively coupled plasma optical emission spectroscopy (ICP-OES). The successful separation of chromium species was achieved with the use of a complexing agent, triethanolamine, which facilitated the migration of Cr(III) from the aqueous phase to the DES phase. Optimal conditions for Cr(III) extraction were determined, including a vortex time of 1 min, pH 9.0, triethanolamine concentration of 0.5 mM, and an aqueous-to-extractant volume ratio of 10. These conditions resulted in the extraction efficiency exceeding 95 %. Similarly, stripping of the extracted Cr(III) was accomplished with 90 % efficiency using 0.2 M nitric acid and a contact time of 12 min at room temperature. The consistently high extraction and stripping efficiencies (80–100 %) throughout the five consecutive cycles via this approach indicate the sustainability and ability to reuse choline chloride-thymol DES. The application of the proposed method was also demonstrated through the analysis of various samples with excellent accuracy and precision.
Two shape-persistent covalent cages (CC1 r and CC2 r ) have been devised from triphenyl amine-based trialdehydes and cyclohexane diamine building blocks utilizing the dynamic imine chemistry followed ...by imine bond reduction. The cage compounds have been characterized by several spectroscopic techniques which suggest that CC1 r and CC2 r are 2+3 and 8+12 self-assembled architectures, respectively. These state-of-the-art molecules have a porous interior and stable aromatic backbone with multiple palladium binding sites to engineer the controlled synthesis and stabilization of ultrafine palladium nanoparticles (PdNPs). As-synthesized cage-embedded PdNPs have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and powder X-ray diffraction (PXRD). Inductively coupled plasma optical emission spectrometry reveals that Pd@CC1 r and Pd@CC2 r have 40 and 25 wt% palladium loading, respectively. On the basis of TEM analysis, it has been estimated that as small as ∼1.8 nm PdNPs could be stabilized inside the CC1 r , while larger CC2 r could stabilize ∼3.7 nm NPs. In contrast, reduction of palladium salts in the absence of the cages form structure less agglomerates. The well-dispersed cage-embedded NPs exhibit efficient catalytic performance in the cyanation of aryl halides under heterogeneous, additive-free condition. Moreover, these materials have excellent stability and recyclability without any agglomeration of PdNPs after several cycles.
The dissolution behavior of the Fe-Cr alloys in acidic Na2SO4 solutions was investigated using online inductively coupled plasma-optical emission spectrometry (ICP-OES). The dissolution current ...density of pure Fe measured by spectroscopic analysis shows an anodic Tafel slope of 60 mV decade–1, while the anodic Tafel slope of Fe species in Fe-Cr alloys increases to 120 mV decade–1 with increasing Cr content in the alloy, suggesting that the rate-determining step of the anodic reaction mechanism is dependent on the Cr content. The mass balance on the surface of Fe-6Cr in the active-passive transition indicated that Cr species preferentially dissolved through a salt layer formed on the alloy surface. Some oxidized products that existed in the salt layer in the active region dissolved when the surface changed to the passive state. The anodic reaction mechanism and passivation processes of Fe-Cr alloys, including pure Fe, are discussed quantitatively.
•The benzimidazole and Zn2+ intercalated clay particles were provided.•Active corrosion protection properties of the modified clays were studied.•Self-healing properties were observed by clay ...particles modified with inhibitors.•Clay particles modified with BIA+ and Zn2+ cations showed the best performance.
The objective of this study is to develop and characterize the active protection properties of the benzimidazole (BIA) and zinc cations (Zn2+) intercalated sodium montmorillonite clay particles in an epoxy ester coating. The corrosion protection properties of the samples were studied by an electrochemical impedance spectroscopy (EIS). Results obtained revealed that the Na+ cations presented in the galleries of clay were successfully exchanged with BIA+ and Zn2+ cations. The active corrosion protection properties of the samples were demonstrated by EIS analysis. Promising self-healing and active protection properties were demonstrated by clay particles modified with both BIA+ and Zn2+ cations.
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