Fatigue is a sudden failure of components below the maximum strength of the material when subjected to repeated loading. This paper studies the fatigue behavior of basalt, carbon, and glass ...fibers/epoxy hybrid composites under three‐point flexural loading and a saltwater environment. Five different composite panels were manufactured using the VARTM. The samples were then immersed in a saltwater solution for 60, 120, and 180 days before conducting the tests. Three‐point static and fatigue tests were conducted using UTM as per ASTM D7264‐07 and ASTM D7774‐12. The S‐N and stiffness degradation curves were plotted, and the morphology of the fatigue samples was investigated using SEM. In addition, the ion penetration in the solution was detected with ICP‐OES analysis. The result shows that bending fatigue properties of all composite samples show a degradation as the immersion period increases. This might be due to micro‐hole formation as the ions move from the sample to the saltwater solution.
Highlights
Composite specimens were immersed in a saltwater solution for 2, 4, and 6 months.
Three‐point bending fixture is used for fully reversed fatigue loading (T‐C).
Percentage degradation of fatigue life and stiffness loss increases with the immersion period
SEM image shows delamination, fiber pullout, debonding, and fiber and matrix breakage.
A new GO/Fe3O4@β-lactoglobulin sorbent was prepared for selective extraction of trace Pb(II). The GO/Fe3O4@β-lactoglobulin packed column advantageously permeates samples faster than nascent GO column ...ca. 5 fold. We experimentally demonstrated the developed SPE method for the enrichment of Pb(II) from real samples (tap, river and packaged drinking water) before ICP-OES determination. The sulfhydryl groups of the vicinal cysteine and the carboxylic groups were led to successful chelate formation with Pb(II) ions. The method shows a detection limit of 0.30 ng mL−1 for Pb(II) ion. The prepared sorbent has a surface area and pore volume of 1460.37 m2g−1 and 1.36 ccg−1, respectively. The preconcentration limit and preconcentration factor for Pb(II) was found to be 0.37 μg L−1 and 900, respectively using 3 mL of eluent. At 95% confidence level, the Student's t-test was less than the critical Student's t value (4.303). A coefficients of variation for five replicate measurements is 3.45%, indicates good precision of the method.
•Graphene Oxide/Fe3O4@β-lactoglobulin composite was prepared.•The composite shows good adsorption of Hg(II) i.e. 150 mg/g.•Effectively extract trace Pb (II) ions from complex matrix.•Selectively quantify Pb(II) in real sample analysis.
The accumulation of heavy metals in fish has been extensively studied and well documented. However, the research has been mainly focused on the muscle tissue, while the distribution patterns among ...other tissues, such as liver and gills, have been mostly neglected. Within the present study, the concentrations of Ag, Al, As, B, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sr, Zn and Li in the muscle, gills, liver and intestine of the sterlet (Acipenser ruthenus) from the Danube River have been assessed by using the inductively-coupled plasma optical spectrometry. The analysis has revealed a high degree of differential accumulation of the studied heavy metals and trace elements in the tissues of the Danube sterlet. Liver appeared to be the main heavy metal storage tissue, while the lowest levels of analyzed metals were found in muscles. Heavy metal concentrations in the muscle were at acceptable levels for human consumption, except partly for cadmium. We conclude that, in order to enable a more efficient control of contaminants in fish products, there is an apparent need to resolve the problem of lack of legal limits for many metals in European legislation.
We report a simple and effective electrochemical method to remove Fe impurities from commercial KOH electrolyte. We therefore utilize a MoS2 catalyst deposited on porous Ni foam as both the anode and ...cathode in a two-electrode electrolysis setup. After 12 h of constant galvanostatic electrolysis at 100 mA, the Fe impurities from the KOH electrolyte were successfully removed, as confirmed by means of inductively coupled plasma optical emission spectroscopy analysis. In the purified KOH, a Ni–Co3O4 composite oxide catalyst showed no Fe-induced activation. In contrast, we directly observed the uptake of Fe on the Ni–Co3O4 catalyst from the nontreated electrolyte during catalyst operation using a coupled spectroelectrochemical setup. Interestingly, we further identified an influence on the dissolution behavior of Ni and Co in the presence of Fe impurities. Whereas hitherto mainly the activation effect of Fe impurities has been discussed, we hereby show that they additionally suppress corrosion under reaction conditions. Using our fast and low-cost method for the purification of large amounts of electrolyte, catalyst materials can be widely studied without these additional effects induced by Fe impurities in commercial KOH.
This study introduces a novel method for preconcentrating As, Cu, and Pb from seawater samples using manganese oxide octahedral molecular sieve (OMS-2), as a sorbent, and the analysis by Inductively ...Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The OMS-2 nanomaterial was synthesized and characterized using X-ray diffraction and scanning electron microscopy, revealing a crystallite size of 20.9 nm and a typical needle-like morphology of cryptomelane structure. To optimize the ICP-OES operating conditions and the preconcentration process, a central composite design was used. The optimal conditions for ICP-OES analyses were 1200 W and 0.7 L min−1 for the levels of the radio frequency potential (RF) and nebulization gas flow rate, respectively. The optimal conditions for the adsorption process were achieved at a pH of 6.5, 30 mg of OMS-2, and 35 min of stirring time, in the presence of the sample matrix. The enrichment factors obtained were 66, 45, and 21, and a limit of detection of 0.3, 0.1, and 2.1 μg L−1 for As, Cu, and Pb, respectively. The recovery tests ranged from 80 % to 120 %. The method was successfully applied to determine As, Cu, and Pb in seawater samples.
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•A new material was applied for the determination of As, Cu, and Pb.•The factors affecting the separation were optimized using chemometrics.•Very sensitive method was achieved for As, Cu, and Pb determination.
•Multi-elemental contents of Sechium edule fruits were determined.•LDA, kNN, PLS-DA and SVM were used for classification.•Chemometric analysis is effective in distinguishing the origin of fruits.•LDA ...classification model was simplified by forward stepwise selection of variables.•Ca, Ba, Cu, Mn, Na, Sr, and Zn contents allowed above 90% correct classification.
This paper describes the determination and evaluation of the major and trace element composition (Al, As, Ba, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Pb, Sr and Zn) of Sechium edule (Jacq) Swartz fruits collected from four different places of production in Corrientes province, Argentina. Element concentrations were determined by using inductively coupled plasma optical emission spectrometry (ICP OES) after microwave digestion. The accuracy was confirmed with standard reference material of spinach leaves (NIST, 1570a) and spiking tests. Principal component analysis (PCA), linear discriminant analysis (LDA), k-nearest neighbors (kNN), partial least square-discriminant analysis (PLS-DA) and support vector machine (SVM) were applied to the results for discriminating the geographical origin of S. edule fruits. Finally, the LDA method was found to perform best with up to 90% accuracy rate based on the following elements: Ca, Ba, Cu, Mn, Na, Sr, and Zn.
The paper presents an independent application of two hyphenated techniques, wherein an identical chromatographic system i.e. high performance liquid chromatography (HPLC) was coupled to microwave ...induced plasma optical emission spectrometry (MIP OES) or inductively coupled plasma optical emission spectrometry (ICP OES). A cation–exchange column and a mobile phase based on pyridine–2,6–dicarboxylic acid (PDCA) were employed to separate Fe(II) and Fe(III) within 300 s. Additionally, two methods of sample preparation were employed. Optimization and validation of both methods were conducted parallel. The applicability was presented with different sample matrix types: post–glacial sediments, archaeological pottery, soils located in the proximity of industry wastes disposal site, river sediments and yerba mate (Ilex paraguariensis). Obtained results were compared in terms of the excitation source (microwave induced or inductively coupled) and supplied gas (nitrogen or argon). The research introduces HPLC–MIP OES for iron speciation analysis and its applicability were critically evaluated with HPLC–ICP OES.
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•The optical emission detectors with different plasma sources has been applied for iron species determination.•The hyphenated techniques HPLC–MIP–OES and HPLC–ICP–OES has been optimized and validated.•The application of speciation analysis has been elaborated for different matrixes.
Background
Food and drug packaging materials are an integral part of our everyday life. Noxious elements can inadvertently be included in packaging materials in various stages of their production. ...Adulterants, adhesives, colorants and heavy metal interference are the common sources of contamination in food packaging materials. Heavy metal toxicity has far-reaching ill effects on living organisms. The present study aimed at qualitatively and quantitatively analysing heavy metal content of various materials that are used for food and drug packaging in India.
Methods
The qualitative detection was done by rapid assay and heavy metals were quantified with the help of inductively coupled plasma-optical emission spectrometry (ICP-OES). A total of thirteen types of food and drug packaging materials were procured from local market and analysed for four heavy metals
viz. arsenic (As), vanadium (V), mercury (Hg) and cadmium (Cd). The concentration of each heavy metal in the samples was compared with the permissible values published by the European Council.
Results
Heavy metals were qualitatively detected in ten out of thirteen samples. Among the ten samples mercury and arsenic were detected the most followed by cadmium and vanadium. Quantitative estimation by ICP-OES showed presence of vanadium and cadmium in ten samples and arsenic and mercury in all the thirteen samples above the permissible range.
Conclusions
The notable elevation in mercury concentration, followed by cadmium, arsenic and vanadium registering the least, presents a potential health hazard to consumers and compromises the food quality.
A simple and highly efficient method for the determination of highly toxic arsenic species using non-covalently aminated silica is proposed. The polyamines including poly(hexamethyleneguanidine), ...poly(4,9-dioxadodecane-1,12-guanidine), hexadimethrine, and poly(diallyldimethylammonium) were tested as silica modifiers. The prepared adsorbents allow effective preconcentration of anionic species of arsenic from aqueous solutions. It was found that As(V) can be quantitatively extracted from solutions at pH 4.5–7.0 by the anion exchange mechanism in less than 5 min, while neutral at this pH As(III) was not adsorbed at these conditions. A reaction with 2,3-dimercapto-1-propanesulphonic acid, which resulted in the formation of the negatively charged complex of As(III) with adsorbents was used for its quantitative extraction from solutions with a pH of 3.5–6.5. A system of two cartridges filled with poly(diallyldimethylammonium) modified silica and the on-line reaction of As(III) with 2,3-dimercapto-1-propanesulphonic acid proceeding between the cartridges was used for separate preconcentration and determination of As(V) and As(III) at pH 5. The proposed method was used for four-year monitoring of natural water pollution by arsenic in the area of residence of the indigenous peoples of Tyva Republic (Russia).
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•Silica modified with polyamines was used for separation of As(V)/As(III) at pH 5.•As(III) was extracted as a complex with 2,3-dimercapto-1-propanesulphonic acid.•Quantitative extraction of As(III) was attained at the ratio As:DMPS more than 1:10.•The preconcentration factor for As(V) reached 300, for As(III) 400.•Sequentially connected cartridges were proposed for arsenic speciation and monitoring of natural water.
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