scholarly journals Trace Metal Detection in Aqueous Reservoirs Using Stilbene Intercalated Layered Rare-Earth Hydroxide Tablets

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Solomon Omwoma
Keyword(s):  
Trace Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Aqueous Media ◽  
Mitigation Measures ◽  
Metal Ion Analysis ◽  
Gradual Process ◽  
Metal Detection ◽  
Trace Metal Detection ◽  
High Concentrations

Contamination of aquatic reservoirs with metal ions is a slow gradual process that is not easy to detect. Consequences of the metal ions, especially the ones with high atomic numbers (heavy metals) at high concentrations, are severe and irreversible in aquatic reservoirs. As such, early detection mechanisms, especially at trace concentration, are essential for mitigation measures. In this work, a new, robust, and effective tool for trace metal detection and monitoring in aqueous solutions has been developed. Tablets (1 mm thick and similar to medicinal tablets) were manufactured from a powder comprising stilbene intercalated into gallery spaces of lanthanide-containing layered double hydroxides. The tablets were placed in a water column having different concentrations of Pb2+ and Cu2+ ions, and the water was allowed to flow for 45 minutes at a flow rate of 100 ml/s. Thereafter, the tablets were dried and made to powder, and their phosphorescence was measured. The gradual stilbene phosphorescence turnoff in the tablets from various concentrations of metal ions was correlated with sorption amounts. The tablets were able to detect effectively metal ions (up to Pb2+ 1.0 mmol/L and Cu2+ 5.0 mmol/L) in the aqueous media. As such, the concentrations of Pb2+ and Cu2+ ions at trace levels were determined in the test solutions. This method provides a real-time metal ion analysis and does not involve sampling of water samples for analysis in the laboratory.

The transfer and persistence of metals in latent fingermarks

2021 ◽  
Author(s):  
Rhiannon Boseley ◽  
Daryl Howard ◽  
Mark Hackett ◽  
Simon Lewis
Keyword(s):  
Trace Metal ◽  
Metal Ions ◽  
Forensic Science ◽  
Spatial Resolution ◽  
Metal Ion ◽  
Activity Level ◽  
X Ray ◽  
Trace Metal Ions ◽  
Gun Barrel ◽  
Trace Metal Detection

In forensic science, knowledge and understanding of material transfer and persistence is inherent to the interpretation of trace evidence and can provide vital information on the activity level surrounding a crime. Detecting metal ions in fingermark residue has long been of interest in the field of forensic science, due to the possibility of linking trace metal ion profiles to prior activity with specific metal objects (e.g. gun or explosive handling). Unfortunately, the imaging capability to visualise trace metal ions at sufficient spatial resolution to determine their distribution within a fingermark (micron level) was not previously available. Here, we demonstrate for the first time transfer and persistence of metals in fingermarks, at micron spatial resolution, using synchrotron sourced x-ray fluorescence microscopy. Fingermarks were taken before and after brief handling of a gun barrel, ammunition cartridge case and party sparkler to demonstrate the transfer of metals. The results reveal increased metal content after contact with these objects, and critically, a differential pattern of metal ion increase was observed after handling different objects. Persistence studies indicate that these metals are removed as easily as they are transferred, with a brief period of hand washing appearing to successfully remove metallic residue from subsequent fingermarks. Preliminary work using x-ray absorption near edge structure spectroscopic mapping highlighted the potential use of this technique to differentiate between different chemical forms of metals and metal ions in latent fingermarks. It is anticipated that these findings can now be used to assist future work for the advancement of trace metal detection tests and fingermark development procedures

Efficient Preconcentration of Cu2+, Zn2+ and Fe3+ with an Agarose-Schiff Base Sorbent

2007 ◽  
Vol 72 (7) ◽  
pp. 908-916 ◽  
Author(s):  
Payman Hashemi ◽  
Hatam Hassanvand ◽  
Hossain Naeimi
Keyword(s):  
Schiff Base ◽  
Metal Ions ◽  
Metal Ion ◽  
Good Accuracy ◽  
Kinetic Studies ◽  
Sample Volume ◽  
Effects Of Ph ◽  
Glass Column ◽  
High Concentrations ◽  
Ph Range

Sorption and preconcentration of Cu2+, Zn2+ and Fe3+ on a salen-type Schiff base, 2,2'- [ethane-1,2-diylbis(nitrilomethylidyne)]bis(2-methylphenol), chemically immobilized on a highly crosslinked agarose support, were studied. Kinetic studies showed higher sorption rates of Cu2+ and Fe3+ in comparison with Zn2+. Half-times (t1/2) of 31, 106 and 58 s were obtained for sorption of Cu2+, Zn2+ and Fe3+ by the sorbent, respectively. Effects of pH, eluent concentration and volume, ionic strength, buffer concentration, sample volume and interferences on the recovery of the metal ions were investigated. A 5-ml portion of 0.4 M HCl solution was sufficient for quantitative elution of the metal ions from 0.5 ml of the sorbent packed in a 6.5 mm i.d. glass column. Quantitative recoveries were obtained in a pH range 5.5-6.5 for all the analytes. The volumes to be concentrated exceeding 500 ml, ionic strengths as high as 0.5 mol l-1, and acetate buffer concentrations up to 0.3 mol l-1 for Zn2+ and 0.4 mol l-1 for Cu2+ and Fe3+ did not have any significant effect on the recoveries. The system tolerated relatively high concentrations of diverse ions. Preconcentration factors up to 100 and detection limits of 0.31, 0.16 and 1.73 μg l-1 were obtained for Cu2+, Zn2+ and Fe3+, respectively, for their determination by a flame AAS instrument. The method was successfully applied to the metal ion determinations in several river water samples with good accuracy.

scholarly journals Anodic Stripping Voltammetry with the Hanging Mercury Drop Electrode for Trace Metal Detection in Soil Samples

Chemosensors ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 107
Author(s):  
Kequan Xu ◽  
Clara Pérez-Ràfols ◽  
Amine Marchoud ◽  
María Cuartero ◽  
Gastón A. Crespo
Keyword(s):  
Metal Ions ◽  
Limit Of Detection ◽  
Anodic Stripping Voltammetry ◽  
Stripping Voltammetry ◽  
Hanging Mercury Drop Electrode ◽  
Mercury Drop Electrode ◽  
Redox Active ◽  
Active Metal ◽  
Metal Detection ◽  
Trace Metal Detection

The widely spread use of the hanging mercury drop electrode (HMDE) for multi-ion analysis is primarily ascribed to the following reasons: (i) excellent reproducibility owing to the easy renewal of the electrode surface avoiding any hysteresis effect (i.e., a new identical drop is generated for each measurement to be accomplished); (ii) a wide cathodic potential window originating from the passive hydrogen evolution and solvent electrolysis; (iii) the ability to form amalgams with many redox-active metal ions; and (iv) the achievement of (sub)nanomolar limits of detection. On the other hand, the main controversy of the HMDE usage is the high toxicity level of mercury, which has motivated the scientific community to question whether the HMDE deserves to continue being used despite its unique capability for multi-metal detection. In this work, the simultaneous determination of Zn2+, Cd2+, Pb2+, and Cu2+ using the HMDE is investigated as a model system to evaluate the main features of the technique. The analytical benefits of the HMDE in terms of linear range of response, reproducibility, limit of detection, proximity to ideal redox behavior of metal ions and analysis time are herein demonstrated and compared to other electrodes proposed in the literature as less-toxic alternatives to the HMDE. The results have revealed that the HMDE is largely superior to other reported methods in several aspects and, moreover, it displays excellent accuracy when simultaneously analyzing Zn2+, Cd2+, Pb2+, and Cu2+ in such a complex matrix as digested soils. Yet, more efforts are required towards the definitive replacement of the HMDE in the electroanalysis field, despite the elegant approaches already reported in the literature.

Development of calix[4]arenes modified at their narrow- and wider-rims as potential metal ions sensor layers for microcantilever sensors: further studies

2021 ◽  
Author(s):  
Paris E. Georghiou ◽  
Shofiur Rahman ◽  
Yousif Assiri ◽  
Gopi Kishore Valluru ◽  
Melita Menelaou ◽  
...  
Keyword(s):  
Metal Ions ◽  
Metal Ion ◽  
Computational Study ◽  
Aqueous Media ◽  
Experimental Studies ◽  
Ionic Species ◽  
Alkoxy Group ◽  
Self Assembled Monolayers ◽  
Microcantilever Sensors ◽  
Assembled Monolayers

The development of a microcantilever (MCL) sensing device capable of simultaneously detecting several metal ionic species in aqueous media with low limits of detection requires a variety of sensing layers which are ion-specific. Calix[4]arenes are robust molecules which can be easily modified and have been extensively studied for their ion binding properties. They are also capable of forming self-assembled monolayers (SAMs) onto the gold layers of MCLs and are capable of detecting various metal ions with different anionic counterions in aqueous solutions. In this paper we report on the effect of the alkoxy group in the narrow rim [O-(alkoxycarbonyl)methoxy] substituents of bimodal calix[4]arenes which have been used as metal ion MCL sensing layers, using classical solution state experimental studies. A DFT computational study to compare the experimental results with several metal ions is also reported herein.

Trace Metal Detection in Natural Water

1999 ◽  
pp. 341-344
Author(s):  
A. Taglauer ◽  
R. Niessner ◽  
W. Von Der Linden ◽  
V. Dose ◽  
E. Taglauer
Keyword(s):  
Trace Metal ◽  
Natural Water ◽  
Metal Detection ◽  
Trace Metal Detection

Metal ion complexation by soft nanoparticles: the effect of Ca2+ on electrostatic and chemical contributions to the Eigen-type reaction rate

2015 ◽  
Vol 12 (2) ◽  
pp. 130 ◽  
Author(s):  
Raewyn M. Town
Keyword(s):  
Humic Acid ◽  
Trace Metal ◽  
Metal Ions ◽  
Electrostatic Field ◽  
Metal Binding ◽  
Metal Ion ◽  
Bulk Solution ◽  
Trace Metal Ions ◽  
Charged Nanoparticles ◽  
Soft Nanoparticles

Environmental context The speciation of trace metals in the environment is often dominated by complexation with natural organic matter such as humic acid. Humic acid is a negatively charged soft nanoparticle and its electrostatic properties play an important role in its reactivity with metal ions. The presence of major cations, such as Ca2+, can decrease the effective negative charge in the humic acid particle body and thus modify the chemodynamics of its interactions with trace metal ions. Abstract The effect of Ca2+ on the chemodynamics of PbII complexation by humic acid (HA) is interpreted in terms of theory for permeable charged nanoparticles. The effect of the electrostatic field of a negatively charged nanoparticle on its rate of association with metal cations is governed by the interplay of (i) conductive enhancement of the diffusion of cations from the medium to the particle and (ii) ionic Boltzmann equilibration with the bulk solution leading to accumulation of cations in the particle body. Calcium ions accumulate electrostatically within the HA body and thus lower the magnitude of the negative potential in the particle. For the case where trace metal complexation takes place in a medium in which the particulate electrostatic field is set by pre-equilibration in the electrolyte, the lability of Pb-HA complexes is found to be significantly increased in Ca2+-containing electrolyte, consistent with the predicted change in particle potential. Furthermore, the rate-limiting step changes from diffusive supply to the particle body in a 1–1 electrolyte, to inner-sphere complexation in a 2–1 electrolyte. The results provide insights into the electrostatic and covalent contributions to the thermodynamics and kinetics of trace metal binding by soft nanoparticles.

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