scholarly journals Assessment of labilities of metal complexes with the dynamic ion exchange technique

2019 ◽  
Vol 16 (3) ◽  
pp. 151
Author(s):  
Federico Quattrini ◽  
Josep Galceran ◽  
Carlos Rey-Castro ◽  
Jaume Puy ◽  
Claude Fortin
Keyword(s):  
Ion Exchange ◽  
Natural Waters ◽  
Breakthrough Curves ◽  
Short Exposure ◽  
Metal Bioavailability ◽  
Operation Conditions ◽  
The Impact ◽  
Free Metal ◽  
Metal Ligand ◽  
Exchange Technique

Environmental contextIn natural waters, the impact of metals on biota is modulated by their binding with ligands. Ion-exchange techniques can provide information about metal-ligand complexes in solution, which can be linked to metal bioavailability in natural waters. We investigate modelling approaches to interpreting data from ion-exchange experiments to help elucidate the contribution of a particular complex to the overall metal uptake. AbstractThe dynamic ion exchange technique (DIET) is proposed to provide speciation information, which can be used to establish links with metal bioavailability in natural waters. The experimental setup consists of a few milligrams of a sulfonic acid type ion exchange resin packed in a plastic microcolumn that is coupled to a peristaltic pump for a sample to interact with the resin which is subsequently eluted. The evolution of both the accumulated number of moles in the resin and the concentration of the effluent can provide information on the dissociation of different metal-ligand complexes when compared with the transport properties. This information can be converted into the lability degree of a given complex or the DIET concentration cDIET, which accounts for the labile fraction contributing to the metal accumulation by the resin column at the operation conditions. cDIET can be extended to columns containing chelating resins (such as those with Chelex) or to chromatography. A comprehensive modelling of the involved phenomena (such as diffusion, advection, reaction kinetics and electrostatic partitioning) leads to the quantitative interpretation of the accumulation time series (accumulation curves) or effluent evolution (breakthrough curves). Particularly simple analytical expressions can be used for short exposure times, when a (quasi) steady-state is attained. These models have been checked against the results from complexes of Cu and Ni with ligands, such as ethylenediamine, and ethylenediaminetetraacetic, iminodiacetic, glutamic, salicylic, malonic and malic acids, which yield complexes with contrasting charges. Caution is advised when estimating the free metal fraction from DIET measurements, as cDIET and the free metal concentration can be considered to be equal only in the case of extremely inert complexes.

scholarly journals Determination of the free-ion concentration of rare earth elements by an ion-exchange technique: implementation, evaluation and limits

2016 ◽  
Vol 13 (3) ◽  
pp. 478 ◽  
Author(s):  
Sébastien Leguay ◽  
Peter G. C. Campbell ◽  
Claude Fortin
Keyword(s):  
Ion Exchange ◽  
Natural Organic Matter ◽  
Metal Ion ◽  
Exchange Resin ◽  
Ion Exchange Resin ◽  
Ion Concentration ◽  
Free Ion ◽  
Free Metal ◽  
Free Metal Ion ◽  
Exchange Technique

Environmental context The lanthanides are a group of heavy elements (from lanthanum to lutetium) increasingly used in many electronic consumer products and little is known about their environmental mobility and toxicity. In natural systems, these elements will bind to natural organic matter but metal toxicity is usually defined by the free metal ion concentration. Here, we propose a method based on sample equilibration with an ion-exchange resin to measure the free lanthanide ion concentration in the presence of natural organic matter. Abstract An ion-exchange technique that employs a polystyrene sulphonate ion-exchange resin was developed for determining environmentally relevant free-ion concentrations of Ce, Eu, La and Nd. Owing to the high affinity of rare earth elements (REE) for the selected resin, this method requires the addition of an inert salt to increase the concentration of the counter-ions (i.e. cations that are exchanged with REE bound to the resin). The use of a batch equilibration approach to calibrate the resin allowed the implementation of the ion-exchange technique at reasonably low ionic strength (I = 0.1M). Several ligands were used to test the selectivity of the method, which proved to be highly selective for the free metal ion in presence of the tested cationic and anionic complexes (REE–nitrate, REE–malic acid and REE–nitrilotriacetic acid systems) and operational for very low proportions of REE3+, owing to the strong REE–resin interactions. The ion-exchange technique was also implemented to determine [Eu]inorg in the presence of natural humic matter (Suwannee River Humic Acid) and the results were compared with those obtained using equilibrium dialysis and those calculated with chemical equilibrium models. At pH 4.00, the measured [Eu]inorg values were in fairly good agreement with those predicted with the Windermere Humic Aqueous Model and Stockholm Humic Model, whereas the Non-Ideal Competitive Absorption model appeared to underestimate the [Eu]inorg. However, the inorganic europium concentrations were strongly underestimated (4 < [Eu]inorg, IET/[Eu]inorg, calc < 18) with the three prediction models at higher pH (5.3 and 6.2).

Ion-exchange technique (IET) for measuring Cu2+, Ni2+ and Zn2+ activities in soils contaminated with metal mixtures

2017 ◽  
Vol 14 (1) ◽  
pp. 55 ◽  
Author(s):  
D. M. Schwertfeger ◽  
W. H. Hendershot
Keyword(s):  
Organic Matter ◽  
Ion Exchange ◽  
Metal Binding ◽  
Mean Squared Error ◽  
Metal Speciation ◽  
Ion Exchange Resin ◽  
Metal Bioavailability ◽  
Soil Extracts ◽  
Metal Mixtures ◽  
Exchange Technique

Environmental contextTerrestrial environments receiving trace metal contaminants are often impacted by more than one metal. This study demonstrates the adaptation of an ion-exchange technique to simultaneously obtain Cu2+, Ni2+ and Zn2+ activities in soil extracts. These measurements can be used to better understand and predict the behaviour and bioavailability of soil metals in metal–mixture contamination scenarios. AbstractReliable estimates of metal speciation are critical for predicting metal bioavailability and the toxicological effects of metal mixtures in the soil environment; however, simultaneous measurements of metal free ion activities in complex matrices pose a challenge. Although speciation models maybe useful, the uncertainty of metal binding to natural organic matter requires that such models be validated with empirical data. In this study, an ion-exchange resin technique (IET) was adapted for the analysis of Cu2+, Ni2+ and Zn2+ in soil extracts. The analysis was performed with three different soil types spiked with single and multiple metal additions to obtain a range of metal concentrations and combinations. Method detection limits of 0.006, 0.04 and 0.05µM for Cu2+, Ni2+ and Zn2+ were achieved. The values obtained by IET were comparable with those estimated by Visual MINTEQ, giving a root mean squared error of 0.21, 0.30 and 0.34 (n=30) for the Cu, Ni and Zn data. The Cu2+ activities obtained by IET were within an order of magnitude of those obtained by a Cu ion-selective electrode, being on average 6-fold greater, with better agreement occurring in samples having lower organic matter contents. The resulting soil metal speciation data revealed that the partitioning of soil Cu to the potentially bioavailable Cu2+ pool differed in the binary mixture with Ni compared with the single-metal Cu treatments. These data can be used to assess metal bioavailability and aid in the interpretation of ecotoxicological effects observed in soils where multiple metals are a concern.

scholarly journals The Influence of Concentration and Temperature on the Membrane Resistance of Ion Exchange Membranes and the Levelised Cost of Hydrogen from Reverse Electrodialysis with Ammonium Bicarbonate

Membranes ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 135
Author(s):  
Yash Dharmendra Raka ◽  
Robert Bock ◽  
Håvard Karoliussen ◽  
Øivind Wilhelmsen ◽  
Odne Stokke Burheim
Keyword(s):  
Ion Exchange ◽  
Waste Heat ◽  
Ammonium Bicarbonate ◽  
Operating Efficiency ◽  
Membrane Thickness ◽  
Ion Exchange Membranes ◽  
Reverse Electrodialysis ◽  
Ohmic Resistance ◽  
Production Of Hydrogen ◽  
The Impact

The ohmic resistances of the anion and cation ion-exchange membranes (IEMs) that constitute a reverse electrodialysis system (RED) are of crucial importance for its performance. In this work, we study the influence of concentration (0.1 M, 0.5 M, 1 M and 2 M) of ammonium bicarbonate solutions on the ohmic resistances of ten commercial IEMs. We also studied the ohmic resistance at elevated temperature 313 K. Measurements have been performed with a direct two-electrode electrochemical impedance spectroscopy (EIS) method. As the ohmic resistance of the IEMs depends linearly on the membrane thickness, we measured the impedance for three different layered thicknesses, and the results were normalised. To gauge the role of the membrane resistances in the use of RED for production of hydrogen by use of waste heat, we used a thermodynamic and an economic model to study the impact of the ohmic resistance of the IEMs on hydrogen production rate, waste heat required, thermochemical conversion efficiency and the levelised cost of hydrogen. The highest performance was achieved with a stack made of FAS30 and CSO Type IEMs, producing hydrogen at 8.48× 10−7 kg mmem−2s−1 with a waste heat requirement of 344 kWh kg−1 hydrogen. This yielded an operating efficiency of 9.7% and a levelised cost of 7.80 € kgH2−1.

An ion-exchange technique for concentrating ammonia from small volumes of seawater

1981 ◽  
Vol 10 (2) ◽  
pp. 159-164 ◽  
Author(s):  
Ronald T. Riley ◽  
Michael C. Mix
Keyword(s):  
Ion Exchange ◽  
Exchange Technique

ChemInform Abstract: Catalytic Asymmetric Dihydroxylation of Olefins with New Catalysts: The First Example of Heterogenization of OsO42- by Ion-Exchange Technique.

ChemInform ◽  
2010 ◽  
Vol 33 (4) ◽  
pp. no-no
Author(s):  
Boyapati M. Choudary ◽  
Naidu S. Chowdari ◽  
Mannepalli L. Kantam ◽  
Kondapuram V. Raghavan
Keyword(s):  
Ion Exchange ◽  
Asymmetric Dihydroxylation ◽  
Catalytic Asymmetric ◽  
Exchange Technique

Ion-exchange breakthrough curves for single and multi-metal systems using marine macroalgae Pelvetia canaliculata as a natural cation exchanger

2015 ◽  
Vol 269 ◽  
pp. 359-370 ◽  
Author(s):  
Fabíola V. Hackbarth ◽  
Franciélle Girardi ◽  
João C. Santos ◽  
Antônio Augusto U. de Souza ◽  
Rui A.R. Boaventura ◽  
...  
Keyword(s):  
Ion Exchange ◽  
Cation Exchanger ◽  
Breakthrough Curves ◽  
Marine Macroalgae

scholarly journals How Dead Wood in the Forest Decreases Relaxation? The Effects of Viewing of Dead Wood in the Forest Environment on Psychological Responses of Young Adults

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 871
Author(s):  
Emilia Janeczko ◽  
Ernest Bielinis ◽  
Ulfah Tiarasari ◽  
Małgorzata Woźnicka ◽  
Wojciech Kędziora ◽  
...  
Keyword(s):  
Young Adults ◽  
Dead Wood ◽  
Short Exposure ◽  
Managed Forests ◽  
Environment Impact ◽  
Forest Environment ◽  
Dead Trees ◽  
Before And After ◽  
Positive Feelings ◽  
The Impact

The intensity of the neutral environment impact on humans may be determined by specific features of space, including dead wood occurrence. Dead wood is claimed to be disliked by the public because it reduces the scenic beauty and recreational values of the forest. The attractiveness of a forest with dead wood may be determined by its variants. Much is known about the preference for landscape with dead wood, but there is little information available about how such a landscape affects a person’s mental relaxation, improves mood, increases positive feelings, levels of vitality, etc. Hence, the aim of our research was to investigate the psycho-logical relaxing effects of short 15-min exposures to natural and managed forests with dead wood. In the study, three areas within the Białowieża Primeval Forest were used to measure the impact of different types of forest with dead wood (A: forest reserve with dead wood subject to natural decomposition processes; B: managed forest with visible cut wood and stumps; C: man-aged forest with dead trees from bark beetle outbreak standing) on human psychological relaxation in a randomized experiment. The participants of the experiment were forty-one young adults aged 19–20. Each respondent experienced each type of forest at intervals visiting it. Four psychological questionnaires were used in the project (Profile of Mood States (POMS), Positive and Negative Affect Schedule (PANAS), Subjective Vitality Scale (SVS), and Restorative Outcome Scale (ROS)) before and after the short exposure to the forest were evaluated. The results show that a forest landscape with dead wood affects the human psyche, and the relaxing properties of such a landscape are better in a protected forest with natural, slow processes of tree dieback than those obtained in managed forests

Mistuning and Damping of a Radial Turbine Wheel. Part 1: Fundamental Analyses and Design of Intentional Mistuning Pattern

2021 ◽  
Author(s):  
Alex Nakos ◽  
Bernd Beirow ◽  
Arthur Zobel
Keyword(s):  
High Stress ◽  
Forced Response ◽  
Experimental Investigations ◽  
Detailed Knowledge ◽  
Turbine Wheel ◽  
Operation Conditions ◽  
Radial Turbine ◽  
Influence Coefficients ◽  
Modes Of Vibration ◽  
The Impact

Abstract The radial turbine impeller of an exhaust turbocharger is analyzed in view of both free vibration and forced response. Due to random blade mistuning resulting from unavoidable inaccuracies in manufacture or material inhomogeneities, localized modes of vibration may arise, which involve the risk of severely magnified blade displacements and inadmissibly high stress levels compared to the tuned counterpart. Contrary, the use of intentional mistuning (IM) has proved to be an efficient measure to mitigate the forced response. Independently, the presence of aerodynamic damping is significant with respect to limit the forced response since structural damping ratios of integrally bladed rotors typically take extremely low values. Hence, a detailed knowledge of respective damping ratios would be desirable while developing a robust rotor design. For this, far-reaching experimental investigations are carried out to determine the damping of a comparative wheel within a wide pressure range by simulating operation conditions in a pressure tank. Reduced order models are built up for designing suitable intentional mistuning patterns by using the subset of nominal system modes (SNM) approach introduced by Yang and Griffin [1], which conveniently allows for accounting both differing mistuning patterns and the impact of aeroelastic interaction by means of aerodynamic influence coefficients (AIC). Further, finite element analyses are carried out in order to identify appropriate measures how to implement intentional mistuning patterns, which are featuring only two different blade designs. In detail, the impact of specific geometric modifications on blade natural frequencies is investigated.

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