Ion-exchange procedures for the estimation of (i) total ionic concentration, (ii) chlorides and (iii) sulphates in natural waters

Although the majority of publications on extant nonmarine ostracode species in North America are concerned with lacustrine settings, many species that are potentially valuable as indicators of water quality changes live in non-lacustrine settings. Ostracode distributions in 157 springs, wetlands and streams in the United States are examined here in order to assess 1) species richness, 2) association with physical and chemical parameters of their habitats and 3) the presence of potentially useful biomonitors and environmental sentinels. The 157 non-lacustrine sites are a subset of a large database (North American Non-marine Ostracode Database: NANODe version 1) consisting of 611 mostly lacustrine sites with ostracode species, presence-absence data, hydrochemistry and climate data (Forester et al., in review). Of the 89 species represented in NANODe version 1, 51 species are found in springs, 59 species are found in wetlands and only 15 species are found in streams. Many species are found in at least two of these habitats and some in all three. Principal Components Analysis of these 157 sites indicates that 71% of the variance is explained by salinity (total ionic concentration), alkalinity and temperature, a result consistent with previously published analyses of natural water. Cluster analysis shows that spring species are most strongly tied to temperature, whereas wetlands and streams are most strongly tied to ionic composition. Three species are found to be potentially valuable biomonitors: Cavernocypris wardi in springs, Fabaeformiscandona rawsoni in wetlands and Physocypria globula in streams.

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Ion-exchange chromatography of mono- and divalent cations in natural waters on a weak-acid anion-exclusion column

Journal of Chromatography A ◽

10.1016/s0021-9673(98)00031-4 ◽

1998 ◽

Vol 804 (1-2) ◽

pp. 179-186 ◽

Cited By ~ 10

Author(s):

Kazuhiko Tanaka ◽

Kazutoku Ohta ◽

Paul R Haddad ◽

James S Fritz

Keyword(s):

Ion Exchange ◽

Natural Waters ◽

Divalent Cations ◽

Weak Acid ◽

Ion Exchange Chromatography ◽

Exchange Chromatography ◽

Acid Anion ◽

Anion Exclusion

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Automated two-column ion exchange system for determination of the speciation of trace metals in natural waters

Analytical Chemistry ◽

10.1021/ac00181a005 ◽

1989 ◽

Vol 61 (6) ◽

pp. 525-529 ◽

Cited By ~ 48

Author(s):

Yan. Liu ◽

J. D. Ingle

Keyword(s):

Trace Metals ◽

Ion Exchange ◽

Natural Waters ◽

Exchange System

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Asymmetric electroosmotic pumping across porous media sandwiched with perforated ion-exchange membranes

Faraday Discussions ◽

10.1039/c6fd00248j ◽

2017 ◽

Vol 199 ◽

pp. 175-193 ◽

Cited By ~ 2

Author(s):

A. Yaroshchuk ◽

E. E. Licón ◽

E. K. Zholkovskiy ◽

M. P. Bondarenko ◽

T. Heldal

Keyword(s):

Ion Exchange ◽

Concentration Polarization ◽

Average Distance ◽

Ionic Concentration ◽

Hydraulic Permeability ◽

Debye Screening Length ◽

Ion Exchange Membranes ◽

Lateral Direction ◽

Non Linear ◽

Electroosmotic Pumps

To have non-zero net flow in AC electroosmotic pumps, the electroosmosis (EO) has to be non-linear and asymmetric. This can be achieved due to ionic concentration polarization. This is known to occur close to micro-/nano-interfaces provided that the sizes of the nanopores are not too large compared to the Debye screening length. However, operation of the corresponding EO pumps can be quite sensitive to the solution concentration and, thus, unstable in practical applications. Concentration polarization of ion-exchange membranes is much more robust. However, the hydraulic permeability of the membrane is very low, which makes EO flows through them extremely small. This communication shows theoretically how this problem can be resolved via making scarce microscopic perforations in an ion-exchange membrane and putting it in series with an EO-active nano-porous medium. The problem of coupled flow, concentration and electrostatic-potential distributions is solved numerically by using finite-element methods. This analysis reveals that even quite scarce perforations of micron-scale diameters are sufficient to observe practically-interesting EO flows in the system. If the average distance between the perforations is smaller than the thickness of the EO-active layer, there is an effective homogenization of the electrolyte concentration and hydrostatic pressure in the lateral direction at some distance from the interface. The simulations show this distance to be somewhat lower than the half-distance between the perforations. On the other hand, when the surface fraction of perforations is sufficiently small (below a fraction of a percent) this “homogeneous” concentration is considerably reduced (or increased, depending on the current direction), which makes the EO strongly non-linear and asymmetric. This analysis provides initial guidance for the design of high-productivity and inexpensive AC electroosmotic pumps.

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

Environmental Chemistry ◽

10.1071/en18202 ◽

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.

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