The chemistry of cadmium in natural water—I a study of cadmium complex formation using the cadmium specific-ion electrode

Gardiner, James L.

doi:10.1016/0043-1354(74)90005-0

Cited by 135 publications

(44 citation statements)

References 6 publications

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“…Of these, only seven report data for homogeneous equilibria, and only five investigations have produced useful stability constants. Two of these investigations were performed at 25 °C [76BHa,92NEa], two at 20 °C [74GAa,84STE], and one at an unspecified temperature [91RFa]. There are therefore insufficient data to justify preparation of a table in Appendix A2, or for SIT analyses.…”

Section: Thementioning

confidence: 99%

“…Using ise potentiometry [74GAa] studied the formation of CdCO 3 (aq), reaction 14, at 20 °C. Although results were obtained at several concentrations of NaHCO 3 [2.5, 5.0, and 10 mmol kg -1 ] as the supporting electrolyte, due to the paucity of data at the lower concentrations only that obtained at the highest bicarbonate concentration (log 10 K 1 = 4.02 ± 0.04 at I m = 0.01 mol kg -1 ) appears to be reliable.…”

Section: Formation Of Cdco 3 (Aq)mentioning

confidence: 99%

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Chemical speciation of environmentally significant metals with inorganic ligands. Part 4: The Cd2+ + OH–, Cl–, CO32–, SO42–, and PO43– systems (IUPAC Technical Report)

Powell

Brown

Byrne

et al. 2011

Pure and Applied Chemistry

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Abstract:The numerical modeling of Cd II speciation amongst the environmental inorganic ligands Cl -, OH -, CO 3 2-, SO 4 2-, and PO 4 3-requires reliable values for the relevant stability (formation) constants. This paper compiles and provides a critical review of these constants and related thermodynamic data. It recommends values of log 10 β p,q,r°v alid at I m = 0 mol kg -1 and 25 °C (298.15 K), along with the equations and empirical reaction ion interaction coefficients, Δε , required to calculate log 10 β p,q,r values at higher ionic strengths using the Brønsted-Guggenheim-Scatchard specific ion interaction theory (SIT). Values for the corresponding reaction enthalpies, Δ r H, are reported where available. Unfortunately, with the exception of the Cd II -chlorido system and (at low ionic strengths) the Cd II -sulfato system, the equilibrium reactions for the title systems are relatively poorly characterized.In weakly acidic fresh water systems (-log 10 {[H + ]/c°} < 6), in the absence of organic ligands (e.g., humic substances), Cd II speciation is dominated by Cd 2+ (aq), with CdSO 4 (aq) as a minor species. In this respect, Cd II is similar to Cu II [2007PBa] and Pb II [2009PBa]. However, in weakly alkaline fresh water solutions, 7.5 < -log 10 {[H + ]/c°} < 8.6, the speciation of Cd II is still dominated by Cd 2+ (aq), whereas for Cu II [2007PBa] and Pb II [2009PBa] the carbonato-species MCO 3 (aq) dominates. In weakly acidic saline systems (-log 10 {[H + ]/c°} < 6; -log 10 {[Cl -]/c°} < 2.0) the speciation is dominated by CdCl n (2-n)+ complexes, (n = 1-3), with Cd 2+ (aq) as a minor species. This is qualitatively similar to the situation for Cu II and Pb II . However, in weakly alkaline saline solutions, including seawater, the chlorido-complexes still dominate the speciation of Cd II because of the relatively low stability of CdCO 3 (aq). In contrast, the speciation of Cu II [2007PBa] and Pb II [2009PBa] in seawater is dominated by the respective species MCO 3 (aq). There is scope for additional high-quality measurements in the Cd 2+ + H + + CO 3 2-system as the large uncertainties in the stability constants for the Cd 2+ -carbonato complexes significantly affect the speciation calculations.

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Section: Thementioning

confidence: 99%

Section: Formation Of Cdco 3 (Aq)mentioning

confidence: 99%

Chemical speciation of environmentally significant metals with inorganic ligands. Part 4: The Cd2+ + OH–, Cl–, CO32–, SO42–, and PO43– systems (IUPAC Technical Report)

Powell

Brown

Byrne

et al. 2011

Pure and Applied Chemistry

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“…There are several techniques for investigating the metal ion distribution in solution: anodic stripping voltammetry (ASV) (15)(16)(17), ion selective electrodes (18,19), and dialysis or ultrafiltration (20,21). Guy and Chakrabarti (22) have compared ASV and size separation procedures and concluded that, since the adsorption of organic substances onto the hanging mercury drop electrode makes the interpretation of stripping voltammograms difficult, the size separation procedures were more convenient.…”

Section: Introductionmentioning

confidence: 99%

Studies of metal–organic interactions in model systems pertaining to natural waters

Guy¹,

Chakrabarti²

1976

Can. J. Chem.

153

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Zn(I1) with humic and tannic acids were studied to evaluate the possibility of metal speciation using a combination of dialysis/atomic absorption spectroscopy, and the p H characteristics of the metal-organic species. The stability constants of metal-organic complexes were found to decrease in the order Pb(I1) > Cu(I1) > Cd(I1) > Zn(I1) and EDTA > humic acid > tannic acid. Scatchard plots for the metal -humic acid systems indicated two types of binding sites with a difference in stability constants of about 10. Ultrafiltration of metal -humic acid solutions indicated that the metal ions were concentrated in the large molecular size fractions ( > 3.1 nm). Separation by dialysis was used to investigate the release of metal from model sediment components by the organic acids (the metalorganic complexes were non-dialyzable). For release of copper from bentonite, it was found that the amount of copper released depended on both the concentration of ligand and the stability constant of metal complex, with the ratio of metal release to complexing sites decreasing in the order EDTA > humic acid > tannic acid. Release of metal from the solids decreased in the order: bentonite > Mn02 > humic acid. Release of metal from the hydrous oxides via a redox decomposition of the oxide by natural organics was investigated using pyrogallol, gallic, and tannic acids. At natural water p H levels (6-8), 20pg/ml solutions of the organic acids released 20 pmol manganese per 100 ml solutions whereas at p H 2, 60 pmol manganese were released. The pH behaviour of the organic acids has been explained in terms of formation of oxalic acid at p H < 5, which then reduces the hydrous oxide. Chem. 54, 2600Chem. 54, (1976. Faisant appel a une combinaison de spectroxopie atomique, de dialyse ainsi qu'aux caract6 ristiques de p H des esp6es organometalliques, on a 6tudie les interactions de Cu(II), de Pb(II), de Cd(I1) et de Zn(I1) avec les acides humique et tannique dans le but d'kvaluer la possibilitk de spkiation des metaux. On a trouvC que les constantes de stabilitk des complexes organom6talliques dkroissent dans I'ordre Pb(1I) > Cu(1l) > Cd(I1) > Zn(l1) et EDTA > acide humique > acide tannique. Les courbes de Scatchard pour les systtmes acide humique/metal indiquent qu'il y a deux types de sites de couplage et que la difference entre leurs constantes de stabilitk est d'environ 10. L'ultrafiltration de solutions de mCtal/acide humique indique que les ions metalliques sont concentres dans les fractions de grands poids molkulaires ( > 3.1 nm). On a utilisC la separation par dialyse pour examiner la liberation, par les acides organiques (les complexes organometalliques ne sont pas dialysables), des metaux attaches a des composants modkles de suiments. Pour la liberation du cuivre de la bentonite, on a trouvC que la quantitk de cuivre libere depend la fois de la concentration des ligands et de la constante de stabilite du complexe mCtallique avec un rapport de liberation du metal par rapport aux sites complexants qui diminue dans I'ordre EDTA > aci...

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“…Casamino-acids, not used in our medium, were the most active binding substances. In fresh water, the free cadmium ion CdZf is the dominant Cd form (Gardiner 1974, Bryan 1984, whereas at 20 and 30 YW (as in our experiments) Cd is almost completely complexed and present in the form of chloride complexes (Sunda et al 1978). As Cd toxicity is a function of free Cd ion concentration (Sunda et al 1978, Bryan 1984, the low Cd toxicity to the species we studied, especially in comparison with freshwater species, is comprehensible.…”

Section: Sensitivity To Heavy Metalsmentioning

confidence: 74%

Toxicity of cadmium to free-living marine and brackish water nematodes (Monhystera microphthalma, Monhystera dis-juncta, Pellioditis marina)

Vranken¹,

Vanderhaeghen²,

Heip³

1985

Dis. Aquat. Org.

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Cadmium toxicity to 3 marine and brackish-water nematodes (Monhystera microphthalma, M. disjuncta, Pellioditis marina) was estimated under static tests. These nematodes are very resistant to cadmium poisoning. LC 50 values are extremely time-dependent; an exposure time of 96 h underestimates the degree of toxicity. For M. rnicrophthalrna LC 50 values decreased from 23.6 ppm after 96 h to 5.4 ppm after 312 h. For M. disjuncta LC 50 values were 21.2 and 18.4 ppm after 192 and 264 h respectively. P. marina was much more tolerant to cadmium in comparison with the monhysterids and had LC 50 values of 90.5 ppm at 120, and of 77.0 ppm at 192 h. It is argued that MEC (minimum effective concentrations) values are ecologically more meaningful than LC 50 values, and that the former levels can be used as indicators of intolerable thresholds in the field. MEC values based on mortality and on a developmental assay in which success in attaining the adult stage was studied, turned out to be very similar. The developmental assay takes less time than the survival assays and the slope of the response curve can be used as a parameter for describing species sensitivity.

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The chemistry of cadmium in natural water—I a study of cadmium complex formation using the cadmium specific-ion electrode

Cited by 135 publications

References 6 publications

Chemical speciation of environmentally significant metals with inorganic ligands. Part 4: The Cd2+ + OH–, Cl–, CO32–, SO42–, and PO43– systems (IUPAC Technical Report)

Chemical speciation of environmentally significant metals with inorganic ligands. Part 4: The Cd2+ + OH–, Cl–, CO32–, SO42–, and PO43– systems (IUPAC Technical Report)

Studies of metal–organic interactions in model systems pertaining to natural waters

Toxicity of cadmium to free-living marine and brackish water nematodes (Monhystera microphthalma, Monhystera dis-juncta, Pellioditis marina)

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