Sorption mechanism of trace amounts of divalent metal ions on a chelating resin containing iminodiacetate groups

Pesavento, Maria; Biesuz, Raffaela; Gallorini, M.; Profumo, Antonella

doi:10.1021/ac00066a021

Cited by 120 publications

(95 citation statements)

References 9 publications

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“…3,7 The intrinsic protonation constants, which refer to the activity of proton in a resin phase, were as follows: log K1 = 9.12, log K2 = 3.10, log K3 = 1.44. The observed protonation constants, which refer to the activity of proton in an aqueous phase, on the other hand, depended on the ionic strength (I); e.g., (log K2, I/mol kg -1 ): (4.5, 0.013), (3.9, 0.1), (3.1, 1.0).…”

Section: Resultsmentioning

confidence: 99%

“…Adsorption experiments were carried out under two different conditions. One condition was a total amount of metal ions in excess against that of IDA, TAM > TAL; a 50 cm 3 -portion of 10 -3 mol dm -3 solution (0.05 mmol metal) was added to 0.0125 g of the resin (0.025 mmol IDA). The other condition was a total amount of IDA in excess against that of metal ions, TAL > TAM; a 50 cm 3 -portion of 10 -4 mol dm -3 solution (0.005 mmol metal) was added to 0.2 g of the resin (0.4 mmol IDA).…”

Section: Methodsmentioning

confidence: 99%

“…2 Recently, based on a Gibbs-Donnan model, the adsorption equilibria of divalent metal ions (M 2+ ) to IDA-type resins have been studied intensively. 3 A competition method with protonation was adopted under the condition of the total amount of functional groups in excess against that of metal ions (TAL > TAM). The deviation of the observed adsorption capacities from those calculated using the adsorption constants of [(-L)M II ] was assigned to the adsorption as [(-LH)2M II ], for which the adsorption constants were evaluated; the adsorption constants of [(-L)M II ] were assumed to be the same as the stability constants of metal complexes with methyliminodiacetate in an aqueous solution.…”

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Direct Evidence for Two Interaction Modes in Adsorption of Divalent Metal Ions to Iminodiacetate-Type Chelating Resins

et al. 2002

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Adsorption to chelating resins is efficient for separation and concentration of metal ions prior to their determination. 1 Iminodiacetate(IDA)-type chelating resins (-L 2-) are commercially available and widely used. It is also well known that the adsorption curves of Co 2+ , Zn 2+ , and especially Mn 2+ , Cd 2+ , and Pb 2+ are shifted to a higher pH region in the application to seawater, compared with freshwater. 2 Recently, based on a Gibbs-Donnan model, the adsorption equilibria of divalent metal ions (M 2+ ) to IDA-type resins have been studied intensively. 3 A competition method with protonation was adopted under the condition of the total amount of functional groups in excess against that of metal ions (TAL > TAM). The deviation of the observed adsorption capacities from those calculated using the adsorption constants of [(-L)M II ] was assigned to the adsorption as [(-LH)2M II ], for which the adsorption constants were evaluated; the adsorption constants of [(-L)M II ] were assumed to be the same as the stability constants of metal complexes with methyliminodiacetate in an aqueous solution. The effects of salts on the adsorption have also been described quantitatively, but the presentation is rather complicated. 4 In contrast, we have proposed a competition method with protonation under a reversed condition of the total amount of metal ions in excess against that of functional groups (TAM > TAL), and have applied it to analyses of the adsorption equilibria of trivalent and tetravalent metal ions to an IDA-type chelating resin; the presence of [(-LH)3M III ] (M III : Sc, Y, La) and [(-LH)4Th IV ] was reflected in the adsorption curves. 5,6 In this study, we applied this type of analysis to the adsorption of divalent metal ions to directly demonstrate the presence of [(-LH)2M II ] as well as [(-L)M II ] and also give a rather qualitative, but intuitive, explanation for the effects of salts on the adsorption equilibria. ExperimentalStock solutions of metal ions were prepared from reagent-grade nitrates. The IDA-resin used was Amberlite IRC-718 (Rohm and Haas; particle size of 0.40 -0.56 mm, Na-form, IDA density of 2.0 mmol g -1 ). Adsorption experiments were carried out under two different conditions. One condition was a total amount of metal ions in excess against that of IDA, TAM > TAL; a 50 cm 3 -portion of 10 -3 mol dm -3 solution (0.05 mmol metal) was added to 0.0125 g of the resin (0.025 mmol IDA). The other condition was a total amount of IDA in excess against that of metal ions, TAL > TAM; a 50 cm 3 -portion of 10 -4 mol dm -3 solution (0.005 mmol metal) was added to 0.2 g of the resin (0.4 mmol IDA). The pH values were adjusted by addition of an acid or a base, and were measured on an activity scale using standard buffer solutions. After adjustment of the ionic strength with NaCl and of the total volume, the resulting solutions were shaken with an IDA-resin for two days at 25˚C. Equilibration required longer time for TAM > TAL than for TAL > TAM. The supernatants were subjected to the pH measuremen...

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Direct Evidence for Two Interaction Modes in Adsorption of Divalent Metal Ions to Iminodiacetate-Type Chelating Resins

et al. 2002

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“…The resins were washed according to the procedure previously described. 15 This treatment is required to eliminate trace level metal ions that may be present in the resins. The resins were finally converted into the NH4 + form by treatment with 1 M high purity ammonia.…”

Section: Reagentsmentioning

confidence: 99%

“…A portable pH-meter (Model 290A, Orion) and a MettlerToledo (InLab 412) combined glass electrode were used for the pH determinations on board; the electrode was standardized in H + concentration as previously reported 15 and used for pH measurements after filtration and on the different aliquots after RT equilibration.…”

Section: Apparatusmentioning

confidence: 99%

Determination of the Total Concentration and Speciation of Metal Ions in River, Estuarine and Seawater Samples

2008

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Different natural water samples were investigated to determine the total concentration and the distribution of species for Cu(II), Pb(II), Al(III) and U(VI). The proposed method, named resin titration (RT), was developed in our laboratory to investigate the distribution of species for metal ions in complex matrices. It is a competition method, in which a complexing resin competes with natural ligands present in the sample to combine with the metal ions. In the present paper, river, estuarine and seawater samples, collected during a cruise in Adriatic Sea, were investigated. For each sample, two RTs were performed, using different complexing resins: the iminodiacetic Chelex 100 and the carboxylic Amberlite CG50. In this way, it was possible to detect different class of ligands. Satisfactory results have been obtained and are commented on critically. They were summarized by principal component analysis (PCA) and the correlations with physicochemical parameters allowed one to follow the evolution of the metals along the considered transect. It should be pointed out that, according to our findings, the ligands responsible for metal ions complexation are not the major components of the water system, since they form considerably weaker complexes.

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Acidity, Basicity and Complex Formation

Klapötke

2009

Patai's Chemistry of Functional Groups

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Sorption mechanism of trace amounts of divalent metal ions on a chelating resin containing iminodiacetate groups

Cited by 120 publications

References 9 publications

Direct Evidence for Two Interaction Modes in Adsorption of Divalent Metal Ions to Iminodiacetate-Type Chelating Resins

Direct Evidence for Two Interaction Modes in Adsorption of Divalent Metal Ions to Iminodiacetate-Type Chelating Resins

Determination of the Total Concentration and Speciation of Metal Ions in River, Estuarine and Seawater Samples

Acidity, Basicity and Complex Formation

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