Self-diffusion of trace concentrations of 144Ce, 147Pm and 155Eu in water solutions

Kepák, F.; Křivá, J.

doi:10.1016/0022-1902(71)80611-5

Cited by 18 publications

(2 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Very little sedimentation in the centrifugal field applied takes place at pH 2 and lower, whereas a substantial part of cerium undergoes the sedimentation at pH > 3, particularly from the aged solutions. This finding indicates an existence of colloidal or larger particles of carrier-free cerium in the studied solutions and agrees qualitatively with the data obtained previously by centrifugation [11,15], ultrafiltration [10,11] and diffusion [13]. From the conditions of centrifugation it is possible to estimate the lowest diameter of particles completely centrifuged out in our experiments.…”

Section: Resultssupporting

confidence: 93%

“…The diffusion coefficients found at higher pH values can not be considered as real diffusion coefficients since two or more forms of cerium are present in the solution and the diffusion coefficient obtained under such conditions does not represent a mean diffusion coefficient [28]. The decrease in the apparent diffusion coefficient at pH 3 -5, which is similar to the decrease observed by KEPÄK and KfclVA [13], reflects the formation of cerium pseudocolloids. In separate experiments with carrier-free 144 Ce we found that an addition of indifferent electrolyte (NaCl) to the studied solution enhances the apparent diffusion coefficient of cerium [28].…”

Section: Resultsmentioning

confidence: 53%

See 1 more Smart Citation

Radiochemical Study of the Physicochemical State of Trace Cerium in Aqueous Solutions

1979

View full text Add to dashboard Cite

The physicochemical state of trace cerium (III) in aqueous chloride solutions was studied using centrifugation, free-liquid electrophoresis and continuous capillary diffusion methods and 141 Ce. It has been found that cerium is present predominantly as Ce 3 + cations in 0.1 -0.001 Μ solutions of hydrochloric acid. Colloidal forms of carrier-free 141 Ce exist in the solutions of lower acidity (pH > 3). They are formed by adsorption of cerium ions'on colloidal impurities in the solutions or by coprecipitation of cerium with colloidal ferric hydroxide, present in the solutions as an impurity. Tervalent cerium does not undergo a hydrolysis at pH < 5.Knowledge of the physicochemical state of trace elements in aqueous solutions is of considerable importance for prediction and interpretation of behaviour of trace elements in many physicochemical and biochemical processes [1,2]. The physicochemical state of trace cerium in aqueous solutions is not sufficiently known. Particularly the hydrolysis and the colloidal behaviour of tervalent cerium are subject to controversies among various authors. Thus for instance STEPANOV and SHVEDOV [3], SHALINEC [4] and PUSTOVALOV et al. [5] claim that hydrolysis of trace cerium is significant already at pH > 2-3, whereas it should be negligible (less than 10%) at pH < 8 according to the hydrolytic constants published by other authors [6,7], Formation of colloidal forms of trace cerium(III) in aqueous solutions has been reported by several authors [8 -16]. However, the authors largely disagree as to the nature and the region of existence of the colloids. This is mainly due to different conditions and methods used for the studies and sometimes also due to inadequate interpretation of the data obtained. It seemed therefore useful to reinvestigate these problems using well defined conditions and combining several methods of study. Electrophoresis, centrifugation and capillary diffusion were used to elucidate the physicochemical state of trace cerium in aqueous solutions labelled with carrier-free 141 Ce. Experimental Reagents and solution preparationTriply distilled water and p. a. reagents were used throughout. All stock solutions were prepared by dissolving or diluting exact amounts of chemicals and were stored in clean polyethylene bottles. Stock solutions of sodium hydroxide were prepared from carbonate-free, 50% solution of NaOH. Preparations of 141 Ce (carrier-free, CeCl 3 in 1 Μ HCl), supplied by Zentralinstitut für Kernforschung, Rossendorf near Dresden, were used as radiotracers. They were suitably diluted with 0.01 Μ HCl. For some experiments, a standard inactive solution of CeCl 3 was added.The experimental solutions were prepared by gradually mixing the stock solutions of radiocerium, 0.01 Μ HCl and 0.01 Μ or 0.1 Μ NaOH so as to obtain the desired pH. All the mixing was carried out at room temperature in a glove box to avoid an uncontrolled contamination of the solutions with dust. Unless stated otherwise, the ionic strength of the solutions was 0.01 (HCl + NaCl + NaOH). The solu...

show abstract

Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 53%

Radiochemical Study of the Physicochemical State of Trace Cerium in Aqueous Solutions

1979

View full text Add to dashboard Cite

show abstract

The low gas flow rate foam separation of cerium (III) from dilute aqueous solutions

Shakir¹,

Aziz²

1977

J. Biochem. Toxicol.

View full text Add to dashboard Cite

Two low gas flow rate foam separation techniques, ion and precipitate flotation, have been investigated for the separation of trivalent cerium from solutions with initial cerium concentrations ranging from 1 x lo-@ to 1 x 1 0 -4~ in the pH range of 1.8-12 using the anionic collector sodium lauryl sulphate and the cationic surfactant cetyl trimethyl ammonium bromide. In addition to the type of collector, the pH and the cerium ion concentration, and other factors which can affect flotation results, viz. the time period of bubbling, the rate of gas flow, the ageing of both the cerium and the collector ions, the ionic strength, and the concentration of the collector ions have been investigated and optimum conditions have been established. Under optimum conditions removals as high as 98.5 % can be achieved.

show abstract

The low gas flow rate foam separation of cerium (III) from dilute aqueous solutions

Shakir

Aziz

1977

J. Appl. Chem.

View full text Add to dashboard Cite

Two low gas flow rate foam separation techniques, ion and precipitate flotation, have been investigated for the separation of trivalent cerium from solutions with initial cerium concentrations ranging from 1 × 10−8 to 1 × 10−4M in the pH range of 1.8–12 using the anionic collector sodium lauryl sulphate and the cationic surfactant cetyl trimethyl ammonium bromide. In addition to the type of collector, the pH and the cerium ion concentration, and other factors which can affect flotation results, viz. the time period of bubbling, the rate of gas flow, the ageing of both the cerium and the collector ions, the ionic strength, and the concentration of the collector ions have been investigated and optimum conditions have been established. Under optimum conditions removals as high as 98.5% can be achieved.

show abstract

Self-diffusion of trace concentrations of 144Ce, 147Pm and 155Eu in water solutions

Cited by 18 publications

References 7 publications

Radiochemical Study of the Physicochemical State of Trace Cerium in Aqueous Solutions

Radiochemical Study of the Physicochemical State of Trace Cerium in Aqueous Solutions

The low gas flow rate foam separation of cerium (III) from dilute aqueous solutions

The low gas flow rate foam separation of cerium (III) from dilute aqueous solutions

Contact Info

Product

Resources

About