Strontium adsorption

Adsorption of Strontium in Equilibrium-Type and Column Experiments. Laboratory batch equilibrium experiments were used as a rapid method for selecting ion exchangers for testing in columns. Distribution coefficients were obtained for strontium adsorption by equilibrating 1 g of resin or zeolite in 100 ml of basin water and agitating for 24 hr at ambient temperature. After centrifuging, the concenti ation of strontium-90 in the supernate was determined. Table VI shows the measured dis-... 

Strontium adsorption onto soil minerals is an important retardation mechanism for Sr " ". Chen et al. (1998) investigated the adsorption of Sr " " onto kaolinite, illite, hectorite, and montmorillonite over a range of ionic strengths and from two different electrolyte solutions, NaNO3 and CaCb- In all cases, the EXAFS spectra suggested Sr adsorbed to clay minerals as an outer-sphere mononuclear complex. Sahai et al. (2000) also found that on amorphous silica, goethite, and kaolinite substrates, Sr"+ adsorbed as a hydrated surface complex above pH 8.6. On the other hand, Collins et al. (1998) concluded from EXAFS spectra that Sr " " adsorbed as an inner-sphere complex on goethite. 

Organic conq>lexation of Si is not e q)ected to contribute to the mobility of Sr in the Hanford subsurfece, as evidenced by kinetic and repacked column e q)eriments in which SrEDTA was rapidly dissociated in presence of Hanford sediments. Strontium adsorption was significant during transport in unsaturated, intact Hanford core in which preferential flow was minimal and... 

Robertson [ 57 ] has measured the adsorption of zinc, caesium, strontium, antimony, indium, iron, silver, copper, cobalt, rubidium, scandium, and uranium onto glass and polyethylene containers. Radioactive forms of these elements were added to samples of seawater, the samples were adjusted to the original pH of 8.0, and aliquots were poured into polyethylene bottles, Pyrex-glass bottles and polyethylene bottles contained 1 ml concentrated hydrochloric acid to bring the pH to about 1.5. Adsorption on the containers was observed for storage periods of up to 75 d with the use of a Nal(Tl) well crystal. Negligible adsorption on all containers was registered for zinc, caesium, strontium, and... 

Kinniburgh, D.G. Syers, J.K. Jackson, M.L. (1975) Specific adsorption of trace amounts of calcium and strontium by hydrous oxides of iron and aluminum. Soil Sci. Soc. Am. J. 39 464-470... 

In the column infiltration experiments with strontium, the model predictions closely resemble the experimental curves for the four flow rates compared. The input parameters to the ARDISC model were derived from experimental data obtained in infiltration experiments. The model predictions were based on the assumptions that the rate for adsorption and the rate for desorption were equal and that the sorption reactions were both first order. 

S., "Exchange Adsorption of Strontium on Clay Minerals," U. S. Geol. Surv. Bull., (1964), 1140C. 

Sorption on oxides and hydrous oxides has been extensively studied both experimentally and theoretically. In order to define an ideal oxide or hydrous oxide exchanger, we will rely on experiments with well-defined sorbents such as chromatographic alumina (1-4). Briefly, the adsorption characteristics of oxides and hydrous oxides are (1) At high pH, they act as cation exchangers but with less sensitivity to the total salt concentration than clay minerals. This behavior is illustrated in Figure 2, where sorption of strontium on alumina is shown. 

Barium reacts with metal oxides and hydroxides in soil and is subsequently adsorbed onto soil particulates (Hem 1959 Rai et al. 1984). Adsorption onto metal oxides in soils and sediments probably acts as a control over the concentration of barium in natural waters (Bodek et al. 1988). Under typical environmental conditions, barium displaces other adsorbed alkaline earth metals from MnO2, SiO2, and TiO2 (Rai et al. 1984). However, barium is displaced from Al203 by other alkaline earth metals (Rai et al. 1984). The ionic radius of the barium ion in its typical valence state (Ba+) makes isomorphous substitution possible only with strontium and generally not with the other members of the alkaline earth elements (Kirkpatrick 1978). Among the other elements that occur with barium in nature, substitution is common only with potassium but not with the smaller ions of sodium, iron, manganese, aluminum, and silicon (Kirkpatrick 1978). 

The similarity in the adsorption behavior of krypton on the three kinds of mica surfaces suggests that the adsorption here is primarily due to dispersion forces, with very little contribution from ion-induced dipole forces. The results of Barrer and Stuart (1) for the adsorption of argon on various ion-exchanged forms of faujasite are similar. They found that while calcium, strontium, and lithium faujasite—i.e., the materials containing cations with greater polarizing power—did show heat effects correlatable with ion-induced dipole interactions, no such effects were observed with sodium, potassium, or barium zeolites. With the latter materials, they also concluded that the adsorbed argon possessed appreciable mobility. 

Nemes, Z., N. M. Nagy, and J. Konya (2005). Kinetics of strontium ion adsorption on Carpathian Basin bentonite samples. J. Radisonal. Nucl. Chem. 266 289-293. 

PAN-KCoFC and PAN-4A composite adsorbents were prepared for the removal of cesium and strontium ions from acidic nuclear waste solutions. High porous spheri( composite adsorbents could be prepared using a dual nozzle technique. The acid and radiation stability tests showed that the both composite adsorbents were stable against acid solutions higher than pH - 2 and radiation dose less than 1.89 MGy, respectively. Adsorption tests showed that the PAN-KCoFC was selective for cesium ion and the PAN-zeolite 4A was for strontium ions, respectively. The ion exchange equilibrium isotherms were obtained and evaluated for the binary systems. 

Seme R. J. and Gore V. L. (1996) Strontium-90 Adsorption-Desorption Properties and Sediment Characterization at the 100 N-area. Pacific Northwest National Eaboratory. 

The replacement of sodium ions by ions of calcium and strontium leads to a decrease in the adsorption value per unit cell. A similar picture is observed in studies of adsorption of benzene vapor on calcium forms. 

The hold-hack carriers are those used to prevent adsorption on precipitates. For instance in the separation of Sr and La from fission products, precipitation of the Sr as sulphate takes place only when sufficient inert strontium... 

Non-isotopic carriers have their uses as may be judged by the following example. Sr is made from by an (n, p) reaction. The addition of a lead salt followed by fuming nitric acid precipitates lead and strontium together as nitrates and leaves the yttrium in solution. The lead, having thus acted as a non-isotopic carrier, may be precipitated as sulphide from a solution of the lead and strontium salts. Here again a hold-back carrier of inactive strontium ions is necessary to prevent adsorption of most of the Sr on the PbS. 

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