A natural ion exchange medium for radioactive59Fe fallout abatement (original) (raw)
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Evaluation of Natural Ion Exchangers for the Removal of Radioactive Isotopes from Liquid Effluents
Environmental Engineering and Management Journal, 2002
This paper shows results of tests in which clinoptilolite powders were evaluated for treating the radioactive wastes streams. The objective of this study was to examine the ion-exchange characteristics and the abilities to uptake radioisotopes of indigene clinoptilolite from Marsid area-Romania. The effect of particle size and contacting time on K d and radioactivity removal was studied.
Applied Radiation and Isotopes, 1999
Five samples of natural zeolites from different parts of Iran were chosen for this study. In order to characterize and determine their structures, X-ray diffraction and infrared spectrometry were carried out for each sample. The selective absorption properties of each zeolite were found by calculating the distribution coefficient (K d) of various simulated wastes which were prepared by spiking the radionuclides with 131 I, 99 Mo, 153 Sm, 140 La and 147 Nd. All the zeolite samples used in this study had extremely high absorption value towards 140 La; clinoptolite from Mianeh and analsite from Ghalehkhargoshi showed good absorption for 147 Nd; clinoptolite from Semnan and clinoptolite from Firozkoh showed high absorption for 153 Sm; mesolite from Arababad Tabas showed good absorption for 99 Mo; and finally mesolite from Arababad Tabas, clinoptolite from Semnan and clinoptolite from Firozkoh could be used to selectively absorb 131 I from the stimulated waste which was prepared. The natural zeolites chosen for these studies show a similar pattern to those synthetic ion exchangers in the literature and in some cases an extremely high selectivity towards certain radioactive elements. Hence the binary separation of radioactive elements could easily be carried out. Furthermore, these zeolites, which are naturally occurring ion exchangers, are viable economically and extremely useful alternatives in this industry.
Applied Geochemistry
The application of a multi-site ion-exchange (MSIE) model to the prediction of contaminant behaviour onto soils or sediments requires a coherent adsorption database. Following the same approach exposed in preceding works on smectite (Siroux et al., Appl. Geochem. 87, 167; Wissocq et al., Appl. Geochem., 93, 167), a database is here implemented to allow modelling the adsorption of radionuclides 90 Sr and 137 Cs onto Naillite, one of the major clay mineral encountered in the terrestrial environment. This database allows describing the adsorption properties of Sr 2+ and Cs + competing with major cations H +-considered as the reference cation-and Na + onto an Na-illite. To obtain the adsorption site capacities and selectivity coefficients of illite sites for Na + towards H + , a saturation curve of Na + on Na-conditioned illite was acquired. Adsorption isotherms issued from literature have been reinterpreted using the MSIE model to obtain the adsorption properties of Sr 2+ and Cs + onto purified and Na-conditioned illite. Afterwards, the predictability and robustness of the database were verified simulating experimental adsorption of Sr 2+ and Cs + onto Na-illite/Na-smectite mixtures.
Adsorption of As(III) Ions onto Iron-containing Waste Sludge
Adsorption Science & Technology, 2010
The adsorption performance of a low-cost adsorbent (IS), viz. an iron-containing waste sludge arising during a hot-dip galvanizing process, towards the removal of As(III) ions from synthetic aqueous solutions and natural underground water was examined. The adsorption process was best described by the pseudo-second-order kinetic equation. The equilibrium adsorption data were well described by the Langmuir model. The value of the dimensional separation factor, R L , indicated favourable adsorption. The maximum adsorption capacity of IS was 625 µg As(III)/g. The variation in the extent of adsorption with temperature was used to evaluate the thermodynamic parameters for the adsorption process. The values of ∆H 0 and ∆G 0 obtained demonstrated that the adsorption process was exothermic and spontaneous. The studied material exhibited an excellent As(III) ion adsorption performance from both synthetic solutions and a natural water sample. Moreover, no secondary contaminated substances arise if the exhausted adsorbent is recycled (e.g. in glass applications).
Affinity and removal of radionuclides mixture from low-level liquid waste by synthetic ferrierites
Journal of Radioanalytical and Nuclear Chemistry, 2011
The affinity and removal efficiency of 137 Cs ? , 133 Ba 2? , 85 Sr 2? and 241 Am 3? mixture from aqueous solutions using two synthetic ferrierites HSZ 700KOA and 700KOD commercially used as a catalyst in oil industry were investigated. The uptake of metal ions as a function of different parameters has been studied using batch equilibrium technique. Kinetic curves showed that the equilibrium was mostly reached within 45 min for Cs ? and Ba 2? and revealed to be longer for Sr 2? and Am 3?. Using Freundlich and Langmuir adsorption isotherms, the results showed that the affinity and adsorption capacity of 700KOA and 700KOD follow the order: Cs ? [ Ba 2? [ Sr 2? [ Am 3? with higher values for first material. Both adsorbents exhibited significant high capacity for Cs ? relative to other cations giving q max 1.97 and 1.78 mmol g-1 for 700KOA and 700KOD, respectively. All metals uptake found to be concentration dependant and independent of the pH over 2 to 10 range except Am 3? ; this reveals that the adsorption mechanism is controlled mainly by pure ion exchange reaction for Cs ? , Ba 2? , Sr 2? and by surface complexation mechanism for Am 3?. These simple nontoxic materials are recommended to be used for radioactive waste treatment especially fission product 137 Cs and activation product 133 Ba.
Ion exchangers in radioactive waste management: Natural Iranian zeolites
Applied Radiation and Isotopes, 2006
The adsorption behaviour of Ba(lI) on titanium(IV) oxide in an aqueous solution was studied by means of batch technique as a function of Ba(ll) concentration, temperature and solution pH using Ba-140 as radiotracer. The results show that adsorption is essentially complete in ca 2 h and that the steady state values of adsorption at various concentrations agree well with the classical Freundlich isotherm and follow first order kinetics. The pH and temperature of the solution markedly affect the extent of adsorption. The nature and mechanism of adsorption are discussed.
Separation and Purification Technology, 2002
Distribution coefficients of cesium on natural and cation-enriched (Na + , K + , NH 4 + and Ca + 2 ) forms of clinoptilolite were measured by batch, radioactive tracer technique. The measurements were carried out for an initial cesium concentration range of 10 − 6 -10 − 1 mol/dm 3 and at temperatures of 25, 40, 60 and 80°C. Experimental isotherms evaluated from distribution coefficients were fit to Langmuir, Freundlich and Dubinin-Radushkevich (D-R)models. Of the models tested, D-R model was found to represent the isotherms better in a wider range of concentrations than either Langmuir or Freundlich model. Breakthrough behavior of cesium on natural and cation-enriched forms of clinoptilolite for a particular set of conditions were also determined in a small size column. Column parameters were evaluated using mass transfer zone concept.
Removal of some radioactive nuclides by in-situ precipitation with ion exchange materials
Czechoslovak journal of …, 1999
In-situ precipitation of some radwaste elements with cerium(IV)-and tin(IV) antimonates (134Cs, 60Co, 85Sr and 152, 154Eu ) together with 10 -4 M of each Cs +, Co 2 § Sr 2+ and/or Eu 3+ have been prepared and found that all the product precipitates prefer the ions of smaller ionic radii. The distribution coefficients of Cs § Co 2 § Sr 2 § and Eu 3 § for all products were determined and it was found that the separation factors between neighbouring pairs of metal ions are larger on tin(IV) antimonate (SnSb) than cerium(IV) antimonate (CeSb). The adsorption of Cs § Co 2 § Sr 2 § on CeSb and SnSb column beds was investigated and the preliminary results given here demonstrate the promise of potential applicability of these materials in many separations connected with nuclear fuel cycle activities.
Journal of Ecological Engineering, 2018
The paper presents the investigation on the estimated efficiency of iron (III) chloride solutions in the decontamination process of radioactive soils with 90 Sr, according to kinetic and thermodynamic characteristics of the desorption process. The specific 90 Sr radioactivity of soil samples was (3.9±0.3)•10 4 Bq•g. The adsorption isotherms of Sr 2+ and Fe 3+ are described with the Langmuir equation. The values of Gibbs energy G 0 298 =-4.65 kJ•mol-1 and equilibrium ion exchange constant K eq = 6.5 confirm the hypothesis of strontium removal from soils with iron (III) cations. The effectiveness of the method is substantiated by experimental and calculated results of this study samples of radioactive soils are deactivated in 90% after 9.5 hours, whereas the kinetic constant is 6.77•10 s-1. The suggested method of soil cleanup with 0.2 M Fe 3+ solutions is optimal and complies with the environmental requirements.