A natural ion exchange medium for radioactive59Fe fallout abatement (original) (raw)
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.
Journal of Radioanalytical and Nuclear Chemistry, 1995
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.
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.
Removal of Mn(II), Fe(III) and Cr(III) from aqueous solutions using Bulgarian clinoptilolite
Bulgarian Chemical Communications
The main purpose of the present work was to study the adsorption of Mn(II), Fe(III) and Cr(III) from aqueous solutions onto natural and pretreated Bulgarian clinoptilolite from Beli plast deposit. Batch adsorption studies were carried out to evaluate the effect of contact time, temperature, solution pH and initial concentration of investigated ions. The equilibrium adsorption data were fitted to linear Langmuir, Freundlich and Dubinin-Radushkevich models and maximum adsorption capacities were calculated. The adsorption of the investigated ions followed pseudo-second-order reaction kinetics, as well as a Freundlich isotherm. The results clearly showed that the treatment with NaCl improved the adsorption capacity of natural clinoptilolite. It was found that the removal of all investigated ions from a multicomponent aqueous solution was significantly affected by the presence of competing ions.
Radiochimica Acta, 2008
Various types of liquid radioactive wastes are released from different nuclear activities. The treatment efficiencies of these wastes depend highly on the physical and chemical composition of each waste such as pH, TDS and electrical conductivity. The treatment efficiency of some radionuclides with different valency states (such as 134Cs, 65Zn, 60Co and 152+154Eu) was tested based on the absorption capacity of cationic exchanger (KY-2) functionlized with polystyrene sulphonic group. The competitive adsorption on cationic exchanger was investigated by mono radionuclide and multi radionuclides wastes. The influence of the presence of various anionic complexants in the rad-waste on the adsorption capacity and hence the treatment efficiency was quantitatively studied using weakly base aminated anionic exchanger (AN-31). The enhancement in decontamination factor of each radionuclide is mostly attributed to the high adsorption capacity of the cationic resin in addition to the complexation...
Adsorption–desorption of heavy metal ions
Adsorption and desorption studies on different types of adsorbents, including natural materials such as teak tree bark powder, rice husk, natural bentonite, different algae like Ecklonia maxima, Escherichia coli, Ascophyllum nodasum, Rhizopus nigricans, Cladophora fascicularis, goethite and soils of three nuclear power plant and artificial materials such as Fe oxide-coated sand, goethite pretreated with phosphate, dithizone-modified sodium trititanate whisker, modified nano-metre sized TiO 2 , Chromosorb 102 resins and poly(m-phenylenediamine) are summarized. The kinet-ics, thermodynamics, sorption/desorption mechanism of different metal ions on different adsorbents under different experimental conditions are discussed. It is found that desorbing agent is greatly dependent on the adsorbate used. All the metal ions are desorbed using acids like HCl, HNO 3 and H 2 SO 4 in most of the cases, except Cr(VI). EDTA can be used to remove Pb 2+ and Zn 2+ in addition to acids. Since Cr(VI) is present in anionic form; it can be eliminated from the loaded adsorbents using bases like NaOH, Na 2 CO 3 or NaHCO 3 .