Authors:R. Yavari, Y. Huang, S. Ahmadi, and G. Bagheri
This study investigates uptake of cesium and strontium from aqueous solution similar to nuclear waste on three samples of
titanium molybdophosphate (TMP) synthesized under various conditions. Effects of concentration of sodium nitrate, pH and contact
time on the uptake of cesium and strontium have been studied by bath method. The results showed that TMP has high affinity
toward cesium and strontium at pH > 2 and relatively low concentration of sodium nitrate. Kinetic data indicated that cesium
uptake process to achieve equilibrium was faster than strontium. Cesium and strontium breakthrough curves were examined at
25 °C using column packed with H3O+ form of TMP and breakthrough curves showed symmetrical S-shaped profiles. At the same time, the calculated breakthrough capacity
for cesium was higher than strontium. The results of desorption studies showed that over 99% of cesium and strontium was washed
out of column by using 4 M NH4Cl solution. This study suggests that TMP can have great potential applications for the removal of strontium and specially
cesium from nuclear waste solution.
Authors:Michal Galamboš, Jana Kufčáková, and Pavol Rajec
Bentonite is a natural clay and one of the most promising candidates for use as a buffer material in the geological disposal
systems for spent nuclear fuel and high-level nuclear waste. It is intended to isolate metal canisters with highly radioactive
waste products from the surrounding rocks because of its ability to retard the movement of radionuclides by adsorption. Slovak
Republic avails of many significant deposits of bentonites. Adsorption of Cs on five Slovak bentonites of deposits (Jelšový
potok, Kopernica, Lieskovec, Lastovce and Dolná Ves) has been studied with the use of batch technique. In the case of Dolná
Ves deposit, the mixed-layer illite–smectite has been identified as the main clay component. Natural and irradiated samples,
in two different kinds of grain size: 45 and 250 μm have been used in the experiments. The adsorptions of Cs on bentonite
under various experimental conditions, such as contact time, adsorbent and adsorbate concentrations have been studied. The
Cation Exchange Capacity values for particular deposits drop in the following order: Jelšový potok > Kopernica > Lieskovec > Lastovce > Dolná
Ves. Bentonites irradiated samples with 390 kGy have shown higher specific surface and higher values of the adsorption capacity.
Distribution coefficients have been determined for bentonite-cesium solution system as a function of contact time and adsorbate
and adsorbent concentration. The data have been interpreted in terms of Langmuir isotherm. The uptake of Cs has been rapid
and the adsorption of cesium has increased with increasing metal concentrations. The adsorption percentage has decreased with
increasing of metal concentrations. Adsorption of Cs has been suppressed by presence of Ca2+ more than Na+ cation. Sorption experiments carried out show that the most suitable materials intended for use as barriers surrounding a
canister of spent nuclear fuel are bentonites of the Jelšový potok and Kopernica deposits.
Authors:Ľ. Vrtoch, M. Pipíška, M. Horník, J. Augustín, and J. Lesný
In order to gain biosorbent that would have the ability to bind cesium ions from water solution effectively, potassium nickel
hexacyanoferrate(II) (KNiFC) was incorporated into the mushroom biomass of Agaricus bisporus. Cesium sorption by KNIFC-modified A. bisporus biosorbent was observed in batch system, using radiotracer technique using 137Cs radioisotope. Kinetic study showed that the cesium sorption was quite rapid and sorption equilibrium was attained within
1 h. Sorption kinetics of cesium was well described by pseudo-second order kinetics. Sorption equilibrium was the best described
by Freundlich isotherm and the distribution coefficient was at interval 7,662–159 cm3 g−1. Cesium sorption depended on initial pH of solution. Cesium sorption was very low at pH0 1.0–3.0. At initial pH 11.0, maximum sorption of cesium was found. Negative effect of monovalent (K+, Na+, NH4+) and divalent (Ca2+, Mg2+) cations on cesium sorption was observed. Desorption experiments showed that 0.1 M potassium chloride is the most suitable
desorption agent but the complete desorption of cesium ions from KNiFC-modifed biosorbent was not achieved.
Multiwall carbon nanotubes (MWCNTs) were modified by nitric acid solution and then used to study the adsorption of cesium
from aqueous solution using a batch technique under ambient conditions. As produced and oxidized MWCNTs were characterized
by nitrogen adsorption/desorption, Boehm’s titration method and Fourier transform infrared spectroscopy. The physical properties
of MWCNTs such as functional groups, total number of acid sites and specific surface area were greatly improved after oxidation,
and these were responsible for more sorption of cesium from aqueous solution and made them more dispersible in water. The
adsorption of cesium ions as a function of contact time, initial concentration of cesium, pH, ionic strength and oxidized MWCNT concentrations was also investigated. The results showed that cesium adsorption percentage
strongly depended on the pH value, oxidized MWCNT content and on the solution ionic strength. Kinetic data indicated that
the adsorption process achieved equilibrium within 80 min. Equilibrium data for as produced and oxidized MWCNTs was well described
by both Freundlich and Langmuir isotherms. The dominant mechanism of cesium adsorption on oxidized MWCNTs may be mainly attributed
to ion exchange. This study suggests that oxidized MWCNTs can be a promising candidate for the removal of cesium from nuclear
Authors:Dmitry S. Afanasev, Nina I. Kuznetsova, and Vladimir I. Zaikovskii
the catalysts in the epoxidation. At the moment, cesium is known as the most effective promoter for the epoxidation catalysts. Its promoting effect on the oxidation of ethylene has been attributed to the deactivation of the acidic sites on the surface
Extraction of microamounts of cesium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B−) in the presence of polypropylene glycol PPG 425 (L) has been investigated. The equilibrium data have been explained assuming
that the complex species HL+ and CsL+ (L = PPG 425) are extracted into the organic phase. The values of extraction and stability constants of the cationic complex
species in nitrobenzene saturated with water have been determined.
Authors:D. Raut, P. Mohapatra, P. Wattal, and V. Manchanda
Three different resins containing ammonium molybdophosphate (AMP), viz. PMMA (polymethylmethacrylate) resin, composite AMP
resin and ALIX (a bisphenol based resin), were evaluated for their irradiation stability. The studies included batch as well
as column studies and were carried out for cesium uptake behaviour at 3 M acidity. The resin beads were irradiated to varying
dose viz., 0 MRad, 10 MRad, 20 MRad, 50 MRad and 100 MRad. The time taken to attain equilibrium was rather long and about
2–5 h were found to be required for attaining equilibrium in batch studies. Batch Cs(I) uptake studies revealed no significant
effect on the Kd values in case of the PMMA resin while in case of the composite resin and ALIX resin, a decrease in the Kd was observed as a function of irradiation dose. The resin capacity indicated contrasting behaviour with irradiation dose
for the resins. Column runs have been carried out for the uptake of radio cesium using both unirradiated and irradiated resins
using feed solutions containing 3 MHNO3. The loading capacities of the resins were found to be proportional to their Cs loading capacities observed in batch studies.
Study revealed that the composite AMP had the maximum and PMMA has the least loading capacity. Results of these studies show
that these AMP based resins can be used for cesium separation from acidic nuclear waste.
Authors:M. Galamboš, M. Magula, M. Daňo, M. Osacký, O. Rosskopfová, and P. Rajec
Bentonites which are characterized by good rheological, mineralogical and chemical stability is considered used as sealing
barriers in multibarrier Slovak system of deep geological repository for high-level radioactive waste and spent nuclear fuel.
In Slovak Republic there are several significant deposits of bentonite, which are characterized by appropriate adsorption
properties and meet the geotechnical requirements for this type of barriers. Study of adsorption properties of bentonites
and other smectites is an essential step for developing the migration model long-lived corrosion and activation products,
and fission products of uranium. Nuclear wastes contain the most important nuclear fission products, radioisotopes 134Cs and 137Cs. The present paper investigates and compares the cesium adsorption properties of Slovak and North America bentonites composed
mainly of dioctahedral smectite montmorillonite (J, L, SAz-1 and STx-1) and trioctahedral smectites saponite (SapCa-2) and
Authors:M. Galamboš, V. Paučová, J. Kufčáková, O. Rosskopfová, P. Rajec, and R. Adamcová
The physical and chemical properties of illitic clay minerals from Slovak deposit suitable for application in engineering
barriers for high level radioactive waste repositories and spent nuclear fuels were studied. The isolation of spent nuclear
fuels and high level radioactive wastes from the outer environment in a deep repository is gained by means of a system of
multiple engineering and natural sealing barriers. Vital segments in a multiple barrier system are clay rocks, of which bentonites
represent the most suitable clay material. Cs-adsorption on fine fractions of adsorbents (bentonites from three Slovak deposits:
Jelšový potok J15, Kopernica K15, Lieskovec L15 and montmorillonite K10) has been studied with using batch of radiometric
techniques. Adsorption parameters have been determined for adsorbent-cesium solution system as a function of contact time
and adsorbate concentration. The influences of pH change, the effect of competitive cations, complex-forming organic chelating
agents on the adsorption of Cs have also been studied.
Solvent extraction of microamounts of cesium by a nitrobenzene solution of hydrogen dicarbollylcobaltate (H+B−) in the presence of dodecaethylene glycol (DDEG, L) has been investigated. The equilibrium data have been explained assuming
that the species HL+, H2L2+, CsL+ and CsHL2+ (L = DDEG) are extracted into the organic phase. The values of extraction and stability constants of the complex species
in nitrobenzene saturated with water have been determined.