Adsorption Of 137Cs Research Articles

Synthesis and Application of MnO-Fe2O3 Nanocomposites for the Removal of 137Cs and 60Co Radionuclides from Artificial Radioactive Aqueous Waste

For innovative application in wastewater treatment techniques, MnO-Fe2O3 nanocomposites were successfully synthesized using the sol–gel auto-combustion method at different temperatures for the adsorption of 137Cs and 60Co radionuclides from aqueous solution. The characterization of these nanocomposites was carried out through FT-IR, SEM-EDX, and X-ray diffraction. These nanocomposites were employed as adsorbent materials for the removal of 137Cs and 60Co radionuclides from simulated radioactive waste solutions. The study involved a series of experiments aiming to demonstrate the MnO-Fe2O3 nanoparticles’ exceptional adsorption potential concerning 137Cs and 60Co. Additionally, the investigation delved into how variations in temperature, dose amount, contact time, and pH value influence the adsorption dynamics. Due to their high specific surface area, the synthesized MnO-Fe2O3 nanoparticles had high adsorption capacity of more than 60% and 90% for 137Cs and 60Co, respectively. By investigation of kinetics and adsorption isotherms, pseudo-second-order reaction and the Langmuir model turned out to fit well for the adsorption of 137Cs and 60Co onto the MnO-Fe2O3 nanocomposites. Moreover, a thermodynamic analysis revealed that the adsorption process was spontaneous for both target metals and the adsorption of 60Co was endothermic, whereas the adsorption of 137Cs was exothermic.

Prussian blue nanoparticles–mediated sensing and removal of 137Cs

Prussian blue nanoparticles (PBNPs) with controlled nano-geometry were synthesized from a single precursor (potassium hexacyanoferrate) in the presence of three different reagents, namely, polyethylenimine (PEI), tetrahydrofuran (THF)/H2O2, and 2-(3,4-epoxycyclohexyl)-ethyl-trimethoxysilane (EETMS)/cyclohexanone, which enabled the controlled nucleation and stabilization of PBNPs of variable plasmonic activities for selective sensing and removal of cesium radionuclides. The results of this study show the sensing and removal of cesium ions based on the nano-geometry, magnetic behavior, and fluorescence quenching ability of PBNPs as a function of the cesium ion concentration for the first time. A similar process was used to synthetically incorporate PBNPs in mesoporous silica with potential use for the selective adsorption of 137Cs, followed by the detection of radioactivity. The distribution coefficient (Kd) for adsorption of the cesium nuclide 137Cs was calculated to be 3.2 × 104 mL/g−1, displaying both Langmuir and Freundlich adsorption isotherms. The plasmonic activity of PBNPs has enabled fluorometric sensing of cesium ions; regulating the spatial control between the functional PBNPs and fluorescence probe molecules is a promising approach for PBNP-enhanced fluorescence and fluorescence resonance energy transfer–based cesium ion sensing. Similarly, PBNPs display superparamagnetic behavior; these magnetic properties were observed to be linearly dependent on the cesium ion concentration.

Photoinduced enhancement of 137Cs removal by NiFe Prussian blue analogue-alginate hydrogel

Prussian blue analogues are promising materials for 137Cs removal; however, their use is limited by the challenge of separating them from an aqueous solution after 137Cs adsorption. This study synthesized a NiFe embedded alginate hydrogel (NiFe-AH) via cross-linking with Ni2+. The prepared NiFe-AH exhibited an excellent performance for Cs+ adsorption. The adsorption capacity of NiFe-AH under UV (0.891 mmol/g) or visible light irradiation (0.885 mmol/g) increased approximately 1.5 times more than before light irradiation (0.591 mmol/g). Moreover, the volume and weight of NiFe-AH after Cs+ adsorption decreased substantially, showing advantage in radioactive nuclide disposal. NiFe-AH exhibited high Cs+ adsorption capacity in all pH ranges, even in the presence of competing ions such as Na+, K+, Ca2+, and Mg2+. Compared to commercialized Cs+ adsorbents (AMP-PAN and KNiFe-PAN), NiFe-AH proved to have a greater Cs+ adsorption capacity. Analyses using XPS and XANES indicated that the photoinduced enhancement mechanism of Cs+ adsorption on NiFe-AH was attributed to NiFe absorbing the light, resulting in the reduction of Fe(III) to Fe(II) within NiFe. Accordingly, Cs+ ions were additionally adsorbed on NiFe. The NiFe-AH showed exceptional 137Cs removal in seawater, suggesting that it has strong potential as a practical adsorbent.

Bentonite phosphate modified with nickel: Preparation, characterization, and application in the removal of 137Cs and 152+154Eu

The present study concerns the sorption of 137Cs and 152+154Eu from low-level radioactive waste (LLW) by bentonite phosphate modified with nickel (BPN) sorbent material. BPN was synthesized using the precipitation method and characterized using various analytical techniques such as Fourier transform infrared (FT-IR), scanning electron microscope (SEM), X-ray fluorescence (XRF), and X-ray diffraction (XRD). The sorption data show that 90 min is enough time to reach equilibrium. The distribution coefficients of 137Cs and 152+154Eu were studied as a function of pH. The distribution coefficient Kd was 2122.2 mL g−1 and 1076.5 mL g−1 for 137Cs and 152+154Eu at pH 9 and 4. The adsorption capacity of BPN has values of 31.1 and 28.2 mg g−1 for 137Cs and 152+154Eu, respectively. The effect of interfering species shows that the rate of adsorption of 137Cs and 152+154Eu slightly decreases as the concentration of the interfering species increases. The investigation of BPN for removing 137Cs and 152+154Eu radionuclides was conducted using a real LLW sample. Results showed that the BPN is appropriate to remove 137Cs and 152+154Eu from liquid radioactive waste and can be considered a potential composite for the purification of effluent polluted with these radionuclides.

Analysis of the vertical distribution of 137Cs and 239,240Pu in waterlogged and non-boggy soils by the sequential extraction method

Mobile capabilities of 137Cs, 239,240Pu and some stable element physicochemical forms were studied in soil layers at a depth of 6–8 cm (maximum concentrations of radionuclides) of non-boggy and waterlogged soil cores sampled on the shores of Lake Bedugnis (Lithuania). Soil samples were acidic with small amount of clay (muscovite). The radionuclide activity concentrations were about 2.5 times higher in non-boggy soil. It was explained by different conditions of deposition of radioactive fallout at these sampling sites and density of the soil samples. The value of the exchangeable fraction of radionuclides is shown to be an indicator of their migration capabilities in the soil. Under anaerobic conditions in waterlogged soil (stagnant pore water conditions) and due to the presence of clay admixture, ∼90% of 137Cs was concentrated in the residual fraction and its mobility was low. 239,240Pu was concentrated mainly in organic matter with rather large exchangeable fractions (∼9.6–∼13.9%). Under oxidizing conditions in non-boggy soil (dynamic pore water conditions in the case of rain), 239,240Pu was mostly concentrated in the oxide fraction. Its exchangeable fractions were less than those in waterlogged soil and, respectively, its mobility was lower. In non-boggy soils, exchangeable fractions of 137Cs were large and varied in the range of 10.1–12.2%, which indicated its high mobility. In the case, 137Cs adsorption by clay materials was reduced and its residual fraction did not exceed 71.3%. The obtained data show that in the area of Lake Bedugnis, the migration capabilities of 137Cs and 239,240Pu change in antiphase.

Decontamination of actual radioactive wastewater containing 137Cs using bentonite as a natural adsorbent: equilibrium, kinetics, and thermodynamic studies

Batch adsorption treatment using Iraqi bentonite as a natural adsorbent was adopted in this study to decontaminate actual 137Cs radioactive wastewater from the Al-Tuwaitha Nuclear Research Center, located south of Baghdad. The bentonite characterization was applied before and after treatment, using chemical compositions analyses, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) surface area analysis and Fourier-transform infrared spectroscopy (FT-IR). The batch adsorption mode was applied with the initial radioactivity concentration (1440.5 Bq/L), solid/liquid ratio (1 g/L), pH (6–8), contact time (1.5 h), and temperature (298°K). The adsorption experiments showed a decontamination removal efficiency of about 95.66% of 137Cs. A Freundlich adsorption isotherm model was approved for the adsorption of 137Cs, with a coefficient of determination R2 = 0.998. A pseudo-second-order model fitted well with the adsorption of 137Cs, with R2 = 0.983. The positive value of ΔH° in the thermodynamic results indicated that the adsorption process was endothermic physisorption (ΔH° = 15.01 kJ mol−1), spontaneous and favorable (ΔG° = −7.66 kJ mol−1 K−1), with a very low degree of disorder (ΔS° = 0.076 kJ mol−1 K−1).

Study of the 137Cs adsorption performance of ion-eroded cement

Study of the 137Cs adsorption performance of ion-eroded cement

Application of solid waste as an adsorbent for capture of 137Cs, 85Sr and 131I from environmental water

ABSTRACT Caesium, strontium, and iodine radionuclides are produced from uranium fission and they are easily soluble in water through accidents or leakages, such as those occurred at Chernobyl, Three Mile Island, and Fukushima. Thus, developing an economical and effective process for removing these radioisotopes from real water is a progressively important issue. Hence, adsorption of 137Cs, 85Sr, and 131I radionuclides was achieved using a solid waste adsorbent. The solid waste adsorbent is granular activated carbon (GAC) gained from the wasted household water filters. The gained data illustrated that the percentages of uptake for 137Cs, 85Sr, and 131I were 87.6, 85.6, and 82.7%, respectively. Application of GAC for the decontamination of real water as groundwater, river water, tap water, and seawater was achieved. The findings revealed that GAC has the ability to be employed effectively as a hopeful material for the decontamination of radioactive 137Cs, 85Sr, and 131I from the environmental water.

ЩОДО ЗАСТОСУВАННЯ БЕНТОНІТОВИХ ГЛИН ЧЕРКАСЬКОГО РОДОВИЩА ДЛЯ УБЕЗПЕЧЕННЯ ЗАХОРОНЕННЯ РАВ У ПОВЕРХНЕВИХ / ПРИПОВЕРХНЕВИХ СХОВИЩАХ НИЗЬКОАКТИВНИХ ВІДХОДІВ: ДОСЛІДЖЕННЯ СОРБЦІЙНИХ ВЛАСТИВОСТЕЙ БЕНТОНІТІВ

The article is devoted to the study of the barrier properties of bentonite clays from the Cherkasy deposit (Ukraine) as the most promising material for engineered barriers in near-surface disposal facilities for low-level radioactive waste. The work presents a description of the Cherkasy bentonite deposit, in particular, of the most promising II layer of the Dashukivka site, and the composition and properties of the natural and soda-modified (PBA20) bentonites which can be used for safe long-term storage and disposal of radioactive waste. The scanning electron microscope (SEM) images of the samples were made and the chemical and mineral composition of the samples was determined. Based on the obtained data, the Dashukivka bentonite was classified as Al-Fe-montmorillonit. The main rock-forming minerals of the bentonite are montmorillonite (75 ± 3 wt. %) and quartz (20 - 25 wt. %). Infrared spectra of the bentonites in the range of 4000 - 400 cm-1 are typical for dioctahedral Al-smectites and are almost identical both for the natural and modified samples. The derivatographic analysis (DTA) of the bentonite samples allows us to conclude that the modified bentonite PBA-20 has greater thermal stability than the natural bentonite. The total weight loss of the samples is about 10.3% and 17.8%, respectively. From the experimental study of 137Cs adsorption from a simulated ChEZ water solution (mineralization – 0.2 g/dm3), it was found that the equilibrium in the sorbent-solution system is established within 12 to 14 h, and the degree of adsorption on the modified bentonite PBA-20 reaches 93%. The degree of adsorption on the natural bentonite is 7 - 10% lower. Analysis of the partition coefficients (Kd) also indicates a higher efficiency of the Na-modified bentonite compared to the natural, and that ion exchange is the main mechanism of caesium adsorption. Increasing of the pH of the initial solution results only in a slight increase of the degree of adsorption. The degree of 137Cs adsorption on Na-modified bentonite is practically independent of the initial concentration of Ca2+ (from 16 to 160 mg/dm3) and Na+ (from 6 to 60 mg/dm3) in the solution. However, 137Cs adsorption on natural bentonite decreases with the increase in Na+ concentration. Thus, the bentonite clays from the Cherkasy deposit (Dashukivka site, II layer) having good barrier properties can be recommend as anti-migration engineered barriers for radioactive waste repositories, in particular, near-surface storage facilities I and II line of Vector complex

A modeling study on the oceanic dispersion and sedimentation of radionuclides off the coast of Fukushima

We developed a three-dimensional prognostic oceanic dispersion model that accounted for the phase transfer of radionuclides between seawater, suspended particles, and seabed sediments with multiscale grain sizes. A detailed hindcast of 137Cs in the seabed sediment off the Fukushima coast was conducted to investigate the transfer mechanism of dissolved 137Cs derived from the Fukushima Daiichi Nuclear Power Plant (FNPP1) accident toward the seabed sediment. Extensive model-data comparison demonstrated that the model could satisfactorily reproduce the oceanic structure and 137Cs concentrations in the seawater and seabed sediment. The model successfully reproduced the major features of the observed spatial variation of the 137Cs activities in the sediment, which represented more than 90% of the sedimentary radiocesium existing in the coastal area off Fukushima several months after the accident. Shear stress associated with the resuspension of the seabed sediment was induced by waves near the shore and by current velocity offshore of the study area. The adsorption of 137Cs on the seabed sediment differed depending on the particle size, with adsorption on clay being the most substantial. The distribution of 137Cs in the sediment off the Fukushima coast was formed mainly owing to adsorption from the dissolved phase by June 2011, when the impact of the direct oceanic 137Cs release from FNPP1 was remarkable. After June 2011, seabed sediment became a source of 137Cs released to the seawater owing to resuspension with and desorption from the sediment.

Active and selective removal of Cs from contaminated water by self-propelled magnetic illite microspheres

We report the fabrication of clay-mineral-based Janus microspheres that exhibit remotely steerable self-propulsion in water, facilitating their selective and active removal of radiocesium from a contaminated solution. The spray-drying of slurries of intrinsically Cs-selective illite containing iron oxide nanoparticles led to magnetic illite microspheres with superior 137Cs adsorption capability and superparamagnetic behavior. The Janus micromotor adsorbent was prepared by depositing catalytic Pt onto the half-surface of magnetic illite microspheres. The micromotor adsorbents exhibited self-propulsion at speeds as high as ~265 µm/s via asymmetric bubble generation in water containing H2O2 as a fuel. The self-propulsion of the adsorbent improved the Cs adsorption kinetics six-folds compared with the kinetics in the corresponding stationary liquid. The magnetic properties of the micromotor adsorbent enabled convenient separation and direction control of the adsorbents under an external magnetic field. In particular, the micromotor adsorbent could successfully remove more than 98.6% of 137Cs from aqueous media containing competing ions including K+, Na+, Ca2+ and Mg2+.

Effect of settling time on the adsorption of 137Cs onto AMP in the AMP-coprecipitation method

Ten sets of experiments with different settling times were conducted to investigate the effect of settling time on the adsorption of 137Cs in seawater onto ammonium phosphomolybdate (AMP). The weight yields of AMP and 137Cs yields in all groups were generally higher than 90%. The average weight yields of AMP in each group varied from 91.8 ± 0.5 to 95.9 ± 0.6% (1 SD), and the average 137Cs yields in each group varied from 88.3 ± 3.0 to 97.8 ± 3.7% (1 SD). The results showed that equilibrium between Cs and AMP is established immediately after the addition of stable Cs carrier and AMP, implying that the solution could be filtered immediately after the coprecipitation forms. IAEA seawater proficiency test exercises also confirmed that the AMP precipitate does not need to be treated statically in the case of 2 g AMP and 3.7 mg Cs carrier in a seawater sample solution. The modified AMP preconcentration method simultaneously meets the requirements of routine and nuclear emergency monitoring of 137Cs in seawater.

Roll-to-roll production of a cellulose filter with immobilized Prussian blue for 137Cs adsorption

• A roll-to-roll method for fabricating cellulose filters with PB was suggested. • The physical properties and Cs adsorption were similar to batch synthesis method. • An adsorbent dosage of 0.05 g/L enabled a >95 % decontamination of 137 Cs. • The filtration test revealed that a 95 % Cs decontamination was kept for up to 10 h. Nuclear power plant accidents can release radioactive cesium in the water and, thus, proper removal technologies are required. Since Prussian blue can selectively adsorb Cs, studies to attach it onto supporting materials such as activated carbon and filters have been conducted. Here, we propose a roll-to-roll method for fabricating cellulose filters with immobilized Prussian blue easily and in large quantities; the physical properties and Cs adsorption performance of these filters were similar to their counterparts prepared in a conventional batch reactor. We performed batch and continuous filtration experiments to confirm their decontamination performance for radioactive cesium with 300 Bq/L of initial concentration. In the batch test, an adsorbent dosage of 0.05 g/L enabled a >95 % decontamination in 24 h; the continuous filtration experiment revealed that a 95 % decontamination was kept for up to 10 h. The proposed roll-to-roll method could allow the production of several filters for the effective removal of cesium from the water.

Physicochemical and time factors affecting 137Cs transfer through a paddy soil–rice system

ABSTRACT To clarify the factors affecting 137Cs transfer from soil to brown rice in comparison with 133Cs transfer and also to determine the key parameters of the solid-liquid partition coefficient (K d), concentration factor from soil solution to brown rice (CF), and transfer factor from soil to brown rice (TF), we analyzed the results of our previous paper in which a rice pot-culture experiment under different fertilization treatments using three paddy soils in Fukushima 3 years after the Fukushima Daiichi Nuclear Power Station accident was conducted. The TF values for 137Cs were the same as or smaller than the literature values obtained within 2 years of the accident, 2–17 times higher than those for global fallout 137Cs from atmospheric nuclear tests, and 2–20 times higher than those for natural 133Cs. The CF values for 137Cs were negatively correlated with the soil solution K+ concentration. A theoretical approach, under the assumption that 137Cs in soil is mainly adsorbed at the frayed edge site (FES) and ion exchange of 137Cs with K+ and NH4 + ions is in equilibrium, partly explained the variability in the soil solution 137Cs concentrations under different soil and fertilization conditions and suggested that the major portion of 137Cs in soil would be adsorbed in FES under lower K+ and NH4 + concentrations but fixed in the collapsed interlayer sites under higher K+ and NH4 + concentrations, the ranges of which are typically observed in agricultural soils. Our results indicate that the major factors affecting 137Cs transfer from soil to brown rice would be the 137Cs, K+, and NH4 + concentrations in the soil solution and the time elapsed from the deposition of 137Cs, and emphasize the necessity of including the dynamic 137Cs adsorption and fixation process in soil into the TF prediction models applicable to agricultural soils received with periodical fertilizations.

Calculation of 137Cs accumulation by phytomass of MOTLEY herbs

Aim: Large-scale development of soils contaminated with artificial radionuclides is accompanied by mandatory determination of 137Cs accumulation factor by crop production. Materials and Methods: The paper proposes to replace the experimental determination of the accumulation coefficient by a numerical method, which was developed on the basis of ideas about the bioremoval of ions from the soil. Results: The calculated KH values were estimated experimentally using the correlation-regression analysis, which revealed a close relationship between them. It has been established that the bioyield of 137Cs depends on the relative transpiration of grass crops or the availability of soil moisture by the root system of plants. Conclusion: It was revealed that the process of 137Cs adsorption by the root system of grasses is more intensive in the period from the renewal of vegetation to the first cut as compared with the period from the first to the second cut.

Polymeric coatings for surface decontamination and ecofriendly volume reduction of radioactive waste after use

A magnet-sensitive and strippable polymeric coating that consists of a magnetic adsorbent with 137Cs adsorption properties using a polyacrylamide (PAAm)/alginate(Alg)-based hydrogel with highly elastic properties was developed for surface decontamination. The aqueous polymeric solution of PAAm and Alg containing adsorbent could be easily applied to 137Cs-contaminated surfaces via the brush method. The simple addition of calcium ions on the surface induced the formation of an adsorbent/PAAm-Alg hydrogel film that could easily peel away from decontaminated surfaces due to its high elasticity. This polymeric coating displayed a good removal efficiency of 96.53% and a decontamination factor (DF) of 28.85 for 137Cs-contaminated surfaces due to the presence of the adsorbent, which had a large distribution coefficient for Cs (3.34 × 104 mL/g), and the large amount of Cs chelating groups in the Alg and PAAm, such as carboxyl and amine groups. The generated volume of the radioactive wastes after surface decontamination was simply reduced due to the magnetic separation of the adsorbent from the used polymeric coating. Furthermore, this new ecofriendly volume reduction method for radioactive waste demonstrated the reusability of PAAm and Alg for further surface decontamination because almost all of the 137Cs (99.838%) captured in the used polymeric coating was removed by magnetic separation of the adsorbent. Therefore, the adsorbent/PAAm-Alg-based polymeric coating system has excellent potential as a new cost-effective surface decontaminant.

Polyvinyl alcohol-borate hydrogel containing magnetic adsorbent for surface decontamination

A stimuli-sensitive, strippable coating material that consisted of a magnetic field-sensitive adsorbent with excellent 137Cs adsorption and a temperature-sensitive, elastic Poly vinyl alcohol (PVA)-borate hydrogel was developed for the decontamination of 137Cs-contaminated surfaces. The viscous solution of adsorbent/PVA-borate complex can easily be applied to a surface at 50°C, subsequently forming an adsorbent/PVA-borate hydrogel film that is strippable from the surface at room temperature. The film displayed a good removal efficiency of 83.46% and the decontamination factor (DF) of 6.05 from the 137Cs-contaminated surface due to the presence of the adsorbent, which had a large distribution coefficient for Cs (3.34×104mL/g). Moreover, the PVA-borate complex can be reused following a simple addition of water via the magnetic separation of the adsorbent, which can capture 99.071% of the 137Cs in the used hydrogel film. These findings suggest a new eco-friendly volume-reduction method for radioactive waste after surface decontamination.

Modeling dynamics of 137Cs in forest surface environments: Application to a contaminated forest site near Fukushima and assessment of potential impacts of soil organic matter interactions

A process-based model for 137Cs transfer in forest surface environments was developed to assess the dynamic behavior of Fukushima-derived 137Cs in a Japanese forest. The model simulation successfully reproduced the observed data from 3year migration of 137Cs in the organic and mineral soil layers at a contaminated forest near Fukushima. The migration of 137Cs from the organic layer to the mineral soil was explained by the direct deposition pattern on the forest floor and the turnover of litter materials in the organic layer under certain ecological conditions. Long-term predictions indicated that more than 90% of the deposited 137Cs would remain within the top 5cm of the soil for up to 30years after the accident, suggesting that the forest acts as an effective long-term reservoir of 137Cs with limited transfer via the groundwater pathway. The model was also used to explore the potential impacts of soil organic matter (SOM) interactions on the mobility and bioavailability of 137Cs in the soil–plant system. The simulation results for hypothetical organic soils with modified parameters of 137Cs turnover revealed that the SOM-induced reduction of 137Cs adsorption elevates the fraction of dissolved 137Cs in the soil solution, thereby increasing the soil-to-plant transfer of 137Cs without substantially altering the fractional distribution of 137Cs in the soil. Slower fixation of 137Cs on the flayed edge site of clay minerals and enhanced mobilization of the clay-fixed 137Cs in organic-rich soils also appeared to elevate the soil-to-plant transfer of 137Cs by increasing the fraction of the soil-adsorbed (exchangeable) 137Cs. A substantial proportion (approximate 30%–60%) of 137Cs in these organic-rich soils was transferred to layers deeper than 5cm decades later. These results suggested that SOM influences the behavior of 137Cs in forests over a prolonged period through alterations of adsorption and fixation in the soil.

Evaluation of Chlorella as a Decorporation Agent to Enhance the Elimination of Radioactive Strontium from Body.

BackgroundRelease of radionuclides, such as 137Cs and 90Sr, into the atmosphere and the ocean presents an important problem because internal exposure to 137Cs and 90Sr could be very harmful to humans. Chlorella has been reported to be effective in enhancing the excretion of heavy metals; thus, we hypothesized that Chlorella could also enhance the elimination of 137Cs or 90Sr from the body. We evaluated the potential of Chlorella as a decorporation agent in vitro and in vivo, using 85Sr instead of 90Sr.MethodsIn vitro experiments of adsorption of 137Cs and 85Sr to Chlorella were performed under wide pH conditions. The maximum sorption capacity of Chlorella to strontium was estimated using the Langmuir model. A 85Sr solution was orally administrated to mice pretreated with Chlorella. At 48 h after 85Sr administration, the biodistribution of radioactivity was determined.ResultsIn the in vitro experiments, although 85Sr barely adsorbed to Chlorella at low pH, the 85Sr adsorption ratio to Chlorella increased with increasing pH. The maximum sorption capacity of Chlorella to strontium was 9.06 mg / g. 137Cs barely adsorbed to Chlorella under any pH conditions. In the biodistribution experiments, bone accumulation of radioactivity after 85Sr administration was significantly decreased in the Chlorella pretreatment group compared with the non-treatment control group.ConclusionsIn conclusion, these results indicated that Chlorella could inhibit the absorption of 90Sr into the blood and enhance the elimination of 90Sr from the body through adsorption in intestine. Further studies are required to elucidate the mechanism and the components of Chlorella needed for adsorption to strontium and could promote the development of more effective decorporation agents.

Adsorption behavior of a carbonized paper sludge towards 137Cs

The adsorption of 137Cs by a carbonized paper sludge (PSC) was studied using the original and its modified form (PFC-PSC) by impregnating with 1 % potassium ferrocyanide. The distribution coefficient of PSC decreases with increasing Cs+ concentration in 137Cs solutions whereas that of PFC-PSC is highest at around and lower than 60 Bq ml−1. The Freundlich constant of PFC-PSC is much higher than that of PSC, suggesting that the 137Cs affinity of the former is higher than the latter. The pseudo second order rate constant of PSC decreases but that of PFC-PSC increases with decreasing Cs+ concentration.