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Abstract  

The interaction of Greek dolomitic marble (from Thassos island, northern Greece) with Co2+, Cd2+, Pb2+ and Cr3+ containing aqueous solutions was studied by characterizing the surface of the solid experimental samples, using a combination of spectroscopic, microscopic, and diffraction techniques (RBS, XPS, SEM-EDS, FT-IR, powder-XRD). The obtained results indicated a considerable Cd2+ and Co2+ sorption on the dissolved surface of the carbonate substrate, whereas, under the same experimental conditions, the Pb2+ and Cr3+ interaction is more intense leading to extended overgrowth of crystalline Pb2+ carbonates and massive surface precipitation of amorphous Cr3+ hydroxide/oxyhydroxide.

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Abstract  

The sorption of uranium from acidic aqueous solutions (pH 4.5, C init = 10 to 1000 mg U/L) by Saccharomyces cerevisiae, Debaryomyces hansenii, Kluyveromyces marxianus and Candida colliculosa was investigated using a batch technique. The U-sorption onto Saccharomyces cerevisiae and Debaryomyces hansenii followed a Langmuir, while that onto Kluyveromyces marxianus and Candida colliculosa a Freundlich isotherm. The results demonstrated that all investigated biomasses could effectively remove uranium from acidic aqueous solutions. From all sorbents, Saccharomyces cerevisiae appeared to be the most effective with a maximum sorption capacity of 127.7 mg U/g dry biomass.

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Abstract  

The interaction of granitic biotite with aqueous solutions of La, Nd, Th and U (concentration 10 to 1000 mg·l-1) was studied using instrumental neutron activation analysis (INAA) and 12C-Rutherford backscattering spectroscopy (12C-RBS). For comparison, the sorption of La and Nd by granitic feldspar and natural zeolite heulandite was also investigated. The experimental results showed that biotite exhibits higher sorption ability towards La and Nd, (maximum uptake 2.09 and 7.98 mg/g, respectively) than the feldspar and the heulandite. The interaction of biotite with Th is also intense, the metal being preferably concentrated at the near-surface layers of the crystals. This indicates that other sorption mechanisms (adsorption and surface precipitation) than ion-exchange take place at the solid/solution interface. The same phenomenon was also observed in the case of U, although the corresponding metal uptake was found to be considerably lower.

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Abstract  

The cross-sections of the32S(3He, p)34mCl nuclear reaction have been determined in the projectile energy region between 4.0 and 12.0 MeV with the aim of their use for the determination of sulfur in surface layers of materials by means of Charged Particle Activation Analysis (CPAA). The measured cross-sections indicate that the application of this reaction for the determination of ppm and sub-ppm concentrations of sulfur is possible depending on the matrix material (e.g. detection limit for S in GaAs is 2 ppm, whereas in Si 300 ppb).

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Abstract  

The sorption of caesium and strontium from its aqueous solutions by ten clinoptilolite-and mordenite-containing sedimentary materials from Slovakia, Bulgaria, Ukraine and Greece was investigated by batch-type procedure and radiotracer techniques. The concentration of the solutions, that were performed in and without the presence of competing cations (0.005 mol·dm−3 KCl) varied between 1·10−4 and 5·10−2 mol·dm−3. The uptake and distribution coefficient (K d ) values determined for the materials of the different origin, were correlated with their mineralogical composition and gross cation exchange capacity (CEC). The identification of the specific uptake sites was attempted on the basis of the sorption isotherms and the content of exchangeable cations. The experimental results provide information on the suitability of the individual materials for the treatment of radioactive wastes and their application as backfills in potential nuclear waste repositories.

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Abstract  

Natural zeolitic materials (sedimentary zeoliferous rocks) were organo-modified using polyhexamethyleneguanidine-chloride in order to enhance their anionic sorptive properties. The sorption of As(V)-anions from aqueous solutions [As(V) concentration range from 10 to 1000 mg/l] was investigated using radiochemical techniques. The samples exhibited an elevated tendency to sorb As(V)-anions (up to 6.73 mg/g) and the relative uptake was found to be much higher for solutions of low initial concentrations (up to 99.8% removal). The different As(V) species (mainly HAsO4 2−) are principally sorbed through ion-exchange reactions by the net of the polymeric, compound covering the mineral aggregates of the samples. The investigated materials could be considered for the removal of As(V) anionic species present in industrial or municipal wastewaters.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
P. Misaelides
,
P. Misaelides
,
P. Misaelides
,
S. Sarri
,
S. Sarri
,
S. Sarri
,
D. Zamboulis
,
D. Zamboulis
,
D. Zamboulis
,
G. Gallios
,
G. Gallios
,
G. Gallios
,
I. Zhuravlev
, and
V. V. Strelko

Summary  

The sorption of europium from aqueous solutions (Eu-concentration: 10 to 250 mg/l) by Fe3+- and Al3+-doped zirconium- and titanium-phosphates was investigated using a batch technique and 152Eu tracer. The initial pH of the solutions was adjusted to 3, 4, 5 and 6. All investigations were performed under constant ionic strength, I=0.15 established by NaCl.Although zirconium phosphates generally showed a higher Eu-uptake capacity than the titanium ones, all investigated materials possessed the ability to remove considerable amounts of europium from aqueous solutions. The Eu-sorption properties of the studied phosphate materialsseem to be not especially affected by the type of trivalent cations used for the doping (i.e., Al3+or Fe3+).

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Abstract  

The uptake of mercury, cadmium and silver from aqueous solutions by unpretreated and NaCl-pretreated clinoptilolite-bearing volcaniclastic rocks from Metaxades (Thrace, Greece) has been studied using a batch method with radioactive tracers (197Hg,115Cd and110mAg). The concentration of the solutions used varied between approximately 1000 and 17000 ppm. An improvement of the uptake ability was observed in the case of NaCl-pretreated material for all the investigated metals and especially for mercury at the upper part of the concentration range studied. The heavy metal uptake is attributed to different mechanisms taking place both at the rock grains and their individual mineral components.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
B. Symeopoulos
,
M. Soupioni
,
P. Misaelides
,
A. Godelitsas
, and
N. Barbayiannis

Abstract  

The sorption of neodymium from its aqueous solutions (concentration range approx. 10–450 mg l–1) by montmorillonite, kaolinite and a clinoptilolite-containing rock has been investigated, using147Nd as radioactive tracer and -ray spectrometry. The neodymium uptake by montmorillonite was found to be much higher than of the other two materials in the whole investigated concentration range. However, in the case of montmorillonite and zeoliferous rock, the uptake ability is lower than that allowed by the measured CEC values and can be described by Langmuir-type equations. In the case of kaolinite, the observed higher than CEC-allowed uptake values could be attributed to sorption by mechanisms other than ion-exchange. The corresponding data obey a Freundlich-type sorption equation. Among the three geological materials investigated, montmorillonite exhibits the highest perspectives of application for the treatment and disposal of neodymium and trivalent actinides in nuclear industry.

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Abstract  

The uranium sorption from aqueous solutions (concentration range 50–20.000 mg/l) by the sodium-form (Na-form) of HEU-type zeolite crystals (particle-size <20 m) has been investigated by means of a batch-type method. The INAA, RI-XRF, powder-XRF, SEM-EDS and FT-IR techniques were used for the study of the experimental products. The absolute uranium uptake by the material reached the value of 11.68 mg/g in the case of initial concentraton 20,000 mg/l. On the other hand theK d -values indicated that the relative uranium uptake, and consequently the percentage of removal, is higher for concentrations below 100 mg/l. The uranium uptake by the zeolite is attributed to different sorption processes such as ion-exchange, adsorption and surface precipitation, taking place both to the interior and the surface of the crystals and strongly depending on the pH of the solutions. The investigated zeolitic material was sufficiently resistant at the low initial pH of the solutions with dealumination phaenomena only observed in the case of the most acidic solution used.

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