Approaches to rehabilitation of radioactive contaminated territories

BACKGROUND: Accidents at nuclear fuel cycle plants may lead to contamination of areas of land and water. Cheap and available sorbents including natural aluminosilicates can be used for rehabilitation and decontamination of large volumes of radioactively contaminated water, including drinking water, prevention of migration of radionuclides into ground and surface waters through the soil and returning contaminated soil to farming. RESULTS AND DISCUSSION: A comparative study of sorption properties of various natural and surface-modified aluminosilicates with respect to caesium is made. It is shown that sorption features of surface-modified aluminosilicates for Cs were improved by 100-1000 times compared with respective natural aluminosilicates. It is shown that surface modification of glauconite by a mixed nickel-potassium ferrocyanide phase allows it to considerably increase its specificity (caesium distribution coefficients (2.9 ± 0.8)Ч103 mL g-1 for natural and (4.5 ± 0.5)Ч105 mL g-1 for modified glauconite) as well as making it selective to caesium in the presence of other alkaline ions and also provides irreversible caesium sorption. CONCLUSIONS: Due to improved features, modified aluminosilicates can be more successful than natural ones when used for rehabilitation of radioactive contaminated territories (including agriculture) and water areas, as well as for decontamination of liquid radioactive wastes and for creation of geochemical barriers in solid radioactive waste storage. © 2013 Society of Chemical Industry

COMPARATIVE STUDY OF THE CESIUM UPTAKE ABILITY BETWEEN HEU-TYPE (CLINOPTILOLITE-HEULANDITE) ZEOLITIC TUFF AND PURE HEULANDITE

Specific continuous layers of zeolitic tuff in Ntrista stream location of Petrota area of Evros region (NA11) and pure natural crystals of heulandite (HEU1) from the collection of the Department of Mineralogy-Petrology-Economic Geology, School of Geology, Aristotle University of Thessaloniki, have been investigated. The X-Ray Diffraction analyses showed that the sample NA11 consists of 86 wt% HEU-type zeolite, 4 wt% micas+ clay-minerals, 4 wt% quartz, 2 wt% christobalite and 4 wt% feldspars, while the sample HEU1 is pure heulandite crystal. The mineral-chemistry was determined by SEM-EDS microanalyses. The zeolite of the NA11 sample is Ca-rich clinoptilolite and its chemical formulae is Ca1.8K1.0Mg0.7Na0.5Al6.4 Si29.5O72·21H2O, while the zeolite of the sample HEU1 is heulandite and its chemical formulae is Ca3.6Na1.0Κ0.2Sr0.2Ba0.1Al8.1Si27.6O72·21H2O. The uptake ability of the samples was measured by the AMAS method (Ammonium Acetate Saturation). The two examined materials show high uptake ability. The measured value for the zeolitic tuff NA11 is 231 meq/100g, while for the heulandite crystal (HEU1) is 296 meq/100g. For the determination of the cesium sorption a CsNO3 solution (concentration 500 mg/L), labelled with small activity of 137Cs, and pH 2-12 was used. The sorption of the cesium by the two materials, was determined by measuring the gamma radiation emitted by the 137Cs tracer. The zeolitic tuff presents higher uptake ability of radioactive cesium than the pure heulandite crystal, whereas the sorption of radioactive cesium is not significantly affected by the pH values of the initial solutions in the range pH 2-12.The clinoptilolitic zeolitic tuff NA11 is suitable material for various environmental, agricultural and industrial applications

Application of Accelerator-based Analytical Techniques to the Study of Geological Materials

This contribution provides a short presentation of the applications of the most common accelerator-based analytical techniques to the earth sciences. These techniques offer high elemental selectivity and sensitivity as well as the possibility to determine the lateral and depth distribution of the elements under investigation in near-surface layers of geological materials and provide a powerful tool of investigation of geological, mineralogical, geochemical and cosmochemical processes.</jats:p