Methods of Thermal Treatment of Radioactive Waste

Throughout the world, and especially in the European Union, numerous technologies for the thermal treatment of radioactive waste are available or being developed. These technologies can be applied to a large range of different radioactive waste streams, including non-standard types of waste that present specific waste management challenges. Thermal treatment can result in a significant reduction in volume and hazard, which are beneficial for safe storage and disposal. Thermal treatment also removes organic material that can form complexing agents and increase the mobility of radionuclides in the landfill. In the paper, basic thermal techniques are presented, and some examples of the installations are shown. Common knowledge of these methods may result in an increased public acceptance of nuclear energy in a country just introducing it, as Poland is.

Development of a new highly sensitive and selective spectrophotometric method for the determination of selenium at nano-trace levels in various complex matrices using salicylaldehyde-orthoaminophenol

A new spectrophotometric reagent, salicylaldehyde-orthoaminophenol (Sal-OAP) has been synthesized and characterized for the determination of selenium through novel reaction techniques. Also, a new highly selective, and sensitive spectrophotometric method for the nano-trace determination of selenium using salicylaldehyde-orthoaminophenol (Sal-OAP) has been developed. Sal-OAP undergoes reaction in a slightly acidic solution (0.0001-0.0002 M H2S04) with selenium (IV) to give an orange-red chelate, which has an absorption maximum at 379 nm. The reaction is instantaneous and absorbance remains stable for over 24 h. The average molar absorption co-efficient and Sandell’s sensitivity were found to be 6.4×105 L/mol.cm and 1.0 ng/cm2 of, respectively. Linear calibration graphs were obtained for 0.001-40.000 mg/Lof Se having detection limit of 0.1 µg/L and RSD 0-2 %. The stoichiometric composition of the chelate is 1:2 (Se:Sal-OAP). A large excess of over 60 cations, anions and some common complexing agents, such as chloride, azide, tartrate, EDTA, SCN¯etc., do not interfere in the determination. The developed method was successfully used in the determination of selenium in several Certified Reference Materials (Alloys, steels, human urine, bovine liver, drinking water, tea, milk, soil, and sediments) as well as in some environmental waters (Potable and polluted), biological fluids (Human blood, urine, hair, and milk), soil samples, food samples (Vegetables, rice, and wheat) and pharmaceutical samples (Tablet and syrup) and solutions containing both selenium (IV) and selenium (VI) as well as complex synthetic mixtures. The results of the proposed method for assessing biological, food and vegetables and soil samples were comparable with ICP-OES and AAS were found to be in excellent agreement. The method has high precision and accuracy (s = ±0.01 for 0.5 mg/L).

pH-metric method determining the solubility and solubility products of slightly soluble salts of arbitrary composition

The developed method of determining KS from pH metric data has a number of advantages compared to those used traditionally. First, in place of the residual concentrations of the salt components, only the pH value of the saturated solution is used in the derived expressions. Thus, the number of independent variables, which need to be measured experimentally, is reduced. Furthermore, the potentiometric method, used to determine the pH, is sufficiently accurate, simple and universal and does not necessitate the use of ion-selective electrodes. At the same time, the residual concentrations are usually measured by chemical methods, which are inferior in most cases, for several reasons, compared to the potentiometric method. Second, the KS value calculated by the developed method has a thermodynamic character. The organization of the experiment must be appropriate to the applied equations. Therefore, it is necessary to draw attention to the need for high accuracy in the process of preparing the initial solutions, because the initial concentrations of the precipitate components are included in the calculation formulas. The developed method for determining Ks can be applied for systems of any degree of complexity, which contain additional complexing agents.

Strippable Polymeric Nanocomposites Comprising “Green” Chelates, for the Removal of Heavy Metals and Radionuclides

The issue of heavy metal and radionuclide contamination is still causing a great deal of concern worldwide for environmental protection and industrial sites remediation. Various techniques have been developed for surface decontamination aiming for high decontamination factors (DF) and minimal environmental impact, but strippable polymeric nanocomposite coatings are some of the best candidates in this area. In this study, novel strippable coatings for heavy metal and radionuclides decontamination were developed based on the film-forming ability of polyvinyl alcohol, with the remarkable metal retention capacity of bentonite nanoclay, together with the chelating ability of sodium alginate and with “new-generation” “green” complexing agents: iminodisuccinic acid (IDS) and 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC). These environmentally friendly water-based decontamination solutions are capable of generating strippable polymeric films with optimized mechanical and thermal properties while exhibiting high decontamination efficiency (DF ≈ 95–98% for heavy metals tested on glass surface and DF ≈ 91–97% for radionuclides 241Am, 90Sr-Y and 137Cs on metal, painted metal, plastic, and glass surfaces).

Adjusting the Structure of β-Cyclodextrin to Improve Complexation of Anthraquinone-Derived Drugs

β-Cyclodextrin (CD) derivatives containing an aromatic triazole ring were studied as potential carriers of the following drugs containing an anthraquinone moiety: anthraquinone-2-sulfonic acid (AQ2S); anthraquinone-2-carboxylic acid (AQ2CA); and a common anthracycline, daunorubicin (DNR). UV-Vis and voltammetry measurements were carried out to determine the solubilities and association constants of the complexes formed, and the results revealed the unique properties of the chosen CDs as effective pH-dependent drug complexing agents. The association constants of the drug complexes with the CDs containing a triazole and lipoic acid (βCDLip) or galactosamine (βCDGAL), were significantly larger than that of the native βCD. The AQ2CA and AQ2S drugs were poorly soluble, and their solubilities increased as a result of complex formation with βCDLip and βCDGAL ligands. AQ2CA and AQ2S are negatively charged at pH 7.4. Therefore, they were less prone to form an inclusion complex with the hydrophobic CD cavity than at pH 3 (characteristic of gastric juices) when protonated. The βCDTriazole and βCDGAL ligands were found to form weaker inclusion complexes with the positively charged drug DNR at an acidic pH (pH 5.5) than in a neutral medium (pH 7.4) in which the drug dissociates to its neutral, uncharged form. This pH dependence is favorable for antitumor applications.