Band 112, Heft 5

The assessment of the migratory and environmental behavior of radioactive nuclides escaping from waste treatment facilities heavily relies on the use of numerical models capable of simulating and characterizing all significant processes of nuclides in complex geological environments. Adsorption models typically encompass the chemical properties of the nuclides themselves and their chemical reactions with the surrounding environment, as well as processes such as ion exchange or physical adsorption. These processes must be taken into consideration in the long-term safety assessment of radioactive waste repositories. The redox-sensitive nuclide 238 Pu, a critical member among transuranic elements, exhibits a diverse range of aqueous forms, and concurrently, it possesses high toxicity. The chemical behavior of 238 Pu shows strong spatial variability with changes in environmental conditions. In this study, we constructed a theoretical model for the migration of nuclides in soil and groundwater environments through indoor static batch experiments and hydrogeochemical simulations. Experimental methods were employed to dissect the micro-scale, irreversible adsorption reaction processes of nuclides and identify their primary existing forms. According to field measurements, the pH of groundwater was recorded as 7.48, with an Eh of 125.7 mV. Introducing a solid-to-liquid ratio of 1:10 g/mL in centrifuge tubes, we measured the radioactive nuclide concentration after achieving adsorption and desorption equilibrium, obtaining adsorption and desorption isotherms. The PHREEQC software was employed to investigate the changes in 238 Pu forms under varying conditions of pH and redox potential. Field measurements provided groundwater pH and Eh values. The activity concentration of the nuclide was measured after reaching adsorption and desorption equilibrium. The results show that the adsorption isotherms of 238 Pu differ from its desorption isotherms, indicating an irreversible adsorption-desorption process. Ion exchange and surface complexation were identified as the main modes of adsorption. PHREEQC simulations revealed that 238 Pu primarily existed in forms such as tetravalent Pu(OH) 4 and trivalent Pu(SO 4 ) 2 − , PuSO 4 + . Pu(OH) 4 accounted for the largest proportion (97%) in the groundwater solution system, while a minimal amount of pentavalent PuO 2 + was present. Environmental factors, such as pH and the presence of ions like SO 4 2− and HCO 3 − , influenced the forms of 238 Pu.

With the rapid development of the atomic energy industry, the demand for nuclear fuel has risen, while the limited resources of uranium mines make it difficult to meet the needs of the future development of nuclear energy. Expanding sources of uranium acquisition is necessary, and the enrichment and recovery of precious uranium from uranium-containing wastewater is invaluable. By synthesizing alginate supported potassium manganese ferrocyanide nanocomposites with magnetic response (KMnFC/MA/Fe 3 O 4 ), the high efficiency adsorption and separation of uranium in acidic uranium-containing wastewater can be realized conveniently and quickly. The magnetic composite was characterized by a variety of technical means, and the adsorption behavior of the magnetic material on uranium was studied by static adsorption experiments under different environmental conditions. The adsorption kinetics and isotherm of uranium by KMnFC/MA/Fe 3 O 4 were studied by using some common linear adsorption models. The results show that the adsorption rate of KMnFC/MA/Fe 3 O 4 on uranium is fast, and the adsorption equilibrium can be reached within 90 min. The adsorption process conforms to a pseudo-secondary kinetic model and is dominated by chemisorption. The adsorption of uranium by KMnFC/MA/Fe 3 O 4 magnetic material is single molecular layer adsorption, and the maximum adsorption capacity is 425.5 mg g −1 at 35 °C. KMnFC/MA/Fe 3 O 4 is a promising adsorbent in the field of acidic low-concentration uranium wastewater treatment because of its good effect on the treatment of low concentration uranium wastewater, the concentration of uranium in the wastewater reaches the emission standard after treatment and it is easy to be separated magnetically after adsorption.

Selective removal of 99 TcO₄ − from radioactive wastewater is a challenging but significant task, which benefits spent fuel reprocessing and radioactive-waste leakage treatment. This work introduces the performance of adsorption ReO 4 − using a series of novel anion exchange resins, namely MAPE-1, MAPE-2, MAPE-3, and MAGD-1, impregnated with functionalized ionic liquids as active sites. They exhibit a high selectivity towards TcO₄ − /ReO₄ − , in a wide pH range of pH 5–11 for ReO₄ − /TcO₄ − adsorption. Among these resins, MAPE-1 has the best adsorption performance for ReO 4 − , with a maximum adsorption capacity of 202.4 mg/g and a high distribution ratio K d of 6.2 × 10⁶ mL/g at pH 7. The adsorption mechanism involves anion exchange between functionalized ionic liquids and TcO₄ − /ReO₄ − , which is supported by X-ray energy dispersive spectroscopy (EDS) and Fourier Transform Infrared spectroscopy (FT-IR) analyses. In addition, X-ray photoelectron spectroscopy (XPS) further illustrates the interaction between the resin and perrhenate.

Xanthomicrol (4′,5-dihydroxy-6,7,8-trimethoxyflavone) is the main active component of Dracocephalum kotschyi Boiss leaf extract. It has showed selective cytotoxic activity against some cancer cell lines and little effect on human fetal foreskin fibroblast cells used as nonmalignant control. This study aimed to develop 99m Tc-labeled xanthomicrol and to evaluate its efficiency as a new tumor imaging agent. l , l -Ethylene dicysteine (EC) chelator was conjugated to xanthomicrol. EC-Xanthomicrol was labeled with technetium-99m by using tin chloride as a reducing agent and incubating at room temperature. Radiochemical purity and in vitro stability were analyzed by thin layer chromatography and high-performance liquid chromatography. In vitro cellular uptake and binding profile of radio-conjugate was determined on C6 glioma cells. In vivo bioevaluation and imaging studies of [ 99m Tc]Tc-EC-Xanthomicrol were performed in C6 glioma tumor induced rat at different time points after injection of radio-conjugate. The high radiochemical yield (>95 %) was achieved for [ 99m Tc]Tc-EC-Xanthomicrol which was stable up to 6 h. The radio-conjugate indicated high cell uptake (35.12 % at 2 h) which demonstrated to be specific. Tumor uptake was seen for [ 99m Tc]Tc-EC-Xanthomicrol (1.23 ± 0.14 %ID/g) at 1 h post injection. Scintigraphy confirmed that tumors could be visualized clearly with [ 99m Tc]Tc-EC-Xanthomicrol. The results indicated that [ 99m Tc]Tc-EC-Xanthomicrol has potential to be considered as a new radiotracer in glioma tumor imaging.

The purpose of this research is to produce composites of epoxy resin and calcium carbonate (EP/CaCO 3 ) and investigate how treating the CaCO 3 filler with stearic acid and gamma radiation affects the properties of the epoxy composites, enhancing their suitability for a range of applications. The CaCO 3 powder was subjected to stearic acid treatment and later exposed to γ -radiation at various doses namely (10, 20 and 30 kGy), Different weight percentages of untreated and treated CaCO 3 powder were added to epoxy resin (EP) to create EP/CaCO 3 composites loaded with varying amounts of CaCO 3 filler (5 %, 10 %, 20 %, 30 %, and 40 %). The influence of both stearic acid treatment and different doses of gamma radiation on CaCO 3 was investigated. The composites were subjected to characterization of various properties including mechanical (splitting tensile strength, impact strength), thermal (TGA and dimensional thermal analysis) as well as morphological SEM examination. The analysis’ findings demonstrated that the stearic acid monolayer functions as a coupling agent in the EP matrix and can coat CaCO 3 particles efficiently. The modification of CaCO 3 by stearic acid and exposure to 30 kGy of gamma radiation shows a notable improvement in thermal stability and mechanical qualities for the epoxy composites loaded with various CaCO 3 concentrations.

The main objective of this research is to assess how gamma radiation influences the chemical composition and activities such as antioxidant, antimicrobial and anticancer activities of Lepidium sativum ( L. sativum ) seeds. Methanolic extracts were obtained through a 24 h maceration process from L. sativum seeds exposed to various doses of gamma irradiation. Phytochemical screening involved precipitation and staining reactions, with the antioxidant potential assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Antimicrobial activity was evaluated through a diffusion test on agar medium, while the cytotoxic potential on the lung cancer line “A-549 cells” was examined using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Qualitative analysis of the extracts identified preserved bioactive constituents after irradiation. Additionally, quantitative analysis indicated a significant rise in the total content of polyphenols and flavonoids under radiation, accompanied by an enhanced reducing power compared to the control. The antimicrobial and cytotoxic capabilities also improved, evident in increased growth inhibition zones for certain microbial strains and reduced viability rates of A549 cells. These results show promise and warrant further investigation into the potential of gamma radiation to enhance additional biological effects of plants.