Ana Lazić

In the context of the expanding nuclear energy industry and the increasing need for emergency preparedness, the development of rapid, reliable, and efficient methods for environmental radioactivity monitoring is of great importance. This study evaluates rapid methods for the determination of the beta-emitting fission products 90Sr and 3H in drinking water samples collected from different cities across the Republic of Serbia. Measurements were performed using an ultra-low- background liquid scintillation counter. The activity concentrations of 90Sr and 3H in all analyzed samples were below the minimum detectable activities (MDA) of 0.55 Bq/L and 2.4 Bq/L, respectively. In addition, the pH and electrical conductivity of the water samples were determined to characterize their basic physicochemical properties. The study also systematically evaluates the detector counting efficiency and MDA, demonstrating the applicability of the proposed methods for fast radiological emergency response.

This work used activated carbon material obtained by chemical activation of abundantly available agricultural sunflower waste residues to remove metol (4-(methylamino) phenol sulfate, MTL) from aqueous solutions. The adsorbent structure was characterized using SEM-EDS and FT-IR spectroscopy. A modified screen-printed carbon electrode (SPCE) with gold nanoparticles synthesized using the Laser Ablation Synthesis in Solution (LASIS) method was used to detect MTL. The successful LASIS formation of gold nanoparticles was confirmed by the specific dark burgundy–red color. TEM measurements showed uniform pseudo-spherical particles with an average diameter of 7.9 ± 0.2 nm. The modified electrode showed improved electrochemical activity, which was confirmed by comparing it with an unmodified electrode using cyclic voltammetry and electrochemical impedance spectroscopy. The modified electrode was subsequently used to optimize the MTL detection conditions. UV–Vis spectroscopy was used to optimize the adsorption conditions, with the optimal values for pH and contact time found to be 8 and 120 min, respectively. The electrochemical detection of MTL was performed using differential pulse voltammetry, and the linear calibration range was established for concentrations ranging from 0.73–49.35 µM. The obtained limits of detection (LOD) and quantification (LOQ) were 0.06 µM and 0.2 µM, respectively. The efficiency of MTL removal was 100% after a contact time of 1 min and remained at 100% after 120 min.