DOI: https://doi.org/10.31258/Jamt.6.1
Published: Jan 9, 2025
Articles
Assessing immobilization matrices for nuclear effluent treatment: Cs case study
The immobilization processes for nuclear waste have gained significant attention from the scientific community due to the growing global activity in the nuclear industry. Although these processes have been studied and applied since the mid-20th century, many questions remain that require further in-depth research, including the immobilization itself and the deposition of wasteforms in repositories designed to safeguard against future exposure. In this study, highly phase-pure zeolite A was synthesized via hydrothermal processing of coal fly ash from a Brazilian thermal power plant and loaded with Cs to evaluate thermal stability, structure, and immobilization in Nb-aluminoborosilicate and geopolymer matrices. Cs adsorption, confirmed by XRD peak intensity and Raman band changes, showed a 26 wt.% incorporation (INAA) after 24-hour sorption using simulated CsCl solution, a notable result given the fly ash impurities. The zeolite structure remained stable during the heating up to 960 °C, forming water-insoluble phases (pollucite and cesium aluminum oxide) right after structural collapse between 700 °C and 900 °C. Up to 40 wt.% of Cs-loaded waste was incorporated into a monolithic ceramic via thermal treatment of Nb-aluminoborosilicate glass and zeolite A at 900 °C for 2 hours, yielding a dense body (2.4 g/cm³) with low porosity (3.6%) and water absorption (1.63%). In contrast, raw Cs-loaded zeolite A showed high porosity (48%), water absorption (33%), and low density (1.44 g/cm³). Crystalline Cs phases formed at lower temperatures (900 °C) due to the devitrification nature of the glass. Geopolymer matrices immobilizing Cs-loaded zeolite exhibited water leachability comparable to similar materials, meeting nuclear waste disposal requirements.

Response surface methodology for glucose conversion by applying deep eutectic solvent (DES) as green solvent
Glucose is a monosaccharide-type carbohydrate that serves as a fundamental building block of biomass. In this research, glucose was hydrolyzed using a Deep Eutectic Solvent (DES) as the solvent and AlCl3 as the catalyst. The effects of temperature and catalyst concentration were investigated as key variables in the reaction. The glucose conversion results were tested using the UV-Vis spectrophotometer. The yields of glucose conversion were analyzed using the Response Surface Methodology (RSM) with Design Expert Version 13 software. The results of RSM analysis show that glucose conversion increases linearly with rising reaction temperature. The effect of catalyst concentration indicates that glucose conversion decreases at higher catalyst levels. The reaction temperature and AlCl3 catalyst concentration that can be recommended for optimum conditions from the Design Expert data processing results are 112.869 C and 1.913% with a predicted conversion value of 93.844%.
