Qualification of corroborated real phytoremediated radioactive wastes under leaching and other weathering parameters

Cement-based solidification of nuclear waste: Mechanisms, formulations and regulatory considerations

This review paper provides a comprehensive analysis of cement-based solidification and immobilisation of nuclear waste. It covers various aspects including mechanisms, formulations, testing and regulatory considerations. The paper begins by emphasizing the importance of nuclear waste management and the associated challenges. It explores the mechanisms and principles in cement-based solidification, with a particular focus on the interaction between cement and nuclear waste components. Different formulation considerations are discussed, encompassing factors such as cement types, the role of additives and modifiers. The review paper also examines testing and characterisation methods used to assess the physical, chemical and mechanical properties of solidified waste forms. Then the paper addresses the regulatory considerations and compliance requirements for cement-based solidification. The paper concludes by critically elaborating on the current challenges, emerging trends and future research needs in the field. Overall, this review paper offers a comprehensive overview of cement-based solidification, providing valuable insights for researchers, practitioners and regulatory bodies involved in nuclear waste management.

A new screen-printed electrode for selective determination of bismuth in different authentic samples

A new potentiometric method based on the screen-printed ion-selective electrode (SPISE) was described for the determination of Bi(III) ion in different authentic samples. The novelty is based on, for the first time, the utilization of the cerium zirconium phosphotungstate (CZPT) in a screen-printed electrode (SPE) as a sensing material. In the literature, there is no screen-printed ion-selective electrode for the determination of Bi(III) ion. The influences of the paste composition, different conditioning parameters and foreign ions on the electrode performance were investigated. The reversibility and also response time of the electrode have been studied. The electrode showed a Nernstian response of 18.2 mV decade−1 in the concentration range of 3.3 × 10−7–1 × 10−1 mol. L−1. The electrode was found to be usable within the pH range of 3.5–8.0 and exhibited a fast response time, limit of detection (LOD) (1 × 10−7 mol. L−1), limit of quantification (LOQ) (3.33 × 10−7 mol. L−1), long lifetime and good stability. The matched potential method (MPM) was applied to determine the selectivity coefficient. The isothermal temperature coefficient (dEo/dt) of the electrode was calculated. The electrode was successfully applied for the determination of Bi(III) ion in different authentic samples. By comparing the current results with those obtained using inductively coupled plasma optical emission spectrometry, the nominated Bi(III) screen-printed ion-selective electrode has attained acceptable and efficient performance.

Elaboration of geopolymer package derived from uncalcined phosphate sludge and its solidification performance on nuclear grade resins loaded with 134Cs

Nuclear-grade Spent Organic Resin (SOR) contains high concentrations of radioactive nuclides and metal contaminants, while phosphate sludge contains high amount of fine clayey particles and CO₃^2-, both posing a major threat to the biosphere. In this study, a novel geopolymer package (GP) was proposed to directly solidify SOR loaded with ¹³⁴Cs by incorporating uncalcined phosphate sludge (UPS) as feedstocks, activated by NaOH/KOH. The results showed that alkali-mixed reagents-activated GP is more advantageous in terms of chemical stability and mechanical properties than NaOH-activated GP, recording compressive strength values greater than the waste acceptance criteria and OPC. The 28-day compressive strength of solidified packages can exceed 31 MPa at the highest amount of 42 wt% UPS. The addition of NaF powder into the solidified packages generates more hybrid type gels, which are more conducive to partial dissolution and bonding UPS particles, thereby producing stable and stronger GP. Leaching results of solidified GP in presence of up to 13 wt% SORs showed that only 0.15 % of total ¹³⁴Cs was leached, even under aggressive solutions. Solidification mechanism revealed that activation of UPS-MK blend forms N,K-A-S-H, (N,K,C)-A-S-H/C-S-H gels coexisting with unreacted particles, thereby solidify/stabilize metal contaminants and Cs⁺ by a synergetic immobilization action of hydration products via substitution and encapsulation. This study provides a promising paradigm for effective solidification of nuclear-grade resins and synergetic harmless treatment of industrial/phosphate mine solid wastes.

Elicitation Promoability with Gamma Irradiation, Chitosan and Yeast to Perform Sustainable and Inclusive Development for Marjoram under Organic Agriculture

Sweet marjoram (Majorana hortensis) is an important aromatic herbal plant that has long been used and well managed in the traditional and general medical, pharmaceutical, food, cosmetic, and perfume industries. Thus, the increase in its productivity appears to be of great value since there is a large number of bioactive secondary metabolites as well as an increase in the demand in domestic or foreign markets. The purpose of this study is the possibility of promoting the sustainable development of marjoram in the framework of organic farming through gamma irradiation, chitosan and yeast. Field experiments were conducted in a factorial split-plot design with three iterations over two consecutive seasons (2019 and 2020). The main plot is an abiotic elicitor (15 Gy gamma irradiation), two biotic elicitors 500 ppm chitosan, 0.5% yeast, and a non-elicitor (as control), while in the sub-main plot, there were two organic fertilizers, water extract of moringa 20 g/m2 dry leaves, 20 g/m2 fulvic acid, and 20 g/m2 (NPK); the latter is a traditional agrochemical. Statistical analysis of all characteristics of production and quality of biomass and biologically active secondary metabolites revealed that the use of organic fertilizers helped in increasing the yield of marjoram, both qualitatively and quantitatively, and significantly outperformed the chemical fertilizer. The experiment enhances the comprehensive and integrated development of marjoram under organic cultivation and achieves a promising alternative to traditional cultivation without the use of microbicides and/or agrochemical pesticides.

Enhancement of Uranium Recycling from Tailings Caused by the Microwave Irradiation-Induced Composite Oxidation of the Fe-Mn Binary System

The extraction of uranium (U)-related minerals from raw ore sands via a leaching procedure would produce enormous amounts of tailings, not only causing radioactivity contamination to surroundings but also wasting the potential U utilization. Effective recycling of U from U tailings is propitious to the current issues in U mining industries. In this study, the influence of the composite oxidation of Fe(III) and Mn(VII) intensified by microwave (MW) irradiation on the acid leaching of U from tailings was comprehensively explored in sequential and coupling systems. The U leaching activities from the tailing specimens were explicitly enhanced by MW irradiation. The composite oxidation caused by Fe(III) and Mn(VII) further facilitated the leaching of U ions from the tailing under MW irradiation in two systems. Maximum leaching efficiencies of 84.61, 80.56, and 92.95% for U ions were achieved in the Fe(III)-, Mn(VII)-, and Fe(III)-Mn(VII)-participated coupling systems, respectively. The inappropriateness of the shrinking core model (SCM) demonstrated by the linear fittings and analysis of variance (ANOVA) for the two systems explained a reverse increase of solid cores in the later stage of leaching experiments. The internal migration of oxidant ions into the particle cores enhanced by MW accelerated the dissolution of Al, Fe, and Mn constituents under acidic conditions, which further strengthened U extraction from tailing specimens.

Asphaltene or Polyvinylchloride Waste Blended with Cement to Produce a Sustainable Material Used in Nuclear Safety

The current research uses sustainable methods to preserve the environment, such as exploiting municipal or industrial waste that may harm the environment. The wreckage of polyvinyl chloride (PVC) pipes and asphaltene are used as additives to cement to improve its mechanical properties, while stabilizing the radioactive waste resulting from the peaceful uses of nuclear materials, or enhancing its radiation shielding efficiency. New composites of Portland cement with ground PVC or asphaltene up to 50% are investigated. Fast neutron removal cross-section (ƩR) and gamma shielding parameters, such as mass attenuation coefficient (MAC), half-value layer (HVL), effective atomic number (Zeff), and exposure build-up factor (EBF) at wide energy range and thickness, are determined. The compressive strength and apparent porosity of the examined composites are examined to test the durability of the prepared composites as stabilizers for radioactive waste. The obtained results show that the bulk density of hardened cementitious composites was slightly increased by increasing the additive amount of PVC or asphaltene. The compressive strength of cement composites reached more than 4.5 MP at 50 wt.% PVC and 8.8 MPa at 50 wt.% asphaltene. These values are significantly higher than those recommended by the US Nuclear Regulatory Commission (3.4 MPa). Additionally, the obtained results demonstrate that although the gamma MAC is slightly decreased by adding asphaltene or PVC, the neutron removal cross-section was highly increased, reaching 171% in the case of 50 wt.% asphaltene and 304% in the case of 50 wt.% PVC. We can conclude that cement composites with PVC or asphaltene have optimized radiation shielding properties and can stabilize radioactive waste.

Chemical toxicity assessment and Physiological investigation in rats exposed to pyrethroid insecticide type 1 and possible mitigation of propolis

The current investigation aims to study the potential protective effects of propolis methanolic extract (100 mg/kg BW) on the systemic toxic effects after dietary exposure concentration (1/100 LD50 for 30 days) of permethrin (PM) administered in experimental rats. In this experiment, we added propolis four weeks after PM -administration to examining the medicinal effects. Therapeutic use of propolis mitigated PM -induced deterioration of liver and kidney functions and myocardial damage measured by cardiac enzymes lactate dehydrogenase (LDH) and creatine kinase MB (CK-MB) in serum. In addition, propolis treatment (prophylactic and therapeutic) prevented PM-induced apoptosis index, including B-cell lymphoma protein 2 (BCL-2)-associated X (BAX) protein activates, and lipid peroxide (LP). The results showed propolis induced a significant decrease in serum levels of thyroid hormones (T3 and T4), proinflammatory cytokines tumor necrosis factor-alpha (TNF-α), interferon-gamma (INF-γ), interleukin one beta (IL-1β), interleukin 12 (IL-12), and interleukin 6 (IL-6). Besides, nuclear factor-kappa B (NF-kB), acetylcholine esterase (AChE), and hematological constituents. Cardiac biomarkers, liver, and kidney functions were substantially lower in propolis treatment. High-performance liquid chromatography (HPLC) and Gas chromatography–mass spectrometry (GC- MS) of the propolis-MeOH extract showed valuable antioxidant phenolics and flavonoids capable of alleviating oxidative stress through the free-radical scavenging efficacy and regulating signaling pathways of proinflammatory cytokines.

Phytoremediation of soil contaminated with nickel, cadmium and cobalt

This pot experiment analyzed the use of Brassica napus, Elymus elongatus and Zea mays in the removal of Cd²⁺ Co²⁺ and Ni²⁺ from the soil. The utility of the plants under study for phytoremediation was analyzed based on the biomass of the aboveground parts and roots and the accumulation of metals, bioaccumulation, bioconcentration and translocation capability in the above-ground parts and roots. The effect of heavy metals on the soil enzyme activity and soil physicochemical properties was also determined. Among the species under study, only E. elongatus was found to be suitable for Cd²⁺ phytoextraction, whereas E. elongatus and Z. mays proved to be suitable for phytostabilisation of Cd²⁺ and Co²⁺ because the criterion of the accumulation of metals in the roots at a sufficient level was fulfilled. The index of bioaccumulation in roots was greater than one. Both plant species met the second condition which determined the utility for phytostabilisation, as since the transport of Cd²⁺ Co²⁺ and Ni²⁺ from the roots to the above-ground parts was limited.