1,721,200 research outputs found
Chemical Affinity Quantum Sieving Effect of Fluorine for Isotopic Separation of Tritium From Radioactive Wastewater
No full text2
Application of Clay Materials for Sorption of Radionuclides from Waste Solutions
No full textThe wide application of nuclear resources in various fields has resulted in the production of radioactive waste, which poses a serious threat to lives and the environment. Nuclear waste contains long-lived radionuclides and, due to its mobility in environments, the proper management of generated waste is necessary. To impede the mobility of radionuclides in environments, various materials have been tested as suitable sorbents under different experimental conditions. In this review, we thoroughly discuss some key and recent contributions to the application of natural clays (NCs) and modified/functionalized clays (MCs) for the sorption of various radionuclides in their cationic and anion forms from (simulated) waste solutions under different experimental conditions. More specifically, we discuss the key developments toward the use of natural clays for the efficient sorption of various radioactive contaminates. Later, this review targets the modification/functionalization of natural clays using various organic moieties to improve their removal capacities for various radionuclides/hazardous ions present in waste solutions. Finally, we summarize the major aspects and highlight the key challenges to be addressed in future studies to further enhance the application of clays and clay-based materials for selective and effective removal of various radionuclides from waste solutions
Efficient radon removal using fluorine-functionalized natural zeolite
No full textRadon (Rn) can easily leak into the environment through groundwater owing to its high water solubility. Therefore, studying the chemical factors influencing the content and removal of Rn from groundwater is crucial for the evaluation and mitigation of its radiological risks to public health. In this study, we conducted a redundancy analysis (RDA) of Rn in groundwater and performed batch sorption experiments for efficient Rn removal from the groundwater collected from Daejeon using natural zeolite (NZ) and fluorine-functionalized natural zeolite (FFNZ) sorbents. The redundancy analysis revealed a positive correlation between the concentrations of Rn and fluorine (F) in groundwater, indicating that F can support the long-term retention of Rn in groundwater. NZ and FFNZ achieved -40% and -70% removal of Rn, respectively, following 24 h of treatment, indicating a significant impact of F (in FFNZ) toward Rn removal from groundwater. Based on the results, Rn is considered to interact with F through the van der Waals force, which limits the volatilization of Rn from the solution. Similarly, the fluorine-functionalized sorbent would interact preferentially with Rn, thereby enhancing its sorption and removal from groundwater.11Nsciescopu
Comparative study of PMS oxidation with Fenton oxidation as an advanced oxidation process for Co-EDTA decomplexation
No full textIn nuclear industry, Co-EDTA complex is generated due to the decontamination activities of nuclear power plants (NPPs). This complex is extremely refractory to the convention methods and can escalate the mobility of Co radionuclide in the environment. Due to its hazardous impact on human and environment, the effective treatments of Co-EDTA complexes are highly recommended. In this study, for the first time, we applied both hydroxyl (OHradical dot) and sulfate radical (SO4radical dot-) based advanced oxidation processes (AOPs) namely Fenton and peroxymonosulfate (PMS) reactions for the Co-EDTA decomplexation. Both reactions exhibited higher Co-EDTA decomplexation at pH = 3, however, the PMS based reaction was found to be superior, which showed highest decomplexation efficiency (without pH adjustment) over Fenton reaction (pH = 1–13). Moreover, PMS based system was found to be more suitable than Fenton reaction, because PMS showed best Co-EDTA decomplexation efficiency without any additional catalyst dosages at the shorter reaction time. XRD data confirmed the presence of both CoO and Co(OH)2 in the precipitates after treatment. The electron spin resonance spectroscopy (ESR) analysis identified OHradical dot and SO4radical dot- in Fenton and PMS system, respectively. From this study, we believe that PMS based reaction is a superior alternative of Fenton reaction for the Co-EDTA decomplexation.11Nsciescopu
Synthesis, Characterization, and Application of Ettringite for Sequestration of 14C from Simulated Waste Solution
No full textCarbon -14 (14C) with a half-life of 5730 years is a great environmental concern for deep geological disposal of irradiated graphite because it is readily mobile in groundwater and atmospheric systems. Herein, we present the synthesis and characterization of Ettringite (a hydrous calcium aluminum sulfate naturally occurring mineral found in cementitious matrices) and its use for effective sequestration of 14C from simulated waste solutions as HCO3- and CO32- at intermediate pH (~ 8.5) and high pH (~11.5) conditions, respectively. Ettringite (powder form) was synthesized via hydrothermal route and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Brunauer – Emmett – Teller (BET) surface area, and Fourier transform infrared (FTIR) analyses. The characterization results confirmed the highly crystalline/uniform/homogeneous ettringite material. In this study, we tested the removal of stable carbon isotope (12C) derived from 100 ppm NaHCO3 aqueous solution (as a surrogate of 14C). A series of tests were performed for effective removal of 14C from simulated waste solution at various experimental conditions (e.g., pH, effect of time, sorbent dose, sorbate dose, etc.). The inorganic carbon concentrations were analyzed using total carbon analyzer prior and after the removal tests. The obtained results revealed ~ 92 % sequestration of 12C (either HCO3- or CO32- species) from simulated waste solution using ettringite in 48-hours (h) and 8h contact times at intermediate pH (~8.5) and high pH (~11.50), respectively. We observed a considerable phase alteration of ettringite into calcite at intermediate pH (~8.5) 12C removal tests, which shows the instability of ettringite structure at low or intermediate pH condition. However, the ettringite structure was quite stable at high pH (~ 11.50) 12C removal experiments, as the XRD analysis data of ettringite powder confirmed the presence of all major ettringite peaks after the sequestration experiments. Additionally, the applicability of pseudo second order kinetics was determined for the removal of 12C onto ettringite.
Some additional experiments and further characterizations of ettringite powder after 12C removal experiments are underway to interpret the interaction mechanism of HCO3- and CO32- with ettringite at the defined experimental conditions. Moreover, our work will further explore the application of synthesized ettringite for sequestration of other hazardous anions, including, IO3-, ReO4-/TcO4-, and PO43- under different physicochemical conditions. We believe that this study would facilitate us to predict the affinity of ettringite mineral towards various hazardous anions and prevent their mobility in environment.1
sj-pdf-1-pie-10.1177_09544089221128768 - Supplemental material for Analysis of Arrhenius activation energy on magnetohydrodynamic gyrotactic microorganism flow through porous medium over an inclined stretching sheet with thermophoresis and Brownian motion
No full textSupplemental material, sj-pdf-1-pie-10.1177_09544089221128768 for Analysis of Arrhenius activation energy
on magnetohydrodynamic gyrotactic microorganism flow through porous medium over an inclined stretching sheet with thermophoresis and Brownian motion by Bhupendra Kumar Sharma, Umesh Khanduri, Nidhish K Mishra and Ali J Chamkha in Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering</p
Inorganic Waste Forms for Efficient Immobilization of Radionuclides
No full textThe immobilization of long-lived radionuclide wastes generated from nuclear power plants (NPPs) during NPP operation, fuel reprocessing, and decommissioning of nuclear reactors is of great environmental concern. Designing suitable matrices with high durability, stability, and resistivity to various physical and chemical conditions (temperature, pressure, radiation, acidity/alkalinity, etc.) are required for the safe disposal and effective immobilization of radioactive wastes. In this review, we highlight and discuss the key developments in the design and applications of major inorganic waste forms for radioactive waste immobilization. Specifically, we review (i) glasses (borosilicates, phosphates, and sintered glasses), (ii) cements (Portland cement, cast stone/saltstone, hydroceramics, and geopolymer), (iii) synrocs (hollandite, zirconolite, and perovskite), and (iv) ceramics (titanates, sodalite, apatite, monazites, and goethite/magnetite). Additionally, we present future challenges that should be addressed during the design and selection of suitable waste forms for the immobilization of radionuclides. We believe that this paper can deepen our understanding of various waste forms and their roles in radioactive waste immobilization.11Nothe
Fluorine-Functionalized Mesoporous Silica for Selective Removal of Tritium From Nuclear Waste Water
No full text2
- …
