Efficacy of a Graphene Oxide/Chitosan Sponge for Removal of Radioactive Iodine-131 from Aqueous Solutions

Advanced technologies in water treatment: Chitosan and its modifications as effective agents in the adsorption of contaminants

Chitosan, derived from the abundant biopolymer chitin, has emerged as a promising option for water treatment due to its intrinsic bioavailability. This review emphasizes the notable characteristics of chitosan, which allow for various modifications, expanding its applications. The polymer's effectiveness in adsorbing contaminants, particularly in advanced water treatment technologies, is highlighted. The review underscores the potential of chitosan-based hybrid materials, including nanocomposites, hydrogels, membranes, films, sponges, nanoparticles, microspheres, and flakes, as innovative alternatives to traditional chemical-based adsorbents. The advantages of using these materials in wastewater treatment, especially in removing heavy metals, dyes, and emerging compounds, are explored. The study delves into the mechanisms involved in wastewater treatment with chitosan, emphasizing the interactions between the polymer and various contaminants. Additionally, the application of chitosan as a contaminant removal agent in a post-pandemic context is addressed, considering the challenges related to waste management and environmental preservation. The analysis highlights the potential contribution of chitosan in mitigating environmental impacts post-pandemic, offering practical solutions for treating contaminated effluents and promoting sustainability. The study addresses current obstacles and prospects for chitosan-based wastewater treatment, emphasizing its promising role in sustainable water management.

Mn3O4@polyaniline nanocomposite with multiple active sites to capture uranium(VI) and iodide: synthesis, performance, and mechanism

A major challenge for radioactive wastewater treatment and associated environmental remediation is how to simultaneously remove cationic and anionic radionuclides. Herein, a series of Mn₃O₄@polyaniline (Mn₃O₄@PANI) nanocomposites were successfully prepared and used to remove U(VI) and I^- from aqueous solution, two highly concomitant species in nuclear pollution settings. Batch adsorption experiments reveal that the component Mn₃O₄ is predominantly responsible for U(VI) removal, but PANI for I^-. The nanocomposite with 24.2 wt% Mn₃O₄ possesses high removal percentages (> 85%) either for U(VI) or I^- over a wide pH range, fast removal kinetics, and excellent adsorption selectivity at high concentrations of competing ions. Benefiting from the contributions of the two components and the high adsorption affinities, the nanocomposite achieves the simultaneous removal to coexisting U(VI) and I^-, with a maximum adsorption capacity 102.6 mg/g for U(VI) and 126.1 mg/g for I^-. X-ray photoelectron spectroscopy (XPS) results reveal that the U(VI) adsorption occurs via coordination bonding with Mn-O, -NH- , and =N- groups in the nanocomposite, whereas I^- adsorption proceeds mainly through I anionic species exchange with Cl^- and interactions with π-bonds in PANI, as well as the electrostatic attraction onto Mn₃O₄. Considering the excellent performance and multiple active sites, the Mn₃O₄@PANI nanocomposite is promising to remove practical radioactive U(VI) and I^-.

A Critical Review of the Removal of Radionuclides from Wastewater Employing Activated Carbon as an Adsorbent

Radionuclide-contaminated water is carcinogenic and poses numerous severe health risks and environmental dangers. The activated carbon (AC)-based adsorption technique has great potential for treating radionuclide-contaminated water due to its simple design, high efficiency, wide pH range, quickness, low cost and environmental friendliness. This critical review first provides a brief overview of the concerned radionuclides with their associated health hazards as well as different removal techniques and their efficacy of removing them. Following this overview, this study summarizes the surface characteristics and adsorption capabilities of AC derived from different biomass precursors. It compares the adsorption performance of AC to other adsorbents, such as zeolite, graphene, carbon nano-tubes and metal-organic frameworks. Furthermore, this study highlights the different factors that influence the physical characteristics of AC and adsorption capacity, including contact time, solution pH, initial concentration of radionuclides, the initial dosage of the adsorbent, and adsorption temperature. The theoretical models of adsorption isotherm and kinetics, along with their fitting parameter values for AC/radionuclide pairs, are also reviewed. Finally, the modification procedures of pristine AC, factors determining AC characteristics and the impact of modifying agents on the adsorption ability of AC are elucidated in this study; therefore, further research and development can be promoted for designing a highly efficient and practical adsorption-based radionuclide removal system.

Fluorine-18 Fluorodeoxyglucose Isolation Using Graphene Oxide for Alternative Radiopharmaceutical Spillage Decontamination in PET Scan

Radiopharmaceuticals (RPC) used for diagnostic and therapeutic purposes in nuclear medicine may contaminate surface areas due to spillage during its preparation or accident during RPC transfer from laboratory to the treatment room. Fluorine-18 Fluorodeoxyglucose (18F-FDG) is the most common RPC for positron emission tomography (PET) scan in nuclear medicine due to its ideal annihilation converted energy at 511 keV and short half-life at 109.8 min. Ineffective medical waste management of 18F-FDG may pose a risk to the environment or cause unnecessary radiation doses to the personnel and public. Depending on the incident rate of these events, simple decontamination methods such as the use of chemicals and swabs might not be cost-effective and sustainable in the environment. This study aims to propose an alternative method to decontaminate 18F-FDG by using graphene oxide (GO). GO was synthesised using the Hummers method while the physical morphology was analysed using a field emission scanning electron microscope (FESEM). 18F-FDG adsorption efficiency rate using GO nanolayers was analysed based on the kinetic study of the GO:18F-FDG mixtures. The chemical adsorbability of the material was analysed via UV–vis spectrophotometer to interlink the microstructures of GO with the sorption affinity interaction. Resultantly, the adsorption rate was effective at a slow decay rate and the optical adsorption of GO with 18F-FDG was dominated by the π → π* plasmon peak, which was near 230 nm. By elucidating the underlining GO special features, an alternative technique to isolate 18F-FDG for the decontamination process was successfully proven.

Experimental Investigations of AlMg3 Components with Polyurethane and Graphene Oxide Nanosheets Composite Coatings, after Accelerated UV-Aging

The use of graphene (Gr) and its derivates graphene oxide (GO) showed that these materials are good candidates to enhance the properties of polyurethane (PU) coatings, especially the anticorrosion ones since graphene absorbs most of the light and provides hydrophobicity for repelling water. An important aspect of these multifunctional materials is that all these improvements can be realized even at very low filler loadings in the polymer matrix. In this work, an ultrasound cavitation technique was used for the proper dispersion of GO nanosheets (GON) in polyurethane (PU) resin to obtain a composite coating to protect the AlMg3 substrate. The addition of GON considerably improved the physical properties of coatings, as demonstrated by electrochemical impedance spectroscopy (EIS) analysis, promising improved anticorrosion performance after accelerated UV-ageing. Computational methods and Differential Scanning Calorimetry (DSC) measurements showed that GON facilitates the formation of additional bonds and stabilizes the PU structures during the ultraviolet (UV) exposure and aggressive attack of corrosive species. Limiting oxygen index (LOI) data reveal a slow burning behaviour of PU-GON coatings during UV exposure, which is better than PU alone.