Experimental and theoretical studies of spherical hydroxylamine hydrochloride intercalated molybdenum disulfide for the removal of U(VI), Eu(III), and Cr(VI)

The current environmental problem is the coexistence of multiple pollutants rather than a single pollutant. In this study, U(VI), Eu(III), and Cr(VI) are selected as representatives of the actinides, lanthanide elements, and heavy metal elements for removal study. The hydroxylamine hydrochloride intercalated molybdenum disulfide (HAH/MoS2) was prepared to remove these contaminants. The insertion of hydroxylamine hydrochloride increased layer spacing, which was conducive to the pollutant molecules entering the molybdenum disulfide layer. HAH/MoS2 revealed a spherical shape with a rough surface and relatively high anti-interference. The maximum adsorption capacities of HAH/MoS2 for U(VI), Eu(III), and Cr(VI) reached 104.9 mg/g, 72.9 mg/g, and 81.4 mg/g, respectively. The adsorption mechanism of U(VI) was interlayer adsorption at pH < 6.2 and surface complexation at pH > 6.2. Similarly, the removal of Eu(III) was interlayer adsorption at pH < 5.0, interlayer adsorption and surface complexation at pH 5.0-7.7, and forming precipitation Eu(OH)3(s) at pH > 7.7. The removal of Cr(VI) depended on surface complexation at pH < 4.0 and interlayer adsorption at pH > 4.0. These ions were more likely to be adsorbed between layers instead of at the surface. Compared to U(VI) and Cr(VI), Eu(III) was more easily adsorbed at the interlamination of HAH/MoS2. From the point of view of charge transfer, U(VI) and Eu(III) tended to give away electrons, and Cr(VI) tended to gain electrons in the removal process. This work can offer a new perspective for the design and application of two-dimensional materials for multiple pollutants removal.

Selective biosorption of Li+ in aqueous solution by lithium ion-imprinted material on the surface of chitosan/attapulgite

The extraction of Li+ from liquid lithium resources is a pivotal focus of current research endeavors. Attapulgite (ATP), characterized by its distinctive layered structure and inherent ion exchange properties, emerges as an exceptional material for fabricating lithium-ion sieve. Ion-imprinted chitosan/ATP composite materials are successfully synthesized, demonstrating efficacy in selectively absorbing Li+. The results emphasize the rich functional groups present in H-CTP-2, enhancing its absorbability and selectivity, with an adsorption capacity of 37.56 mg•g-1. The adsorption conforms to the Langmuir and pseudo-second-order kinetic model. Li+ coordination involves amino and hydroxyl group, indicating a chemisorption process. Furthermore, the substantial pore structure and significant specific surface area of ATP significantly promote Li+ adsorption, suggesting its participation not only in chemisorption but also in physical adsorption. The fabricated ion-imprinted materials boast substantial adsorption capacity, exceptional selectivity, and rapid kinetics, highlighting their potential for effectively separating Li+ from aqueous solution.

Synthesis of potential Ca-Mg-Al layered double hydroxides coated graphene oxide composites for simultaneous uptake of europium and fulvic acid from wastewater systems

High background electrolyte and natural organic matter are favorable to migration of hazardous radionuclides in geochemical repository. Herein, Ca-Mg-Al layered double hydroxide coated onto graphene oxide (Ca-Mg-Al LDH/GO) composites were successfully synthesized, characterized and adopted to decontaminate Eu(III) and fulvic acid (FA) under diverse experimental conditions. Diverse concentration gradients and different addition sequences on Eu(III) and FA were also obtained, which revealed different interaction mechanisms. The experimental results displayed that the coexistence of FA and Eu(III) respectively promoted adsorption performance of Eu(III) and FA under the ternary systems. The acquired Ca-Mg-Al LDH/GO composites were adopted to remove Eu(III) and FA, which further illustrated excellent chemo-physical stability and adsorption capacity of 1.12 × 10^-3 mol/g and 3.54 × 10^-4 mol/g, respectively. The remarkable adsorption performances of Ca-Mg-Al LDH/GO were confirmed through kinetic procedures and depending-temperature isotherms, illustrating that the kinetics processes were simulated using pseudo-second-order pattern, and the adsorption isotherms were splendidly simulated using Langmuir pattern. XPS spectrum analysis revealed that these containing oxygen groups took significant part in the restricting of Eu(III) and FA onto the surfaces of Ca-Mg-Al LDH/GO composites. In view of experimental results, the Ca-Mg-Al LDH/GO composites can be as potential adsorbents with availably recycled reusability for the decontamination of Eu(III) and FA from nuclear fuel partition or nuclear wastewater systems.

Transforming lanthanide and actinide chemistry with nanoparticles

Lanthanides and actinides are used in a wide variety of applications, from energy production to life sciences. To address toxicity issues due to the chemical, and often radiological, properties of these elements, methods to quantify and recover them from industrial waste are necessary. When used in biomedicine, lanthanides and actinides are incorporated in compounds that show promising therapeutic and/or bioimaging properties, but lack robust strategies to target cancer and other pathologies. Furthermore, current decorporation protocols to respond to accidental actinide exposure rely on intravenous injections of soluble chelating agents, which are inefficient for treatment of inhaled radionuclides trapped in lungs. In recent years, nanoparticles have emerged as powerful tools in both industry and clinical settings. Because some inorganic nanoparticles are sensitive to external stimuli, such as light and magnetic fields, they can be used as building blocks for sensitive bioassays and separation techniques. In addition, nanoparticles can be functionalized with multiple ligands and act as carriers for selective delivery of therapeutic and contrast agents. This review summarizes and discusses recent progress on the use of nanoparticles in lanthanide and actinide chemistry. We examine different types of nanoparticles based on composition, functionalization, and properties, and we critically analyze their performance in a comparative mode. Our focus is two-pronged, including the nanoparticles free of lanthanides and actinides that are used for the detection, separation, or decorporation of f-block elements, as well as the nanoparticles that enhance the inherent properties of lanthanides and actinides for therapeutics, imaging and catalysis.

Magnetite-Coated Boron Nitride Nanosheets for the Removal of Arsenic(V) from Water

It is widely known that the existence of arsenic (As) in water negatively affects humans and the environment. We report the synthesis, characterization, and application of boron nitride nanosheets (BNNSs) and Fe₃O₄-functionalized BNNS (BNNS-Fe₃O₄) nanocomposite for removal of As(V) ions from aqueous systems. The morphology, surface properties, and compositions of synthesized nanomaterials were examined using scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, surface area analysis, zero-point charge, and magnetic moment determination. The BNNS-Fe₃O₄ nanocomposites have a specific surface area of 119 m² g^-1 and a high saturation magnetization of 49.19 emu g^-1. Due to this strong magnetic property at room temperature, BNNS-Fe₃O₄ can be easily separated in solution by applying an external magnetic field. From the activation energies, it was found that the adsorption of As(V) ions on BNNSs and BNNS-Fe₃O₄ was due to physical and chemical adsorption, respectively. The maximum adsorption capacity of BNNS-Fe₃O₄ nanocomposite for As(V) ions has been found to be 26.3 mg g^-1, which is 5 times higher than that of unmodified BNNSs (5.3 mg g^-1). This closely matches density functional theory simulations, where it is found that binding energies between BNNS-Fe₃O₄ nanocomposite and As(OH)₅ are 5 times higher than those between BNNSs and As(OH)₅, implying 5 times higher adsorption capacity of BNNS-Fe₃O₄ nanocomposite than unmodified BNNSs. More importantly, it was observed that the synthesized BNNS-Fe₃O₄ nanocomposite could reduce As(V) ion concentration from 856 ppb in a solution to below 10 ppb (>98.83% removal), which is the permissible limit according to World Health Organization recommendations. Finally, the synthesized adsorbent showed both separation and regeneration properties. These findings demonstrate the potential of BNNS-Fe₃O₄ nanocomposite for commercial application in separation of As(V) ions from potable and waste water streams.