Investigation of Adsorption Mechanism of Layered Double Hydroxides and Their Composites on Radioactive Uranium:A Review

Abstract

With the rapid development of nuclear industry, nuclear energy, as a kind of low-carbon energy, has been widely used in the world. However, in the development and application of nuclear energy, a large amount of radionuclides, especially the radioactive uranium, have been inevitably discharged into the environment, causing serious environmental pollution and having great harm to human health. Layered double hydroxides (LDHs) have become the excellent adsorbents in environmental pollution treatments due to easy preparation, large specific surface area, the unique nanostructure and excellent ion exchange capacity. Hence, the preparation of layered double hydroxides and their composites for the efficient removal of radioactive uranium is one of the hot issues in the field of environmental science, which include coprecipitation, ion exchange, hydrothermal method, the urea hydrolysis method, aerogel, microwave-crystallization and separate nucleation/crystallization isolation method. Besides the aforementioned methods, other reported synthesis methods of LDHs include the secondary intercalation method (an intercalation method involving dissolution and the re-coprecipitation method), reconstruction method based on the "memory effect", N 2 protection synthesis, mechanochemical synthesis, surface synthesis, template synthesis, and others. The modification methods of layered double hydroxides can be divided into calcination, intercalation and compounding method, which significantly increase the active sites and further improve the adsorption performance of the materials to radioactive uranium. In addition, the adsorption mechanism has been thoroughly investigated with spectroscopic analysis techniques such as Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Extended X-ray absorption fine structure (EXAFS). In conclusion, the review briefly discuss the application prospects of layered double hydroxides and their composites in the treatment of water pollution, which provide definitive reference values for the further research and practical application of environmental management in the future.

Sorption Behaviors and Mechanismsof Eu(III) on Rice Straw-derived Biochar

“…And to keep complete carbonization, the pyrolysis time was set at 4 h. Eu(III) stock solution was prepared by dissolving, evaporating, and re-dissolving Eu 2 O 3 in 1.0 mmol/L HClO 4 . Humic substances，i.e., humic acid (HA) and fluvic acid (FA), extracted from the soil in Hua-Jia county (Gansu province, China), were adequately studied previously and proved to have strong effects on interactions between adsorbate and adsorbent [3,28] . All chemicals employed in this experiment were purchased in analytical purity and used without any purification.…”

“…All properties of adsorbates, adsorbents, and aqueous solutions determine the sorption behavior of heavy metals on adsorbents. Effects of many environmental factors such as pH, ionic strength, humic substances, and temperature on Eu(III) sorption onto various adsorbents have been proved to be evident [1][2][3][4][5][16][17][18][19]26] . It indicates that environmental factors of solid-liquid interface mediate the Eu(III) sorption process.…”

Role of Synergistic Effect in Oxygen Evolution Reaction over Layered Double Hydroxide

“…水滑石类材料(LDHs)是由带正电荷的主体层板和 层间阴离子通过非共价键的相互作用组装而成的化合 物, 具有主体层板的金属离子以及层间阴离子种类和组 成可调变性、合成方法简单、价格低廉等优点 [1][2][3] , 因而 被广泛应用于催化等领域 [4][5][6] . 已有研究表明, 含有过渡 金属(如 Ni, Co, Fe, Mn 等)元素的 LDH 具有良好的析氧 反应(OER)催化活性 [7] .…”

Magnetic-dictyophora indusiata derived biochar composite for efficient removal of U(VI) and mechanism investigation

“…低并且无二次污染等诸多优势而被广泛选择, 包括物 理吸附和化学吸附两种方式 [8] . 常见的吸附材料如黏 土矿物 [9] 、氧化石墨烯材料 [10] 、有机金属框架材料 (metal-organic frameworks, MOFs) [11] 等, 但大多受限于…”