Removal Of Uranium Research Articles

Photo‐enhanced uranium recovery from spent fuel reprocessing wastewater via S‐scheme 2D/0D C3N5/Fe2O3 heterojunctions

AbstractRe‐extracting environmentally transportable hexavalent uranium from wastewater produced by spent fuel reprocessing using the photocatalytic technology is a crucial strategy to avoid uranium pollution and recover nuclear fuel strategic resources. Here, we have designed S‐scheme 2D/0D C3N5/Fe2O3 heterojunction photocatalysts based on the built‐in electric field and the energy band bending theory, and have further revealed the immobilization process of hexavalent uranium conversion into relatively insoluble tetravalent uranium in terms of thermodynamics and kinetics. According to the results, the hexavalent uranium removal and recovery ratios in wastewater are as high as 93.38% and 83.58%, respectively. Besides, C3N5/Fe2O3 heterojunctions also exhibit satisfactory catalytic activity and selectivity even in the presence of excessive impurity cations (including Na+, K+, Ca2+, Mg2+, Sr2+, and Eu3+) or various organics (such as xylene, tributylphosphate, pyridine, tannic acid, citric acid, and oxalic acid). It is believed that this work can provide a potential opportunity for S‐scheme heterojunction photocatalysts to re‐enrich uranium from spent fuel wastewater.

Spatially confined coordination platform in covalent organic framework for selective uranium adsorption from aqueous solutions

The use of covalent organic frameworks (COFs) to remove uranium from nuclear wastewater, especially capture uranium by well-defined nanopores and customizable groups, is highly desired. The development of an ideal binding site with optimal balance between adsorption capacity and selectivity has remained an attractive challenge. Herein, a staggered stacking self-assembly approach was adapted to control the pore size and confine space of dioxin-linked COF-316 with modified functional groups to achieve higher capture efficiency. EXAFS analysis suggested that COF-316-COOH and COF-316-AO both have high affinities toward U(VI) owing to inner-sphere surface complexation by two or three atoms, DFT calculations further revealed that the uranyl cation was coordinated by = NOH or –COOH groups from two adjacent COF layers. The synergistic coordination in multi-confined interlaminar position provides an ideal spatial coordination platform for uranium, and the merits of capacity, selectivity and stability underscore the potential application of COF-316-AO for efficient uranium removal.

A sodium alginate gel bead adsorbent doping with amidoxime-modified hydroxyapatite for the efficient adsorption of uranium

In this work, the modified‑sodium alginate gel beads were prepared by sol-gel method. Due to the presence of water channels in the sodium alginate gel bead, amidoxime groups and PO43− were exposed to the surface of the adsorbent to the maximum extent, resulting in the excellent adsorption capacity of modified‑sodium alginate gel beads. The introduction of amidoxime-modified hydroxyapatite significantly improved the adsorption capacity and the adsorption rate of the gel beads. The adsorption capacity increased from 308.7 to 466.0 mg/g and the adsorption equilibrium time was shortened from 300 min to 120 min. The modified‑sodium alginate gel bead possessed the advantages of short adsorption time, high adsorption efficiency and large adsorption capacity, which could be regarded as a potential adsorbent for uranium. Moreover, the uranium removal ability on the modified gel beads was mainly attributed to the Coulomb force between PO43− and uranium and the complexation between uranium and amidoxime groups. In summary, this work would provide a new idea for the modification and application of sodium alginate-based materials.

Study on the remediation of uranium-contaminated soils by compound leaching: Screening of leaching agents and a pilot-scale application

To solve the problem of soil environmental pollution resulting from uranium mine development and production, a soil slurry reactor was used to evaluate the use of chemical leaching to remediate uranium-contaminated soils and to analyze possible uranium removal mechanisms through laboratory-scale trials and pilot-scale trials. A laboratory-scale trial comparing different reagents and operating methods revealed that the removal of total uranium from contaminated soil could reach 91.18% under optimal conditions when FeCl3, OA, NaClO2, and HEDP were used as eluents.Based on the optimal ratio and operating conditions determined from laboratory-scale trials, a pilot-scale trial was conducted around a uranium mining area: soil leaching remediation was conducted in two 3 m3 soil-slurry reactors to verify the practicality of the leaching technology and examine the functionality of the remediated soil. The experimental results showed that the rate of uranium removal from contaminated soil by the chemical leaching method was greater than 80%. FTIR, XRF and enzyme activity analysis proved that remediation restored the original soil function and reduced the ecological risk, indicating that the chemical leaching technology was environmentally friendly and economical. These findings provide insight to guide the future assessment and remediation practices of uranium-contaminated sites.

Adsorptive removal of uranium from aqueous solution using magnetic hydroxyapatite

High efficiency and easy separation adsorbents are important for the treatment of uranium-containing wastewater, but still face challenges. In this paper, a new effective adsorbent for uranium removal from wastewater, i.e., PEG-β-CD-nHA@Fe3O4 composite, was synthesized by hydrothermal reaction using iron doping and in-situ co-precipitation method, in which polyethylene glycol (PEG) and beta-cyclodextrin (β-CD) were used as double templates to mediate the synthesis process. The results showed that the morphology and magnetic property of the composite were significantly improved. The adsorption capacity reached 928.46 mg/g, and the composite could be quickly magnetically separated after U(Ⅵ) adsorption. U(Ⅵ) adsorption performance was obviously affected by adsorbent dosage, pH, contact time and U(VI) concentration. Pseudo-second-order (PSO) and Sips models could accurately fit adsorption experimental data, indicating that it was chemisorption, in which –OH and PO43- played an important role. U(VI) ions were adsorbed and fixed through complexation, precipitation and ion exchange. The results indicated that PEG-β-CD-nHA@Fe3O4 composite was a green, efficient and easily separated adsorbent for U(VI) removal.

Study on uranium ion adsorption property of porous glass modified with amidoxime group.

In this paper, we prepared three types of porous glasses (PGs) with specific surface areas of 311.60 m2/g, 277.60 m2/g, and 231.38 m2/g, respectively, via borosilicate glass phase separation. These glasses were further modified with amidoxime groups (AO) using the hydroxylamine method, yielding adsorbents named 1.5-PG-AO, 2-PG-AO, and 3-PG-AO. The adsorption performance of these adsorbents under various conditions was investigated, including sorption kinetics and adsorption mechanisms. The results reveal that the number of micropores and specific surface area of PG are significantly reduced after AO modification. All three adsorbents exhibit similar adsorption capabilities. Particularly, pH has a pronounced effect on U (VI) adsorption of PG-AO, with a maximum value at pH = 4.5. Equilibrium adsorption is achieved within 2h, with a maximum adsorption capacity of 129mg/g. Notably, a uranium removal rate of 99.94% is attained. Furthermore, the adsorbents show high selectivity in uranium solutions containing Na+ or K+. Moreover, the adsorbents demonstrate exceptional regeneration ability, with the removal rate remaining above 80% even after undergoing five adsorption-desorption cycles. The adsorption reaction of uranium on PG-AO involves a combination of multiple processes, with monolayer chemisorption being the dominant mechanism. Both the complex adsorption of AO and the ion exchange and physical adsorption of PG contribute to the adsorption of uranyl ions on the PG-AO adsorbents.

Dipole Moment and Built-In Polarization Electric Field Induced by Oxygen Vacancies in BiOX for Boosting Piezoelectric-Photocatalytic Removal of Uranium(VI).

Piezoelectric-photocatalysis is distinguished by its piezoelectricity as an external force that induces deformation within the catalyst to engender a polarized electric field compared to conventional photocatalysis. Herein, the piezoelectric photocatalyst BiOBr has been expertly synthesized via a plasma process and applied for piezoelectric-photocatalysis removal of uranium(VI) for the first time. The abundant surface oxygen vacancies (OVs) could induce a dipole moment and built-in electric field, which endows BiOBr with excellent separation and transport efficiency of photogenerated charges to actuate more charges to participate in the piezoelectric-photocatalytic reduction process. Consequently, under visible light and ultrasound (150 W and 40 kHz), the removal rate constant of OVs-BiOBr-30 (0.0306 min-1) was 2.4, 30.6, and 6 times higher than those of BiOBr (0.01273 min-1), ultrasound, or photocatalysis, respectively. The piezoelectric-photocatalytic synergy is also universal for BiOX (X = Cl, Br, or I) to accelerate the reduction rate of uranium(VI). This work highlights the role of piezoelectric-photocatalysis in the treatment of uranium-containing wastewater, which is of great significance for resource conservation and environmental remediation.

Extraction of Uranium by a Cheap Phosphite-Derived Polymer under Light Condition.

Uranium, as the main fuel of today's nuclear energy, is crucial to the development of nuclear energy. Therefore, the development of low-cost and powerful adsorbents is very important for the removal or recovery of uranium from uranium-containing solutions. Herein, we report the synthesis of a cheap phosphite-derived polymer for such use. Under visible-light irradiation, this phosphite-derived polymer was found to enable selective adsorption of uranium with an adsorption capacity as high as 1030 mg/g, suggesting its great potential in handling nuclear waste.

Innovative Conversion Strategy for Wastewater with One‐Pot Uranium Extraction and Valuable Chemical Production by a Smart COF Photocatalyst

AbstractEnvironmental protection and resource reclamation make the extraction of uranium from uranium‐containing wastewater be a key role in the nuclear chemistry and industry. Although previous studies have revealed several effective methods and materials for such use, however, few studies are concerned about the wastewater discharge issues. In fact, the direct discharge of treated wastewater into the environment is still not a green way. Here, an innovative conversion approach is shown, which can simultaneously achieve the uranium extraction and conversion of wastewater to valuable chemical. This concept is implemented by an azobenzene‐pendent covalent organic framework, showing smart trans‐to‐cis photoresponsive properties in both space and electronic structure and consequently, largely enhanced extraction and conversion efficiency under UV irradiation, relative to visible light irradiation. In real wastewater, the material is found to give selective and 100% uranium extraction and H2O2 generation (1872.3 µmol g−1 h−1). The mechanism is due to a unique photocatalysis coupling between the uranium reduction reaction (URR), aiming at uranium recovery or removal, and the water oxidation reaction (WOR), targeting the conversion of wastewater into a valuable chemical of H2O2.

Dithiocarbamate functionalised crosslinked polyacrylamide for separation and pre-concentration of uranium (VI) ions from sulphate medium

ABSTRACT This article introduces a novel approach for extracting and concentrating uranium (VI) ions from water-based solutions using two dithiocarbamate functionalised cross-linked polyacrylamide adsorbents, CPAAm-DETA-CS2 and CPAAm-EDA-CS2. The adsorbents were synthesised and characterised through techniques like Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and elemental analysis. The efficacy of these adsorbents in removing U(VI) species from solution matrices was systematically investigated, yielding maximum adsorption capacities of approximately 57.8 mg/g and 60.2 mg/g for CPAAm-EDA-CS2 and CPAAm-DETA-CS2, respectively. The optimised operational parameters encompassed a solution pH of 4.0, a contact period of 60 minutes, and an adsorbent dosage of 1.7 g/L, all conducted at ambient temperature. The adsorption adhered to the Langmuir isotherm and pseudo-second order kinetics, with a spontaneous and exothermic nature. Notably, the adsorbents displayed potential for regeneration and reuse. CPAAm-DETA-CS2 sorbent which exhibits the highest sorption capacity was applied successfully for the removal of uranium(VI) removal from sulphate leach liquor of Sella uranium ore. The adsorption capacity of the prepared sorbent was ≈ 45.3 mg/g. These aforementioned findings underscore the viability of a sustainable approach for uranium extraction, highlighting the notable importance of dithiocarbamate functionalised cross-linked polyacrylamide as a proficient adsorbent within the realm of environmental and industrial uranium separation processes.

Enhanced uranium removal from aqueous solution by core–shell Fe0@Fe3O4: Insight into the synergistic effect of Fe0 and Fe3O4

In this study, Fe0@Fe3O4 was synthesized and used to remove U(VI) from groundwater. Different experimental conditions and cycling experiments were used to investigate the performance of Fe0@Fe3O4 in the U(VI) removal, and the XRD, TEM, XPS and XANES techniques were employed to characterize the Fe0@Fe3O4. The results showed that the U(VI) removal efficiency of Fe0@Fe3O4 was 48.5 mg/g that was higher than the sum of removal efficiency of Fe0 and Fe3O4. The uranium on the surface of Fe0@Fe3O4 mainly existed as U(IV), followed by U(VI) and U(V). The Fe0 content decreased after reaction, while the Fe3O4 content increased. Based on the results of experiments and characterization, the enhanced removal efficiency of Fe0@Fe3O4 was attributed to the synergistic effect of Fe0 and Fe3O4 in which Fe3O4 accelerated the Fe0 corrosion that promoted the progressively formation of Fe(II) that promoted the reduction of adsorbed U(VI) to U(IV) and incorporated U(VI) to U(V). The performance of Fe0@Fe3O4 at near-neutrality condition was better than at acidic and alkalic conditions. The chloride ions, sulfate ions and nitrate ions showed minor effect on the Fe0@Fe3O4 performance, while carbonate ions exhibited significant inhibition. The metal cations showed different effect on the Fe0@Fe3O4 performance. The removal efficiency of Fe0@Fe3O4 decreased with the number of cycling experiment. Ionizing radiation could regenerate the used Fe0@Fe3O4. This study provides insight into the U(VI) removal by Fe0@Fe3O4 in aqueous solution.

Study on the mechanism and stability of microbially induced struvite precipitation (MISP) for enhanced immobilization of uranium

The microbial induced carbonate precipitation (MICP) technique has been shown to immobilize a wide range of heavy metals. However, the MICP process for removing uranium-dominated composite heavy metals ignores the formation of substances such as uranyl carbonate, which can easily lead to uranium migration. Furthermore, the by-product ammonia is one of the bottlenecks limiting the application of MICP. In this work, the microbially induced struvite precipitation (MISP) method was used to enhance U immobilization while reducing by-product contamination. The results showed that the optimal uranium removal rate of the MISP process was increased by 82.98% compared to the MICP. Characterization results confirmed the co-precipitation of U with NH4+ in the form of uramphite and struvite, while the participation of U changed the mineral crystal shape. Stability experiments showed that the maximum release of U from struvite was only 1.27%, which is much lower than the minimum release of U from CaCO3. As a result, the MISP process both enhanced uranium immobilization efficiency, decreased the risk of uranium migration-release, and reduced the environmental impact of the by-product ammonia. These results provided a new perspective for studying U contamination remediation and its co-precipitation behavior in microbial mineralization.

Humic acid-nanoceria composite as a sustainable adsorbent for simultaneous removal of uranium(VI), chromium(VI), and fluoride ions from aqueous solutions.

In this article, the multifunctional behavior of novel, efficient, and cost-effective humic acid-coated nanoceria (HA@CeO2 NPs) was utilized for the sorptive removal of U(VI), Cr(VI), and F- ions at different conditions. The production cost of HA@CeO2 was $19.28/kg and was well characterized by DLS, FESEM, HRTEM, FTIR, XRD, XPS, and TGA. Batch adsorption study for U(VI) (at pH ~ 8), Cr(VI) (at pH ~ 1), and F- (at pH ~ 2) revealed that the maximum percentage of sorption was > 80% for all the cases. From the contact time experiment, it was concluded that pseudo-second-order kinetics followed, and hence, the process should be a chemisorption. The adsorption study revealed that U(VI) and Cr(VI) followed the Freundlich isotherm, whereas F- followed the Langmuir isotherm. Maximum adsorption capacity for F- was 96mgg-1. Experiments in real water suggest that adsorption is decreased in Kaljani River water (~ 12% for Cr(VI) and ~ 11% for F-) and Kochbihar Lake water (25.04% for Cr(VI) and 20.5% for F-) because of competing ion effect. Mechanism was well established by the kinetic study as well as XPS analysis. Because of high adsorption efficiency, HA@CeO2 NPs can be used for the removal of other harmful water contaminants to make healthy aquatic life as well as purified drinking water.

Bioinspired electrostatic layer-by-layer assembly membranes constructed based on mild strategy for uranium extraction from seawater

Developing simple and efficient new strategies for uranium extraction from seawater (UES) is crucial for addressing the energy crisis. Here, we proposed a mild strategy to prepare a layer-by-layer assembly membrane (LAM) by polydopamine (PDA) and polyethyleneimine (PEI) co-deposition coupled with polyethyleneimine/phytic acid self-assembly for efficient uranium extraction. By regulating the number of self-assemblies, the performance of the membrane could be easily adjusted. The functional coating’s rich active groups (–NH2, -PO43-, –OH) provided a good adsorption performance for the modified membrane, with a static adsorption capacity of 142.25 mg·g−1. Meanwhile, it possessed excellent dynamic removal rate, which could achieve over 90 % uranium removal within 90 min. The LAM also exhibited exceptional adsorption selectivity, boasting a remarkable 9:1 ratio in extracting uranium and vanadium. Furthermore, the strong adhesion of PDA endowed the material with good stability, and the adsorption capacity only decreased by 23 % after 5 cycles. DFT calculations proved that PEI/PA-U was the most stable model. Particularly, the adsorption capacity of LAM in natural seawater can reach 0.99 mg·g−1. With the simple and mild preparation process, along with the excellent adsorption performance, the LAM membrane holds great promise for seawater uranium enrichment.

Highly efficient and selective capture of uranium from groundwater by using an ultrathin 2D MOF nanosheet with pocket-like cavities

Highly efficient and selective removal of uranium from aqueous media is crucial for the sustained development of nuclear energy. Herein, we utilized the intrinsic advantages of two-dimensional (2D) metal–organic frameworks (MOFs) and developed an ultrathin 2D MOF nanosheet with cavity structure. The preconcentration of the pocket-like cavities on the MOF nanosheet and sufficient interactions with the adsorption sites in the cavity structure realized highly efficient removal of uranium from water. Even in the low concentration range of 0.05–1 ppm, relatively high removal ratios and fast adsorption kinetics still can be achieved. Additionally, the MOF nanosheet exhibited extremely high anti-interference capability, which can efficiently reduce uranium pollution (0.05–1 ppm) in acid groundwater to the safe level (≤30 ppb) recommended by World Health Organization, and the removal performance was comparable to that in deionized water. The adsorption mechanism was thoroughly studied by Fourier transform infrared analysis, X-ray photoelectron spectroscopy, and density functional theory calculations, which revealed that the interactions between uranyl ions and the carboxylate groups dominated uranium adsorption, and the H-bonding interactions in the pocket-like cavities played an important role in uranium extraction.

3D/2D MnO/MXene heterostructure with high efficiency for adsorbing uranium

An innovative MnO/Ti3C2 MXene heterostructure, consisting of three-dimensional (3D) MnO nanosheet array directly assembled on two-dimensional (2D) Ti3C2 MXene nanosheets, was synthesized via a simple hydrothermal-annealing strategy for uranium elimination. This unique 3D/2D heterostructure derived substantially high specific surface area (311.9 m2/g) and exposed considerable amount of surface oxygen groups, including surface lattice M–O and adsorbed –OH. Through a comprehensive exploration encompassing adsorbent dosage, pH, ionic strength, initial U(VI) concentration, and environmental conditions, the MnO/Ti3C2 MXene heterostructure demonstrated an extraordinary proficiency and specificity in the removal of U(VI). This composite exhibited an outstanding adsorption capacity of 862.1 mg/g, with a removal efficiency of 99.7 % and rapid kinetics (above 90 % within 20 s). The kinetic study indicated the adsorption process followed chemisorption dynamics and single-layer adsorption behavior. Comprehensive analyses validated the structural integrity and confirmed the successful uranium adsorption via strong interaction between UO22+ and surface unsaturated oxygen groups. Notably, the MnO/Ti3C2 MXene maintained excellent recyclability, highlighting its potential for large-scale applications. It emerges as a promising candidate for uranium removal, offering insights for optimizing composite materials in diverse environmental conditions and fostering advancements in water purification technologies.

Analyzing (3-Aminopropyl)triethoxysilane-Functionalized Porous Silica for Aqueous Uranium Removal: A Study on the Adsorption Behavior.

This study synthesized (3-aminopropyl)triethoxysilane-functionalized porous silica (AP@MPS) to adsorb aqueous uranium (U(VI)). To comprehensively analyze the surface properties of the AP@MPS materials, a combination of SEM, BET, XPS, NMR, and zeta potential tests were conducted. The adsorption experiments for U(VI) revealed the rapid and efficient adsorption capacity of AP@MPS, with the solution condition of a constant solution pH = 6.5, an initial U(VI) concentration of 600 mg × L-1, a maximum U(VI) capacity of AP@MPS reaching 381.44 mg-U per gram of adsorbent, and a removal rate = 63.6%. Among the four types of AP@MPS with different average pore sizes tested, the one with an average pore size of 2.7 nm exhibited the highest U(VI) capacity, particularly at a pH of 6.5. The adsorption data exhibited a strong fit with the Langmuir model, and the calculated adsorption energy aligned closely with the findings from the Potential of Mean Force (PMF) analysis. The outcomes obtained using the Surface Complex Formation Model (SCFM) highlight the dominance of the coulombic force ΔG0coul as the principal component of the adsorption energy (ΔG0ads). This work garnered insights into the adsorption mechanism by meticulously examining the ΔG0ads across a pH ranging from 4 to 8. In essence, this study's findings furnish crucial insights for the future design of analogous adsorbents, thereby advancing the realm of uranium(VI) removal methodologies.

Incorporation of phytic acid into reed straw-derived hydrochar for highly efficient and selective adsorption of uranium(VI)

Abstract An innovative phytic acid modified reed straw-derived hydrochar composite (PA-C-RBC) was prepared by using inexpensive reed straw and non-toxic phytic acid for the removal of uranium(VI) from aqueous environment. Several characterization results showed that PA-C-RBC was rough and porous with a large number of hydroxyl, carboxyl, and phosphate groups. The uranium(VI) adsorption process by PA-C-RBC conformed to pseudo-second-order kinetic and Langmuir models, and the theoretical maximal adsorption capacity could attain 418.78 mg/g at pH 5.0. PA-C-RBC had 72.66 % of selectivity and 6772.99 mL/g of distribution coefficient for U(VI). Due to the strong chelating between the hydroxyl and phosphate groups on PA-C-RBC and U(VI), PA-C-RBC had excellent adsorption selectivity. These finding highlighted a high potential for removing U(VI) from aqueous solutions.

Clay minerals/sodium alginate/polyethylene hydrogel adsorbents control the selective adsorption and reduction of uranium: Experimental optimization and Monte Carlo simulation study

Clay minerals formations are potential geological barrier (host rocks) for the long-rerm storage of uranium tailing in deep geological repositories. However, there are still obstacles to the efficient retardation of uranium because of the competition between negatively charged regions at the clay minerals end face, surface and between layers, as well as low mineralization capacity. Herein, employing a simple method, we used sodium alginate (SA), an inexpensive natural polymer material, polyethylene (PE), and the natural clay minerals montmorillonite (Mt), nontronite (Nt), and beidellite (Bd) to prepare three hydrogel adsorbents, (denoted as Mt/PE-@SA, Nt/PE-@SA, and Bd/PE-@SA), respectively. The application of obtained hydrogel adsorbents further extends to uranium(VI) removal from aqueous. Due to the synergistic action of SA group and PE group, hydrogel adsorbents showed select adsorption and mineralization effect on uranium(VI), among which the maximum uranium(VI) adsorption capacity of Nt/PE-@SA was 133.3 mg·g-1 and Mt/PE-@SA exhibited strong selectivity for uranium(VI) in the presence of coexisting metal ions. Cyclic voltammetry studies indicated the mitigation and immobilization of uranium species onto adsorbents by both reduction and mineralization. Besides, the synergistic adsorption of SA and PE on clay minerals was hypothesized, and the idea was supported by structure optimizations results from Monte Carlo dynamics simulation (MCD). Three obtained hydrogel adsorbents structural model was constructed based on its physicochemical characterization, the low energy adsorption sites and adsorption energies are investigated using MCD simulation. The simulation results show that obtained hydrogel adsorbents have a strong interaction with uranium(VI), which ensures the high adsorption capacity of those materials. Most importantly, this work demonstrates a new strategy for preparing mineral-based hydrogel adsorbents with enough stability and provides a new perspective for uranium(VI) removal in complex environment.

Adsorptive removal of uranium from aqueous solution using graphene oxide reinforced and Mg-doped hydroxyapatite composite

Removal of uranium contamination in wastewater is related to ecological protection and recycling of uranium. In order to explore a better uranium adsorbent, reduced graphene oxide reinforced and magnesium-doped nano-hydroxyapatite composite microspheres (nHA-Mg@rGO) were synthesized in situ by hydrothermal method, which could be used to adsorb uranium in solution efficiently. Magnesium doping significantly increased U(Ⅵ) adsorption, which reached 1614.93 mg/g at pH = 3.5 and T = 298 K. U(Ⅵ) adsorption could be affected by pH, U(Ⅵ) concentration, adsorbent dosage, reaction time, etc. Experimental data was in accord with pseudo-second-order and Sips models. The changes before and after uranium adsorption by nHA-Mg@rGO microspheres could be found from physicochemical characterization results, indicating that hydroxyl and phosphate groups played a vital role. It was concluded that U(Ⅵ) were adsorbed and fixed through the combined effects of complexation, ion exchange and precipitation. The results are helpful for further exploring application of hydroxyapatite composites in uranium removal.