Adsorption Behavior Of Uranium Research Articles

One-step synthesis of phospho-rich, silica-enhanced chitosan aerogel for the efficient adsorption of uranium(VI)

In this study, an amorphous silica reinforced, phosphoric-crosslinked chitosan foam (P-CTS@SixOy) was prepared. The introduction of amorphous silica not only increased the affinity of the adsorbent for uranium, but also improved the stability of the material. The number of active sites of P-CTS@SixOy was increased by the introduction of phosphate groups. The material exhibited excellent uranium adsorption performance with the removal capacity and efficiency of 850.5 mg g−1 and 98.1 %, respectively. After regenerations, the morphology of P-CTS@SixOy still maintained, and the uranium adsorption efficiency remained above 90 %, manifesting the excellent cycle performance of P-CTS@SixOy. In the dynamic adsorption experiment, P-CTS@SixOy successfully concentrated the volume of uranium-containing solution, and exhibited excellent uranium adsorption performance. The analysis of kinetics, isotherms, and thermodynamics manifested that the uranium adsorption behavior of P-CTS@SixOy was a spontaneous, endothermic, monolayer chemical adsorption process. X-ray photoelectron spectroscopy, Scanning Electron Microscope, and Fourier Transform Infrared Spectrometer were used to characterized the P-CTS@SixOy before and after adsorption, which demonstrated that the main interaction mechanism between uranium and P-CTS@SixOy was the complexation. These studies indicated the huge application prospect of P-CTS@SixOy in the treatment of large-scale uranium-containing wastewater.

Effect of fiber surface functionalization on adsorption behavior of uranium from seawater desalination brine

Inspired by the easy availability and modification of fiber-like materials for water treatment and sorption applications, the functionalized natural fiber luffa cylindrica (LC) and synthetic fiber polyacrylonitrile (PAN) have been designed for the uranium adsorption. Seawater desalination brine has a significantly higher concentration of uranyl ion, so it is very meaningful to extract uranyl ions from it. In this paper, the seawater from seawater desalination plant at various treatment stages was collected to evaluate uranium adsorption performance. The effect of flocculant and scale inhibitors on uranium adsorption performance of functional fibers was also studied. The oxime/guanidine co-modified luffa cylindrica fiber (WGLC), guanidine/amidoxime co-modified polyacrylonitrile fiber (PAN-G-AO) and polyethyleneimine modified polyacrylonitrile fiber (PAN-PEI) were synthesized. PAN-G-AO showed excellent uranium capture performance with a high saturation adsorption capacity of 490.20 mg g−1 and rapid adsorption equilibrium at 15 min. Amount of uranium adsorption of three materials declined when flocculant and scale inhibitors were added. The results of adsorption experiments in various stages of seawater desalination solution for 30 days showed that adsorption materials PAN-G-AO had the largest adsorption capacity (18.6 μg g−1) in the concentrated desalinated seawater, which demonstrate promising application potential of the functionalized fiber materials for uranium adsorption from desalinated concentrated seawater.

Construction of dopamine supported Mg(Ca)Al layered double hydroxides with enhanced adsorption properties for uranium

A novel dopamine-supported Mg(Ca)Al layered double hydroxide composite was synthesized by co-precipitation method. The existence of Ca2+ and dopamine could promote the capture of uranium on the layered double hydroxides. In batch experiments, the composite exhibited good uranium removal performance, including high adsorption capacity (687.3 mg/g), strong anti-interference and good reusability (the removal percentage was still higher than 90 % after five cycles). At low initial uranium concentration, the uranium removal percentage on the composite exceeded 99.7 % and the residual concentration of uranium in the solution was <0.03 mg/L, reaching the limited standard of the World Health Organization. The studies of adsorption kinetics and isotherm indicated that the uranium adsorption behavior on the composite conformed to the pseudo-second-order kinetic and Langmuir isotherm models, suggesting that the process was a monolayer adsorption dominated by chemical adsorption. Furthermore, the high-efficiency uranium adsorption on the Mg(Ca)Al layered double hydroxide was mainly attributed to the strong complexation between the active sites (-OH and -NH2) and uranium, the precipitation of interlayer intercalation ions (CO32− and OH−) to uranium and the ion exchange of Ca2+ to uranium. Due to these advantages, the dopamine-supported Mg(Ca)Al layered double hydroxide composite is expected to be used as fine adsorbent to remove uranium from wastewater.

Ultrafast elimination of uranium from aqueous solution by convenient synthesis of phosphonic acid functionalized mesoporous carbon: A combined experimental and density functional theory study

With the speedy advancement of nuclear power, it is strongly desirable to synthesize highly efficacious materials for eliminating uranium from abundant nuclear wastewater under nuclear leakage emergency conditions. Herein, a novel sorbent CMK-3/P (VPA) bearing phosphonic acid was successfully developed by in-situ polymerization of vinylphosphonic acid (VPA) in the presence of mesoporous carbon (CMK-3). Since abundant accessible phosphonic acid ligand had been led into the surface of the CMK-3, the sorbent showed an ultrafast adsorption rate for uranium. The kinetic process demonstrated that uranium adsorption equilibrium on CMK-3/P (VPA) was achieved even within 30 s, suggesting the adsorption rate of the prepared adsorbent far exceeded that of all other sorbents covered formerly. The prepared adsorbent also demonstrated high uranium sorption capacities, and the maximum adsorption capacity (qmax) under 4 M of HNO3 and pH of 4.5 reached 330.1 and 617.2 mg g−1 within 30 s, respectively. Besides, CMK-3/P (VPA) also presented an excellent uranium selectivity, environmental tolerance for uranium immobilization and good structural stability. The preeminent uranium adsorption behavior of CMK-3/P (VPA) was chiefly ascribed to the interplay of the phosphine acid with uranium, and the uranium sorption mechanism of the sorbent at pH of 4.5 was different from that at 4 M of HNO3, which was authenticated by X-ray photoelectron spectrum (XPS) analysis and density function theory (DFT) method. As a result, CMK-3/P (VPA) developed by this work might be seen as a prospective sorbent for eliminating uranium from various kinds of contaminated water under emergency situations.

High efficiency adsorption of uranium in solution with magnesium oxide embedded horse manure-derived biochar

In this study, three kinds of horse manure-derived biochars (HMBM-300, HMBM-500 and HMBM-700) were obtained by calcination of an active horse manure loaded with magnesium chloride in nitrogen at different temperatures (300, 500 and 700 °C). Compared with HMBM-300 and HMBM-700, the Mg2+ in HMBM-500 was completely converted into MgO and no agglomeration of minerals onto HMBM-500 was observed, which led to the existence of abundant active adsorption sites on the surface of HMBM-500. Therefore, HMBM-500 possessed an excellent adsorption performance for uranium species in solution with a short equilibrium time (< 50 min), a fast adsorption rate (5.23 mg/(g·min)), a large adsorption capacity (625.8 mg/g) and a high removal efficiency (98.7%). In other words, the adsorption ability of the magnesium oxide embedded horse manure-derived biochar could be improved by selecting an appropriate calcination temperature. Besides, the adsorption characteristics of the HMBM-500 to uranium could be kept with environmentally interferences, such as coexisting ions and pH, which meant that the horse manure-derived biochar could be appropriate for treating the actual wastewater. Furthermore, the electrostatic interaction, surface complexation and precipitation were proven to play an important role in the adsorption behavior of uranium on HMBM-500 via multiple characterizations and it could be inferred that the high adsorption performance of HMBM-500 was attributed to the coordination and precipitation to uranium with surface active sites. This work showed that the surface modification of biochar was decisive for developing the adsorbents for uranium with high performance.

Adsorption properties and mechanism of uranium by three biomass materials

Abstract Wood fibers, bamboo fibers and rice husk were applied to the adsorption of uranium from aqueous solution to understand the uranium adsorption behavior and mechanism by these natural sorbents. The effects of time, adsorbent particle size, pH, adsorbent dosage, temperature and initial concentration were studied using batch technique. The adsorption mechanism was discussed by isothermal adsorption models, adsorption kinetic models. The results suggested that the three biomass adsorbents showed great efficiency of adsorption for uranium. The adsorption capacity of biosorbents of comparatively small particle size and large dosage is quite high. Uranium adsorption achieved a maximum adsorption amount at around pH 3 for wood fibers and bamboo fibers, and around pH 5 for rice husk. All isotherms fitted well to the Langmuir Freundlich and D-R equation, indicating that the adsorption process is favorable and dominated by ion exchange. Rice husk had a highest adsorption capacity, followed by bamboo fibers, while wood fibers had little uranium adsorption under the studied conditions, and the adsorption capacity was 12.22, 11.27 and 11.04 mg/g, respectively. The equilibrium data was well represented by the pseudo-second-order kinetics, indicating that the adsorption rate was controlled by chemical adsorption. Ion exchange was the main adsorption mechanism, and the exchange ions were mainly Na+ and K+.

A novel freeze-dried natural microalga powder for highly efficient removal of uranium from wastewater

It is of great significance to develop convenient methods and low-cost materials to remove uranium from wastewater. Ankistrodesmus sp., an easy growing green alga, was employed for highly efficient removal of uranium from aqueous solution. The biosorption results under different experimental condition indicate that the alga possess outstanding uranium adsorption ability (qmax = 601.2 mg g−1). Moreover, Ankistrodesmus sp. could be effectively regenerated with hydrochloric acid solution (0.1 M) and used again for uranium adsorption. Even in simulated mine water with various coexisting ions, Ankistrodesmus sp. also exhibits high removal efficiency (95.6%) towards uranium. Furthermore, the adsorption behavior of uranium by alga could be described in the Freundlich isotherms model and the adsorption process was consistent with the pseudo-second-order kinetics model. The characteristic of Fourier transform infrared spectrum, scanning electron microscopy, transmission electron microscope and X-ray photoelectron spectroscopy reveal that –NH2, –COOH, –CONH2 and C–O groups have participated in biosorption process. Therefore, complexation, electrostatic adsorption and ions exchange are the dominated action of uranium biosorption in the algae. All findings in this work suggest that Ankistrodesmus sp. can be a promising candidate for the effective and practical application in field of disposed uranium contamination.

Efficient removal of uranium (VI) by nano-manganese oxide materials: A synthetic experimental and mechanism studies

• Three manganese oxide materials with recyclability was prepared. • The MnO-600 presented wonderful adsorption property for U(VI). • The adsorption capacity of U(VI) on the MnO-600 was 635.4 mg/g. • The removal efficiency remained above 90% after five cycles. Three kinds of nano-manganese oxide materials were prepared at different temperature (500, 600 and 700 °C) using chitosan as the template agent. The results showed that there was no sintering and agglomeration in the calcination of nano-manganese oxide at 600 °C, while the manganese oxide material calcined at 700 °C showed pore collapse and agglomeration and the template agent was incompletely removed in the manganese oxide material calcined at 500 °C. The adsorption properties of uranium (VI) on the three manganese oxide materials were investigated. The experimental results showed that the adsorption behavior conformed to the pseudo-second-order kinetics and Langmuir isotherm models, revealing that the adsorption behavior of uranium (VI) on manganese oxide materials was a uniform and monolayer chemical adsorption process. The adsorption capacity of MnO-600 was 635.4 mg/g and the adsorption efficiency was above 90% after five cycles. In conclusion, the novel manganese oxide materials would have a prospect for application in wastewater treatment.

Preparation of ring crosslinked poly (p-nitrile) nanoparticles and Study on adsorption behavior of uranium (VI)

Cyclo crosslinked polyphosphazenes (PPNs) were prepared by Hexachlorocyclotriphosphazene (HCCP) with unique P = n structure and active p-cl group and green compound phloretin. The synthesis pro cess of polyphosphazene nanospheres with Hexachlorocyclotriphosphazene as the main body and phloretin was discussed. The effects of pH value and solid-liquid ratio of solution on the adsorption of uranium by pol yphosphazene nanospheres were studied. The results show that polyphosphazene nanospheres are off white powder in appearance and spherical in microstructure. When the pH value of the solution is 4 and the solid-l iquid ratio is 0.5g ·L-1, the maximum adsorption rate of uranium is obtained.

Rapid removal of uranium(Ⅵ) using functionalized luffa rattan biochar from aqueous solution

Due to its reliable performance and low manufacturing cost, biochar has gradually attracted attention in the treatment of uranium-containing wastewater. Herein, Luffa rattan (LR), a biowaste material, was used to synthesize functional biochar (F-LRBC) to adsorb U(VI) from aqueous solutions for the first time. The effect of solution pH, contact time and initial concentration of uranyl ions on uranium(Ⅵ) adsorption by F-LRBC was evaluated. FT-IR and SEM analysis confirmed that there are abundant oxygen-containing functional groups and pores on the surface of F-LRBC. Experiments demonstrated that the adsorption behavior of uranium(Ⅵ) by F-LRBC is spontaneous and efficient. The maximum adsorption capacity of F-LRBC for uranyl ions predicted by the Langmuir model was higher than that of most biochar adsorbent. The adsorption mechanism of uranyl ions on F-LRBC is complicated, including electrostatic interaction, complexation and physical adsorption.

High capacity amidic succinic acid functionalized mesoporous silica for the adsorption of uranium

The nuclear reactors operating worldwide are currently using the uranium mined from the resources available on the earth's crust. A significant volume of aqueous waste containing a small quantity of uranium was generated during the processing of ores. There is a growing demand to remove this toxic uranium from these aqueous streams, owing to the limit of tolerable daily intake (15 μg L−1) for uranium imposed by the World Health Organization. This demand throws huge challenges to the separation chemists to engineer the solid phase adsorbents having high capacity, excellent selectivity and satisfactory throughputs for processing a vast quantity of aqueous waste containing traces of uranium. In this context, the task specific amidic succinic acid (SUC) functional groups tailored on mesoporous silica having wide porosity and large surface area have been prepared and characterized by BET surface area, pore and particle size distribution, thermogravimetry, SEM-EDX analysis, FT-IR and Raman spectroscopy. The adsorption behavior of uranium (VI) from the aqueous phase on the tailored adsorbent (MCM-SUC) was studied as a function of pH of the aqueous phase, duration of equilibration, uranium concentration in the aqueous phase, and the results were compared with the adsorbent containing the same functional group but grafted on silica gel (Si-SUC), which exhibited adsorption capacity of 61 mg g−1. The fast kinetics of adsorption and significantly high Langmuir adsorption capacity of uranium (807 mgg −1), as compared to the other mesoporous adsorbents reported in literature, achieved in MCM-SUC was due to controlled synthesis of SUC functionalized mesoporous silica that favoured high degree of SUC number density on the mesoporous material. The adsorbed uranium was recovered using 0.1 M nitric acid.

Diethylenetriamine tethered mesoporous silica for the sequestration of uranium from aqueous solution and seawater

Mesoporous silica (MCM-41) with large surface area and porosity has been synthesized and tethered covalently with the uranium (VI) specific ligand, namely diethylenetriamine (DETA) on MCM-41. The adsorbent, abbreviated as MCM-DETA, was characterized by BET surface area, BJH pore size and particle size distribution, thermogravimetry, SEM-EDX analysis, and FT-IR spectroscopy, and studied for the adsorption of uranium from aqueous solution. The parameters evaluated were the effect of pH of the aqueous phase, duration of equilibration, concentration of uranium in the aqueous phase, and the effect of interfering ions on the adsorption of uranium (VI) on MCM-DETA. The adsorption behavior of uranium from seawater (U(VI) = 10 mg.L−1) was studied by batch equilibration method. The results revealed that MCM-DETA showed rapid adsorption kinetics (k2 = 2.85 × 10-3 mol.L−1. min−1), extremely large Langmuir adsorption capacity (1067 mg.g−1), good selectivity over other interfering ions, and efficient adsorption of uranium from seawater (680 mg.g−1) spiked with uranium, indicating that MCM-DETA a promising candidate for the adsorption of uranium from aqueous solution and seawater.

Fabrication of amidoximated polyacrylonitrile nanofibrous membrane by simultaneously biaxial stretching for uranium extraction from seawater

A novel amidoximated polyacrylonitrile nanofibrous membrane (AO-PAN NFM) is synthesized by post-amidoximation of PAN NFM prepared via simultaneously biaxial stretching for the first time. With layered stack structure consisting of cross-linked nanofibers, the AO-PAN NFM is characterized by high specific surface area and outstanding hydrophilicity. Accordingly, it exhibits high uranium adsorption capacity, excellent selectivity, outstanding reusability with fast and efficient desorption response. Meanwhile, the chemical adsorption dominates the uranium adsorption behavior of AO-PAN NFM. Notably, compared with electrospinning and blow spinning processes, the simultaneously biaxial stretching method has unique advantages, such as membrane thickness control, good mechanical properties and high productivity of large-scalable production etc. The novel AO-PAN NFM produced by the new stretching method shows great application potential as a new strategy for uranium extraction from seawater to support future nuclear energy generation.

Effects of speciation on uranium removal efficiencies with polyamine-functionalized silica composite adsorbent in groundwater

Uranium (Ⅵ) exists as many species in natural water systems. In the recent years, its contamination to groundwater has been reported more frequently. To investigate the effects of speciation on the removal of uranium, this work investigated the uranium adsorption behaviors of a polyamine-grafted silica composite named SAER at the concentration level of μg/L in the alkaline carbonate solutions with other four resins. Results suggested that the change of uranium speciation had minor effect on the adsorption efficiencies of SAER, except the addition of calcium. This was resulted from that the protonated tetraethylenepentamine had a much higher affinity to the electronegative uranyl-carbonate species, leading to the complete removal of uranium through the simultaneous anion exchange and chemical transformation mechanisms; Column experiments confirmed that merely a small portion of calcium while no magnesium cations were involved in the uranium adsorption in the simulated groundwater. Finally, the integrated removal mechanisms were proposed. Overall, this work demonstrated the feasibility of a novel adsorbent for the effective removal of uranium from different water matrices as well as the mechanisms underlying the interaction of uranium and the functional groups on the adsorbents. Furthermore, it enhanced the understanding of uranium removal under environmentally relevant conditions.

Modification of Nylon 6,6 with Trioctylphosphine Oxide for Uranium Removal from Aqueous Solution

The study deals with the uranium removal from a raffinate solution (nitric acid waste solution from the production of uranium yellowcake) using an extractant-impregnated material. A polyamide sheet (Nylon 6,6) was impregnated with trioctylphosphine oxide and tested for uranium removal. The factors affecting the impregnation process, namely, extractant concentration, impregnation time, volume/mass ratio, impregnation temperature, and diluent type were studied. The effect of the initial uranium concentration, adsorption temperature, contact time, and pH on the uranium adsorption on the prepared sheet was also studied. The uranium adsorption behavior was described using adsorption isotherms.

Highly efficient uranium(VI) removal from aqueous solution using poly(cyclotriphosphazene-co-4,4′-diaminodiphenyl-ether) crosslinked microspheres

Poly(cyclotriphosphazene-co-4,4′-diaminodiphenyl ether) crosslinked microspheres with active amino groups on the surface were prepared by one-step precipitation polymerization method. The as-prepared material were characterized by means of FTIR, XPS, XRD, EDS and SEM. The effects of pH, time of contact, dosage, initial concentration and temperature on the adsorption of uranium(VI) by the crosslinked microspheres were studied, and the adsorption mechanism was elucidated. Under the optimized adsorption conditions, the adsorption removal efficiency reached 97.03%. The experimental results fit the Langmuir isotherm model and adsorption processes comply with the pseudo-second-order kinetic model. Thermodynamic data revealed that the adsorption behavior of uranium(VI) on the microspheres was spontaneous and exothermic.

Carbothermal reduction for preparing nZVI/BC to extract uranium: Insight into the iron species dependent uranium adsorption behavior

Abstract Currently, a lot of uranium containing wastewater was generated in China, which required efficient treatment before being discharged. Immobilization of uranium on ZVI has attracted many concerns from researchers in the world wide. Surface oxidation and agglomeration limited the efficiency of nano zero-valent iron (nZVI) in remediation of uranium pollution. In this work, a green carbothermal reduction process was conducted to prepare environmental friendly biochar-supported ZVI (nZVI/BC). Immobilization behavior of uranium on nZVI/Cs, oxidized nZVI/Cs and Fe3O4 from wastewater were investigated. The iron salt was converted into iron oxides at 700 °C, further being reduced into nZVI in the presence of ferric chloride and ferric nitrate being carbonization of starch at 800 and 900 °C. The uranium adsorption capacities were different from the carbonization temperature and iron sources, which depended on the transformation of iron species. The maximum adsorption capacities of nano-flake FeCl/C (1:4–900) and nanoparticles FeN/C (1:4–900) for U(VI) were 34.82 and 55.14 mg/g. The removal efficiencies of FeCl/C (1:4–900) and nanoparticles FeN/C (1:4–900) were higher than that of 44% for C–Fe3O4. The SEM-mapping and XPS analysis of nZVI/Cs after U(VI) adsorption indicated that the immobilization of U(VI) was ascribed to simultaneous adsorption and reduction.

Efficiency and mechanism of adsorption of low concentration uranium in water by extracellular polymeric substances

Extracellular polymeric substances (EPS) of uranium adsorbent was first extracted from the aerobic activated sludge of municipal wastewater treatment plant as raw material. The structure and surface morphology of EPS was characterized by FTIR, SEM-EDX, 3D-EEM, and XPS. The 3D-EEM spectra of EPS revealed that there are Tryptophan-like protein and Humus which can adsorb uranium in the EPS. The results of XPS indicated that the EPS surface contained active functional groups (COOH,CONH2,-H2PO4,OH,NH2 and so on) which all react with uranium, and the C, N, O elements play an important role in the reaction. The static batch test was used to study the adsorption behavior of uranium on the EPS, and the effects of pH, dosage of EPS and initial concentration of the solution on the removal of uranium by EPS were investigated. The adsorption isotherm, thermodynamics and kinetic models were used to match the mechanism of the interaction between EPS and uranium. Batch adsorption experiments revealed that the pH value had a great influence on the adsorption effect of EPS, and the optimal solution pH for uranium adsorption was around 6.0 with the removal efficiency of uranium was about 93% in the condition of neutral. Freundlich (R2 ≈ 0.997) and Langmuir (R2 ≈ 0.9931) models can get a good fitting effect, indicating that the adsorption of uranium by EPS had both monolayer adsorption and multilayer adsorption. EPS and uranium were combined disorderly and ion exchange mechanism could be involved. In this study, the active groups on the surface of EPS were also involved in the chemisorption process of uranium adsorption. The maximum adsorption capacity of EPS by Langmuir fitting was 333.3 mg/g. We conclude EPS is a potential adsorbent for radionuclide treatment.

URANIUM REMOVAL FROM AQUEOUS SOLUTION USING TRI-N-BUTYL PHOSPHATE AND DI-2-ETHYLHEXYL PHOSPHORIC ACID FUNCTIONALIZED POLYESTER SHEET AND CHARCOAL AS ADSORBENTS

The present investigation deals with the removal of uranium from a nitric acid waste solution (Raffinate solution: produce during yellow cake of uranium production) using the extraction chromatography technique (solvent impregnated material) ), where Tri-N-butyl phosphate (TBP) and Di-2-ethylhexyl phosphoric acid (D2EHPA) solvents were impregnated upon polyester sheet and charcoal respectively then the impregnated resin were tested for uranium removal. Thus, the factors affecting the impregnation process namely, solvent concentration, impregnation time, volume/mass ratio, impregnation temperature and diluents type were studied. Secondly the influences of initial uranium concentration, adsorption temperature, contact time, pH on the uranium adsorption on the prepared materials were studied. From the results the isotherm models also calculated to determine uranium adsorption behavior by the prepared TBP and D2EHPA impregnated polyester sheet and charcoal respectively. Both prepared materials were found to be fitted with Langmuir than Freundlich model isotherm.

Adsorption of U(VI) from eutrophic aquesous solutions in a U(VI)-P-CO3 system with hydrous titanium dioxide supported by polyacrylonitrile fiber

Hydrous titanium dioxide supported by commercially available polyacrylonitrile fiber (c-PANF/TiO2·xH2O) was synthesized via a simple blending method to first investigate its U(VI) adsorption behavior from eutrophic aqueous solution in a U(VI)-P-CO3 system. TG-DSC and XRD analysis demonstrated that the material had good structural stability during the adsorption process. The theoretical maximum U(VI) adsorption capacity (qe) of c-PANF/TiO2·xH2O calculated from the Langmuir isotherm was ~256 mg/g. However, high initial solution pH values, total dissolved carbonate concentration and ionic strength could inhibit U(VI) chemisorption. In particular, qe and sorption efficiency (S%) values were maintained at ~100 mg/g and > 80% for the [P] range of 0 to 150 μmol/L, and then they rapidly decreased once [P] exceeded 150 μmol/L due to the competitive adsorption between HPO42-/H2PO4- and uranium anionic complexes such as UO2(CO3)34−, UO2(CO3)22− and UO2PO4-. XPS analysis suggested that Ti3+ defects and OH groups on the composite surface could be the U(VI) adsorption sites. Moreover, a 0.1 mol/L H2SO4 solution was found to be the most effective desorption agent. The findings reported in this study are significant in regards to the extraction of uranium from eutrophic seawater and for the understanding of uranium adsorption behaviors in multi-carbonate systems.