Kinetics and Thermodynamics Studies on the Recovery of Thorium Ions Using Amino Resins with Magnetic Properties

Constructing amidoxime adsorption sites on the core-shell structured natural silk protein for uranium capture

Amidoxime-based fiber adsorbents hold significant promise for uranium extraction. However, a notable issue is that these adsorbents primarily originate from synthetic polymer materials, which, aside from providing good mechanical support, have no other functions. In recent study, we shifted our focus to silk fiber (SF), a natural protein fiber known for its unique core-shell structure and rich amino acids. The shell layer, due to its abundant functional groups, makes it easily modifiable, while the core layer provides excellent mechanical strength. Leveraging these inherent properties, an amidoxime-based fiber adsorbent was developed. This adsorbent utilizes amino and carboxyl groups for enhanced performance synergistically. This method involves establishing uranium affinity sites on the outer sericin layer of SF via chemical initiation of graft polymerization (CIGP) and amidoximation (SF-g-PAO). The water absorption ratio of SF-g-PAO is as high as 601.16 % (DG = 97.17 %). Besides, SF-g-PAO demonstrates an exceptional adsorption capacity of 15.69 mg/g in simulated seawater, achieving a remarkable removal rate of uranyl ions at 95.06 %. It can withstand a minimum of five adsorption-elution cycles. Over a 4-week period in natural seawater, SF-g-PAO displayed an adsorption capacity of 4.95 mg/g. Furthermore, SF-g-PAO also exhibits impressive uranium removal efficiency in real nuclear wastewater, with a removal rate of 63 % in just 15 min and a final removal rate of 90 %. It is hoped that this SF-g-PAO, prepared through this straightforward method and characterized by the synergistic action of amino and carboxyl groups, can offer innovative insights into the development of uranium extraction adsorbents.

γ-Resistant Microporous CAU-1 MOF for Selective Remediation of Thorium

A simple solvothermal method was used to synthesize a metal-organic framework (MOF) with an Al metal entity, viz., CAU-1 NH₂. The synthesized MOF was characterized using different techniques like X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy (SEM), field emission SEM (FE-SEM), transmission electron microscopy, small-angle X-ray scattering, positron annihilation lifetime spectroscopy, and X-ray photoelectron spectroscopy. The radiation stability was evaluated by irradiating the material up to a cumulative dose of 2 MGy using ⁶⁰Co for the first time. The studies showed a remarkable gamma irradiation stability of the material up to 1 MGy. The porosity and surface area of the synthesized MOF were determined by Brunauer-Emmett-Teller, which showed a high specific surface area of 550 m²/g. The pH dependence study of Th uptake from an aqueous solution was performed from pH 2-8, followed by adsorption isotherm and adsorption kinetics studies. These results revealed that the Langmuir and pseudo-second-order kinetic models can be well adapted for understanding the Th uptake and kinetics, respectively. The synthesized MOF exhibited an ∼404 mg/g thorium adsorption capacity. Selectivity studies of adsorption of Th w.r.t. to U and different metal ions such as Cu, Co, Ni, and Fe showed that Th gets adsorbed preferentially as compared to other metal ions. In addition, the MOF could be used multiple times without much deterioration.

MOF-implanted poly (acrylamide-co-acrylic acid)/chitosan organic hydrogel for uranium extraction from seawater

In this study, a composite hydrogel with a low swelling ratio, excellent mechanical properties, and good U (VI) adsorption capacity was developed by incorporating a metal-organic framework (MOF) with a poly (acrylamide-co-acrylic acid)/chitosan (P(AM-co-AA)/CS) composite. The CS chain, which contains NH₂, reduces the swelling ratio of the hydrogel to 4.17 after 5 h of immersion in water. The coordinate bond between the MOF and carboxyl group on the surface of P(AM-co-AA)/CS improves the mechanical properties and stability of P(AM-co-AA)/CS. The U(VI) adsorption capacity of P(AM-co-AA)/CS/MOF-808 is 159.56 mg g^-1 at C₀ = 99.47 mg L^-1 and pH = 8.0. The adsorption process is well fitted by the Langmuir isotherm and pseudo-second-order model. The P(AM-co-AA)/CS/MOF-808 also exhibits good repeatability and stability after five adsorption-desorption cycles. The uranium adsorption capacity of the developed adsorbent after one month in natural seawater is 6.2 mg g^-1, and the rate of uranium adsorption on the hydrogel is 0.21 mg g^-1 day^-1.

The Study of Amidoxime-Functionalized Cellulose Separate Th(IV) from Aqueous Solution

Selective extraction of low-concentration thorium (Th(IV)) from wastewater is a very important research topic. In this paper, amidoxime cellulose was synthesized, and its composition and structure were characterized by FT-IR, SEM, XPS, and elemental analysis. The adsorption experiment results showed that the adsorption reaction was a spontaneous exothermic process. When the solid–liquid ratio was 0.12 g/L and the pH value was 3.5, the adsorption percentage of the Th(IV) in water onto amidoxime-functionalized cellulose (AO-CELL) could reach over 80%. The maximum adsorption capacity can reach to 450 mg/g. At the same time, the adsorption selectivity, desorption process and reusability of the material were also studied. The results showed that the AO-CELL had a good selectivity for Th(IV) in the system with Sr²⁺, Cu²⁺, Mg²⁺, Zn²⁺, Pb²⁺, Ni²⁺, and Co²⁺ as co-ions. In the nitric acid concentration of 0.06 mol/L system, the AO-CELL desorption rate of Th(IV) can reach 95%, and the adsorption rate of Th(IV) in aqueous solution of AO-CELL is still above 60% when the AO-CELL is reused four times. The above results show that the amidoxime cellulose adsorption material synthesized by our research group has good selective adsorption performance for Th(IV) of a low concentration in an aqueous solution and has a good practical application value.

Methacrylate-Based Polymeric Sorbents for Recovery of Metals from Aqueous Solutions

The industrialization and urbanization expansion have increased the demand for precious and rare earth elements (REEs). In addition, environmental concerns regarding the toxic effects of heavy metals on living organisms imposed an urgent need for efficient methods for their removal from wastewaters and aqueous solutions. The most efficient technique for metal ions removal from wastewaters is adsorption due to its reversibility and high efficiency. Numerous adsorbents were mentioned as possible metal ions adsorbents in the literature. Chelating polymer ligands (CPLs) with adaptable surface chemistry, high affinity towards targeted metal ions, high capacity, fast kinetics, chemically stable, and reusable are especially attractive. This review is focused on methacrylate-based magnetic and non-magnetic porous sorbents. Special attention was devoted to amino-modified glycidyl methacrylate (GMA) copolymers. Main adsorption parameters, kinetic models, adsorption isotherms, thermodynamics of the adsorption process, as well as regeneration of the polymeric sorbents were discussed.

Separation of thorium(IV) from aquatic media using magnetic ferrite nanoparticles

The separation and recovery of thorium from monazite is critical to the sustainable development of the nuclear industry as well as to environmental safety. Also, the removal of radionuclides from polluted sources is a critical issue in environmental control. Magnetic ferrite nanoparticles (MCMF-NP, Co0.5Mn0.5Fe2O4) were synthesized (4–22 nm in size) and characterized. MCMF-NP was investigated for Th(IV) separation from their aqueous medium under various test conditions of acidity, time, and Th(IV) concentration, in line with the uptake capacity. The amount of thorium adsorbed is improved when pH, time, and initial concentration are increased. The maximum uptake of Th(IV) by MCMF-NP was observed at pH 3.5–4 and a contact time of 180 min. A favorable adsorption mechanism was shown in the pseudo-second-order rate. Isotherm analysis shows an adequate process described by the Langmuir isotherm. MCMF-NP is an adsorbent capable of successful disposal of Th(IV) from waste solutions with a high uptake of 81.3 mg of Th(IV)/g of MCMF-NP. The possibility of re-using the MCMF-NP, adding value to this content as a way of compensating for the disposal costs, was studied and disused. MCMF-NP shows a good separation of thorium(IV) from monazite leach liquor as well as from wastewater samples.

Preparation of TiO2/cellulose nanocomposites as antibacterial bio-adsorbents for effective phosphate removal from aqueous medium

The design of environmentally benign bio-adsorbents for the removal of phosphate from aqueous medium was an economic and effective way for controlling eutrophication. Herein, we prepared three kinds of TiO₂/cellulose (CE-Ti) nanocomposites by a facile hydrolysis-precipitation method, and used them as antibacterial bio-adsorbents for the removal of phosphate from aqueous medium. Multiple techniques including Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and thermogravimetric analysis (TGA) were employed to characterize the nanostructure and characteristics of the prepared CE-Ti nanocomposite. The adsorption capacity of the CE-Ti was 19.57 mg P g^-1 according to the Langmuir model, which was 6 times higher than that of CE. Importantly, the bacterial inhibition zone of the CE-Ti was 2.88 mm (that of CE was 0 mm), indicating that CE-Ti had good antibacterial activity that could reduce the attachment of the microorganism to the surface of CE-Ti, which was suitable for long-term phosphate removal. Moreover, the CE-Ti had good adsorption selectivity and anti-interference capability, according to interfering ions and ion strength experiments. Furthermore, Ti⁴⁺ leakage tests suggested that CE-Ti was highly stable under acidic, neutral and alkali conditions. These results indicated that the CE-Ti nanocomposite could be utilized as a promising antibacterial bio-adsorbent for effective phosphate removal from aqueous medium.

Synthesis of selective biodegradable amidoxime chitosan for absorption of Th(IV) and U(VI) ions in solution

Radionuclide extraction from wastewater is a long-term process, in which the study on the reuse and decomposition of adsorbents provides the ability to complete the post-treatment after adsorption. Herein, A novel biodegradable amidoxime chitosan has been synthesized through one-step without crosslinking agent and characterized by FT-IR, SEM, XPS, TGA and element analysis. The batch adsorption experiments of U(VI) and Th(IV) on AO-CTS adsorbent were studied and maximum adsorption of U(VI) and Th(IV) were 97 and 56 mg/g, respectively. The U(VI) and Th(Ⅳ) can be effectively desorbed from the AO-CTS materials at low acidity, The AO-CTS can be reused 6 times without reducing absorbency for U(VI) and Th(Ⅳ). When finish the adsorption process, the AO-CTS can be degraded by lysozyme at room temperature, there were no toxic or harmful substances are produced.

Synthesis and Adsorption Behavior of Microporous Iron-Doped Sodium Zirconosilicate with the Structure of Elpidite

Decontamination of water from radionuclides contaminants is a key priority in environmental cleanup and requires intensive effort to be cleared. In this paper, a microporous iron-doped zeolite-like sodium zirconosilicate (F@SZS) was designed through hydrothermal synthesis with various Si/Zr ratios of 5, 10, and 20, respectively. The synthesized materials of F@SZS materials were well characterized by various techniques such as XRD, SEM, TEM, and N2 adsorption–desorption measurements. Furthermore, the F@SZS-5 and F@SZS-10 samples had a crystalline structure related to the Zr–O–Si bond, unlike the F@SZS-20 which had an overall amorphous structure. The fabricated F@SZS-5 nanocomposite showed a superb capability to remove cesium ions from ultra-dilute concentrations, and the maximum adsorption capacity was 21.5 mg g–1 at natural pH values through an ion exchange mechanism. The results of cesium ions adsorption were found to follow the pseudo-first-order kinetics and the Langmuir isotherm model. The microporous iron-doped sodium zirconosilicate is described as an adsorbent candidate for the removal of ultra-traces concentrations of Cs(I) ions.

The influence of cobalt manganese ferrite nanoparticles (Co0.5Mn0.5Fe2O4) on reduction of hazardous effects of vanadate in adult rats

Effect of cobalt manganese ferrite nanoparticles (M-NPs) (Co0.5Mn0.5Fe2O4) on vanadium hazards was assessment in the present study. Four groups of adult male albino rats [control group and three variably treated groups with ammonium metavanadate accompanied with or without cobalt M-NPs] were studied. The oral administration of ammonium metavanadate (Am.V) (20 mg/kg b.wt.) demonstrated the facility of vanadium to distribute and accumulate in the distinctive body organs and ordered as kidney > liver > lung > brain > spleen. Also, Am.V administration induce a significant disturbance in many physiological parameters (RBS, cholesterol, triglyceride, aspartate transaminase, alanine transaminase, Alb., bilirubin, Alk.Ph., urea, creat., Hb%, red blood cell count and packed cell volume) which might be expected to the liberation of free radicals according to the vanadium intoxication or its ability to disturb many body metabolisms. On the other hand, the intraperitoneal administration of 5% M-NPs in parallel with Am.V orally administration showed the ability of M-NPs to reduce Am.V dangerous impacts, which might be resulted from the essentiality of M-NPs metals to the body metabolism and to its free radicals scavenging properties. So, M-NPs could reduce Am.V hazardous effects.

Fabrication of Mesoporous NaZrP Cation-Exchanger for U(VI) Ions Separation from Uranyl Leach Liquors

As the demand for uranium production-based energy worldwide has been increasing in the last decades to maintain nuclear growth for electricity production, there are great efforts towards developing an easy and inexpensive method for uranium extraction and separation from its ores. For this purpose, mesoporous inorganic cation exchangers provide an efficient separation technology that can help streamline production and lower overall cost. This study describes the development of nano-structured mesoporous sodium zirconium phosphate (NaZrP-CEX) for separation and extraction of uranyl ions from real samples. The fabricated NaZrP-CEX was well characterized by various techniques such as X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM), N2 adsorption/desorption, Dynamic light scattering (DLS) and zeta potential). The kinetics/thermodynamic behaviors of uranyl ion adsorption into NaZrP-CEX from an aqueous solution were minutely studied. The kinetic studies showed that the pseudo-second order model gave a better description for the uptake process. The negative value of ΔG indicate high feasibility and spontaneity of adsorption. Finally, mesoporous NaZrP-CEX can be regenerated using both of HNO3 (0.05 M) or HCl (1 M) up to seven cycles of operation.

Nano-sized architectural design of multi-activity graphene oxide (GO) by chemical post-decoration for efficient uranium(VI) extraction

The introduction of organic groups onto graphene oxide (GO) platelets can supply additional active sites for adsorption of uranium(VI) (U(VI)) to improve the adsorption capacity. However, as a result of the existence of stabilizing π-conjugation system, a facile and effective modification method remains a challenge. Therefore, a novel strategy is exploited by nano-sized architectural design of multi-activity GO through post-decoration with amidoxime functionalized diaminomaleonitrile (DM-AO). The post-modification of DM-AO successfully activated the inert sites in GO platelets. Meanwhile, the amidoxime group in DM-AO can improve the adsorption selectivity. Adsorption amount of U(VI) on the as prepared GO-DM-AO reached at 935 mg g^-1, which is increased by 209% increment compared with that of pristine GO at the same concentration. The adsorption efficiency of GO-DM-AO is greatly improved, and the time to reach the adsorption equilibrium is half of that of GO. Excitingly, the excellent removal efficiency could still maintained even after 5 cycles of adsorption-desorption. The outstanding adsorption amount, short adsorption equilibrium time, and excellent removal efficiency can provide a theoretical guidance for further immobilization of U(VI) from seawater.

Functionalized Sugarcane Bagasse for U(VI) Adsorption from Acid and Alkaline Conditions

The highly efficient removal of uranium from mine tailings effluent, radioactive wastewater and enrichment from seawater is of great significance for the development of nuclear industry. In this work, we prepared an efficient U(VI) adsorbent by EDTA modified sugarcane bagasse (MESB) with a simple process. The prepared adsorbent preserves high adsorptive capacity for UO₂²⁺ (pH 3.0) and uranyl complexes, such as UO₂(OH)⁺, (UO₂)₂(OH)₂²⁺ and (UO₂)₃(OH)₅⁺ (pH 4.0 and pH 5.0) and good repeatability in acidic environment. The maximum adsorption capacity for U(VI) at pH 3.0, 4.0 and 5.0 is 578.0, 925.9 and 1394.1 mg/g and the adsorption capacity loss is only 7% after five cycles. With the pH from 3.0 to 5.0, the inhibitive effects of Na⁺ and K⁺ decreased but increased of Mg²⁺ and Ca²⁺. MESB also exhibits good adsorption for [UO₂(CO₃)₃]^4- at pH 8.3 from 10 mg/L to 3.3 μg/L. Moreover, MESB could effectively extract U(VI) from simulated seawater in the presence of other metals ions. This work provided a general and efficient uranyl enriched material for nuclear industry.

Decontamination of radioactive cesium ions using ordered mesoporous monetite

We report herein the fabrication of an environmentally friendly, low-cost and efficient nanostructured mesoporous monetite plate-like mineral (CaHPO₄) as an adsorbent for removal of radioactive cesium ions from aqueous solutions. The phase and textural features of the synthesized mesoporous monetite were well characterized by XRD, FTIR, SEM, HRTEM, DLS, TGA/TDA, and N₂ adsorption/desorption techniques. The results indicate that the cesium ions were effectively adsorbed by the mesoporous monetite ion-exchanger (MMT-IEX) above pH 9.0. Different kinetic and isotherm models were applied to characterize the cesium adsorption process. The fabricated monetite exhibited a monolayer adsorption capacity up to 60.33 mg g⁻¹ at pH of 9.5. The collected data revealed the higher ability of CaHPO₄ for the removal of Cs(i) from aqueous media in an efficient way.

This study involves the identification of environmentally friendly, low-cost and efficient nanostructured mesoporous monetite plate like mineral as an adsorbent for removal of cesium from aqueous solutions.

Novel Metal-Organic Framework (MOF) Based Composite Material for the Sequestration of U(VI) and Th(IV) Metal Ions from Aqueous Environment

The combination of magnetic nanoparticles and metal-organic frameworks (MOFs) has demonstrated their prospective for pollutant sequestration. In this work, a magnetic metal-organic framework nanocomposite (Fe₃O₄@AMCA-MIL53(Al) was prepared and used for the removal of U(VI) and Th(IV) metal ions from aqueous environment. Fe₃O₄@AMCA-MIL53(Al) nanocomposite was characterized by TGA, FTIR, SEM-EDX, XRD, HRTEM, BET, VSM (vibrating sample magnetometry), and XPS analyses. A batch technique was applied for the removal of the aforesaid metal ions using Fe₃O₄@AMCA-MIL53(Al) at different operating parameters. The isotherm and kinetic data were accurately described by the Langmuir and pseudo-second-order models. The adsorption capacity was calculated to be 227.3 and 285.7 mg/g for U(VI) and Th(IV), respectively, by fitting the equilibrium data to the Langmuir model. The kinetic studies demonstrated that the equilibrium time was 90 min for each metal ion. Various thermodynamic parameters were evaluated which indicated the endothermic and spontaneous nature of adsorption. The collected outcomes showed that Fe₃O₄@AMCA-MIL53(Al) was a good material for the exclusion of these metal ions from aqueous medium. The adsorbed metals were easily recovered by desorption in 0.01 M HCl. The excellent adsorption capacity and the response to the magnetic field made this novel material an auspicious candidate for environmental remediation technologies.

A Schiff base/quaternary ammonium salt bifunctional graphene oxide as an efficient adsorbent for removal of Th(IV)/U(VI)

A novel approach for facile covalent functionalization of graphene oxide (GO) was proposed in the present study in order to effectively avoid necessary anhydrous conditions and the usage of harsh reagents during the chemical functionalization of GO. Herein, a GO derivative that was functionalized with a primary amine derivative bearing a positively charged quaternary ammonium group, GO-S, was synthesized through a Schiff base condensation reaction between the amine groups of the primary amine derivative and the aldehyde groups of GO. The introduction of the quaternary ammonium groups can prevent GO from stacking and improve the dispersibility of GO after modification. The formation of imine bonds (NCH) between the primary amine and GO has been confirmed by Fourier transform infrared and X-ray photoelectron spectroscopy. The GO-S demonstrated good dispersion stability in aqueous medium and also exhibited better adsorption performance than GO for Th(IV) and U(VI), with a maximum thorium adsorption capacity of 2.22mmol/g and a maximum uranium adsorption capacity of 0.83mmol/g, suggesting a great potential for the application of graphene oxide-based materials for facilitating the removal of Th(IV) and U(VI) from nuclear waste solutions.