Carboxymethyl cellulose and metal-organic frameworks immobilized into polyacrylamide hydrogel for ultrahigh efficient and selective adsorption U(VI) from seawater.

Metal-organic frameworks (MOF)-polymer hybrid hydrogel solves the processable forming of MOF powder and energy consumption of uranium extraction. However, the hybrid hydrogel by conventional synthesis methods inevitably lead to MOF agglomeration, poor filler-polymer interfacial compatibility and slowly adsorption. Herein, we designed that ZIF-67 was implanted into the carboxymethyl cellulose/polyacrylamide (CMC/PAM) by network-repairing strategy. The carboxyl and amino groups on the surface of CMC/PAM drive the uniform growth of ZIF-67 inside the CMC/PAM, which form an array of oriented and penetrating microchannels through coordination bonds. Our strategy eliminate the ZIF-67 agglomeration, increase the interfacial compatibility between MOF and polymer. The method also improve the free and fast diffusion of uranium in CMC/PAM/ZIF-67 hydrogel. According to the experimental, these enhancements synergistically enabled the CMC/PAM/ZIF-67 have a maximum adsorption capacity of 952 mg g-1. The adsorption process of CMC/PAM/ZIF-67 fits well with pseudo-second-order model and Langmuir isotherm. Meanwhile, the CMC/PAM/ZIF-67 maintain a high removal rate (87.3 %) and chemical stability even during ten adsorption-desorption cycles. It is worth noting that the adsorption amount of CMC/PAM/ZIF-67 in real seawater is 9.95 mg g-1 after 20 days, which is an ideal candidate adsorbent for uranium extraction from seawater.

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

In this work, the modified­sodium 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 modified­sodium 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 modified­sodium 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.

Investigating the rus and petI operon expression patterns in exposed Acidithiobacillus ferrooxidans sp. FJ2 to different doses of gamma irradiation.

The bioleaching process is developing as an economic and successful biotechnology method in the metallurgy industry. Acidithiobacillus ferrooxidans is one of the most important bacteria involved in uranium bioleaching which converts insoluble U4+ to soluble U6+ by oxidation of Fe2+ to Fe3+ using several periplasmic proteins encoded by the genes in rus and petI operons in its electron transport pathway. Accordingly, the purpose of this study was to consider the expression of these genes through exposed A. ferrooxidans sp. FJ2 to γ-ray in 17 different doses targeting uranium extraction yield. Acidithiobacillus ferrooxidans sp. FJ2 was irradiated by gamma rays at 25, 50, 75, 100, 150, 300, 450, 600, 750 Gy and 1, 2, 5, 10, 15, 20, 25 and 30 kGy doses. Moreover, the Eh value of 9k culture media was measured as special screening criteria to select the four treatments. The selected bacteria were cultured in 9k media, containing 50% uranium ore powder in the bioleaching process. Then, the value of pH & Eh of culture media, Fe2+ and uranium concentrations in 4, 8 and 13 day's period of incubation were measured. In followings, the expression levels of cyc1, cyc2, rus, coxB, petA, petB, petC and cycA genes at the end of each period were investigated by real-time PCR. Overall, all samples demonstrated a decrease in pH value and Fe2+ concentration and an increase in Eh value and U concentration in time intervals. The gamma irradiation in given doses raised the expression levels of all genes encoded in rus and petI operons, except petB gene during the bioleaching process, although, it had no effect either on the pH, Eh values or on Fe2+ and uranium concentrations. This result implies that during the oxidation of ferrous iron and formation of Jarosite sediment, the decreasing trend of pH and the increasing trend of Eh occurred in all samples. However, the differences in expression of the genes of rus and petI operons in the samples did not have an effect on uranium extraction.

Sonochemical recovery of uranium from nanosilica-based sorbent and its biohybrid.

Use of nanomaterials to remove uranium by adsorption from nuclear wastewater is widely applied, though not much work is focused on the recovery of uranium from the sorbents. The present work reports the recovery of adsorbed uranium from the microstructures of silica nanoparticles (SiO2M) and its functionalized biohybrid (fBHM), synthesized with Streptococcus lactis cells and SiO2M, intensified using ultrasound. Effects of temperature, concentration of leachant (nitric acid), sonic intensity, and operating frequency on the recovery as well as kinetics of recovery were thoroughly studied. A comparison with the silent operation demonstrated five and two fold increase due to the use of ultrasound under optimum conditions in the dissolution from SiO2M and fBHM respectively. Results of the subsequent adsorption studies using both the sorbents after sonochemical desorption have also been presented with an aim of checking the efficacy of reusing the adsorbent back in wastewater treatment. The SiO2M and fBHM adsorbed 69% and 67% of uranium respectively in the second cycle. The adsorption capacity of fBHM was found to reduce from 92% in the first cycle to 67% due to loss of adsorption sites in the acid treatment. Recovery and reuse of both the nuclear material and the sorbent (with some make up or activation) would ensure an effective nuclear remediation technique, catering to UN's Sustainable Development Goals.

Selective uptake of thorium(IV) from nitric acid medium using two extraction chromatographic resins based on diglycolamide-calix[4]arenes: Application to thorium-uranyl separation in an actual sample.

Two novel extraction chromatography resins (ECRs) containing two diglycolamide (DGA) -functionalized calix[4]arenes with n-propyl and isopentyl substituents at the amide nitrogen atom, termed as ECR-1 and ECR-2, respectively, were evaluated for the uptake of Th(IV) from nitric acid feed solutions. While both the resins were having a quite high Th(IV) uptake ability (Kd >3000 at 3 M HNO3), the uptake was relatively lower with the resin containing the isopentyl DGA, which appeared magnified at lower nitric acid concentrations. Kinetic modeling of the sorption data suggested fitting to the pseudo-second order model pointing to a chemical reaction during the uptake of the metal ion. Sorption isotherm studies were carried out showing a good fitting to the Langmuir and D-R isotherm models, suggesting the uptake conforming to monolayer sorption and a chemisorption model. Glass columns with a bed volume of ca. 2.5 mL containing ca. 0.5 g lots of the ECRs were used for studies to assess the possibility of actual applications of the ECRs. Breakthrough profiles obtained with feed containing 0.7 g/L Th(NO3)3 solution resulted in breakthrough volumes of 8 and 5 mL, respectively, for the ECR-1 and ECR-2 resins. Near quantitative elution of the loaded metal ion was possible using a solution of oxalic acid and nitric acid. A method for the separation of Th-234 from natural uranium was demonstrated for the possible application of ECR-1.

Effect of early whole lung lavage at different time-points for promoting the removal of depleted uranium from the lung.

PURPOSE: This study compared the effect of whole lung lavage (WLL) at different time-points early after exposure of the respiratory system to insoluble radioactive particles. MATERIALS AND METHODS: Forty adult beagles were randomized into a control group and the 3-h, 8-h, 24-h, and 48-h lavage groups (n = 8). A canine model of acute lung injury was established by spraying a depleted uranium (DU) suspension using a superfine fiber bronchoscope, at a dose of 20 mg/kg. The lavage groups were subjected to WLL at 3 h, 8 h, 24 h, and 48 h post-DU exposure, while the control group received no treatment after exposure. Measurement of U in serum was performed using inductively coupled plasma mass spectrometry; measurements in the lavage fluid and left lung tissue were performed using inductively coupled plasma atomic emission spectrometry. The color of the lavage fluid was analyzed using colorimetry, and shadow changes in the lung were observed using chest computed tomography (CT). RESULTS: The lavage groups showed similarly increasing trends for serum U levels from DU exposure to 3 and 7 days after exposure; however, these values were significantly lower than those in the control group (p < .01). The U content in the lavage fluid was significantly higher in the 3-h group than in the 8-h, 24-h, and 48-h groups (p < .01), while that in the 8-h group was markedly higher than those in the 24-h and 48-h groups (p < .05). The average clearance rate of DU in the lungs varied in the range of 0.63‒7.06%. The U content in the left lung tissue of each lavage group was significantly lower than that in the control group (p < .01), while the content in the 8-h, 24-h, and 48-h groups was significantly higher than that in the 3-h group (p < .05). The colorimetric score of the lavage fluid in the 3-h group was significantly lower than those in the 8-h, 24-h, and 48-h groups (p < .05). Chest CT showed different degrees of consolidation and ground glass shadow changes in all groups. The score of the left lung shadow volume in the 3-h group was significantly lower than in the control, 8-h, 24-h, and 48-h groups (p < .01), while the score in the 8-h group was significantly higher than those in the 48-h and control groups (p < .05). CONCLUSIONS: The best effect of WLL after exposure of the respiratory system to insoluble radioactive particles was achieved at 3 h, followed by 8 h; there was no difference in the effectiveness of lung lavage at 24 h and 48 h.

Nanocellulose aerogel for highly efficient adsorption of uranium (VI) from aqueous solution.

Cellulose nanofibers (CNFs) aerogel was prepared via simple covalent crosslinking and freeze-drying method. The porous cellulose aerogel possessed high specific surface area and high metal-chelating capacity, which showed fast adsorption kinetics and high adsorption capacity (440.60 mg g-1) in static uranium adsorption process. In the dynamic filtration system, the maximum adsorption capacity reached 194 mg g-1 with the initial concentration of 10 mg L-1. In addition, the CNFs aerogel possessed excellent selectivity and good regeneration ability for uranium adsorption. The integrated analyses of attenuated total reflection Fourier transform infrared (ATR-FTIR), X-Ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) suggested that the predominant UO22+ species formed inner-sphere surface complexes with two active carboxyl groups in the coordination model. This strategy may provide a sustainable route for development of efficient biomass-based adsorbents for selective uranium removal from aqueous solution.

Antibiofouling Ultrathin Poly(amidoxime) Membrane for Enhanced U(VI) Recovery from Wastewater and Seawater.

Although eco-friendly amidoxime-based adsorbents own an excellent uranium (U)-adsorption capacity, their U-adsorption efficiency is commonly reduced and even damaged by the biological adhesion from bacteria/microorganisms in an aqueous environment. Herein, we present an antibiofouling ultrathin poly(amidoxime) membrane (AUPM) with highly enhanced U-adsorption performance, through dispersing the quaternized chitosan (Q-CS) and poly(amidoxime) in a cross-linked sulfonated cellulose nanocrystals (S-CNC) network. The cross-linked S-CNC not only can elevate the hydrophilicity to improve the U-adsorption efficiency of AUPM but also can enhance the mechanical strength to form a self-supporting ultrathin membrane (17.21 MPa, 10 µm thickness). More importantly, this AUPM owns a good antibiofouling property, owing to the broad-spectrum antibacterial quaternary ammonium groups of the Q-CS. As a result, within the 1.00 L of low-concentration (100 ppb) U-added pure water (pH ≈ 5) and seawater (pH ≈ 8) for 48 h, 30 mg of AUPM can recover 93.7% U and 91.4% U, respectively. Furthermore, compared with the U-absorption capacity of a blank membrane without the Q-CS, that of AUPM can significantly increase 37.4% reaching from 6.39 to 8.78 mg/g after being in natural seawater for only 25 d. Additionally, this AUPM can still maintain almost constant tensile strength during 10 cycles of adsorption-desorption, which indicates the relatively long-term usability of AUPM. This AUPM will be a promising candidate for highly efficient and large-scale U-recovery from both U-containing waste freshwater/seawater and natural seawater, which will be greatly helpful to deal with the U-pollution and enrich U for the consumption of nuclear power. More importantly, the work will provide a new convenient but universal strategy to fabricate new highly enhanced low-cost U-adsorbents, through the introduction of both an antibacterial property and a high mechanical performance, which will be a good reference for the design of new highly efficient U-adsorbents.

A new method for the preconcentrations of U(VI) and Th(IV) by magnetized thermophilic bacteria as a novel biosorbent.

This paper proposes the use of Anoxybacillus flavithermus SO-15 immobilized on iron oxide nanoparticles (NPs) as a novel magnetized biosorbent for the preconcentrations of uranium (U) and thorium (Th). The SPE procedure was based on biosorption of U(VI) and Th(IV) on a column of iron oxide NPs loaded with dead and dried thermophilic bacterial biomass prior to U(VI) and Th(IV) measurements by ICP-OES. The biosorbent characteristicswere explored using FT-IR, SEM, and EDX. Significant operational factors such as solution pH, volume and flow rate of the sample solution, amounts of dead bacteria and iron oxide nanoparticles, matrix interference effect, eluent type, and repeating use of the biosorbent on process yield were studied. The biosorption capacities were found as 62.7 and 56.4 mg g-1 for U(VI) and Th(IV), respectively. The novel extraction process has been successfullyapplied to the tap, river, and lake water samples for preconcentrations of U(VI) and Th(IV).

Uptake and Removal of Uranium by and from Human Teeth.

Uranium-238 (238U), a long-lived radiometal, is widespread in the environment because of both naturally occurring processes and anthropogenic processes. The ingestion or inhalation of large amounts of U is a major threat to humans, and its toxicity is considered mostly chemical rather than radiological. Therefore, a way to remove uranium ingested by humans from uranium-contaminated water or from the air is critically needed. This study investigated the uranium uptake by hydroxyapatite (HAP), a compound found in human bone and teeth. The uptake of U by teeth is a result of U transport as dissolved uranyl (UO22+) in contaminated water, and U adsorption has been linked to delays in both tooth eruption and development. In this present work, the influence of pH, contact time, initial U concentration, and buffer solution on the uptake and removal of U in synthetic HAP was investigated and modeled. The influence of pH (pH of human saliva, 6.7-7.4) on the uptake of uranyl was negligible. Furthermore, the kinetics were extremely fast; in one second of exposure, 98% of uranyl was uptaken by HAP. The uptake followed pseudo-second-order kinetics and a Freundlich isotherm model. A 0.2 M sodium carbonate solution removed all the uranyl from HAP after 1 h. Another series of in vitro tests were performed with real teeth as targets. We found that, for a 50 mg/L U in PBS solution adjusted to physiological pH, ∼35% of the uranyl was uptaken by the tooth after 1 h, following pseudo-first-order kinetics. Among several washing solutions tested, a commercially available carbonate, as well as a commercially available fluoride solution, enabled removal of all the uranyl taken up by the teeth.

Actinide ion uptake from acidic radioactive feeds using an extraction chromatographic resin containing a branched dialkyl amide.

A dialkyl amide with branched alkyl group, viz. N,N-di(2-ethylhexyl)-propionamide (D2EHPrA) was used as the organic extractant in an extraction chromatographic resin prepared for the first time and evaluated for the separation of uranium from acidic feeds. The distribution coefficient measurements, carried out at varying HNO3 concentrations, indicated an increase in the UO22+ ion sorption with increasing nitric acid concentration. The UO22+ ion sorption kinetics and sorption isotherms with this resin were investigated in details. The column studies indicated that 8.3 mg of uranium could be loaded on a 2.1 cm3 column bed volume containing 0.35 g resin. Batch distribution data for other actinides such as Np4+ and Pu4+ indicated that the resin can also be used for effective separation of these metal ions from acidic feeds. Though the resin showed effectiveness for Np and Pu, detailed investigations dealing with macro concentrations of metal ions (in gm quantities) were restricted to uranium only due to hazardous nature of plutonium and limited availability of neptunium. The encouraging results reported in this work is an indication of the possible application of this resin for the recovery or pre-concentration of UO22+, Np4+ and Pu4+ ions from large volumes of aqueous solutions of moderate acidity.

DNA nano-pocket for ultra-selective uranyl extraction from seawater.

Extraction of uranium from seawater is critical for the sustainable development of nuclear energy. However, the currently available uranium adsorbents are hampered by co-existing metal ion interference. DNAzymes exhibit high selectivity to specific metal ions, yet there is no DNA-based adsorbent for extraction of soluble minerals from seawater. Herein, the uranyl-binding DNA strand from the DNAzyme is polymerized into DNA-based uranium extraction hydrogel (DNA-UEH) that exhibits a high uranium adsorption capacity of 6.06 mg g-1 with 18.95 times high selectivity for uranium against vanadium in natural seawater. The uranium is found to be bound by oxygen atoms from the phosphate groups and the carbonyl groups, which formed the specific nano-pocket that empowers DNA-UEH with high selectivity and high binding affinity. This study both provides an adsorbent for uranium extraction from seawater and broadens the application of DNA for being used in recovery of high-value soluble minerals from seawater.

Structure and gene cluster of the O-polysaccharide from Pseudomonas veronii A-6-5 and its uranium bonding.

A denitrifying bacterium Pseudomonas veronii A-6-5 was isolated from a deep aquifer contaminated with nitrates and uranium. The O-polysaccharide (OPS) was isolated by mild acid degradation of the lipopolysaccharide of P. veronii A-6-5 and studied using sugar analysis and 1D and 2D 1H and 13C NMR spectroscopy. The trisaccharide O-repeating unit was found to have the following structure: [Formula: see text] [Formula: see text] where Hb is 3-hydroxybutanoyl. The genome of P. veronii A-6-5 was sequenced and a respective OPS gene cluster was identified. Functions of the proteins encoded in the gene cluster, including the enzymes involved in the O-polysaccharide biosynthesis and glycosyl transferases, were putatively assigned by comparison with available database sequences. Formation of a new coordination bond between uranyl and the O-polysaccharide from P. veronii A-6-5 was demonstrated using FTIR spectroscopy; it may affect uranyl migration in the groundwaters due to its immobilization on microbial biofilms. Applied importance of this work is that the structure of the O-polysaccharide of a strain isolated from uranium-contaminated groundwater was determined and the character of interaction between the polysaccharide and the uranyl ion was established. The data obtained are of importance for development of the biotechnologies for treatment of uranium-contaminated groundwater and activated sludge.

Facile modification of graphene oxide and its application for the aqueous uranyl ion sequestration: Insights on the mechanism.

Graphene oxide (GO) has been proved with favorable affinity to U(VI), while some drawbacks such as poor dispersity and low adsorption performance limit its application. Herein, cetyltrimethylammonium bromide (CTAB) modified graphene oxide (MGO) composites were successfully fabricated, characterized and compared with graphene oxide (GO) in the sequestration of U(VI) in aqueous solutions. The results showed that maximum adsorption rate of MGO (99.21%) was obviously higher than that of GO (66.51%) under the same initial condition. Simultaneous introduction of C-H and NO coupled with the enhanced dispersity of GO after modification were mainly responsible for the updated performance verified with multiple characterization techniques. Based on the results of kinetics and isotherms investigations, the experimental data were best described by Pseudo-first-order kinetic model and Redlich-Peterson isotherm model. The results of ΔH, ΔS and ΔG show that adsorptive behaviors of uranyl ion on MGO are endothermic and spontaneous. The study provides a feasible alternative to the chemical modification of GO and enhancing the performance towards uranyl ion removal from solution.

Bioremediation of water contaminated with uranium using Penicillium piscarium.

Penicillium piscarium can be indicated as promising in the treatment of sites contaminated with uranium. Thus, this research aimed to analyze the P. piscarium dead biomass in uranium biosorption. This fungus was previously isolated from a highly contaminated uranium mine located in Brazil. Biosorption tests were carried out at pH 3.5 and 5.5 in solutions contaminated with concentrations of 1 to 100 mg/L of uranium nitrate. Our results showed that the dead biomass of P. piscarium was able to remove between 93.2 and 97.5% uranium from solutions at pH 3.5, at the end of the experiment, the pH of the solution increased to values above 5.6. Regarding the experiments carried out in solutions with pH 5.5, the dead biomass of the fungus was also able to remove between 38 and 92% uranium from the solution, at the end of the experiment, the pH of the solution increased to levels above 6.5. The analysis of electron microscopy, Energy-dispersive spectroscopy, and X-ray fluorescence demonstrated the high concentration of uranium precipitated on the surface of the fungal biomass. These results were impressive and demonstrate that the dead biomass of P. piscarium can be an important alternative to conventional processes for treating water contaminated with heavy metals, and we hope that these ecofriendly, inexpensive, and effective technologies be encouraged for the safe discharge of water from industrial activities.

Quantification of U, Th and specific radionuclides in coal from selected coal fired power plants in South Africa.

Most of South Africa's energy is derived from the combustion of coal in pulverized coal-fired power plants (CFPP). However, when compared with the rest of the world, limited information regarding the main radioactive elements (U and Th) and specific radionuclides of interest (K40, Ra226 and Th232) from South African CFPP is available in the public domain. This paper aims to quantify the U, Th and specific radionuclides found in the coal used in selected South African CFPP in comparison to world averages found in literature. The U and Th concentrations were obtained by ICP-MS. The main radionuclides, K40, Ra226 and Th238, were quantified using gamma spectrometry. The U concentration and Th concentrations for the coal used in all the power plants was above the world average of 1.9 mg/kg and 3.2 mg/kg respectively. The coals with the highest Th content originated from the Mpumalanga power plant, while the U content in the Freestate power plant samples was the highest of the three. The concentrations of the K40 were between 88.43±10.75-110.76±8.92 Bq/kg, which are in-line with world averages of 4-785 Bq/kg. Similarly, the Ra226 and Th232 values were between 21.69±2.83-52.63±4.04 Bq/kg and 19.91±1.24-22.97±1.75 Bq/kg respectively, which are also in line with the world averages of 1-206 Bq/kg and 1-170 Bq/kg respectively. Radiological hazard indices such as radium equivalent (Raeq); external hazard index (Hex) and internal hazard index (Hin), that were estimated from these average radionuclide concentrations were less than the prescribed values found in literature. This indicated that no significant health risk was posed by the coal being used from these coal fields.

Marinobacter sp. Stable Hydrous Titanium Oxide-Functionalized Bovine Serum Albumin Nanospheres for Uranium Capture from Spiked Seawater.

A novel nanospherical hydrous titanium oxide adsorbent (hydrous titanium oxide-immobilized bovine serum albumin nanospheres, HTO-BSA-NSs) was prepared by immobilizing HTOs with a manipulated molecular mass and number of active sites for uranium on the surface of BSA-NSs. The adsorption performances of HTO-BSA-NSs were investigated in spiked natural seawater with extra 8 ppm uranium. The results demonstrated that HTO-BSA-NSs are capable of uranium capture from a complex aqueous matrix with a low uranium concentration. Meanwhile, the microbial stability of HTO-BSA-NSs in sterilized natural seawater with Marinobacter sp. was investigated and observed through an optical microscope and TEM, revealing that the wrapped HTOs could protect the BSA-NSs from the decomposition of microorganisms, and the structure and functional groups of HTO-BSA-NSs remain stable compared with the BSA-NSs. In addition, the uranium adsorption mechanism of HTO-BSA-NSs is mainly recognized as dehydrated complexation, which was concluded from characterization analysis, adsorption model fitting, and theoretical calculations based on density functional theory. The remarkable uranium adsorption performance and microbial stability of HTO-BSA-NSs indicated that they have the potential to be a low-cost and environmentally friendly adsorbent for uranium extraction from complex environments such as seawater or uranium-containing industrial wastewater.

Separation of Uranium and Thorium for 230Th-U Dating of Submarine Hydrothermal Sulfides.

The age of a submarine hydrothermal sulfide is a significant index for estimating the size of hydrothermal ore deposits. Uranium and thorium isotopes in the samples can be separated for 230Th-U dating. This article presents a method to purify and separate U and Th isotopes in submarine hydrothermal sulfide samples. Following this technique, the separated U and Th fractions can meet measuring requirements by multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS). The age of the hydrothermal sulfide sample can be calculated by measuring the present-day activity ratios of 230Th/238U and 234U/238U. A super clean room is necessary for this experiment. Cleaned regents and supplies are used to reduce the contamination during the sample processes. Balance, hotplate, and centrifuge are also used. The sulfide sample is powdered for analysis and less than 0.2 g sample is used. Briefly, the sample is weighed, dissolved, added to 229Th-233U-236U double spike solution, Fe co-precipitated, and separated on an anion-exchange resin extraction column. Approximately 50 ng U is consumed for 230Th-U dating of sulfides sample by MC-ICPMS.

3-Hydroxy-2-Pyrrolidinone as a Potential Bidentate Ligand for in Vivo Chelation of Uranyl with Low Cytotoxicity and Moderate Decorporation Efficacy: A Solution Thermodynamics, Structural Chemistry, and in Vivo Uranyl Removal Survey.

Uranium poses a threat for severe renal and bone damage in vivo. With the rapid development of nuclear industry, it is more urgent than ever to search for potential in vivo uranium chelators. In this work, 3-hydroxy-2-pyrrolidinone (HPD) is investigated as a new potential uranium decorporation ligand. The potentiometric titration measurements were carried out, and the stability constants were determined to be log ß110 = 10.5(7), log ß120 = 20.7(9), and log ß130 = 28.2(4). The species distribution diagram shows that nearly all uranyl is complexed by HPD at pH 7.4 under the defined condition. A single crystal of uranyl and HPD complexes, [(UO2)3O(H2O)3(C4H6NO2)3]·NO3·12H2O (uranyl-HPD), was obtained via an evaporation method. The overall structure of uranyl-HPD is a trimer that consists of three uranyl units and three HPD ligands. The uranyl unit is equatorially coordinated by three oxygen atoms from two HPD agents, one coordinated water molecule, and one µ3-O atom that is shared by three uranyl units. The results of the cytotoxicity assay indicate that the ligand is less toxic than the chelators used clinically (i.e., DTPA-ZnNa3 and 3-hydroxy-1,2-dimethyl-4(1 H)-pyridone (DFP)). The results of the uranium removal assay using the NRK-52E cell show that it could reduce as much as 58% of the uranium content at the cellular level. Furthermore, the in vivo uranium decorporation assays demonstrate that HPD can remove 52% of uranium deposited in the kidney but shows poor uranium removal efficacy in the bone.

MnO2-loaded microorganism-derived carbon for U(VI) adsorption from aqueous solution.

A low-cost industrial microorganism, Saccharomyces cerevisiae, was employed as a precursor to synthesize carbon/MnO2 composites (MMCs) via an oxidation-reduction reaction and one-step carbonization method for U(VI) adsorption. Scanning electron microscopy and nitrogen adsorption measurement indicated that the microorganism's carbonization could form surface porous structure and increase the specific surface area. Batch experiments showed that the maximum U(VI) adsorption capacity of MMCs reached 207 mg g-1 at [U(VI)]initial = 25 mg L-1 and pHinitial = 4.5. The obtained thermodynamic and kinetic parameters suggested that the process is endothermic, spontaneous, and chemisorption. FTIR and X-ray photoelectron spectroscopy demonstrated that the surface hydroxyl groups of composites might be the reactive adsorption sites for U(VI). Additionally, 0.5 mol L-1 HNO3 solution could desorb ~ 95% uranium from U(VI)-loaded MMCs, and materials exhibited good regenerated availability. This study suggests that MMCs can be a potential adsorbent for U(VI) preconcentration and removal from radioactive wastewater.