Uranyl arsenate minerals,which exhibit low solubility,serve as major sinks for U and As,playing a crucial role in controlling the mobility of U and As in the environment.However,the specific mechanisms underly-ing the...Uranyl arsenate minerals,which exhibit low solubility,serve as major sinks for U and As,playing a crucial role in controlling the mobility of U and As in the environment.However,the specific mechanisms underly-ing the formation of uranyl arsenate minerals have remained largely elusive.Herein,the formation pathway of the non-charged UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 complex was investigated to elucidate the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral(where n represents the stoichiometric number of H_(2)O),a representative uranyl arsenate mineral.Based on the combination experiments of U(VI)and As(V),our findings underscore the sig-nificant dependence of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 formation on solution pH(4.0–10.0).Density functional theory(DFT)calculations reveal a two-step reaction involving two distinct pathways(Pathway 1 and Pathway 2)for the formation of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O,and the intermediate was confirmed by in situ Raman and fluorescence spec-troscopy.Specifically,the hydroxyl‑connected uranyl(UO_(2)OH^(+))reacts with the protonated arsenate(H_(2)AsO_(4)^(-))species to form the intermediate UO_(2)HAsO4·H_(2)O(Pathway 1)or UO_(2)OH–H2AsO4(Pathway 2)with a U/As ratio of 1:1.Meanwhile,all the transition states also were obtained and the energy barrier suggested that the UO_(2)(H_(2)AsO_(4))_(2)·2H_(2)O0 formed by Pathway 1 is thermodynamically favored over Pathway 2,and may serve as the primary fundamental structural unit or precursor for the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral phase.Altogether,this study contributes to advancing the understanding of the formation of uranyl arsenate min-erals at the molecular scale and provides a theoretical basis for predicting and regulating uranium and arsenic mobilization in their coexisting environment.展开更多
The crystal structure of Di-nitratobis(ethylcaprolactam)uranyl(Ⅱ) UO_2[CH_2(CH_2)_4CONC_2H_5]_2(NO_3)_2 was established by a single-crystal X-ray diffraction study.It is triclinie, space group P1, with a=7.171(2), b=...The crystal structure of Di-nitratobis(ethylcaprolactam)uranyl(Ⅱ) UO_2[CH_2(CH_2)_4CONC_2H_5]_2(NO_3)_2 was established by a single-crystal X-ray diffraction study.It is triclinie, space group P1, with a=7.171(2), b=8.655(3), c=10.182(5)A, α=78.27(3), β=70.63(3), γ=81.76(3)°, V=581.7(4)A^3, Z=l, Dc=1.94 g.cm^(-3).Final R value is 0.0218.The result reveals that uranyl ion is coordinated to six oxygen atoms, two of them are from two carbonyl groups of ethylcaprolactam and the other four are from two nitrate groups.展开更多
In this study,we present a self-driven photoelectrocatalytic(SD-PEC)system that effectively treats complex uranium-bearing wastewaters for both uranium recovery and organic matter decomposition while generating power....In this study,we present a self-driven photoelectrocatalytic(SD-PEC)system that effectively treats complex uranium-bearing wastewaters for both uranium recovery and organic matter decomposition while generating power.The system utilizes a titanium dioxide nanorod array(TNR)photoelectrode coupled with a silicon solar cell to optimize electron transport,while the cathode is composed of a carbon fiber coated with carboxylated carbon nanotubes(CCNT/CF),which efficiently reduce UO_(2)^(2+).The results demonstrate significant removal efficiency of uranium(complete removal in 25 min at a rate constant of~0.248 min^(-1)),as well as substantial degradation of organic impurities.Furthermore,the system generates sufficient power output to light an LED lamp and exhibits superior performance under various complex wastewater conditions,including simulated seawater and real uranium tailings wastewater.These findings underscore the potential of the SD-PEC system as a versatile approach for sustainable treatment and energy recovery of radioactive wastewater.The significance of this research extends to global environmental challenges,offering an innovative solution for managing radioactive wastewater while simultaneously contributing to renewable energy generation.展开更多
Uranyl （VI） amidoxime complexes are investigated using relativistic density functional theory. The equilibrium structures, bond orders, and Mulliken populations of the complexes have been systematically investigated...Uranyl （VI） amidoxime complexes are investigated using relativistic density functional theory. The equilibrium structures, bond orders, and Mulliken populations of the complexes have been systematically investigated under a generalized gradient approximation （GGA）. Comparison of （acet） uranyl amidoxime complexes （[UO2（AO）n]2-n, 1≤ n≤4） with available experimental data shows an excellent agreement. In addition, the U-O（1）, U-O（3）, C（1）-N（2）, and C（3） N（4） bond lengths of [UO2（CH3AO）4]2- are longer than experimental data by about 0.088, 0.05, 0.1, and 0.056 A. The angles of N（3） O（3）-U, O（2）-N（1）-C（1）, N（3）-C（3）-N（4）, N（4）-C（3） C（4）, and C（4）-C（3）-N（3） are different from each other, which is due to existing interaction between oxygen in uranyl and hydrogen in amino group. This interaction is found to be intra-molecular hydrogen bond. Studies on the bond orders, Mulliken charges, and Mulliken populations demonstrate that uranyl oxo group functions as hydrogen-bond acceptors and H atoms in ligands act as hydrogen-bond donors forming hydrogen bonds within the complex.展开更多
An acrylic modified pumpkin vine-based biochar(p-PVB-PAA) is synthesized by non-thermal plasma-grafting modification of pumpkin vine-based biochar(PVB) for the removal of uranyl from an aqueous solution. Microscopic c...An acrylic modified pumpkin vine-based biochar(p-PVB-PAA) is synthesized by non-thermal plasma-grafting modification of pumpkin vine-based biochar(PVB) for the removal of uranyl from an aqueous solution. Microscopic characterization reveals that compared to PVB the surface of p-PVBPAA has more oxygen-containing functional groups by strong chemical bonding and the specific surface area is increased to 275.3 m^2 g^-1 from 3.8 m^2g^-1. It is found that p-PVB-PAA showed a much higher maximum adsorption capacity for uranyl from aqueous solutions than PVB, which were207.02 mg g^-1 and 67.58 mg g^-1 at pH=5 and 298 K, respectively. Moreover, the adsorption behavior follows a pseudo-second-order kinetics model and the Langmuir adsorption model.Additionally, macroscopic experiments and spectroscopic studies verified that the significantly improved adsorption performance of the p-PVB-PAA is due to surface complexation and electrostatic interactions. Furthermore, the very high removal efficiency and excellent regeneration ability(the percentage of the removal still remained at nearly 90% after five cycles) makes this low-cost, easily obtained, and environmentally friendly material attractive for commercial application.展开更多
The adsorption of uranyl on hydroxylated α-SiO_2(001) in the presence of a series of anionic ligands, i.e. OH^-, CO_3^(2-), NO_3^-, H_2PO_4^-, HPO_4^(2-),CH_3COO^-(Ac^-), C_6H_5COO^-(PhCO_2^-), C_6H_5O^-(PhO^-), was ...The adsorption of uranyl on hydroxylated α-SiO_2(001) in the presence of a series of anionic ligands, i.e. OH^-, CO_3^(2-), NO_3^-, H_2PO_4^-, HPO_4^(2-),CH_3COO^-(Ac^-), C_6H_5COO^-(PhCO_2^-), C_6H_5O^-(PhO^-), was studied by the periodic density functional theory(DFT) implemented in the Vienna ab initio simulation package(VASP). For the ligands other than OH^-and PhO^-, only the bidentate coordination modes to the uranyl were considered. The excess charge effect of a charged system was first evaluated by constructing models with net charge as is or neutralized by creating defect at the bottom of silica, and the results show that a neutralized model, even with defects, is more realistic than the charged ones.All uranyl species prefer to bind with the deprotonated site(—O^-) rather than the protonated one(—O_H), which suggests that the increase of pH,which leads to the deprotonation of the surface, may enhance the uranyl adsorption. On the other hand, the anionic ligands, which are formed at higher pH, have negative effects. The weaker acidic ligands, such as H_2CO_3, H_3PO_4 and H_2O, whose speciation in solutions is sensitive to the fluctuation of pH, have more complex effect on the uranyl adsorption than strong acids or bases. Humic substances may coordinate with uranyl through carboxyl and phenolic groups, with the carboxyl group bound stronger. The ternary complexes with one bidentate(or monodentate)anion and one(or two) H20 as ligands, which leads to the uranyl penta-coordinated in its equatorial plane, are more favorable than other configurations when bound to the same anionic ligand. Both the charged nature and the coordination behavior of an anionic ligand are relevant to its ability to influence the adsorption of uranyl on the mineral surface. In addition, the uranyl species adsorbed at the surface functionalized by anionic ligands were also addressed, and the functionalized surfaces have weaker interaction with hydrated uranyl dication.展开更多
Black precipitates were successfully obtained by radiolytic reduction of ammonium uranyl tricarbonate in the aqueous solution of HCOONH_4 by one step.TEM,SAED,EDS,and XRD analysis indicated that the precipitates consi...Black precipitates were successfully obtained by radiolytic reduction of ammonium uranyl tricarbonate in the aqueous solution of HCOONH_4 by one step.TEM,SAED,EDS,and XRD analysis indicated that the precipitates consist of hollow UO2 nanospheres（φ：30-50 nm,wall thickness：8-15 nm,and cavity diameter：10-20 nm）.The effect of HCOONH4 concentration,irradiation time and dose rate on the morphology,and size of nanospheres was investigated.Then,a gas-bubble template mechanism was proposed.展开更多
The new uranyl complex UO2(NO3)2[PhN(CH3)C(O)(CH3)NPh]2 was synthesized and its crystal structure has been determined by single-crystal X-ray diffraction. Crystal data: C30H32N6O10U, triclinic, space group P with a = ...The new uranyl complex UO2(NO3)2[PhN(CH3)C(O)(CH3)NPh]2 was synthesized and its crystal structure has been determined by single-crystal X-ray diffraction. Crystal data: C30H32N6O10U, triclinic, space group P with a = 7.772(1), b = 9.267(1), c = 12.644(1) ? a = 68.246(8), b = 73.871(9), g = 84.99(1)o, V = 812.4(2) ?, Mr = 874.65, Z = 1, Dc = 1.788 g/cm3, F(000) = 426, m = 5.062 mm-1, the final R = 0.022 and wR = 0.059 for 3571 observed reflections (I > 2s(I)). The central uranyl ion is coordinated by six oxygen atoms, two from the carbonyl groups of N,N-dimethyl-N,N-dibenzenyl-urea molecules and the other four from two nitrate groups.展开更多
Hydrothermal reactions of uranyl nitrate and 4,4＇-oxidiphthalic acid（H4L） resulted in the formation of three new uranyl-organic framework materials,namely（NH4）2[（UO2）3（L）2]·5H2O（1）,（NEt4）[（UO2）3（...Hydrothermal reactions of uranyl nitrate and 4,4＇-oxidiphthalic acid（H4L） resulted in the formation of three new uranyl-organic framework materials,namely（NH4）2[（UO2）3（L）2]·5H2O（1）,（NEt4）[（UO2）3（H2O）（L）（HL）]（2） and（UO2）7（H2O）2（phen）4（L）2（HL）2（3）（NEt4 = tetraethylammonium,phen = 1,10-phenanthroline）.These three structures all comprise common uranyl pentagonal bipyramids.In 1,UO7polyhedra are linked by hexadentate ligands to form a 3D framework with 1D channels,in which are located NH4^＋ ions and water molecules.While in 2,the organic ligands adopt pentadentate and hexadentate coordination modes,ligating UO7 units to create a layered structure with channels filled by NEt4^＋ ions.For 3,uranyl square bipyramids are also accommodated together with pentagonal bipyramids,which are linked by tetradentate carboxylate ligands to produce the layered assembly.Phen molecules also coordinate to the uranyl centers to build up the structure.Luminescent studies indicate that 2 and 3 exhibit the characteristic uranyl emission.展开更多
We use molecular dynamics simulation to study the mechanisms involved in the adsorption of aqueous uranyl species(UO_2^(2+)) to the basal surfaces of clay minerals,including kaolinite,pyrophyllite and montmorillonite....We use molecular dynamics simulation to study the mechanisms involved in the adsorption of aqueous uranyl species(UO_2^(2+)) to the basal surfaces of clay minerals,including kaolinite,pyrophyllite and montmorillonite.Uranyl ion can form various complexes with carbonates,namely,[UO_2(H_2O)_5]^(2+),[UO_2(H_2O)3(CO_3)],[UO_2(H_2O)2(CO_3)_2]^(2-),[UO_2(CO_3)_3]^(4-).The simulations show that at aqueous clay interfaces,both uranyl species and surface type control the adsorption pattern.The noncarbonato and monocarbonato uranyl species can form outer-sphere complexes on siloxane surfaces through electrostatic interaction,but the dicarbonato and tricarbonato uranyl complexes rarely adsorb on the siloxane surfaces.Strong outer-sphere adsorptions of the uranylcarbonate complexes on gibbsite surfaces are observed,which are fixed by hydrogen bonds between the ligands(carbonate and/or H_2O) and surface hydroxyls.The sorption behaviors derived in this study provide new insights into understanding the migration and enrichment of uranium and other radionuclides.展开更多
Amino-type adsorbents(ATAs) were prepared by radiation-induced graft copolymerization of 4-hydroxybutyl acry late glycidyl ether(HB) onto a polyethylene-coated polypropylene(PE/PP) duplex fiber of a non-woven fabric,a...Amino-type adsorbents(ATAs) were prepared by radiation-induced graft copolymerization of 4-hydroxybutyl acry late glycidyl ether(HB) onto a polyethylene-coated polypropylene(PE/PP) duplex fiber of a non-woven fabric,and modified with different amines of ethylenediamine(EDA),diethylenetriamine(DETA),triethylenetetramine(TETA) and diethylamine(DEA).The adsorption behavior of uranyl ions onto the ATAs was studied in batch experiments.The effects of the contact time,initial concentration of the ions,temperature,and pH value.The salinity were investigated along with the adsorption kinetics and the adsorption isotherms.The kinetic experimental data followed the pseudo second-order kinetic model,and the adsorption isotherms correlated well with the Langmuir model.The ATAs showed good efficiency in adsorbing uranyl ions,with the best saturation adsorption capacity being 64.26 mg g^(-1) for ATA-DETA within 120 min.The temperature dependence of ATADETA was quite abnormal and the quickest behavior was obtained at 25 ℃.ATAs showed good adsorption capacity over a wide pH range of 4.0-8.5,and HCl could be used in the elution process.Salinity of the solution had great effect on the adsorption capacity,3.5%salinity resulted in a 55%loss of capacity from ATA-DETA.The selectivity of ATA-DETA showed an order of:UO_2^(2+)≈Fe^(3+)> Zn^(2+) > VO_3^- > Co^(2+) > Ni^(2+).展开更多
With a heptadentate compartmental Schiff-base ligand H3L (1, 3-di[o-(salicylimino) ph- enoxyl]-2-propanol), a new binuclear diuranyl complex [(UO2)2L(OH)]?DMF, C38H45N5O13U2, was synthesized and the crystal structure ...With a heptadentate compartmental Schiff-base ligand H3L (1, 3-di[o-(salicylimino) ph- enoxyl]-2-propanol), a new binuclear diuranyl complex [(UO2)2L(OH)]?DMF, C38H45N5O13U2, was synthesized and the crystal structure was determined by X-ray diffraction techniques. The coordination geometry are two pentagonal bipyramids. In each pentagon four kinds of U-O (phenoxido, hydroxo, alkoxo and ether oxo) bonds are discussed.展开更多
The new uranyl complex UO2(NO3)2[C5H10NC(O)NH10C5]2 has been synthesized and its structure was determined by single-crystal X-ray diffraction. Crystal data: C22H40N6O10U, monoclinic, space group P21/c, a = 11.151(3)...The new uranyl complex UO2(NO3)2[C5H10NC(O)NH10C5]2 has been synthesized and its structure was determined by single-crystal X-ray diffraction. Crystal data: C22H40N6O10U, monoclinic, space group P21/c, a = 11.151(3), b = 13.907(3), c = 10.067(2) ?, β = 115.602(4)°, V = 1408.0(5) ?3, Mr = 786.63, Z = 2, Dc = 1.855 g/cm3, F(000) = 772, μ = 5.827 mm-1, R = 0.0465 and wR = 0.1065 for 2916 observed reflections (I > 2σ(I)). The central uranyl ion is coordinated by six oxygen atoms, of which two are from the carbonyl groups of di-piperidin-1-yl-methanone molecules and the other four from two nitrate groups.展开更多
An organically templated 2-D uranyl sulfate, {（C2H8N）[（UO2）Cl（SO4）（H2O）] }n 1, has been hydrothermally synthesized. The crystal and molecular structures have been determined by X-ray crystallography method and...An organically templated 2-D uranyl sulfate, {（C2H8N）[（UO2）Cl（SO4）（H2O）] }n 1, has been hydrothermally synthesized. The crystal and molecular structures have been determined by X-ray crystallography method and spectral techniques. 1 belongs to monoclinic, space group P21/c with a = 8.3545（17）, b = 10.550（2）, c = 12.370（3）A, β = 102.64（3）°, V = 1063.9（4）A3, Mr = 464.64, De= 2.901 g/cm^3, F（000） = 836,μ = 15.710 mm^-1, Z= 4, the final R = 0.0286 and wR = 0.0685 for 10164 observed reflections with Ⅰ 〉 2σ（Ⅰ）. 1 presents a two-dimensional layer-like structure constructed from infinite anionic [（UO2）Cl（H2O）（SO4）]^- layers with [C2H8N]^＋ cations balancing the charge and a number of intermoleeular hydrogen bonds （C-H…O and O-H…Cl） existing in the solid state. The fluorescence properties of 1 have also been discussed.展开更多
New solid complexes of europium, uranyl and zinc ions with N-oxides of 4-chloro-2,6-dimethylpyridine, quinoline and 4-meth- oxyquinaldinic acid in presence different anions were obtained and characterized by elemental...New solid complexes of europium, uranyl and zinc ions with N-oxides of 4-chloro-2,6-dimethylpyridine, quinoline and 4-meth- oxyquinaldinic acid in presence different anions were obtained and characterized by elemental and TG analyses, IR and luminescence spectra. The compounds are crystalline, hydrated or anhydrous salts with colours typical of metal ions. Thermal studies showed that in hydrated salts lattice or coordination water molecules are present. A role of different anions in the formation of various types of the complexes is presented.展开更多
In order to discover genes capable of catalyzing the reductive immobilization of toxic chromate and uranyl ions, we have created a T7 bacteriophage library containing cDNA from environmental microbes (i.e., Geobacter ...In order to discover genes capable of catalyzing the reductive immobilization of toxic chromate and uranyl ions, we have created a T7 bacteriophage library containing cDNA from environmental microbes (i.e., Geobacter sulfurreducens and Shewanella oneidensis MR-1) that are known to mediate the reduction of chromate and uranyl ions. After three rounds of screening, ten bacteriophage mutants were found to mediate the NADH-dependent reduction of chromate and uranyl ions whose cDNA encodes polypeptide chains ranging 14 to 73 amino acids in length. All identified sequences contain disordered structural motifs similar to the β-amyloid peptide (Aβ) known to promote aggregation and formation of high-affinity metal binding sites. Confirmation of this structural similarity involved phage display of the 42 amino-acid Aβ-peptides that have been found to catalyze the NADH-dependent reduction of both chromate and uranyl ions. Transmission electron microscopy (TEM) and X-ray absorption near edge structure (XANES) measurements confirm that reduced uranium is present on the surface of bacteriophage expressing the Aβ-peptide. The surface-displayed Aβ-like peptide on bacteriophage has the potential to couple naturally occurring electron transfer shuttles present in soils to promote economically viable remediation of contaminated sites containing toxic chromate and uranyl ions.展开更多
Under the public spotlight,uranyl(UO22+)ions has attracted considerable attention for the extreme radioactive and chemical toxicity to ourselves and our environment.Herein,we present a simple and effective ratiometric...Under the public spotlight,uranyl(UO22+)ions has attracted considerable attention for the extreme radioactive and chemical toxicity to ourselves and our environment.Herein,we present a simple and effective ratiometric fluorescence imaging method for the visualizing and quantitative detection UO22+ions by cellphone-based optical platform.The sensing solution was prepared by mixing label-free red carbon dots(r-CDs)and blue carbon dots(b-CDs)together with a fixed photoluminescence intensity ratio of 4:1.When UO22+ions were added,the fluorescence of r-CDs can be selectively quenched,while the fluorescence of b-CDs remains stable without spectral cha nges.With the gradually increase the amounts of UO22+ions,the different response of dual-color CDs resulted in a signification color evolution from deep red to dark purple under the ultraviolet(UV)light illumination.Then,a cellphone-based optical platform was constructed for directly imaging the color change of the samples,and the built-in Colorpicker APP quickly output the red,green and blue(RGB)channel values of these images within one second.Interesting,there was a linear relationship between the ratio of red and blue(R/B)channel values and UO22+ions concentration from 0μmol/L to 30.0μmol/L(R^2=0.92804)with the detection limit of^8.15μmol/L(signal-to-noise ratio of 3).In addition,the optical platform has also been applied to the quantification of UO22+ions in tap water and river water sample.With the advantage of low-cost,portable,easy to operation,we anticipate that this method would greatly improve the accessibility of UO22+ions detection even in resource-limited areas.展开更多
The crystal structure of the title compound UO2(NO3)2[CH2(CH2)2CONC8H17] was determined by single-crystal X-ray diffraction. Crystal data: triclinic, space group P , a = 7.456(2), b = 8.371(2), c = 13.470(3) ? ?= 95.6...The crystal structure of the title compound UO2(NO3)2[CH2(CH2)2CONC8H17] was determined by single-crystal X-ray diffraction. Crystal data: triclinic, space group P , a = 7.456(2), b = 8.371(2), c = 13.470(3) ? ?= 95.66(1), ?= 94.64(2), ?= 102.67(2), C24H46N4O10U, Mr = 788.68, V = 811.7(3) ?, Dc = 1.613 g/cm3, Z = 1, F(000) = 390, ?= 5.052 mm-1, the final R = 0.0256 and wR = 0.0568 for 2826 observed reflections (I > 2(I)). The central uranyl ions are coordinated by six oxygen atoms. Two of them are from the carbonyl groups of N-octyl-a-pyrrolidone molecules, and the other four from two nitrate groups.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U20A20267 and 22376223)Hunan Provincial Natural Science Foundation(No.2023JJ0065).
文摘Uranyl arsenate minerals,which exhibit low solubility,serve as major sinks for U and As,playing a crucial role in controlling the mobility of U and As in the environment.However,the specific mechanisms underly-ing the formation of uranyl arsenate minerals have remained largely elusive.Herein,the formation pathway of the non-charged UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 complex was investigated to elucidate the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral(where n represents the stoichiometric number of H_(2)O),a representative uranyl arsenate mineral.Based on the combination experiments of U(VI)and As(V),our findings underscore the sig-nificant dependence of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O0 formation on solution pH(4.0–10.0).Density functional theory(DFT)calculations reveal a two-step reaction involving two distinct pathways(Pathway 1 and Pathway 2)for the formation of UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O,and the intermediate was confirmed by in situ Raman and fluorescence spec-troscopy.Specifically,the hydroxyl‑connected uranyl(UO_(2)OH^(+))reacts with the protonated arsenate(H_(2)AsO_(4)^(-))species to form the intermediate UO_(2)HAsO4·H_(2)O(Pathway 1)or UO_(2)OH–H2AsO4(Pathway 2)with a U/As ratio of 1:1.Meanwhile,all the transition states also were obtained and the energy barrier suggested that the UO_(2)(H_(2)AsO_(4))_(2)·2H_(2)O0 formed by Pathway 1 is thermodynamically favored over Pathway 2,and may serve as the primary fundamental structural unit or precursor for the early formation of the UO_(2)(H_(2)AsO_(4))_(2)·nH_(2)O mineral phase.Altogether,this study contributes to advancing the understanding of the formation of uranyl arsenate min-erals at the molecular scale and provides a theoretical basis for predicting and regulating uranium and arsenic mobilization in their coexisting environment.
文摘The crystal structure of Di-nitratobis(ethylcaprolactam)uranyl(Ⅱ) UO_2[CH_2(CH_2)_4CONC_2H_5]_2(NO_3)_2 was established by a single-crystal X-ray diffraction study.It is triclinie, space group P1, with a=7.171(2), b=8.655(3), c=10.182(5)A, α=78.27(3), β=70.63(3), γ=81.76(3)°, V=581.7(4)A^3, Z=l, Dc=1.94 g.cm^(-3).Final R value is 0.0218.The result reveals that uranyl ion is coordinated to six oxygen atoms, two of them are from two carbonyl groups of ethylcaprolactam and the other four are from two nitrate groups.
基金supported by the National Natural Science Foundation of China(Nos.52170083,51808143)the Science and Technology Innovation Program of Hunan Province(No.2022RC1125)the Hunan Provincial Natural Science Foundation of China(No.2021JJ20007)。
文摘In this study,we present a self-driven photoelectrocatalytic(SD-PEC)system that effectively treats complex uranium-bearing wastewaters for both uranium recovery and organic matter decomposition while generating power.The system utilizes a titanium dioxide nanorod array(TNR)photoelectrode coupled with a silicon solar cell to optimize electron transport,while the cathode is composed of a carbon fiber coated with carboxylated carbon nanotubes(CCNT/CF),which efficiently reduce UO_(2)^(2+).The results demonstrate significant removal efficiency of uranium(complete removal in 25 min at a rate constant of~0.248 min^(-1)),as well as substantial degradation of organic impurities.Furthermore,the system generates sufficient power output to light an LED lamp and exhibits superior performance under various complex wastewater conditions,including simulated seawater and real uranium tailings wastewater.These findings underscore the potential of the SD-PEC system as a versatile approach for sustainable treatment and energy recovery of radioactive wastewater.The significance of this research extends to global environmental challenges,offering an innovative solution for managing radioactive wastewater while simultaneously contributing to renewable energy generation.
基金Project supported by the Science and Technology Development Foundation of China Academy of Engineering Physics （Grant No. 2011A0301003）.
文摘Uranyl （VI） amidoxime complexes are investigated using relativistic density functional theory. The equilibrium structures, bond orders, and Mulliken populations of the complexes have been systematically investigated under a generalized gradient approximation （GGA）. Comparison of （acet） uranyl amidoxime complexes （[UO2（AO）n]2-n, 1≤ n≤4） with available experimental data shows an excellent agreement. In addition, the U-O（1）, U-O（3）, C（1）-N（2）, and C（3） N（4） bond lengths of [UO2（CH3AO）4]2- are longer than experimental data by about 0.088, 0.05, 0.1, and 0.056 A. The angles of N（3） O（3）-U, O（2）-N（1）-C（1）, N（3）-C（3）-N（4）, N（4）-C（3） C（4）, and C（4）-C（3）-N（3） are different from each other, which is due to existing interaction between oxygen in uranyl and hydrogen in amino group. This interaction is found to be intra-molecular hydrogen bond. Studies on the bond orders, Mulliken charges, and Mulliken populations demonstrate that uranyl oxo group functions as hydrogen-bond acceptors and H atoms in ligands act as hydrogen-bond donors forming hydrogen bonds within the complex.
基金financially supported by the National High Technology Research and Development Program of China (No. 21677146)National Natural Science Foundation of China (Nos. 21876178, U1607102)the Anhui Provincial Natural Science Foundation (No. 1708085MB31)
文摘An acrylic modified pumpkin vine-based biochar(p-PVB-PAA) is synthesized by non-thermal plasma-grafting modification of pumpkin vine-based biochar(PVB) for the removal of uranyl from an aqueous solution. Microscopic characterization reveals that compared to PVB the surface of p-PVBPAA has more oxygen-containing functional groups by strong chemical bonding and the specific surface area is increased to 275.3 m^2 g^-1 from 3.8 m^2g^-1. It is found that p-PVB-PAA showed a much higher maximum adsorption capacity for uranyl from aqueous solutions than PVB, which were207.02 mg g^-1 and 67.58 mg g^-1 at pH=5 and 298 K, respectively. Moreover, the adsorption behavior follows a pseudo-second-order kinetics model and the Langmuir adsorption model.Additionally, macroscopic experiments and spectroscopic studies verified that the significantly improved adsorption performance of the p-PVB-PAA is due to surface complexation and electrostatic interactions. Furthermore, the very high removal efficiency and excellent regeneration ability(the percentage of the removal still remained at nearly 90% after five cycles) makes this low-cost, easily obtained, and environmentally friendly material attractive for commercial application.
基金financially supported by the National Natural Science Foundation of China to Z.Chai(91026000) to D.Wang(91226105)by the CAS Hundred Talents Program to D.Wang(Y2291810S3)
文摘The adsorption of uranyl on hydroxylated α-SiO_2(001) in the presence of a series of anionic ligands, i.e. OH^-, CO_3^(2-), NO_3^-, H_2PO_4^-, HPO_4^(2-),CH_3COO^-(Ac^-), C_6H_5COO^-(PhCO_2^-), C_6H_5O^-(PhO^-), was studied by the periodic density functional theory(DFT) implemented in the Vienna ab initio simulation package(VASP). For the ligands other than OH^-and PhO^-, only the bidentate coordination modes to the uranyl were considered. The excess charge effect of a charged system was first evaluated by constructing models with net charge as is or neutralized by creating defect at the bottom of silica, and the results show that a neutralized model, even with defects, is more realistic than the charged ones.All uranyl species prefer to bind with the deprotonated site(—O^-) rather than the protonated one(—O_H), which suggests that the increase of pH,which leads to the deprotonation of the surface, may enhance the uranyl adsorption. On the other hand, the anionic ligands, which are formed at higher pH, have negative effects. The weaker acidic ligands, such as H_2CO_3, H_3PO_4 and H_2O, whose speciation in solutions is sensitive to the fluctuation of pH, have more complex effect on the uranyl adsorption than strong acids or bases. Humic substances may coordinate with uranyl through carboxyl and phenolic groups, with the carboxyl group bound stronger. The ternary complexes with one bidentate(or monodentate)anion and one(or two) H20 as ligands, which leads to the uranyl penta-coordinated in its equatorial plane, are more favorable than other configurations when bound to the same anionic ligand. Both the charged nature and the coordination behavior of an anionic ligand are relevant to its ability to influence the adsorption of uranyl on the mineral surface. In addition, the uranyl species adsorbed at the surface functionalized by anionic ligands were also addressed, and the functionalized surfaces have weaker interaction with hydrated uranyl dication.
基金supported by National Natural Science Foundation of China(No.91226112)the specialized research fund for the Doctored Program of Higher Education of China(No.20110001120121)
文摘Black precipitates were successfully obtained by radiolytic reduction of ammonium uranyl tricarbonate in the aqueous solution of HCOONH_4 by one step.TEM,SAED,EDS,and XRD analysis indicated that the precipitates consist of hollow UO2 nanospheres（φ：30-50 nm,wall thickness：8-15 nm,and cavity diameter：10-20 nm）.The effect of HCOONH4 concentration,irradiation time and dose rate on the morphology,and size of nanospheres was investigated.Then,a gas-bubble template mechanism was proposed.
基金This work was supported by the Funds of the Key Laboratory of Organic Syntheses of Jiangsu province (No. KJS01018) and the Funds of Young Teachers of Suzhou University
文摘The new uranyl complex UO2(NO3)2[PhN(CH3)C(O)(CH3)NPh]2 was synthesized and its crystal structure has been determined by single-crystal X-ray diffraction. Crystal data: C30H32N6O10U, triclinic, space group P with a = 7.772(1), b = 9.267(1), c = 12.644(1) ? a = 68.246(8), b = 73.871(9), g = 84.99(1)o, V = 812.4(2) ?, Mr = 874.65, Z = 1, Dc = 1.788 g/cm3, F(000) = 426, m = 5.062 mm-1, the final R = 0.022 and wR = 0.059 for 3571 observed reflections (I > 2s(I)). The central uranyl ion is coordinated by six oxygen atoms, two from the carbonyl groups of N,N-dimethyl-N,N-dibenzenyl-urea molecules and the other four from two nitrate groups.
基金the support of this work by National Natural Science Foundation of China(Nos.21571171,21301168,U1407101)Jilin Province Youth Foundation(No.20130522123JH)
文摘Hydrothermal reactions of uranyl nitrate and 4,4＇-oxidiphthalic acid（H4L） resulted in the formation of three new uranyl-organic framework materials,namely（NH4）2[（UO2）3（L）2]·5H2O（1）,（NEt4）[（UO2）3（H2O）（L）（HL）]（2） and（UO2）7（H2O）2（phen）4（L）2（HL）2（3）（NEt4 = tetraethylammonium,phen = 1,10-phenanthroline）.These three structures all comprise common uranyl pentagonal bipyramids.In 1,UO7polyhedra are linked by hexadentate ligands to form a 3D framework with 1D channels,in which are located NH4^＋ ions and water molecules.While in 2,the organic ligands adopt pentadentate and hexadentate coordination modes,ligating UO7 units to create a layered structure with channels filled by NEt4^＋ ions.For 3,uranyl square bipyramids are also accommodated together with pentagonal bipyramids,which are linked by tetradentate carboxylate ligands to produce the layered assembly.Phen molecules also coordinate to the uranyl centers to build up the structure.Luminescent studies indicate that 2 and 3 exhibit the characteristic uranyl emission.
基金National Science Foundation of China(Nos.41002013,40973029,41273074 and 41222015)the Foundation for the Author of National Excellent Doctoral Dissertation of PR China(No.201228)+1 种基金Newton International Fellowship Programthe financial support from the State Key Laboratory for Mineral Deposits Research
文摘We use molecular dynamics simulation to study the mechanisms involved in the adsorption of aqueous uranyl species(UO_2^(2+)) to the basal surfaces of clay minerals,including kaolinite,pyrophyllite and montmorillonite.Uranyl ion can form various complexes with carbonates,namely,[UO_2(H_2O)_5]^(2+),[UO_2(H_2O)3(CO_3)],[UO_2(H_2O)2(CO_3)_2]^(2-),[UO_2(CO_3)_3]^(4-).The simulations show that at aqueous clay interfaces,both uranyl species and surface type control the adsorption pattern.The noncarbonato and monocarbonato uranyl species can form outer-sphere complexes on siloxane surfaces through electrostatic interaction,but the dicarbonato and tricarbonato uranyl complexes rarely adsorb on the siloxane surfaces.Strong outer-sphere adsorptions of the uranylcarbonate complexes on gibbsite surfaces are observed,which are fixed by hydrogen bonds between the ligands(carbonate and/or H_2O) and surface hydroxyls.The sorption behaviors derived in this study provide new insights into understanding the migration and enrichment of uranium and other radionuclides.
基金Supported by National Natural Science Foundation of China(Nos.11175234 and 11105210)the"Strategic Priority Research Program"of the Chinese Academy of Sciences(No.XDA02030200)+1 种基金the"Knowledge Innovation Program"of the Chinese Academy of Sciences(No.KJCX2YW-N49)Shanghai Municipal Commission for Science and Technology(Nos.11ZR1445400 and 12ZR1453300)
文摘Amino-type adsorbents(ATAs) were prepared by radiation-induced graft copolymerization of 4-hydroxybutyl acry late glycidyl ether(HB) onto a polyethylene-coated polypropylene(PE/PP) duplex fiber of a non-woven fabric,and modified with different amines of ethylenediamine(EDA),diethylenetriamine(DETA),triethylenetetramine(TETA) and diethylamine(DEA).The adsorption behavior of uranyl ions onto the ATAs was studied in batch experiments.The effects of the contact time,initial concentration of the ions,temperature,and pH value.The salinity were investigated along with the adsorption kinetics and the adsorption isotherms.The kinetic experimental data followed the pseudo second-order kinetic model,and the adsorption isotherms correlated well with the Langmuir model.The ATAs showed good efficiency in adsorbing uranyl ions,with the best saturation adsorption capacity being 64.26 mg g^(-1) for ATA-DETA within 120 min.The temperature dependence of ATADETA was quite abnormal and the quickest behavior was obtained at 25 ℃.ATAs showed good adsorption capacity over a wide pH range of 4.0-8.5,and HCl could be used in the elution process.Salinity of the solution had great effect on the adsorption capacity,3.5%salinity resulted in a 55%loss of capacity from ATA-DETA.The selectivity of ATA-DETA showed an order of:UO_2^(2+)≈Fe^(3+)> Zn^(2+) > VO_3^- > Co^(2+) > Ni^(2+).
文摘With a heptadentate compartmental Schiff-base ligand H3L (1, 3-di[o-(salicylimino) ph- enoxyl]-2-propanol), a new binuclear diuranyl complex [(UO2)2L(OH)]?DMF, C38H45N5O13U2, was synthesized and the crystal structure was determined by X-ray diffraction techniques. The coordination geometry are two pentagonal bipyramids. In each pentagon four kinds of U-O (phenoxido, hydroxo, alkoxo and ether oxo) bonds are discussed.
基金This work was supported by the Natural Science Foundation of University of Jiangsu Province(No. 03KJB150118) and the Key Laboratory of Organic Synthesis of Jiangsu Province
文摘The new uranyl complex UO2(NO3)2[C5H10NC(O)NH10C5]2 has been synthesized and its structure was determined by single-crystal X-ray diffraction. Crystal data: C22H40N6O10U, monoclinic, space group P21/c, a = 11.151(3), b = 13.907(3), c = 10.067(2) ?, β = 115.602(4)°, V = 1408.0(5) ?3, Mr = 786.63, Z = 2, Dc = 1.855 g/cm3, F(000) = 772, μ = 5.827 mm-1, R = 0.0465 and wR = 0.1065 for 2916 observed reflections (I > 2σ(I)). The central uranyl ion is coordinated by six oxygen atoms, of which two are from the carbonyl groups of di-piperidin-1-yl-methanone molecules and the other four from two nitrate groups.
基金Supported by the Project of Natural Science Foundations of Fujian (No. 2008J0172)National Natural Science Foundation of China (20705031)
文摘An organically templated 2-D uranyl sulfate, {（C2H8N）[（UO2）Cl（SO4）（H2O）] }n 1, has been hydrothermally synthesized. The crystal and molecular structures have been determined by X-ray crystallography method and spectral techniques. 1 belongs to monoclinic, space group P21/c with a = 8.3545（17）, b = 10.550（2）, c = 12.370（3）A, β = 102.64（3）°, V = 1063.9（4）A3, Mr = 464.64, De= 2.901 g/cm^3, F（000） = 836,μ = 15.710 mm^-1, Z= 4, the final R = 0.0286 and wR = 0.0685 for 10164 observed reflections with Ⅰ 〉 2σ（Ⅰ）. 1 presents a two-dimensional layer-like structure constructed from infinite anionic [（UO2）Cl（H2O）（SO4）]^- layers with [C2H8N]^＋ cations balancing the charge and a number of intermoleeular hydrogen bonds （C-H…O and O-H…Cl） existing in the solid state. The fluorescence properties of 1 have also been discussed.
文摘New solid complexes of europium, uranyl and zinc ions with N-oxides of 4-chloro-2,6-dimethylpyridine, quinoline and 4-meth- oxyquinaldinic acid in presence different anions were obtained and characterized by elemental and TG analyses, IR and luminescence spectra. The compounds are crystalline, hydrated or anhydrous salts with colours typical of metal ions. Thermal studies showed that in hydrated salts lattice or coordination water molecules are present. A role of different anions in the formation of various types of the complexes is presented.
文摘In order to discover genes capable of catalyzing the reductive immobilization of toxic chromate and uranyl ions, we have created a T7 bacteriophage library containing cDNA from environmental microbes (i.e., Geobacter sulfurreducens and Shewanella oneidensis MR-1) that are known to mediate the reduction of chromate and uranyl ions. After three rounds of screening, ten bacteriophage mutants were found to mediate the NADH-dependent reduction of chromate and uranyl ions whose cDNA encodes polypeptide chains ranging 14 to 73 amino acids in length. All identified sequences contain disordered structural motifs similar to the β-amyloid peptide (Aβ) known to promote aggregation and formation of high-affinity metal binding sites. Confirmation of this structural similarity involved phage display of the 42 amino-acid Aβ-peptides that have been found to catalyze the NADH-dependent reduction of both chromate and uranyl ions. Transmission electron microscopy (TEM) and X-ray absorption near edge structure (XANES) measurements confirm that reduced uranium is present on the surface of bacteriophage expressing the Aβ-peptide. The surface-displayed Aβ-like peptide on bacteriophage has the potential to couple naturally occurring electron transfer shuttles present in soils to promote economically viable remediation of contaminated sites containing toxic chromate and uranyl ions.
基金the National Natural Science Foundation of China(Nos.21976002,21675158,21507134,61603001,61705239 and 81773684)Natural Science Foundation of Anhui Province(Nos.1908085MB41,1908085QB75)+2 种基金Guangdong Natural Science Funds for Distinguished Young Scholars(No.2018B030306033)Pearl River S&T Nova Program of Guangzhou(No.201806010060)Pearl River Talent Program(No.2017GC010363)。
文摘Under the public spotlight,uranyl(UO22+)ions has attracted considerable attention for the extreme radioactive and chemical toxicity to ourselves and our environment.Herein,we present a simple and effective ratiometric fluorescence imaging method for the visualizing and quantitative detection UO22+ions by cellphone-based optical platform.The sensing solution was prepared by mixing label-free red carbon dots(r-CDs)and blue carbon dots(b-CDs)together with a fixed photoluminescence intensity ratio of 4:1.When UO22+ions were added,the fluorescence of r-CDs can be selectively quenched,while the fluorescence of b-CDs remains stable without spectral cha nges.With the gradually increase the amounts of UO22+ions,the different response of dual-color CDs resulted in a signification color evolution from deep red to dark purple under the ultraviolet(UV)light illumination.Then,a cellphone-based optical platform was constructed for directly imaging the color change of the samples,and the built-in Colorpicker APP quickly output the red,green and blue(RGB)channel values of these images within one second.Interesting,there was a linear relationship between the ratio of red and blue(R/B)channel values and UO22+ions concentration from 0μmol/L to 30.0μmol/L(R^2=0.92804)with the detection limit of^8.15μmol/L(signal-to-noise ratio of 3).In addition,the optical platform has also been applied to the quantification of UO22+ions in tap water and river water sample.With the advantage of low-cost,portable,easy to operation,we anticipate that this method would greatly improve the accessibility of UO22+ions detection even in resource-limited areas.
基金This work was supported by the National Natural Science Foundation of China and the funds of the Key Laboratory of Organic Syntheses of Jiansu Province
文摘The crystal structure of the title compound UO2(NO3)2[CH2(CH2)2CONC8H17] was determined by single-crystal X-ray diffraction. Crystal data: triclinic, space group P , a = 7.456(2), b = 8.371(2), c = 13.470(3) ? ?= 95.66(1), ?= 94.64(2), ?= 102.67(2), C24H46N4O10U, Mr = 788.68, V = 811.7(3) ?, Dc = 1.613 g/cm3, Z = 1, F(000) = 390, ?= 5.052 mm-1, the final R = 0.0256 and wR = 0.0568 for 2826 observed reflections (I > 2(I)). The central uranyl ions are coordinated by six oxygen atoms. Two of them are from the carbonyl groups of N-octyl-a-pyrrolidone molecules, and the other four from two nitrate groups.
