查找使用阿拉丁产品的科研文献

Electrostatic self-assembly of nanoscale FeS onto MXenes with enhanced reductive immobilization capability for U(VI) and Cr(VI)

Fenglei Liu,Shanshan Wang,Baowei Hu

Herein, a MXenes decorated nanoscale FeS composites were developed via electrostatic self-assembly strategy to achieve efficient U(VI)/Cr(VI) adsorption-reduction. Different analytical techniques were applied to adequately characterize all as-prepared materials to determine the formation of species with the desired morphology and properties. Results revealed that the special chemical structure of MXenes could improve the dispersion of FeS nano-particles and suppress its aggregation. Meanwhile, the adsorption data closely well tailored with the Langmuir isotherm and Pseudo-second-order equation, and the maximum removal efficiencies were 88.5 and 107.2 mg/g for uranium(VI) and chromium(VI). It was also found that the presence of other cations and anions had no obvious influence on removal of U(VI)/Cr(VI), whereas the elimination process was a spontaneous endothermic reaction . More importantly, according to the spectroscopic analysis and DFT calculation , both FeS and surface functional groups on Ti 3 C 2 @FeS-PDA/PEI exhibited strong chemical affinities to the targeted pollutants, while FeS could effectively reduce Uranium(VI) to Uranium(IV) and Chromium(VI) to Chromium(III). This work facilitated the omnidirectional improvement of MXenes-based materials for the de-pollution of practical radionuclide or heavy metals wastewater.

Fabrication of electrospun cellulose/ball-milled bone char membranes for fast, efficient and selective sorption of aquatic U(VI)

Junjun Li,Tatiana Cherkasova,Yakovlev Alexey Nikolaevich,Peiling Yuan

Powdered sorbents in aqueous solutions suffer from the deficiency in the solid/liquid separation even the sorption capacities were higher than their bulk or less-dispersed forms. The combination of powdered sorbents with membranes would be highly desired to balance the contradiction between high separation efficiency and sorption capability. In this study, cellulose/ball-milled bone char (CL/MB) membranes with sub-micrometer diameter (276.0–281.7 nm) and developed porosity (21.5–98.6 m 2 /g) were fabricated by electrospinning technique. Bone chars originated from the pyrolysis of bone residuals at 350 °C, 500 °C and 650 °C could well dispersed in the electrospinning solvent. CL/MB membranes could adsorb U(VI) with fast kinetics (180.0 min), efficient capacity (309.8 mg/g at pH 5.00 and T 298 K) and excellent selectivity against the interference of coexisting ions in simulated waters. With spectroscopic analysis , the formation of (Ca(UO 2 ) 2 (PO 4 ) 2 (H 2 O) 3 precipitation was dominant for the selectivity. The surface complexation of O-/reductive N-groups with U(VI), the electrostatic attraction of deprotonated O - with positively charged U(VI) species, the cation exchange of U(VI) with Ca 2+ components, and the cation-π coordination of U(VI) should also be considered. This study pave the way for the feasible utilization of electrospun CL/MB membranes as a promising sorbent to capture aquatic U(VI).

Removal Effectiveness for Washing Ce(IV), U(VI), and Zr(IV) Ions from Contaminated Purex Solvent by Hydrazine Carbonate

Guanghui Wang,Hui He,Yaorui Li,Meng Zhang,Yang Gao,Caishan Jiao

The contaminated solvent from the Purex process is washed with alkaline detergents such as sodium carbonate, which generates a large amount of secondary wastes. Therefore, hydrazine carbonate as a salt-free reagent deserves to be studied in depth. In this study, the Ce(IV), U(VI), and Zr(IV) metal ions in organic phases containing dibutyl phosphate (HDBP) of 30% tributyl phosphate (TBP)–dodecane were washed with hydrazine carbonate. The effects of the oscillation time (1 to 15 min); temperature (25°C to 85°C); cumulative number of washes (one to four times); mass fraction of hydrazine carbonate (0.1% to 20%); volume ratio of the aqueous phase to the organic phase (0.2 to 5); HDBP concentration (0 to 0.4 M); HNO3 concentration (0.05 to 8 M); and concentration of Ce(IV), U(VI), and Zr(IV) metal ions on the removal percentages of Ce(IV), U(VI), and Zr(IV) metal ions in polluted solvents were studied. The results showed that when the organic phase containing 0.02 M HDBP was washed three times with 5% hydrazine carbonate at 25°C, the removal percentages of the Ce(IV), U(VI), and Zr(IV) ions were 96%, 98%, and 94%, respectively. Meanwhile, the retention concentrations of the three in the organic phase were 35, 28, and 78 mg/L, respectively. The increase of the mass fraction of hydrazine carbonate enhances the removal of the metal ions from the organic phase into the aqueous phase. High acid is not conducive to alkaline washing of metal ions. The increase of HDBP concentration not only promotes extraction but also increases the retention capacity of the organic phase and has the most significant effect on Zr(IV). U(VI) promotes the preferential washing of Zr(IV) while Ce(IV) increases the metal retention concentration of Zr(IV) in the organic phase.

The synthesis of core-shell magnetic dendritic fibrous nano-silica for the fast and selective capture of U(VI)

Fang Wang,Tingting Li,Yun Liao,Liangshu Xia

With the rapid development of nuclear industry, a large amount of U(VI)-containing wastewater is inevitably generated and poses a serious threat to the environment. Hence, it is of great significance to remove U(VI) from aqueous solution. Herein, a novel magnetic absorbent (Fe 3 O 4 @DFNS-NH 2 ) with core–shell and fibrous structure for U(VI) capture was fabricated. The magnetic core can make the adsorbent separated conveniently from solution and the functional porous shell facilitates the fast capture of U(VI). Batch experiments were carried out to investigate the performance of the magnetic absorbent. The U(VI) adsorption onto Fe 3 O 4 @DFNS-NH 2 reached equilibrium within 60 min at pH 6 and the adsorption capacity reached 255.2 mg g −1 . The adsorption followed the pseudo-second order model and Langmuir isotherm model, indicating the nature of monolayer chemisorption. In addition, Fe 3 O 4 @DFNS-NH 2 exhibited good selectivity toward U(VI) in the presence of metal ions (K + , Cs + , Ca 2+ , Mg 2+ , Sr 2+ and Eu 3+ ). FT-IR and XPS analysis demonstrated that U(VI) was anchored onto Fe 3 O 4 @DFNS-NH 2 through the surface complexation with amino groups. These findings manifest that Fe 3 O 4 @DFNS-NH 2 shows great potential to remove U(VI) from nuclear wastewater.

Synthesis of crystalline carbon nitride with molten salt thermal treatment for efficient photocatalytic reduction and removal of U(VI)

Wu Zhiwen,Wang Bo,Zhu Yean,Xue Jinming,Nie Yidan,Xie Zongbo,Le Zhanggao

It is critical to recover uranium from wastewater containing U(VI) and to ensure the commercial development of nuclear-related energy sources. The extraction and recovery methods of uranyl ions from contaminated areas have become clearer with the rapid development of photocatalytic technology. However, there are several challenges, such as low-charge carrier migration and a lack of active sites. Crystallized carbon nitride (CCN) catalysts at different temperatures were successfully obtained to improve the efficiency of photocatalytic reduction of uranium. The characterization results show that the crystallinity of the material increased and improved the electron–hole separation efficiency. We investigated the effects of catalyst dosage, pH value of a solution, and concentration of U(VI) on the photocatalytic reactions as well as the photoreduction mechanisms. The efficiency of photocatalytic reduction of uranium is enhanced by 2.5 times with good stability in five cycles compared with bulk carbon nitride. The results demonstrate that CCN can effectively remove U(VI) by photocatalytic reduction, which has a wide range of applications prospects in the treatment of uranium-containing wastewater.

Enhanced adsorption of U(VI) and 241Am(III) from wastewater using Ca/Al layered double hydroxide@carbon nanotube composites

Haijun Chen,Zhe Chen,Guixia Zhao,Zhibin Zhang,Chao Xu,Yunhai Liu,Jing Chen,Li Zhuang,Tasawar Haya,Xiangke Wang

Ca/Al layered double hydroxide decorated carbon nanotube (Ca/Al-LDH@CNTs) composites were fabricated by co-precipitation method and hydrothermal aged treatment. The prepared Ca/Al-LDH@CNTs was characterized by SEM, TEM, EDS, XRD, FT-IR, UV–vis and XPS techniques, and applied to remove U(VI) from aqueous solutions under various environmental conditions (i.e., pH, ionic strength, temperature and contact time). The results indicated that the adsorption of U(VI) on Ca/Al-LDH@CNTs was four times higher than that of U(VI) on bare CNTs. The kinetic investigations reflected the chemisorption of U(VI) on Ca/Al-LDH@CNTs through oxygen-containing functional groups. The adsorption isotherms demonstrated that the adsorption of U(VI) was well fitted by Langmuir model and the maximum adsorption capacity of U(VI) on Ca/Al-LDH@CNTs was calculated to be 382.9 mg g −1 at 289.15 K. The thermodynamic parameters calculated from temperature-dependent isotherms suggested that U(VI) adsorption on Ca/Al-LDH@CNTs were endothermic and spontaneous process. Furthermore, Ca/Al-LDH@CNTs could remove ∼91% of 241 Am(III) at pH = 8.0, which confirmed Ca/Al-LDH@CNTs as a promising material for multiply low level radionuclides’ pollution remediation.

Constructing 3D magnetic MXenes/chitosan composites to reinforce U(VI) and Cr(VI) trapping: Excavating from performance to mechanism

Fenglei Liu,Linkai Si,Baowei Hu

Herein, we proposed a novel chitosan-induced self-assembly strategy to construct three-dimensional magnetic MXenes/chitosan composites to eliminate U(VI)/Cr(VI). Spectroscopic analysis elucidated that the magnetic composites exhibited a three-dimensional network structure, and the abundant –OH and –NH 2 groups played a pivotal role in boosting elimination performance of the composites. Batch experiment demonstrated that the synergistic effect of the amino and hydroxyl groups contributed greatly to adsorption, and the maximum adsorption capacity of U(VI) and Cr(VI) was up to 106.2 and 83.1 mg/g, respectively. Meanwhile, the kinetic studies showed that an obvious transition between diffusion control and mass transfer control, and the adsorption behavior was endothermic and spontaneous. Furthermore, a comprehensive synergistic adsorption mechanism was proposed based on the systematic spectra analysis. Namely, the target contaminant was rapidly immobilized on the 3D composites via electrostatic interaction, then the U(VI) was complexed with the amino groups, while a part of Cr(VI) was reduced to Cr(III) by the hydroxyl groups. Thus, this study not only paved the way for mitigating the increasing heavy metal/radionuclide contamination, but also promoted the application of MXexes-based materials in the field of environmental remediation.

Constructing Stable Nitrogen-Rich Core–Shell CdS@MC for Photocatalytic Reduction of U(VI) in Air without Sacrificial Agent

Jiaxin Hu,Juan Zhang,Jinming Chang,Yunwen Liao,Hejun Gao,Hongquan Fu

Photocatalytic reduction of uranium from U(VI) to U(IV) has been recognized as an effective treatment method for uranium wastewater. However, most photocatalysts have to be reduced under inert gas and sacrificial agent. Here, a class of nitrogen-rich core–shell photocatalysts (CdS@MC) with high stability was successfully prepared by modifying CdS with melamine and cyanuric chloride condensation. When the initial concentration of U(VI) was 100 mg/L and the solid–liquid ratio was 0.2 g/L, the removal of U(VI) by CdS@MC without sacrificial agent under air could reached 95%. The removal rate was still above 80% after five cycles with good stability and good removal rate of U(VI) at high salt concentration. CdS@MC not only efficiently generates electrons for photocatalytic reduction of U(VI), but also generates H2O2 from O2, which then reacts with uranyl ions to produce metastudtite. This study provides a new direction for the study of efficient uranium removal photocatalysts without sacrificial agent in air environment.

Preparation of halloysite@graphene oxide composite and its application for high-efficient decontamination of U(VI) from aqueous solution

Jiang Xiao,Shaolei Xie,Yan Jing,Ying Yao,Xingquan Wang,Yongzhong Jia

Synthesis and characterization of amidoxime modified calix[8]arene for adsorption of U(VI) in low concentration uranium solutions

Xin Lu,Shengnan He,Dongxiang Zhang,Alemtsehay Tesfay Reda,Cong Liu,Jian Feng,Zhi Yang

A novel calixarene derivative, amidoxime group modified calix[8]arene (C8A-AO), was synthesized from the nitrile group modified calix[8]arene (C8A-CN), and then the nitrile group was changed into an amidoxime group by treating with hydroxylamine under alkaline solution. The products were characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy, field-emitting scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), elemental analysis and thermogravimetric analysis (TGA). The prepared C8A-AO was applied to adsorb U(VI) in low concentration uranium solutions, less than 1 mg L−1. The effects of pH, contact time, initial concentration, and temperature on the sorption of U(VI) on C8A-AO were investigated. The adsorption efficiency of U(VI) on C8A-AO reached more than 95% in neutral solution. The results showed the adsorbent C8A-AO had an excellent distribution coefficient (Kd) when the initial uranium concentration was less than 1 mg L−1. Additionally, the adsorption results revealed that the kinetics of U(VI) adsorption followed a pseudo-second-order model and the adsorption isotherm fitted well with the Langmuir model. The results of thermodynamic parameters showed that the adsorption process of U(VI) was spontaneous, feasible and endothermic. Furthermore, the excellent selective adsorption capability of U(VI) in simulated seawater suggested that C8A-AO was a potential adsorbent for recovery of U(VI) from seawater.

Deciphering the facet-dependent scavenging potential of α-Fe2O3 nanocrystals for U(VI) and Eu(III) from aqueous phase

Xuemei Wei,Xiankui Cheng,Xinyu Zhang,Guodong Sheng,Huiting Xu

The utilization of biocompatible and inexpensive adsorbents for the effective scavenging of U(VI) and Eu(III) from wastewater is still an open challenge in nuclear waste management. Herein, three kinds of α-Fe 2 O 3 nanocrystals with different morphologies, i.e., α-Fe 2 O 3 nanospheres (HNSs), nanoplates (HNPs) and nanorods (HNRs), which were exposed (1   0   2), (0   0   1), and (1   1   0) facet, respectively, was used to scavenge U(VI) and Eu(III) from aqueous solutions via an adsorption procedure. Various techniques of N 2 adsorption–desorption, FT-IR, XRD, XPS, TEM, SEM and EDS were applied to characterize these adsorbents before or after adsorption. The results indicated that the adsorption capacity of U(VI) and Eu(III) was in the order of HNPs (0   0   1) > HNRs (1   1   0) > HNSs (1   0   2), namely, α-Fe 2 O 3 nanoplates was proved to be a good adsorbents, with removal capacity of 221 mg/g and 131 mg/g for U(VI) and Eu(III) scavenged on HNPs, respectively. The kinetics of U(VI) and Eu(III) scavenging agreed with the pseudo second order kinetic model, suggesting that chemical interaction is mainly responsible for U(VI) and Eu(III) scavenging on these materials. Furthermore, the Freundlich model fit the best for adsorption isotherms of U(VI) and Eu(III). The present study demonstrated that these α-Fe 2 O 3 nanocrystals are promising materials in nuclear waste management.

One-pot synthesis of N-doped porous carbon supported zero-valent iron nanomaterials for efficient removal of U(VI)

Maoling Pan,Jiakang Liu,Han Yang,Wanqi Zhang,Kun Huang

The rapid development of the nuclear industry has caused the accidental leakage of radioactive heavy metals, such as uranium, resulting in severe contamination of land and water sources. This paper proposes an effective and feasible program to treat uranium-contaminated wastewater. Nitrogen-doped porous carbon supported nanoscale zero-valent iron (nZVI) composites (Fe 0 @N-PCM-H 2 O 2 ) were synthesized via a combination of in situ pyrolysis and a mild H 2 O 2 post-treatment by using hyper-crosslinked porous polymer as precursor. The obtained Fe 0 @N-PCM-H 2 O 2 exhibited exceptional adsorption capability for uranyl ions (847.5 mg·g −1 ) with minimal iron leaching in aqueous solutions. Especially, H 2 O 2 post-treatment can dramatically improve the adsorption capacity and recoverable properties of the adsorbent. The successful design of this material provides a simple, efficient and environmentally friendly solution for the removal of uranium contamination, which has significant potential for future industrialization.