Search query: Uranium nitride carbon

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abstract: Herein, for the first time, the authors report metal free heterojunction photocatalysts consisting of push pull conjugated polymers and polymeric carbon nitride (CN) for efficient reduction of uranium. Furthermore, the authors innovatively proposed a heteroatomic engineering strategy to further improve the visible light capture ability and separation of electron hole pairs of heterojunction photocatalysts via replacing carbon atoms in donors by nitrogen atoms. The result revealed that in the photocatalytic reduction of uranium, the kinetic constant of PFB/CN (0.037 min 1) was 2.47 times higher than that of CN (0.015 min 1) Notably, copolymerization of a nitrogen containing electron donor carbazole unit into the polymer backbone would further widen the light response range and promote electron hole separation within PCB/CN as compared to PFB/CN, leading to a higher kinetic constant (0.049 min 1) 3.27 times higher than that of CN. The current work underlines that adapting a reasonable heteroatomic engineering strategy for polymer heterojunctions is a remarkably effective strategy to develop up and coming organic semiconductor photocatalysts for efficient reduction of uranium.
author_names: Fengtao Yu

Zhenzhen Xu

Jianbo Xiong

Qiangwen Fan

Xue-feng Feng

Yuan Tao

Jianli Hua

Feng Luo
title: Heteroatom engineering of polymeric carbon nitride heterojunctions for boosting photocatalytic reduction of hexavalent uranium
year: 2020

abstract: Enrichment of UVI is an urgent project for nuclear energy development. Herein, magnetic graphitic carbon nitride nanosheets were successfully prepared by in situ anchoring of pyrrhotite (Fe7 S8 on the graphitic carbon nitride nanosheet (CNNS) which were used for capturing UVI The structural characterizations of Fe7 S8 /CNNS 1 indicated that the CNNS could prevent the aggregation of Fe7 S8 and the saturation magnetization was 4.69 emu g 1 which meant that it was easy to separate the adsorbent from the solution. Adsorption experiments were performed to investigate the sorption properties. The results disclosed that the sorption data conformed to the Langmuir isotherm model with the maximum adsorption capacity of 572.78 mg g 1 at 298 K. The results of X ray photoelectron spectroscopy (XPS) demonstrated that the main adsorption mechanism are as follows: UVI is adsorbed on the surface of Fe7 S8 /CNNS 1 through surface complexation initially, then it was reduced to insoluble UIV Thereby, this work provided an efficient and easy to handle sorbent material for extraction of UVI
author_names: Xuan Hao

Hongsen Zhang

Qi Liu

Jingyuan Liu

Rongrong Chen

Jing Yu

Milin Zhang

Peili Liu

Jun Wang
title: In Situ Anchoring of Pyrrhotite on Graphitic Carbon Nitride Nanosheet for Efficient Immobilization of Uranium.
venue: Chemistry
year: 2019

abstract: Abstract The natural crab shell with the unique structure consisting of CaCO3 was employed as the biotemplate encapsulating urea to form porous g C3N4 for U(VI) elimination. A multiscale characterization of porous g C3N4 provided evidences for successfully introducing porous structure with increased surface area as well as multi sorption sites (e.g. C N C, N (C)3 and C N H groups) The interaction of U(VI) with porous g C3N4 was investigated by batch experiments, spectroscopic analyses and theoretical calculations. The sorption experiments indicated that g C3N4 550 with the highest polymerization exhibited rapidly sequestering U(VI) within 120 min and superior uptake performance (149.70 mg/g) at pH 5.0. The presence of U N shell (R 2.80 A) calculated from EXAFS spectra revealed the U(VI) immobilization on g C3N4 550 at pH 5.0 was ascribed to the inner sphere surface complexation. The DFT calculations further evidenced the strong interaction between uranyl and g C3N4 (Ead 156.83 kcal/mol) and the most effective sorption site was inside the holes of g C3N4. The superior uranium sorption ability along with low cost and environmental friendly raw materials pointed to the high potential of porous g C3N4 for uranium preconcentration. The findings will expand an exciting direction towards the effective removal of actinides in environmental cleanup.
author_names: Chen-lu Zhang

Yang Liu

Xiaoguang Li

Hong-xia Chen

Tao Wen

Zhihao Jiang

Yuejie Ai

Yubing Sun

Tasawar Hayat

Xiangke Wang
title: Highly uranium elimination by crab shells derived porous graphitic carbon nitride: Batch, EXAFS and theoretical calculations
year: 2018

abstract: The reactivity of terminal uranium(V/VI) nitrides with CE2 (E=O, S) is presented. Well defined C=E cleavage followed by zero one and two electron redox events is observed. The uranium(V) nitride [U(TrenTIPS (N)[K(B15C5)2 (1, TrenTIPS =N(CH2 CH2 NSiiPr3 )3 B15C5=benzo 15 crown 5) reacts with CO2 to give [U(TrenTIPS (O)(NCO)[K(B15C5)2 (3) whereas the uranium(VI) nitride [U(TrenTIPS (N) (2) reacts with CO2 to give isolable [U(TrenTIPS (O)(NCO) (4) complex 4 rapidly decomposes to known [U(TrenTIPS (O) (5) with concomitant formation of N2 and CO proposed, with the latter trapped as a vanadocene adduct. In contrast, 1 reacts with CS2 to give [U(TrenTIPS (k2 CS3 [K(B15C5)2 (6) 2, and [K(B15C5)2 [NCS] (7) whereas 2 reacts with CS2 to give [U(TrenTIPS (NCS) (8) and "S" with the latter trapped as Ph3 PS. Calculated reaction profiles reveal outer sphere reactivity for uranium(V) but inner sphere mechanisms for uranium(VI) despite the wide divergence of products the initial activation of CE2 follows mechanistically related pathways, providing insight into the factors of uranium oxidation state, chalcogen, and NCE groups that govern the subsequent divergent redox reactions that include common one electron reactions and a less common two electron redox event. Caution, we suggest, is warranted when utilising CS2 as a reactivity surrogate for CO2
author_names: Peter A Cleaves

Christos E Kefalidis

Benedict M Gardner

Floriana Tuna

Eric J L McInnes

William Lewis

Laurent Maron

Stephen T Liddle
title: Terminal Uranium(V/VI) Nitride Activation of Carbon Dioxide and Carbon Disulfide: Factors Governing Diverse and Well Defined Cleavage and Redox Reactions.
venue: Chemistry
year: 2017

abstract: Abstract Thermodynamic simulation demonstrated that the accumulation of fission products in irradiation of a uranium plutonium nitride with admixture of carbon and oxygen (U 0.8 Pu 0.2 (N 0.9475 O 0.02625 C 0.02625 results in that a multicomponent oxycarbonitride solid solution is formed. This solid solution contains U, Pu,Am, Np, Zr, Y, and lanthanides as well as separate oxide (BaUO 3 SrPuO 3 carbide (URu 3 C 0.7 Mo 2 C) and nitride (U 2 N 3 phases and intermetallides U(Rh,Pd) 3 The b decay of metallic radionuclides in separate oxide and carbide phases of spent nuclear fuel changes their chemical and phase compositions, The transformation kinetics of separate phases 99 Mo 2 C 1/ 399 Tc 6 C 2/3 C, 140 BaUO 3 1/2 140 Ce 2 UO 6 1/2U was calculated.
author_names: D Yu Lyubimov

G S Bulatov

Konstantin E German
title: Comparative Analysis of the Phase Composition of Irradiated Uranium Plutonium Nitride under Joint Influence of Carbon and Oxygen Impurities and b Decomposition of Some Fission Products
venue: Radiochemistry
year: 2021

abstract: Abstract Extracting uranium from high salinity seawater at ultralow concentrations would beneficially contribute to the sustainable utilization of nuclear energy, but it poses a significant challenge. Here we report a sunlight driven photocatalysis assisted extraction (SUPER) method by utilizing a bifunctional carbon nitride material, CN550, which has shown about a tenfold improvement in both adsorption capacity and photocatalytic activity compared to g C3N4. Uranyl ions could be captured on the surface of CN550, and then deposited as metastudtite nanoparticles with light illumination. Compared with the pure physicochemical adsorption (PA) method, a tenfold higher uranium extraction capacity, up to 1556 mg g 1, has been attained. Additionally, a 25 times improvement of the partition coefficient (PC) from 0.312 to 7.778 L g 1, has also been achieved. In spiked real seawater, the extraction capacity can still achieve more than 1000 mg g 1, and the SUPER method has been found to work under natural sunlight illumination as well.
author_names: Shuang Liu

Zhe Wang

Yuexiang Lu

Hongpeng Li

Xianjie Chen

Guoyu Wei

Tong Wu

Daniel-James Maguire

Gang Ye

Jing Chen
title: Sunlight induced uranium extraction with triazine based carbon nitride as both photocatalyst and adsorbent
year: 2021

abstract: Cleavage of dihydrogen is an important step in the industrial and enzymatic transformation of N2 into ammonia. The reversible cleavage of dihydrogen was achieved under mild conditions (room temperature and 1 atmosphere of H2 by the molecular uranium nitride complex, [Cs{U(OSi(Ot Bu)3 )3 }2 (m N) 1, leading to a rare hydride imide bridged diuranium(IV) complex, [Cs{U(OSi(Ot Bu)3 )3 }2 (m H)(m NH) 2 that slowly releases H2 under vacuum. This complex is highly reactive and quickly transfers hydride to acetonitrile and carbon dioxide at room temperature, affording the ketimide and formate bridged UIV species [Cs{U(OSi(Ot Bu)3 )3 }2 (m NH)(m CH3 CHN) 3 and [Cs{U(OSi(Ot Bu)3 )3 }2 (m HCOO)(m NHCOO) 4.
author_names: Marta Falcone

Lok Nga Poon

Farzaneh Fadaei Tirani

Marinella Mazzanti
title: Reversible Dihydrogen Activation and Hydride Transfer by a Uranium Nitride Complex.
venue: Angewandte Chemie
year: 2018

abstract: Molecular nitrogen (N2) is cheap and widely available, but its unreactive nature is a challenge when attempting to functionalize it under mild conditions with other widely available substrates (such as carbon monoxide, CO) to produce value added compounds. Biological N2 fixation can do this, but the industrial Haber Bosch process for ammonia production operates under harsh conditions (450 degrees Celsius and 300 bar) even though both processes are thought to involve multimetallic catalytic sites. And although molecular complexes capable of binding and even reducing N2 under mild conditions are known, with co operativity between metal centres considered crucial for the N2 reduction step, the multimetallic species involved are usually not well defined, and further transformation of N2 binding complexes to achieve N H or N C bond formation is rare. Haber noted, before an iron based catalyst was adopted for the industrial Haber Bosch process, that uranium and uranium nitride materials are very effective heterogeneous catalysts for ammonia production from N2. However, few examples of uranium complexes binding N2 are known, and soluble uranium complexes capable of transforming N2 into ammonia or organonitrogen compounds have not yet been identified. Here we report the four electron reduction of N2 under ambient conditions by a fully characterized complex with two Uiii ions and three K+ centres held together by a nitride group and a flexible metalloligand framework. The addition of H2 and/or protons, or CO to the resulting complex results in the complete cleavage of N2 with concomitant N2 functionalization through N H or N C bond forming reactions. These observations establish that a molecular uranium complex can promote the stoichiometric transformation of N2 into NH3 or cyanate, and that a flexible, electron rich, multimetallic, nitride bridged core unit is a promising starting point for the design of molecular complexes capable of cleaving and functionalizing N2 under mild conditions.
author_names: Marta Falcone

Lucile Chatelain

Rosario Scopelliti

Ivica Zivkovic

Marinella Mazzanti
title: Nitrogen reduction and functionalization by a multimetallic uranium nitride complex
venue: Nature
year: 2017

abstract: As shown by thermodynamic modeling, accumulation of fission products in the course of irradiation of mixed uranium plutonium nitride containing 0.25 wt C impurity leads to the formation of a multicomponent carbonitride solid solution containing U, Pu, Am, Np, Zr, Y, lanthanides, and also separate carbide (UMoC2, U2RuC2, URu3C0,7, BaC2, SrC2) and nitride (U2N3) phases and intermetallic compounds U(Ru, Rh, Pd)3. The b decay of metallic radionuclides in separate carbide phases of spent nuclear fuel leads to changes in their chemical compositions. The transformation kinetics of separate dicarbide (89SrC2 89YC2, 90SrC2 90YC2 90ZrC C, 140BaC2 140LaC2 140CeC2) and complex carbide (U99MoC2 UC2 99Tc) phases was calculated.
author_names: G S Bulatov

K N Gedgovd

A G Maslennikov

D Yu Lyubimov
title: Effect of carbon impurity in irradiated mixed uranium plutonium nitride on the phase composition upon b decay of fission products
venue: Radiochemistry
year: 2017

abstract: Manganese ferrite/porous graphite carbon nitride composites (MnFe2O4/porous g C3N4[PCN] were synthesized by template assisted thermal polymerization and hydrothermal method and applied for high adsorption of U(VI) from aqueous solution. Results indicated that the maximum adsorption capacity of MnFe2O4/PCN (MPCN) was 367.9 mg g 1 under optimum conditions (pH 5, t 15 min, and T 308 K) which was higher than that of g C3N4 (185.1 mg g 1) Adsorption was well fitted with Langmuir isotherm model and pseudo second order kinetic equation. Thermodynamic analysis showed that adsorption is an endothermic, spontaneous process. X ray photoelectron spectra revealed that amino and metal oxygen groups are involved in the complexing adsorption of uranium. Adsorption efficiency remained 92.5% after five adsorption desorption cycles. The results of this paper indicated that MnFe2O4/PCN composites can be efficiently used as an ideal material for U(VI) adsorption.
author_names: Yujie Ge

Zhiqiang Alex He

Jiao Wu

Guohua Wang

Shui-bo Xie

Jinxiang Liu
title: Manganese ferrite/porous graphite carbon nitride composites for U(VI) adsorption from aqueous solutions
venue: Journal of Radioanalytical and Nuclear Chemistry
year: 2020