HYDROMETALLURGY
·
2017
·
IF 2.605
She Chen,Zhifeng Zhang,Shengting Kuang,Yanling Li,Xiaowen Huang,Wuping Liao
A new extractant, bis(2-ethylhexyl)-1-(2-ethylhexylamino)propylphosphonate (BEAP or B) was synthesized to extract and separate zirconium and hafnium from sulfate medium. Under optimum conditions, the separation factor of Zr over Hf was found to be 6.8. The extracted complexes were determined to be ZrO(HSO 4 ) 2 ·3B and HfO(HSO 4 ) 2 ·2B. The extractions of zirconium and hafnium are both exothermic. A counter-current operation was conducted, in which the content of HfO 2 was decreased from 3% to 0.6% in the ZrO 2 product. It is suggested that much more extraction and scrubbing stages are needed to reach the goal of 0.01% HfO 2 in ZrO 2 product.
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE BRAZILIAN CHEMICAL SOCIETY
·
2023
·Vol. 34
·期 7
·1003-1012
·
IF 1.4
Wang Junlian,Liu Hui,Xu Wen,Chang Ziyong,Wang Peilong,Wang Huajun
Designing highly efficient dialkylphosphinic acid extractant for zirconium/hafnium separation relies on systematic structure-property studies. In this paper, dialkylphosphinic acids with different substituents at β-C, γ-C and δ-C for zirconium and hafnium extraction and separation from H2SO4 media were investigated. The results show that substituents at β-C, γ-C and δ-C reduce the extraction ability of dialkylphosphinic acids for both zirconium and hafnium. The substituent effect at β-C is greater than that at γ-C and δ-C. The larger steric hindrance of the substituents (ethyl > methyl > H), the weaker extraction ability of the dialkylphosphinic acids. The zirconium and hafnium separation behavior is related to the extraction ability of dialkylphosphinic acids. Dialkylphosphinic acids with stronger extraction ability show better zirconium/hafnium separation performance at higher acidity of 2.0 mol L-1 H2SO4, while those with weaker extraction ability show better zirconium and hafnium separation performance at lower acidity of 0.25 mol L-1 H2SO4. The highest hafnium/zirconium separation factor (βHf/Zr) in the current study occurs with (2-ethylhexyl)(2,4,4-trimethylpentyl)phosphinic acid (USTB-1), which reaches 19.2.
研究领域:
化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Metals
·
2025
·Vol. 15
·期 5
·468
·
IF 2.5
Shuo Tian,Jing Song,Hongqian Sun,Congcong Zhao,Zhiyu Zhang,Mingming Han,Tao Qi
Zirconium (Zr) and hafnium (Hf) are very important in nuclear and high-temperature applications, but their similar physical and chemical properties bring great challenges to separation. The current extraction methods have defects, such as low efficiency at high metal concentration. In this article, a zirconium (Zr)/hafnium (Hf) solvent extractive separation from sulfuric acid solutions using trioctylamine (TOA) as the extractant was researched at room temperature. The aqueous solution is prepared using zirconium sulfate (containing Hf), and the concentration of metal ions (Zr4+and Hf4+) was about 1.096 mol·L−1. The effects of the aqueous acidity, the concentration of TOA, the contacting time, and the organic to aqueous O/A ratio on the separation of Zr and Hf were investigated. It is observed that the Zr can be extracted in the organic phase selectively, and the optimal conditions were: TOA concentration of 40 vol%, organic to aqueous O/A ratio of 3, contacting time of 5 min. Under these conditions, the single-stage extraction rate of Zr is 61.23%, while the Hf is almost not extracted. The mechanism of Zr extraction by TOA was studied through the saturation capacity and slope methods. Based on the results, it is believed that the structure of the extracted complex may be [R3NH]2[Zr(SO4)3]. This study provides a new approach for the development of industrialized Zr-Hf separation.
研究领域:
化学工程
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核工业
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DOI
高影响因子
JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY
·
2020
·Vol. 324
·期 1
·339-348
·
IF 1.137
Zhao Jialin,Sui Ying,Peng Xiujing,Sun Guoxin,Cui Yu
Abstract Nuclear grade zirconium and hafnium are the key to promoting the development of nuclear industry. We designed and synthesized a new diphosphonic acid extractant N , N - n -octylamine di(methylene phenylphosphinic acid) (OADMPPA) with excellent extraction ability and priority for extraction of zirconium. This paper focused on the changes in extraction mechanisms and composition of complexes. With increasing concentration of HCl, cation exchange mechanism gradually changed into solvation mechanism, and complexes converted in the order of ZrOA, Zr(HA) 2 Cl 2 and ZrCl 4 ·H 2 A. Compared with bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272), OADMPPA could increase the extraction rates of zirconium and hafnium by 7.2 and 12.6 times. Graphic abstract
研究领域:
化学工程
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核工业
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2021
·
IF 5.302
Le Fu,Fuqing Jiang,Bo Li,Yongxin Cheng,Guofu Xu,Jiwu Huang,Håkan Engqvist,Wei Xia
The addition of dopant(s) is an effective strategy to regulate the microstructure and properties of ZrO 2 -based ceramics. In this study, we investigated the effects of ternary element alloying, namely tantalum (Ta), niobium (Nb), and hafnium (Hf) elements, on the microstructure and transformability of ZrO 2 nanocrystallites in a ZrO 2 -SiO 2 nanocrystalline glass-ceramic (NCGC) during sintering and thermal treatments. The ternary dopants enhanced the transformability of tetragonal ZrO 2 (t-ZrO 2 ) nanocrystallites during sintering, i.e., the dopants acted as t-ZrO 2 destabilizer. The Ta, Nb and Hf elements dissolved in ZrO 2 nanocrystallites, forming ZrO 2 solid solution. Meanwhile, lamella nanotwins were formed within many ZrO 2 nanocrystallites. No obvious segregation of dopants was detected at ZrO 2 grain boundaries. t-ZrO 2 and monoclinic (m) ZrO 2 nanocrystallites were metastable in thermal treatments process, with “t” to “m” and the reverse “m” to “t” polymorphic transformation occurred simultaneously. Meanwhile, t-ZrO 2 and m-ZrO 2 nanocrystallites had a great tendency to grow larger during thermal treatments.
研究领域:
材料科学
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陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE EUROPEAN CERAMIC SOCIETY
·
2019
·
IF 4.029
Yang Lyu,Hui Tang,Guangdong Zhao
Polymer-derived ceramics (PDCs), such as silicon oxycarbide and its derivatives, show an exceptional high oxidative stability under extreme conditions. A novel multicomponent silicon oxycarbide system tailoring with transition metal (hafnium) and boron is fabricated by sol-gel and solvothermal method. Amorphous SiHBOC was formed via the condensation of Si–OH, B–OH and Hf–OH groups, respectively, and the bonds of Si–O–Hf and Si–O–B– were detected by FTIR and XPS characterization. After high-temperature pyrolysis, the precursor is converted to a rigid ceramic material that has an 85.8 wt % ceramic yield of SiHfBOC. We investigate the oxidation resistance performance of SiHfBOC using the isothermal oxidation test at 1400 °C. The results showed that the oxidative stability of SiHfBOC was significantly superior to than those of SiBOC ceramic.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
Catalysts
·
2020
·Vol. 10
·期 4
·436
·
IF 3.52
Xiao-Chong Peng,Shan-Shan Gong,De-Yun Zeng,Shu-Wang Duo,Qi Sun
A highly efficient method for parallel synthesis of a diversity of 1,2-disubstituted benzimidazoles fromN-substituted phenylenediamines and aldehydes has been developed by using 10 mol% HfCl4on activated carbon (HfCl4/C) as the catalyst. The newly reported HfCl4/C catalyst not only mediated fast and clean formation of benzimidazoles but also could be easily removed from the reaction solution and reused up to eight times. Scanning electron microscope (SEM) and thermal desorption studies showed that activated carbon could reversibly adsorb and release Hf(IV) in ethanol upon cooling and heating, thereby serving as a thermal-controlled solid support.Keywords:benzimidazole;hafnium chloride;catalysis;activated carbon;parallel synthesis
研究领域:
有机化学
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材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A
·
2021
·Vol. 40
·期 1
·
IF 2.427
Hsain Hanan Alexandra,Lee Younghwan,Materano Monica,Mittmann Terence,Payne Alexis,Mikolajick Thomas,Schroeder Uwe,Parsons Gregory N.,Jones Jacob L.
Although 10 years have passed since the initial report of ferroelectricity in hafnia (HfO 2 ), researchers are still intensely fascinated by this material system and the promise it holds for future applications. A wide variety of deposition methods have been deployed to create ferroelectric HfO 2 thin films such as atomic layer deposition, chemical solution deposition, and physical vapor deposition methods such as sputtering and pulsed laser deposition. Process and design parameters such as deposition temperature, precursor choice, target source, vacuum level, reactive gases, substrate strain, and many others are often integral in stabilizing the polar orthorhombic phase and ferroelectricity. We examine processing parameters across four main different deposition methods and their effect on film microstructure, phase evolution, defect concentration, and resultant electrical properties. The goal of this review is to integrate the process knowledge collected over the past 10 years in the field of ferroelectric HfO 2 into a single comprehensive guide for the design of future HfO 2 -based ferroelectric materials and devices.
研究领域:
材料科学
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电子工程
✓ 已验证
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 55
·34754-34765
·
IF 3.361
Wei Qin,Kaixuan Xu,Junwei Wang,Xiaofeng Cui,Jianli Zhang,Yaqing Weng
To overcome the urgency of zirconium and hafnium separation, a novel mesoporous silica sorbent (PS-G1.0-MSNs) modified with phosphorous-functionalized G1.0 PAMAM dendrimers was prepared. The adsorption and separation behaviors of PS-G1.0-MSNs adsorbent on Zr(IV) and Hf(IV) were perfromed as a function of acidity, contact time, temperature, and ion concentrations by batch sorption methods. The maximum adsorption capacities for Zr(IV) and Hf(IV) were 25.7 mg g−1 and 5.36 mg g−1 under optimal experimental conditions, respectively, and the separation factor βHf/Zr = 2.0 > 1 demonstrated that the prepared sorbent had preferential selectivity for Hf(IV) in rich Zr(IV) solution. Moreover, kinetic data indicated that the sorption process on Zr(IV) and Hf(IV) achieved equilibrium within 120 min, and followed the pseudo-first-order model with a rate-determining step. The adsorption amount increased as temperature raised from 283 K to 303 K and the isothermal data plotted with the Langmuir model was better than the Freundlich model with monolayer behavior. Thermodynamic data analysis indicated that the sorption process was spontaneous and endothermic. Furthermore, XPS analysis revealed that the metal ion adsorption was mainly induced by the chemical coordination of Zr(IV) and Hf(IV) ions with N, O, P atoms of amide and phosphate groups. The present work provides good guidelines on the design of high efficient sorbent for the separation of Hf(IV) from Zr(IV) solutions.
研究领域:
材料科学
·
化学工程
·
环境科学
✓ 已验证
DOI
高影响因子
CORROSION SCIENCE
·
2020
·
IF 6.479
Tao Feng,Mingde Tong,Shuotian Yao,Hejun Li,Hongjiao Lin,Shifeng Wen,Peipei Wang
The B-modified SiC/HfC-SiC composites were prepared by the combination of precursor infiltration and pyrolysis (PIP) and chemical vapor deposition (CVD) methods. The microstructure, cyclic ablation and bending strength tests of the SiC/HfC-SiC composites with and without B were investigated. The results showed that the B-modified composites had a better cyclic ablation resistance than that of the composites without B. The effective residual thickness of the B-modified composites was also higher than that of the composites without B after cyclic ablation. The residual bending strength of the B-modified composites was slightly lower than that of the composites without B.
研究领域:
材料科学
·
航空航天工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
·
2024
·
IF 11.2
Xue Li,Yulei Zhang,Yanqin Fu,Junhao Zhao,Jiachen Meng
Hafnium carbonitride (HfC x N 1– x ) ceramics have drawn considerable interest due to their exceptional mechanical and thermophysical properties. Herein, we report a novel single-source precursor with Hf–N bonds as the main chain and fabricate HfC x N 1– x ceramics after pyrolysis of the precursor. The synthesis, ceramic conversion, and microstructural evolution of the single-source precursor as well as the derived HfC x N 1– x ceramics treated under various atmospheres were investigated. The results indicate that in an argon atmosphere, the nitrogen content within HfC x N 1– x decreases with rising temperature. While under a nitrogen atmosphere, the high concentration of N 2 facilitates the rapid conversion of HfO 2 to Hf 7 O 8 N 4 , which subsequently promotes the transformation of the HfC x N 1– x solid solution ceramics. During this process, there is also an inhibitory effect of N 2 on the tendency of HfN into HfC. Moreover, the desired chemical composition of HfC x N 1– x can be regulated by adjusting the N 2 concentration in the heat treatment atmosphere. The present work proposes a novel strategy for the single-source precursor-derived carbonitride ceramics and provides a deep understanding of the preparation and property modulation of HfC x N 1– x ceramics.
研究领域:
材料科学
·
陶瓷学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2024
·
IF 8.1
Jing Wang,Min Wang,Zhenjiang Lu,Jing Xie,Jianguo Huang,Jindou Hu,Yali Cao
The inefficient Ni/Fe ion utilization and poor electrical conductivity of nickel-iron layered double hydroxide (NiFe-LDH) restricts to its development in electrocatalytic oxygen evolution reaction/urea oxidation reaction (OER/UOR). Herein, self-supported Hf-doped NiFe-LDH nanosheet arrays were successfully prepared on nickel foam (Hf-NiFe-LDH/NF) via a one-step solvothermal approach for the first time, in which the introduced high-valent Hf 4+ altered the structure of electrons and chemical environment of the atoms and promoted the production of more active sites, thus realizing the fast kinetics of electron transfer on the layer. Meanwhile, the doped metal Hf ions increased the electric conduction and recycling stability of the catalyst. Astoundingly, the overpotential of Hf-NiFe-LDH/NF is barely 258 mV at a current density of 100 mA cm −2 , which is 61 mV lower than that of NiFe-LDH/NF, as well as outstanding stability for over 90 h during the OER. Similarly, the potential is only 1.37 V at 100 mA cm −2 during the UOR, 118 mV less was than at OER. Notably, Hf-NiFe-LDH/NF electrocatalyst exceeds the most previously reported electrocatalysts in terms of performance. This study highlights the benefits of Hf doping strategy in electrocatalytic OER/UOR and presents a promising new type of catalyst for future research.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）