Minerals
·
2018
·Vol. 8
·期 4
·149
·
IF 1.835
Weiqing Wang,Jinyao Cong,Jie Deng,Xiaoqing Weng,Yiming Lin,Yang Huang,Tiefeng Peng
The effect of hydrofluoric acid (HF) pretreatment on flotation of feldspar and quartz using dodecylamine (DDA) as collector was investigated by micro-flotation, zeta potential, pyrene fluorescence spectroscopy, attenuated total reflection flourier transformed infrared spectroscopy (ATR-FTIR), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and bench scale flotation. The micro-flotation tests revealed that there was little difference in the flotation of feldspar and quartz at pH 2, using H2SO4as pH regulator. After HF pretreatment, the floatability of feldspar significantly increased while the floatability of quartz showed no change. HF pretreatment resulted in leaching of SiO2and enrichment of Na, K and Al on the feldspar surface. Consequently, the negative surface charge of feldspar increased at pH 2, which allowed for the flotation separation of the feasible minerals. This took place via an increased electrostatic adsorption between DDA and Na, K, Al on the feldspar surface, which effectively increased its hydrophobicity and as a result, improved the floatability of feldspar. An alternative process which exhibited effective separation of quartz and feldspar while recycling the tailwater from the flotation was proposed.Keywords:hydrofluoric acid;flotation;DDA;ATR-FTIR
研究领域:
矿物加工工程
·
材料科学与工程
✓ 已验证
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2019
·
IF 5.107
Yusheng Yang,Chaoqun Lan,Yingcai Wang,Zengwu Zhao,Baowei Li
In this work, a simple and sustainable approach is proposed to recover rare earths and iron from an ultrafine NdFeB waste. Rare earths are directly recovered by one-step precipitation in hydrofluoric acid and the dissolved iron by electrodeposition. The rate constant and activation energy of the reaction of rare earth hydroxide with hydrofluoric acid are investigated to understand the kinetics of iron leaching and rare earth precipitation. The rare earth precipitation is much faster than the iron leaching, enabling the rare earths separation from iron after a complete iron dissolution. The cathodic deposits of iron were characterized by X-ray photoelectron spectrometer (XPS) and scanning electron microscope (SEM). The nano-scale FeF 2 (s) and Fe(s) were deposited on Pt electrode in hydrofluoric acid solution with pH 2.3 and pH 2.89, respectively. The reduction of Fe(III) to Fe(0) was investigated by cyclic voltammetry, chronopotentiometry and open circuit chronopotentiometry. This reduction was a quasi-reversible process which was controlled by diffusion. The temperature dependence of the diffusion coefficient was established as lnD = −9.84 − 1805.43/ T and the activation energy value of the diffusion process was calculated to be −15.01 kJ mol −1 . The relationship between the Gibbs energy of intermetallic Fe-Pt formation and the temperature was established to be Δ G = −487.53 + 0.936 T . The hydrofluoric acid after the electrodeposition could be recycled for the leaching of the ultrafine NdFeB waste again.
研究领域:
材料科学
·
环境工程
·
电化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Yitong Guo,Sen Jin,Libo Wang,Qixun Xia,Aiguo Zhou
In this paper, we report a novel method to rapidly prepare two-dimensional Mo 2 CT x MXene in a low-concentration etching solution. By this method, highly pure Mo 2 CT x MXene was synthesized from Mo 2 Ga 2 C by hydrothermal etching at 180 ℃ in the solution of ammonium hydrogen fluoride (NH 4 HF 2 ). The whole process requires only 2 h and the etching solution concentration is only 1 M. Compared with the acid solutions used in other methods, NH 4 HF 2 used in this method is in solid state and its water solution is mild for handling. Compared with other methods, this method requires a lower concentration of etching solution and a much shorter etching time. The Mo 2 CT x MXene made this method have comparable microstructure and properties with those made by other methods. The initial discharge capacity as an anode of lithium-ion batteries (LIB) was 139.35 mAh g -1 at 0.1 A g -1 . After 150th cycles, the final discharge capacity was 62.42 mAh g -1 at 0.1 A g -1 . The electrochemical performance is slightly higher than the sample made by general HF etching. This is the first report to make Mo 2 CT x MXene from the etching of bifluoride salt. Due to the short etching time and low concentration of the etching solution, this method can rapidly make Mo 2 CT x MXene at in low cost, which provides a route to explore the large-scale production of Mo 2 CT x MXene.
研究领域:
材料科学
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER DEGRADATION AND STABILITY
·
2020
·
IF 4.032
Junchao Zhao,Yangyang Fu,Song Lu,Neng Tao,Zhitao Yin,Muhammad Usman Shahid,Heping Zhang
Perfluoro copolymers (PFCPs) with PFD (long chain -(CF 2 ) 7 CF 3 moiety) have a wide range of applications, such as hydrophobic and oleophobic modification of dry chemicals suppressants. However, high fluorine contents may produce much HF in thermal environments. In this study, a newly designed perfluoro copolymer (DPFCP) was synthesized and its application, pyrolysis and HF production were investigated. The pyrolysis of DPFCP could be divided into three stages, whereas the gas mainly released at the second stage, including CH 2 O, CO 2 , H 2 O, C x H y , C x H y F z , NH 3 , HF. A tube furnace was used to heating DPFCP to collect residual products and HF. The results indicated that HF was mainly produced under 370 °C.
研究领域:
材料科学
·
环境科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
ACS Nano
·
2019
·
IF 13.903
Xifan Chen,Yuanzhi Zhu,Miao Zhang,Jinyi Sui,Wenchao Peng,Yang Li,GuoLiang Zhang,Fengbao Zhang,Xiaobin Fan
MXenes, a family of two-dimensional (2D) transition-metal carbide and nitride materials, are supposed to be promising pseudocapacitive materials because of their high electronic conductivity and hydrophilic surfaces. MXenes, prepared by removing the “A” elements of their corresponding MAX phases by hydrofluoric acid (HF) or LiF–HCl etching, possess abundant terminal groups like −F, −OH, and −O groups. It has been proven that the MXenes with fewer −F terminal groups and more −O groups showed a higher pseudocapacitor performance. In organic reactions, −OH and −X (X = halogen) groups could turn to ether groups in strong nucleophilic reagent. Inspired by that, herein, we report an n-butyllithium-treated method to turn the −F and −OH terminal groups to −O groups on the Ti3C2Tx MXenes. Two types of Ti3C2Tx MXenes prepared by either HF or LiF–HCl etching were systematically investigated, and a comparison with the traditional KOH/NaOH/LiOH-treated method was also carried out. It is found that most of the −F terminal groups on the Ti3C2Tx MXenes can be successfully removed by n-butyllithium, and abundant −O terminal groups were formed. The n-butyllithium-treated Ti3C2Tx MXenes show promising applications in high-performance pseudocapacitors. A record high capacitance of 523 F g–1 at 2 mV s–1 was obtained for the n-butyllithium-treated Ti3C2Tx MXenes, and 96% capacity can remain even after 10 000 cycles.
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Science China-Technological Sciences
·
2019
·Vol. 62
·期 7
·1202-1209
·
IF 2.18
Xie XiaoJing,Zhu YuMei,Li Fang,Zhou XiaoWei,Xue Tao
During the preparation of MXenes, the control of the amounts of metal atoms and functional groups has a great influence on the properties of Surface Enhancement Raman Scattering (SERS) substrate materials. A freestanding Ti 3 C 2 T x membrane with good uniformity was prepared by HF etching of Ti 3 AlC 2 . The effect of etching time on the removal of Al atoms and the functional groups bonded to Ti 3 C 2 was precisely characterized by XRD. In addition, by using Ti 3 C 2 T x as the SERS substrate, a quadratic relationship between the enhancement intensity and concentration of the dye molecule rhodamine was achieved.
研究领域:
材料科学
·
纳米技术
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2019
·
IF 4.309
Shengkai Yang,Kelei Zhuo,Zezhong Zhang,Jianming Liu,Guangyue Bai,Jianji Wang
The low yield of graphene in the sonication-assisted aqueous-phase exfoliation is one of the challenges to its large-scale production in industry. Here, we report that hydrothermal exfoliation of graphite into graphene in NaF and polyether F127 (F127) solution can achieve a high concentration (0.55 mg mL–1) or yield (8.2%) of graphene in a low-cost, environmentally friendly manner. The defect of as-exfoliated graphene is comparable to that produced by the sonication-assisted exfoliation. In the exfoliation process, NaF and F127 are regarded as the intercalator and stabilizer. The thermal motion of H2O and F–/Na+ ion pairs, Brownian motion of graphite particles, and thermally agitation of graphite interlayers are the main driving force for exfoliating graphite. In addition, as filler of epoxy resin (EP), the graphene can enhance considerably the anticorrosion performance of EP coating. The hydrothermal exfoliation in NaF and F127 solution provides a new choice for the large-scale production of graphene.
研究领域:
材料科学
·
化学工程
✓ 已验证
DOI
高影响因子
JOURNAL OF MATERIALS RESEARCH
·
2021
·Vol. 36
·期 24
·5002-5012
·
IF 3.089
Zhou Haijun,Jiresse Nguetsa Kuate Loic,Zhang Weirun,Chen Zhengyang,Zhang Yamei,Zhang Jiaoxia
The photodegradation technology can improve the status quo of environmental problems seriously which hindered the development and progress of human society. In this work, the two-dimensional transition metal carbide Ti 3 C 2 was prepared by HF etching of Ti 3 AlC 2 , and subsequently TiO 2 crystals were produced by hydrothermal method to prepare TiO 2 /Ti 3 C 2 composite. The Ag nanoparticles were then doped by photoreduction to form a ternary Ag/TiO 2 /Ti 3 C 2 composite. The effect of photocatalytic degradation of the methyl orange solution by Ag/TiO 2 /Ti 3 C 2 was investigated. The degradation only with Ag/TiO 2 /Ti 3 C 2 is worser than TiO 2 /Ti 3 C 2 , so H 2 O 2 was added to improve the catalytic ability and explore the photocatalytic mechanism. In 420 min, the degradation efficiency of methyl orange (MO) solution reached 71.09% due to the active-free radicals preventing the recombination of electron hole pairs to improve the catalytic performance of photocatalytic materials. Graphical abstract
研究领域:
环境科学
·
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
Small
·
2021
·Vol. 17
·期 38
·2102066
·
IF 13.281
Qian Chang,Fan Wang,Zicheng Zuo,Feng He,Yao Zhao,Fuyi Wang,Yuliang Li
Suppressing the irreversible interfacial reactions is an important scientific bottleneck in the development of stable high-energy-density lithium-ion battery. The interfacial chemistry of graphdiyne (GDY) on the high-voltage cathode of LiNi 0.5 Mn 1.5 O 4 (LNMO) shows a very interesting process, in which the sp-hybridization carbon atoms chemically scavenge the hydrofluoric acid (HF) and in situ form the fluorinated GDY interface. It first turns the harmful HF into profit, and greatly enhances the interfacial stability and restrains the side reaction on the cathode under high working voltage. The GDY-coated LNMO cathode obviously alleviates the electrolyte degradation, achieves high Coulombic efficiency and reliability. Due to atomic-level selectivity and chemical trapping of HF by GDY, it effectively suppresses the dissolution of Mn, Ni elements. These results highlight the unparalleled advantages of GDY in the formation of high stable interfaces and protection of high-energy-density electrodes.
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2020
·
IF 8.758
Yuanqin Li,Kang Wang,Jiawei Chen,Wenguang Zhang,Xuehuan Luo,Zhangmin Hu,Qiankui Zhang,Lidan Xing,Weishan Li
High-voltage cathodes provide a promising solution to the energy density limitation of currently commercialized lithium-ion batteries, but they are unstable in electrolytes during the charge/discharge process. To address this issue, we propose a novel electrolyte additive, pentafluorophenyltriethoxysilane (TPS), which is rich in elemental F and contains elemental Si. The effectiveness of TPS has been demonstrated by cycling a representative high-voltage cathode, LiNi0.5Mn1.5O4 (LNMO), in 1.0 M LiPF6–diethyl carbonate/ethylene carbonate/ethyl methyl carbonate (2/3/5 in weight). LNMO presents an increased capacity retention from 28 to 85% after 400 cycles at 1 C by applying 1 wt % TPS. Further electrochemical measurements combined with spectroscopic characterization and theoretical calculations indicate that TPS can not only construct a robust protective cathode electrolyte interphase via its oxidation during initial lithium desertion but also scavenge the detrimental hydrogen fluoride (HF) present in the electrolyte via its strong combination with the species HF, F–, and H+, highly stabilizing LNMO during the charge/discharge process. These features of TPS provide a new solution to the obstacle in the practical application of high-voltage cathodes not limited to LNMO.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2025
·
IF 9
Peng Gao,Bohao He,Yu Tian,Chi Wang,Xin Sun,Ping Ning,Kai Li,Fei Wang
Hydrogen fluoride (HF) gas is a major combustion byproduct in non-ferrous metal smelting, aluminum electrolysis, coal combustion, and waste incineration processes. Due to its high corrosivity and toxicity, which pose a serious threat to human health and environmental ecosystems, it is necessary to strictly control HF emissions from industrial processes or remove it using proper methods. In this study, an oxygen vacancy-containing magnesium-based adsorbent (2NC@Mg(NO 3 ) 2 –500) was successfully synthesized via a one-pot method. This adsorbent demonstrated a maximum HF adsorption capacity of 195.65 mg·g −1 (at 90 % efficiency), significantly exceeding values reported in previous literature. The basic sites of magnesium oxide (MgO) were critical for promoting HF dissociation, while oxygen vacancies facilitated HF adsorption and its conversion to magnesium fluoride (MgF 2 ). Density functional theory (DFT) calculations further confirmed the experimental findings, demonstrating that oxygen vacancies significantly enhance HF adsorption on MgO by stabilizing fluoride ions (F - ) at the vacancy sites. The subsequent consumption of these vacancies and the conversion of MgO to MgF 2 led to adsorbent deactivation. This study highlights the important role of oxygen vacancies in HF gas adsorption.
研究领域:
环境化学
·
材料科学
·
冶金工程
·
大气污染控制
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
MATERIALS RESEARCH BULLETIN
·
2015
·
IF 2.288
Kun Ding,Dan Wang,Ping Yang,Xin Cheng
Anatase titanium dioxide (TiO 2 ) nanocaps were created via a four-step process including the preparation of SiO 2 spheres, the deposition of a TiO 2 layer to fabricate SiO 2 @TiO 2 composite spheres, the calcination for obtaining the crystal structure of anatase phase, and hydrofluoric acid (HF) etching to dissolve SiO 2 cores. The SiO 2 @TiO 2 spheres calcined at 700 °C revealed fine photocatalytic activity. Interestingly, most of samples transformed into TiO 2 nanocaps via HF etching, and TiO 2 nanocaps prepared using optimal conditions exhibited quick degradation ( k is 0.052 min −1 ) compared with commercial P25 ( k is 0.030 min −1 ) and the TiO 2 nanostructures etched by a NaOH solution. The excellent photocatalytic performance is attributed to its unique hollow hemispherical nanocaps structure, which is in favor of making full use of incident light. The photocatalysis phenomenon in visible light was also observed after depositing Au nanoparticles on anantase TiO 2 nanocaps.
研究领域:
材料科学
·
环境科学
✓ 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）