Journal of Central South University
·
2022
·Vol. 29
·期 6
·1811-1822
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IF 2.392
Dong Zhao-wang,Xia Yang,Guo Xue-yi,Liu Han-ning,Liu Pei-dong
Ti-6Al-4V alloy powder was prepared through a two-step reduction of a mixture of TiO 2 , V 2 O 5 and Al 2 O 3 in this study. The oxide mixture was first reduced by Mg in MgCl 2 at 750 °C in argon, where oxygen was reduced to 2.47 wt% from 40.02 wt%. The oxygen content in the final powder was eventually reduced to an extremely low level (0.055 wt%) using calcium at 900 °C in argon, and the final powder had the composition of 90.12 wt% Ti, 5.57 wt% Al, and 3.87 wt% V, which meets the standard specification of Ti-6Al-4V (ASTM F1108-09). Between the two reductions, a heat treatment step was designed to help controlling the specific surface area and particle size. The effect of the heat treatment temperature on the morphology, and composition uniformity of the powder was investigated in detail. Heat treatment above 1300 °C attributed to a dense powder with a controlled specific surface area. Thermodynamic modeling and experimental results indicated that only α -Ti enriched with Al and β-Ti enriched with V exist in the final powder, and other possible phases including Al-Mg and Al-V were excluded. This study also offers a triple-step thermochemical process for producing high-purity Ti-based alloy powder.
研究领域:
材料科学
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冶金工程
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DOI
高影响因子
JOM
·
2019
·Vol. 72
·期 4
·1687-1693
·
IF 2.305
Xia Yang,Zhao Jinlong,Dong Zhaowang,Guo Xueyi,Tian Qinghua,Zhang Siwen,Liu Yong
Ultra-high pure metallic zirconium powder was successfully obtained through a two-step gradient reduction of nano-ZrO 2 in Ar atmosphere. The first reduction by Mg was to remove ~ 85% oxygen, followed by a heat-treatment step to control the particle size and specific surface area of the powder, and the final reduction by calcium was to further purify the powder and decrease oxygen to an extremely low level (0.068 wt.%). The oxygen level in the final powder meets the standard specification of Zr sponge (ASTM B349/B349M-16). Processing parameters, including the reduction temperature, the amount of Mg and MgCl 2 and the heat treatment temperature, were investigated. Thermodynamic modeling with the assistance of HSC Chemistry software was carried out to understand the reduction reaction. This study offers a novel process for producing ultra-high pure metallic zirconium powder with the potential to replace the conventional Kroll process.
研究领域:
材料科学
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冶金学
✓ 已验证
DOI
高影响因子
Journal of Cleaner Production
·
2022
·
IF 11.072
Wenju Tao,Jiaxin Yang,Zhibo Liu,Yifan Zhang,Liyu Chen,Shaohua Wu,Jinbo Qiao,Zhengduo Xue,Zhaowen Wang
The recovery and utilization of by-product coal fly ash (CFA) in high-value-added thermal power plants is of great significance. This research focused on producing high-value-added Al–Si master alloy by aluminothermic reduction with coal fly ash as the raw material. The effects of reduction time and reducing agent amount on thermal reduction products were investigated using the single factor method. X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) results showed that Al, Si, and a small amount of Fe were the main components of the alloy. With an increase in reaction time, the mass fraction of Si in the product increased from 4.41% to 9.93%. Besides, the molten salt after thermal reduction was recovered by the electrochemical reduction process. The results showed that a longer electrolysis time is more conducive to improving the recovery of Si and Al. The results of cyclic voltammetry and electrodeposition showed that Si would be reduced in a multi-step process. Combined with thermal reduction and electrochemical secondary recovery process , the comprehensive recovery of Al and Si in fly ash could reach 87.33% and 84.02%, respectively.
研究领域:
材料科学
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环境工程
✓ 已验证
DOI
高影响因子
CHEMOSPHERE
·
2022
·
IF 8.943
Cheng Yu,Lu Yu,Abdelkader Mohamed,Jun Fang,Yichao Wu,Ke Dai,Peng Cai,Qiaoyun Huang
Light irradiation would affect the electron transfer between dissimilatory metal-reducing bacteria (DMRB) and semiconducting minerals, which may impose a great influence on the biogeochemistry cycle of heavy metals. However, the size effect of semiconducting minerals on the its electron transfer with DMRB and microbial Cr(VI) reduction under visible light irradiation is little known. Herein, the Cr(VI) reduction by Shewanella oneidensis MR-1 (MR-1) was investigated in the presence of hematite nanoparticles with average diameters of 10 nm and 50 nm in dark and under visible light irradiation. It is found that hematite nanoparticles adhered onto MR-1 cells to form the composites, leading to the decrease in surface sites and Zeta potential . Hematite mediated-Cr(VI) bioreduction rate under visible light irradiation was 0.342 h −1 , which is 3.4 folds enhancement compared with that in dark and 4.4 folds compared with the MR-1 alone under visible light irradiation. Decreasing nanoparticle size of hematite from 50 nm to 10 nm promoted the Cr(VI) reduction under visible light irradiation but impeded it in dark. It was deduced that the bioelectrons from MR-1 could promote the separation of photoelectron-hole pairs of light-irradiated hematite, which consequently enhanced the Cr(VI) bioreduction by MR-1-hematite composites. Moreover, mutant strains experiments demonstrated the vital role of c -cytochrome for the conducting network actively established by MR-1 with hematite nanoparticles. Those findings expand the understanding of the electron transfer pathway for enhancing Cr(VI) reduction by hematite-MR-1 composites, and the impact of particle size on the interaction between semiconducting mineral and electroactive bacteria under light irradiation.
研究领域:
微生物学
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环境科学
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DOI
PubMed
高影响因子
Science of Advanced Materials
·
2016
·Vol. 8
·期 5
·1066-1073
·
IF 1.812
Miao Jin-Lei,Liu Hai-Hui,Li Chuan-Bao,Zhang Xing-Xiang
Solution-processed graphene oxide (GO) films have tremendous potential in the applications of transparent electrodes. The mechanism of how the GO film is reduced by reducing gas has not been clarified because the reducing gas cannot permeate through the plane of GO. Here, an effective
chemical and thermal synergy reduction of GO film was investigated. We also revealed how the reducing gas permeates through the GO film barrier. The GO film was chemically reduced by the vapor of hydriodic acid and acetic acid (HI–AcOH, volume ratio of 1:1) at 100 °C for 3 h, followed
by annealing at 1100 °C for 0.5 h in an Ar atmosphere. The reduced graphene oxide (RGO) film had a sheet resistance of 562 Ω/〈 and a transparency of 63.7% at a typical wavelength of 550 nm, which is sufficient for many applications in optoelectronics, and this effective synergy
reduction method advances the research on graphene-based electrodes.
研究领域:
材料科学
·
纳米技术
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DOI
高影响因子
CHEMOSPHERE
·
2022
·
IF 8.943
Cheng-Feng Liang,Song-Hai Wu,Yu-Le Wang,Zhi Xu,Yong Liu,Hai-Tao Ren,Shao-Yi Jia,Xu Han
Thiosulfate (S 2 O 3 2− ) is an important ligand to complex metal cations, however, the reactivity of metal-thiosulfate complexes has barely been mentioned. In this study, the reactivity of the Cu(II)–S 2 O 3 2− system in the reduction of Cr(VI) was investigated. Kinetic results show that the reduction rates of Cr(VI) decrease with increasing pH values from 3.0 to 5.0, and 94.3% and 97.5% of 10 mg L −1 Cr(VI) was rapidly reduced within 1 min at pH 3.0 and within 30 min at pH 5.0, respectively at the molar ratio of Cu(II):S 2 O 3 2− of 0.05. We rule out the contributions of S species of tetrathionate (S 4 O 6 2− ) and sulfite (SO 3 2− ) to Cr(VI) reduction and point out that the produced Cu(I) in the Cu(II)–S 2 O 3 2− system is the key reductant that mediates the reduction of Cr(VI). We suggest that complexation between Cu(II) and S 2 O 3 2− with the formation of Cu II (S 2 O 3 ) 2 2− is the pre-requisite for the formation of Cu I (S 2 O 3 ) n 1−2n , which plays an important role in Cr(VI) reduction, accompanied by the re-oxidation of Cu(I) to Cu(II) by Cr(VI), achieving the rapid redox cycling of Cu(II)–Cu(I)–Cu(II). Such a redox cycle also mediates the denitrification process of NO 2 − to NH 3 /NH 4 + under weakly acidic conditions. This study enriches our understanding on the reducing reactivity of the Cu(II)–S 2 O 3 2− system and the importance of the Cu(II)–Cu(I)–Cu(II) redox cycle towards environmental oxidizing contaminants.
研究领域:
环境化学
·
配位化学
✓ 已验证
DOI
PubMed
高影响因子
ACS Applied Energy Materials
·
2020
·
IF 4.473
Yuanxing Wang,Cailing Niu,Yachuan Zhu,Da He,Weixin Huang
Producing syngas from electrochemical reduction of CO2 by renewable energy offers an opportunity to reduce CO2 emissions and provide chemicals and fuels. Herein, we report the careful manipulation of the reduction treatment to synthesize copper nanowire arrays (Cu NAs). By thermal oxidation, copper oxide nanowires were grown on a Cu mesh. Then, thermal reduction and electrochemical reduction were used to reduce copper oxide to Cu with the morphologic features largely preserved. The derived Cu NAs are cost-effective electrocatalysts capable of reducing CO2 and H2O for tunable syngas production. It is demonstrated that syngas, the mixture of H2 and CO, could be attained with a wide range of compositions (from 1:2 to 3:1) from CO2 reduction and H2O reduction on these Cu NAs in aqueous solutions. In addition, Cu NAs show a high current density, 4 mA/cm2, at a low potential, −0.5 V, with a high syngas faradaic efficiency of over 70%. This approach explores a new method that sheds light on tuning the syngas composition from the electrochemical CO2 reduction by Cu-based catalysts.
研究领域:
电化学
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材料科学
·
可再生能源
·
催化
✓ 已验证
产品关联
DOI
高影响因子
Nature Communications
·
2022
·Vol. 13
·期 1
·1-8
·
IF 17.694
Mu Shijia,Lu Honglei,Wu Qianbao,Li Lei,Zhao Ruijuan,Long Chang,Cui Chunhua
Cu δ+ sites on the surface of oxide-derived copper (OD-Cu) are of vital importance in electrochemical CO 2 reduction reaction (CO 2 RR). However, the underlying reason for the dynamically existing Cu δ+ species, although thermodynamically unstable under reductive CO 2 RR conditions, remains uncovered. Here, by using electron paramagnetic resonance, we identify the highly oxidative hydroxyl radicals (OH • ) formed at room temperature in HCO 3 - solutions. In combination with in situ Raman spectroscopy, secondary ion mass spectrometry, and isotope-labelling, we demonstrate a dynamic reduction/reoxidation behavior at the surface of OD-Cu and reveal that the fast oxygen exchange between HCO 3 - and H 2 O provides oxygen sources for the formation of OH • radicals. In addition, their continuous generations can cause spontaneous oxidation of Cu electrodes and produce surface CuO x species. Significantly, this work suggests that there is a “seesaw-effect” between the cathodic reduction and the OH • -induced reoxidation, determining the chemical state and content of Cu δ+ species in CO 2 RR. This insight is supposed to thrust an understanding of the crucial role of electrolytes in CO 2 RR.
研究领域:
材料科学
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电化学
·
表面科学
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产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2020
·
IF 16.683
Xiao-Cheng Liu,Chuan-Shu He,Zi-Yang Shen,Wen-Qiang Li,Ning Chen,Jun-Sheng Song,Xiao-Guo Zhou,Yang Mu
Fe(III) chelate reduction is of great importance in the homogeneous neutral electro-Fenton (EF) process, but its reduction mechanisms with different reductive species remain unclear. In this study, the reduction mechanisms of several typical Fe(III) chelates through electron and atomic H* were investigated using experiments and density functional theory calculations. The results indicated that the electron reduction efficiencies for [Fe(III)-EDTA] − and [Fe(III)-EDDS] − chelates were 16.23 and 8.31 times higher compared to [Fe(H 2 O) 6 ] 3+ , which was featured by low E LUMO - HOMO and concentrated LUMO distribution around Fe atom. In contrast, the atomic H* reduction efficiency for [Fe(III)-HA] 3+ chelate was 10 times higher than that of electron, attributed to high chelation ability of HA and negative energy barrier of [Fe(III)-HA] 3+ reduction in the atomic H*-dominated system. Additionally, phthalocyanine (Pc) had insignificant effect on pollutant degradation efficiency in the neutral EF systems due to the lower chelate ability of Pc with Fe(III) compared to H 2 O.
研究领域:
环境科学
·
化学
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产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2024
·Vol. 31
·期 23
·34607-34621
·
IF 0
He Haixia,Cheng Yanhui,Qiu Siwei,Sun Lei,Jin Bohua,Yuan Xiangjuan
A series of ZnO decorated reduced graphene oxide (rGO) (ZnrGO x ) with different doping ratios were synthesized by the alkaline hydrothermal method using graphene oxide (GO) and Zn(NO 3 ) 2 ·6H 2 O as precursors, and subsequently used for the adsorption study of Cr(VI) in water. The morphology, crystalline phase structure, and surface elemental properties of ZnrGO x composites were revealed by XRD, SEM, BET, FT-IR, and XPS characterizations. The results showed that ZnO nanoparticles can be clearly seen on the surface of layered rGO. Meanwhile, as the doping rate increased, the C = C double bonds were broken and more carboxylic acid groups formed in ZnrGO x . In addition, the ZnrGO 0.1 composite had the most excellent adsorption performance and good stability, and reusability. The adsorption removal rate of Cr(VI) can reach 99%, and the maximum adsorption amount of Cr(VI) was 68.9655 mg/g in 3 h. The isothermal and kinetic model simulations showed that Cr(VI) adsorption on ZnrGO 0.1 composite is a chemical adsorption process, spontaneous and endothermic. Based on the concentrations of different valence states of Cr in the solid and liquid phases, 40% of Cr(VI) was reduced to Cr(III) on the surface of ZnrGO 0.1 composite. Moreover, the adsorption-reduction mechanisms of Cr(VI) on ZnrGO 0.1 composite were further elucidated. The ZnrGO 0.1 composite manifested great potential as an efficient adsorbent for Cr(VI) removal. Graphical Abstract
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
Journal of Geophysical Research-Biogeosciences
·
2025
·Vol. 130
·期 3
·e2024JG008675
·
IF 3.5
Zhengqi Su,Huaming Guo,Zhipeng Gao,Tiantian Ke,Xiaojun Feng,Lingzhi Zhang
Although the reduction of pentavalent arsenic (As(V)) bound to Fe(III) (hydr)oxides (As(V)-containing FeOOH) coupled with organic matter (OM) degradation has received extensive attention, little is known about in situ reduction of FeOOH mineral-bound As(V) (As(V) (s) ) via electron shuttling in the presence of As(V)-reducing bacteria (AsRB). Here, anthraquinone-2,6-disulfonate (AQDS), Suwannee River humic acid (SRHA), and fulvic acid (SRFA) were used to establish an agar electron shuttle system with ferrihydrite-As(V)/goethite-As(V) and AsRB, which was isolated from high-As groundwater as the candidate strain (RA-1). We found that AQDS was more efficient in shuttling electrons to reduce As(V) (s) and Fe(III) than SRHA and SRFA. High contents of quinone moieties in AQDS indicated that quinone moieties were conducive to As(V) (s) and Fe(III) reduction. The reduction kinetic rates ( K red ) of As(V) (s) were higher than those of Fe(III), indicating the occurrence of in situ As(V) (s) reduction via electron shuttling. Furthermore, K red of As(V) (s) for ferrihydrite-As(V) systems was greater than that of goethite-As(V) systems, demonstrating that As(V) bound to ferrihydrite via monodentate was more easily reduced than that bound to goethite via bidentate. The relative expression levels of As metabolic genes ( ars C, arr A, and ars B) initially increased and then decreased in the late stage of experiments. High As concentrations in suspension inhibited the transcriptional activity of As metabolic genes in the late stage, reducing the electron production efficiency of RA-1 and subsequently slowing in situ reduction of As(V) (s) . This study highlights the importance of OM electron shuttling in the reduction of As(V) (s) , offering new perspectives in As enrichment in groundwater. Plain Language Summary OM can promote microbial As(V) reduction in high As groundwater systems. As a result, we explored how FeOOH mineral-bound As(V) could be in situ reduced via electron shuttling between AsRB and different OM. Our findings showed that AQDS was more effective than other two natural organic matter (NOM, i.e., SRHA and SRFA) in reducing both As(V) (s) and Fe(III), due to its high content of quinone moieties. The results of kinetic analysis demonstrated in situ reduction of As(V) (s) , and As(V) bound to ferrihydrite was more readily reduced than As(V) bound to goethite. In addition, the transcriptional activities of three As metabolic genes initially increased but later declined due to high As concentrations, which further slowed the As(V) (s) reduction process. Overall, these findings provide new insights into organic-mediated As cycling in contaminated groundwater. Key Points High quinone contents in AQDS led to a higher reduction extent of As(V) (s) than in SRHA and SRFA The values of K red, As were greater than those of K red, Fe , demonstrating in situ reduction of As(V) (s) Changes in As metabolic genes affected the electron production efficiency of RA-1 and As(V) (s) reduction
研究领域:
环境科学
·
微生物学
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产品关联
DOI
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2021
·
IF 7.312
Ousmanou Njoya,Shengxin Zhao,Xingyu Kong,Jimin Shen,Jing Kang,Binyuan Wang,Zhonglin Chen
The treatment of industrial wastewater containing Cr(VI)–organic compounds is a long-term concern in the field of environment. In order to realize the high-efficient reduction of Cr(VI) and solve the problem of Cr(III) residue in water environment, a novel catalytic chemical reduction/membrane filtration method was developed for the removal of total Cr (TCr) in a system with coexisting Cr(VI) and oxalate (Ox). The effects of the concentrations of Ox, Fe(III), and Al(III), the dosage of NaBH 4 , and sedimentation time on the removal of Cr(VI) containing Ox by NaBH 4 were investigated. Additionally, the simultaneous removal of turbidity and TCr using a microfiltration membrane was investigated, and the reason for the enhanced TCr removal was clarified. The results of ion chromatography (IC), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) suggested that when Cr(VI) and Ox coexist, low concentrations (0.3 mM) of Fe(III) or Al(III) contributed significantly to the high turbidity caused by the formation of suspended solids (SS) following the reduction of Cr(VI) by NaBH 4 . However, almost all the Cr(III) could be removed by a 1-μm microfiltration membrane. The high turbidity system formed by Ox and Cr(III) is unstable, and some Ox will gradually release their binding sites with Cr(III) with the extension of the natural settling time. For 24 h, 53.75% of Ox was involved in the formation of SS, while in the presence of Fe(III) or Al(III), only 11.28% and 6.30% of Ox were involved, respectively. High concentrations of Fe(III) and Al(III) enhanced the reduction of Cr(VI) by NaBH 4 . The removal of TCr was close to 100% after natural sedimentation for 15 min and combined with a microfiltration membrane. This result is caused because Fe(III)–Cr(III) or Al(III)–Cr(III) can form larger SS, which is easily intercepted by the microfiltration membrane. The development of a novel combined method of catalytic chemical reduction and membrane filtration will be beneficial for reducing the retention of TCr in the environment.
研究领域:
环境科学
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化学工程
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）