INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
·
2025
·
IF 4.6
Bin Li,Hongyu Ren,Shengda Guo,Jianbo Zhang,Zhihui Zhou,Bin Zeng,Xiangfei Guo
Tungsten powder is an essential raw material for producing tungsten carbide powders and tungsten-based alloys. However, the fabrication of high-performance spherical tungsten powders remains costly, and achieving a uniform distribution of doped elements poses significant challenges. In this study, a molecularly homogeneous W-Cr precursor solution was prepared using soluble salts, namely ammonium metatungstate ((NH 4 ) 6 [H 2 W 12 O 40 ]·xH 2 O)) and ammonium chromate ((NH 4 ) 2 CrO 4 ). Near-spherical W-Cr 2 O 3 composite powders with various Cr doping contents were synthesized through spray drying, calcination, and low-temperature hydrogen reduction. Subsequently, WC-10Co-xCr cemented carbides were fabricated via spark plasma sintering (SPS) following carburization. The effects of reduction temperature and Cr content on the morphology and phase composition of the W-Cr 2 O 3 composite powders were systematically examined. In addition, the influence of Cr doping on the mechanical properties of the cemented carbides was preliminarily evaluated. The results reveal that, at a reduction temperature of 900 °C and a Cr doping level of 0.5 wt%, the W-Cr 2 O 3 composite powders exhibit a uniform near-spherical morphology with fine and consistent particle sizes. The corresponding cemented carbide demonstrates superior overall performance. Furthermore, the Cr element is uniformly dispersed throughout the WO 3 precursor, W-Cr 2 O 3 composite powders, and the final alloy matrix.
研究领域:
材料科学
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粉末冶金
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无机化学
·
金属陶瓷
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功能材料
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2016
·
IF 2.74
Yunhong Yi,Junliang Lv,Yi Liu,Gongqing Wu
In this study, the removal of Cr(VI) from aqueous solutions by modified Litchi peel (MLP) has been investigated. Fourier-transform infrared spectrophotometer (FTIR) and scanning electron microscopic analysis (SEM) were used to characterize the biosorbents. The main results are as follow: 1) the optimal pH condition and optimum dosage for the adsorption of Cr(VI) were found to be 1–4 and 8.0 g L − 1 , respectively; 2) the adsorption process on Cr(VI) increased rapidly in 80 min and almost reached adsorption equilibrium in 100 min; 3) the adsorption of Cr(VI) increased with the increase of temperature. Furthermore, the Langmuir and Freudlich models were used to study the equilibrium process. It was found that the Langmuir model provided better correlation for the adsorption of Cr(VI) on MLP and Litchi peel (LP). The maximum adsorption at equilibrium for MLP is 9.55 mg g − 1 at 303 K, while for LP it is only 7.05 mg g − 1 at 303 K. Different kinetic models were used to analyze the kinetics of the adsorption. The pseudo-second-order model could better reflect the MLP adsorption kinetic process of Cr(VI). The thermodynamic parameters showed that the biosorption was endothermic, and there was an energy barrier for the adsorption of Cr(VI) on MLP. The present study demonstrated that MLP is an effective adsorbent for removing Cr(VI) from aqueous solutions.
研究领域:
环境科学
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生物学
✓ 已验证
DOI
高影响因子
WATER RESEARCH
·
2024
·
IF 11.4
Hongmei Tang,Meiqing Chen,Pingxiao Wu,Yihao Li,Tianming Wang,Jiayan Wu,Leiye Sun,Zhongbo Shang
Schwertmannite (Sch) is considered as an effective remover of Chromium (Cr) due to its strong affinity for toxic Cr species. Since the instability of Sch, the environmental fate of Cr deserves attention during the transformation of Sch into a more stable crystalline phase. The ubiquitous manganese(II) (Mn(II)) probably affects the transformation of Sch and thus the environmental fate of Cr. Therefore, this study investigated the impact of Mn(II) on the transformation of Cr-absorbed Sch (Cr-Sch) and the associated behavior of SO 4 2− and Cr. We revealed that the transformation products of Cr-Sch at pH 3.0 and 7.0 were goethite and Sch, respectively. The presence of Mn(II) weakened the crystallinity of the transformation products, and the trend was positively correlated with the concentration of Mn(II). However, Mn(II) changed the transformation products of Cr-Sch from hematite to goethite at pH 10.0. Mn(II) replaced Fe(III) in the mineral structures or formed Mn-O complexes with surface hydroxyl groups (-OH), thereby affecting the transformation pathways of Sch. The presence of Mn(II) enhanced the immobilization of Cr on minerals at pH 3.0 and 7.0. Sch is likely to provide an channel for electron transfer between Mn(II) and Cr(VI), which promotes the reduction of Cr(VI). Meanwhile, Mn(Ⅱ) induced more -OH production on the surface of secondary minerals, which played an important role in increasing the Cr fixation. In addition, part of the Mn(Ⅱ) was oxidized to Mn(Ⅲ)/Mn(Ⅳ) at pH 3.0 and pH 7.0. This study helps to predict the role of Mn(II) in the transformations of Cr-Sch in environments and design remediation strategies for Cr contamination.
研究领域:
环境科学
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矿物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Desalination and Water Treatment
·
2024
·
IF 1
Jianlei Gao,Zixu Zhao,Yixin Yan,Mengyuan Feng,Yu Wang,Jing Wang
ABSTRACT Hexavalent chromium [Cr(VI)] pollution has attracted intense interest in research on heavy metal pollution removal. Here, quartz sand chitosan zero-valent iron (QS-CTS@ZVI) was prepared as a permeable reactive barrier (PRB) medium material by using PRB permeable reaction wall technology and modified CTS-loaded ZVI-coated quartz sand. Characterization analyses were performed with scanning electron microscope, X-ray diffraction, Fourier-transform infrared spectroscopy and thermogravimetry-differential scanning calorimetry. The effects of the reaction time, reaction temperature, initial solution pH, initial Cr(VI) concentration, adsorbent dosage, interfering ions and adsorption cycle on the adsorption of Cr(VI) and total Cr on QS-CTS@ZVI were examined. Then, the adsorption of Cr(VI) by QS-CTS@ZVI was investigated. The results showed that for a ZVI:CTS ratio of 1:1 (m:m), a QS:ZVI ratio of 1:2 (m:m), a pH of 3, t = 5 h, an initial Cr(VI) concentration of 200 mg/L, a QS-CTS@ZVI dosage of 3.5 g/L, and T = 25°C, the efficiencies of Cr(VI) and total Cr removal by QS-CTS@ZVI were 91.6% and 90.9%, respectively. The adsorption efficiency of QS-CTS@ZVI for Cr(VI) was approximately 80% after three reuses. The coexistence of SO 4 2- in water can significantly inhibit the Cr(VI) adsorption and removal process. The process of adsorption of Cr(VI) by QS-CTS@ZVI conformed to the pseudo-second-order kinetic equation and the Langmuir adsorption isotherm model.
研究领域:
环境科学
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材料科学
✓ 已验证
DOI
高影响因子
CHEMOSPHERE
·
2022
·
IF 8.943
Yinghua Li,Yue Zhang,Fei Su,Yiyan Wang,Linlin Peng,Deze Liu
As the important carriers of environmental pollutants, microplastics have a significant impact on the migration, transformation and toxicology of heavy metals . In this paper, the adsorption behavior of Cr(VI) on PE/PS/PA microplastics under UV irradiation was studied. The research results show that the adsorption capacity of original PA is the strongest, followed by PS and PE . The specific surface area of the aged microplastics increased and new functional groups were formed, so the adsorption of three microplastics for Cr(VI) was stronger than that before aging. The average saturation adsorption of Cr(VI) by PA/PS/PE increased respectively from 730.69 μg/g, 146.11 μg/g and 75.61 μg/g to 736.31 μg/g, 318.75 μg/g and 136.78 μg/g. The Langmuir and Freundlich models showed that the adsorption is more consistent with the Freundlich model, indicating that adsorption is mainly based on multi-molecular layer adsorption on non-homogeneous surfaces. In the Cu–Cr polluted water, Cu has different effects on the adsorption behavior. Cu can promote the adsorption of Cr(VI) by PE and PS , while inhibited the adsorption by PA . In addition, environmental conditions such as temperature, pH and dissolved organic matter also have significant effects on adsorption behavior. Mechanistic analysis confirmed that electrostatic interaction plays an important role. Secondly, based on the surface physicochemical properties of the microplastics, surface complexation and van der Waals forces also significantly enhance the adsorption of Cr(VI) on the aged microplastics.
研究领域:
环境科学
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毒理学
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
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2021
·
IF 10.588
Jiawei Wen,Ying Sun,Pengge Ning,Gaojie Xu,Shanshan Sun,Zhi Sun,Hongbin Cao
The complete separation of vanadium (V) and chromium (Cr) from chrome vanadium slag is still challenging. Many studies focus on the activity of vanadium, while the effect of the other element chromium and their mutual interaction are ignored. Here, we found that proper concentration of chromium can promote the extraction efficiency of vanadium. The extraction of V and Cr with various mass ratios ranging from 8:1–4:3 at different initial pH values using primary amine N1923 were studied. The extraction efficiency of V reached nearly 100%, while none of Cr was extracted when the mass ratio of Cr and V is 0.5 under proper pH. Through the dynamic monitoring of species evolutions during extraction, the transformation of the two metals and advantage extracted species were analyzed. Cr would transfer H + for the combination of V 3 O 9 3- /V 4 O 12 4- , providing a great contribution to the continuous extraction of V. The real leachate was applied and 99.9% vanadium pentoxide was produced at a scale of 50 L/h. This paper offers deep insights of the separation of similar metal elements, and guide sustainable vanadium recovery from hazardous waste .
研究领域:
冶金学
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环境科学
✓ 已验证
DOI
PubMed
高影响因子
WORLD JOURNAL OF MICROBIOLOGY & BIOTECHNOLOGY
·
2014
·Vol. 30
·期 12
·3245-3250
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IF 1.353
Guo Xuena,Liu Wei,Bai Xuejing,He Xiuping,Zhang Borun
High-performance liquid chromatography was used to separate Cr(III) and Cr(VI) in samples with detection by inductively coupled plasma mass spectrometry(ICP-MS). The separation was achieved on a weak anion exchange column. The mobile phase was pH 7.0 ammonium nitrate solution. The redox reaction between Cr(III) and Cr(VI) was avoided during separation and determination. This separation method could be used to separate the samples with large concentration differences between Cr(III) and Cr(VI). The alkaline digestion was used to extract chromium in solid sample, which had no effect on the retention time and the peak area of the Cr(VI). However, the conversion of Cr(VI) from Cr(III) was observed during alkaline digestion, which displayed positive relation with the ratio of Cr(III) and Cr(VI) in samples. Both Cr(III) and Cr(VI) contents of chromium yeasts cultured in media with different chromium additions were determined. The spike recoveries of Cr(VI) for chromium yeasts were in the range of 95–108 %.
研究领域:
分析化学
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环境科学
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生物化学
✓ 已验证
DOI
PubMed
高影响因子
Antioxidants
·
2021
·Vol. 10
·期 7
·1089
·
IF 6.313
Farwa Basit,Min Chen,Temoor Ahmed,Muhammad Shahid,Muhammad Noman,Jiaxin Liu,Jianyu An,Abeer Hashem,Al-Bandari Fahad Al-Arjani,Abdulaziz A. Alqarawi,Mashail Fahad S. Alsayed,Elsayed Fathi Abd_Allah,Jin Hu,Yajing Guan
This research was performed to explore the vital role of seed priming with a 0.01 µM concentration of brassinosteroids (EBL) to alleviate the adverse effects of Cr (100 µM) in two different rice cultivars. Seed priming with EBL significantly enhanced the germination attributes (germination percentage, germination energy, germination index, and vigor index, etc.), photosynthetic rate as well as plant growth (shoot and root length including the fresh and dry weight) under Cr toxicity as compared to the plants primed with water. Cr toxicity induced antioxidant enzyme activities (SOD, POD, CAT, and APX) and ROS level (MDA and H2O2contents) in both rice cultivars; however, a larger increment was observed in YLY-689 (tolerant) than CY-927 (sensitive) cultivar. EBL application stimulatingly increased antioxidant enzyme activities to scavenge ROS production under Cr stress. The gene expression of SOD and POD in EBL-primed rice plants followed a similar increasing trend as observed in the case of enzymatic activities of SOD and POD compared to water-primed rice plants. Simultaneously, Cr uptake was observed to be significantly higher in the water-primed control compared to plants primed with EBL. Moreover, Cr uptake was significant in YLY-689 compared to CY-927. In ultra-structure studies, it was observed that EBL priming relieved the rice plants from sub-cellular damage. Conclusively, our research indicated that seed priming with EBL could be adopted as a promising strategy to enhance rice growth by copping the venomous effect of Cr.Keywords:antioxidants;brassinosteroids;chromium;heavy metals;rice
研究领域:
植物生理学
·
环境科学
✓ 已验证
DOI
PubMed
高影响因子
MATERIALS SCIENCE IN SEMICONDUCTOR PROCESSING
·
2025
·
IF 4.6
Yuanyuan Wang,Zhanlin Ma,Jian Wang,Jiaqi Ben,Hangmin Guan,Ping Gu,Yingfei Hu
Given the significance of the visible-light-driven reduction of heavy metal chromium (Cr(VI)), it is promising and challenging to investigate photocatalysts that exhibit strong responsiveness to visible light and possess high carrier separation efficiency. In this research, a CaIn 2 S 4 /NiTiO 3 Z-scheme heterojunction has been successfully constructed through the in-situ growth of CaIn 2 S 4 nanosheets on NiTiO 3 nanorods. The energy band alignment between CaIn 2 S 4 and NiTiO 3 in the hierarchical framework facilitated the formation of the heterojunction, which significantly enhanced visible light absorption, promoted the separation of photogenerated carriers, and maintained the high reducing capability of the CaIn 2 S 4 conduction band electrons. These synergies enabled superior Cr(VI) removal efficiency. At an optimized CaIn 2 S 4 to NiTiO 3 ratio of 1:1, about 95 % removal rate of Cr(VI) was achieved within 80 min of visible-light exposure, accompanied by a reaction rate of 0.036 min −1 that is nearly four times faster than that over CaIn 2 S 4 . Furthermore, the charge transfer driving force and reaction mechanisms were comprehensively investigated by optoelectronic measurements, emphasizing the crucial roles of electrons (e − ) in Cr(VI) reduction. This investigation showcases the potential of the CaIn 2 S 4 /NiTiO 3 Z-scheme heterojunction for photocatalytic applications in Cr(VI)-containing wastewater treatment.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Jianqi Cao,Lei Zhang,Wanlin Wang,Daoyuan Huang,Yongqi Sun
As a dominant resource for vanadium extraction, roasting of vanadium-bearing slags involves the destruction of vanadium-containing phases, mainly including iron-vanadium spinels and liquid phase, and the formation of soluble vanadate. Extraction of vanadium from iron-vanadium spinels determines the efficiency of the whole process due to their ultrastabilities. Here the phase and composition evolutions of iron-vanadium spinels containing chromium were investigated by both advanced experimental characterizations (EPMA, XRD and XPS, etc.) and thermodynamic analysis. The roles of roasting conditions were clarified, including roasting temperature, time and the presence of chromium. It was found that, upon roasting, the iron-vanadium spinels underwent a phase transition to form two distinct phases, namely a vanadium-enriched phase and a Me 2 O 3 solid solution phase. A relatively high roasting temperature with a relatively long roasting time could enhance the completeness of the roasting reaction and improve the separation of vanadium from iron and chromium. The evolution of iron-vanadium spinels with the current compositions (n(FeO): n(V 2 O 3 ): n(CaO): n(Cr 2 O 3 ) = 4: 1: 2: 0.2) followed a three-step mechanism under the current roasting conditions, i.e., an initial step of the oxidation decomposition of spinels, a reaction between CaO and V 2 O 5 to form CaV 2 O 6 , and a final reaction between residual CaO and CaV 2 O 6 to form a Ca 2 V 2 O 7 phase. Moreover, the presence of chromium resulted in an increase in the Fe 2 O 3 concentration within the vanadium-enriched phase due the formation of a solid solution with an infinite miscibility between Cr 2 O 3 and Fe 2 O 3 . The findings of this study offer not only scientific insight with regard to the evolution of iron-vanadium spinels upon roasting but also significant guidance for the optimization of roasting conditions toward target vanadium extraction from iron-vanadium spinels.
研究领域:
冶金学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2022
·
IF 7.968
Xiaoyu Lin,Xi He,Ling Lei,Yufeng Zhao,Longzhe Cui,Guiping Wu
Cr(VI)-contaminated water poses a serious threat to the environment. In this study, capsule-type biosorbent Aliquat-336-filled chitosan capsules (AFCCs) were prepared by a simple and gentle method for more efficient and eco-friendly removal of Cr(VI). The experimental results show that the uptake of Cr(VI) by AFCCs increased with increasing Aliquat-336 content. The AFCCs show excellent stability under acidic conditions, and the maximum adsorption capacity was reached at a pH of 2. The maximum adsorption capacity of AFCCs for Cr(VI) was 110.94 ± 5.07 mg/g at 20 °C, which was calculated based on the Langmuir model. The kinetic results show that the adsorption rate control process changed from liquid film diffusion to a chemical reaction with increasing shaking rate. In addition, the AFCCs and adsorption-reduction mechanism of Cr(VI) were characterized by digital photography, electron microscope , zeta potential , Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results indicated that the electrostatic attraction between quaternary amine groups in Aliquat-336 and Cr(VI) anions plays a major role in the removal of Cr(VI). Subsequently, the adsorbed Cr(VI) obtained electrons from C C/C H and NH 3 + / NH 2 + were reduced to Cr(III), while C C/C H and NH 3 + / NH 2 + were oxidized to C O, C O, =NH + , =N and N O, respectively.
研究领域:
环境科学
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材料科学
✓ 已验证
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2022
·
IF 8.025
Xiaoqi Liu,Yanyun Zhang,Yan Liu,Ting'an Zhang
In this paper, a novel grafted zeolite/Fe 3 O 4 /chitosan (ZMC-MAH-TEPA) adsorbent was greenly synthesized and evaluated for the removal of Cr(VI) and Ag(I) in single and bi-component solutions. The characterization data of XRF , XRD, FT-IR, VSM, TGA , BET and SEM showed the successful fabrication of the adsorbent with abundant -NH 2 and -NH- as well as great recovery properties (11.70 emu/g). The effects of experimental parameters, including pH value, initial concentration, temperature, time, and coexisting ions on single and bi-component adsorption, were investigated. The results demonstrated that the adsorption capacities increased with the enhanced shaking time and concentration until equilibrium was reached. The optimum pH value was 3 for Cr(VI) adsorption and 5 for Ag(I) adsorption. The maximum adsorption capacities for Cr(VI) and Ag(I) ions, obtained by the Langmuir model, were 50.75 and 70.12 mg·g −1 in single metal solutions and 45.45 and 58.94 mg·g −1 in bi-component metal solutions (Cr(VI)/Ag(I) = 1:1), respectively. Additionally, the adsorption mechanism of Cr(VI) and Ag(I) was explained in terms of electrostatic interaction and hydrogen bonding between metal ions and -NH 2 and -NH- in ZMC-MAH-TEPA. Taken together, this study provides a clean approach to synthesizing chitosan-based adsorbents for the efficient removal of Cr(VI) and Ag(I) ions.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）