CERAMICS INTERNATIONAL
·
2023
·
IF 5.2
Yong He,Xiao Kang,Hui-wen Xiong,Lei Zhang
Spinel composite is being considered for electrode materials in molten salt electrolysis, aiming to improve high-temperature stability and conductivity. Multi-phase composites with the general formula of (Fe 1-3 x - y Ni y Co x Cr x Mn x ) 3 O 4 ( x = 0.03, 0.06, 0.09, y = [1-2 x ]/3) were prepared via in situ SPS method. The composites were confirmed to consist of spinel and rock-salt phases through XRD and SEM analysis. Compared to the Ni–Fe–O system, the doping of Cr, Mn and Co improved the phase stability of the spinel during SPS, but hindered the shrinkage process. These composite exhibited low thermal diffusivity (1.236–2.481 m 2 /s, room temperature) and low coefficient of thermal expansion (9.8 - 14.4 × 10 −6 K −1 , 400–800 °C). Moreover, the composite with x = 0.06 and y = 0.29 exhibit 94.4 % lower permittivity, 7 times higher dielectric loss (at 40 Hz) and 26.6 % lower high-temperature conductivity (at 800 °C) than that of Ni–Fe–O system. This work demonstrates the enhanced thermal and electrical properties of spinel-based composites, which can provide inspiration to researchers and promote the development of high-temperature electrodes.
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SOLID STATE SCIENCES
·
2023
·
IF 3.5
Yinghua Lan,Xuejing Wang,Yanmei Chen,Juan Xu,Yanhui Zhang
The synergistic effect of heavy metal ions and organic pollutants can enhance the photocatalytic performance and provides a new idea for environmental governance, so it has important research value. In this work, we prepared Pd–TiO 2 composites by ascorbic acid reduction method, and obtained the crystal structure, morphology and surface state information of the composites through a series of characterizations, which verified the successful preparation of the composites. It was used for simultaneous photocatalytic removal of bisphenol A (BPA) and Cr(Ⅵ), and it was found that the photocatalytic removal efficiency was significantly improved compared to their individual removal. This can be attributed to the synergistic effect between BPA and Cr(Ⅵ), where they enhance the separation efficiency of photogenerated electron-hole pairs and prolong the lifetime of photogenerated carriers. In addition, the effects of BPA concentration and Cr(Ⅵ) concentration on photocatalytic removal efficiency were also investigated. The mechanism of photocatalytic degradation of BPA by Cr(Ⅵ) coupling system was discussed by changing the experimental conditions, it is proved that the photocatalytic products of BPA can improve the removal efficiency of Cr(Ⅵ).
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RSC Advances
·
2021
·Vol. 11
·期 50
·31795-31806
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IF 3.361
Run Fang,Bing-Chiuan Shiu,Yuansong Ye,Yuchi Zhang,Hanyu Xue,Ching-Wen Lou,Jia-Horng Lin
In this study, a novel cationic nanofiber membrane with various functional groups, good structural stability, and high adsorption capacity of Cr(VI) is presented. This nanofiber membrane is prepared by electrospinning a mixed aqueous solution of a cationic polycondensate (CP) and polyvinyl alcohol (PVA). With the aid of PVA, CP can be smoothly electrospun without using any organic solvents, and the cross-linking between CP and PVA improves the stability of membrane in acidic solution. Chemical and morphology characterization reveals that the CP/PVA membrane is composed of interwoven nanofibers that contain numerous cationic groups. Due to its high cationicity and hydrophilicity, the CP/PVA membrane shows great affinity for HCr2O7− and Cr2O72−. Adsorption experiments indicate that the CP/PVA membrane can remove Cr(VI) from simulated wastewater rapidly and efficiently in both batch and continuous mode. Besides, the presence of most coexisting ions will not interfere with the adsorption. Due to the redox reaction between the CP/PVA membrane and adsorbed Cr(VI), the CP/PVA membrane exhibits distinct color change after Cr(VI) adsorption and the discoloration is highly dependent on the adsorption amount. Therefore, in addition to serving as a highly efficient adsorbent, the CP/PVA membrane is also expected to be a convenient and low-cost method for semi-quantitative determination of Cr(VI) in wastewater.
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Journal of Environmental Chemical Engineering
·
2021
·
IF 5.909
Malcom Frimpong Dapaah,Baojian Liu,Liang Cheng
Metal-organic frameworks (MOFs) are of particular interest in the adsorption of organic pollutants . This study investigated the adsorption of aniline (ANI), furfural (FUR), and bisphenol A (BPA) in aqueous solution using MIL-101(Cr)-X (X = –H, –NO 2 , –NH 2 and, –N-2-pyc), MIL-100(Cr, Fe), HKUST-1, and ZIF-8. For the first time, an imino-functionalized MOF was used to adsorb organic compounds in water. MOFs were characterized by XRD, N 2 adsorption-desorption, SEM , TEM, elemental analysis, and FTIR. MIL-101-N-2-pyc demonstrated the highest adsorption capacity of 460.8, 126.5, and 100.7 mg/g towards 500 mg/L BPA, ANI, and FUR respectively. The adsorption isotherms better suited the Langmuir model than the Freundlich model. Importantly, 98% of BPA (100 mg/L) was removed and the kinetic data correlated well with the pseudo-second-order model (R 2 > 0.998). Binary adsorption of FUR and acetic acid (AA) were determined for industrial relevance. MIL-101-N-2-pyc outperformed commercial activated carbon and the other MIL-101s with an impressive co-adsorption of 66.1 mg/g FUR and 62.5 mg/g AA. Overall, the adsorption mechanism was due to hydrogen bonding, π-π interaction, and electrostatic attraction. Moreover, MIL-101-N-2-pyc exhibited remarkable structural stability and less than 0.01 wt% Cr leached into water. The adsorbent regeneration was improved after 4 cycles in methanol.
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Analytical Methods
·
2021
·Vol. 13
·期 32
·3561-3568
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IF 2.896
Lihong Shi,Xiaorui Dong,Guomei Zhang,Yan Zhang,Caihong Zhang,Chuan Dong,Shaomin Shuang
N-doped blue-fluorescence carbon dots (N-CDs) were fabricated via a one-pot hydrothermal method using folic acid and p-phenylenediamine. The obtained N-CDs exhibited strong fluorescence (FL) with a considerable quantum yield (QY) of 21.8% and exceptional optical stability under different conditions. Upon introducing Cr(VI), blue FL of N-CDs was distinctly quenched. On subsequent addition of L-AA, the FL of N-CDs could be partially recovered. The fluorescence changes of N-CDs have been utilized to detect Cr(VI) and L-AA in aqueous solutions with linear ranges of 0.10–150 μM and 0.75–2.25 mM, respectively, as well as limit of detection values of 9.4 nM and 25 μM, respectively. Furthermore, as-obtained N-CDs can be extended to monitor the fluctuation of intracellular Cr(VI) and L-AA. More intriguingly, N-CDs can target lysosomes with a satisfactory Pearson correction coefficient of 0.87, which indicates a promising application prospect in the biomedical field.
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ANALYTICA CHIMICA ACTA
·
2020
·
IF 5.977
Zhi Li,Jiayue Hu,Yongguang Xiao,Qingbing Zha,Lixi Zeng,Mingshan Zhu
Due to their highly porous structures, metal organic framework materials are widely used in analytic areas. In this paper, Cr-metal organic framework (MIL-101(Cr)) modified electrode was prepared and then was used as electrochemical sensor for the detection of bisphenol A (BPA). By using one kind of surfactant of cetyltrimethylammonium bromide (CTAB), the analytic performances of MIL-101 (Cr) towards BPA detection were greatly improved. Compared with pure MIL-101 (Cr), the differential pulse voltammetry (DPV) behavior of CTAB/MIL-101 (Cr) was improved 3.0 times in the presence of BPA. The hydrophobic long chain alkanes of CTAB can improve the enrichment and electrochemical oxidation for BPA. The CTAB/MIL-101 (Cr) sensor exhibited a linear range from 20 to 350 nM and a low detection limit of 9.95 nM (LOD = 3 s b / S ) and showed good reproducibility, stability and selectivity . Finally, real samples of dusts from E-waste recycling area in South China were collected and the CTAB/MIL-101 (Cr) sensor demonstrated satisfactory results for BPA detection from these dust samples.
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NANO
·
2020
·
IF 1.566
Yujiao Tu,Xuemei Chen,Yingying Xiang,Xiaotian Yuan,Kunhao Qin,Yunlin Wei,Zhiwei Xu,Qi Zhang,Xiuling Ji
Highly blue fluorescence carbon dots (CDs-MCM) were successfully prepared via a simple hydrothermal method with citric acid and ethylene diamine tetraacetic acid doped mesoporous silica MCM-41. The CDs-MCM exhibited uniform particle size and possessed good excitation-dependent characteristic. It showed highly selectivity and sensitivity in detection of Cr(VI), folic acid and good linear ranges of 0–37.5 μ M ( R 2 = 0 . 9 9 0 3 ) and 0–50 μ M ( R 2 = 0 . 9 9 4 9 ). The low detection limits were 79.31 nM and 118.73 nM for Cr(VI) and folic acid, respectively. It revealed that inner filter effect dominated in Cr(VI) quenching of the CDs-MCM fluorescent, while that of folic acid belonged to static quenching. The CDs-MCM were successfully used to detect the Cr(Vl) and folic acid in water and vegetable samples with satisfactory results. It provided new insight into environmental Cr(VI) and folic acid detection.
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CHEMOSPHERE
·
2020
·
IF 5.778
Yue Zhang,Xuyan Gao,Chunhua Xu
A non-uniform magnetic field was applied to sequester Cr(VI) with microscale zero-valent iron (ZVI). When the non-uniform magnetic field was applied, the average removal rate of Cr(VI) was increased and the lag phase was shortened with the increasing of magnetic field intensity . The instantaneous rate was fast at the beginning and about 40% of the Cr(VI) was sequestered rapidly when ZVI was added into the magnetic field system. Later, the sequestration rate of Cr(VI) was reduced and remained stable with time until Cr(VI) was removed completely. The instantaneous removal rate was positively correlated with ZVI dosage and the rate per unit mass of ZVI was 0.455 mg/(L·min·gZVI). The constant rate stage was not affected by the initial and the residual concentration of Cr(VI). In the case where no magnetic field was applied, the removal of Cr(VI) is a process in which ZVI is depassivated and its reactivity is restored continuously. The promotion of a magnetic field on the removal of Cr(VI) is mainly due to increasing the role of adsorbed reducing species of Fe 2+ or Fe 0 on the ZVI surface. Aging of ZVI under a magnetic field could enhance the release rate of Fe 2+ in the initial 5 min though the remanence of this kind of ZVI had little effect on the enhancement of the sequestration of Cr(VI).
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2020
·
IF 6.551
Xia Ruan,Hong Liu,Xiaoyong Ning,Dongye Zhao,Xianyuan Fan
Zero-valent iron (ZVI), Fe 2+ and H 2 are possible electron donors in the reduction of Cr(VI) by nanoscale ZVI (n-ZVI). However, it is often ambiguous about the roles of these electron donors in the reductive removal of Cr(VI) from groundwater and wastewater. This study investigated the action mechanisms of Fe and Ni in Cr(VI) reduction by Fe/Ni nanoparticles (n-Fe/Ni). Among the three possible reduction mechanisms of ZVI, direct electron transfer from ZVI and its corrosion product, Fe 2+ , were confirmed to be responsible for the reduction removal of Cr(VI). H 2 , another product of ZVI corrosion, was found incapable of reducing Cr(VI). In addition, the secondary metal Ni in n-Fe/Ni was found to facilitate the direct electron transfer from ZVI owing to its ability to inhibit the passivation of ZVI and to enhance the production of Fe 2+ due to the formation of Fe Ni galvanic cells . The results of characterizations on n-Fe/Ni before and after the reaction with Cr(VI) demonstrated that Cr(VI) was reduced to Cr(III), which existed as FeCr 2 O 4 precipitates on the surface of n-Fe/Ni, resulting in effective sequestration of Cr(VI). These findings are important for understanding the main mechanisms of bimetallic nanoparticles or nanomaterials for reductive immobilization of Cr(VI), and may guide further ZVI-based technology development for remediation of contaminated water or soil with redox-active contaminants.
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JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Hui Wang,Min Zhuang,Liang Shan,Jie Wu,Guixiang Quan,Liqiang Cui,Yonghao Zhang,Jinlong Yan
Nano zero-valent iron (nZVI) is an effective material for Cr(VI) treatment, however excessive agglomeration and surface oxidation limit its application. Herein, straw derived hierarchically porous carbon supported FeNi bimetallic nanoparticles (FeNi@HPC) was prepared for effective removal of Cr(VI) from water. FeNi nanoparticles were successfully loaded onto HPC with good dispersibility, and HPC caused an increase in specific surface area of FeNi nanoparticles. FeNi@HPC exhibited a significantly enhanced removal efficiency for Cr(VI) in comparison to Fe@HPC and FeNi NPs. The Ni doping content was further optimized, and the best Ni content in bimetallic NPs was estimated as 10 wt%. The conditions optimal for the activity of FeNi@HPC were assessed, and the highest removal efficiency equivalent to 30 mg L −1 of Cr(VI) was achieved at pH= 4.0 in 360 min with a dosage of 0.5 g L −1 . Higher temperatures favored the removal of Cr(VI) and FeNi@HPC manifested the lowest activation energy as compared to Fe@HPC and FeNi NPs. The action mechanisms of FeNi@HPC presumably involved electron transfer from Fe 0 , Fe 2+ and atomic hydrogen. This work not only provide a cost-effective and available HPC material to stabilize nZVI but also revealed that using FeNi@HPC is a promising approach for the remediation of water pollution .
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JOURNAL OF HAZARDOUS MATERIALS
·
2021
·
IF 10.588
Weichun Yang,Dongdong Xi,Chaofang Li,Zhihui Yang,Zhang Lin,Mengying Si
Anionic Cr(VI) and cationic heavy metals generally co-exist in industrial effluents and threaten the public health. Zero-valent iron (ZVI) particles tent to passivate rapidly, which results in a gradual drop in its reactivity. In this work, a strategy of “in-situ synthesized” iron-based bimetal was first developed to stimulate the self-activation of passivated ZVI. During this process, ZVI-loaded hydroxyapatite (ZVI/HAP) was prepared to enhance the affinity for co-existing Cu 2+ , which promoted the in-situ Cu 0 deposition on ZVI/HAP to form a Fe–Cu bimetal. The deposited Cu 0 significantly decreased the activation energy (E a ) of Cr(VI) reduction by 24.9%, and its corresponding Cr(VI) removal (96.53%) was much higher that of single Cr(VI) system (68.67%) within 9 h. More importantly, the removal of Cr(VI) and Cu 2+ were synchronously achieved. Systematical electrochemical characterizations were first introduced to explore the galvanic behaviors of iron-based bimetal. The charge transfer resistance and the negative open circuit potential of ZVI/HAP significantly decreased with the Cu 0 deposition, thereby accelerating the electron transfer from Fe 0 to Cu 2+ . The enhanced electron transfer further facilitated the Fe(II) release to promote Cr(VI) reduction. This “in-situ synthesized” iron-based bimetal strategy provides a novel pattern for ZVI activation and exhibits practical application in remediation of combined contaminant.
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CHEMOSPHERE
·
2021
·
IF 7.086
Fenglei Liu,Shan Hua,Chao Wang,Baowei Hu
Herein, using dialdehyde waste paper (DAWP) as a cross-linking agent to immobilize persimmon tannin (PT) was first used to remove the U(VI) and Cr(VI) via the “waste control by waste” concept. The microscopic and macroscopic surface properties of the as-prepared adsorbent was characterized by the advanced characterization techniques. Factors that affected the elimination process such as variable pH, coexistence ions and equilibrium time were investigated by batch techniques. The results showed that the maximal removal capacities of U(VI) and Cr(VI) on DAWP-PT were 242.3 mg/g (pH = 6.0) and 178.7 mg/g (pH = 2.0) at 298 K, which exhibited competitiveness with most of the reported solid materials. Meanwhile, adsorption data were fitted perfectly to the Langmuir and Pseudo-second-order equations, which indicated that the monolayer and homogenous chemisorption dominated the removal process. The SEM-EDX, DFT and XPS analysis conformed that adsorption of U(VI) was mainly via surface complexation, while the elimination of Cr(VI) was a redox reaction process, and about 65.33% of Cr(III) and 34.67% of Cr(VI) co-existed onto the surface of DAWP-PT. Thus, this study would provide a high-efficiency and low-cost adsorbent for radionuclide and heavy metal treatment.
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