SCIENCE OF THE TOTAL ENVIRONMENT
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2019
·
IF 5.589
Zhiyong Zhou,Xueting Liu,Minghui Zhang,Jian Jiao,Hewei Zhang,Jian Du,Bing Zhang,Zhongqi Ren
Fe 3 O 4 magnetic nanoparticles were prepared by hydrothermal synthesis and their surface was modified by the sol-gel method. Polymers imprinted with magnetic Cr (VI) were prepared by using Cr 2 O 7 2− as template ion, 4-vinyl pyridine (4-VP) as monomer , isopropanol as solvent and Fe 3 O 4 as matrix. The effects of solvent type, amount of Cr (VI) addition and volume of crosslinking agent on the adsorption properties of the imprinted polymers were investigated. The polymers were characterized by Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). The adsorption equilibrium was reached within 50 min, and the maximum adsorption capacity was 201.55 mg·g −1 . The adsorption process conformed to the Langmuir model, and the results of kinetic fitting showed that the pseudo-first-order kinetic model applied. In the Cr 2 O 7 2− /AlF 4 − and Cr 2 O 7 2− /CrO 4 2− competitive systems, the imprinted polymer showed good selectivity to the template ions, with relative selectivity factors of 6.91 and 5.99, respectively. When the imprinted polymer was reused 6 times, the adsorption capacity decreased by only 8.2%, demonstrating good reusability.
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高影响因子
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
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2019
·Vol. 411
·期 27
·7165-7175
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IF 3.286
Zhang Meng Yuan,Huang Ren Feng,Ma Xiao Guo,Guo Li Hui,Wang Ying,Fan Yin Ming
A new fluorescence sensor (QDs-IIP), based on ion-imprinted polymers (IIP) as recognition element and Mn-doped ZnS quantum dots (QDs) as fluorophore, was synthesized for the selective and sensitive determination of hexavalent chromium (Cr(VI)) ions. The QD was first coated by SiO 2 layer, and then modified with Cr(VI)-imprinted polymer. Several parameters affecting fluorescence intensity such as tetraethylorthosilicate (TEOS) volume, ZnS:Mn@SiO 2 amount, and radiation time were investigated and optimized. The QDs-IIP was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), transmission electron microscope (TEM), and scanning electron microscope (SEM). Furthermore, the fluorescence quenching mechanism was investigated by using UV-VIS and fluorescence spectrophotometer, and it was found that internal filtration effect was the main fluorescence quenching mechanism. The relative fluorescence intensity (F 0 /F) increased linearly with the increase of Cr(VI) concentration in the range of 20 μg L −1 –1.0 mg L −1 . The QDs-IIP sensor showed high recognition selectivity for Cr(VI) in comparison with the QDs-NIP sensor with an imprinting factor (IF) of 2.53, and it could be reused 5 times. In addition, an analytical method of Cr(VI) based on the QDs-IIP sensor was established with a limit of detection of 5.48 μg L −1 , and was then applied to actual water samples with satisfactory results. Therefore, QDs-IIP can be deemed as a practicable fluorescent sensor for trace Cr(VI) detection.
Graphical abstract
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
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2019
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IF 4.784
Shan-Shan Li,Xue-Lian Wang,Qing-Da An,Zuo-Yi Xiao,Shang-Ru Zhai,Li Cui,Zhong-Cheng Li
Considering that the hazardous heavy metal ions like Cd(II) and Cr(VI) are widely present in the environment, nowadays employing easy-to-handle adsorption-oriented processes are feasible choices towards efficient remediation of Cd(II) and Cr(VI) from aqueous systems. Herein we developed a novel amino-functionalized bead with cost-effectiveness, high sorption capacity and fast sorption kinetics to remove Cd(II) and Cr(VI) from aqueous solution. The carboxyl methylcellulose and chitosan-derived nanostructured sorbents synthesis were mainly through chitosan and dopamine self-polymerization, doped in sodium carboxymethyl cellulose, and glutaraldehyde cross-linking. The pH value, initial concentration and contact time were investigated. Experimental data were commendably described by Freundlich isotherm and Pseudo-second-order model. The maximum adsorption capacities of Cd(II) and Cr(VI) obtained from the experimental data were 470.0 mg/g and 347.0 mg/g, respectively. The adsorbents were collaboratively characterized by FT-IR, SEM, TGA , XPS , etc., and the adsorbent basically exhibited high complexation ability to Cd(II) and showed strong electrostatic effect with Cr(VI) under acidic conditions. The recycling characteristics suggested that it possesses an outstanding recyclability. The adsorbent may have a potential as high-value biological adsorbent to remove heavy metals and it deserves further research into the practical application.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
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IF 4.175
Jingjing Xu,Chen Liu,Junfeng Niu,Yanlin Zhu,Biying Zang,Mengjuan Xie,Mindong Chen
LaFeO 3 /Bi 3 NbO 7 p-n heterojunction photocatalysts were prepared successfully through an in-situ growth method. The phase structure, optical property , morphology and microstructures of the obtained samples were studied by X-Ray diffractometer (XRD), Ultraviolet–visible absorption spectrum (UV–vis DRS), photoluminescence (PL) spectroscopy, transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM) and scanning electron microscope (SEM). The visible light responsive photocatalytic activity of as-obtained samples were investigated by the photo-reduction of Cr (Ⅵ). The effects of preparation conditions (proportion of BNO/LFO and temperature) on the activity were studied. Results showed that the as-obtained BNO-LFO-200-5 composite behaved the best photocatalytic activity (with rate constant of 0.0212 min −1 ) among all the obtained samples. The rate constant was about 42.4-times and 17.7-times as that of pristine BNO (0.0005 min −1 ) and LFO (0.0012 min −1 ), respectively. The enhanced photocatalytic property of the as-prepare LaFeO 3 /Bi 3 NbO 7 composites can be ascribed to the formation of p-n junction between BNO and LFO, which significantly increased the separation efficiency of photo-excited electron-holes.
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Environmental Science-Nano
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2019
·Vol. 7
·期 1
·286-303
·
IF 7.704
Changlin Yu,Debin Zeng,Qizhe Fan,Kai Yang,Julan Zeng,Longfong Wei,Junhui Yi,Hongbing Ji
A powerful photocatalyst is the key for photocatalytic environmental purification via sunlight harvesting and utilization. In this work, novel boron doped Sn3O4 microspheres constructed from nanoplates were designed and fabricated. Density functional theory (DFT) studies were carried out to investigate the boron doping mechanism, in which DFT predicted that boron doping would enhance the light harvesting capability and the photo-response of Sn3O4, which was proved by diffuse reflectance spectra (DRS) and transient photocurrent responses. Attributed to its unique porous structure, and enhanced light harvesting and high carrier utilization capabilities, the boron doped Sn3O4 microsphere exhibited high efficiency for Cr(IV) removal and azo dyestuff degradation. Moreover, an unexpected synergistic effect upon simultaneous removal of phenols (phenol, bisphenol A and p-chlorophenol) and Cr(VI) was observed.
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JOURNAL OF HAZARDOUS MATERIALS
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2019
·
IF 7.65
Lelin He,Deshun Huang,Zexiang He,Xiaojiao Yang,Guozong Yue,Jing Zhu,Didier Astruc,Pengxiang Zhao
MXenes, as new members of the 2D materials group, are regarded as good candidates for heavy metal removal particularly for radioactive metal element because of their high irradiation stability. However, the small interlayer distance and lack of active sites on the surface limit their further application. In this report, nanoscale zero-valent iron has been introduced into the inter-layer structure of alkaline intercalated Ti 3 C 2 (Alk-Ti 3 C 2 ) and investigated to Cr(VI) removal. The XPS spectra, SEM images, TEM images, and N 2 adsorption-desorption isotherms characterizations revealed that the OH groups on the Alk-Ti 3 C 2 surface assisted the introducing of nZVI into the inter-layer of Alk-Ti 3 C 2 and subsequently stabilized the nZVI. The increased active sites of nZVI and extended interlayer space of Alk-Ti 3 C 2 could improve the uptake capacity of Cr(VI) (194.87 mg/g at pH = 2). The highly efficient removal of Cr(VI) was maintained even in the presence of coexisting cations, which showed great potential for real environment remediation. Mechanistic study indicated that the synergistic effects of nZVI and Alk-Ti 3 C 2 nanosheet in nZVI-Alk-Ti 3 C 2 composites are keys for Cr(VI) removal.
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ENVIRONMENT INTERNATIONAL
·
2019
·
IF 7.943
Shibin Liu,Shengyan Pu,Daili Deng,Hongyan Huang,Chun Yan,Hui Ma,Bahar S. Razavi
Chromium (Cr) contamination is especially hazardous to soil biota. Application of manure and biochar has been frequently proposed to remediate Cr-contaminated soil. However, the understanding of mechanisms behind manure and biochar impacts on soil enzyme activities requires advanced visualization technologies. For the first time, we compared manure and its biochar influence on the spatial distribution of β-glucosidase, N-acetyl-glucosaminidase and phosphomonoesterase activities in Cr-contaminated soil using direct zymography. Maize was planted for 45 days in (a) soil mixed with manure, (b) soil mixed with manure-derived biochar and (c) soil without any addition. Soil pH decreased over 45 days, inducing an increase in acid soluble Cr. The concomitant decrease in β-glucosidase and N-acetyl-glucosaminidase activities explained the narrowing rhizosphere extent of enzyme activities by 13–44%, indicating that increased Cr bioavailability decreases microbial activities. A larger maize performance index and the greatest plant shoot/root ratio after biochar application suggested enhanced maize growth ( p < 0.05). In contrast, manure induced the narrowest extent of β-glucosidase and phosphomonoesterase activities due to the addition of labile organic compounds and nutrients following its application. Our study emphasizes the importance of pH on Cr bioavailability and enzyme activities and demonstrates that biochar application is more ideally suited for remediating Cr-contaminated soil.
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RSC Advances
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2019
·Vol. 9
·期 19
·10958-10965
·
IF 3.049
Yang Zhang,Ruixi Bai,Zhigang Zhao,Qiuxia Liao,Peng Chen,Wanghuan Guo,Chunqing Cai,Fan Yang
In this study, a variety of diglycolic acid-functionalized gold nanoparticle (Au NP) probes are reported, which are highly sensitive for the detection of chromium ions, Cr(VI) ions, at low concentrations in aqueous solutions based on the application of surface plasmon resonance (SPR) theory. Due to its outstanding affinity for Cr(VI) ions, the capped diglycolic acid would induce the aggregation of the NP probes upon encountering them; this was evidenced by the obvious red-shifting of the SPR peak and the enlarged size of the NPs. For the same reason, the selectivity of the probe for Cr(VI) against other heavy metal ions was found to be remarkable. Under optimized conditions, the probe showed the limit of detection (LOD) of 0.32 ppb for Cr(VI) and a linear detection scale ranging from 0.32 ppb to 0.1 ppm. To the best of our knowledge, this is probably the lowest LOD reported for Cr(VI) detection among those of the methods based on SPR.
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APPLIED SURFACE SCIENCE
·
2019
·
IF 5.155
Meirun Li,Chi Song,Ying Wu,Min Wang,Zhepeng Pan,Yang Sun,Liang Meng,Shuguang Han,Lijie Xu,Lu Gan
In the present study, a novel visible-light Z-scheme photocatalyst based on BiOBr/CoFe 2 O 4 /graphene ternary structure was prepared through a hydrothermal approach. The morphology and structure of the prepared photocatalyst were characterized, and the optical properties of the photocatalyst were investigated as well. Afterwards, the photocatalytic performance of the Z-scheme photocatalyst were evaluated through degrading rhodamine B dye and reducing Cr(VI) under visible light irradiation. Compared with pure BiOBr and BiOBr/CoFe 2 O 4 binary composites, the prepared BiOBr/CoFe 2 O 4 /graphene ternary exhibited higher photo-degradation and photo-reduction efficiency. It was also found that the holes were the main active species which were generated during the photocatalysis process. Due to the existence of conductive graphene, the photo-generated active species could be effectively stabilized and quickly transferred. Moreover, the prepared photocatalyst showed very promising recyclable stability, in which the photocatalytic performance of the composites barely decreased after five consecutive circles. The present study provides a new insight in designing and constructing high-efficient and recyclable photocatalyst for aqueous pollutant removal.
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CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Li Song,Fuqiang Liu,Changqing Zhu,Aimin Li
Carboxymethyl cellulose/polyethylenimine hydrogel (CMC/PEI) was firstly prepared with a facile one-step method to enhance Cr(VI) removal. The sufficient hydrogen ions in double-network structure contributed to a high adsorption capacity for Cr(VI) (6.01 mmol g −1 ) especially under mild acidic condition (pH 5). Attenuated total reflection-Fourier-transform infrared (ATR-FTIR) spectroscopy in combination with X-ray photoelectron spectroscopy (XPS) confirmed that Cr(VI) was firstly removed by protonated imine groups through electrostatic attraction, and subsequently reduced to Cr(III) by oxidizing hydroxyl groups. Moreover, in situ generated Cr(III) was well immobilized through coordination with nitrogen and oxygen and precipitation. Furthermore, CMC/PEI could be successfully regenerated and reused, because the adsorption capacity for Cr(VI) was still higher than 2.0 mmol g −1 even after four cycles. Additionally, the highly efficient removal of Cr(VI) was hardly affected by coexisting substances, so CMC/PEI has great potential in practical applications.
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CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Mithun Nath,Shengqiang Song,Hang Liu,Yawei Li
Despite huge potential, Al 2 O 3 –CaO–Cr 2 O 3 system has been one of the least investigated one due to the generation of carcinogenic and toxic Cr(VI) compounds. Herein, we investigated the system under air atmosphere varying Cr 2 O 3 while keeping Al 2 O 3 :CaO ratio constant in order to identify the Cr(VI) dominant region, eventually to avoid it. The Ca 4 Al 6 Cr VI O 16 phase predominantly formed in the air atmosphere with Cr 2 O 3 content up to ∼12 mol%. However, an unprecedented Cr(III) phase appeared under air at higher Cr 2 O 3 content (26.43 mol%). We then synthesized the new polycrystalline ternary Cr(III) compound (CaAl 2 Cr 2 O 7 ) at 1500 °C under air atmosphere for the first time. A trigonal symmetry of hexagonal crystal family with space group P3 (143), lattice parameters a = b = 7.7909 Å and c = 7.6506 Å were determined from the X-ray powder diffraction pattern study. Electron microscope studies revealed uniform hexagonal microcrystals with similar lattice parameters. Most significantly, the binding energies of 586.1 and 576.2 eV for Cr2p 1/2 and Cr2p 3/2 respectively implied the +3 oxidation state of Cr in this compound.
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JOURNAL OF ALLOYS AND COMPOUNDS
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2019
·
IF 4.175
Rongfa Ding,Hui Wang,Yan Jiang,Rui Liu,Ke Jing,Meng Sun,Ruiqian Zhang,Shaoyu Qiu,Zhuoming Xie,Haowei Deng,Xianping Wang,Mingguang Kong,Weibin Jiang,Qianfeng Fang,Changsong Liu
ZrC dispersion-strengthened FeCrAl alloys with enhanced high-temperature strength and good ductility were fabricated through spark plasma sintering (SPS) and hot-forging. Nanosized ZrC particles with an average particle size of 56 nm were homogeneously dispersed in the FeCrAl-ZrC alloys. The addition of a small proportion of ZrC nanoparticles effectively refines the grain size and improves the strength and hardness of FeCrAl alloys. However, the ductility of FeCrAl alloys decreases gradually when the ZrC content increases from 0 wt% to 2.0 wt%. The tensile strength of SPSed FeCrAl-1.0 wt% ZrC alloy at 800 °C is 91 MPa, which is about 69% higher than that of pure FeCrAl, while the percentage elongation after fracture of FeCrAl-1.0 wt% ZrC is 15.0%, which is lower than that of FeCrAl (48.2%). To improve the ductility of FeCrAl-ZrC alloys, the SPSed samples were subjected to hot forging at 1000 °C. Through hot-forging, significant enhancement in ductility of FeCrAl-ZrC alloys was achieved without reducing the strength. The mechanical properties and microstructure of FeCrAl-1.0 wt% ZrC are stable after annealing at 1000 °C for 5 h, exhibiting superior thermal stability as compared with FeCrAl.
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