JOURNAL OF HAZARDOUS MATERIALS
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2021
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IF 10.588
Yibo Yuan,Xipeng Wei,Hua Yin,Minghan Zhu,Haoyu Luo,Zhi Dang
The effects of organic acids on hexavalent chromium (Cr(VI)) removal by reduced iron-based materials have been extensively studied. Nevertheless, the promotion mechanism from the perspective of the electron transfer process is still unclear. Herein, sulfidated nanoscale zero-valent iron (S-nZVI) and the selected organic acids, citric acid (containing both -OH and −COOH groups) and oxalic acid (containing only −COOH groups), showed significant synergistic promotion effects in Cr(VI) removal. The FeS and FeS 2 on S-nZVI surface could enhance the Cr(VI) reduction as the reductive entity and electron conductor. Furthermore, even though the reactivity of FeS with Cr(VI) is higher than that with FeS 2 , the Cr(VI) removal efficiency by FeS 2 was much higher than that by FeS with organic acids. Under neutral and alkaline conditions (pH 6.0–8.0), organic acids promoted the diffusion, adsorption and complexation of Cr(VI) on S-nZVI surface, thus enhancing the electron selectivity towards Cr(VI). However, when the solution pH changed to acidic conditions (pH 4.0), organic acids facilitated the dissolution of Fe(II) ions from S-nZVI and enhanced the electron utilization towards Cr(VI) via the fast Fe(III) reduction process. This study provided a new insight into the Cr(VI) removal, which was beneficial to understand the application boundaries of S-nZVI for Cr(VI) remediation.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
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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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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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Environmental Science-Nano
·
2019
·Vol. 7
·期 1
·286-303
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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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GEOCHIMICA ET COSMOCHIMICA ACTA
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2019
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IF 4.258
Guojun Chen,Yanan Bai,Raymond Jianxiong Zeng,Liping Qin
Chromium isotopes are promising for monitoring and quantifying the extent of microbial Cr(VI) reduction. However, the mechanisms and factors that influence Cr isotope fractionation are not well understood. In the present study, we investigated the effects of different metabolic pathways and various environmental parameters on Cr isotope fractionation during Cr(VI) reduction by the extremely thermophilic bacterium Caldicellulosiruptor saccharolyticus . The Cr isotopic compositions were measured on unreacted Cr(VI) in the remaining solution. The reaction product is isotopically lighter than the reactant. The Cr isotope composition for remaining Cr(VI) in the solution followed a Rayleigh fractionation trend and thus became increasingly isotopically heavier as the reduction of Cr(VI) proceeded. Cr(VI) reduction mainly occurs on the cell surface by Ni–Fe hydrogenase; however, in the presence of CuCl 2 , the activity of Ni–Fe hydrogenase was inhibited, and Cr(VI) was reduced inside the cells. We found that despite different Cr(VI) reduction locations, Cr isotope enrichment factors ( ε = ( α − 1) × 1000, where α is the fractionation factor) were identical within uncertainty for experiments with and without CuCl 2 (−2.72 ± 0.67‰ and −2.92 ± 0.14‰, respectively). When added to the cell cultures, neutral red (NR) functioned as an electron carrier that enabled bacteria to drive the electron transfer processes. The ε values were also similar for experiments with and without NR (−2.53 ± 0.40‰ and −2.92 ± 0.14‰, respectively). We compared these ε values to investigate the effects of different electron transport pathways and cellular Cr(VI) transfer processes, including Cr(VI) transport across the cell envelope and binding to reacting enzymes, on Cr isotope fractionation. Furthermore, the effects of various environmental parameters on Cr isotope fractionation were tested, including temperature (50 °C and 70 °C), hydrogen concentration, and different electron donors (glucose and hydrogen). The ε values were similar at both tested temperatures and stayed within the previously observed range for mesophiles ; changes in hydrogen concentration also did not affect the ε values. However, the ε values were slightly higher with hydrogen as the electron donor (−3.64 ± 0.24‰) than those with glucose as the electron donor (−2.92 ± 0.14‰). In short, the Cr enrichment factors remained unchanged despite of changing microbial Cr (VI) reduction pathways and changing temperature conditions, but may be sensitive to the electron donor type.
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RSC Advances
·
2019
·Vol. 9
·期 19
·10958-10965
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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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CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Qianwei Liang,Sittipranee Ploychompoo,Jingda Chen,Tingting Zhou,Hanjin Luo
Rational design strategy and facile synthesis method of photocatalysts with high efficiency and stability have been still a significant challenge for the removal of environmental contaminants. In this study, a three dimensional (3D) all-solid-state Z-scheme heterojunction photocatalytic system containing bismuth sulphide (Bi 2 S 3 ) and bismuth vanadate (BiVO 4 ) was constructed as Bi 2 S 3 -BiVO 4 graphene aerogel (SVGA) by a facile hydrothermal method. The potential application of as-synthesized SVGA was demonstrated to remove Cr(VI) and bisphenol A (BPA) simultaneously in aqueous media via the synergy of adsorption and photocatalysis under visible light irradiation. The removal rates of Cr(VI) and BPA both nearly reached 100% after adsorption for 40 min and photocatalysis for 120 min under visible light (λ > 420 nm), which was much better than the removal efficiency of individual Bi 2 S 3 and BiVO 4 , as well as Bi 2 S 3 graphene aerogel (SGA) and BiVO 4 graphene aerogel (VGA) samples. The rGO played an important role as photoinduced electron transfer mediator between Bi 2 S 3 and BiVO 4 , which promoted the photogenerated electrons transfer efficiency and enhanced photocatalytic ability of SVGA efficiently. The harmful Cr(VI) was conserved into hypotoxic Cr(III) and BPA was degraded into CO 2 and H 2 O after photocatalysis on SVGA, and the fabricated SVGA also presented favorable stability and satisfactory application effect in practical water samples, implied that such photocatalyst has a promising application for simultaneous removal of heavy metals and organics from aqueous environment.
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CHINESE JOURNAL OF CATALYSIS
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2018
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IF 3.525
Mengli Zhao,Wanni Wang,Chenxi Huang,Wang Dong,Yang Wang,Sheng Cheng,Huiqing Wang,Haisheng Qian
Photocatalysis driven by near-infrared (NIR) light is of scientific and technological interest for exploiting solar energy. In this study, we demonstrate a facile hydrothermal process to synthesize core-shell nanoparticles combining upconversion nanoparticles (UCNPs) and alloyed Zn x Cd 1- x S, which can be excited using NIR or visible light. Morphologies, phase, and chemical composition have been investigated using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction analysis, and atomic absorption spectroscopy. Moreover, we found that amorphous TiO 2 layers existing in the final samples play an important role in formation of UCNPs@Zn x Cd 1- x S yolk-shell nanoparticles, which bind the as-prepared Zn x Cd 1- x S nanoparticles tightly to form yolk-shell nanoparticles. The chemical composition of alloyed Zn x Cd 1- x S can be tunable by adjusting the amount of the Cd and Zn source compounds. The photochemical reduction of Cr(VI) in water has been performed to study the photocatalytic performance under irradiation by NIR light or a simulated solar light, showing efficient photoreduction and Cr(VI) removal over the as-prepared UCNPs@Zn x Cd 1- x S/TiO 2 yolk-shell nanoparticles. The as-prepared UCNPs@Zn x Cd 1- x S/TiO 2 nanoparticles show excellent production of hydroxyl radicals, which are responsible for the photochemical reduction of Cr(VI) to Cr(III). This study will provide an alternative strategy for environmental wastewater treatment , making full use of solar energy.
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