CHEMOSPHERE
·
2021
·
IF 7.086
Wenzhi Gu,Decong Zheng,Daping Li,Cuicui Wei,Xu Wang,Qingzhuoma Yang,Chang Tian,Mengyao Cui
In controlling toxic Cr(Ⅵ) pollution, the sulfate-reducing bacteria (SRB) method—a bioresource technology—is considered more sustainable and stable than synthetic technologies; however, its mechanisms of metal removal are unclear. This study investigated the mechanism of the use of citrate as a carbon source in an SRB bioreactor for Cr(Ⅵ) removal by disassemble or simulation approach. We show that citrate can mask toxicity, whereby the IC 50 value (inhibitory concentration affecting 50% of the test population) of citrate was higher than that of lactate, and that citrate can also protect water systems from oxidation. The anti-oxidation rate of citrate ranged from 76.00% to 90.92%; whereas for citrate‒Cr(Ⅲ), the oxidation rate was only 0.185%–0.587%. Citrate can up-regulate microbial genes and functions, causing acetate and sulfide (NaFeS 2 ) accumulation. Acetate addition promoted Cr adsorption by sulfide (mainly NaFeS 2 ) and promoted sulfide sedimentation. Moreover, in addition to Cr(Ⅵ) reduction and Cr(Ⅲ)‒sulfide generation, the addition of sulfide promoted sedimentation; the correlation coefficient between the sedimentation coefficient and the sulfur content was r = −0.88877 at p < 0.01. Therefore, citrate had a systemic radiative effect on every aspect of the SRB‒citrate system model for Cr(Ⅵ) removal. In addition to the reduction in the former simple model, an integrative effect (including adsorption, sedimentation, and metabolism) was combined with NaFeS 2 for Cr removal, which was regulated by the SRB‒citrate system. Exploration and understanding of these mechanisms promote SRB‒citrate methods to be wider implications in practice.
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Environmental Technology & Innovation
·
2025
·
IF 7.1
Yonglin Yang,Jiangyong He,Shuaige Shi,Long Yan,Jian Li,Xiaoyong Fan,Bi Chen,Guohui Dong,Hongrui Ma
There is a key issue about formation of highly toxic and easily dissoluble Cr(VI) during heat treatment of Cr-bearing solid waste, resulting in a prominent increase of environmental risk of incineration product. In this study, the effects of CaO and SiO 2 on formation and reduction of Cr(VI) were investigated during heating of Cr-bearing simulated sludge (Cr-SS) and Cr 2 O 3 , exploring Cr(III) oxidation mechanism. The findings indicates that doping CaO significantly promotes Cr(III) oxidation to Cr(VI), and chromium speciation vary with temperature. At 300℃, leaching amount of Cr(VI) in Cr-SS samples increases sharply to 9.3 % of total Cr. In contrast, no Cr(VI) was detected in Cr 2 O 3 samples. Above 300℃, oxidation rates of Cr(III) in different samples of Cr-SS and Cr 2 O 3 exhibit the same trend with temperature increasing. Above 1000℃, new Cr-containing crystalline phases were observed, like CaCr 2 O 4 and Ca 3 (CrO 4 ) 2 . The oxidation rate of Cr(III) is positively connected with the adding amount of CaO. Besides, doping SiO 2 to sludge prominently inhibits Cr(III) oxidation or facilitate Cr(VI) reduction at 600℃-1200℃, which is also confirmed by thermodynamic calculation, attributing to formation of Ca 5 Cr 2 SiO 12 and CaCr 2 O 4 . The number of holes in valence band will be changed through substitution of Cr(III) ions by cations of different valence states, thus facilitate or inhibit Cr(III) oxidation. The ions (III) can inhibit Cr(III) oxidation and promote Cr(VI) reduction. Introducing SiO 2 or Si-enriched materials to chromium-bearing wastes may be a promising alternative to solve the problem of highly toxic Cr(VI) formation during heat treatment.
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MICROCHIMICA ACTA
·
2022
·Vol. 189
·期 12
·1-10
·
IF 6.408
An Yingying,Wang Wan,Lv Qing,Zhang Qing,Wang Xiayan
A paper-based analytical device (PAD) is presented with colorimetric/electrochemical dual readouts for the simultaneous sensing of total chromium (Cr) and hexavalent chromium (Cr(VI)). This device consists of a homemade three-electrode system and a patterned paper chip, integrating multiple functions including electrochemical detection, fluid driving, online oxidation, and colorimetric detection. The fiberglass filter paper with a hydrophilic microchannel was used to achieve self-driving fluidics without external equipment. One end of the microchannel was integrated with a homemade three-electrode system to achieve sample loading and electrochemical detection. The middle region on the microchannel was modified with oxidizing reagents to perform online pretreatment, and the yield of Cr(III) oxidation can reach 97.9%, ensuring reliable colorimetric detection of total Cr at another end of the microchannel modified with chromogenic agents. With this device, the signals of Cr(VI) (the signal peak at 0.29 V vs. Ag/AgCl) and total Cr can be obtained in one single injection. After optimization, the limit of detection (LOD) of Cr(VI) and total Cr were 0.01 mg L −1 and 0.06 mg L −1 and the linear ranges were 0.05–3.0 mg L −1 and 0.2–3.0 mg L −1 , respectively. The relative standard deviations (RSD) of the electrochemical testing of Cr(VI) results were in a range 1.3%–8.7% ( n = 3), and the RSD values of the colorimetric testing of total Cr were between 0.7–9.2% ( n = 3). The device’s reliability was demonstrated by performing the practical speciation of Cr in tap water, river water, and electroplating wastewater while the recoveries obtained using the present method were in the range 93.5–106%. Overall, the proposed device provides high application prospect in the on-site rapid Cr speciation. Graphical abstract
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2020
·Vol. 27
·期 14
·16745-16753
·
IF 3.056
Yu Cheng,Zhang Yi,Fang Yu,Tan Yujie,Dai Ke,Liu Shilin,Huang Qiaoyun
Shewanella oneidensis MR-1 (MR-1)-impregnated alginate capsules with 3D porous structure were prepared through cation crossing-linking and was used for the Cr(VI) reduction and removal. After being encapsulated by alginate, the endurance of the MR-1 was largely enhanced under conditions of high Cr(VI) concentrations (up to 4 mM) and low pH (pH 5). The Cr(VI) reduction over the MR-1-impregnated alginate capsules could be fitted by pseudo first-order kinetic model. With the Cr(VI) initial concentration increasing from 1 to 4 mM, the first-order rate constant for the encapsulated MR-1 ( k capsules ) and free cells ( k cells ) fell by 26.3% and 82.4%, respectively. At pH 5, the k capsules value was 0.19 h − 1 , which was about 3.7 times higher than k cells . Moreover, the encapsulated MR-1 held 90.5% of the Cr(VI) reduction ability after 15 days of resting time, while the free MR-1 held 19.7%. After bioreduction, 73.6% of total chromium was adsorbed on the MR-1 impregnated Ca-alginate capsules. XPS results showed 85% of the adsorbed chromium was Cr(III). The mechanism for chromium removal over the MR-1-impregnated Ca-alginate capsules was proposed with the following steps: (1) Cr(VI) was bioreduced via the encapsulated MR-1; (2) the reduced soluble Cr(III) was adsorbed by alginate selectively. In the study, the Ca-alginate shell of the cabbage-like MR-1 impregnated capsules could be a shelter for encapsulated MR-1 to endure unfavorable conditions (e.g., low pH and high concentration of Cr(VI)) and immobilize the soluble chromium. Considering the obtained capsules derived from biomolecules were environment-friendly, the MR-1-impregnated Ca-alginate capsules were potential for the application in the remediation of environmental pollution.
Graphical abstract
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DALTON TRANSACTIONS
·
2018
·Vol. 48
·期 3
·989-996
·
IF 4.099
Ling Yang,Tian Zhao,Ishtvan Boldog,Christoph Janiak,Xiao-Yu Yang,Qiang Li,Yan-Jia Zhou,Yong Xia,Deng-Wang Lai,Yue-Jun Liu
The concentration of benzoic acid was found to exercise efficient control over the formation of either MIL-101(Cr) or MIL-88B(Cr) under otherwise similar hydrothermal synthetic conditions. Nanocrystals of MIL-101(Cr) with ∼100 nm average size and excellent SBET = 3467 m2 g−1 are obtained at lower concentrations of benzoic acid, while at higher concentrations the microparticulated MIL-88B(Cr) product is formed. Hereby a new efficient synthetic method towards the elusive MIL-88B(Cr), yet reported only once without synthetic details, is proposed. The obtained MIL-88B(Cr) has an interesting and potentially valuable property of retaining its high-volume form (Vcell ∼ 2000 Å3) after thermal activation. The degassing of MIL-88B(Cr) in a vacuum at 250 °C yields a porous material with a SBET area of 1136 m2 g−1, which is around the theoretical maximum. The transition to the denser ‘closed’ form (Vcell ∼ 1500 Å3) occurs only at 350 °C, when all of the benzoate/benzoic acid, hindering the process, is removed.
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SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Chengfang Zhang,Zhenyu Song,Chao Li,Qinglong Liu,Jingchun Tang
In the actual polluted environment, the composite pollution system was usually composed of heavy metals and organic pollutants, especially Cr(VI) and chlorophenols often co-existed in industrial wastewater. In this study, a composite material consisting of multilayer graphene carbon shells coated with nZVI (gBC@nZVI) with various excellent properties was applied to deal with the composite system of Cr(VI) and 2,4-dichlorophenol (2,4-DCP) coexisting in the wastewater, and the intrinsic mechanism for the simultaneous removal of heavy metals and organic pollutants was systematically investigated. The results showed that in the composite pollution system (Cr(VI) = 20 mg/L, 2,4-DCP = 15 mg/L), complete removal of Cr(VI) could be achieved in 60 min, while 2,4-DCP achieved 95.2 % removal, with the contribution of oxidative degradation being 76.4 %. It was found that during the efficient adsorption and reduction of Cr(VI) by gBC@nZVI, the generation of the metastable intermediate Cr(V) was verified by probe compounds, electron spin resonance and UV–visible spectroscopy, and further experiments demonstrated that the generation of •OH was closely related to Cr(V) and promoted the oxidative degradation of the coexisting 2,4-DCP. Quenching experiments with the addition of specific scavengers indicated that •OH was the active species directly dominating the oxidative degradation of 2,4-DCP, whereas Cr(V) was indirectly involved in the degradation of 2,4-DCP by promoting the generation of •OH. In addition, the increase of solution pH negatively affected the degradation of 2,4-DCP in the composite polluted system, mainly due to the hindered generation of •OH in the alkaline environment. This work provided theoretical support for the promising application of gBC@nZVI in real environments contaminated with a combination of Cr(VI) and chlorophenols.
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2023
·
IF 8.2
Peiyuan Xiao,Junqing Xu,Hongliang Shi,Fengyang Du,Huanzheng Du,Guangming Li
The simultaneous reduction of Cr(VI) and sequestration of the resulting Cr(III) in one process is highly desirable as a cost-effective and environmental-friendly approach for the decontamination of Cr(VI)-polluted wastewater. However, most of the existing adsorptive materials are only effective in low pH environments (pH = 1–3), severely restricting the adsorption efficiency and cost effectiveness. Herein, we proposed a chitosan-based magnetic porous microsphere (PPy@PMCS) for simultaneous Cr(VI) reduction and Cr(III) sequestration in a wide pH range. Benefiting from its abundant interaction sites, Cr(VI) was effectively adsorbed on the surface and then immediately reduced to Cr(III) with much lower toxicity. Most importantly, the resulting Cr(III) was in-situ sequestrated by the complexation of chitosan matrix. As a result, PPy@PMCS exhibited a maximum Cr(VI) adsorption capacity of 330.42 mg/g at pH 2.0 and an adsorption capacity of 167.82 mg/g even at near neutral pH (6.0), which is superior to most reported adsorbents. Furthermore, the exhausted PPy@PMCS can be rapidly separated from solutions under an external magnetic field and facilely regenerated. The proposed novel biopolymer-based material shows great application potentials in wastewater treatment.
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MOLECULES
·
2019
·Vol. 24
·期 20
·3718
·
IF 3.06
Mao-Long Chen,Shu-Yang Zhou,Zhou Xu,Li Ding,Yun-Hui Cheng
MIL-100(Fe, Cr) and MIL-101(Cr) were synthesized by the hydrothermal method and applied to the adsorptions of five aromatic amines from aqueous solutions. These three metal-organic frameworks (MOFs) were well characterized by powder X-ray diffraction (PXRD), scanning electron microscope (SEM), transmission electron microscope (TEM), thermogravimetric analysis (TGA) and surface area analysis. The adsorption mechanism of three MOFs and the effects of the structures of MOFs on the adsorption of aromatic amines were discussed. The results show that the cavity system and suitable hydrogen bond acceptor were important factors for the adsorption for five aromatic amines of aniline, 1-naphthalamine, o-toluidine, 2-amino-4-nitrotoluene and 2-nitroaniline: (a) the saturated adsorption capacity of aniline, 1-naphthylamine and o-toluidine on MIL-100(Fe) were 52.0, 53.4 and 49.6 mg/g, respectively, which can be attributed to the intermolecular hydrogen bond interaction and cavity system diffusion. (b) The adsorption capacity of 2-nitroaniline and 2-amino-4-nitrotoluene on MIL-101(Cr) were 54.3 and 25.0 mg/g, respectively, which can be attributed to the more suitable pore size of MIL-101(Cr) than that of MIL-100(Fe, Cr). The MOFs of MIL-100(Fe) and MIL-101(Cr) can be potential materials for removing aromatic amines from aqueous solutions.Keywords:metal-organic framework;adsorption;aromatic amines;aniline;1-naphthalamine;o-toluidine;2-amino-4-nitrotoluene;2-nitroaniline
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JOURNAL OF MOLECULAR LIQUIDS
·
2017
·
IF 3.648
Qianwei Liang,Junjie Geng,Hanjin Luo,Wei Fang,Yuwei Yin
In the present study, a novel magnetic Cr(VI) ion-imprinted polymer (MGOIIP) was prepared by a sol-gel process for fast and selective adsorption of Cr(VI) anions from aqueous solutions. In the synthesis process, 4-vinyl pyridine (4-VP) and 2-hydroxyethyl methacrylate (HEMA) were used as functional monomer and co-monomer; ethylene glycol dimethacrylate (EGDMA) and N , N -azoisobisbutyronitrile (AIBN) were used as cross-linker and initiator, respectively; acetone was selected as solvent. Fe 3 O 4 @SiO 2 nanoparticles were introduced for separating adsorbents from the aqueous solution conveniently, and graphene oxide (GO) could prevent Fe 3 O 4 @SiO 2 particles from aggregating. Some different techniques including Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), SEM-energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to confirm the successful synthesis of ion-imprinted polymer on the surface of Fe 3 O 4 @SiO 2 /GO nanoparticles. The obtained magnetic ion-imprinted polymer has a high adsorption capacity (up to 311.95 mg/g) for Cr(VI) anions at an optimal pH of 2.0, and the adsorption equilibrium can be reached within 3 min. The adsorption process can be fitted well with Langmuir isotherm model and the pseudo-second-order kinetic model . Moreover, the results showed that MGOIIP has excellent selectivity and good regeneration ability. The prepared MGOIIP exhibited a satisfactory recovery for Cr(VI) anions in tap, river and lake water samples.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2016
·
IF 3.976
Zunwei Chen,Shufang Song,Yuezhong Wen
The priority pollutant chromium (Cr) was ubiquitous and great efforts have been made to reduce Cr (VI) into less-toxic Cr (III) by alga for the convenient availability and low expense. However, the functional role of organelle inside the algal cell in Cr (VI) reduction was poorly understood. In this study, organelles in green algae Chlorella vulgaris were extracted and further decorated for Cr (VI) reduction tests. Results showed that the chloroplast exhibited not only adsorption ability of total Cr (21.18% comparing to control) but also reduction potential of Cr (VI) (almost 70% comparing to control), whose most suitable working concentration was at 17 μg/mL. Furtherly, the isolated thylakoid membrane (ITM) showed better Cr (VI) reduction potential with the presence of sodium alginate (SA), even though the Hill reaction activity (HRA) was inhibited. As for photosystem II (PSII), the addition of mesoporous silica SBA-15 enhanced the reduction ability through improving the light-harvesting complex (LHC) II efficiency and electron transport rate. On the whole, the reduction ability order of the three kinds of materials based on chloroplast in C. vulgaris was PSII@SBA-15 > Chloroplast > ITM@SA. The attempt made in this study to reduce the Cr (VI) with C. vulgaris organelles might not only offer basement to detect the potential action mechanism of Cr (VI) reduction by C. vulgaris but also provide a new sight for the scavenge of heavy metal with biological materials.
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REACTIVE & FUNCTIONAL POLYMERS
·
2020
·
IF 3.333
Jiahong Wang,Min Mao,Saleem Atif,Yao Chen
The presence of widely used chelating agents such as ethylenediaminetetraacetic acid (EDTA) in aqueous solution increases the difficulty of heavy metal removal by the formation of heavy metal chelates. In this study, diethylenetriaminepentaacetic acid (DTPA)-chitosan functionalized magnetic silica (Fe 3 O 4 @SiO 2 /Cs-DTPA) was developed for the removal of Cr(III) and Cr(III)-EDTA. The obtained results from characterization confirmed that Fe 3 O 4 @SiO 2 /Cs-DTPA with the core-shell structure and superparamagnetic properties was synthesized. The maximum theoretical adsorption capacity of Cr(III) and Cr(III)-EDTA chelates on the adsorbents were 39.27 and 22.24 mg/g at 25 °C and pH 4.0, respectively. Adsorption equilibrium of Cr(III) and Cr(III)-EDTA on Fe 3 O 4 @SiO 2 /Cs-DTPA was achieved within 15 min, and the adsorption data fit the pseudo second-order model. The co-existing complex agents (EDTA) and cations (Na + , Ca 2+ , and Mg 2+ ) in the aqueous solution reduced Cr(III) adsorption by the competition with Cr(III) and Cr(III)-EDTA chelate for active groups of the adsorbent. The affinity of the Fe 3 O 4 @SiO 2 /Cs-DTPA for Cr(III) and Cr(III)-EDTA was excellent even at high salt and organic chelates concentration. The Cr(III) adsorption was attributed to surface complexation between Cr(III) and DTPA moieties of the adsorbent, while Cr(III)-EDTA as a whole was adsorbed on the adsorbent by the complexation and electrostatic interaction . Cr(III) saturated Fe 3 O 4 @SiO 2 /Cs-DTPA can be readily regenerated in acid solution and Cr(III) or Cr(III)-EDTA adsorption of regenerated adsorbent exhibits no obvious reduce.
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MICROCHIMICA ACTA
·
2020
·Vol. 187
·期 7
·1-11
·
IF 6.232
Guo Hao,Wu Ning,Xue Rui,Liu Hui,Wang Mingyue,Yao Wenqin,Wang Xiaoqiong,Yang Wu
An Eu(III)-functionalized strontium-organic framework (Eu 3+ @Sr-MOF) was synthesized by encapsulating Eu 3+ ions into the pores of Sr-MOF via postsynthetic modification (PSM) and fully characterized by XRD, SEM, EDS, FTIR, and TGA. The luminescent properties of Eu 3+ @Sr-MOF were measured and investigated in detail, which demonstrated that Eu 3+ @Sr-MOF not only possessed excellent water and chemical stabilities in a wide pH range (5–10) but also displayed red luminescence with excitation/emission maxima at 332/617 nm. The Eu 3+ @Sr-MOF can be considered as a highly selective and sensitive recyclable luminescence probe for sensing Cr(III) and Cr(VI) based on strong luminescence quenching effects; it can be recycled at least five times. The luminescence probe for Cr 3+ , CrO 4 2− , and Cr 2 O 7 2− shows low detection limits (0.15 μM, 0.17 μM, and 0.13 μM, respectively), relatively broad linear ranges (0.6–150 μM, 0.1–200 μM and 0.4–180 μM, respectively), and high quenching constants K SV . The signals can be observed by the naked eye under UV light of 365 nm. The method was applied to the determination of total Cr in environmental water samples.
Graphical abstract
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危险品化学品经营许可证（带存储）