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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高影响因子
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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JOURNAL OF ALLOYS AND COMPOUNDS
·
2021
·
IF 5.316
Xinyu Hu,Juntao Wang,Jing Wang,Kehui Xue,Ting Yang,Yi Peng,Ying Yan,Hongbo Xiao,Wenlei Wang
Controlling the migration behavior of photogenerated carriers by designing the microstructure of materials remains a significant challenge. In this work, the solvothermal method was used to fabricate a SnO 2 /SnS 2 heterojunction anchored on biochar through −C Sn− bonds between biochar and SnS 2 , as demonstrated by X-ray photoelectron spectroscopy characterization. DFT calculations further confirmed −C Sn− bonds can shorten theoretical band gap of SnS 2 @biochar from 1.01 eV to 0.66 eV and provide a pathway for swift electron migration, which can effectively modulate the separation of photo-induced carriers and promote the generation of e − and h + . Additionally, the oxalate activated by −C Sn− bonds can effectively capture h + and produce abundant ∙CO 2 – free radicals. When the obtained composites were used as photocatalysts , Cr(VI) was thoroughly reduced by the SnO 2 /SnS 2 @biochar composite with a molar ratio of SnO 2 and SnS 2 of 2 within 20 min under visible light irradiation when oxalate was 1.0 mM (CSO-2/H 2 C 2 O 4 -1). Furthermore, CSO-2/H 2 C 2 O 4 -1 exhibited excellent reusability, and the degradation efficiency of Cr(VI) remained above 91.71% after five cycles. The remarkable photocatalytic properties can be ascribed to the synergistic effects of e − and ∙CO 2 – . This work proposes a new strategy for the preparation of an applied photocatalyst with a high separation rate of photoinduced carriers.
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高影响因子
LANGMUIR
·
2019
·
IF 3.683
Fei Xue,Hui He,Hongxiang Zhu,Huanhuan Huang,Qi Wu,Shuangfei Wang
A cellulose-based solid amine adsorbent (MCC/TEPAA) with high amino density for the detection and removal of Cr(VI) was designed and prepared through using epichlorohydrin cross-linking with MCC (microcrystalline cellulose) and tetraethylenepentamine (TEPA). The structure and amino density of the cellulose-based solid amine adsorbents could be tailored by adjusting the structure of the amines (triethylenetetramine or diethylenetriamine). The as-prepared cellulose-based solid amine adsorbents could detect and completely remove Cr(VI) from water, and the concentration of Cr(VI) solution after adsorption met the standard concentration of Cr(VI) solution for drinking water (0.05 mg/L). In particular, the MCC/TEPAA, supported by MCC with porosity as a framework, promoted the adsorption rate (adsorption equilibrium within only 10 min), removal rate (100%) of Cr(VI), and adsorption capacity (327.72 mg/g). In addition, the limit of colorimetric detection of Cr(VI) by MCC/TEPAA was 0.5 mg/L at 20 min when other interfering heavy metal ions exist. The adsorption and colorimetric detection mechanism of Cr(VI) on MCC/TEPAA was proposed to include electrostatic interactions, chelating reactions, and oxidation–reduction reactions, all of which contributed to the excellent adsorption and detection performance.
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CELLULOSE
·
2019
·Vol. 26
·期 5
·3437-3453
·
IF 3.917
Zhang Shengli,Chen Haoyu,Zhang Silue,Kai Chengcheng,Jiang Man,Wang Qun,Zhou Zuowan
Abstract A novel biosorbent PEI-HOCM was successfully prepared by grafting polyethyleneimine (PEI) onto H 2 O 2 -oxidized cellulose membrane (HOCM). The whole systhesis process occurred in aqueous solution and was environmentally friendly without any toxic cross-linkers involved. ATR-FTIR, XPS and titration analysis confirmed that the hydroxyl groups of cellulose were oxidized to carbonyl groups by H 2 O 2 and PEI was successfully introduced to the HOCM. The PEI-HOCM had positively charged surface (+ 20.6 to + 86.6 mV) at the measured pH range 3–9 according to the zeta potential analysis. The adsorption of Cr(VI) on the PEI-HOCM obeyed the pseudo-second-order kinetic model and Langmuir isotherm model. Its maximum equilibrium adsorption capacity was 147.06 mg/g at 25 °C, which was much higher than that of cellulose membrane (CM, 30.61 mg/g). According to the obtained results from the intraparticle diffusion, Body kinetic and diffusion-chemisorption models, film diffusion was the rate-limiting step and chemical adsorption was the main mechanism of Cr(VI) adsorption. The Cr(VI) adsorbed on the PEI-HOCM was completely reduced to Cr(III), suggesting that PEI-HOCM was not only useful for Cr(VI) removal but also good for its detoxification. The competitive uptakes from coexisting components (Na + , Mg 2+ , Ca 2+ , phenol, Cl − and NO 3 − ) were insignificant except H 2 PO 4 − and SO 4 2− which reduced the Cr(VI) uptake with a efficiency loss of 22–41%. Ionic strength had little effect on the adsorption in the range of 0–1000 mg/L NaCl. After five adsorption/desorption cycles, the PEI-HOCM still retained good adsorption capacity. More importantly, it can be separated easily after adsorption, which will greatly benefit the wastewater treatment by simplifying the separation procedure and reducing costs. Graphical abstract
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ENVIRONMENTAL TECHNOLOGY
·
2019
·
IF 1.918
Ying Li,Cheng Chen,Yao Wu,Yijie Han,Yeqing Lan
The synergism of CuS and tartaric acid (TA) in the reduction of Cr(VI) with an irradiation of simulated solar light was investigated through observing the effects of solution pH, temperature, CuS loading and TA concentration on the removal efficiency of Cr(VI). Approximately 32% and 54% of the initial Cr(VI) (100 µmol/L) were reduced within 180 min by TA and CuS with light, respectively. Under the same condition, however, almost a complete removal of the initial Cr(VI) was achieved within 130 min in the coexistence of CuS and TA. In the case, it is considered that Cr(VI) was rapidly reduced in two main pathways. One is that H2S produced from the dissolution of CuS in weak acidic solution directly reduced Cr(VI) to Cr(III). The other is that Cu(II) released from CuS reacted with TA to form complexes with photochemical activity, producing Cu(I) through ligand-to-metal electron transfer, and then the reduction of Cr(VI) was coupled with a conversion of Cu(I) to Cu(II). Thus, a cycle catalytic system was established for the reduction of Cr(VI). Moreover, it is observed that the reaction could be divided into two stages: the initial chemical reduction of Cr(VI) by H2S and the later photochemical reduction of Cr(VI) by Cu(II)–TA complexes.
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ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2019
·Vol. 26
·期 28
·28898-28908
·
IF 2.914
Zhang Yakun,Chen Sisi,Feng Xuezhen,Yu Jingang,Jiang Xinyu
The assembly of graphene oxide with biomass or polymers to form 3D hydrogels with excellent mechanical properties has become a research hotspot. In this work, the sponge-like kaolin/chitosan (CS)/reduced graphene oxide (rGO) composite was prepared for adsorption by simple self-assembly without cross-linking agent. The morphology, composition, surface properties, and pore size of as-prepared materials were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), zeta potential analyzer, Brunauer-Emmett-Teller surface area measurement (BET), and scanning electron microscopy (SEM). The effects of raw material ratio, contact time, temperature, pH, ionic strength, and recycling times on adsorption performance were investigated in detail. The results indicate that the composite has good absorption capacity for Cr(VI) and alizarin yellow R (AYR). Besides, composite hydrogel also exhibits excellent flexibility and good repeatability, which confirms its great potential as an adsorbent to remove pollutants in the water environment.
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