APPLIED CLAY SCIENCE
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2020
·
IF 4.605
Zhenyuan Li,Zhidong Pan,Yanmin Wang
A ternary nanocomposite integrating polyethyleneimine (PEI), magnetite (Fe 3 O 4 ) nanoparticles , and illite/smectite clay nanoflakes (denoted as PEI-MI/S) was prepared via a mechanochemical route in a high-energy density stirred bead mill. The ternary PEI-MI/S nanocomposite was determined by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetry , scanning electron microscopy, transmission electron microscopy , vibrating sample magnetometry and X-ray photoelectron spectroscopy, respectively. The results show that ternary PEI-MI/S nanocomposite can be prepared in the presence of intense grinding , which can graft a more amount of PEI rather than that prepared in the absence of grinding. The compressive and shear stresses in intense grinding can disperse Fe 3 O 4 nanoparticles and exfoliate/destruct I/S clay nanoflakes. Also, the mechanochemical effect facilitates the hydrogen bond and electrostatic interaction between PEI and magnetic I/S, and the crosslink reaction between PEI and glutaraldehyde in grinding, resulting in a more grafting amount of PEI. Ternary PEI-MI/S nanocomposite was applied for the removal of hexavalent chromium (Cr(VI)) anions in aqueous solution. The effect of parameters (i.e., pH value, adsorption time, temperature, and initial concentration of Cr(VI) anions) on the adsorption performance was investigated. It is indicated that the adsorption of Cr(VI) anions onto PEI-MI/S nanocomposite be related to the adsorption/reduction process. Ternary magnetic PEI-MI/S nanocomposite with a saturated magnetization (Ms) of 14.7 emu/g facilitates the magnetic separation and reusability . The regenerated ternary PEI-MI/S nanocomposite can maintain 71.43% of initial activity for adsorption of Cr(VI) anions after 6 cycles.
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Catalysts
·
2020
·Vol. 10
·期 4
·453
·
IF 3.52
Emmanuelia Akimana,Jichao Wang,Natalya V. Likhanova,Somboon Chaemchuen,Francis Verpoort
Mild reaction conditions (nearly room temperature and atmospheric CO2pressure) for the cycloaddition of CO2with epoxides to produce cyclic carbonates were investigated applying MIL-101(Cr) as a catalyst. The MIL-101 catalyst contains strong acid sites, which promote the ring-opening of the epoxide substrate. Moreover, the high surface area, enabling the adsorption of more CO2(substrate), combined with a large pore size of the catalyst is essential for the catalytic performance. Additionally, epoxide substrates bearing electron-withdrawing substituents or having a low boiling point demonstrated an excellent conversion towards the cyclic carbonates. MIL-101(Cr) for the cycloaddition of carbon dioxide with epoxides is demonstrated to be a robust and stable catalyst able to be re-used at least five times without loss in activity.Keywords:MIL-101;heterogeneous catalyst;CO2cycloaddition;carbonate;ambient conditions
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JOURNAL OF HAZARDOUS MATERIALS
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2020
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IF 9.038
Weitian Cai,Dionysios D. Dionysiou,Fenglian Fu,Bing Tang
The treatment of heavy metal pollution in aquatic environment, especially the pollution caused by multiple heavy metal ions, has been a growing global concern for decades. To address this problem, it is urgent to explore effective and low cost adsorbents which can remove multiple heavy metal ions simultaneously. Herein, Cr(VI) and Ni(II) removal from water by MoS 2 with widened interlayer spacing was systematically investigated in comparison with pure MoS 2 . A series of techniques, including X-ray powder diffraction (XRD), Transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET) surface area and porosimetry analysis were applied to characterize the nanocomposites. The XRD results confirmed the enlarged interlayer spacing of MoS 2 by intercalating cetyl trimethyl ammonium bromide (CTAB) into the interlamination. The maximum adsorption capacities of Cr(VI) and Ni(II) for MoS 2 /CTAB were 79.4 mg g −1 and 88.3 mg g −1 , respectively. Moreover, a synergistic effect in the simultaneous removal of Cr(VI) and Ni(II) was observed. A new Cr(VI) removal mechanism involving redox reaction between Cr(VI) and Mo(IV) in MoS 2 /CTAB was verified. The removal efficiencies of Cr(VI) and Ni(II) still remained high at the end of fifth cycle, indicating that MoS 2 /CTAB has a great potential to remove heavy metals from wastewater.
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SCIENCE OF THE TOTAL ENVIRONMENT
·
2020
·
IF 6.551
Manjun Deng,Xuejiang Wang,Yuan Li,Fei Wang,Zhuwu Jiang,Yiyang Liu,Zaoli Gu,Siqing Xia,Jianfu Zhao
In this study, an industrial waste-blast furnace slag (BFS) supported sulfidized nanoscale zerovalent iron (S-nZVI@BFS) was prepared and used for synergistic reduction and adsorptive removal of Cr(VI) from aqueous solutions. The characterization analysis showed that Fe 0 and FeS were well dispersed on the surface of BFS, and the specific surface area of S-nZVI@BFS was 141.986 m 2 g −1 . Batch experiments demonstrated that the removal capacity of Cr(VI) was as high as 184 mg/g for S-nZVI@BFS. The pseudo-second-order kinetic model fitted the Cr(VI) removal kinetics well. Cr(VI) removal on the S-nZVI@BFS relied highly on pH values. The reduced Cr(VI) precipitated on S-nZVI@BFS mainly as Cr x Fe (1-x) (OH) 3 , Cr x Fe (1-x) OOH and Cr 2 S 3 , and the alkaline capacity of the BFS could efficiently prevent the release of Cr(III) from the precipitations in acid condition. Thus, supporting S-nZVI on BFS was an effective and safe method for Cr(VI) removal from aqueous solutions.
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JOURNAL OF HAZARDOUS MATERIALS
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2020
·
IF 9.038
Guangda Yu,Fenglian Fu,Chujia Ye,Bing Tang
The mobility of Cr(VI) in the environment is affected by the transformation of ferrihydrite (Fh) and ferrihydrite-humic acid co-precipitates (Fh-HA). However, the impacts of Fe(II)-induced transformation of Fh and Fh-HA on the mobility, speciation and partitioning of associated Cr(VI) remain unclear. In this study, the behaviors of adsorbed Cr(VI) during Fh and Fh-HA aging at 70 °C for 9 days (pH 0 = 3.0 and 7.0) in the absence and presence of Fe(II) were studied. Results revealed that the main speciation of Cr(VI) after transformation was non-desorbable Cr and its formation involved the following pathways. Firstly, Fe(II) (0.2 and 2.0 mM) induced the transformation of Fh-HA to hematite and goethite, promoting the structural incorporation of adsorbed Cr into hematite and goethite via complexation. Secondly, under neutral condition (pH 0 = 7.0), the low concentration of Fe(II) (0.2 mM) could not reduce completely Cr(VI) to Cr(III) and thus residual Cr(VI) was incorporated into the Cr(III)-Fe(III) co-precipitates. Thirdly, coprecipitated humic acid not only reduced Cr(VI) to Cr(III) via polysaccharide, but also formed complexes with incorporated Cr through carboxylic groups to sequester Cr. Our results demonstrate that Fe(II)-induced transformation of Fh-HA exerts major influences on associated Cr(VI) speciation and partitioning.
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Journal of Central South University
·
2021
·Vol. 28
·期 6
·1652-1664
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IF 1.716
Jiang Chun-lu,Wang Rui,Chen Xing,Zheng Liu-gen,Cheng Hua
Chitosan-coated fly ash (CWF) was prepared by the acid leaching-coating method. Chitosan and fly ash were crosslinked in the solution of acetic acid and sulfuric acid. The microstructure of CWF was conducted by scanning electron microscope (SEM) and X-ray diffraction (XRD). The removal of Cr(VI) from water by CWF was studied by adsorption experiments. The composite prepared by the experiment developed a pore structure and a crystal structure similar to SiO 2 and chitosan chain-like coating was formed on the surface of fly ash. The new modified material has larger surface roughness, specific surface area and more adsorption channels. The Cr(VI) was enriched in modified materials by electrostatic adsorption between CrO 4 2− , CrO 7 2− and —NH 3 + group and surface acid functional groups. The movement of Cr(VI) in solution is a diffusion process from the main body of the liquid phase to the surface of the liquid film.
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Journal of Cleaner Production
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2021
·
IF 9.297
Liji Bai,Xiujuan Su,Jinpeng Feng,Shaojian Ma
In this study, a sugarcane bagasse biochar/nano-iron oxide composite was prepared via a one-pot pyrolysis method by using the sugarcane bagasse-based solid waste and microwave as the raw material and energy source, respectively. The developed composite was characterized by BET, XRD , FT-IR and TEM and was applied for the removal of Cr (VI) from water. The composite was observed to be mainly composed of amorphous carbon , Fe 3 O 4 and Fe 2 O 3 . The iron oxides were uniformly embedded on the surface of the carbon layer by van der Waals force . The sugarcane bagasse-based biochar/nano-iron oxide composite material exhibited an optimal Cr (VI) adsorption capacity of 55 mg/g under the experimental conditions specified in this study. The Cr (VI) adsorption mechanism of the Fe 2 O 3 /Fe 3 O 4 /WBC composite was explained through FTIR, XPS, charge transfer analyses, and density functional theory calculations (DFT). The deposition of Cr (VI) on the surface of the composite was attributed to electrostatic interaction, redox reactions and complexation between the Fe 2 O 3 /Fe 3 O 4 /WBC composite and Cr (VI) contained in the solution.
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LANGMUIR
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2019
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IF 3.683
Yan Xiong,Jie Chen,Ming Duan,Xiang Li,Jun Li,Can Zhang,Shenwen Fang,Rui Liu,Run Zhang
The investigation of adsorption performance at the adsorbent surface can help to reveal the treatment mechanism and improve the treatment efficiency of adsorption technology for heavy metal ions (HMIs). This work developed a methodology to investigate the adsorption behavior of HMI Cr(VI) at the silica surface by confined near-field evanescent wave (CNFEW) measurement. A silica optical fiber (SOF) was used as the adsorption substrate and light waveguide element to integrate both Cr(VI) adsorption and CNFEW production on its surface. According to the sensitive CNFEW response, the adsorption behavior of Cr(VI) was in situ monitored and real-time evaluated. The thermodynamic information of adsorption equilibrium constant (Kads) and adsorption free energy (ΔG) and dynamic information of the apparent adsorption rate (vads) and adsorption time (tads) were obtained through Langmuir isotherm and kinetic fitting, respectively. Different reaction performances between Cr(VI) and adsorption sites were successfully differentiated, evaluated, and characterized. A site-decided-mechanism was therefore presented to describe the surface interaction process for Cr(VI), which including fast adsorption on type I Si–O– site through electrostatic attraction with and slow adsorption on type II Si–OH site through coordinative interaction with ΔGSiOH–Cr(VI)II = −26.18 kJ mol–1. The adsorption mechanism of Cr(VI) at the SOF silica surface was furthermore verified by zeta potential analysis, Fourier transform infrared investigation, and fluorescence imaging. Unlike conventional ex situ or in bulk detection, the present CNFEW-based approach targets the “localized” adsorption of Cr(VI) adsorbed to the solid adsorbent surface. Consequently, our work favorably constructs a surface platform and provides new insights on understanding the adsorption mechanism for HMIs.
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ADVANCED POWDER TECHNOLOGY
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2019
·
IF 3.25
Osman Ahmed Zelekew,Dong-Hau Kuo,Hairus Abdullah
Herein, we report the bimetallic (Sn,Zn)(O,S) oxysulfide nanocatalyst with a facile method. The Sn-based catalyst with the addition of Zn was synthesized with the proportions of 0, 20, 30 and 50% of Zn to Sn precursors for preparation. The catalysts were characterized by XRD , TEM , SEM XPS , and UV–vis instruments. The nanocatalysts were also tested for the detoxification of Cr +6 . The Sn-20 catalyst with 20 M percent of Zn(Ac) 2 ·2H 2 O showed an excellent performance for the induced photocatalytic reduction of Cr +6 under visible light irradiation at room temperature. The complete reduction of Cr +6 was achieved within 80 min by Sn-20 catalyst. However, 85.6, 97, and 94% of Cr +6 reductions were achieved within 80 min under visible light illumination by Sn-0, Sn-30, and Sn-50 catalysts, respectively. Hence, the bimetallic (Sn,Zn)(O,S) oxysulfide nanocatalyst will be a candidate and highly potential material for the detoxification of Cr(VI)-containing polluted water.
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JOURNAL OF ENVIRONMENTAL MANAGEMENT
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2019
·
IF 4.865
Yuyan Liu,Saran P. Sohi,Siyuan Liu,Junjie Guan,Jingyao Zhou,Jiawei Chen
To address inorganic and organic contaminants in the environment, economic new adsorbents are required. Here we test magnetic biochar for efficient capture of the typical pollutants Cr(VI) and trichloroethylene (TCE) from solution. We used a simple synthesis using 2M FeCl 3 solution and peanut hull biomass to prepare magnetic ZVI biochar at alternate pyrolysis temperatures between 650 and 800 °C. The physicochemical character of the biochars were assessed using X-ray diffraction (XRD) and the Brunauer-Emmett-Teller (BET) method for surface area. The magnetic ZVI biochars were highly effective in the removal of Cr(VI) and TCE. The most effective magnetic biochar produced at 800 °C was further examined using scanning electron microscopy (SEM), revealing a high and even loading of ZVI. After sorption the same magnetic biochar was examined by X-ray photoelectron spectroscopy (XPS) to ascertain the underlying mechanisms. The dependence of Cr(VI) capture on solution pH was also examined. Our interpretation suggests that when pH < pH zpc (2.5) electrostatic attraction and redox reactions dominated the adsorption of Cr(VI). When pH > pH zpc the removal process was controlled mainly by redox reaction and substitution of chromate anions for hydroxyl ( OH) groups. Capture of TCE in contrast involved hydrophobic partitioning, pore-filling and reductive degradation. Overall our results suggest that simple synthesis of magnetic ZVI biochar could offer an economic and effective option to address water contamination issues.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2019
·
IF 14.229
Ranran Yuan,Cailiang Yue,Jinli Qiu,Fuqiang Liu,Aimin Li
TiO 2 @NH 2 -MIL-88B(Fe) heterostructures (TMFe-x) were successfully synthesized and used in an efficient sunlight-driven reduction towards Cr(VI) in a neutral aqueous media. Further, the prepared TMFe-x heterostructures exhibited higher photocatalytic activity when compared with those exhibited by pure TiO 2 and NH 2 -MIL-88B(Fe) under simulated sunlight irradiation. The optical TiO 2 modification content was determined to be 10 wt.% (TMFe-b), with 98.6% Cr(VI) being converted to Cr(III) within 35 min using ammonium oxalate as the hole scavenger at pH = 7. In neutral conditions, the kinetic rate constant (0.0878 min −1 ) was five times larger than the published values. Additionally, the photocatalytic performance of TMFe-b was maintained and Fe leaching was observed to be negligible after the completion of four reaction cycles. The superior photocatalytic property can be attributed to the high photoelectron-hole separation and migration efficiency. Subsequently, TMFe-b achieved Cr(VI) reduction under neutral conditions by capturing hydrogen from the water molecules or the hole scavengers. The photoelectrons and superoxide radicals were the main active species. Furthermore, TMFe-b was able to efficiently eliminate various pollutants through photocatalytic oxidation and reduction. This study suggests a novel strategy for the preparation of environmentally stable and efficient MOF-based photocatalysts to efficiently eliminate various pollutants. Further, there is a huge potential for the practical application of this technology to water purification .
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DALTON TRANSACTIONS
·
2019
·Vol. 48
·期 16
·5384-5396
·
IF 4.052
Xueping Quan,Zhongqiao Sun,Hao Meng,Yide Han,Junbiao Wu,Junli Xu,Yan Xu,Xia Zhang
Developing novel solid adsorbents with high efficiency and excellent selectivity is always an important target in the removal of toxic metal ions from waste water. In this study, a composite nano-adsorbent NH2-mSiO2@MIL-101(Cr) has been fabricated and applied in the efficient removal of Pb(II) and Cr(VI) for the first time. The nanocomposites were characterized by using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), fourier-transform infrared (FT-IR) spectroscopy and thermal gravimetry analysis (TG). The results indicate that a typical core@shell structure has been fabricated by fully coating a mesoporous SiO2 shell over the micro/mesoporous MIL-101(Cr). As a result, the surface charge and the zeta potentials change significantly. Two toxic metal ions, namely, Pb(II) and Cr(VI) were chosen as the main adsorption targets to evaluate the surface adsorption activities. The adsorption conditions were optimized, the influences of other coexisting ions were explored, and the adsorption selectivity was investigated. Interestingly, the NH2-mSiO2@MIL-101(Cr) nanocomposites display a prominent adsorption activity compared with the original MIL-101(Cr) and non-aminated mSiO2@MIL-101(Cr) and excellent selectivity toward Pb(II) in the presence of other divalent metal ions. The adsorption kinetics and adsorption thermodynamics were simulated accordingly, and the enhanced adsorption mechanism was also suggested. The good reusability and adsorption selectivity of the NH2-mSiO2@MIL-101(Cr) suggest their potential applications in the selective removal of special metal ions such as Pb(II) from the waste water.
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危险品化学品经营许可证（带存储）