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1.
Chemosphere ; 262: 127832, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32758709

RESUMO

This article has been retracted: please see Elsevier Policy on Article Withdrawal ( https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Authors. The corresponding author informed the journal that there were severe problems with the testing instrument that rendered the subsequent conclusions invalid. The authors apologise for any inconvenience caused.

2.
J Environ Manage ; 263: 110377, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32174524

RESUMO

Because of its superior physical and chemical properties, MnFe2O4 is regarded as one of the best magnetic material alternatives for Fe3O4. However, MnFe2O4 alone cannot remove heavy metal ions and dyes. Here, we report on a new mesoporous magnetic MnFe2O4@CS-SiO2 microsphere material that was synthesised via the hydrothermal method to remove Zn2+ and methylene blue (MB) in simulated textile wastewater. The composite was characterised using a vibrating sample magnetometer, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and a Brunauer-Emmett Teller analysis. The pH, adsorbent dosage, initial adsorbate concentration, and reaction time effects on the removal of Zn2+ and MB were studied under different conditions, and a possible removal mechanism was proposed and discussed. The experimental results show that the suitable pH range for MB adsorption was extremely wide, and the adsorption equilibrium can be reached within 30 min. In addition, the prepared material has excellent stability. With an excellent removal efficiency as high as 56.1% and 93.86% for Zn2+ and MB, respectively, after five consecutive cycles and a superior adsorption capacity compared with other materials, the prepared composite in this paper proved to be a promising and effective magnetic adsorbent for the removal of Zn2+ and MB from textile wastewater.


Assuntos
Azul de Metileno , Poluentes Químicos da Água , Adsorção , Fenômenos Magnéticos , Microesferas , Dióxido de Silício , Zinco
3.
Environ Sci Pollut Res Int ; 27(13): 15337-15349, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32077017

RESUMO

A novel catalyst of Fe-Mn/AC was prepared and used as a heterogeneous catalyst to activate O3/Na2S2O8 for landfill leachate biochemical effluent treatment. The experimental results indicated that the highest COD (84%) and color (98%) removal was obtained at Fe-Mn/AC dosage 1.2 g/L, O3 concentration 1.2 g/L, Na2S2O8 dosage 6 g/L, initial pH 10, and reaction time 100 min. Three-dimensional and excitation emission matrix (3D-EEM) fluorescence spectrometry, Fourier transform infrared spectroscopy (FTIR), and gas chromatography mass spectrometry (GC/MS) of wastewater samples before and after treatment demonstrated that the leachate biochemical effluent contained a large amount of humic and fulvic acid organic compounds. After treatment with this coupling system, both the pollution level of dissolved organic matter (DOM) and the fluorescence intensity declined. The micro morphology of Fe-Mn/AC was characterized using scanning X-ray diffraction patterns (XRD), electron microscope spectra (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. It can be concluded that the microscopic morphology of the catalyst is porous. The main active components are amorphous MnO2 and multivalent iron oxides. Furthermore, the Fe-Mn/AC catalyst showed great reusability; the removal efficiency of COD was only reduced from 84% to 79% at the fourth reaction. Moreover, the COD removal efficiency could recover to 81% after catalyst regeneration.


Assuntos
Águas Residuárias , Poluentes Químicos da Água/análise , Compostos de Manganês , Compostos Orgânicos , Oxirredução , Óxidos
4.
J Environ Manage ; 208: 159-168, 2018 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-29268183

RESUMO

Nano-Fe3O4 was used as heterogeneous catalyst to activate Na2S2O8 for the generation of the sulfate radicals (SO4-) to oxidize the residual pollutants in landfill leachate biochemical effluent. The oxidation performance, wastewater spectral analysis and activator characterization were discussed. Oxidation experimental result shows that nano-Fe3O4 has obvious catalytic effect on Na2S2O8 and can significantly enhance the oxidation efficiencies of Na2S2O8 on landfill leachate biochemical effluent, with COD and color removals above 63% and 95%, respectively. Based on the analyses of three-dimensional excitation emission matrix fluorescence spectrum (3DEEM), ultraviolet-visible spectra (UV-vis), and Fourier Transform infrared spectroscopy (FTIR) of wastewater samples before and after treatment, it can be concluded that the pollution level of dissolved organic matter (DOM) declined and that the humic acid (HA) fractions were efficiently degraded into small molecules of fulvic acid (FA) fractions with less weight and stable structure. Compared to the raw wastewater sample, the aromaticity and substituent groups of the DOM were lessened in the treated wastewater sample. Moreover, the main structure of the organics and functional groups were changed by the Fe3O4/Na2S2O8 system, with substantial decrease of conjugated double bonds. The micro morphology of nano-Fe3O4 was characterized before and after reaction by the methods of scanning electron microscope spectra (SEM), X-ray diffraction pattern (XRD), and X-ray photoelectron spectroscopy (XPS). The XRD pattern analysis showed that nano-Fe3O4 was oxidized into r-Fe2O3 and that the particle size of it also became smaller after reaction. XPS was employed to analyze the content and iron valence on the nano-Fe3O4 surface, and it can be found that the ratio of Fe3+/Fe2+ decreased from 1.8 before reaction to 0.8 after reaction. From the SEM analysis after the treatment, it was determined that the spacing between nano-Fe3O4 was increased, but in turn, the particles decreased in diameter.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Compostos Férricos , Substâncias Húmicas , Oxirredução
5.
Sci Rep ; 6: 21059, 2016 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-26877144

RESUMO

Energy extraction from waste has attracted much interest nowadays. Herein, a coupled redox fuel cell (CRFC) device using heavy metals, such as copper, as an electron acceptor is assembled to testify the recoveries of both electricity and the precious metal without energy consumption. In this study, a NaBH4-Cu(II) CRFC was employed as an example to retrieve copper from a dilute solution with self-electricity production. The properties of the CRFC have been characterized, and the open circuit voltage was 1.65 V with a maximum power density of 7.2 W m(-2) at an initial Cu(2+) concentration of 1,600 mg L(-1) in the catholyte. 99.9% of the 400 mg L(-1) copper was harvested after operation for 24 h, and the product formed on the cathode was identified as elemental copper. The CRFC demonstrated that useful chemicals were recovered and the electricity contained in the chemicals was produced in a self-powered retrieval process.

6.
Bioresour Technol ; 203: 56-61, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-26720140

RESUMO

In order to explore the feasibility of energy-free denitrifying N-rich wastewater, a self-powered device was uniquely assembled, in which ammonia/nitrate coupled redox fuel cell (CRFC) reactor was served as removing nitrogen and harvesting electric energy simultaneously. Ammonia is oxidized at anodic compartment and nitrate is reduced at cathodic compartment spontaneously by electrocatalysis. In 7.14 mM ammonia+0.2M KOH anolyte and 4.29 mM KNO3+0.1M H2SO4 catholyte, the nitrate removal efficiency was 46.9% after 18 h. Meanwhile, a maximum power density of 170 mW m(-2) was achieved when applying Pd/C cathode. When NH4Cl/nitrate and ammonia/nitrite CRFCs were tested, 26.2% N-NH4Cl and 91.4% N-NO2(-) were removed respectively. Nitrogen removal efficiency for real leachate at the same initial NH3-N concentration is 22.9% and nitrification of ammonia in leachate can be used as nitrate source. This work demonstrated a new way for N-rich wastewater remediation with electricity generation.


Assuntos
Fontes de Energia Bioelétrica , Nitrificação , Nitrogênio/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Amônia/química , Reatores Biológicos , Desnitrificação , Eletricidade , Eletrodos , Estudos de Viabilidade , Nitratos/química , Nitritos/química , Óxidos de Nitrogênio , Oxirredução , Águas Residuárias
7.
J Colloid Interface Sci ; 460: 349-60, 2015 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-26385593

RESUMO

The performances of ordered mesoporous carbon CMK-3 (OMC), bamboo-based carbon (BC), and these two kinds of adsorbents modified by thermal treatment in the ammonia atmosphere at high temperatures were evaluated for the removal fluoroquinolone antibiotic (ciprofloxacin) from aqueous solution. The adsorption behavior of ciprofloxacin (CIP) onto OMC and BC including adsorption isotherms and kinetics were investigated. The effect of various factors (pH, ionic strength and temperature) on the adsorption process was also investigated. The results demonstrated that the modified OMC and BC can further enhance the adsorption capacity due to introduce of alkaline nitrogen functionalities on the carbon surface. And their maximum adsorption capacity reached as high as 233.37mgg(-1) and 362.94mgg(-1) under the same experimental conditions, respectively. This is primarily ascribed to the positive effect of the surface basicity. The highest sorption was observed at the lowest solubility, which indicated that hydrophobic interaction was the dominant sorption mechanism for CIP uptake onto the four adsorbents. The adsorption data of antibiotics was analyzed by Langmuir and Freundlich model, and the better correlation was achieved by the Langmuir isotherm. The kinetic data showed that the adsorption of CIP onto OMC and BC follow closely the pseudo-second order model. The removal efficiency and adsorption capacity increased with increasing temperature. The results of thermodynamic study indicated that the adsorption process was a spontaneous and endothermic.

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