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1.
Environ Technol ; 43(10): 1522-1531, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33086947

RESUMO

ABSTRACTThe use of ammonium iron (II) sulphate ((NH4)2Fe(SO4)2) to remediate soil contaminated with Cr (VI) was assessed. (NH4)2Fe(SO4)2 effectively remediated soil contaminated with Cr (VI) and, acted as a fertilizer by supplying nitrogen because it contains ammonium. The effects of the (NH4)2Fe(SO4)2 dose, water content, pH of the soil and the contact time were investigated. The amount of Cr (VI) leached from the most-polluted soil, determined using a leaching toxicity procedure using optimized conditions, was 347.64 mg kg-1 when the soil was untreated and 6.74 mg kg-1 when the soil was treated with (NH4)2Fe(SO4)2. Bio-utilizable Cr contributed 59.44% and 0.16% of the total Cr contents of the untreated and treated soil, respectively. The relatively stable Cr species contributed 24.92% and 98.38% of the total Cr contents of the untreated and treated soil, respectively. The results indicated that adding (NH4)2Fe(SO4)2 markedly decreased the risk of Cr being released from heavily contaminated soil by decreasing the availability of Cr in the soil. Overall, the results indicated that adding (NH4)2Fe(SO4)2 causes some Cr (VI) in contaminated soil to be reduced to Cr (III), and to form a precipitate, which decreases the risk of Cr being released. (NH4)2Fe(SO4)2 can be applied to soil contaminated with Cr (VI) on a large scale because it is cheap and simple to achieve.


Assuntos
Compostos de Amônio , Poluentes do Solo , Cromo/química , Estudos de Viabilidade , Ferro , Solo/química , Poluentes do Solo/química , Sulfatos
2.
Talanta ; 237: 122894, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34736710

RESUMO

In this paper, a facile hydrothermal combined with subsequent two-step post-calcination method was used to fabricate hematite (α-Fe2O3) nanoarrays on fluorine-doped SnO2 glass (FTO). The morphology, crystalline phase, optical property and surface chemical states of the fabricated α-Fe2O3 photoelectrode were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet visible spectroscopy and X-ray photoelectron spectroscopy correspondingly. The α-Fe2O3 photoelectrode exhibits excellent photoelectrochemical (PEC) response toward hydrogen peroxide (H2O2) in aqueous solutions, with a low detection limit of 20 µM (S/N = 3) and wide linear range (0.01-0.09, 0.3-4, and 6-16 mM). Additionally, the α-Fe2O3 photoelectrode shows satisfying reproducibility, stability, selectivity and good feasibility for real samples. Mechanism analysis indicates, comparing with H2O, H2O2 possesses much more fast reaction kinetics over α-Fe2O3 surface, thus the recombination of photogenerated charges are reduced, followed by much more photogenerated electrons are migrated to the counter electrode via external circuit. The insight on the enhanced photocurrent, which is corelative to the concentration of H2O2 in aqueous solution, will stimulate us to further optimize the surface structure of α-Fe2O3 to gain highly efficient α-Fe2O3 based sensors.

3.
J Nanosci Nanotechnol ; 18(1): 62-67, 2018 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-29768812

RESUMO

Gold nanoparticles-supported Cabot Vulcan XC72R (Au/VXC72R) nanocomposite was synthesized by chemical reduction of gold (III) chloride with VXC72R. A novel electrochemical sensor based on the Au/VXC72R nanocomposite has been fabricated for the sensitive detection of rifampicin (RIF). Field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the morphology, structure and compositions of the nanocomposite. Under the optimal conditions, the Au/VXC72R-chitosan/GCE can be used to determine RIF concentration in a linear range from 5 × 10-7 mol/L to 1 × 10-5 mol/L with the detection limit of 1.1 × 107 M (S/N = 3). The proposed approach exhibits good stability, acceptable reproducibility and applicability, which will probably bring widespread applications in quality monitoring in real samples.

4.
Environ Technol ; 36(9-12): 1084-90, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25299348

RESUMO

The removal of hexavalent chromium [Cr(VI)] from aqueous solution by using red mud activated with cetyltrimethylammonium bromide (CTAB) was studied. The optimum operation parameters, such as CTAB concentration, pH values, contact time, and initial Cr(VI) concentration, were investigated. The best concentration of CTAB for modifying red mud was found to be 0.50% (mCTAB/VHCl,0.6 mol/L). The lower pH (<2) was found to be much more favourable for the removal of Cr(VI). Red mud activated with CTAB can greatly improve the removal ratio of Cr(VI) as high as four times than that of original red mud. Adsorption equilibrium was reached within 30 min under the initial Cr(VI) concentration of 100 mg L(-1). The isotherm data were analysed using Langmuir and Freundlich models. The adsorption of Cr(VI) on activated red mud fitted well to the Langmuir isotherm model, and the maximum adsorption capacity was estimated as 22.20 mg g(-1) (Cr/red mud). The adsorption process could be well described using the pseudo-second-order model. The result shows that activated red mud is a promising agent for low-cost water treatment.


Assuntos
Compostos de Cetrimônio/química , Cromo/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Cetrimônio , Concentração de Íons de Hidrogênio , Cinética , Termodinâmica
5.
ACS Appl Mater Interfaces ; 6(23): 20664-9, 2014 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-25382857

RESUMO

Cu2ZnSnSxSe4-x (CZTSSe) counter electrodes (CEs) in dye-sensitized solar cells (DSSCs) are commonly developed with porous structures, but their high surface area could also retard electron transport processes owing to the abundant grain boundaries. Herein, we employed a convenient solution method and a rapid heating process to prepare well crystalline CZTSSe CEs in DSSCs. The influence of crystallization of CZTSSe film on DSSCs performances was discussed in depth. The thermogravimetric analysis, phase morphology, conductivity, and electrochemical characteristics of CZTSSe films were performed. It is found that the rapid heating process is beneficial to the formation of well crystalline film with large grains. As the porosity and grain boundaries in the bulk film are dramatically reduced with the enhanced crystallization, the charge transport process is gradually improved. Using cyclic voltammogram and electrochemical impedance spectroscopy measurements, we propose that the accelerating charge transport is of great importance to the photovoltaic performances of DSSCs due to their superior electrocatalytic activities. As the highest cell efficiency was achieved, well crystalline CZTSSe is an efficient CE catalytic material.

6.
Chem Commun (Camb) ; 50(84): 12726-9, 2014 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-25205452

RESUMO

CZTS exhibited apparently phase-dependent photocatalytic H2 evolution under visible light. Possible factors for the phase-dependent photocatalytic activity of CZTS were discussed in detail.

7.
J Biomed Nanotechnol ; 5(5): 602-6, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-20201439

RESUMO

A spectrofluorimetric method was established for the quantitative determination of 3-glycidoxypropyltrimethoxysilane (GPTMS), based on the quantitative reaction between dihydroxyl of hydrated epoxy groups and potassium periodate generating formaldehyde and the reaction of the formaldehyde with acetylacetone in the presence of ammonium ions generating a new compound having yellow green fluorescence. The established method was then used to determine the purity of a commercially obtained GPTMS sample and the amount of epoxy groups on GPTMS doped nanosilica composite (GPTMS/nano-SiO2). The conditions such as the concentrations of ammonium salts and acetylacetone, pH value, coloring temperature, and coloring time were investigated in detail with respect to their effects on the fluorescence intensity. It was found that the established method is simple in terms of operation and can be used to practically determine the purity of GPTMS and the amount of epoxy groups on GPTMS/nano-SiO2 with good accuracy and reproducibility.


Assuntos
Nanoestruturas/química , Nanoestruturas/ultraestrutura , Silanos/química , Dióxido de Silício/química , Espectrometria de Fluorescência/métodos , Cristalização/métodos , Substâncias Macromoleculares/química , Teste de Materiais/métodos , Conformação Molecular , Tamanho da Partícula , Propriedades de Superfície
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