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Huang J.,Anhui Agricultural University | Wu Z.,Anhui Environmental Monitoring Center | Chen L.,Qinghai University | Sun Y.,CAS Hefei Institutes of Physical Science
Journal of Molecular Liquids | Year: 2015

Graphene oxides (GOs) were synthesized by modified Hummers method and were characterized by scanning electron microscopy, Fourier transform infrared spectra, X-ray photoelectron spectra and Raman spectra. The characteristic results indicated that GOs presented a variety of oxygen-containing functional groups. Effect of solution chemistry (i.e., contact time, pH, ionic strength, temperature and initial concentration) on the adsorption of Cd(II) onto GOs was investigated by batch techniques. The adsorption of Cd(II) on GOs significantly increased with increasing pH from 4.0 to 6.0, and then high-level adsorption was observed at pH > 6.0. The adsorption of Cd(II) on GOs was independent of ionic strength over a wide range of pH, indicating that inner-sphere surface complexation dominated the Cd(II) adsorption. The maximum adsorption capacity of Cd(II) on GOs calculated from Langmuir model at pH 3.5 and 293 K was 111.11 mg/g. The thermodynamic parameters calculated from temperature-dependent isotherms indicated that the adsorption of Cd(II) on GOs was an exothermal and spontaneous processes. The result from surface complexation modeling indicated that the pH-edge adsorption of Cd(II) on GOs can be fitted by ionic exchange and surface complexation sites very well. The results indicated that the GOs can potentially be served as a promising adsorbent for the immobilization of heavy metals in environmental cleanup due to its high adsorption capacity. © 2015 Elsevier B.V. All rights reserved. Source


Xia S.,Zhejiang Normal University | Yu M.,Zhejiang Normal University | Hu J.,Zhejiang Normal University | Feng J.,Zhejiang Normal University | And 3 more authors.
Electrochemistry Communications | Year: 2014

Co3O4 spheres and cubes have been prepared for the electrochemical determination of hydrogen peroxide. The Co3O 4 cube/nafion electrode has shown better sensitivity and lower detection limit than that of Co3O4 sphere electrode. The models of the interface of Co3O4 and glass carbon electrode were presented and the mechanism of interface-related enhancement was investigated. © 2013 Elsevier B.V. Source


Huang J.,Anhui Agricultural University | Wu Z.,Anhui Environmental Monitoring Center | Chen L.,Qinghai University | Sun Y.,CAS Hefei Institutes of Physical Science
Journal of Molecular Liquids | Year: 2015

Abstract The sorption of Cd(II) and U(VI) on sepiolite as a function of contact time, pH, ionic strength, temperature and initial concentration was investigated by batch techniques. The sorption kinetics showed that sorption of Cd(II) and U(VI) on sepiolite can be satisfactorily fitted by pseudo-second order kinetic model with high correlation coefficients of 0.999. The sorption of Cd(II) and U(VI) on sepiolite significantly decreased with increasing ionic strength at pH < 4.0, whereas the sorption of Cd(II) and U(VI) on sepiolite was independent of ionic strength at pH > 5.0, indicating that cation exchange/outer sphere surface complexation and inner-sphere surface complexation dominated the Cd(II) and U(VI) sorption on sepiolite at pH < 4.0 and pH > 5.0, respectively. According to surface complexation modeling, the sorption of Cd(II) and U(VI) on sepiolite can be satisfactorily simulated by diffuse double layer model with cation exchange sites (XNa/XH) at low pH and surface complexation sites (SOCd+/SOUO2+) at high pH conditions. The finding presented herein indicated that clay minerals can potentially be served as an efficient retardant for the immobilization of heavy metals and radionuclides in environmental cleanup. © 2015 Elsevier B.V. Source


Zhang F.,Hohai University | Zhang F.,Anhui Environmental Monitoring Center | Lu G.,Hohai University | Liu J.,Hohai University | And 2 more authors.
Ecotoxicology and Environmental Safety | Year: 2014

Polybrominated diphenyl ethers (PBDEs) are of great environmental concern due to bioaccumulation and biomagnification in different food chains. However, significant biotransformation of some congeners via reductive debromination has been observed during in vivo and in vitro laboratory exposures. Little is known about the fate of 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153) in fish. In the present study, crucian carp ( Carassius auratus) were exposed to BDE-153 at a concentration of 10. μg/g in food for 28 days. BDE-153 and its metabolites in different tissues were identified and quantified using gas chromatography coupled with tandem mass spectrometry and ultra-high performance liquid chromatography coupled with tandem mass spectrometry. In addition to eight debrominated metabolites, four oxidative metabolites were detected 4'-hydroxy-2,2',4,5'-tetra-BDE, 6-hydroxy-2,2',4,4'-tetra-BDE, 2,4-dibromophenol and 2,4,6-tribromophenol. With regard to the concentrations of BDE-153 and the major metabolites, the contribution order of different tissues was bile>brain>liver>gill>muscle. The highest concentrations of BDE-153 and metabolite 2,2',4,4'-tetrabromodiphenyl ether were detected in bile at 808. ng/g and 157. ng/g, respectively. Our results suggested that three possible metabolic pathways of BDE-153 occurred in crucian carp via dietary exposure: debromination, hydroxylation and cleavage of the diphenyl ether bond. These findings indicated evidence of the bioavailability of BDE-153 from food in the form of debrominated metabolites and oxidative metabolites in freshwater fish, which is critical to understanding the complete risks associated with PBDE bioaccumulation and metabolism in humans and wildlife. © 2014. Source

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