| 1. |
- Zou, Yidong, et al.
(författare)
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beta-Cyclodextrin modified graphitic carbon nitride for the removal of pollutants from aqueous solution : experimental and theoretical calculation study
- 2016
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Ingår i: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 4:37, s. 14170-14179
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Tidskriftsartikel (refereegranskat)abstract
- A novel beta-cyclodextrin modified, multifunctional, layer-by-layer graphitic carbon nitride (g-C3N4/beta-CD) was successfully synthesized and applied as an effective adsorbent for the removal of methyl orange (MO) and Pb(II) from aqueous solutions under various environmental conditions (e.g., solution pH, solid content, contact time and temperature). The kinetic results indicated that the adsorption was dominated by chemisorption, and the higher adsorption capacity of g-C3N4/beta-CD was attributed to it having more oxygen-containing functional groups than g-C3N4. The Langmuir, Freundlich and Sips models were applied to simulate the adsorption isotherms of MO and Pb(II), and the results demonstrated that the adsorption of MO was attributed to multilayer adsorption, while the coverage adsorption of Pb(II) on the g-C3N4/beta-CD was monolayer adsorption. The thermodynamic parameters showed that the adsorption of both MO and Pb(II) was spontaneous and endothermic. The DFT calculations further evidenced the surface complexation and electrostatic interaction of Pb(II) on the g-C3N4 and g-C3N4/beta-CD, whereas, the interaction of MO with g-C3N4 and g-C3N4/beta-CD was mainly attributed to hydrogen bonds and strong pi-pi interactions. The results demonstrated that g-C3N4/beta-CD is a promising material for the efficient removal of organic and inorganic pollutants in environmental pollution remediation.
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| 2. |
- Yu, Shujun, et al.
(författare)
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Spectroscopic and theoretical studies on the counterion effect of Cu(II) ion and graphene oxide interaction with titanium dioxide
- 2016
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Ingår i: ENVIRONMENTAL SCIENCE-NANO. - : Royal Society of Chemistry. - 2051-8153 .- 2051-8161. ; 3:6, s. 1361-1368
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Tidskriftsartikel (refereegranskat)abstract
- With the widespread use of graphene oxide (GO), it is inevitable that part of GO is released into the environment and co-exist with heavy metal ions as contaminants and is likely to be co-adsorbed on minerals and oxides. This study, for the first time, demonstrates the individual and mutual removal mechanism of GO and Cu(II) on titanium dioxide (TiO2) by batch experiments, spectroscopic analysis and density functional theory (DFT) computations. Electrostatic interaction and hydrogen bonding are the dominant modes of GO sorption onto TiO2, and the interaction of Cu(II) with TiO2 is mainly dominated by inner-sphere surface complexation. The presence of Cu(II) enhances GO coagulation on TiO2 and vice versa. The experimental results are further verified by DFT sorption energy (Es) calculations in the order (TiO2-GO)-Cu > TiO2-GO for GO interaction and (TiO2-GO)-Cu > TiO2-Cu for Cu(II) interaction. The mutual interaction is favorable for the simultaneous removal of GO and heavy metal ions by surface complexation between Cu(II) and oxygen-containing functional groups. These findings might facilitate better understanding of the co-removal behavior of carbon nanomaterials and heavy metal ions on oxides, which is crucial to decreasing the environmental toxicity of pollutants in the natural environment.
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| 3. |
- Zou, Yidong, et al.
(författare)
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Coagulation Behavior of Graphene Oxide on Nanocrystallined Mg/AI Layered Double Hydroxides : Batch Experimental and Theoretical Calculation Study
- 2016
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 50:7, s. 3658-3667
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Tidskriftsartikel (refereegranskat)abstract
- Graphene oxide (GO) has attracted considerable attention because of its remarkable enhanced adsorption and multifunctional properties. However, the toxic properties of GO nanosheets released into the environment could lead to the instability of biological system. In aqueous phase, GO may interact with fine mineral particles, such as chloridion intercalated nanocrystallined Mg/Al layered double hydroxides (LDH-Cl) and nanocrystallined Mg/Al LDHs (LDH CO3), which are considered as coagulant molecules for the coagulation and removal of GO from aqueous solutions. Herein the coagulation of GO on LDHs were studied as a function of solution pH, ionic strength, contact time, temperature and coagulant concentration. The presence of LDH Cl and LDH-CO3 improved the coagulation of GO in solution efficiently, which was mainly attributed to the surface oxygen-containing functional groups of LDH Cl and LDH-CO3 occupying the binding sites of GO. The coagulation of GO by LDH-CI and LDH-CO3 was strongly dependent on pH and ionic strength. Results of coagulation of GO on LDHs was energetically favored by electrostatic interactions and hydrogen bonds, which was further evidenced by FTIR and XPS analysis. By integrating the experimental results, it was clear that LDH Cl could be potentially used as a cost-effective coagulant for the elimination of GO from aqueous solutions, which could efficiently decrease the potential toxicity of GO in the natural environment.
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