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Adsorption of Cu(II) on oxidized multi-walled carbon nanotubes in the presence of hydroxylated and carboxylated fullerenes.

Wang J, Li Z, Li S, Qi W, Liu P, Liu F, Ye Y, Wu L, Wang L, Wu W - PLoS ONE (2013)

Bottom Line: The effect of C60(OH)n on Cu(II) adsorption of oMWCNTs was not significant at low C60(OH)n concentration, whereas a negative effect was observed at higher concentration.The adsorption of Cu(II) on oMWCNTs was enhanced with increasing pH values at pH < 5, but decreased at pH ≥ 5.The double sorption site model was applied to simulate the adsorption isotherms of Cu(II) in the presence of C60(OH)n and fitted the experimental data well.

View Article: PubMed Central - PubMed

Affiliation: Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, PR China.

ABSTRACT
The adsorption of Cu(II) on oxidized multi-walled carbon nanotubes (oMWCNTs) as a function of contact time, pH, ionic strength, temperature, and hydroxylated fullerene (C60(OH)n) and carboxylated fullerene (C60(C(COOH)2)n) were studied under ambient conditions using batch techniques. The results showed that the adsorption of Cu(II) had rapidly reached equilibrium and the kinetic process was well described by a pseudo-second-order rate model. Cu(II) adsorption on oMWCNTs was dependent on pH but independent of ionic strength. Compared with the Freundlich model, the Langmuir model was more suitable for analyzing the adsorption isotherms. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Cu(II) adsorption on oMWCNTs was spontaneous and endothermic. The effect of C60(OH)n on Cu(II) adsorption of oMWCNTs was not significant at low C60(OH)n concentration, whereas a negative effect was observed at higher concentration. The adsorption of Cu(II) on oMWCNTs was enhanced with increasing pH values at pH < 5, but decreased at pH ≥ 5. The presence of C60(C(COOH)2)n inhibited the adsorption of Cu(II) onto oMWCNTs at pH 4-6. The double sorption site model was applied to simulate the adsorption isotherms of Cu(II) in the presence of C60(OH)n and fitted the experimental data well.

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Effect of Cu(II) initial concentrations on Cu(II) adsorption onto oMWCNTs as a function of C60(OH)n initial concentrations, m/V  = 0.5 g/L, pH = 7.00±0.10, I = 0.01 mol/L NaCl, T = 25±1°C.
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pone-0072475-g010: Effect of Cu(II) initial concentrations on Cu(II) adsorption onto oMWCNTs as a function of C60(OH)n initial concentrations, m/V  = 0.5 g/L, pH = 7.00±0.10, I = 0.01 mol/L NaCl, T = 25±1°C.

Mentions: To further investigate the adsorption process of C60(OH)n and Cu(II) onto oMWCNTs, the adsorption of Cu(II) onto oMWCNTs as a function of: 1) the initial concentration of C60(OH)n at different ratios of solid to liquid; and 2) the initial concentrations of Cu(II), are shown in Figure 10 and Figure 11. As can be seen from Figure 10 and 11, C60(OH)n has almost no influence on Cu(II) adsorption at low concentration. Whereas, it starts to inhibit the adsorption ability of oMWCNTs for Cu(II) when the concentration of C60(OH)n is higher than 50 mg/L. Figure 10 shows that when the initial concentration of Cu(II) is 1.87×10−4 mol/L, its adsorption percentage on the oMWCNTs decreases from about 94% to about 45%; the Cu(II) adsorption decreases from ∼93% to 27% at 9.44×10−5 mol/L. When the initial Cu(II) concentration becomes 3.31×10−5 mol/L, the adsorption percentage drops from 91% to 3%. In other words, the Cu(II) adsorption percentage decreases regularly as the initial concentration of Cu(II) is reduced. This also shows that the Cu (II) is only adsorbed on oMWCNT surfaces, and has no interaction with C60(OH)n. Figure 11 illustrates that when the dosage of oMWCNTs are 0.25 g/L and 0.1 g/L and the concentration of C60(OH)n is less than 100 mg/L, the adsorption of Cu(II) on oMWCNTs falls sharply. The reduction of Cu(II) adsorption becomes mild when the concentration of C60(OH)n is higher than 100 mg/L. This indicates that the low concentration of oMWCNTs does not offer enough available sites for the adsorption of C60(OH)n, but with the increasing dosage of oMWCNTs, the available adsorption sites on oMWCNTs surfaces gradually increase, leading to more and more C60(OH)n adsorption. Consequently, adsorption of Cu(II)on oMWCNTs decreases sharply.


Adsorption of Cu(II) on oxidized multi-walled carbon nanotubes in the presence of hydroxylated and carboxylated fullerenes.

Wang J, Li Z, Li S, Qi W, Liu P, Liu F, Ye Y, Wu L, Wang L, Wu W - PLoS ONE (2013)

Effect of Cu(II) initial concentrations on Cu(II) adsorption onto oMWCNTs as a function of C60(OH)n initial concentrations, m/V  = 0.5 g/L, pH = 7.00±0.10, I = 0.01 mol/L NaCl, T = 25±1°C.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3756995&req=5

pone-0072475-g010: Effect of Cu(II) initial concentrations on Cu(II) adsorption onto oMWCNTs as a function of C60(OH)n initial concentrations, m/V  = 0.5 g/L, pH = 7.00±0.10, I = 0.01 mol/L NaCl, T = 25±1°C.
Mentions: To further investigate the adsorption process of C60(OH)n and Cu(II) onto oMWCNTs, the adsorption of Cu(II) onto oMWCNTs as a function of: 1) the initial concentration of C60(OH)n at different ratios of solid to liquid; and 2) the initial concentrations of Cu(II), are shown in Figure 10 and Figure 11. As can be seen from Figure 10 and 11, C60(OH)n has almost no influence on Cu(II) adsorption at low concentration. Whereas, it starts to inhibit the adsorption ability of oMWCNTs for Cu(II) when the concentration of C60(OH)n is higher than 50 mg/L. Figure 10 shows that when the initial concentration of Cu(II) is 1.87×10−4 mol/L, its adsorption percentage on the oMWCNTs decreases from about 94% to about 45%; the Cu(II) adsorption decreases from ∼93% to 27% at 9.44×10−5 mol/L. When the initial Cu(II) concentration becomes 3.31×10−5 mol/L, the adsorption percentage drops from 91% to 3%. In other words, the Cu(II) adsorption percentage decreases regularly as the initial concentration of Cu(II) is reduced. This also shows that the Cu (II) is only adsorbed on oMWCNT surfaces, and has no interaction with C60(OH)n. Figure 11 illustrates that when the dosage of oMWCNTs are 0.25 g/L and 0.1 g/L and the concentration of C60(OH)n is less than 100 mg/L, the adsorption of Cu(II) on oMWCNTs falls sharply. The reduction of Cu(II) adsorption becomes mild when the concentration of C60(OH)n is higher than 100 mg/L. This indicates that the low concentration of oMWCNTs does not offer enough available sites for the adsorption of C60(OH)n, but with the increasing dosage of oMWCNTs, the available adsorption sites on oMWCNTs surfaces gradually increase, leading to more and more C60(OH)n adsorption. Consequently, adsorption of Cu(II)on oMWCNTs decreases sharply.

Bottom Line: The effect of C60(OH)n on Cu(II) adsorption of oMWCNTs was not significant at low C60(OH)n concentration, whereas a negative effect was observed at higher concentration.The adsorption of Cu(II) on oMWCNTs was enhanced with increasing pH values at pH < 5, but decreased at pH ≥ 5.The double sorption site model was applied to simulate the adsorption isotherms of Cu(II) in the presence of C60(OH)n and fitted the experimental data well.

View Article: PubMed Central - PubMed

Affiliation: Radiochemistry Laboratory, School of Nuclear Science and Technology, Lanzhou University, Lanzhou, PR China.

ABSTRACT
The adsorption of Cu(II) on oxidized multi-walled carbon nanotubes (oMWCNTs) as a function of contact time, pH, ionic strength, temperature, and hydroxylated fullerene (C60(OH)n) and carboxylated fullerene (C60(C(COOH)2)n) were studied under ambient conditions using batch techniques. The results showed that the adsorption of Cu(II) had rapidly reached equilibrium and the kinetic process was well described by a pseudo-second-order rate model. Cu(II) adsorption on oMWCNTs was dependent on pH but independent of ionic strength. Compared with the Freundlich model, the Langmuir model was more suitable for analyzing the adsorption isotherms. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that Cu(II) adsorption on oMWCNTs was spontaneous and endothermic. The effect of C60(OH)n on Cu(II) adsorption of oMWCNTs was not significant at low C60(OH)n concentration, whereas a negative effect was observed at higher concentration. The adsorption of Cu(II) on oMWCNTs was enhanced with increasing pH values at pH < 5, but decreased at pH ≥ 5. The presence of C60(C(COOH)2)n inhibited the adsorption of Cu(II) onto oMWCNTs at pH 4-6. The double sorption site model was applied to simulate the adsorption isotherms of Cu(II) in the presence of C60(OH)n and fitted the experimental data well.

Show MeSH
Related in: MedlinePlus