Limits...
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.

Show MeSH

Related in: MedlinePlus

Raman spectra of oMWCNTs before and after C60(OH)n/C60(C(COOH)2)n adsorption.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3756995&req=5

pone-0072475-g004: Raman spectra of oMWCNTs before and after C60(OH)n/C60(C(COOH)2)n adsorption.

Mentions: Raman spectroscopy of oMWCNTs presents in Figure 4 are composed of two characteristic peaks. The peak near 1350 cm−1 is the D-band corresponding to the disordered sp2-hybridized carbon atoms of nanotubes while the peak near 1580 cm−1 is the G-band corresponding to the structural integrity of sp2-hybridized carbon atoms of nanotubes [19]. As can be observed, the G-band of oMWCNTs shows an increase after C60(OH)n adsorption. The G band is due to the bond stretching of both aromatic and aliphatic C−C pairs [36]–[38]. This suggests that oMWCNTs exit more crystalline graphitic structures after the adsorption C60(OH)n. Figure S3 and Figure S4 in File S1 plot the zeta potential of oMWCNTs. All of zeta potentials of oMWCNTs become more negative as the concentration of C60(OH)n/C60(C(COOH)2)n increased. Meanwhile the change of oMWCNTs zeta potential with increasing of C60(OH)n concentration is more regular than that with increasing of C60(C(COOH)2)n concentration. This demonstrates that the zeta potential of oMWCNTs have been changed by C60(OH)n adsorbed. Figure S5 in File S1 shows photographs of oMWCNTs and C60(OH)n/C60(C(COOH)2)n solutions after centrifugation. The solid and liquid phases are separated by using centrifugation for samples “A” to “G”. Interestingly, it is noticed that somewhat better dispersion is achieved for sample “G”, which is consistent with the analysis of the oMWCNTs zeta potential (seen in Figure S3 and Figure S4 in File S1). Therefore, it is clear that the presence of C60(OH)n can promotes oMWCNTs dispersion in adsorption system.


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)

Raman spectra of oMWCNTs before and after C60(OH)n/C60(C(COOH)2)n adsorption.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0072475-g004: Raman spectra of oMWCNTs before and after C60(OH)n/C60(C(COOH)2)n adsorption.
Mentions: Raman spectroscopy of oMWCNTs presents in Figure 4 are composed of two characteristic peaks. The peak near 1350 cm−1 is the D-band corresponding to the disordered sp2-hybridized carbon atoms of nanotubes while the peak near 1580 cm−1 is the G-band corresponding to the structural integrity of sp2-hybridized carbon atoms of nanotubes [19]. As can be observed, the G-band of oMWCNTs shows an increase after C60(OH)n adsorption. The G band is due to the bond stretching of both aromatic and aliphatic C−C pairs [36]–[38]. This suggests that oMWCNTs exit more crystalline graphitic structures after the adsorption C60(OH)n. Figure S3 and Figure S4 in File S1 plot the zeta potential of oMWCNTs. All of zeta potentials of oMWCNTs become more negative as the concentration of C60(OH)n/C60(C(COOH)2)n increased. Meanwhile the change of oMWCNTs zeta potential with increasing of C60(OH)n concentration is more regular than that with increasing of C60(C(COOH)2)n concentration. This demonstrates that the zeta potential of oMWCNTs have been changed by C60(OH)n adsorbed. Figure S5 in File S1 shows photographs of oMWCNTs and C60(OH)n/C60(C(COOH)2)n solutions after centrifugation. The solid and liquid phases are separated by using centrifugation for samples “A” to “G”. Interestingly, it is noticed that somewhat better dispersion is achieved for sample “G”, which is consistent with the analysis of the oMWCNTs zeta potential (seen in Figure S3 and Figure S4 in File S1). Therefore, it is clear that the presence of C60(OH)n can promotes oMWCNTs dispersion in adsorption system.

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