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Indexed by:期刊论文

Date of Publication:2009-08-15

Journal:JOURNAL OF HAZARDOUS MATERIALS

Included Journals:SCIE、EI、PubMed、Scopus

Volume:167

Issue:1-3

Page Number:357-365

ISSN No.:0304-3894

Key Words:Carbon nanotubes; Metal adsorption; Surface properties; Ion exchange

Abstract:Adsorption of nickel, copper, zinc and cadmium from aqueous solutions on carbon nanotubes oxidized with concentrated nitric acid was carried out in single, binary, ternary and quaternary systems. TEM and adsorption of nitrogen were used to determine texture and structural parameters, respectively. The surface chemistry was evaluated using the pH at the point of zero charge, FTIR spectroscopy and XPS analysis. The experimental results showed that all isotherms for Cu(2+)(aq) fit to Langmuir model in each system. On the other hand, the isotherms for Ni(2+)(aq), Cd(2+)(aq) and Zn(2+)(aq) in multi-component systems reveal the effect of competition for adsorption sites seen as a decrease in the amount adsorbed. The uptakes at the equilibrium concentration of 0-0.04 mmol L(-1) in single system and 0-0.15 mmol L(-1) in binary system are in the order Cu(2+)(aq) > Ni(2+)(aq) > Cd(2+)(aq) > Zn(2+)(aq) while for the ternary and quaternary, the order is Cu(2+)(aq) > Cd(2+)(aq) > Zn(2+)(aq) > Ni(2+)(aq). The results indicate that the mechanism of adsorption is governed by the surface features, ion exchange process and electrochemical potential. The latter plays a significant role in multi-component adsorption where redox reactions, not only on the adsorbent surface but also between the adsorbates, are likely to occur. (C) 2009 Elsevier B.V. All rights reserved.