Multi-walled carbon nanotubes as adsorbents for the removal of parts per billion levels of hexavalent chromium from aqueous solution

被引:200
作者
Pillay, K. [1 ,2 ,3 ]
Cukrowska, E. M. [3 ]
Coville, N. J. [2 ,3 ]
机构
[1] Univ Johannesburg, Dept Chem Technol, ZA-2028 Johannesburg, South Africa
[2] DST NRF Ctr Excellence Strong Mat, Johannesburg, South Africa
[3] Univ Witwatersrand, Sch Chem, Inst Mol Sci, ZA-2050 Johannesburg, South Africa
基金
新加坡国家研究基金会;
关键词
Adsorption; Hexavalent chromium; Multi-walled carbon nanotubes; Langmuir isotherm; Freundlich isotherm; WASTE-WATER; ACTIVATED CARBONS; ASPERGILLUS-NIGER; ADSORPTION; IONS; CR(VI); BIOSORPTION; SLUDGE; WASTEWATERS; REDUCTION;
D O I
10.1016/j.jhazmat.2008.12.011
中图分类号
X [环境科学、安全科学];
学科分类号
08 ; 0830 ;
摘要
The adsorption capabilities for the removal of parts per billion levels (ppb) of hexavalent chromium by three adsorbents namely activated carbon, functionalised multi-walled carbon nanotubes (MWCNTs) and unfunctionalised multi-walled carbon nanotubes were investigated as a function of contact time, initial solution pH, initial Cr(VI) concentrations and the presence of competing anions. The unfunctionalised MWCNTs showed the highest adsorption capability with up to 98% of a 100ppb Cr(VI) solution being adsorbed. Both functionalised and non-functionalised MWCNTs showed a superior adsorption capability to that of activated carbon. The removal of Cr(VI) was higher at lower pH. Furthermore, the uptake of Cr(VI) was hindered by the presence of the competing anions, Cl- and SO42-. Both Langmuir and Freundlich isotherms have been used to describe the Cr(VI) adsorption process. The major mechanisms for Cr(VI) removal have been identified as an ion exchange mechanism, intraparticle diffusion and electrostatic interactions. The adsorbed Cr(VI) could also be desorbed readily from the MWCNTs surface at high pH. (C) 2008 Elsevier B.V. All rights reserved.
引用
收藏
页码:1067 / 1075
页数:9
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