| Title | Comparison kinetics studies of Cu(II) adsorption by multi-walled carbon nanotubes in homo and heterogeneous systems: Effect of nano-SiO2 |
| Authors | Sun, Wei-Ling Xia, Jing Shan, Ying-Chun |
| Affiliation | Peking Univ, Dept Environm Engn, Minist Educ, Key Lab Water & Sediment Sci, Beijing 100871, Peoples R China. |
| Keywords | Adsorption kinetics Cu(II) Multi-walled carbon nanotubes Nano-SiO2 NATURAL ORGANIC-MATTER SWCNT-COOH SURFACES DIVALENT METAL-IONS SPHAGNUM MOSS PEAT AQUEOUS-SOLUTION FULVIC-ACID REMOVAL PB(II) COPPER(II) SORPTION |
| Issue Date | 2014 |
| Publisher | chemical engineering journal |
| Citation | CHEMICAL ENGINEERING JOURNAL.2014,250,119-127. |
| Abstract | The adsorption kinetics of Cu(II) in homogeneous systems of CNTs and heterogeneous systems of CNTs and nano-SiO2 were investigated using ion selective electrode potentiometry. Particular attention was paid on the role of nano-SiO2 in the adsorption kinetics of Cu(II) by CNTs. It was found that the Cu(II) adsorption by CNTs and CNTs-SiO2 mixture was well described by pseudo-second-order kinetics. In homogeneous systems, the equilibrium time of Cu(II) adsorption decreases and the pseudo-second-order rate constant (k(2)) increases with increasing CNTs concentrations. Comparing the different types of CNTs, hydroxy CNTs (CNTs-OH), with higher k(2) values, adsorb Cu(II) ion much faster than carboxyl CNTs (CNTs-COOH). This may be ascribed to their different adsorption mechanisms. The electrostatic attraction is the primary mechanism of Cu(II) adsorption by CNTs-OH, while Cu(II) adsorbed on CNT-COOH through complexing with the carboxyl groups on the surface of CNTs besides electrostatic attraction. In heterogeneous systems of CNTs and nano-SiO2, the Cu(II) adsorption reaches equilibrium much faster than in homogeneous systems of CNTs, indicating nano-SiO2 accelerates the Cu(II) adsorption. This acceleration effect is possibly related to the adsorption mechanism (electrostatic attraction) and higher BET surface area of nano-SiO2. FTIR and XPS spectra demonstrate the binding of nano-SiO2 and CNTs, and CNTs and Cu(II). The present results highlight the significant influence of nano-SiO2 on the Cu(II) adsorption by CNTs. Hence, it is critical to consider these effects in modeling and predicting the adsorption kinetics of metals by CNTs in heterogeneous systems. (C) 2014 Elsevier B.V. All rights reserved. |
| URI | http://hdl.handle.net/20.500.11897/158245 |
| ISSN | 1385-8947 |
| DOI | 10.1016/j.cej.2014.03.094 |
| Indexed | SCI(E) EI |
| Appears in Collections: | 环境科学与工程学院 水沙科学教育部重点实验室（联合） |
