Characterization of Single-Walled Carbon Nanotubes and Adsorption of Perchlorate in Water
2015
Xu, Yongsen | Lou, Jie-Chung | Chou, Ming-Shean | Hsu, Kai-Lin | Han, Jia-Yun
The current study focuses on the removal of perchlorate in water using single-walled carbon nanotubes (SWCNTs) and granular ferric hydroxide as sorbents. The randomly distributed tubes were observed by scanning electron microscopy. The influence of temperature and content of natural humic acid on the perchlorate adsorption capacity was examined at pH 3. The adsorption data were fitted with three models: modified Freundlich, pseudo-first order, and pseudo-second order. The modified Freundlich model produced the best fit to describe the kinetic adsorption processes. The adsorption capacities of perchlorate measured at 25 °C and pH 3 using single-walled carbon nanotubes and granular ferric hydroxide were about 6 and 3 mg/g, respectively. The influence of natural humic acid on perchlorate adsorption by SWCNTs was examined. Natural humic acid was derived from raw water in Gao-Ping River in south Taiwan. Lower adsorption reaction rates of perchlorate were obtained at higher humic acid concentrations. High humic acid concentrations induce the compression of the electric double layer that consequently reduces the surface potential energy and electrostatic repulsion.
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