Adsorption of Humic Acid by Multi-Walled Carbon Nanotubes from Boiler Feedwater
The multi-walled carbon nanotubes (MCNTs) are used as an adsorbent to remove humic acid (HA) from boiler feedwater. The experiment carries on in different temperatures, different MCNTs dosages, different pH value and different HA initial concentration to study adsorption HA property by MCNTs. The adsorption kinetics is well fitted with pseudo-second-order rate model, the adsorption mechanism is mainly attributed to the π-π electron-donor-acceptor interaction between the aromatic ring of HA and the surface carboxylic groups of MCNTs. The adsorption isotherms are fitted better with Langmuir than Freundlich models, the parameters of equilibrium constant, standard free energy (ΔG), standard enthalpy (ΔH), and standard entropy changes (ΔS) are calculated according to experiments, which shows adsorption of HA onto PAC is an exothermic process.
Zhenyu Du and X.B Sun
Z. P. Zhu et al., "Adsorption of Humic Acid by Multi-Walled Carbon Nanotubes from Boiler Feedwater", Advanced Materials Research, Vols. 113-116, pp. 1088-1091, 2010