Study on Kinetics, Thermodynamics and Mechanism for Carbon Nanotubes Adsorbing Humic Acid

doi:10.3724/SP.J.1077.2011.00170

Abstract

Abstract: The dissolved organic carbon in natural water was mainly from soluble humicacid(HA) which had much harms in industrial and drinkablewater. As a new adsorbent, the multi-walled carbon nanotubes (MCNTs) were used toremove HA at different pH value, different MCNTs dosages and different HA initialconcentration, a series of experiments including batch adsorption, adsorptionisotherm were carried. The adsorption kinetics data was fittedwith pseudo-second-order rate model, their linear correlations was above 0.99,and equilibrium adsorptioncapacity obtained from fitting curve was 27mg/g, consistent with theexperimental results (25.5mg/g). The adsorption isotherm test was carried at 25℃-50℃, the equilibrium adsorptioncapacity was 29.7mg/g by Langmuir model, which was similar to theexperiment results. The free energy (Δ<>G), enthalpy(Δ<>H) and entropy(Δ<>S) were obtanined with Clapeyron-Clausius and Gibbs-Helmholtz equationin the adsorption isotherm, which all were negative, indicated that HA adsorbedby MCNT was an exothermic process of entropy reduction. MCNT’s outer surfaces,layer interspace,inner cavity and aggregated pores became efficient adsorption space for HA. Theπ-π interactionsbetween HA and MCNT played an important role in the adsorption process.

Key words: multi-walled carbon nanotubes (MCNT), humic acid (HA), adsorption, kinetics, thermodynamics

CLC Number:

TQ174

ZHU Zhi-PING, HUANG Ke-Long, ZHOUYi. Study on Kinetics, Thermodynamics and Mechanism for Carbon Nanotubes Adsorbing Humic Acid[J]. Journal of Inorganic Materials, 2011, 26(2): 170-174.

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