Adsorption and Removal of Sudan I, II from Organic Solutions by Oxidized Multiwalled Carbon Nanotubes
Sudan dyes are toxic or carcinogenic even at low concentrations, which are illegally used as additives in food products to
maintain their red color and thus stimulate sales of these products in the market recently. A facile adsorption procedure for the removal of
Sudan I and II in n-hexane using oxidized multi-walled carbon nanotubes (O-MWCNTs) is presented in this paper. The effect of absorption
conditions including absorption time, amount of adsorbent, initial concentration of Sudan I and II was examined. Two isotherm
models were used to describe the adsorption equilibrium, while three kinetic models were applied to evaluate the adsorption process. The
adsorption process and equilibrium for Sudan I and II were all proved to be fitted by the Langmuir model and second-order kinetic
model. The O-MWCNTs possessed fast kinetics for Sudan I and II from n-hexane solvent with each saturation time of <30 min, and correspondingly
the maximum adsorption capacities for Sudan I and II were 41.408 mg/g and 47.037 mg/g, respectively.
Keywords: Sudan dyes, adsorption, oxidized multi-walled carbon nanotubes, isotherms, kinetics.
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