Efficiency of multi-walled carbon nanotubes for removal of 2-naphthol orange dye from aqueous solutions

  Background: Carbon nanotubes have been considered as dye adsorbent. The colored wastewater must be treated to reduce the environmental risks .   Objective : The aim of this study was to determine the efficiency of multi-walled carbon nanotubes for removal of 2-naphthol orange dye from aqueous solutions.   Methods: This experimental study was conducted at school of public health affiliated to Yazd University of medical sciences during 2012 . The effects of different parameters including detention time , PH value, mixing intensity, the initial concentration of dye, and carbon nanotubes dosage were studied for removal of dye. All experiments were repeated twice and then adsorption isotherms and kinetics of different models were analyzed by comparing the coefficient of determination .   Findings: The maximum dye adsorption occurred during the first 30 minutes. The sorption capacity for adsorption of the dye was found to be 2.76 mg/gr. The dye removal efficiency was increased from 87% to 97.2% by decreasing the initial concentration of dye from 100 to 25 mg/l. By increasing the adsorbent dose from 0.05 to 0.4 g/l, the dye removal efficiency was increased from 70.7% to 94.8%. The general order kinetic model provided the best fit to the pseudo-second order kinetic adsorption model and the equilibrium data were best fitted to the Freundlich isotherm model. The maximum efficiency was found to be 97.2%.   Conclusion: Multi-walled carbon nanotubes can be effective for removal of 2-naphthol orange dye.