Efficiency of Multi Walled Carbon Nanotubes for Removing Direct Blue 71 from Aqueous Solutions

Abstract

Dye wastewater produced from industrial activity is usually toxic, resistant to
biodegradation and persistent in the environment. The aim of this study was to
evaluate the efficiency of multiwalled carbon nanotubes (MWCNTs) for decolorization
of Direct Blue 71 (DB71). In this experimental study, the effect of various variables
including contact time, solution pH, adsorbent dose, and initial dye concentration was
evaluated in a batch reactor. The adsorption and kinetic models were evaluated to
explain the adsorbed dye and dynamic reaction. The results of this study showed that
the efficiency of dye removal increased, as the contact time and adsorbent dose
increased, but as pH and initial dye concentration increased, removal efficiency
decreased. The maximum efficiency of Direct Blue 71 removal was observed at acidic
solution (pH=3), contact time of 90 minutes, adsorbent dose of 0.6 g/l and initial dye
concentration of 25 mg/l. The adsorption of direct blue 71 best fitted the Langmuir
isotherm (R2=0.87) and pseudo first order kinetic equation (R2=0.99). According to the
results obtained, multiwalled nanotubes was offered as an effective adsorbent for
removing direct blue 71.