Adsorption of Methyl orange dye from Water solutions by carboxylate group functionalized multi-walled Carbon nanotubes

The present study was carried out to investigate the potential of carboxylate group functionalized Multi-walled carbon nanotubes (MWCNT−COOH) adsorbent for the removal of Methyl orange (MO) textile dye from aqueous solutions. The effects of pH, shaking time and temperature on adsorption capacity were studied; the contact time to obtain equilibrium at 298 ˚K was fixed at 25 min. The effect of temperature on adsorption process was evaluated from 298 to 338 ˚K. Results showed that removal of Methyl orange increased with increasing contact time and decreased with increasing pH and temperature. For Methyl orange dye, the equilibrium data were best fitted to The Langmuir isotherm model. The adsorbent was characterized by infrared spectroscopy, and scanning electron microscopy. The pseudo-second-order kinetic model provided the best fit to the experimental data compared with The Elovich or pseudo-first-order or intra-particle diffusion kinetic adsorption models.