Environmental pollution is the most serious issues facing this world today, especially when we talk about several contaminants which invaded waste water and caused health hazards. Therefore, we have focused on the elaboration of nanocomposite as catalyst to eliminate dyes from aqueous solutions by using adsorption process. We have succeeded in synthesizing magnetite multi-walled carbon nanotubes by co-precipitation method, the characterization of this material by the X-Ray diffraction (XRD) showed a presence of the magnetite on the surface of the carbon nanotubes. Kinetic study indicated a rapid increase in the adsorption capacity of Bromocresol purple (BCP) dye, the equilibrium time took about 25 minutes. Besides, thermodynamic study indicated   that adsorption of the organic pollutant on magnetic-MWCNT was a spontaneous and exothermic process. Furthermore, the adsorption isotherm represented perfectly by the Langmuir model and the value calculated by Freundlich model indicated that the adsorption was favorable. In conclusion, our study showed that the catalyst could be manipulated magnetically and exhibited good and fast adsorption capacity because of the magnetite properties and the huge specific area of carbon nanotubes.

Keywords: Magnetite carbon nanotubes, catalyst, adsorption.