Magnetite decorated multi-walled carbon nanotubes for removal of toxic dyes from aqueous solutions

The removal of malachite green (MG) and rhodamine B (RB) from aqueous solutions was studied by batch adsorption technique using Fe3O4/MWCNT. Fe3O4/MWCNT adsorbent was synthesized by co-precipitation method and characterized by XRD, SEM, and TGA. 94 % MG removal and 98 % RB removal were achieved in 80 min using 10 mg adsorbent, at pH 6 and 298 K. The effects of adsorbent amount, pH, initial dye concentration, contact time, and temperature were investigated. Equilibrium data were well fitted by Langmuir adsorption model and pseudo-second-order kinetic model. MG adsorption on Fe3O4/MWCNT is exothermic and RB adsorption is endothermic in nature.