Removal of methyl blue from aqueous solution by magnetic carbon nanotube

Magnetic carbon nanotube (mCNT) was formed via direct mixing of carbon nanotube (CNT) with magnetic nanoparticle (MNP) in dye solution. When the mass ratio of MNP to CNT was 4:1, all CNT were magnetically collected. The adsorption performance of mCNT was evaluated using methyl blue (MB) as a model adsorbate. Equilibrium of MB adsorption was attained in 60 min, and maximum adsorption occurred at pH 3–6. MB adsorption was independent of ionic strength and followed pseudo-second-order kinetics. According to the Langmuir isotherm, adsorption capacity of mCNT for MB was 115.34 mg g⁻¹. Thermodynamic analysis suggested MB adsorption onto mCNT was a spontaneous process. Reusability study results showed that 97.06, 96.26, 94.33, 92.91 and 90.14% of MB were removed in five consecutive cycles. The study suggests that the mCNT has a great potential application in dye removal from industrial wastewater.