Synthesis of magnetic multi-walled carbon nanotube via solvent free direct doping of iron oxide nanoparticles for dye removal

Abstract

Magnetic multi-walled carbon nanotubes (MMWCNTs) of c-MMWNCTs and s-MMWCNTs were synthesized using direct doping method of iron oxide nanoparticles (Fe₃O₄) with c-MWCNTs and s-MWCNTs respectively. Reflux under nitric acid (HNO₃) was used to graft –COOH group onto pristine MWCNTs and thermal decomposition of ammonium sulphate was performed to graft –HSO3 group onto c-MWCNTs in order to increase the hydrophilic properties, improve dispersibility and provide site for metal and other ion attachment before doping with Fe₃O₄. Result from FT-IR indicated the present of –COOH group and –SO₃H group on c-MWCNTs and s-MWCNTs respectively. Meanwhile, SEM and FT-IR analysis confirmed the successful deposition of Fe₃O₄ onto c-MMWCNTs and s-MMWCNTs. pH stability test indicated that lowest detachment was found on pH 7 for both MMWCNTs and s-MMWCNTs showed higher stability than c-MMWCNTs at pH 3,7 and 9. Ultrasonication test implied that s-MMWCNTs exhibited higher stability than c-MMWCNTs under different ultrasonication time. Both c-MMWCNTs and s-MMWCNTs were applicable for MB adsorption. In short, s-MMWCNTs with higher stability in different pH and ultrasonication time emerged as a promising magnetic adsorbent to be used in waste water treatment.