Fabrication of magnetic cobalt ferrite nanocomposites: an advanced method of removal of toxic dichromate ions from electroplating wastewater

Abstract

Magnetic cobalt ferrites (CoFe2O4) were synthesized by sol-gel method. These nanoparticles were ultra-sonicated with surface modified multi-walled carbon nanotubes (SM-MWCNTs) to form CoFe2O4/SM-MWCNTs nanocomposites. The as-prepared materials were used as an adsorbent for the removal of hexavalent chromium (Cr(VI)) arising from the presence of dichromate ions (Cr2O72− ) in the electroplating effluent. The synthesized nanocomposites were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD), Fourier transmission infrared spectroscopy (FT-IR), raman spectroscopy, thermo-gravimetric analysis (TGA), and zeta analyzer. The effect of the environmental chemistry of the solution on the adsorption has been discussed. The adsorption isotherm of Cr(VI) adsorption onto the as-synthesized CoFe2O4/SM-MWCNTs best fitted the Langmuir Adsorption Isotherm model. The high adsorption capacity of 100mg/g was achieved at 40°C under optimized conditions. Besides, the magnetic properties of synthesized CoFe2O4/SM-MWCNTs nanocomposites allow them to separate from the aqueous solution by magnetization easily. Even after seven consecutive adsorption-desorption cycles, the CoFe2O4/SM-MWCNTs nanocomposites presented an efficiency loss of less than 20% for the removal of Cr(VI) ions. This study clearly shows that cobalt nanocomposites are promising candidates in environmental applications.