Iron catalyst supported over magnesium oxide had been synthesized with different percentages of Fe, i.e., 0.5, 1, and 5% employing the method of impregnation. These fabricated catalysts were used to grow carbon nanotubes (CNTs) using a chemical vapor deposition (CVD) method in the CVD reactor. The 5% Fe/MgO catalyst showed the maximum growth of CNTs. The synthesized novel CNTs (5Fe-CNTs) were investigated for their adsorption capabilities for the removal of parts per million levels of hexavalent chromium from electroplating effluent. The 5Fe-CNTs were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), and Zeta analyzer. The 5Fe-CNTs showed remarkable adsorption capacity of 63.3 mg g-1 toward Cr(VI) in water. The effects of various operating conditions on the removal of Cr(VI) from wastewater have been evaluated. Kinetic and thermodynamic studies were performed, and it was observed that the experimental data is in best agreement with pseudo-second-order kinetics. Besides the synthesized CNTs exhibited good recyclability for adsorbing Cr(VI) as even after 3 adsorption cycles, the adsorption capacity was reduced by less than 10%.
Keywords: CNTs; CVD; Chromium; Electroplating; Nanotechnology; Wastewater treatment.