Adsorption of cobalt onto activated charcoal and its utilization for decolorization of bromocresol green dye

Activated charcoal was prepared from pine tree cones and was treated with 5M HNO₃ and HCl solutions. The acid-treated charcoals (ATC) were used for the adsorption of cobalt ions from aqueous solution and then utilized for the decolorization of bromocresol green (BG) dye in aqueous medium. The adsorption study revealed that ATC adsorbed 9.063 mg/g of cobalt within 2 h. The ATC and cobalt-adsorbed ATC (Co-ATC) were characterized by scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). The SEM images showed that Co nanoparticles are adsorbed and dispersed on the surface of ATC. The presence of Co nanoparticles was also confirmed by EDX. The decolorization study was carried out using UV/Vis spectrophotometry and the results revealed that ATC decolorized 16.85% of the dye while Co-ATC decolorized about 40.5% of the dye within 12 h.