METHYLENE BLUE ADSORPTION IN AQUEOUS SOLUTION USING ACTIVATED CARBON AND ACTIVATED CARBON MODIFIED WITH ZnO NANOPARTICLES

Abstract

Activated carbons and activated carbons modified with ZnO nanoparticles were prepared mixing agricultural wastes like corn cob or red mombin seed with the activating chemical agent, ZnCl2, in a weight ratio 1:1 or with ZnCl2 and zinc acetate in a weight ratio 1:1:0.5 in aqueous medium, respectively. Pellets were obtained from this slurry and were dried before being carbonized. The resulting material was repeatedly washed with a solution of HCl 0,5 M and abundant distilled water to finally be dried at 100°C for 12 h in the form of pellets, which were crushed and sieved to a size smaller than 0,25 mm.

A Field Emission Scanning Electron Microscope was used to characterize the different morphologies of the ZnO nanoparticles on the surface of the obtained activated carbon which depended of the raw material used to produce the activated carbon, however in both samples the presence of ZnO was detected by X-ray diffraction. Adsorption kinetic studies performed with methylene blue shown that the activated carbons based on corn cob, modified with ZnO, improved its kinetic process under UV radiation. However bare activated carbons had better adsorption properties than the activated carbons modified with ZnO most probably due to the fact that ZnO nanoparticles could cover active sites of the activated carbon.