A study of sorption of cadmium by goethite in aqueous solution

Abstract

Investigation has been carried out on the potential of a locally sourced goethite for the removal of cadmium ion from aqueous solutions using batch equilibration technique. The maximum uptake of cadmium is 6.4 x 10-2 mg/g-goethite. The sorption kinetics appears to be rapid as equilibrium was attained within a period of 1 hour. The highest sorption capacity was obtained for particle size with diameter (Φ) 0.09 mm. Both infrared spectrophotometric and X-ray diffraction (XRD) techniques have also provided evidence for cadmium fixation on to the surface of the goethite. The sorption mechanism appears to follow Langmuir adsorption isotherm model. The Langmuir constants K and Xm (mass of Cd2+ required to form monolayer on the entire surface of the goethite) were 0.096 mg/g-goethite and 0.075 mg/g-goethite, respectively.