Adsorption of Cr(VI) onto TiO2 from dilute aqueous solutions

Abstract

Cr(VI) adsorption onto TiO2 (anatase) particles was performed in batch equilibrium experiments. Results showed that pH was the key factor affecting the adsorption characteristics. The marked adsorption was observed under acidic condition and the adsorption capacities decreased with increasing pH, temperature, and ionic strength. The adsorption obeyed the Langmuir adsorption isotherm and the maximum adsorption capacities were determined at specific pH values. A surface complex formation model was proposed to describe the adsorption reaction between aqueous chromates and TiO2 solid surface. Because the magnitude of electrostatic energy, the adverse solvation, and lateral interaction energy which contribute to the total adsorption are relatively small in comparison with the specific chemical energy, we conclude that the specific chemical interaction is the major mechanism responsible for the adsorption process.