ADSORPTION OF CR(VI) ONTO TIO2 FROM DILUTE AQUEOUS-SOLUTIONS

Cr(VI) adsorption onto TiO2 (anatase) particles was performed in batch equilibrium experiments. Results showed that pH was the key factor af fecting the adsorption characteristics. The marked adsorption was obse rved under acidic condition and the adsorption capacities decreased wi th increasing pH, temperature, and ionic strength. The adsorption obey ed the Langmuir adsorption isotherm and the maximum adsorption capacit ies were determined at specific pH values. A surface complex formation model was proposed to describe the adsorption reaction between aqueou s chromates and TiO2 solid surface. Because the magnitude of electrost atic energy, the adverse solvation, and lateral interaction energy whi ch contribute to the total adsorption are relatively small in comparis on with the specific chemical energy, we conclude that the specific ch emical interaction is the major mechanism responsible for the adsorpti on process. (C) 1997 IAWQ. Published by Elsevier Science Ltd.