Mechanistic modeling of chromate adsorption onto goethite

We have investigated the adsorption of CrO42- onto goethite as a function o f pH, background electrolyte and adsorbate loading. Experimental data were interpreted with a three-plane model (TPM) that accounts for spatial charge distribution of inner-sphere surface complexes. In accordance with EXAF sp ectroscopic data [S. Fendorf, M.J. Eick, P. Grossl, D.L. Sparks, Environ. S ci. Technol. 31 (1997) 315], > (FeOCrO3-1.3)-Cr-0.2 and (> FeO)(2)(CrO2-0.6 )-Cr-0.4 surface species were selected for TPM calculations. TPM simulation s replicate CrO42- adsorption data well when CrO42- coverage was <2 x 10(-7 ) mol m(-2). (C) 2000 Elsevier Science B.V. All rights reserved.