ARS | Publication request: MECHANISM OF MOLYBDENUM ADSORPTION ON SOIL MINERALS EVALUATED USING VIBRATIONAL SPECTROSCOPY AND SURFACE COMPLEXATION MODELING.

Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: December 15, 2005
Publication Date: March 26, 2006
Citation: Goldberg, S.R., Johnston, C.T. 2006. Mechanism of molybdenum adsorption on soil minerals evaluated using vibrational spectroscopy and surface complexation modeling.. American Chemical Society National Meeting. Paper No. GEOC 106. Atlanta, GA, March 26-30, 2006.

Technical Abstract: Molybdenum adsorption on amorphous aluminum and iron oxides and soils was investigated as a function of solution pH and ionic strength. Vibrational spectroscopies (Raman and FTIR) were used to determine mode of bonding of adsorbed molybdate ions. The ability of the constant capacitance, diffuse layer model, and triple layer models to describe Mo adsorption on 32 soils was evaluated and compared. The models fit the data well using an inner-sphere adsorption mechanism. However, the fit at high pH was much improved using an outer-sphere adsorption mechanism in the triple layer model. A general regression model was developed for predicting soil Mo surface complexation constants from four independently measured soil chemical properties: cation exchange capacity, organic carbon content, inorganic carbon content, and iron oxide content. The model was able to predict Mo adsorption on all 32 soils. The spectroscopic information was used to choose the appropriate Mo surface complex.