Elzinga, E.J., and D.L. Sparks. 1999. Sulfate sorption on goethite in the presence of Pb. SSSA Annual Meeting Abstracts,Oct. 31-Nov. 4, 1999 Salt Lake City, Utah. p. 218.
We studied the effect of lead (Pb) on sulfate (SO4) sorption at the goethite-water interface at pH 4.3, 5.5 and 6.0 using in situ ATR-FTIR spectroscopy. As base line information, SO4 sorption was studied in the absence of Pb over a range of SO4 concentrations. At all pH values, both inner-sphere and outer-sphere SO4 sorption complexes became more dominant with decreasing pH, and increasing SO4 concentrations. Adding Pb to the system resulted in an increase of the overall SO4 sorption and an increase in the contribution of outer-sphere SO4 complexes. This may be due to Pb competing with SO4 for inner-sphere sorption sites, and/or electrostatic effects due to inner-sphere Pb sorption. XAFS data for Pb sorbed on goethite showed that Pb forms inner-sphere complexes at the goethite surface. No differences were observed between Pb sorbed in the absence of SO4
and Pb sorbed in a system with a 500-fold excess of SO4.