XAS study of AsO43− and SeO42− substituted schwertmannites

Synthetic schwertmannite samples with varying amounts of arsenate and selenate substituting for sulfate were examined by XAS methods in an attempt to characterize the location of the anion complexes. Selenate appears to both substitute directly for sulfate within tunnels in the structure, and sorb onto the outside of crystallites. No disruption of the basic structure appears with selenate substitution. However, arsenate appears mainly to sorb to the outside of crystallites, destabilizing the structure and poisoning growth.