EXAFS studies of the chemical state of lead and copper in corrosion products formed on the brass surface in potable water

Corrosion products formed on the surface of lead-containing brass were examined using grazing incidence fluorescence EXAFS. The corrosion scales were shown to be comprised by malachite Cu₂(OH)₂CO₃ and hydrocerussite Pb₃(OH)₂(CO₃)₂. The equatorial and axial Cu-O distances in the corrosion deposits were virtually the same as in the reference malachite sample, whereas the disorder in the Cu-O distances in the corrosion products was enhanced. The chemical environment around the Pb atoms in the corrosion deposits was similar to that in hydrocerussite but there was an apparent shortening of the Pb-O nearest neighbor distances in the corrosion deposits compared to those in pure hydrocerussite.