AWWA WQTC71526

In this study, the dissolution rates of pure plattnerite (ß-PbO₂) were investigated as a function of pH, dissolved inorganic carbon (DIC), orthophosphate, and the presence of chloramines. A continuous stirred tank reactor (CSTR) loaded with 1 g/L of plattnerite was used to measure the lead dissolution rates. The lead concentration and pH of the effluent were monitored continuously and reached steady-state values within one day. The dissolution rates were on the order of 10^-10 mol/m²-min. At all pH values studied (7.5, 8.5, and 10), the dissolution rate increased with increasing DIC, probably due to the formation of soluble Pb-carbonate complexes. The fastest dissolution rates were observed at the lowest pH of 7.5. The initial PbO₂ solid and possible transformation products were characterized by X-ray diffraction. Includes 16 references, figures.