Detection, formation and reactivity of Tetravalent Lead Corrosion Product (PbO2) and its role in Water Quality in Drinking Water Distribution System

Abstract

Tetravalent lead corrosion product (PbO2) has been linked to lead contamination in drinking water. However, the accurate measurement of PbO2 in drinking water sample has been shown challenging, the kinetics of PbO2 formation is unknown and the stability of PbO2 in chloraminated drinking water is not fully elucidated. In this thesis, a modified iodometric method was developed for accurate measurement of PbO2 in drinking water. This method was then employed to quantitatively determine the kinetics of PbO2 formation from the chlorination of Pb(II) carbonate solids. The obtained rate equations suggested that PbO2 formation is first-order with respect to the available Pb(II) solid surface area, free chlorine concentration and OH- concentration, respectively. Investigation on the stability of PbO2 in NH2Cl solutions containing Br- indicated that the reductive dissolution of PbO2 can be accelerated via Bromide-catalyzed NH2Cl decomposition.