Electrochemical Dissolution and Quantification of Lead Phosphate Scales from Lead Pipes

Abstract Orthophosphate is a common inhibitor used to prevent dissolved lead leaching from the pipes into drinking water. Lead phosphate scales can aggregate over time, detach, and cause severe water contamination. Accurate quantification of Pb requires rigorous acid treatment to obtain a sample that is free of insoluble particles. This paper describes the use of membrane electrolysis for the reagent-free dissolution of real lead phosphate scales collected from corroded pipes. The method allows for the in-situ generation of acidic environment, which in the combination with anodic stripping voltammetry provides a powerful tool for the accurate and reagentless quantification of Pb in contaminated water samples. The integration of the sample preparation and voltammetric detection in a single unit allows for the autonomous operation with minimal attention, making this method suitable for the development of on-site quantification devices. This technique has been successfully applied to electrochemically dissolve and quantify highly insoluble lead phosphate in tap water, allowing the complete dissolution and accurate voltammetric quantification of particulate Pb without any external acid addition for treatment of the tap water samples. The results were in a good agreement with inductively coupled plasma-mass spectrometry measurements, showing ≤14% relative error.