Lead Scale from a Lead Pipe Detected Using Electrochemical Methods

Electrochemical methods, such as square wave voltammetry, can detect lead in drinking water. However, these methods can only detect lead ions. Lead contamination in drinking water can be from both Pb 2+ and particulate lead. Particulate lead comes from the inner walls of lead pipes and is often called lead scale. Lead scales forms from years of water with varying parameters such as pH, alkalinity, and disinfectants flowing through the pipes. The lead scale used in this work was collected from a lead pipe used in Cincinnati, Ohio. Characterization using x-ray powder diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDS) showed lead carbonate and lead oxides within the scale. These lead compounds are insoluble in drinking water which can have a pH between 7 and 9; however, if the pH is lowered to below pH 2, these lead compounds have an increased solubility. This work uses membrane electrolysis (ME) to acidify a tap water solution containing lead scale. The standard addition method is then used to collect a standard addition curve, then the unknown lead concentration from the lead scale can be calculated. Inductively coupled plasma mass spectroscopy (ICP-MS) was used as a standard method to compare the SWV results to the actual amount of lead within the unknown sample.