The effect of phosphate and calcium on the electrochemical measurement of lead-ions in water
Abstract
The cathodic deposition and anodic stripping of lead on a gold electrode in water gives a linear response for lead in the concentration range 0 to 50 parts per billion (ppb Pb+2) when the water is an anaerobic solution of sodium sulfate dissolved in distilled water with the pH adjusted to 7 and the conductivity is between 300 to 900µS/cm. These levels of lead-ion in water span from safe to unsafe for human consumption. Unfortunately, ions found in real drinking water, e.g., phosphate, distort the current response during the anodic stripping of lead from gold. The presence of these ions like phosphate distorts the correlation between the response of anodic stripping of lead from a gold electrode and the concentration of lead in water. The work here is to investigate the mechanism of the distortion of the anodic stripping of lead from the gold surface in the presence of ions found in real water. In particular, does the lead form insoluble precipitates in the presence of these ions, thereby lowering the concentration of soluble lead-ions in water? Or does the complexation between lead-ion and other ions found in real water shift the potential of electrochemical deposition and anodic stripping? Or is there some combination of these 2 effects? Or something else? To answer the above questions, the main approach is to use inductively coupled plasma Ð mass spectroscopy (ICP-MS) to measure the levels of lead-ion in synthetic water without and with ions found in real water. The lead levels in a water sample as found by ICP-MS will be compared to the lead levels in the same water as found electrochemically, that is by the anodic stripping of lead from gold using rapid pulse voltammetry. Learning this mechanism will give new knowledge about the charge transfer characteristics of lead-ion with a solid electrode, and will also impact development of a convenient point-of-use way to measure the levels of a hazardous material, lead, in the drinking-water supply.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 30, 2022
- Source ID
- W911NF2210112
Entities
People
- Dominic Gervasio
Organizations
- Army Contracting Command
- United States Army
- University of Arizona