Unleaded Drinking Water: Equilibrium Potential Measurements for Monochloramine Disinfectant

Presenter Information

Brandi Clark

Department

Chemistry

Research Advisor

Switzer, Jay

Advisor's Department

Chemistry

Abstract

The strength of monochloramine, NH₂CI, as an oxidizing agent can be linked to its effect on Pb levels in drinking water. In this study, the equilibrium potential was measured as a function of pH from pH 8 to 12 and compared to a theoretical plot of formal potentials derived from the Nemst equation. The measured equilibrium potential was consistently about 300 mV more negative than the calculated potential - NH₂CI is a weaker oxidizing agent than predicted. When the measured potentials are plotted on a Pourbaix diagram, it is found that NH₂CI can oxidize Pb to PbO₂ only above pH 9.5, while the theoretical values indicate that it can do so at a much lower pH. The validity of the values measured in this experiment is supported by the fact that NH₂CI has been shown to oxidize Pb to Pb²⁺, not PbO₂, at pH 8 (1). The work is important because it is known that PbO₂ acts as a passivating agent on the inside of lead-bearing plumbing materials.

Presentation Type

Oral Presentation

Document Type

Presentation

Recommended Citation

Clark, Brandi, "Unleaded Drinking Water: Equilibrium Potential Measurements for Monochloramine Disinfectant" (2007). Opportunities for Undergraduate Research Experience Program (OURE). 194.
https://scholarsmine.mst.edu/oure/194