Jeremy May

Major: Chemistry

Faculty Advisor: Frank Cheng

Project Title:

Tailoring the Electrochemical Hypochlorite Sensitivity of GUITAR with Electro-Amination

Abstract

The electrochemical grafting of surface functional groups is a dynamic technique used to modify an electrode material for tailored applications.  Literature evidence suggests that the addition of amine functional groups will enhance detection of hypochlorite in aqueous sample matrices. Hypochlorite, or free chlorine, is commonly used in water disinfection as well as a number of industrial processes. In order to improve the sensitivity to hypochlorite, amine functional groups were electro-grafted to the surface of GUITAR (a defect rich derivative of graphite). The grafting was performed by anodic oxidation of ammonium carbamate in a pH 7 phosphate buffer. The amination successfully reduced the overpotential and enhanced the sensitivity towards hypochlorite. However, a control experiment of the electrode oxidized in the absence of ammonium carbamate (just the background buffer) reduced the overpotential by the same quantity and enhanced the sensitivity to an even greater degree. This revealed that oxygen functional groups formed during the oxidative grafting, and not the amine groups, were responsible for the enhanced hypochlorite sensitivity. This study highlights the importance of running control experiments to verify causal relationships, as well as widely believed (but unverified) claims from literature.