SGER: NANOPOROUS THIN-FILM OXIDE ELECTRODES FOR PHOSPHATE SENSING

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

CBET-0836625 M. Anderson, University of Wisconsin Madison Intellectual Merrit: It has been shown that a phosphate sensor can be fabricated using a microporous iron oxide thin film electrode. The reduction potential of Fe (IIII) to Fe (II) is shown to be a function of phosphate concentration. The adsorption of phosphate to the surface of the iron oxides alters current vs. voltage behavior of the electrode. Phosphate levels in solution as low as 10-9M and several orders of magnitude have been measured. The hypothesis of the proposal is that the potential of the oxidation-reduction peak of iron is a function of phosphate adsorbed as well as its speciation in solution. Coupled with an in-situ pH probe and chemical equilibrium modeling using it may be possible to develop a unique sensor capable of measuring the concentration and speciation of additional analytes such as arsenates, silicates, carbonates, acetates, etc. Broader Impacts: The importance of phosphorus as the limiting nutrient in aquatic systems was first documented in whole lake fertilization experiments conducted by Schindler in the Ontario Experimental Lakes Area in 1974. Excess phosphorus can lead to undesired growth of algae and other aquatic vegetation, ultimately causing the eutrophication of natural water bodies. The development of an in-situ electrochemical phosphate sensor would allow for near-instantaneous measurements in natural waters, making analysis more convenient and less expensive. A real-time sensor would allow for the synchronization of phosphate monitoring data with transient weather events, and would facilitate rapid feedback for phosphate control strategies. While commercially available sensors exist for the nitrogen nutrients, no such sensor exists for phosphate. This proposal addresses this need. In this project, Prof. Anderson, and Dr. Isabel Tejedor, will train one PhD student. Dr. Tejedor serves as a role model for young undergraduate and graduate students and especially for woman in science and engineering. As a native Spanish-speaking person, Dr. Tejedor provides not only the academic and laboratory skills as a mentor but as well the cultural and language exposure that the students would otherwise not obtain working under the guidance of other English-speaking individuals.