Abstract
A major source of ionic copper (Cu(I) and (II)) trace metal contamination in the marine environment is the copper containing antifoulant coatings on ship hulls. Tracing this contamination is difficult. Difficult because the ionic copper released from the coatings complexes rapidly with organic and inorganic ligands in the water column. This research examines the potential for using the organic dye 2,9-dimethyl-4,7-diphenyl-1, 10-phenanthroine (BCP) embedded in the ionomeric polymer, Nafion 117, as a membrane probe sensor for quickly measuring ionic copper in seawater. Results of this study show the Nafion 117 containing BCP measures Cu(I) within 17 percent of measurements made with the Standard Method bathocuproine di-sulfonic acid (BCS) procedure. To measure total ionic copper with the membrane probe, the reductant, hydroxylamine-hydrochloride, is added to the sample. The use of the polymer with BCP allows for a rapid optical measurement. Optical measurements are possible in two ways, as a comparator and as a modification to a fiber optic probe. Response times for these devices depend on the size of the membrane used. Presently, the optical comparator using a 2 X 3 membrane takes 20 minutes to develop color. The fiber optic probe uses a 0.5 cm diameter membrane that takes 1 minute. A comparator has no electronic parts and requires only a comparison of color depth to determine the level of ionic copper in the sample. This makes it useful for monitoring. The fiber optic probe is more suitable to buoy installation and long term monitoring where data logging and archiving are needed. Therefore, the Nafion 117 polymer impregnated with BCP is a rapid method useful for detecting ionic copper released in to the marine environment.
