BIOMASS-MODIFIED CARBON-PASTE ELECTRODES FOR MONITORING DISSOLVED METAL-IONS

Electrodes were prepared by incorporating dried, nonliving biomass of a common lichen, Ramalina stenospora, and Sphagnum (peat) moss in carb on paste. The electrodes were tested on solutions containing Pb(II) an d Cu(II) ions by immersing the electrode in the solution for selected periods of time to accumulate ions. Following this the electrode was c onnected to a potentiostat and the applied voltage scanned from -1.0 t o +0.5 V vs. SCE. Any adsorbed metal ions were stripped back into solu tion at the appropriate oxidizing voltage. The ratio of biomass to min eral oil to graphite has been found to be crucial to electrode perform ance. Different ratios of the three components using the lichen Ramali na stenospora were evaluated for maximum electrode performance. Only t wo electrode compositions gave a good electrode response for lead. Ele ctrodes containing peat moss were superior in performance to lichen-co ntaining electrodes for lead. Electrodes based on the lichens Cladina evansii and Letharia vulpina, the marine algae Ulva lactuca and Sargas sum fluitans, the blue-green alga Spirulina platensis, and the aquatic plant Eichhornia crassipes did not respond to lead at all. All functi oning electrodes studies showed a poor response toward copper(II) ions . (C) 1998 Elsevier Science B.V.