Characterization of deposits by direct observation and by electrochemical methods on a conductive transparent electrode. Application to biofilm and scale deposit under cathodic protection

A new device is proposed where the electrode is a transparent electrode in modified SnO2. With this new electrode the reduction of oxygen occurs in a way similar to a gold electrode. Simultaneously the oxygen current is recor ded versus time and picture of the interface itself is taken with a digital camera through the electrode. An image analysis is performed to determine the coated area and the number of objects by surface unit. Under cathodic p rotection, the reduction of oxygen induces an increase of the interfacial p H and then formation of scale deposit. The usual chronoamperometric analysi s was completed by an in situ observation of the scale deposit. In natural water the biofilm. development was studied by electrochemical method to det ermine the biofilm thickness and this analysis is completed by a direct obs ervation through the electrode. A good correlation between the two techniqu es was found. (C) 2001 Elsevier Science Ltd. All rights reserved.