The role of electrochemistry and electrochemical technology in environmental protection

For decades electrochemical technology has contributed successfully to environmental protection. In addition, environmental electrochemistry is capable of giving a huge contribution to further reach this goal by (1) application and improvement of existing technology, and (2) research, development and implementation of new technology. There is a tendency in the metal finishing and metal processing industries to redesign processes as closed loop systems. Therefore, we think especially the purification of dilute heavy metal ion-containing process liquids needs much of our attention. Electrochemical processes relevant to this purpose are considered and examples of (possible) industrial applications are discussed. Moreover, a critical evaluation of the usefulness of different types of electrodes is given. Generally, the two-dimensional electrode is the most favourable electrode configuration: the static flat electrode at high flow rates and in combination with mass transfer promoters, and the rotating disc electrode at high peripheral velocity. In both cases turbulent flow condition at the electrode are preferred to enhance the mass transfer. For redox systems where both the reactant and the product are soluble, the porous electrode is favourable due to its high specific surface area.