STABILITY OF ELECTRODE

The stability of metal electrode in water depends on its corrosion characteristics, the redox potential. Most electrochemical processes use a couple of metallic electrodes, usually a relatively stable anode such as titanium and a relatively active cathode such as aluminum and iron. The redox potentials of aluminium, iron, and copper are -1.662V for Al=Al3++3e- , -0.440V for Fe=Fe2++2e- , and +0.337V for Cu=Cu2++2e- .

The more positive potential is referred to as more noble, whereas the more negative potential is referred to as more active [25]. Therefore, copper is noble like gold but aluminium and iron are easily oxidized. Such active metals can be rapidly ionized at the cathode for electrolysis of wastewater. The metal ions ejected from the cathode make various compounds with the negative ions such as phosphate in wastewater and act as a coagulant.

However, it is generally difficult to manage the electrodes for practical application of the electrolysis process for wastewater treatment because the cathode made of aluminium or iron is easily corroded with formation of surface scale and quick exhaustion. In this research, a modified electrolysis system was devised adopting a novel operation method using low current and constant voltage, and a renewable copper electrode. The simultaneous removal of organics and nutrients in agro-industrial wastewater was evaluated, and the analysis of by products from electrolysis using the copper electrode was also conducted in detail.