Electroanalysis of copper as a heavy metal pollutant in water using cobalt oxide modified exfoliated graphite electrode

Copper is one of the heavy metals that have been recognized as essential for living organisms in trace amounts as a cofactor for crucial enzymes. However, excess amount of this trace element can have serious health effects. It is therefore important to monitor Cu in drinking water as it can easily be overlooked due to its biological functions. An electrochemical technique using re-compressed exfoliated graphite modified with cobalt oxide nanoparticles was evaluated as an electrochemical sensor for the detection of Cu2+ in spiked water samples. The analysis involved an accumulation step at −500 mV while stirring followed by square wave-anodic stripping voltammetry (SW-ASV). The accumulation step resulted in the reduction of Cu2+ ions in solution onto the electrode surface which were subsequently stripped off on the second step resulting in an analytical current signal. The electrodeposition time and potential were first optimised and the best conditions were used to get a detection limit of 94 μg L−1. This sensor was used for Cu analysis in real water samples using standard addition method with percentage recoveries of between 99% and 101%.