A novel sensor for the determination of Hg2+ in waters based on octadentate ligand immobilized multi-walled carbon nanotube attached to paraffin wax impregnated graphite electrodes (PIGE)

In this work, the synthesised octadentate ligand immobilised multi-walled carbon nanotubes (MWCNTs) modified electrode as an electrochemical sensor of Hg 2+ is reported. The octadentate/MWCNTs composites were coated on the polished surface of paraffin impregnated graphite electrode for fabricating the enhanced electrochemical sensing platform for Hg 2+ determination. The octadentate ligand contains four N and four O donor atoms which coordinate with the metal ion in stripping medium have been investigated. Surface morphology of the fabricated modified electrode was studied using scanning electron microscope (SEM). The modified electrode was characterised by electrochemical impedance spectroscopy (EIS) and square wave anodic stripping voltammetry (SWASV). Further various factors such as preconcentration time, effects of pH and different electrolytes were optimised for the detection of Hg 2+ . Under the optimised condition, anodic stripping voltammetry of Hg 2+ showed a response in a linear range from 2.4 - 180 nM and the limit of detection was 0.8 nM for Hg 2+ ( S / N = 3). Interference studies with Cd 2+ ,As 3+ ,Cu 2+ , Ag + ,Ni 2+ ,Fe 3+ ,Zn 2+ ,Sn 2+ and Pb 2+ showed an insignificant effect on the electrochemical response of Hg 2+ . The proposed modified electrode exhibited an excellent performance with good reproducibility, selectivity and stability. The practical application of the modified electrode was also evaluated by the detection of Hg 2+ in well water and lake water samples with good recovery results.