Electrochemical detection for Hg 2+ ion based on hydrazine-montmorillonite intercalation compound as potentiometric electrode

Abstract

Hydrazine-montmorillonite (HYD-MMT), intercalation compound was prepared to construct potentiometric electrode for the determination of Hg2+ ion. The results of X-ray diffraction spectrometry (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) mapping techniques revealed that the hydrazine was completely intercalated in the interlayer space of montmorillonite. This intercalation compound (HYD-MMT) was used to construct as potentiometric electrode and compositions were optimized. The composition of the hydrazine-montmorillonite (HYD-MMT) intercalation compound: graphite: epoxy resin of 20:20:60 % wt gave compatible slope with the Nernstian theory for Hg2+ ion. Potentiometric results of electrode provided the slope with 29.431.49 mV decade-1, LOD 5.26x10-6 M within linear concentration range 10-6-0.1 M. The selectivity coefficient was performed by separate solution method and results presented that this electrode provided good selectivity for Hg2+ ion. Electrochemical impedance spectroscopy (EIS) was used to study electron transfer and behavior at the surface of electrodes, the results indicated that hydrazine in montmorillonite structure could help increase electron transfer at the surface electrode during performing Hg2+ ion solution. This electrode was successful to determine Hg2+ ion in real soil sample from rice field.