Conductometric Hg sensor based on polyaniline as transducer

Abstract

Mercury is a common pollutant in natural water. Several chelating agents have been used to treat mercury poisoning. Among these agents British-anti-Lewisite (dimercaprol, 2,3-dimercapto-1-propanol, BAL) is a particularly successful antidote to inorganic mercury poisoning. In the present study a conductometric electrochemical sensor for Hg²⁺ ions was developed using polyaniline as the transducer as well as the immobilization matrix and BAL as the receptor for the heavy metal ion determination. There is a release of H⁺ ions in solution when Hg–BAL complex is formed causing an increase in the conductance of the polyaniline film. The study was performed using Hg²⁺ solutions of varying concentrations prepared in 10⁻² M HCl solution as the supporting electrolyte. The polyaniline conductance was measured in the presence of different concentrations of Hg²⁺ ions. The study showed an increase in the conductance of the polyaniline film in the presence of increasing concentrations of Hg²⁺ ions at −0.2 V gate potential vs. SCE. This conductometric sensor showed a good sensitivity in concentrations as low as 10⁻¹² M of Hg²⁺ ions.

Keywords:

• Environment
• Conducting polymers
• Electrochemical sensors
• Heavy metals

Acknowledgement

One of the authors (PRS) would like to thank the Indian Institute of Technology, Bombay for the Research Fellowship during the course of this work.