A Selective and Sensitive Sensor for Determination of Sulfide in Aquatic Environment

A cost-effective, sensitive, and selective electrochemical sensor for the analysis of sulfide based on the high affinity of sulfide to metallic silver is proposed. To achieve high sensitivity while lowering the cost of the sensor, silver nanoparticles (Ag NPs), which possess larger metal surface area-to-volume ratio compared with bulk silver, were employed for the development of the sensor. The sensor was prepared through electrodeposition of Ag NPs on the surface of a carbon ionic liquid electrode using potentiostatic double-pulse technique, and it showed a wide linear range from 25 to 2500 $\mu $ M of sulfide with a detection limit of 6.02 $\mu $ M. Since the analysis of sulfide was performed at a remarkably low detection potential, the presented sensor offered high selectivity against common interferents and was successfully applied to the analysis of sulfide in a hot spring water sample.

I. Introduction

Hydrogen sulfide (H₂S) is a hazardous and toxic compound, which is produced both naturally and as a result of industrial activities. In nature, hydrogen sulfide is produced through decomposition of sulfur-containing organic compounds and can be found in natural gases, crude petroleum, volcanoes and hot springs. H₂S is soluble in water and, depending on pH of the solution, can dissociate to hydrosulfide anion (HS⁻) and sulfide ion (S²⁻). Due to the high toxicity of these species as well as their capability to remove dissolved oxygen, the level of total sulfide is considered as an important pollution index for water. Consequently, developing a simple, cost-effective, sensitive, and selective method for monitoring total sulfide in water samples has drawn considerable attention among scientific community [1]–[3].