Fabrication of a selective mercury sensor based on the adsorption of cold vapor of mercury on carbon nanotubes: Determination of mercury in industrial wastewater

A new sensor for the determination of mercury at μg ml−1 levels is proposed based on the adsorption of mercury vapor on single-walled carbon nanotubes (SWCNTs). The changes in the impedance of SWCNTs were monitored upon adsorption of mercury vapor. The adsorption behaviour of mercury on SWCNTs was compared with that on multi-walled carbon nanotubes (MWCNTs) and carbon nanofibers (CNFs). Cold vapor of mercury was generated at 65 °C using Sn(II) solution as a reducing agent. The limit of detection was 0.64 μg ml−1 for Hg(II) species. The calibration curve for Hg(II) was linear from 1.0 to 30.0 μg ml−1. The relative standard deviation (RSD) of eight replicate analyses of 15 μg ml−1 of Hg(II) was 2.7%. The results showed no interfering effects from many foreign species and hydride forming elements. The system was successfully applied to the determination of the mercury content of different types of wastewater samples.