Application of N,S-dual-doped carbon/sepiolite clay hybrid material for electrochemical detection of mercury(II) in water resources

In this work, nitrogen (N) and sulfur (S) co-doped carbon/sepiolite clay hybrid (N,S-carbon/Sep) nanostructure was synthesized via a hydrothermal approach. The morphology and structure features of the prepared material were thoroughly studied using different characterization methods. The electrochemical Hg(II) sensing capability of the N,S-carbon/Sep was studied with the modification of an inexpensive carbon paste electrode (CPE). Hg(II) determination was investigated through differential pulse anodic stripping voltammetry (DPASV) technique after closed-circuit mode. Effects of solution pH, N,S-carbon/Sep dose, accumulation potential and accumulation time on the electrochemical signal of the modified electrode were researched, and their values were determined as 5.0, 6.0% (wmodifier/wtotal), -0.7 V and 200 s, respectively. The analytical platform showed a linear range from 0.4 to 85.0 mu g L-1 with the detection limit of 0.1 mu g L-1. Moreover, the relative standard deviation (RSD) of the Hg(II) stripping peak current was 2.5% for seven repeated analyses. In addition, the interference from different metal ions (e.g., Ag(I), Pb(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Mn(II) and Cr(III)) was found negligible for Hg (II) determination using the N,S-carbon/Sep-CPE. The electrochemical sensor was applicable for analysis of spiked Hg(II) in real waters containing various ion elements.