Synthesis and characterization of Schiff base ligand-mutliwalled carbon nanotubes as mercury-free electrochemical sensor for detecting toxic metals in aquatic treatment

Abstract

The aspire of the present investigation is to develop a novel mercury-free electrochemical sensor for the sensitive detection of toxic pollutant in environmental sources. The synthesis of N,N′-bis(salicylaldehyde)-1,2-diaminobenzene (BSD) as a pre designed Schiff-base ligand (SBL) coated on surface of multi-walled carbon nanotubes (MWCNTs) modified working electrode for the detection of Pb2+ and Hg2+ in various water sources. The role of BSD contains hydroxyl and imine ions acting as active sites to detect the metal ions in 0.1 M of acetate buffer solution. A star like crystal structure for BSD/MWCNTs modified surface of electrode was observed using SEM analysis. The conductance (σ) for PIG electrode (unmodified), MWCNTs modified and BSD/MWCNTs modified electrodes are 4.7 × 10−5 S cm−1, 408.1 × 10−5 S cm−1 and 553.2 × 10−5 S cm−1 were estimated. BSD/MWCNTs modified electrode shows the best conductivity compared with other electrodes. For the selective detection of Pb2+ and Hg2+, the square wave anodic stripping voltammetry (SWASV) was utilised. The linear range of Pb2+ and Hg2+ in the concentration from 2.0 to 155 nM and limits of detection for Pb2+ and Hg2+ were observed at 0.3 nM and 0.6 nM by SWASV. This sensor is often used for sensitive detection of analytes like Pb2+ and Hg2+ in different water samples. The results of SWASV recovered value are comparing with atomic absorption spectroscopy (AAS).