Electroanalysis of Cd 2+ and Pb 2+ Based on Bi/Fe 3 O 4 /RTIL Electrode

Bi-based electrodes for detection of Cd2+ and Pb2+ have been widely reported; however, few were reported about the electroanalysis of Cd2+ and Pb2+ by variation of electrode materials in fixed Bi3+ concentration. Herein, two types of Fe3O4 with large size (400–500 nm) of Fe3O4 (LFe3O4), small diameter (40–60 nm) of Fe3O4 (SFe3O4) synthesized by two methods, and Fe3O4/RTIL (room temperature ion liquid) composite were used to perform the individual and simultaneous detection of Cd2+ and Pb2+. The materials were characterized by spectra and electrochemical methods. Under the optimized condition, the electrochemical behaviors of Cd2+ and Pb2+ were analyzed by limiting of detection (LOD) and sensitivities. The detection effect of SFe3O4 was better than that of LFe3O4. The LOD of Bi/SFe3O4/RTIL electrode in the individual detection for Cd2+ and Pb2+ reached 1.6 and 2.4 nM, and the sensitivities are 38.3 and 25.49 μA/μM, respectively. The LOD of Bi/SFe3O4/RTIL electrode was 2.5-fold lower, and the sensitivities were 1.7-fold higher than those of SFe3O4. The Bi/SFe3O4/RTIL electrode exhibited the lowest LODs and the highest sensitivities among three electrodes. The effect of individual detection among three electrodes was better than the simultaneous. The proposed electrode also performed the analysis of real sample. The analytical method could provide a reference for sensitive detection of other heavy metal ions. Two kinds of Fe3O4 particles synthesized with small and large sizes, and Bi/Fe3O4/RTIL composite was modified electrode to carry out the detection of Cd2+ and Pb2+ individually and simultaneously.