Current methods to measure trace concentration of heavy metals are expensive, time consuming and require extensive sample preparation. They are designed for centralized laboratories with highly trained personnel and not suitable for on-site measurements. There is an urgent need to come up with an innovative detection mechanism that can provide low detection limits with enhanced sensitivity for real time on-site measurements with minimal sample preparation. A novel ultrasensitive, selective and low cost electrochemical sensor based on hollow sphere bismuth oxide doped mesoporous carbon aerogel nanocomposite derived from sustainable biomass material (corn) was successfully fabricated for simultaneous Pb2+ and Cd2+ detection at picomolar levels. The as prepared material was characterized with SEM, XRD, RAMAN, BET, FTIR and EIS methods and revealed a good physicochemical properties. In this nanocomposite material, we successfully brought together the advantages of an extraordinary large surface area carbon with mesopores for analyte preenrichment, and excellent electroanalytical activity of bismuth oxides hollow sphere structure for highly sensitive heavy metal sensing was attained. Under optimized conditions, this electrode material exhibited a very low detection limit of 1.72 pM for Pb2+and 1.58 pM for Cd2+ in ambient conditions, the lowest ever limit of detection recorded for detection of both Pb2+ and Cd2+ using activated carbon. Two linear detection ranges were observed, 0.5 to 10 pM and from 15 to 100 pM, due to the existence of combined micro- and mesopores adsorption phenomena. The electrochemical measurements were repeated using the same electrode and across different electrodes and exhibited an RSD of 2.77% for Cd2+, 2.94% for Pb2+, 3.19% for Cd 2+ and 3.56% for Pb2+. The nanocomposite sensor material demonstrated excellent reproducibility and great resistance to interference. Furthermore, the application for real water analysis was demonstrated and the result was highly consistent with the measurement from ICP.

Ultra-trace electrochemical sensing of heavy metals using nanostructured bismuth doped carbon complex: Real time on site environmental application

253rd National Meeting (2017)

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