Highly porous ligand-embedded carbonized metal–organic framework for the sensitive detection and removal of trace heavy metals in real samples

Abstract

As heavy metal ions severely harm human health at certain threshold concentrations, there is a critical need to develop sensitive and selective techniques for their electrochemical sensing in the environment and food samples. Thus, a smart artificial electrochemical platform was fabricated for the detection of Cd2+, Pb2+, and Cu2+ in different real samples, including vegetables (e.g., lettuce), soil, and tap water samples. It is worth mentioning that the sensitivity of the sensor was enhanced using metal–organic framework (Fe-MIL-101). Consequently, ethylenediaminetetraacetic acid (EDTA), a nitrogen-rich carbon source and chelating agent, was immobilized into the pores of the Fe-MIL-101 by facile method. Using the hydrothermal technique, MIL-101 was partially calcined at 350 °C under nitrogen to obtain highly conductive Fe2O3 doped carbon. The synergistic covalent coupling between the chelating agent, electrocatalytic active Fe2O3, and the high surface area of the carbonaceous platform effectively enhanced the sensing of the proposed metal ions. Under optimum conditions, the EDTA/C-MIl-101 (1:1) sensor exhibited superior electrochemical responses toward metal ions in the linear range from 1 μM to 100 μM with low limits of detection. Also, the proposed sensing platform can simultaneously detect these elements without any interference between their electrochemical signals, with permanent stability and good repeatability. The applicability of the fabricated materials was assessed to detect the proposed ions in different real samples, with satisfactory results (95.5–102 %).