Enhanced Peroxidase Mimetic Activity of Magnetic Porous Carbon (MPC) Utilized in Colorimetric Sensing of Hg (II) Ions in Aqueous Medium

Abstract A new sensitive colorimetric sensor was designed to investigate the presence of Hg 2+ in aqueous solution by using Fe 3 O 4 NP impregnated on carbon nanocomposite(MPC) synthesized from MIL88 A which possess an excellent peroxidase mimicking activity that brings oxidation of 3, 3’, 5, 5’‐ tetramethylbenzidine (TMB) under the influence of hydrogen peroxide (H 2 O 2 ) to produce blue colour in the solution. The solution was decolorized by the addition of Glutathione (GSH) which restores the TMB radical cations and ceased the oxidation reaction. Addition ofHg 2+ ions to the solution bring back a strong blue colour due to the strong affinity of Hg 2+ with the thiol groups of GSH which promote the oxidation of TMB in the solution. Based on these strategies, we have developed a sensitive andselective colorimetric sensor for the determination of Hg (II) in aqueous solution with the detection limit value of 236 pM and a linear relationship of R 2 =0.994. The proposed mechanism was successfully implemented for the detection of mercury in real water samples for environmental applications.