Electrocatalysis of Endosulfan Based on Fe₃O₄: An Experimental and Computational Approach

Abstract

The present work reports the electrocatalytic oxidation of the organochlorine pesticide endosulfan (EDS) using iron oxide (Fe3O4) nanoparticles synthesized from Callistemon viminalis leaf extracts. As a sensor for EDS, Fe3O4 was combined with functionalized multiwalled carbon nanotubes (f-MWCNTs) on a glassy carbon electrode (GCE). Cyclic voltammetry, electrochemical impedance spectroscopy, and the differential pulse voltammetry experiment were conducted to investigate the electrochemistry of EDS on the GCE/f-MWCNT/Fe3O4 sensor. Based on optimized experimental conditions, the reports of analytical parameters show a limit of detection of 3.3 μM and an effective sensitivity of 0.06464 μA/μM over a range of concentrations from 0.1 to 20 μM. With the proposed method, we were able to demonstrate recoveries between 94 and 110% for EDS determinations in vegetables. Further, a series of computational modeling studies were carried out to better understand the EDS surface adsorption phenomenon on the GCE/f-MWCNT/Fe3O4 sensor. The highest occupied molecular orbital–lowest unoccupied molecular orbital (HOMO–LUMO) energy gap (−5.18 eV) computed by density functional theory (DFT) supports the layer-by-layer electrode modification strategy’s charge transfer and stability. Finally, transition state modeling was able to predict and confirm the mechanism of endosulfan oxidation.

Large Computational Survey of Intrinsic Reactivity of Aromatic Carbon Atoms with Respect to a Model Aldehyde Oxidase

“…AutoTS relies on the quantum chemical package Jaguar , for all quantum mechanical calculations which are performed at the level of DFT. Numerous applications of AutoTS to different reaction types have been published. − In this work, AutoTS is applied to the oxidation reaction involved in AOX metabolism. Not only do we report the intrinsic reactivity of over 1000 aromatic carbon atoms in one of the largest computational efforts of this kind to date, but we were able to obtain a level of thoroughness in our results not attempted before, considering CS and multiple stereochemical pathways possible for the oxidation reaction.…”