Efficient removal of the organophosphate pesticide, profenofos using polymer-stabilized microporous Fe2O3-ZnO nanocomposite: Kinetic and thermodynamic analysis

Abstract

In the contemporary landscape of scientific research, the development of inhibitors for acetylcholinesterase (AChE) holds significance due to their dual application as chemical warfare agents (CWAs) and pesticides. These compounds, whether intentionally deployed for malicious purposes, used in agriculture to combat pests, or accidentally released, pose a substantial threat to humanity. Consequently, there is a dire need to create efficient nanocatalysts capable of eliminating organophosphate toxic substances. This study focuses on the synthesis of a nanocomposite catalyst comprised of polymer-stabilized Fe2O3-ZnO, characterized as porous oval-shaped clusters that exhibit exceptional proficiency in the degradation of the pesticide profenofos (PF). This degradation process is remarkably swift, occurring within a short timeframe under both dark and light conditions. Porosity enhancement was achieved through the combination of polymeric stabilizing agents, namely polyvinylpyrrolidone (PVP) and methyl cellulose (MC). Notably, the highest concentration of profenofos (1825 mg/L) was directly introduced to the Fe2O3-ZnO nanocomposite catalyst. Remarkably, 100 % degradation was achieved within just 60 min in the absence of light, highlighting the feasibility of dark treatment as an effective degradation pathway. The kinetics of the reaction were evaluated using Lagergren pseudo-first order and Ho/McKay pseudo-second order kinetic models, employing varying catalyst doses and profenofos concentrations. The results indicated that the reaction predominantly follows second-order kinetics. Furthermore, thermodynamic parameters, including the change in Gibbs free energy (ΔG), entropy (ΔS), and enthalpy (ΔH), were assessed, revealing the spontaneous and exothermic nature of the reaction. Additionally, a proposed degradation pathway for the chemical warfare agent stimulant, profenofos, was elucidated. To our knowledge, this is the inaugural documentation showcasing the remarkable efficiency of a polymer-stabilized Fe2O3-ZnO nanocomposite catalyst in degrading the organophosphate pesticide, profenofos, achieving rapid degradation rates even under dark conditions. The findings contribute to the advancement of catalytic materials for environmental remediation and provide important insights into the kinetics, thermodynamics, and degradation pathways of organophosphate compounds.