<scp>PEG</scp> ‐Modified MnFe ₂ O ₄ Nanoparticles: Polymer‐Assisted Enhancement in Photocatalytic Degradation and Mechanistic Insights

ABSTRACT Manganese ferrite (MnFe 2 O 4 , MnF) nanoparticles were synthesized via a co‐precipitation route and subsequently surface‐functionalized with polyethylene glycol (PEG) through a mass titration method. Structural and morphological analyses (SEM, XRD, EDX, FTIR) confirmed a monophasic cubic spinel structure with an average crystallite size of 23 nm and a slight grain growth after PEG modification. DM simulation revealed the homogeneous grafting of PEG without interfering with the parent spinel structure of MnF. Magnetic measurements (VSM, ZFC) revealed superparamagnetic behavior for pristine MnF ( M s = 37.25 emu g −1 ) and a transition to weak ferromagnetism for PEG@MnF ( M s = 22.7 emu g −1 ), attributed to surface modification. Dielectric studies further highlighted the multifunctional nature of the material. Photocatalytic performance was evaluated via the degradation of thiamethoxam, a widely used pesticide. Under optimal conditions (80 min, 10 ppm, 0.04 g catalyst, 65°C), PEG@MnF exhibited significantly enhanced degradation efficiency compared to unmodified MnF, owing to improved dispersibility, reduced agglomeration, and a higher density of active sites imparted by PEG. Degradation intermediates were identified using GC–MS and FTIR, and a plausible degradation pathway was proposed. These results demonstrate that PEG functionalization markedly improves the magnetic, dielectric, and photocatalytic performance of MnF, establishing PEG@MnF as a promising catalyst for sustainable environmental remediation.