Development of a PVDF-CoFe2O4 Electrocatalyst Modified Pencil Graphite Electrode for Nanomolar-level Detection of 4-Aminophenol in Tablets Contaminated Pharmaceutical Waste-water Samples

Abstract

4-Aminophenol (4-AP), widely used in pharmaceuticals, dyes, and photographic chemicals, poses serious environmental and health risks due to its toxicity and persistence. Conventional detection methods such as chromatography and spectrophotometry are reliable but costly, time-consuming, and require complex preparation. Electrochemical sensing provides a faster and more sensitive alternative. Nanocomposite-modified electrodes can further enhance sensitivity, with polyvinylidene fluoride (PVDF) offering excellent conductivity and cobalt ferrite (CoFe₂O₄) contributing redox activity and stability. CoFe₂O₄ nanoparticles with a cubic spinel structure were synthesized by a sol–gel method and blended with PVDF (1:10 w/w) to form a nanocomposite. This was drop-cast onto a pencil graphite electrode (PGE) to prepare PGE/PVDF-CoFe₂O₄. The material was characterized by XRD, FTIR, and FESEM, while electrochemical performance was assessed using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The PGE/PVDF-CoFe₂O₄ electrode showed strong electrocatalytic activity for 4-AP reduction, achieving a linear detection range of 5–200 nM, a detection limit of 0.33 nM, and high sensitivity (23.03 μA·nM⁻¹·cm⁻²). Real wastewater analysis confirmed excellent recovery and reliability. The synergistic effects of PVDF conductivity and CoFe₂O₄ electrocatalysis enabled efficient electron transfer, establishing the nanocomposite as a promising transducer for environmental and pharmaceutical monitoring.

Graphical Abstract