Highly Precise and Sensitive Approach for Direct Electrochemical Sensing of Phosphates Using Zinc Ferrite Impregnated-Polyaniline Coated Electrodes

Abstract Phosphate is a non-point pollution source that primarily arising from agricultural waste water run-off and industrial effluents which proliferate the natural eutrophication. There is a need of effective monitoring of excessive phosphate release into aquatic environment. Some developments in direct electrochemical sensing have recently been made where the protocols often rely on time-consuming and complicate process for electrode fabrication while using some toxic metals. This article outlines efficient strategy for preparation of sensing electrodes for quick-responsive and real-time detection of phosphate ions based on conductive polyaniline (PANI) with biocompatible iron oxide (Fe2O3), zinc oxide (ZnO) and zinc ferrite (ZnFe2O4). It has been shown that the electrochemical integration of metal oxide particles into the porous PANI backbone offers several advantages, including high selectivity for target ions and rapid response to analytes in less than 50 seconds, along with low limit of detection (LOD). Among the different sensor electrodes LOD value was found to be 2.95 x 10− 7 M, with high diffusion coefficient values of 9.6x10− 4 cm2/s and high sensitivity of 1.22 A/M·cm² for PANI-ZnFe2O4@AuS modified gold sheet (AuS) electrode. The sensing features of the as-prepared PANI-ZnFe2O4@AuS electrode can be attributed to the uniform distribution of metal oxide particles within the PANI matrix, which produces effective synergistic effect for phosphate ions sensing.