Design of a Schiff base-modified chitosan hydrogel electrochemical sensor for the simultaneous detection of phenolic pollutants in seawater

A novel electrochemical sensor based on Schiff base-modified chitosan (PY-CH) hydrogel for the simultaneous recognition of catechol (CC) and hydroquinone (HQ) phenolic pollutants in seawater is presented. CC and HQ are hazardous pollutants frequently present in industrial wastewater and marine environments. Their persistence, toxicity, and potential for bioaccumulation pose significant risks to aquatic ecosystems and human health. The PY-CH hydrogel was synthesized via a Schiff base condensation reaction between amino groups of chitosan and 1-pyrene carboxaldehyde, forming a stable imine bond. The synthesized composite PY-CH was characterized by FTIR, XRD, TGA, and SEM to confirm its structural, thermal, and morphological properties. The successful surface modification and enhanced electron transfer properties of the PY-CH/SPCE modified electrode were confirmed by Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using ferrocyanide as a standard redox probe. Square wave voltammetry (SWV) technique demonstrated the selective electrocatalytic affinity of the PY-CH/SPCE sensor for CC and HQ, showing distinct and well-separated oxidation peaks. The sensor exhibited wide linear ranges, excellent sensitivity, and low detection limits of 0.86 μM for CC and 0.937 μM for HQ, with high selectivity versus potential interfering species. Furthermore, the sensor's practical applicability was validated by seawater analysis, achieving high recovery rates of 99.150% for CC and 99.154% for HQ, confirming its high accuracy and reliability. These results highlight the PY-CH/SPCE sensor as an eco-friendly, low-cost and efficient tool for the sensitive determination of phenolic pollutants in complex environmental matrices.