A porous polyaniline-chitosan nanocomposite for efficient adsorption and detection of the pesticide Sumithion from water

The environmental persistence of organophosphate pesticides necessitates the development of multifunctional materials capable of simultaneous remediation and monitoring. This study introduces a bifunctional polyaniline-chitosan (PANI-Ch) nanocomposite, synthesized via in-situ oxidative polymerization, designed for the high-capacity adsorption and quantitative optical detection of the pesticide Sumithion. The PANI-Ch platform exhibited an exceptional adsorption capacity of 124.7 mg/g, following a Langmuir-type monolayer process. Thermodynamic and spectroscopic analyses revealed a physisorption mechanism dominated by π–π stacking and hydrogen bonding, supported by a mean free energy (E) of 0.027 kJ/mol. Beyond remediation, the nanocomposite functions as a robust sensing tool; Sumithion adsorption induces precise, concentration-dependent FTIR spectral shifts in the O–H/N–H and C = C stretching regions. These optical changes allow for trace-level quantification with a Limit of Detection (LOD) of 0.5 ppb. By integrating high efficiency scavenging with built-in analytical signaling, this nanocomposite provides a versatile and advanced platform for integrated water treatment and real-time environmental monitoring.