Dual-Functional PANI/CNF/Chitosan modified Hydrogel Composite for Electrochemical Detection and Adsorptive Removal of Heavy Metals.

 

Heavy metal pollution from industrial effluents poses severe risks to health and ecosystems, particularly in Bangladesh. This work proposes a dual-functional hydrogel composite electrode of polyaniline (PANI), cellulose nanofibers (CNF), and chitosan for simultaneous detection and removal of Cr⁶⁺ and Pb²⁺. The composite serves as (i) a thin-film on glassy carbon electrode for electrochemical detection (SWASV, CV, EIS), and (ii) a free-standing hydrogel for adsorption-based removal. This multifunctional system offers a low-cost, sustainable technic for wastewater monitoring and remediation.

Heavy metal pollution is a serious issue in Bangladesh, where industrial effluents discharge toxic Cr⁶⁺ and Pb²⁺ into rivers, causing severe health risks. Conventional detection methods (AAS, ICP-OES) are precise but costly and unsuitable for on-site use, while electrochemical sensors offer faster, cheaper detection but suffer from low sensitivity. Conventional treatments also fail to achieve both detection and removal. Conductive polymer-based hydrogels, particularly PANI integrated with chitosan and cellulose nanofibers (CNF), provide high conductivity, porosity, and abundant binding groups, making them promising for simultaneous detection and removal of heavy metals in water.

• Pb²⁺ binds via coordination (O/N donor groups). • Cr⁶⁺ binds via electrostatic attraction to protonated amines and hydrogen bonding.