Polyaniline‐Coated Iron‐Rich Coal Fly Ash Nanocomposite for Efficient Removal of Cr (VI) from Tannery Effluent

Abstract This study presents a low‐cost, eco‐friendly synthesis of a novel nanocomposite (IRCFA‐PANI@Ag NC) composed of iron‐rich coal fly ash (IRCFA), polyaniline (PANI), and silver nanoparticles derived from floral waste. The NC exhibits a high Cr (VI) adsorption capacity of 512.82 mg/g at pH 5.0 and demonstrates excellent regeneration and recyclability. Adsorption data fitted the Langmuir isotherm model, indicating monolayer adsorption. Kinetic studies indicated rapid uptake and strong affinity toward Cr (VI), while thermodynamic analysis confirmed the spontaneous and favourable nature of the process. The incorporation of PANI improved surface functionality, while silver nanoparticles enhanced stability and increase surface area resulting in superior adsorption and reusability. Regeneration experiments demonstrated excellent recyclability over multiple cycles without significant loss of efficiency. The synergistic interaction of IRCFA, PANI and silver nanoparticles enhances the NC stability, reusability, and Cr (VI) removal efficiency, positioning IRCFA‐PANI@Ag NC as a promising candidate for industrial wastewater treatment.