Sustainable Au (III) adsorption using greenly Fe-BTC/PpPDA synthesized composite: kinetic and isothermal studies

A novel porous composite material, Fe-BTC/PpPDA, was synthesized via a green solvothermal route by integrating polyparaphenylenediamine (PpPDA) into the Fe-BTC metal-organic framework. The material was characterized by X-ray diffraction, FTIR, ultraviolet-visible and scanning electron microscopy/energy-dispersive X-ray spectroscopy analyses, confirming successful incorporation of nitrogen-rich PpPDA into the metal organic frameworks structure. The composite exhibited a well-developed porous morphology and abundant functional groups favourable for metal binding. Batch adsorption experiments demonstrated a high gold uptake capacity (q _max = 1045.8 mg g^-1) with rapid kinetics, reaching equilibrium within 30 minutes. The adsorption behaviour followed the Langmuir model (R² = 0.9847), indicating monolayer adsorption and high selectivity. These findings position Fe-BTC/PpPDA as an efficient, sustainable and selective adsorbent for gold recovery from polymetallic aqueous solutions.