Efficacious Removal of Cd²⁺ and Pb²⁺ Ions from Wastewater Using a Novel Fe₃O₄/SiO₂/PANI-SDBS Nanocomposite

The current work synthesizes and characterizes a new Fe₃O₄/SiO₂/PANI-SDBS nanocomposite designed as an efficient adsorbent for the removal of Cd²⁺ and Pb²⁺ ions from contaminated water. The process includes the polymerization of aniline on the Fe₃O₄/SiO₂ nanocomposite in the presence of SDBS. The Fe₃O₄/SiO₂/PANI-SDBS nanocomposite was characterized by using a variety of techniques, including FT-IR, XRD, TEM, SEM, BET, TGA, zeta potential measurements, and particle size distribution analysis, to evaluate its magnetic, structural, and surface properties. For the elimination of both Cd²⁺ and Pb²⁺ ions, ideal adsorption parameters were examined, including pH, adsorbent dose, and contact duration. The solution medium's optimal pH for achieving the highest effectiveness of elimination for both metal ions was decided to be 7.0. The Fe₃O₄/SiO₂/PANI-SDBS adsorbent demonstrated high adsorption capacities for both Pb²⁺ (72.20 mg g^-1) and Cd²⁺ (67.84 mg g^-1) at pH 7, with corresponding removal efficiencies of over 94.10% and 77.47%, respectively. This efficiency is attributed to the composite's large specific surface area and the strong binding affinity of its PANI and SDBS functional groups toward heavy metal ions. Multilayer adsorption on heterogeneous surfaces was shown by isotherm analysis that matched the Freundlich model and adsorption kinetic investigations that showed strong conformance with pseudo-second order for both metal ions. The thermodynamic study proves endothermic and spontaneous process for the removal of metal ions. Furthermore, the adsorbent may be readily recovered from solution thanks to the magnetic core, and regeneration by acid treatment enables reusability with consistent adsorption efficiency across several cycles, making it a cost-effective and sustainable option for continuous water purification processes. Its high adsorption capacity and reusability also make it suitable for use in emergency-response situations, such as the rapid cleanup of wastewater.