Magnetically recoverable SDS-Functionalized PPy@Fe 3 O 4 nanocomposite for highly efficient removal of Brilliant Green dye from water

Synthetic dyes discharged from industrial processes pose significant environmental and health risks, necessitating efficient and reusable treatment technologies. In this study, a magnetically recoverable Fe3O4@PPy@SDS nanocomposite was synthesized through in situ polymerization and investigated for the adsorption of Brilliant Green (BG) dye from aqueous solution. The formation of the Fe3O4@PPy@SDS nanocomposite was confirmed using various characterization techniques. The nanocomposite exhibited spherical Fe3O4 particles with an average size of approximately 14 nm distributed on the PPy surface, with a specific surface area of 12 m2 g−1 and a saturation magnetization of 10.08 emu g−1. Batch adsorption experiments were conducted by systematically varying the adsorbent dosage, solution pH, contact time, initial BG concentration, and temperature. The nanocomposite exhibited equilibrium adsorption capacity of 22.79 ± 0.14 mg g−1 at pH 6. The adsorption equilibrium was best described by the Langmuir isotherm, yielding a monolayer capacity of 29.25 ± 2.31 mg g−1 (R2 = 0.99), while kinetic data followed the pseudo-second-order model (R2 = 0.99), and thermodynamic studies indicated a spontaneous and endothermic adsorption process. The adsorption mechanism was attributed to electrostatic attraction, π-π interactions, and hydrogen bonding, between BG and the functionalized nanocomposite surface. Furthermore, the adsorbent retained around 20 ± 0.41 mg g−1 of capacity after five regeneration cycles, demonstrating excellent reusability. The combination of high adsorption capacity, facile magnetic separation, and regeneration capability highlights the potential of Fe3O4@PPy@SDS as a reusable adsorbent for treating cationic dye-contaminated water.