A novel and biocompatible Fe3O4 loaded chitosan polyelectrolyte nanoparticles for the removal of Cd2+ ion.

In this work, Fe3O4 loaded chitosan (CS) nanoparticles (NPs) and microparticles (MPs) were synthesized based on ionic gelation technology for the removal of Cd2+ ion. The influencing parameters including initial concentration, pH, contact time and recycling was evaluated and optimized. The results showed that particle size of Fe3O4 loaded CS NPs and MPs was in the range of 164.05-768.69 nm, and the former showed relatively higher adsorption capacities (97.86 mg/g) on Cd2+ ion than the latter after 90 min at pH 5.0 for the solutions with initial Cd2+ ion of 100 mg/L, respectively. Brunauer, Emmett and Teller (BET) test illustrated 61.48 m2/g of specific surface area, 0.0274 cm3/g of pore volume and 6.03 nm average pore size. The results of FT-IR, TEM, EDS and XRD indicated that Fe3O4 was well incorporated into CS NPs and MPs. Moreover, the adsorption equilibrium data fitted well with Langmuir isotherm model and adsorption process followed the pseudo-second-order model. The adsorption mechanisms could be well explained though coordination and electrostatic attraction. Findings of this work highlighted the potential using Fe3O4 loaded CS NPs as an effective and recyclable adsorbent for the removal of heavy metal ions in industrial wastewater treatment.