Innovative magnetic aggregates for the removal of transition metals from industrial wastewater

A novel adsorbent material based on microaggregates of Fe3O4 magnetic nanoparticles functionalized with succinic acid has been developed. The magnetic aggregates (MA) were char-acterized in terms of the size distribution (master sizer analysis), morphology (TEM), chemical structure (IR-spectroscopy and XRD), magnetic properties (VSM), and Z-Potential. The effects of various parameters such as contact time, dosage of magnetic aggregates, the amount of succinic acid on the magnetic aggregates on the adsorption capacity, as well as the efficiency of the treatment in the adsorption of two transition metals, copper (Cu) and zinc (Zn) from real wastewater, were investigated. The kinetic behavior was analyzed by using the Lagergren pseudo-first-order, pseudo-second-order, and Elovich and intra-particle diffusion models. Langmuir and Freundlich’s models were applied to simulate the adsorption equilibrium. The magnetic aggregates reached the equilibrium condition relatively fast, within 10 min. Magnetic aggregates with a higher amount of succinic acid in their formulation showed a higher adsorption capacity of the two metals in all the experiments. This is consistent with the adsorption mechanism mainly based on electrostatic interaction between the metal ions and the negative charges on the surface of magnetic aggregates. A higher adsorption capacity for the removal of copper compared to zinc was found. Additionally, the electrochemical characterization of the magnetic aggregates was done as a preliminary study for proposing a regeneration method of the MA along with the extraction metals adsorbed based on an electrochemical process.