A novel magnetic Fe3O4 carbon-shell (MFC) functionalization with lanthanum as an adsorbent for phosphate removal from aqueous solution

Magnetic Fe3O4 carbon-shell (MFC) functionalization with lanthanum (MFC@La(OH)(3)) was successfully synthesized with various weight ratios between Fe and La utilizing the facile procedure to obtain high adsorption capacity and an easily separable adsorbent from water. FTIR result showed La-OH vibration bond and the residual NO3- anion confirming the La functional group's successful formation on the surface of the outer carbon shell of the magnetite core. Furthermore, the asymmetric stretch vibration of the P-O group within the HPO42- and H2PO4- species of phosphate confirmed the adsorption phosphate on the surface layer of the adsorbent. The MFC@La(OH)(3) 1:2 has the highest BET surface area among the other adsorbents and is selected as the highest adsorbent for phosphate removal. It was discovered that the adsorption capacity increased at pH 4-6, which can be attributed to La(OH)(3) functional group which was protonated (positively charged), thus provoking an electrostatic interaction reaction with the negatively charged phosphate species. The equilibrium data were fit into various adsorption isotherms and found to fit well with the Freundlich model (indicating that novel adsorbent had heterogeneous surface and multilayer adsorption mechanism processes) with a maximum adsorption capacity of 30.85 mg P/g, whereas the adsorption kinetics followed pseudo-second-order kinetics. After adsorption, the magnetic separation was easily achieved, and the adsorbent could be regenerated continuously for five cycles. The current study found that the novel adsorbent has high adsorption capacity, easy to separate and recover, and appropriate for further investigation of large-scale water and wastewater treatment applications.