A facile approach towards amino-coated ferroferric oxide nanoparticles for environmental pollutant removal

A facile and environmental-friendly approach was developed to prepare magnetic nano-adsorbent for environmental pollutant removal. Based on the mussel-inspired polymerization, amino-coated Fe₃O₄ nanoparticles were fabricated by simply immersing Fe₃O₄ nanoparticles into an aqueous solution of catechol and hexanediamine with stirring at room temperature. The magnetic nano-adsorbent was characterized via Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermo gravimetric analysis (TGA), and Brunauer-Emmett-Teller's test (BET). The effects of initial mole ratio of catechol/hexanediamine and coating time on the adsorption capacity were investigated, using Congo red as a model organic dye. Under the optimal preparation condition, the absorption capacity of the amino-coated Fe₃O₄ nanoparticles reached 97.3 mg/g for Congo red, and the adsorption reached about 80% of the equilibrium adsorption amount within 200 min. Adsorption kinetics and isotherm studies indicated that the absorption process fitted the pseudo-second-order kinetic and Langmuir isotherm models well. Besides, desired functional groups could be introduced onto the surface of Fe₃O₄ nanoparticles, to tailor the adsorption capacity for Congo red, amaranths red, methylene blue and methylene violet. It is believed that the amino-coated magnetic nano-adsorbent prepared by the proposed method in this study has a good prospect for wastewater treatment.