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 FeO nanoparticles were fabricated by simply immersing FeO 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 FeO 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 FeO 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.