Synthesis of molecular printed amino-functionalized nano-Fe₃O₄-polymer magnetic composite and its adsorption properties on 2, 4, 6-trichlorophenol in seawater

In order to realize selective adsorption and removal of 2, 4, 6-trichlorophenol (2, 4, 6-TCP) in seawater, a 2, 4, 6-trichlorophenol-imprinted amino-functionalized nano-Fe₃O₄-polymer magnetic composite (nFe₃O₄@MIPNH₂-polymer) was synthesized via ultrasonic assisted suspension polymerization. The composition, structure, morphology and magnetism of nFe₃O₄@MIPNH₂-polymer were characterized by means of Elemental Analysis (EA), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The application for its adsorption and removal properties on 2, 4, 6-TCP pollutant from seawater was investigated. The results show that the nFe₃O₄@MIPNH₂-polymer has an average size of around 800 nm, with the saturation magnetization intensity of 32.6 emu·g^-1. Adsorption isotherm of 2, 4, 6-TCP onto nFe₃O₄@MIPNH₂-polymer accords with Langmuir model, which demonstrate an excellent adsorption capacity with the maximum adsorption capacity at 105.26 mg·g^-1, much higher than that of none-molecular imprinted amino-functionalized nano-Fe₃O₄-polymer magnetic material (nFe₃O₄@NH₂-polymer, with the maximum adsorption capacity at 76.92 mg·g^-1). The isothermal adsorption curve mainly obeys the Langmuir mode. The adsorption thermodynamic studies suggest that the adsorption processes of the 2, 4, 6-TCP by the nFe₃O₄@MIPNH₂-polymer are endothermic, entropy favored, and spontaneous in nature, and the adsorption processes reach the equilibrium within 5 min and the kinetic data are well fitted to the pseudo-second-order model. The activation energy for the 2, 4, 6-TCP removal is 78.0 kJ·mol^-1. There is almost no interference by the coexisting components in seawater for the adsorption of 2, 4, 6-TCP. The nFe₃O₄@MIPNH₂-polymer can be reused at least 5 times after elusion. The 2, 4, 6-TCP in seawater can be selectively and effectively removed by the nFe₃O₄@MIPNH₂-polymer.