Preparation of core/shell nanocomposite adsorbents based on amine polymer-modified magnetic materials for the efficient adsorption of anionic dyes

This study reports on the synthesis of a core/shell nanoadsorbent based on Fe3O4 magnetic nanoparticles surface-modified with a copolymer using 2, 4-diaminophenol and formaldehyde (DAPF). We further investigated this nanomaterial as an adsorbent for removing anionic dyes, namely, amaranth (AM), orange II (OR-II) and acid red 18 (AR-18), from aqueous solutions. The fabricated Fe3O4@DAPF magnetic nanomaterials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and vibrating sample magnetometer (VSM). Various adsorption parameters were investigated, including solution pH, contact time dye concentration and temperature. Kinetic and isotherm models of the adsorption clearly indicated adsorption followed pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacities for amaranth, orange II and acid red 18 were 142.05, 121.07, and 99.60 mg g(-1), respectively. Additionally, the Fe3O4@DAPF magnetic nanomaterial was observed to have a high saturation magnetization (72.4 emu g(-1)) and thus can be rapidly separated from water using an external magnetic field. Therefore, the simple synthesis, lack of secondary pollution, rapid adsorption kinetics, large adsorption capacity and rapid separation make Fe3O4@DAPF a novel adsorbent for the rapid removal of organic dyes from aqueous solutions.