Controlled synthesis of 2,4,6-trichlorophenol-imprinted amino-functionalized nano-Fe3O4-polymer magnetic composite for highly selective adsorption

Four kinds of novel amino functionalized core-shell molecularly imprinted magnetic polymers (nFe(3)O(4)@NH2MIP) were synthesized via suspension polymerization and surface imprinting technique. Different amines, i.e., ethylenediamine (EDA), diethylenetriamine (DETA), triethylentetramine (TETA) and tetraethylenepentamine (TEPA), were used for surface grafting. The obtained nFe(3)O(4)@NH2MIP were named as nFe(3)O(4)@EDAMIP, nFe(3)O(4)@DETAMIP, nFe(3)O(4)@TETAMIP and nFe(3)O(4)@TEPAMIP, respectively. The as-prepared nFe(3)O(4)@NH2MIP were fully characterized. Batch adsorption experiments of nFe(3)O(4)@NH2MIP showed that specific selectivity and remarkable adsorption capacity to 2,4,6-trichlorophenol (2,4,6-TCP) can be obtained. Mechanism studies suggested that the excellent adsorption properties were closely relied on hydrogen bonding, which are strongly related to the amino groups grafted on the surface of the magnetic polymers. Kinetic studies showed that the adsorption of 2,4,6-TCP by nFe(3)O(4)@NH2MIP followed pseudo-second-order models, with the adsorption rate constants, k(2), at 0.00394-0.02209 g/(mg min), suggesting chemisorption processes. Both the adsorption rate constants (k(2)) and the initial adsorption rates (k(2)q(e)(2)) of the nFe(3)O(4)@NH2MIP were higher than those of the non-molecularly imprinted magnetic polymers (nFe(3)O(4)@NH2NIP). The existing of the surface imprinting cavities might be favorable for the mass transfer to accelerate the adsorption process, thus, leading to a faster adsorption process. Thermodynamic studies suggested that the adsorption processes fit the Freundlich isotherms well. The adsorption capacity of nFe(3)O(4)@NH2MIP was found to be 872.8, 880.5, 888.3, 898.7 mg/g with the imprinting factor (alpha) toward 2,4,6-TCP at 2.68, 2.31, 2.22, 2.03, for nFe(3)O(4)@EDAMIP, nFe(3)O(4)@DETAMIP, nFe(3)O(4)@TETAMIP and nFe(3)O(4)@TEPAMIP, respectively. Three kinds of real environmental water samples were treated by the as prepared nFe(3)O(4)@NH2MIP. The results proved that these materials could be a series of great potential reusable adsorbents for selective removal of 2,4,6-TCP in environmental water. (C) 2015 Elsevier B.V. All rights reserved.