Abstract
A tetraethylenepentamine (TEPA)-functionalized nano-Fe3O4 magnetic composite material (nFe3O4@TEPA) was synthesized by a facile one-pot solvothermal method. It was characterized by elementary analysis (EA), powder X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The results show that the nFe3O4@TEPA has an average size of ∼20 nm, with a saturation magnetization intensity of 48.2 emu g−1. Its adsorption properties were investigated by adsorbing fluorine ions, phosphate, Cr(vi) and their co-existing water system. The adsorption performance was studied as a function of solution pH, initial concentration of ions, contact time and temperature for each ion. The adsorption of the multi-ion co-existing system was studied via batch tests, XPS and FTIR analyses. The effect of co-existing ions was studied through Box-Behnken Design (BBD) and response surface methodology (RSM). It can be deducted that the adsorption mechanism of an individual fluorine ion or phosphate was mainly related to electrostatic attraction, while that of Cr(vi) might be mainly related to electrostatic attraction and coordination interactions. For the fluorine ion and phosphate bi-component system, their adsorption was competitive via ion exchange. For the Cr(vi), fluorine ion and phosphate tri-component co-existing system, Cr(vi) took priority for adsorption and could replace the absorbed fluorine ion or phosphate by competitive reaction, but not vice versa.
Highlights
Elevated levels of oxyanions and monoatomic anions have been found in the environment and they can be harmful to both humans and wildlife.[1,2,3] Some of these anions have become the most frequently detected in ground water at hazardous waste sites and have been placed on the top of the priority list of toxic pollutants by the U
A tetraethylenepentamine (TEPA)-functionalized nano-Fe3O4 magnetic composite materials was synthesized by a facile one-pot solvothermal method. It was characterized by elementary analysis (EA), powder X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS) and vibrating sample magnetometer (VSM)
U 1⁄4 Dw=Dn; Dn 1⁄4 niDi ni; Dw ni Dii 4 ni Di 3 i1⁄41 i1⁄41 where U is the polydispersity index, Dn is the number-average diameter, Dw is the weight-average diameter, and Di is the diameter of the determined microspheres. It revealed that the nFe3O4@TEPA particles were multidispersed with some aggregation at an average diameter of around 20 nm (Fig. 1(a)), with Dn at 21.5, Dw at 22.8, and U at 1.06
Summary
Elevated levels of oxyanions (e.g. arsenite, arsenate, chromate, phosphate, selenite, selenate, borate, nitrate, etc.) and monoatomic anions (e.g. uoride, chloride, bromide, and iodide) have been found in the environment and they can be harmful to both humans and wildlife.[1,2,3] Some of these anions have become the most frequently detected in ground water at hazardous waste sites and have been placed on the top of the priority list of toxic pollutants by the U. EPA.[4] Treatment of anion-containing wastewater prior to discharge is essential Conventional techniques, such as reduction, reverse osmosis, electrodialysis, ion exchange, and adsorption, have been used for removing these anions from wastewater.[5,6] the reduction followed by precipitation has some disadvantages, i.e., higher waste treatment equipment costs, signi cantly higher consumption of reagents, and signi cantly higher volume of sludge generated.[7] reverse osmosis and electrodialysis are superior in recovering some of the oxyanions, such as Cr(VI), it is difficult to Recently, Fe3O4-based magnetic nanoparticles (MNPs) have found to be simple, convenient, and powerful approaches for the separation and puri cation of environmental samples, and removal of toxic pollutants, including various ions, in water.[9,10,11,12,13,14,15] most reports are focused on the treatment of one-ion component solution. It is necessary to investigate the simultaneous removal process in multi-component system containing oxyanions and monoatomic anions
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