| More and more people have pay more attention on heavy metals because of the great dangers of heavy metals, about how to remove the heavy metals have also become a hot research in recent years, many studies show that magnetic nanoparticles because of its surface activity and superparamagnetic, showing very broad application prospect in terms of heavy metal removement. On the other hand, the molecular imprinting technique as a new molecular techniques began to enter the sight of researchers, this technique utilizes a target molecule as a template, synthetic imprinted polymers which can specifically binding to the template to achieve specific adsorption of the target molecule. Use magnetic nanoparticles as a carrier, imprinted polymer as an adsorbent, reach the dual purpose of selective adsorption and separation to the heavy metals in environmental.This paper synthetic Fe3O4 nanoparticles through a coexistence of Fe2+, Fe3+ and NH4- in sealed container reaction. Then coated a layer of SiO2 in surface of nanoparticles use ammonia reduction the ethyl orthosilicate. The preparation of imprinted polymer use cadmium ion as template molecule, ATPES as coupling agent. Then connect on the Fe3O4/SiO2 nanoparticles and elution with 2mol/L hydrochloric acid, the imprinted polymer (MIIP) contain large cadmium ion binding site. The particle size uniform, distribution between 15 to 50 nm, dispersive is good, appear a small amount of reunion. Nanoparticles magnetometer analysis of magnetic responsiveness after cladding is a small amount of reduced, but still have superparamagnetism, in additional magnetic field can realize quick separation. And XRD spectrum showed that nanoparticles appear the main diffraction peak position and relative size in conformity with the standard of Fe3O4 characteristic diffraction peak, sharp, and obvious diffraction peak sample main composition of Fe3O4 particles, good crystalline forms.Paper examines the pH, substrate concentration, time and other heavy metal ions on the adsorption process, the influence of the results shows the effects of pH value on adsorption amount is larger, when the pH value of 7, reach maximum adsorption quantity. The influence of the substrate concentration on adsorption process in, with the increase of the substrate concentration, MIIP saturated adsorption amount of cadmium first rapid increase, slow increase after, finally, when the concentration of the substrate is 60 mg/L, reach maximum adsorption quantity, using Langmuir model to fit the data after it is concluded that the theoretical maximum adsorption capacity of 24.33 mg/g. Time is one of the main factors affecting the adsorption process and adsorption process at first, the adsorption quantity increases rapidly, the adsorption of its growth speed slow gradually, starting from 4 minutes, its adsorption amount had no obvious change. Showed the MIIP to cadmium adsorption exists a maximum saturation value. With secondary dynamic equation was the biggest saturated adsorption capacity of 19.46 mg/g. In order to study the effects of other heavy metal ions on the adsorption process, the experimental setup of Cd2+ and Zn2+ and Cd2+ and Pb2+ two groups of competitive adsorption experiment, the results it is concluded that imprinted nanoparticles for the distribution coefficient of Cd2+ 187.5, far more than other ions, in the two groups of competitive adsorption experiments selective coefficient of 3.60 and 5.15, respectively, rather than mark only 0.98 and 1.12. Can explain MIIP coexistence of ion selective adsorption of target ion in the solution. |
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