Study On Removal Of Typical Organic Compounds By Poly 4-vinylpyridyl-based Magnetic Nanomaterials

Water pollution poses a serious threat to public health and ecosystems.Therefore,it is significant for us to control and repair water pollution.Adsorption method is considered as a promising technology due to its wide-ranging availability of adsorbents,simple and easy operation,high efficiency,low cost and good reusability.At the same time,oxidation/reduction techniques have received widespread attention for the removal of organic pollutants in water where organic pollutants could be degraded into less hazardous small molecule forms even inorganic substances.The paper aimed to design and synthesize a series of novel magnetic nanocomposites with CoFe₂O₄ or Fe₃O₄ as the magnetic media and poly-4-vinylpyridine?P4VP?as a functional matrix,in order to obtain efficient removal of organic pollutants in water.The main contents and conclusions of the study were as follows:1.Three kinds of P4VP-based magnetic nanocomposites?GO-Fe₃O₄@P4VP,Al-MOF-Fe₃O₄@P4VP and CoFe₂O₄-P4VP@Ag NPs?were designed and synthesized.The physicochemical properties of the three kinds of P4VP-based magnetic nanocomposites were analyzed and characterized with scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,elemental analysis,Brunauer-Emmett-Teller?BET?,X-ray diffraction?XRD?,X-ray photoelectron spectroscopy?XPS?,fourier transform infrared spectroscopy?FTIR?,vibrating sample magnetometer?VSM?,plasma emission spectrometry?PES?and high-resolution continuum source atomic absorption spectrometer?AAS?.2.The results showed that the GO-Fe₃O₄@P4VP had high surface area,rough surface,porous structure and magnetic properties.The adsorption capacity of GO-Fe₃O₄@P4VP for typical dye methyl blue?MB?increased with the increase of MB initial concentration,and the maximum adsorption amount could reach 152.51mg/g.The optimal pH for GO-Fe₃O₄@P4VP to adsorb MB was 2.5.The increase in ionic strength enhanced the adsorption of MB on GO-Fe₃O₄@P4VP.The equilibrium adsorption and kinetic process of MB on GO-Fe₃O₄@P4VP could be well described by Freundlich isotherm and the pseudo-second-order kinetic model,respectively.Five adsorption-desorption cycles showed that GO-Fe₃O₄@P4VP had good reusability and stability.3.Al-MOF-Fe₃O₄@P4VP had high surface area,porous structure,rough surface and magnetic property.The maximum adsorption capacity of Al-MOF-Fe₃O₄@P4VP for typical medicines and personal care products?PPCPs?naproxen?Npx?could reach up to 31.67 mg/g.The adsorption equilibrium process could be well described by Freundlich isotherm indicating that Npx was a multilayer adsorption on Al-MOF-Fe₃O₄@P4VP.The adsorption rate of Npx on Al-MOF-Fe₃O₄@P4VP was very fast and the kinetic process conformed to the pseudo-second-order kinetic model.In addition,as the temperature increased,the adsorption of Npx on Al-MOF-Fe₃O₄@P4VP was also increased,which indicated that the adsorption of naproxen on Al-MOF-Fe₃O₄@P4VP was a spontaneous,endothermic and increased randomness process.The increase of ionic strength inhibited the adsorption of Npx on Al-MOF-Fe₃O₄@P4VP.The adsorbent exhibited good adsorption ability even after ten adsorption-desorption cycles.The adsorption mechanisms of Npx on Al-MOF-Fe₃O₄@P4VP might involve?-?interaction,electrostatic interaction,hydrogen bonding and hydrophobic reaction.4.In the presence of NaBH₄,CoFe₂O₄-P4VP@Ag NPs was used as highly efficient catalysts for the removal of Rhodamine B?RhB?and Ciprofloxacin?Cip?in water.Nearly 99.4%of RhB?20 mg/L?was decolorized in 20 min under the condition of 0.2 g/L CoFe₂O₄-P4VP@Ag NPs with 10 mM of NaBH₄.81.5%of Cip?9 mg/L?was removed in 180 min under the same experimental conditions.CoFe₂O₄-P4VP@Ag NPs showed good reusability and stability,and 92.5%of RhB could be removed after six cycles of reuse.Furthermore,the intermediate products were identified and the possible mechanism and pathways of CoFe₂O₄-P4VP@Ag NPs for degradation of Cip were proposed.