Surface Modification And Applications Of Magnetic Nanoparticles

Nowadays,water pollution is one of the major challenges for environmental governance among others.Fe₃O₄ nanoparticles,a kind of catalyst with great performance,has been applied to solve the water pollution in decades).Furthermore,it can be used for catalyzing the photodegradation reactions of organic dyes,and preparing composite nanocatalysts,adsorbents,and probes when combined with other materials.In this research,nano-magnetic catalyst and nano-magnetic probe were obtained by combining magnetic nanoparticles with noble metal nanoparticles and metal fluorescent probes.Main research content are listed as below:The spherical Fe₃O₄ nanoparticles were prepared by hydrothermal method.then coated with SiO₂ by St?ber method,followed by MPTES modified on surface.The nanoparticles were characterized by Laser particle size analyzer,X ray diffraction?XRD?and transmission electron microscope?TEM?.The experiment results showed that the morphology of the spherical Fe₃O₄ nanoparticles prepared by the hydrothermal method were relatively uniform,and an average diameter of spherical Fe₃O₄ nanoparticle was observed as 229.4 nm,the diameter of silica-coated particles was increased to 286.8 nm,the surface thiol density of nanoparticles surface was calculated at 2.2×10^-5 mol/m² by Ellman method.Gold nanoparticles were synthesized by Frens method and average diameter was 21 nm.The spherical nano-magnetic catalyst was prepared by combining gold nanoparticles with magnetic nanoparticles modified by thiol.In order to investigate the catalytic performance of the catalyst,the catalyst was applied to the reaction of catalytic reduction of p-nitrophenol.The efficiency of reaction reached 92.2%after 7 recycles,it can be recovered by magnetic.The cubic Fe₃O₄ nanoparticles were prepared by hydrothermal method.then coated with SiO₂ by St?ber method,followed by MPTES modified on surface.The nanoparticles were characterized by Laser particle size analyzer,X ray diffraction?XRD?and transmission electron microscope?TEM?.The experiment results showed that the the morphology of the cubic Fe₃O₄nanoparticles prepared by the hydrothermal method were relatively uniform,and an average diameter of spherical Fe₃O₄ nanoparticle was observed as 63.1nm,the diameter of silica-coated particles was increased,the surface thiol density of nanoparticles surface was calculated at 1.78×10^-4 mol/m² by Ellman method.Gold nanoparticles and silver nanoparticles were prepared by UV-reducing supermolecular gel method,and average diameters of gold and silver particles were 3.51 nm and 2.23 nm.The cubic gold/silver loaded nano-magnetic catalyst was prepared by combining gold/silver nanoparticles with magnetic nanoparticles modified by thiol.The catalyst was applied to the reaction of catalytic reduction of p-nitrophenol,both catalysts showed good catalytic activity at room temperature,and the reaction could be completed within 20 min.The reaction could be completed within 5 minutes when the temperature rose to 60°C,The efficiency of reaction reached 89.8%and 90.2%after 10 recycles for cubic gold loaded nano-magnetic catalyst and cubic silver loaded nano-magnetic catalyst.APTES were used to functionalize the surface of Fe₃O₄ nanoparticles,Rhodamine hydrazide was synthesized from hydrazine hydrate and rhodamine B,magnetic nano-probes were prepared by combining rhodamine hydrazide and magnetic nanoparticles modified with amino groups,and the specific recognition ability of magnetic nano-probes were tested.The experiment results showed that the magnetic nano-probes could specifically distinguished Fe³⁺under the influence of coexist metal ions.It showed that fluorescence intensity and concentration of Fe³⁺presented a linear relationship in a range of 1²0?M,the detection limit was 0.168 mol/L.