Preparation Of Superparamagnetic Fe₃O₄ Silica Nanospheres And Its Experimental Study On Oil And Lead Removal

In recent years,various oil spill accidents have gradually shown a high incidence.Meanwhile,in some developed areas,residents'drinking water facing with the risk of lead exceeding the limit.The silica-based adsorbent material,high surface area and more pore space,becomes the good choice for oil and lead removal.In order to seek a material preparation method that can cope with both on the water and underwater application scenarios,this experiment improved the"reverse microemulsion method"by using magnetic Fe₃O₄nanoparticles(Fe₃O₄ NPs)as the core and phenyltrimethoxysilane(PTMS)as the silicon source forming the soft/hardness template.Superhydrophobic superparamagnetic Fe₃O₄nanospheres(Fe₃O₄@Si O₂)and multi-cavity superparamagnetic Fe₃O₄@Si O₂ were prepared by the same preparation method,and characterized by SEM,TEM,XRD,VSM,FTIR,etc.These were used for the removal of oil and lead ions respectively.The results of the study are as follows.1.Superhydrophobic superparamagnetic silica spheres are difficult to discuss the morphology and particle size because their surface is wrapped by PTMS and residual silanolide.Their internal cavities are also filled with phenyltrimethoxysilane,resulting in poor performance of their saturation magnetic intensity.However,the optical photographs and contact angles indicate that the silica spheres are superhydrophobic,and FTIR reveals several absorption peaks of C-H bonds,which are determined to originate from the phenyl group on PTMS,explaining the superhydrophobicity of the silica spheres.In this experiment,the effects of the preparation conditions on the morphology,particle size,magnetic saturation intensity,and specific meter of the multi-cavity-superparamagnetic silicon spheres were investigated in detail.The size and morphology of the spheres were optimized with a particle size of 296 nm,a magnetic saturation intensity of10.8 emu·g^-1,a specific surface area of 218 m²·g^-1,and a pore volume of0.132 cm³·g^-1,after reacting with 37 u L HNO₃,0.95 m L PTMS,and 150mg Fe₃O₄ in a water bath at 60°C for 3 min with mechanical stirring at 260rpm.XRD showed that the structural properties of the Fe₃O₄ core were not destroyed after calcination;FTIR showed that PTMS was removed by calcination and hydrophobicity was lost;meanwhile,VSM showed that the magnetic saturation intensity was increased after calcination.2.Superhydrophobic-superparamagnetic silica spheres were applied to the adsorption of oil slicks in water,and investigated their adsorption capacity.The results showed that the best removal effect was achieved at p H=3,25?and reaction time of 5min,when the adsorption capacity was499.81mg/g.However,the removal rate was also above 90%in acidic and neutral conditions,which was excellent and more approaching reality.The material has a better removal effect for a wide range of temperature and p H.The removal is rapid.3.The multi-cavity-superparamagnetic silica spheres were applied to the adsorption of Pb(II)in water,and investigated their adsorption capacity.The removal rate of Pb(II)reached about 94%at 25°C,p H=6,dosage8mg/L Fe₃O₄@Si O₂ with 4hours duration of adsorption,the Sorption capacity is 49.94mg/g.The adsorption process of Pb(?)by Fe₃O₄@Si O₂conforms to quasi-second-order kinetics,which is a chemisorption process.The adsorption isotherm curves showed that the adsorption of Pb(II)conforms to Freundlich isotherm adsorption model,indicated that the adsorption process was multilayered and non-homogeneous.