Preparation Of Three-dimensional Composite Adsorbent Materials And Their Application In Oil-water Separatio

The natural leakage of oil in the ocean,the oil spill problem of offshore oil exploration and the occurrence of tanker accidents have caused serious environmental damage,which not only affects biodiversity,but also threatens marine ecological balance.At present,gravity sedimentation,chemical flocculation,biological treatment and in-situ combustion are mostly used to clean up the spilled oil,but these methods may have adverse effects on marine organisms,or the cleaning speed is too slow to control the diffusion of spilled oil in time.In addition,the cleaning efficiency of these methods is greatly affected by the location of oil spill and weather conditions.In view of the above problems,porous adsorbents with hydrophobicity and lipophilicity are used to clean up and recover oil spills on sea level.Common porous adsorbents include carbon nanotube aerogels,graphene,porous boron nitride and polymer sponges.However,these adsorbents have problems such as low wettability,poor structural stability,and low reusability during oil-water separation.It is also difficult to quickly adsorb high-viscosity heavy oil at room temperature.Therefore,it is urgent to design an oil-water separation adsorption material with recyclable and continuous purification characteristics.In this paper,two different composite functional porous materials were prepared by electrospinning and dip coating,and the continuous and efficient recovery of crude oil was realized by thermal assisted combination.The main research contents are as follows:1)Polyvinylidene fluoride/SiO₂@graphene oxide（PVDF/SiO₂@GO）aerogels is prepared by electrospinning polyvinylidene fluoride/SiO₂（PVDF/SiO₂）nanofiber membrane and graphene oxide（GO）crosslinking.In this process,the content of SiO₂ nanoparticles in the PVDF fiber membrane is changed to control the porosity and surface roughness of the composite aerogel,and the composite aerogel with the best performance is obtained.PVDF/SiO₂@GO aerogel has a stable structure,excellent oil absorption capacity(129-264 g g^-1)and better reusability;after acid-base pretreatment,it still maintains high hydrophobicity,which indicates that it has great chemical resistance.More importantly,PVDF/SiO₂@GO aerogels can separate oil-water mixtures by gravity with high separation flux(42402 L m^-2 h^-1)and separation efficiency（99.96%）.In addition,under the irradiation of sunlight,aerogels can heat up rapidly,effectively reducing the viscosity of surrounding crude oil and enhancing its fluidity.2)A non-contact responsive superhydrophobic SiO₂ aerogel blanket is developed by layer-by-layer assembly of MXene and Fe₃O₄/polydimethylsiloxane（PDMS）along the SiO₂aerogel blanket（SAB）skeleton.This composite aerogel blanket exhibits excellent compressive strength（compressive stress 70.69 k Pa）,superhydrophobicity（water contact angle 166°）and corrosion resistance（weak acid/strong alkali）.Fe₃O₄/MXene@SiO₂ aerogel blanket（Fe₃O₄/MXene@SAB）has high hydrophobicity and stable porous structure,which can successfully separate oil-water mixture.The separation flux is 1.50-3.19×10⁴ L m^-2 h^-1,and the separation efficiency is 99.91-99.98%.In addition,this responsive Fe₃O₄/MXene@SAB exhibits excellent magnetic heating and solar heating conversion efficiency,even under relatively low magnetic field and sunlight,high viscosity crude oil can be continuously separated from seawater by pump combination.The PVDF/SiO₂@GO aerogel and Fe₃O₄/MXene@SiO₂ aerogel blanket proposed in this paper provide an effective solution for solving large-area viscous crude oil leakage.