Preparation And Properties Of Superhydrophobic-superoleophilic Aerogels

The efficient use of resources and the protection of ecological environment have become the urgent problems to be solved in the development of contemporary society.Absorption and recovery of liquids play a vital role in many industrial and environmental applications,such as cleanup and recovery of oil spills,chemical spills,etc.In recent years,common porous materials have emerged continuously,but it have not been able to achieve the compatibility of intelligent oil-water identification and high-efficiency absorption performance.How to effectively improve the oil-water identification and absorption capacity of porous materials has become a huge challenge.In this paper,a stable suspension system was prepared by hydrophobic modification of silica（SiO₂）nanoparticles,selective oxidation of cellulose,and polyurethane dispersion.On this basis,a superhydrophobic-superoleophilic aerogels with directional pores structure was constructed by using the ice template directional freezing method.The effects of polyurethane,cellulose,and hydrophobic SiO₂ nanoparticles content on the structure and properties of aerogels were investigated by scanning electron microscopy and contact angle measurement experiments.The performance of the aerogel was evaluated by absorption and flow resistance experiments,and the unique directional pore structure in the aerogel was revealed to be the reason for its high absorption speed,large absorption capacity and low flow resistance.The results indicated that the SiO₂ nanoparticles modified by n-octyltriethoxysilane have a water droplet contact angle of about 157.5°and a dodecane droplet contact angle of about 0°,showing excellent superhydrophobic-superoleophilic.The carboxylation of nanocellulose was controlled by the 2,2,6,6-tetramethylpiperidine oxide（TEMPO）selective oxidation method,and the oxidized cellulose with a carboxyl group content of about 300 mmol/kg,600 mmol/kg,and 1200 mmol/kg were prepared.According to the dispersion state and dispersion stability of the dispersion,a stable suspension was prepared.On this basis,aerogels with superhydrophobic-superoleophilic directional pore structure were prepared by ice-template method.The aerogel has excellent absorption selectivity and absorption speed for organic varieties solvents.The results of the absorption experiment and the flow resistance experiment show that the directional pore structure can greatly reduce the flow resistance and energy loss of the liquid during the absorption process,and effectively promote the rapid and efficient absorption of oil by the aerogel.