Atmospheric pressure preparation of superhydrophobic surface-modified SiO2 aerogel for oil-water separation

The hydrophilicity and high cost fabrication of aerogels have limited their applications in oil-water separation. Herein, we prepared a novel SiO 2 aerogel using a simple atmospheric pressure drying method and surface silylation modification, with methyl trimethoxy silane (MTMS) and tetraethyl orthosilicate (TEOS) as co-precursors. The experimental results demonstrated that enhancing the degree of methyl group substitution during surface silylation significantly influenced the structure and hydrophobic properties of the SiO 2 aerogel. As the methylation level increased, the bulk density exhibited a notable reduction from 0.216 to 0.094 g·cm −3 , the water contact angle increased from 140° to 152°, porosity rose from 90.18 % to 95.72 %, and particle size gradually reduced. The TMCS-modified SiO 2 aerogel exhibited excellent adsorption rates for soybean oil, dichloromethane, n-hexane, and vacuum pump oil, and has certain separation effect for oil-water emulsion. It still maintained good hydrophobicity under various pH conditions and intact after over 20 adsorption cycles of n-hexane and dichloromethane. We believe that this superhydrophobic and low- cost oil-absorption material has great potential in the actual treatment of oil spill pollution.