Oil/water separation with hydrophobic/oleophilic silica-shelled cellulose aerogels

Abstract

In this work, hydrophobic/oleophilic cellulose/SiO2 aerogels are prepared by coating cellulose aerogels which are prepared from freeze-drying aqueous cellulose solutions with a layer of silica shell and then hydrophobizing the surface by reacting with vaporized methyltrimethoxylsilane. With the cellulose content in the aqueous solution increases from 0.5% to 1.25%, the density of the cellulose/SiO2 aerogel increases from 28.92 mg/cm3 to 34.83 mg/cm3, and the porosity decreases from 90.2% to 84.48%. The structure and composition of cellulose/SiO2 aerogel are analyzed with SEM, FT-IR, XPS, and TGA. The surface wettability investigation indicates that the prepared cellulose/SiO2 aerogels have excellent hydrophobicity and oleophilicity, with a water contact angle up to 143° and an oil contact angle down to 0°. The results of oil absorption experiments show that the absorption capacity of the aerogels for oils and organic solvents is 16∼40 times their own mass. In addition, as the aerogels are hydrophobic/oleophilic, they demonstrate good oil-selective absorption performance in oil/water mixture. Moreover, experimental results in oil absorption under high temperature conditions and acidic/basic conditions indicate that the aerogels have exceptional resilience towards arduous conditions. These advantages render them a viable option for remediation of water pollution resulted from oil contamination.