Hydrophobic and magnetic fabrication of hydroxyethyl cellulose-lignin aerogel through ultrasound enhancement for efficient oil/water separation

Oil leakage has caused great damage to the marine aquatic environment. Cellulose aerogels can be used to separate oil/water mixture, but the low strength and recyclability have restricted its application. In order to improve the performance of cellulose-based aerogels, hydrophobic and magnetic modification with ultrasound enhancement was carried out. Firstly, hydroxyethyl cellulose-lignin aerogel (CL-aerogel) was synthesized by combining hydroxyethyl cellulose with lignin through sol–gel method with freeze-drying. The incorporation of lignin endowed the aerogel with a 3D porous network and enhanced mechanical properties. Then CL-aerogel was modified with n-dodecyl mercaptan (NDM) and Fe3O4 NPs through ultrasound enhancement to obtain HMCL-aerogel. The results disclosed that with the increase in NDM usage and ultrasound time, the hydrophobicity and magnetic responsiveness of aerogel was enhanced. Furthermore, HMCL-aerogel had good oil absorption capacity with high selectivity. The HMCL-aerogel could be easily recycled by an external magnetic field and could be reused through a simple extrusion treatment. Meanwhile, the aerogel exhibited effective separation of oil/water mixture with a flux as high as 2986 L‧m−2‧h−1 even in corrosive conditions and maintained over 99 % separation efficiency after 10 separation cycles. Therefore, the hydrophobic and magnetic hydroxyethyl cellulose-lignin aerogel could potentially serve as an intriguing candidate for practical oil-polluted wastewater remediation.