Preparation of Halloysite-Based Superhydrophobic Aerogels for Oil-Water Separation

The frequent occurrence of oil spill accidents and the massive discharge of oily wastewater have become serious environmental pollution problems. Herein, we report a facile and easy method for fabricating superhydrophobic halloysite-based aerogels (PDMS@HNCS) through mixing halloysite and chitosan without cross-linking agents. The as-prepared aerogel with an aligned tubular channel structure has low density (41.98-52.83 mg cm(-3)) and robust mechanical properties because of the directional freezing and freeze-drying method. The dip-coating method and heat treatment of the halloysite-based aerogels with PDMS endow them with superhydrophobic properties, which is beneficial for selective adsorption and separation of oil-water mixtures, and the contact angle with water of PDMS@HNCS aerogels can reach 151.4 degrees. The adsorption capacity of the aerogel for various oils or organic solvents is 10.13-22.61 g g(-1). Besides, the aerogel can separate various water-in-oil emulsions with high separation efficiencies of up to 99.90%. Overall, clay-based aerogels have gradually attracted attention in the field of oil-water separation owing to their low density, good absorption properties, and biocompatibility, and this work may develop a new approach to fabricating materials for efficient oil-water separation by using a simple method and low-cost materials.