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°. 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.