Top-Down Preparation of Sustainable Corn Stalk Pith-Based Hydrophobic Aerogel for Efficient Oil Sorption

Abstract

Bio-based aerogel has become an attractive sorbent for spilled oil and organic pollutants because of its light weight, high porosity and strong sorption capacity. However, the major challenge is that the current construction process is mainly "bottom-up" technology, which is process-complex, time-consuming, and energy-intensive. Herein, we report a green, efficient and selective sorbent prepared from corn stalk pith (CSP) in site using the deep eutectic solvent (DES) treatment, followed by TEMPO/NaClO/NaClO2 oxidization and microfibrillation, and then hexamethyldisilazane hydrophobic coating. Such chemical treatments selectively remove lignin and hemicellulose, break the thin cell walls of natural CSP, forming an aligned porous structure with capillary channels. The resultant aerogels had a density of 29.3 mg/g, a porosity of 98.13%, and a water contact angle of 130.5◦, exhibiting excellent oil/solvents sorption performance, with a high sorption capacity in the range of 25.4–36.5 g/g, approximately 5–16-fold higher than CSP, and with fast absorption rate and good reusability. Due to the utilization of eco-friendly and green DES, the novel oil sorbent can be mass produced by utilizing CSP wastes via a top-down approach. This simple, low-cost and sustainable method has great potential for developing efficient sorbents for oil-water separation.

Keywords: Corn stalk pith, Top-down approach, Hydrophobic aerogel, Adsorption, Deep eutectic solvent