Conversion of chitosan and biomass fiber into recyclable superhydrophobic aerogel for efficient oil/water separation through a facile and green approach

Developing high performance and recyclable sorbent through a facile, low-cost, and eco-friendly way is quite important for oily wastewater treatment. Among the various fabrication approaches developed so far, the one using biomass waste as starting materials is particularly attractive in view of the cost and environmental benignity. Herein, a magnetic chitosan/typha orientalis fibers aerogel (MCS/TOFs) with excellent elasticity and superhydrophobicity was facilely prepared through freeze-drying and subsequent low-temperature annealing of biomass fibers (typha orientalis fibers, TOFs), chitosan (CS), and Fe3O4 nanoparticles. Benefiting from the 3D interconnected porous structure, superhydrophobic-lipophilic surface, and capillary effect of TOFs, the MCS/TOFs aerogel exhibited excellent sorption performance including fast sorption speed (few second to achieve saturation), high sorption capacity (up to 88.4 g/g), large flux (2.2 × 104 L·m−2·h−1), and high separation efficiency (98.4 %). Additionally, the MCS/TOFs aerogel can be facilely separated from the solution phase by a magnet at the end of the sorption process. After removal of the adsorbate by extrusion, the recovered MCS/TOFs can be used for next separation cycle, delivering high sorption capacity retention (> 91 % of the initial capacity) after ten sorption-extrusion cycles. This work provides a facile biomass-based approach to high-performance and recyclable sorbent for oily wastewater treatment, exhibiting great potential in practical applications.