Sugarcane-based superhydrophilic and underwater superoleophobic membrane for efficient oil-in-water emulsions separation

The development of ecological, low cost, easy preparation, especially high performance materials for emulsions separation is of great importance due to the rise in pollution of oil-water emulsions from industrial production and domestic waste. Straws as agricultural wastes, including plenty of hydrophilic groups and multi-level pore structures, can be prepared as biomass membranes for oil-water emulsion separation. Herein, a novel super-hydrophilic sugarcane-based (SHS) membrane was prepared using a facile and eco-friendly method including chemical treatment and freeze-drying. The as-prepared SHS membrane has unique wettabilities due to the hydrophilic property of the internal cellulose and the micro-nano pores, including superhydrophilicity (water contact angle of 0°) and underwater superoleophobicity (underwater oil contact angles of over 150°). The SHS membrane has good durability and stability against ultraviolet (UV) irradiation, corrosion by acids and alkalis, mechanical abrasion and especially mould adhesion. Importantly, the SHS membrane can be used for separation of various oil-in-water emulsions, and exhibits excellent separation performances such as high separation efficiency (> 99 %) and good separation flux (above 891 L m-2 h-1 bar-1). The SHS membrane also exhibits excellent recyclability over 10 continuous separation cycles. Furthermore, the SHS membrane can be utilized to selectively absorb water from oils as a water absorbent material. Hence, SHS membrane is a promising and practical material for applications in treatment of wastewater containing oil-water emulsions.