Superhydrophobic and oleophilic polyurethane sponge for oil/water separation

Massive oil spills and the discharge of oily wastewater not only inflict permanent damage upon ecosystems but also pose a significant threat to human health. Developing a low-cost functional material for efficient oil-water separation of multi-type of oil-water mixtures, such as free oil, dispersed oil, and emulsion oil, has always been a difficult challenge. In this work, the rough structure was successfully constructed by etching the surface of polyurethane (PU) sponges with sodium fluoride (NaF) aqueous solution. The introduction of hydroxyl-terminated fluorosilicone oil (HTFO) with hydrophobicity on the surface of PU sponge was followed by using glycidyl methacrylate (GMA) as the "bridge". The modified PU (RSS-PU) sponge had a contact angle of 151 ± 2° for water and 0 ° for oil. In addition, the RSS-PU sponge also demonstrated excellence oil sorption ability, its sorption of vegetable oils reached 47.90 g/g, for organic solvents the highest 72.06 g/g, maintaining its oil-absorbing capacity over multiple cycles. Impressively, the superhydrophobic/superoleophilic properties of the RSS-PU sponge has good durability and chemical stability. Meanwhile the superhydrophobic/superoleophilic characteristics of the RSS-PU sponge enable to effectively separate oil-water mixtures, and achieve separation efficiencies of 94.13% and 82.74% for toluene and water mixture without and with surfactants for emulsifying.