Development of a modified composite structure from polyurethane sponge for desalinating seawater polluted by oil

With an increasingly prominent lack of clean water resources, solar water evaporation as a convenient desalination technique has been favored in arid areas, but the serious pollution of offshore oil put forward the higher requirements to desalinate seawater polluted by oil. In this work, a modified composite structure (MCS) with photothermal conversion and water-oil separation properties was developed by modifying polyurethane sponges (PUS) with different hydrophobicity, where its evaporation structure (ES) had excellent light absorbing ability (spectral absorption of 98.1%) and underwater super-oleophobicity (underwater oil contact angel of 151.7°) by loading carbon black (CB) and hydrophilic modification, as well as its oil-absorption structure (OS) can absorb 1 mL oil within 10 s for achieving water-oil separation through hydrophobic modification. The experimental results revealed that the evaporation rate of the evaporator with the MCS reached 2.03 kg m−2 h−1 under 1 sun when its height exposed to air was 3 cm. Consequently, the MCS possessed highly efficient evaporation performance and can effectively desalinate seawater polluted by oil to prevent secondary pollution caused by oil evaporation, which had good practical value and promotion prospects in seawater desalination.