Facile preparation of CuS microspheres-based superhydrophobic paper with self-cleaning, high chemical stability, and photothermal effect enhanced separation of oil/water mixtures and emulsions

Frequent oil spill accidents and the discharge of oily wastewaters cause significant threats to the marine ecological systems and human health. Herein, a CuS microspheres-based superhydrophobic paper (CuS SP) has been prepared with the photothermal property for efficient oil/water separation and emulsions. To increase the durability, polydopamine is introduced to cellulosic fibers of the filter paper via the self-assembly of dopamine. The CuS SP exhibits a water contact angle of 150.5° and an oil contact angle of ~ 0°, displaying excellent superhydrophobicity and superoleophilicity. Also, the CuS SP possesses excellent chemical resistance, thermal stability, mechanical durability, and self-cleaning property. More importantly, the maximum surface temperature of the CuS SP can reach about 54.6 °C after 100 s under one sunlight irradiation (1.0 kW m−2), and it remains at about 54 ℃ even after 10 cyclic tests with light on and off. The separation flux of CCl4 can be increased by about 14.3% under one sunlight irradiation by using the CuS SP when compared with that without sunlight irradiation. Although the photothermal effect has no obvious influence on the separation efficiency, the CuS SP still shows a high separation efficiency (> 99%) for CCl4/water mixture under 15 cyclic separation tests with/without sunlight irradiation. Besides, in situ experimental observations for the separation of oil-in-water emulsions have been investigated with the CuS SP by using an optical microscopy, and the possible mechanisms for the separation of oil-in-water emulsions are discussed. Thus, the as-prepared CuS SP shows great potentials in the fields of self-cleaning, and the separation of oil/water mixtures and emulsions.