Superhydrophobic lignin-based multifunctional polyurethane foam with SiO2 nanoparticles for efficient oil adsorption and separation

Superhydrophobic polyurethane foam is one of the most promising materials for oil-water separation. However, there are only limited studies prepared matrix superhydrophobic foams as adsorbents. In this paper, SiO2 modified by 1H, 1H, 2H, 2H-perfluorododecyl trichlorosilane (F-SiO2) was added into the lignin-based foam matrix by a one-step foaming technique. The average diameter of F-SiO2 was about 480 nm with an water contact angle (WCA) of 160.3 degrees. The lignin-based polyurethane foam with F-SiO2 had a superhydrophobic water contact angle of 151.3 degrees. There is no obvious change in contact angle after 100 cycles of compression or after cutting and abrasion. Scanning electron microscopy (SEM) analysis showed that F-SiO2 was distributed both on the surface and inside of the foam. The efficiency for oil-water separation reached 99 %. Under the light intensity of 1 kW/m2, the surface temperature of the lignin-based foam rose to 77.6 degrees C. In addition, the foam exhibited self-cleaning properties and degraded within 2 h in an alcoholic alkali solution. Thus, in this study, we developed a novel matrix superhydrophobic lignin-based polyurethane foam with an excellent promise to be used as oil water separation adsorbents in industrial wastewater treatment and oil spill clean-up processes.