In situ self-foaming preparation of hydrophobic polyurethane foams for oil/water separation

Discharge of oily sewage causes serious environmental pollution and waste of resources, which can be solved by the process of oil/water separation. Polyurethane foam is a kind of promising candidate material for oil/water separation. In this work, a series of hydrophobic/lipophilic polyurethane foams were prepared by the in situ self-foaming method. The as-prepared polyurethane foams exhibited abundant open pore structures, excellent stability and superior hydrophobicity/lipophilicity. Thus, the as-prepared polyurethane foams can selectively absorb various oils/organic solvents from static and dynamic oil/water mixtures. The maximum absorption capacity for pump oil was up to 75.0 g g−1, and the separation fluxes were 1.5 × 106 L m−3 h−1 and 3.0 × 105 L m−3 h−1 for layered and turbulent oil/water mixtures, respectively. Moreover, the as-prepared polyurethane foams can separate the oil-in-water emulsions with a separation efficiency of >99% and a separation flux of 2.7 × 105 L m−3 h−1. The large-scale preparation of hydrophobic polyurethane foams by this method confirmed their potential in practical applications.