In situ fastening graphene sheets into a polyurethane sponge for the highly efficient continuous cleanup of oil spills

Oil sorbents are an attractive option for oil-spill cleanup as they may be used for collection and complete removal of oil without adversely affecting the environment. However, traditional oil sorbents exhibit low oil/water separation efficiency and/or low oil-sorption capacity. In this study, an ultra-high performance graphene/polyurethane (PU) sponge has been successfully obtained by in situ polymerization in the presence of graphene dispersed in N-methylpyrrolidone (NMP). During polymerization, the NMP/graphene dispersion not only serves as a weak amine catalyst for the formation of the sponge, but promotes fixation of the graphene sheets in the framework of the PU sponge owing to the strong dipole interaction between NMP and graphene. The as-prepared graphene/PU sponge was used as an absorbing material for the continuous removal of oil from oil-spill water. The graphene/PU sponge can continuously and rapidly remove oils from immiscible oil/water mixtures in corrosive solutions, including strong acids and bases, hot water, and ice water, with an excellent separation efficiency of above 99.99%. In addition, the as-prepared graphene/PU sponge was effective in separating surfactant-stabilized emulsions with a high separation efficiency of > 99.91%.