Polymer-derived Si3N4 nanofelts as a novel oil spills clean-up architecture

Oil spills clean-up and oil-water separation is a research topic of increasing relevance because of the wide diffusion of the off-shore oil industry. Herein, we developed a new hydrophobic (contact angle up to 143°) / oleophilic Si3N4 nanofelt by controlled pyrolysis of a pre-ceramic polymer foam. The material is proven to selectively absorb pump oil and separate it from water. Weight gain always larger than 500 % (up to 2500 %) were measured after oil impregnation and more than 90 % of the geometrical volume of the felts was filled by oil. The material can be easily cleaned by thermal treatment in air. The stability of the Si3N4 nanofelt depends on the geometrical architecture of the pre-ceramic sponge; in particular, samples developed from small-pores foams (90 pores per inch) are extremely stable with no degradation of their properties in the first six impregnation /cleaning cycles.