Designing a single superabsorbent for separating oil from both layered as well as micron/submicron size emulsified oil/water mixtures by gamma radiation assisted grafting

Abstract

Separation of oil–water from either its layered mixtures or emulsions is an extremely important challenge in this modern era. Commercially available polyurethane (PU) sponge does not have selectivity towards liquid. In this article, we introduce a rapid, single step, scalable, economic and sustainable route to introduce super selectivity towards oily liquid to the sponge upon modification via gamma radiation assisted grafting of a low surface energy molecule (dodecyl 2-methacrylate). The covalent bond formed through grafting process, provides a highly durable special wettable property (superhydrophobicity and superoleophilicity) to the material without compromising its inherent mechanical property. We demonstrate that single the ‘super’-oil-absorbent (modified PU sponge) is highly efficient to separate quickly both layered oil–water mixtures and emulsions (micron and submicron size), which is unprecedented in the literature. Here, the reported material provides an energy efficient and more convenient approach to separate oil–water from both layered and emulsified oil/water mixture. SEM image indicates the formation of a rough surface on a modified PU sponge with some micron, submicron and nanosize hemispheres or bumps (ups and downs) due to the gamma-radiation based grafting of DMA, which is the cause behind this transformation. Moreover, the same piece of this modified PU sponge can be repetitively used in separation of oil–water for more than 100 times at least without compromising its mechanical & physical (special wetting) properties.