Nanotechnology for oil-water separation

The contamination of oceanic and ground water sources due to oil seepages and industrial waste solvents has emerged as a global issue urging for immediate counter measures to epitomize the catastrophic repercussions on sensitive ecological system. In this sense, various advanced techniques have been explored for the effective oil/solvent-water separation. Recently, researchers have focused on nanomaterials for efficient oil/solvent-water separation, as they render highly active surface area, improved functionality with ability to tailor the properties, and nano-scale dispersion. The oil/solvent-water separation is widely achieved via superwetting phenomena, i.e., superhydrophobic/superhydrophilic, superoleophobic/superoleophilic, which leverages selective wettability towards oil/solvents or water. The superwetting materials can be fabricated by engineering the porous surface-architecture and nano/micro-scaled hierarchical surface roughness. Various nano-functionalized superwetting materials like Janus fabrics, membranes, nanofibers, sponges/foams, and meshes have been explored for the treatment of oil/solvent-water emulsions, as they render high separation efficiency, recyclability, mechanical durability, and high performance against harsh environments. These superwetting nano-engineered materials are promising potential candidates for treating oil/solvent-water emulsions in large quantities, as compared to traditional separation techniques in the near future. In this book chapter, we have discussed the recent advances on superwetting nano-engineered Janus materials, foams, and sponges for the efficient oil/solvent-water separation, along with the governing principle theories such as Wenzel, and Cassie-Baxter. We have also discussed the fabrication methods for these materials, followed by a summary and future scope.