Oil Sequestration in Synthetic Trees with Nanoporous Leaves and Oleophilic Roots

For systems containing oil–water mixtures, such as oil spills, contaminated groundwater, various industrial processes, etc., it is often desirable to selectively capture the oil phase. Here, we demonstrate transpiration-powered oil sequestration in a synthetic tree when its roots are placed in an oil–water bath. As water transpired from the nanoporous synthetic leaf, driven by the negative Laplace pressure of concave menisci within the nanopores, oil preferentially entered the tree via membranes that were oleophilic and hydrophobic. Both filtration and the subsequent pumping against gravity of oil up the tree’s vertical tube array were spontaneously powered by transpiration. After the tree’s precharged water was fully evaporated, liquid samples extracted from the tree were ≈96–100% pure oil as measured from refractometry and gravimetry.