Oil Recovery from Nanoporous Media via Water Condensation

Abstract

Oil–nanoporous materials interplay is ubiquitous in oil recovery from unconventional reservoirs, environmental clean‐up, and membrane technology, so there is a genuine need for novel approaches that can monitor, manipulate, and also extract the oil present in nanoporous media. Here demonstrated is a water condensation–assisted method of extracting oil from nanopores. Under cooling‐induced condensation at room conditions, distinctive droplet modes act as both decoupling and collecting elements to transport oil from the pore space toward the nanomaterial surface after water evaporation. Even the movement of the oil through the nanoporous network can be visualized by taking advantage of the interference response of visible light in a nanoporous thin‐film platform. The method and results presented in this work open different routes to exploit oil–water–nanopore interactions and enable novel perspectives for oil recovery and environmental clean‐up.

How water wets and self-hydrophilizes nanopatterns of physisorbed hydrocarbons

“…This observation is of particular relevance for interface-dominated structures and thus for processes in nanoporous media or at nanostructured surfaces, where the hydrocarbon displacement mechanism explored here at planar surfaces acts like a self-cleaning mechanism and could substantially alter self-diffusion dynamics [71] and hydraulic permeabilities [22,72,4,13,23] upon water transport and phase transitions [19]. Specifically for capillarity-driven, spontaneous imbibition, it also means that by water wetting a quite effective displacement of hydrocarbons should be possible, in agreement with recently reported experiments on water-condensation induced oil-displacement in mesoporous silicas [73].…”

How water wets and self-hydrophilizes nanopatterns of physisorbed hydrocarbons

“…This observation is of particular relevance for interface-dominated structures and thus for processes in nanoporous media or at nanostructured surfaces, where the hydrocarbon displacement mechanism explored here at planar surfaces acts like a self-cleaning mechanism and could substantially alter self-diffusion dynamics [71] and hydraulic permeabilities [22,72,4,13,23] upon water transport and phase transitions [19]. Specifically for capillarity-driven, spontaneous imbibition, it also means that by water wetting a quite effective displacement of hydrocarbons should be possible, in agreement with recently reported experiments on water-condensation induced oil-displacement in mesoporous silicas [73].…”

Nanopore-Mediated Spontaneous Dilution of Droplets: When Evaporation Turns to a Dilutor

“…8,9 The fluid-filled pore region around the drop (annulus) can be clearly observed by optical microscopy because it produces a refractive index contrast in relation to the empty pores outside the annular region. 10 In order to evaluate the ability of the solute extracting from the bulk droplet via the spontaneous capillary flow across the nanopores that is induced by evaporation in the drop periphery, we performed comparative experiments by evaporating 1.0 μL KCl solutions (0.4−2 mM) on nanoporous and non-nanoporous thin films (i.e., deposited from solutions not containing the templatedense thin films, named DTFs) under controlled ambient conditions (24 °C temperature 40% humidity). Since the contact angles for both surfaces were identical (∼32°), drops of the same size are formed.…”

“…Nanoporous thin films were produced using the versatile method of sol–gel combined with supramolecular self-assembly by dip coating of silicon substrates (see the Experimental Section for details). , This led to the formation of thin nanoporous films (170 nm thick), displaying a high porous volume (47%) with well-defined pore and neck diameters of 9 and 5.5 nm, respectively, as evidenced by electron microscopy and environmental ellipsometric porosimetry analysis (see Figure a–c). When drops of aqueous KCl solutions were placed on the surface covered by these nanoporous thin films (hereafter labeled as NTFs), they remained pinned, accompanied by the formation of a wetted peripheral steady-state annulus during their evaporation (see Figures d and a). , The fluid-filled pore region around the drop (annulus) can be clearly observed by optical microscopy because it produces a refractive index contrast in relation to the empty pores outside the annular region …”