Surface-engineered sponges for recovery of crude oil microdroplets from wastewater


In the United States, the oil industry produces over 15 billion barrels of wastewater contaminated with crude oil microdroplets annually. Current methods are ineffective for the removal of these microdroplets at the variable pH conditions commonly found in wastewater. Here, an innovative surface-engineered sponge (SEnS) that synergistically combines surface chemistry, charge and roughness, provides a solution to this problem. Over broad pH conditions, the SEnS rapidly adsorbed oil microdroplets with 95–99% removal efficiency, predominantly facilitated by Lifshitz–van der Waals forces. At the optimum pH, 92% of the oil was adsorbed within 10 min. The oil was subsequently recovered by solvent extraction under ambient conditions, and the cleaned SEnS was reused for oil microdroplets adsorption ten times. The combined efficacy and reusability can enable large-scale removal and recovery of crude oil microdroplets from wastewater.

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Fig. 1: The rationale behind the design of SEnS for oil microdroplets adsorption.
Fig. 2: SEnS surface physicochemical properties.
Fig. 3: SEnS surface roughness and wetting properties.
Fig. 4: Prediction and validation of crude oil adsorption based on material properties.
Fig. 5: SEnS regeneration, reuse and oil recovery.

Data availability

The data used in the current manuscript are available from C.B.P. upon reasonable request.

Change history

  • 13 January 2020

    An amendment to this paper has been published and can be accessed via a link at the top of the paper.


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We thank S. Shah and R. Pini for providing access to the X-ray microCT instrument and image analysis, and J. P. M. Trusler for the tensiometer at the Chemical Engineering Department, Imperial College London. We also thank L. Fiddes for confocal and AFM imaging, A. Stammitti Scarpone for crude oil interfacial tension measurement, A. Kondor and J. Acs for surface energy measurements and T. Luxbacher of Anton–Paar for zeta potential measurements. We also thank Y. Lu for artistic contribution to Fig. 1a,b. P.C. appreciates a Bert Wasmund Graduate Fellowship in Sustainable Energy Research, Queen Elizabeth II/Herbert A. Staneland Graduate Scholarship in Science and Technology, William Dubar Memorial Scholarship in Mechanical Engineering, and Ontario Graduate Scholarship. The research work was supported by the Natural Sciences and Engineering Research Council of Canada (grant no. NSERC DG 154279-2010), Consortium of Cellular and Microcellular Plastics and Natural Resources Canada Oil Spill Response Program (grant no. OSRS2-011), Department of Fisheries and Oceans (grant no. MECTS-3955465), Natural Sciences and Engineering Research Council of Canada Discovery Grant, Engineering and Physical Sciences Research Council, UK, and National Natural Science Foundation of China (grant no. 51902287).

Author information

P.C. designed an interdisciplinary research plan and coordinated the project. P.C., W.S., D.R.W., G.A.O. and C.B.P. designed and analysed materials, P.C. and D.R.W. designed and analysed chemical processes, P.C. and A.M.B. designed and analysed water quality studies. P.C., W.S. and A.P.Y.W. performed experiments. P.C. drafted the manuscript. A.M.B. and C.B.P. edited the manuscript. All authors critically reviewed and approved the final manuscript.

Correspondence to Geoffrey A. Ozin or Amy M. Bilton or Chul B. Park.

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Competing interests

Based on the datasets used in the manuscript, a patent application has been filed (British Provisional Patent Application no. GB 1905680.3).

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Supplementary Information

Supplementary Figs. 1–8, Discussion, Tables 1 and 2 and refs. 1 and 2.

Supplementary Video

The three-dimensional view of the SEnS, obtained using in-situ micro-CT, shows the adsorbed oil droplets spread on the pore surface and remain trapped inside. The images are not to scale.

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Cherukupally, P., Sun, W., Wong, A.P.Y. et al. Surface-engineered sponges for recovery of crude oil microdroplets from wastewater. Nat Sustain (2019).

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