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Fractal-inspired ultrapermeable membranes for electricity-free portable nanofiltration

Nature Water volume 4, pages 68–77 (2026) Cite this article

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Abstract

Nanofiltration is an effective technology for producing clean water through the removal of harmful pathogens, micropollutants and ions. However, its dependence on a power supply and complex configuration hinder the deployment of nanofiltration systems in underserved regions. To support universal access to clean water in these regions, we have developed an ultrapermeable polyamide nanofiltration membrane that can be used in an electricity-free portable purifier. The membrane features a nature-inspired substrate that mimics the highly efficient fractal transport structures found in leaves and blood vessels. The polyamide nanofilm supported by this unique fractal substrate achieved a record-high permeance of 113.6 l m−2 h−1 bar−1, an order of magnitude higher than current commercial benchmarks. The design enabled rapid water purification by simple manual vacuum pumping, producing over 250 ml of pure water within 15 min using small palm-sized membrane disks with an area of 157 cm2. Furthermore, the nanofiltration membrane exhibited 98.0% Na2SO4 rejection, along with exceptional removal of pathogens (>99.9999%) and micropollutants (for example, 99.1% of perfluorooctanesulfonate). By delivering high-quality purified water without the need for any electricity, this portable purifier offers a practical solution that is aligned with the United Nations Sustainable Development Goal 6, focusing on clean water and sanitation.

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Fig. 1: Fractal-like substrates for enhancing the water permeance of PA nanofiltration membranes.
The alternative text for this image may have been generated using AI.
Fig. 2: Properties of fractal-like substrates.
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Fig. 3: Morphology and separation performance of nanofiltration membranes.
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Fig. 4: Water purification performance of uPA nanofiltration membranes.
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Fig. 5: Prototype of an electricity-free portable nanofiltration purifier and its purification performance.
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Data availability

All of the data generated in this study are available within the Article and its Supplementary Information. Source data are provided with this paper.

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Acknowledgements

The work was substantially supported by the Research Grants Council of the Hong Kong Special Administration Region, China (SRFS2021-7S04, C.Y.T.).

Author information

Authors and Affiliations

  1. Department of Civil Engineering, The University of Hong Kong, Hong Kong, China

    Bowen Gan, Yaowen Hu, Wenyu Liu, Zhuting Wang, Qimao Gan, Qian Xiao, Lu Elfa Peng & Chuyang Y. Tang

  2. Dow Centre for Sustainable Engineering Innovation, School of Chemical Engineering, The University of Queensland, Brisbane, Queensland, Australia

    Zhe Yang

  3. State Key Laboratory of Advanced Environmental Technology, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, China

    Peng-Fei Sun

Authors
  1. Bowen Gan
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Contributions

B.G., L.E.P. and C.Y.T. conceived the idea and designed the research. B.G., W.L., Z.W. and Y.H. performed the experiments. Z.Y., Q.G., P.-F.S. and Q.X. provided constructive suggestions for the results. B.G., L.E.P. and C.Y.T. contributed to the writing of the manuscript.

Corresponding authors

Correspondence to Lu Elfa Peng or Chuyang Y. Tang.

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Nature Water thanks Xiao-mao Wang and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information (download PDF )

Supplementary Discussion, Methods, Figs. 1–29, Videos 1 and 2, and Table 1.

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Supplementary Video 1 (download MP4 )

The filtration process of the Fr-uPA purifier.

Supplementary Video 2 (download MP4 )

Video showing that the manual pump is easy to operate by hand.

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Gan, B., Hu, Y., Liu, W. et al. Fractal-inspired ultrapermeable membranes for electricity-free portable nanofiltration. Nat Water 4, 68–77 (2026). https://doi.org/10.1038/s44221-025-00551-3

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