Membrane Distillation Processes for Water Treatment and Desalination

Membrane distillation (MD) is a thermally driven separation technique that exploits a hydrophobic, microporous membrane to transfer water vapour from a heated saline or contaminated feed to a cooler permeate side. The driving force is the vapour pressure difference created by a temperature gradient across the membrane. Unlike pressure-driven methods, MD operates at near-ambient pressures and can utilise low-grade heat sources such as industrial waste heat or solar thermal energy. Several configurations—direct contact, air-gap, vacuum and sweep-gas—have been explored to optimise heat recovery and minimise conductive losses. Key advantages include complete rejection of non-volatile solutes, tolerance of high salinity or fouling feeds, and integration with renewable energy. Nevertheless, the technology faces challenges in managing temperature and concentration polarisation, membrane wetting and fouling, and in achieving large-scale cost-effective modules. Recent innovations focus on advanced membrane materials and module designs that enhance vapour flux, improve anti-wetting robustness and enable energy-efficient coupling with solar or photothermal systems. With water scarcity and energy-water-environment synergies rising on the global agenda, MD offers a versatile, decentralised approach to produce high-quality freshwater from seawater, industrial effluents and agricultural run-off, while facilitating resource recovery from brines.

Research from Nature Portfolio

Recent studies have demonstrated the design of hierarchical porous membranes that reconcile conflicting requirements of pore size and wetting resistance. By grafting nanofilament networks onto commercial micro-porous substrates, researchers achieved super liquid-repellent surfaces that sustain high hydrostatic pressures without pore intrusion, leading to up to 60 % higher vapour flux than conventional membranes while maintaining salt rejection and long-term stability. Another advance employs two-dimensional Ti3C2Tx MXene nanosheets integrated within polymer matrices to realise photothermal membrane distillation. Under one-sun irradiation, these membranes locally convert light into heat at the membrane–feed interface, maintaining a stable temperature gradient and suppressing fouling and scaling. The resulting system delivers a marked increase in freshwater production rate and energy efficiency, illustrating a promising route to solar-driven desalination with minimal thermal losses.

Membrane Distillation Processes for Water Treatment and Desalination publication trend

The graph below shows the total number of articles in membrane distillation processes for water treatment and desalination across all publications each year (not limited to Nature Index journals).

Technical terms

Membrane distillation: A thermal separation process in which only vapour passes through a hydrophobic, microporous membrane driven by a vapour pressure differential.

Hydrophobic membrane: A membrane surface that repels liquid water, preventing feed solution from entering pores while allowing vapour transport.

Superhydrophobicity: A surface property characterised by very high water contact angles (>150°) imparting extreme water-repellence and anti-wetting behaviour.

Photothermal effect: Conversion of light energy into heat by photothermal materials, used to locally raise temperature and drive vapour flux in MD.

Fouling: Deposition or accumulation of organic, inorganic or biological substances on membrane surfaces or within pores, leading to flux decline.

Temperature polarisation: A phenomenon in MD where the temperature at the feed–membrane interface is lower than the bulk feed temperature, reducing the effective vapour pressure difference.

References

1. Advancements in Nanoenabled Membrane Distillation for a Sustainable Water‐Energy‐Environment Nexus. Advanced Materials (2023).
2. A super liquid-repellent hierarchical porous membrane for enhanced membrane distillation. Nature Communications (2023).
3. Transforming Ti3C2Tx MXene’s intrinsic hydrophilicity into superhydrophobicity for efficient photothermal membrane desalination. Nature Communications (2022).
4. The advent of thermoplasmonic membrane distillation. Chemical Society Reviews (2022).
5. Fouling mitigation strategies for different foulants in membrane distillation. Chemical Engineering and Processing - Process Intensification (2021).