Imagine a world where clean, fresh water is accessible to everyone, even in regions facing severe water scarcity. Researchers at Universiti Teknologi Malaysia (UTM) are bringing this vision closer to reality with a groundbreaking innovation in passive solar desalination technology.

Solar desalination offers a low-cost, environmentally friendly way to produce fresh water from saline sources. Traditional solar desalinators often rely on wicking structures to evaporate water efficiently. However, these structures struggle with continuous salt rejection, limiting their operational time. The UTM team has tackled this challenge head-on by designing an inverted single-stage solar membrane desalinator. This innovative design enables continuous desalination and salt rejection, paving the way for more sustainable and reliable water production.

The key to this breakthrough lies in the desalinator’s unique architecture. Saltwater flows over a radiative-absorbing, porous, hydrophobic evaporator membrane, allowing salt to continuously diffuse away. Simultaneously, the heated water vapor travels to a cooler microporous membrane below, where it condenses into fresh water. This design incorporates thin-film condensation on a microporous membrane, enhancing heat transfer during condensation. Furthermore, by condensing within the microporous membrane, the distance between the condenser and evaporator is minimized, thus reducing vapor transport resistance.

The UTM team demonstrated a record-breaking continuous desalination and salt rejection test duration of 7 days under simulated sunlight. Even with increased heat loss necessary for salt rejection, the desalinator achieved a water collection rate of 0.487 kg per square meter per hour, corresponding to an impressive 32.2% solar-to-water efficiency. This work represents a significant leap forward in the robustness of solar desalinators.

This advancement holds immense promise for communities struggling with water scarcity. The next steps involve further optimizing the design and exploring potential applications in diverse environments. This research from UTM not only offers a sustainable solution for fresh water production but also opens up new avenues for innovation in passive solar desalination technology. https://doi.org/10.1016/j.jece.2025.116667