DYNA JOURNAL ENGINEERING

The new technology is based on a composite gel known as MMS, built from a sodium alginate matrix incorporating MXene nanosheets and magnesium oxide (MgO) nanoparticles. MXene acts as a highly efficient photothermal material, absorbing sunlight and converting it into heat, while MgO serves as a selective boron adsorbent within the gel’s porous structure.

Under standard solar illumination, laboratory tests showed that the MMS material achieved an evaporation rate of 2.14 kilograms of water per square meter per hour, while simultaneously adsorbing 225.52 milligrams of boron per square meter within nine hours of continuous operation. These results demonstrate that MMS can both desalinate seawater and significantly reduce boron concentration in a single integrated step, overcoming a key limitation of conventional reverse osmosis systems, which struggle to remove boron effectively.

The researchers, led by Fan Zhimin, emphasize that the design leverages synergistic temperature, concentration and flow fields within the gel to accelerate boron adsorption kinetics. The hierarchically porous architecture of the material enhances water transport and provides a large internal surface area for light absorption and ion interaction, maintaining high performance over multiple use and regeneration cycles.

Outdoor field tests were carried out in Hong Kong, where MMS-based modules produced 5.20 kilograms of freshwater per square meter per day and recovered 122.45 milligrams of boron per square meter. In these real-world trials, no boron was detected in the condensed water, confirming the system’s ability to meet both drinking-water requirements and boron-removal objectives at the same time.

Beyond desalination, the team showed that the harvested boron can be reused as a micronutrient in agriculture, increasing the seed germination rate of Brassica juncea by about 13% and roughly tripling biomass compared with boron-deficient control soils under controlled conditions. This points to integrated solutions for coastal regions suffering from freshwater scarcity and micronutrient-poor soils, linking water security with more efficient management of critical mineral resources.

The authors stress that key questions remain regarding large-scale cost, long-term durability and the integration of these modules into existing desalination infrastructure. However, in a context of growing global competition for strategic minerals such as boron and rising concern over the environmental impacts of desalination, this solar-driven multi-field strategy based on composite gels stands out as a promising route toward more sustainable and autonomous systems.

Main scientific source (PubMed article):
Solar-driven multi-field synergistic strategy for integrated freshwater production and boron harvesting – Science Bulletin, via PubMed: https://pubmed.ncbi.nlm.nih.gov/41353087/