The Solar2Clean project, a FCT funded project on sustainable water purification technologies powered by solar energy, was successfully completed earlier this year.
Led by Professors Ana Clara Marques and Susete Martins-Dias, researchers at CERENA, the project has made significant progress in developing water treatment solutions using solar energy. The project brought together a multidisciplinary team from Instituto Superior Técnico and international partners, including ETH Zurich, integrating expertise in materials science and environmental engineering.
At the heart of Solar2Clean is photocatalysis, a process in which solar light activates materials capable of decomposing harmful pollutants—such as antibiotics, dyes, and microplastics—into non-toxic by-products. While this method has shown strong potential in laboratory settings, its practical application in real-world environments remains complex. To overcome these challenges, the project focused on innovations in material development and reactor design.
One of the project’s major scientific achievements was the successful degradation of antibiotics in wastewater, a growing concern due to their persistence and contribution to antimicrobial resistance. This issue is particularly relevant in Portugal, where pharmaceutical industries are actively seeking effective solutions to remove antibiotic residues from their effluents before discharge into municipal systems.
To address the limitations of conventional photocatalysts—often nanoscale particles that are difficult to recover and may pose environmental risks—the team developed MICROSCAFS®: silica-based microspheres with coral-like porosity that serve as scaffolds for photocatalytic nanoparticles. These structures improve handling, recyclability, and can incorporate titanium dioxide, making them inherently active. In collaboration with Ca’ Foscari University of Venice, the team also developed a sustainable synthesis route using rice husk-derived silica, promoting circularity through waste valorization.
Another key innovation was the engineering of doped photocatalysts capable of absorbing visible and infrared light and converting it into UV light (which represents only 5% of the total solar radiation), enhancing solar efficiency. Additionally, the project demonstrated that combining gamma irradiation with photocatalysis can render microplastics like polyethylene biodegradable, supporting continuous operation and expanding the practical applicability of the technology in industrial wastewater treatment.
Solar2Clean reflects CERENA’s commitment to sustainable, interdisciplinary research in environmental engineering. As a next step, the team is exploring opportunities to scale up the technology to a pilot scale reactor, and collaborate with industry partners to bring these solutions closer to real-world implementation.