Cyanobacterial blooms are increasingly common in freshwater ecosystems due to eutrophication and climate change, raising serious concerns about water safety. Among the various cyanotoxins produced by genera like Microcystis, Anabaena, and Planktothrix, microcystins (MCs)—especially microcystin-LR (MC-LR)—stand out for their high toxicity and persistence. As hepatotoxins, MCs pose significant health risks, prompting the World Health Organization to set a maximum allowable level of 1 µg/L for MC-LR in drinking water. This has created a pressing need for cost-effective and sustainable monitoring and remediation strategies.
Traditionally, water treatment and analysis rely on solid-phase extraction (SPE) using disposable C18 cartridges, which come with economic and environmental costs. In this context, the present study explores the use of zeolite-rich geomaterials (ZG) as alternative adsorbents for MC-LR removal from water. Zeolites are hydrated aluminosilicates with high cation exchange capacity and an open framework structure, making them attractive for environmental remediation. These minerals occur naturally in volcanic regions such as Central-Southern Italy, where quarrying for dimension stones generates zeolite-rich waste materials that retain the original mineralogical properties, offering a low-cost secondary resource aligned with circular economy principles.
Preliminary experiments tested the adsorption capacity of ZG materials by incubating them with MC-LR-spiked water. Post-incubation, both the solid and aqueous phases were extracted and analyzed using liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS). The study assessed the impact of several variables: mineralogical composition, particle size, thermal activation, and sequential exposure time. While initial removal efficiency was moderate, sequential treatments enhanced MC-LR adsorption, indicating that repeated contact improves performance.
These findings support the potential of zeolite-rich geomaterials in mitigating cyanotoxins and lay the groundwork for further research aimed at optimizing material properties, exploring surface modifications, and testing real-world applications for water treatment.
