Optimization of magnetic nanostructured materials for cyanotoxin removal by oxidation and regeneration methods

Frequency of cyanobacterial blooms has increased significantly, degrading drinking water quality and exposing humans and animals to toxins such as microcystin-LR (MC-LR), cylindrospermopsin, and anatoxin-A. Previously, we selected nanostructured magnetic composites of mesoporous carbon and activated carbon among thirteen materials for the removal of these toxins by adsorption. This work explores methods for enhancing these composites performance, and assesses their removal efficiency in natural water samples and their toxicity using in vivo models. Oxidation of P-Mes with H₂O₂ improved the adsorption capacity for MC-LR, achieving nearly complete removal from aqueous solution. Moreover, both particle types maintained high adsorption efficiencies, greater than 80 %, over 7 months, at pH values within the range of natural waters, at temperatures from 20 - 30 °C and in samples collected from drinking water treatment plants and reservoirs. However, MC-LR adsorption decreased when particles were tested with high cyanobacterial density lysates. The particles were reusable for nine cycles after regeneration with 75 % acetonitrile, without compromising their adsorption capacity. Finally, no signs of toxicity were detected in plants, zebrafish embryos or mice. With high adsorption efficiency, reusability and a proven lack of toxicity, this technology offers a sustainable strategy for safeguarding water quality in diverse environmental scenarios.