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Cyanotoxin Removal from Water Using Activated Carbon Magnetic Beads  †

Departamento de Farmacología, Farmacia y Tecnología Farmacéutica, Facultad de Veterinaria, Universidad de Santiago de Compostela, 27002 Lugo, Spain
Departamento de Física Aplicada, Facultad de Física, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
Authors to whom correspondence should be addressed.
Presented at the 7th Iberian Congress on Cyanotoxins/3rd Iberoamerican Congress on Cyanotoxins, Ponta Delgada, Portugal, 18–20 July 2022.
Presenting author (poster).
Biol. Life Sci. Forum 2022, 14(1), 16;
Published: 19 July 2022


There are many contaminants in water that may damage the health of people and animals, such as naturally occurring cyanotoxins, which have increased their presence in recent years due to climate change and eutrophication. Although water must pass through a treatment station before consumption, none of the treatment methods used are totally effective for the elimination of cyanotoxins. In this study, a complementary method for toxin removal is investigated which consists of using nanostructured beads with a magnetic core coated by an adsorption material. In contact with water, the beads are capable of adsorbing different toxic compounds on their surface and can be easily separated from water, afterwards, by a magnet. Adsorption spheres are prepared with nanostructured magnetite cores coated with activated carbon using sodium alginate as an agglutinating compound. The adsorption capacity of these magnetic beads is assessed with water solutions of microcystin-LR, cylindrospermopsin, and anatoxin-A. Toxin removal from water is evaluated by quantification using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry. The results show that these activated carbon-coated magnetic beads can remove approximately 20% of microcystin-LR from mili-Q water at concentration levels 60 times higher than the WHO recommended level of 1 μg/L. With the same conditions, 20 % of cylindrospermopsin is also captured. For anatoxin-A, with a much smaller molecular weight, 70% is removed at a six-fold lower concentration. Toxin removal increases throughout the 2-h duration of the experiments. Microcystin-LR adsorption is affected by pH, with a higher removal at highly acidic or alkaline pHs. In addition, these beads can be regenerated and reused for several adsorption cycles. In summary, activated carbon magnetic beads can be used to remove cyanotoxins from water with varying effectiveness, depending on toxin size and solution pH, and they can be reused for several removal cycles after optimized regeneration protocols.

Author Contributions

Conceptualization, L.M.B., N.V. and J.R.; methodology, A.C. and L.d.C.A.; sofware A.C., C.C., N.V. and Y.P., validation N.V., J.R., Y.P. and M.C.L.; formal analysis A.C., C.C., S.R.-G. and N.V.; investigation A.C., L.d.C.A. and N.V.; writing—original draft preparation, A.C. and L.d.C.A.; writing—review and editing, N.V., Y.P., J.R. and L.M.B.; supervision, N.V., Y.P. and M.C.L.; project administration, N.V. and J.R., funding acquisition N.V., L.M.B., Y.P. and J.R. All authors have read and agreed to the published version of the manuscript.


The research leading to these results has received funding mainly from grant PID2020-112626RB-C21 funded by MCIN/AEI/10.13039/501100011033, modalities «Research Challenges» and «Knowledge Generation», and also from the following FEDER cofunded-grants from Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia, GRC (ED431C 2021/01), from European Union Interreg Agritox EAPA-998-2018, and H2020 778069-EMERTOX and from Spanish Ministry of Science and Innovation IISCIII/PI19/001248.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Not applicable.

Conflicts of Interest

The authors declare no conflict of interest.
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MDPI and ACS Style

Cao, A.; Vilariño, N.; de Castro Alves, L.; Rivas, J.; Piñeiro, Y.; Costas, C.; Louzao, M.C.; Raposo-García, S.; Botana, L.M. Cyanotoxin Removal from Water Using Activated Carbon Magnetic Beads . Biol. Life Sci. Forum 2022, 14, 16.

AMA Style

Cao A, Vilariño N, de Castro Alves L, Rivas J, Piñeiro Y, Costas C, Louzao MC, Raposo-García S, Botana LM. Cyanotoxin Removal from Water Using Activated Carbon Magnetic Beads . Biology and Life Sciences Forum. 2022; 14(1):16.

Chicago/Turabian Style

Cao, Alejandro, Natalia Vilariño, Lisandra de Castro Alves, José Rivas, Yolanda Piñeiro, Celia Costas, M. Carmen Louzao, Sandra Raposo-García, and Luis M. Botana. 2022. "Cyanotoxin Removal from Water Using Activated Carbon Magnetic Beads " Biology and Life Sciences Forum 14, no. 1: 16.

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