Ferrate(VI) mediated degradation of the potent cyanotoxin, cylindrospermopsin: Kinetics, products, and toxicity

•Kinetic investigation shows elimination of cylindrospermopsin by Fe(VI) in minutes.•Identified oxidized products demonstrate attack on uracil moiety of CYN by Fe(VI).•Toxicity tests supports removal of toxic uracil moiety by Fe(VI).•Removal of CYN by Fe(VI) was also seen in presence of humic acid i...

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Published in:Water research (Oxford) 2023-04, Vol.233, p.119773-119773, Article 119773
Main Authors: Zhao, Cen, Arroyo-Mora, Luis E., DeCaprio, Anthony P., Dionysiou, Dionysios D., O'Shea, Kevin E., Sharma, Virender K.
Format: Article
Language:English
Subjects:
Biological activity
Cyanobacteria Toxins
Drinking Water
Ferrate
Humans
Humic acid
Kinetics
Mechanism
Oxidation
Oxidation-Reduction
Toxin
Uracil - chemistry
Water Pollutants, Chemical - chemistry
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Summary:•Kinetic investigation shows elimination of cylindrospermopsin by Fe(VI) in minutes.•Identified oxidized products demonstrate attack on uracil moiety of CYN by Fe(VI).•Toxicity tests supports removal of toxic uracil moiety by Fe(VI).•Removal of CYN by Fe(VI) was also seen in presence of humic acid in water.•Complete degradation of CYN in lake water by Fe(VI) was observed. The presence of cylindrospermopsin (CYN), a potent cyanotoxin, in drinking water sources poses a tremendous risk to humans and the environment. Detailed kinetic studies herein demonstrate ferrate(VI) (FeVIO42−, Fe(VI)) mediated oxidation of CYN and the model compound 6-hydroxymethyl uracil (6-HOMU) lead to their effective degradation under neutral and alkaline solution pH. A transformation product analysis indicated oxidation of the uracil ring, which has functionality critical to the toxicity of CYN. The oxidative cleavage of the C5=C6 double bond resulted in fragmentation of the uracil ring. Amide hydrolysis is a contributing pathway leading to the fragmentation of the uracil ring. Under extended treatment, hydrolysis, and extensive oxidation lead to complete destruction of the uracil ring skeleton, resulting in the generation of a variety of products including nontoxic cylindrospermopsic acid. The ELISA biological activity of the CYN product mixtures produced during Fe(VI) treatment parallels the concentration of CYN. These results suggest the products do not possess ELISA biological activity at the concentrations produced during treatment. The Fe(VI) mediated degradation was also effective in the presence of humic acid and unaffected by the presence of common inorganic ions under our experimental conditions. The Fe(VI) remediation of CYN and uracil based toxins appears a promising drinking water treatment process. [Display omitted]
ISSN:0043-1354
1879-2448
DOI:10.1016/j.watres.2023.119773