Abstract
The aquatic fern Azolla binds heavy metals in a widerange of concentrations with high effectiveness, and it can therefore be used for the decontamination of polluted solutions.We have tested the application of its biomass as a practicalbiofilter for industrial waste treatment. In this report, we describe the properties of Azolla biomass which has been dried, rewetted and packed in columns, for use as an ion-exchange matrix. We used scanning electron microscopy in conjunction with an elemental analysis of the Azolla biomass to investigate its structure and to localize exchangeablecations. Azolla elemental content and model solutions containing Sr2+ eluted through the biofilter were analyzed.The Azolla biofilter bound Sr2+ ions efficientlyby ion exchange with K+, Na+, Ca2+ and Mg2+. K+ and Na+ ions were eluted during the initial phaseof Sr2+ binding, due to their lower affinity to the cation-binding groups in the Azolla cell wall. Ca2+ and Mg2+, bound with a higher affinity to theAzolla cation-binding groups, were exchanged during the secondary phaseof Sr2+ binding. Pre-loading of the metal-binding groups with K+ increased the removal of heavy metals from solutionby the Azolla biofilter. Our observations explain the mechanism of heavy-metal adsorption to the Azolla matrix.
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Cohen-Shoel, N., Barkay, Z., Ilzycer, D. et al. Biofiltration of Toxic Elements by Azolla Biomass. Water, Air, & Soil Pollution 135, 93–104 (2002). https://doi.org/10.1023/A:1014724408952
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DOI: https://doi.org/10.1023/A:1014724408952