Abstract
An effective removal process of Sr2+ from polluted solution has been demonstrated by its binding to Azolla biofilter at high affinity, involving ion exchange with Na+, K+, Mg2+ and Ca2+. Maximal Sr2+ binding capacity was as high as 3.5% per Azolla dry weight. The biosorption of Sr2+ was optimal at neutral and high pHs, but lower at acidic pH, due to a competition between Sr2+ and H+ ions on the cation binding groups of Azolla. Pectin, constituting 8–10.5% (w/w) of the Azolla cell wall, is shown to bind a major portion of Sr2+ ions. Treatment with pectinase reduced the binding capacity of Azolla to Sr2+. Methylation of Azolla biomass, known to block the carboxyl groups of pectin by esterification markedly reduced the Sr2+ binding. Optimal Sr2+ binding by Azolla at high pH values indicates deesterification of pectin and exposure of additional available carboxyl groups for metal binding.
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Cohen-Shoel, N., Ilzycer, D., Gilath, I. et al. The Involvement of Pectin in Sr2+ Biosorption by Azolla . Water, Air, & Soil Pollution 135, 195–205 (2002). https://doi.org/10.1023/A:1014720900377
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DOI: https://doi.org/10.1023/A:1014720900377