Metabolism-independent binding of toxic metals by Ulva lactuca: Cadmium binds to oxygen-containing groups, as determined by NMR

Elizabeth A. Webster (Lead / Corresponding author), Andrew J. Murphy, John A. Chudek, Geoffrey M. Gadd

    Research output: Contribution to journalArticlepeer-review

    25 Citations (Scopus)

    Abstract

    The metabolism-independent metal binding characteristics of Ulva lactuca were investigated using both freeze-dried thalli and cell walls stripped of intracellular material by incubation in Triton-X followed by methanol. Biosorption of Cd, Zn, Cu and Co by freeze-dried thallus was concentration-dependent and followed Freundlich and Langmuir isotherms. The Freundlich plot suggested that freeze-dried U. lactuca had the greatest binding affinity for Cu compared with Cd, Zn and Co. The BET (Brunauer-Emmett-Teller) plot, which indicates a more complex form of adsorption, and the Scatchard plot were not adequate models for Cu adsorption. The Scatchard plot of Cd suggested that two Cd binding sites were available on the freeze-dried thallus, with the second, lower affinity site only becoming available at Cd loading capacities greater than 4.9 μmol g-1 dry wt. 113Cd nuclear magnetic resonance (NMR) studies confirmed that two binding sites were available for Cd on the freeze-dried algal powder, though only one was available on the cell wall, and that the affinity of the binding sites was greater for Cu than for Cd.The results of the NMR experiments suggested that Cd binds to oxygen-containing functional groups in the algal powder and on the cell wall. It is proposed that sulphate or hydroxyl groups attached to polysaccharide subunits are possible sites.

    Original languageEnglish
    Pages (from-to)105-117
    Number of pages13
    JournalBioMetals
    Volume10
    Issue number2
    DOIs
    Publication statusPublished - Jun 1997

    Keywords

    • BET
    • Biosorption
    • Cadmium
    • Cobalt
    • Copper
    • Freundlich
    • NMR
    • Scatchard
    • Ulva lactuca
    • Zinc

    ASJC Scopus subject areas

    • Biomaterials
    • General Biochemistry,Genetics and Molecular Biology
    • General Agricultural and Biological Sciences
    • Metals and Alloys

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