DETERMINATION OF THE ABILITY OF INACTIVATED AND IMMOBILIZED CELLS OF SYNECHOCOCCUS PCC 7942 (CYANOBACTERIA) TO UPTAKE METAL IONS FROM SOLUTION
|J. L. Gardea-Torresdey1, J.L. Arenas2, R. Webb2, and K. J. Tiemann1, 1Department of Chemistry and 2Department of Biological Sciences, University of Texas at El Paso, El Paso Texas 79968.||
Synechococcus 7942 has the ability to grow in mass quantity under ideal conditions; such an ability provides usable biomass at a minimal effort. Using lyophilized biomass grown under normal conditions, Synechococcus was tested for its potential to bind copper, lead, and nickel ions from solution.
Previous batch experiments have determined the optimum binding pH, time dependency, and metal binding capacities for copper(II), lead(II), and nickel(II), along with desorption of the metal bound. The biomass studied showed a high affinity for all three metal ions, with an optimum binding at pH 5.
Time dependency studies showed that this cyanobacteria had rapid binding, while capacity experiments showed this cyanobacteria strain to bind 11.3 mg of copper(II) per gram of biomass, 30.4mg of lead(II) per gram of biomass, and 3.2 mg of nickel(II) per gram of biomass. More than 90% of copper(II), lead(II) and nickel(II) metal ions were recovered when treated with 0.1M HCl.
Biomass was then immobilized in a silica polymer and tested for its binding ability under flow conditions. Using 0.1mM concentrations of the previously indicated metals, individual experimental results showed that up to 502.4 ppm Cu (II), 1781.3 ppm Pb (II), and 114.9 ppm Ni (II) were bound by the immobilized biomass.
Treatment with 0.2M HCl resulted in 100% recovery for both Cu (II) and Pb (II) from the column, while recovery for Ni (II) was 40%. Data from both batch and column experiments indicate a variation in the sites responsible for metal binding. Results showing many cycles of metal binding-stripping by the immobilized biomass will be presented.
Further, attempts will be made to determine the chemical structure of the different metal binding sites. Synechococcus can eventually be used as a source for a novel approach in using biosystems to remediate contaminants from solution and making those contaminants available to industry through an environmentally friendly biofiltration system.
Key words: synechococcus, cyanobacteria, heavy metal binding, biofiltration, metal recovery.
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