This study assesses the ability of mycelia of Rhizopus delemar (both free and immobilized on polyurethane foam) to remove heavy metals from single-ion solutions as well as from a mixture of them. All experiments were conducted using 0.5-5 mm solutions of CuSO4·5H2O, CoCl2·6H2O and FeSO4·7H2O. Mycelia immobilized on polyurethane foam cells showed some times increase in uptake compared with that of free cells. Metal ions accumulation from a mixed solution was decreased slightly for cobalt and iron and considerable for copper ions. Heavy metal uptake was examined in the immobilized column experiments and more than 92% heavy metal removal (mg heavy metals removed/mg heavy metals added) from a mixed solution was achieved during the 5 cycles. During these experiments, the dry weight of the immobilized cells was decreased by only 2%. These results showed that immobilized mycelia of Rhizopus delemar can be used repeatedly for removal of heavy metals from aqueous solutions.

that, unlike the parent complex, which exhibits a conductivity value expected for a 2:1 electrolyte (AM = 240 "1 cm"1 mol"1 for 8 X 10"4 M complex in acetonitrile), the peroxide complex behaves like a 1:1 electrolyte ( = 147 "1 cm"1 mol"1 for 8 X "4 M complex in acetonitrile).64 We thus propose that peroxide binding appears to result in the replacement of the µwith a µ-1:»!1 peroxide moiety with the retention of the basic ligand coordination around the dibridged dinuclear center (Figure 7a). This proposed structure for [Fe2(HPTB)(02)(N03)2]N03 is different from that proposed for the dioxygen adduct of [Fe2(iV-Et-HPTB)-(OBz)](BPh4)2,27 which consists of a tribridged diferric core analogous to the 2+ cation in Figure 7b with benzoate replacing nitrate. The structural differences in the two peroxide complexes may be reflected in the subtle changes in their UV-vis, Raman, and Mdssbauer parameters (Tables III and IV).All of the diferric peroxide complexes studied thus far appear to favor peroxide bridge formation, and none of these complexes model the dioxygen-binding mode found for oxyhemerythrin- 56 Those capable of reversible dioxygen binding derive from (63) Brennan, B. A.; Chen, Q.; Que, L., Jr. Unpublished results.

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