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  • 1
    Electronic Resource
    Electronic Resource
    The role of chitin in uranium adsorption by R. arrhizus (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 2025-2040 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In order to further refine and support the uranium biosorption mechanism hypothesis proposed for Rhizopus arrhizus, uranium competitive equilibrium uptake isotherms by chitin were determined at two different solution pH levels and in the presence of different concentrations of competing ions, namely, Cu2+, Zn2+, and Fe2+. The co-ion effect became more poronounced as the co-ion concentration in solution and pH increased. Obtained equilibrium data are in agreement with uranium biosorption data reported earlier. Infrared, mass, and electron paramagnetic resonance (EPR) spectra of chitin before and after uranium uptake in the presence of the competing ions Cu2+, Zn2+, and Fe2+ were recorded. The combination of the spectral data and the information from equilibrium studies supported the hypothesis advanced earlier on the mechanism of uranium uptake by R.arrhizus. In addition, the data suggested the participation of a free radical in uranium coordination by the cell wall chitin. The mechanism of reduction of the uranium uptake capacity of the biomass in the presence of competing ions was also elucidated further.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260250812
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Biosorption of uranium and thorium (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 23 (1981), S. 583-604 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Selected samples of waste microbial biomass originating from various industrial fermentation processes and biological treatment plants have been screened for biosorbent properties in conjunction with uranium and thorium in aqueous solutions. Biosorption isotherms have been used for the evaluation of biosorptive uptake capacity of the biomass which was also compared to an activated carbon and the ion exchange resin currently used in uranium production processes. Determined uranium and thorium biosorption isotherms were independent of the initial U or Th solution concentration. Solution pH affected the exhibited uptake. In general, lower biosorptive uptake was exhibited at pH 2 than at pH 4. No discernible difference in uptake was observed between pH 4 and pH 5 where the optimum pH for biosorption lies. The biomass of Rhizopus arrhizus at pH 4 exhibited the highest uranium and thorium biosorptive uptake capacity (g) in excess of 180 mg/g. At an equilibrium uranium concentration of 30 mg/liter, R. arrhizus removed approximately 2.5 and 3.3 times more uranium than the ion exchange resin and activated carbon, respectively. Under the same conditions, R. arrhizus removed 20 times more thorium than the ion exchange resin and 2.3 times more than the activated carbon. R. arrhizus also exhibited higher uptake and a generally more favorable isotherm for both uranium and thorium than all other biomass types examined.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260230309
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanism of aluminum interference on uranium biosorption by Rhizopus arrhizus (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 16-27 
    Details
    ISSN: 0006-3592
    Keywords: uranium ; aluminum ; biosorption ; Rhizopus arrhizus ; mechanism ; competing ions ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Uranium competitive uptake experiments by Rhizopus arrhizus were carried out at three different solution pH levels and in the presence of different concentrations of competing aluminum ions in order to examine the competing ion effect. The coion effect became more pronounced as the coion concentration in solution and pH level increased. A preliminary examination of the effect of aluminum on the rate of uranium uptake was also completed. Results showed that the presence of aluminum does not interfere with the kinetics of uranium uptake by R. arrhizus. Electron microscopic and energy dispersive X-ray analyses were also performed on samples of the biomass. The combination of spectral data and the information from the equilibrium studies and the kinetic studies suggested that aluminum interferes with the uranium biosorptive uptake capacity of R. arrhizus by the precipitation of a metastable amorphous hydroxy polymeric precipitate through a mechanism we refer to as steric competition. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 16-27, 1997.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Ionic Competition Effects in a Continuous Uranium Biosorptive Recovery Process (1997)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 70 (1997), S. 198-206 
    Details
    ISSN: 0268-2575
    Keywords: biosorption ; uranium ; immobilized ; biomass ; ionic competition ; aluminium ; silicon ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: -Immobilized Rhizopus arrhizus biomass was studied in a continuous sorption and desorption mode in order to identify factors that affect the long term uranium biosorptive uptake capacity performance of the immobilized biomass. Laboratory-scale continuous operation pilot plant experiments were performed using synthetic uranyl nitrate and industrial uranium mine leachate solutions. Analysis of the liquid solutions indicated that the immobilized Rhizopus arrhizus biomass successfully recovered all of the uranium from the dilute (less than 500 mg U dm-3) solutions. All uranium can subsequently be eluted, yielding highly concentrated uranium eluates. The immobilized Rhizopus arrhizus biomass maintained its uranium biosorptive uptake capacity over 12 successive sorption-elution cycles when synthetic uranyl nitrate solutions were used. However, when used with mine leachate solutions, an 18% reduction in the uranium biosorptive uptake capacity occurred within the first four adsorption-elution cycles. Spectral analysis indicated that, during continuous use and reuse, the immobilized biomass retained its structural integrity. EDAX, scanning and transmission electron microscopic techniques employed on the microbial biomass suggested that the presence of aluminium interferes with the uranium biosorption process. Spectral analysis also indicated that the presence of silicon enhances the negative effect of the presence of aluminium on the uranium biosorptive uptake capacity of the immobilized Rhizopus arrhizus biomass particles. © 1997 SCI
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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