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    Öğe
    Immobilization of Saccharomyces cerevisiae on to acrylamide-sodium acrylate hydrogels for production of ethyl alcohol
    (Elsevier Science Inc, 2003) Öztop, HN; Öztop, AY; Karadag, E; Isikver, Y; Saraydin, D
    Acrylamide/sodium acrylate (AAm/SA) copolymers, prepared by using various crosslinkers, were used in experiments on swelling, diffusion, immobilization of yeast cells (Saccharomyces cerevisiae) and production of ethyl alcohol. AAm/SA hydrogels were used for swelling and diffusion studies in the nutrient medium of the cells. The parameters of equilibrium swelling, maximum swelling, initial swelling rate, diffusional exponent, network constant and diffusion coefficient of the hydrogel/penetrant systems were calculated and evaluated. Yeast cells were immobilized onto the hydrogels by adsorption method during multiplication and ethyl alcohol production of the hydrogels was investigated. Swelling of AAm increased with the addition of SA and ethyl alcohol production increased with increasing SA in the hydrogels. The best system for immobilization is found to be AAm/SA hydrogels containing N,N'-methylenebisacrylamide as crosslinker. (C) 2002 Elsevier Science Inc. All rights reserved.
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    Öğe
    Radiation crosslinked poly(acrylamide/2-hydroxypropyl methacrylate/maleic acid) and their usability in the uptake of uranium
    (Taylor & Francis Inc, 2002) Saraydin, D; Solpan, D; Isikver, Y; Ekici, S; Güven, O
    The terpolymeric poly(acrylamide/2-hydroxy propylmethacrylate/maleic acid) (AAm/HPMA/MA) hydrogels in the rod form have been prepared by gamma radiation of quaternary mixtures of acrylamide/2-hydroxy propylmethacrylate/ maleic acid/water. Spectroscopic and thermal analyses of AAm/HPMA/MA were made. The hydrogels were used in experiments on swelling, diffusion and adsorptions of uranyl ions from aqueous uranyl acetate solutions. For the hydrogels, the parameters of swelling and diffusion were calculated. In the experiment of uranyl ions adsorption, Type L (Langmuir) adsorption isotherm in Giles classification system was found. Binding parameters such as the initial binding constant (K-i), the equilibrium binding constant (K), monolayer coverage (n), site-size (u), maximum fractional occupancy (theta) were calculated for hydrogel/uranyl ion system by using the linearization methods such as Klotz, Scatchard and Langmuir methods. Thermodynamic parameters such as adsorption free energy (DeltaG), adsorption enthalpy (DeltaH) and adsorption entropy (DeltaS) were also calculated. Finally, the effect of MA contents of the hydrogel and irradiation doses was Studied on the adsorption of uranyl ion from its aqueous solution.