Karpenko Y. Biotechnology of attaching of magnetic particles to yeast Saccharomyces cerevisiae as a biosorbent of cations of heavy metals

The dissertation is devoted to the scientific and technical bases of the production biotechnology of magnetically labeled biosorbents by the method of multi-vortical magnetohydrodynamic (MHD) mixing for the purification of wastewater from heavy metal cations. The rational parameters of the attachment process by the method of multi-vortical MHD mixing of suspensions of yeast and nanosize magnetite considering the characteristics of biosorption of cations Cu2+ are determined. Parameters of multi-vortical MHD mixing for the production of the magnetically labeled biosorbent are: pH 2,5 and the strength of permanent magnetic field 240 kA/m. Parameters of the production of a magnetically labeled biosorbent: the mass ratio of the nanosized magnetite to the yeast S. cerevisae – 1%, the duration of multi-vortical MHD mixing – 2 min. The degree of removal by magnetically labeled biosorbent is: 94% of cations Cu2+ at an initial concentration of cations 50 mg/dm3 and 90% of iron cations Fe2+ at an initial concentration of iron 1 mg/dm3. It is proved that the maximum sorption capacity of the magnetically labeled biosorbent is 25.5 mg/g towards cations Cu2+ and 250 mg/g towards iron cations in the case of next parameters of attachment of magnetic particles: the mass ratio of magnetic particles to the yeast – 1%, the duration of multi-vortical MHD mixing is 2 min. It is proved that the isotherms of sorption of cations Cu2+ by native yeast and by magnetically labeled biosorbent with 1% by weight of magnetite, manufactured by mixing at a pH of 2,5 and at an external magnetic field 240 kA/m with a duration of 2 min, are similar, and their maximum sorption capacities differs within an error. The characteristics of the process of biosorption by the magnetically labeled biosorbent on the example of cations of Cu2+ were determined – the constants of the Langmuir model and the constants of the sorption kinetics, depending on the parameters of the process of magnetically labeling of the biosorbent, were determined. It was established that the maximum sorption capacity towards cations Cu2+ decreases from 25,5 mg/g to 21,1 mg/g of absolutely dry substance of sorbent in case of corresponding increase of the attachment duration from 2 to 10 min of multi-vortical MHD mixing of S. cerevisiae and nanosize magnetite Fe3O4.