ИСТИНА

Re (VII), a rare and valuable metal, is predominantly produced from molybdenites and some copper and platinum ores [1]. Due to its special properties, rhenium is extensively used in petrochemical, metallurgy, medicine, defense, aviation, chemical, and alloy production industries. Data on the adsorption efficiency of microorganisms for rhenium are not widely reported in the literature. The biosorption and bioaccumulation of ReO4 − by the bacterium Bacillus sp. GT-83 was reported by [1] and [2]. Motaghed and co-authors investigated the process of rhenium recovery from a spent refinery catalyst by bacteria Bacillus megaterium. Rhenium is the closest chemical analogue of technetium. The information on Tc behavior in the presence of microorganism could be indicative for rhenium behavior predictions. The present study evaluated the potential of Spirulina platensis biomass to remove rhenium ions from both batch solutions and industrial effluents. The concentration of rhenium ions in solutions was determined by ICP-MS and colorimetric according to Malouf and White [3]. Rhenium content in biomass was determined by means of neutron activation analysis The effects of various parameters such as pH, contact time, initial concentration, and the temperature of biosorbent treatment were investigated. The maximum biosorption capacity of lead was 142.9 mg/g at pH of 2.0, sorbent dosage=0.05 g, and temperature of biosorbent treatment 30 ºC. The Langmuir and Freundlich adsorption isotherm models were found to fit well the sorption equilibrium of the experimental data (R2 = 0.99), while the kinetic data were best described using the pseudo second-order kinetic model (R2> 0.99). FTIR spectra indicated that rhenium removal takes place through two mechanisms: ionic interactions of perrhenate anions with amide and amino-groups, and binding to organic functional groups of the cell surface. The rhenium bound to the biomass could be effectively stripped using NH4OH (8 %) and the biomass was effectively used for three sorption–desorption cycles. In the case of industrial effluents, Spirulina platensis biomass has been shown to have relatively high removal efficiency (51-55%). The study demonstrates the potential of Spirulina platensis as biosorbent to remove rhenium from industrial effluents.