The use of clay and biomass mixtures for the removal of toxic metals or radionuclides attracts attention because of the impact of sorption capacity of both sorbents. It was recently shown that biomass of melanin-producing microfungi Cladosporium cladosporioides grown on media containing bentonite could be successfiilly used as a biomineral sorbent of radiocaesium. The aim of present investigation was to demonstrate the possibility of using of fungal biomass of Cladosporium cladosporioides grown on media containing different clays from Ukrainian deposits to remove radiostrontium (~(90)Sr) and radiocaesium (~(137)Cs) from aqueous solutions. Adsorption isotherms were examined by varying the concentration of Sr and Cs from 1-20 Bq/ml. The two generic types of kaolinites from the Prosyanovskoe and Glukhovskoe deposits and palygorskite and natural mixture of palygorskite and montmorillonite from Cerkassy deposit were used. The clay minerals altered the growth, size and sorption properties fungal pellets. The addition of 0.5 percent of clays into media led to reduction of the specific area of obtained biomineral sorbents and their sorption capacity. The increase of the concentration of all tested clays up to 5 percent caused a two-fold decrease in fungal pellet size. Fungal biomass grown on media containing 5 percent of Glukhovsky kaolinite demonstrated enhanced ability to sorb ~(90)Sr (2670 Bq/g) compared to pure clay (1951 Bq/g) and pure biomass (1551 Bq/g). Less significant increase of sorption capacity to caesium- 137 and strontium-90 was found in the case of 5 percent of Prosyanovsky kaolinite. The positive correlation between an increase of sorption capacity and a decrease of fungal pellet size while increasing concentration of clays up to 5 percent was observed. The difference between predicted and experimentally obtained values of radionuclides uptake in the mixtures of clays and biomass was demonstrated.
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