ABSTRACT
Development of useful all-around materials which can quickly and efficiently adsorb radionuclides in response to environmental radioactive contamination is an urgent research objective. In response to this need, our team developed a simple preparation method for stable sodium titanates which can serve as efficient agents for removal of radionuclides from water. With an emphasis on an environmentally friendly synthesis, the resulting materials were defined by a range of means and methods measuring e.g. pH, ionic strength, contact time or metal ion concentration in order to assess their potential for use and applications as sorbents. The data obtained from measurements revealed rapid removal kinetics (up to 10 minutes), wide range of pH use and high equilibrium capacity. The maximum amount of adsorbed ions as calculated from the Langmuir isotherm was equal to 206.3 mg g-1 for Cs(i), 60.0 mg g-1 for Sr(ii), 50.2 mg g-1 for Co(ii) and 103.4 mg g-1 for Eu(iii), significantly exceeding published data obtained with related materials. The removal mechanism is most likely ion exchange followed by complexation reactions, as indicated by TEM/EDS analyses. Given their extraordinary sorption capacity and facile synthesis under mild conditions, these materials are promising candidates for the efficient removal of radionuclides from aqueous solutions during the clean-up of radioactive pollution in the environment.
ABSTRACT
Zeolites have been investigated as sorbents of heavy metals from water. Since graphene oxide was already reported as promising radionuclide sorbent, we developed composite materials containing both a synthetic zeolite (type A, P or Y) and graphene oxide to be multifunctional sorbents. The extension of multifunctionality of sorbents was done by presence of third component, exfoliated graphite, to have additional properties as conductivity. The changing sorption activities of a composite was studied depending on its composition and functional modification. The composites, characterized by X-ray powder diffraction, Raman, FTIR spectroscopy and scanning electron microscopy, were tested for sorption of selected radionuclides (134Cs+, 85Sr2+) and heavy metals (Pb2+, Cd2+). The dependency on composition was found in connection with a high sorption of Pb2+ and Cd2+. Finally, optimized multifunctional sorbents (Gr-GO-COOH-A in ratio 40:40:20 and Gr:GO:A in ratio 25:25:50) were found to keep interesting high sorption activities for heavy metals and radionuclides with good conductivity properties.
ABSTRACT
Electrospun polymeric nanofiber materials doped with 5,10,15,20-tetraphenylporphyrin (TPP) photosensitizer were prepared from four different polymers and were characterized with microscopic methods, steady-state, and time-resolved fluorescence and absorption spectroscopy. The polymers used included polyurethane Larithane™ (PUR), polystyrene (PS), polycaprolactone (PCL), and polyamide 6 (PA6). The antibacterial activity of all nanofiber materials against E. coli was activated by visible light and it was dependent on oxygen permeability/diffusion coefficients and the diameter of the polymeric nanofibers. This activity is based on oxidation ability of singlet oxygen O2(¹Δ(g)) that is generated upon irradiation. All tested nanofiber materials exhibited prolonged antibacterial properties, even in the dark after long-duration irradiation. The post-irradiation effect was explained by the photogeneration of H2O2, which provided the material with long-lasting antibacterial properties.
