Browsing by Subject "Lead"

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    “Nanotraps” in porous electrospun fibers for effective removal of lead(II) in water
    (Royal Society of Chemistry, 2016-02) Senthamizhan A.; Balusamy, B.; Celebioglu A.; Uyar, Tamer
    Here, we have put in conscientious effort to demonstrate the careful design of binding sites in fibers and their stability for enhanced adsorption of metal ions, which has proven to be a challenging task until now. Dithiothreitol capped gold nanoclusters (AuNCs) are successfully encapsulated into a cavity in the form of pores in electrospun porous cellulose acetate fibers (pCAFs) and their assembly creates a "nanotrap" for effective capture of Pb2+. The enhanced immobilization capacity of AuNCs into the interiors of the fibers and their non-aggregated nature offer enhanced adsorption sites, thus reaching maximum extraction capacity up to 1587 mg g-1 for Pb2+. The remarkable finding from this approach has shown that the diffusion of Pb2+ into the interiors of the AuNC encapsulated porous cellulose acetate fiber (pCAF/AuNC) is in line with the penetration depth of AuNCs. The effectiveness of the pCAF/AuNC has been compared with that of the AuNC decorated non-porous cellulose acetate fibers (nCAF/AuNC). The findings have shown a remarkable improvement in the adsorption efficiency by increasing the availability and stability of adsorption sites in the pCAF/AuNC. We strongly believe that the proposed approach might provide a new insight into developing nanotraps to eliminate the usual limitations including denaturation of adsorbents on supported matrices. © The Royal Society of Chemistry 2016.
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    Phytoremediation of Cu, Cr and Pb mixtures by lemna minor
    (2013) Üçüncü, E.; Tunca, E.; Fikirdeşici, S.; Özkan, A.D.; Altindaǧ, A.
    The present study reports the capacity of the aquatic macrophyte Lemna minor to remediate combinations of Cu(II), Pb(II) and Cr(III) from a simulated natural environment. The effect of these metal mixtures on the growth of L. minor was also investigated using growth rate and biomass inhibition calculations. L. minor was successful in removing Cr and Pb from the water, and it remained an effective remediation agent when both metals were present in the environment. However, a relatively low absorption capacity was observed for Cu, increasing concentrations of which were associated with significant decreases in growth rate. No statistically significant difference was found between the 24 h and 7 days absorption rates of Cu, Pb and Cr, suggesting that, at the concentrations tested, equilibrium occurs within 24 h of metal exposure. © 2013 Springer Science+Business Media New York.
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    Sedimentlerde radyoizotopik yöntemlerle yaş tayini
    (Scientific and Technical Research Council of Turkey - TUBITAK, 2001) Erten, Hasan N.
    Sedimentlerde yaş tayini, sediment boyunca kimyasal element dağılımı ile birlikte ele alınınca doğal ve kültürel olayların çevresel etkilerinin belirlenmesinde çok önemli rol oynamaktadır. Doğal 238U radyoaktif serisinin bir ürünü olan 210Pb (t1/2= 22.3y) kullanılarak sedimentlerde son 200 yılı kapsayan bir süre içinde yaş tayini yapmak mümkün olmaktadır. Diğer yandan çevrede yapay olarak bulunan 137Cs (t1/2= 30.1y) izotopunun sediment boyunca dağılımı incelemelerinden 1954-1963 yıllarındaki yeryüzünde yapılan nükleer silah denemelerinin sonucunda ve 1986 yılındaki Çernobil kazasında çevreye yayılan 137Cs’nin dağılım profillerinden söz konusu tarihleri belirlemek mümkün olmaktadır. Bu yöntem 210Pb ile birlikte kullanıldığı zaman güvenilir sediment çökelme hızı tayinleri yapılabilmektedir. Diğer yandan bir kozmik ışın ürünü olan 7Be(t1/2=53.3g) izotopunun incelenmesi ise sediment örneklerinin kayıpsız elde edilişlerini belirlemektedir. Radyoizotopik yöntemler klasik yöntem olarak kullanılan katman sayma yöntemi ile karşılaştırılabilir. ˙