The adsorption of U(VI) and Hg(II) on Paecilomyces catenlannulatus proteases
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The adsorption of U(VI) and Hg(II) on Paecilomyces catenlannulatus proteases Fengbo Li • Zhimou Gao • Xiaoyu Li Lejin Fang
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Received: 14 June 2013 Ó Akade´miai Kiado´, Budapest, Hungary 2013
Abstract The adsorption of U(VI) on Paecilomyces catenlannulatus as a function of agitation time, pH and solution concentration was investigated by batch techniques. Hg(II) cation was also employed to compare the adsorption capacity of P. catenlannulatus in this study. The adsorption kinetics indicate that the adsorption of U(VI) and Hg(II) on P. catenlannulatus can be fitted by pseudosecond kinetic model very well. The optimum pH for U(VI) removal was 7.0, whereas the high level of adsorption of Hg(II) was observed at pH [7.0 due to the occurrence of precipitate (i.e., Hg(OH)2(s)). The maximum adsorption capacity of P. catenlannulatus calculated from Langmuir model was 163.93 and 140.85 mg g-1 for U(VI) and Hg(II), respectively. This paper highlights the application of P. catenlannulatus as suitable bio-materials for the preconcentration and removal of radionuclides from aqueous solutions in environmental pollution management. Keywords Adsorption Bimass Paecilomyces catenlannulatus Uranium(VI)
Introduction A large number of radioactive wastes such as uranium occur at nuclear material production and U mining sites.
F. Li (&) X. Li L. Fang The School of Life Science and Environmental Science, Huangshan University, Huangshan 245041, China e-mail: [email protected] Z. Gao The College of Plant Protection, Anhui Agricultural University, Hefei 230036, China
Uranium exists in the environment primarily in the U(VI) at oxidized states and U(IV) ions at anaerobic conditions, whereas insoluble U(IV) ions can be immobilized in aqueous sediment due to the formation of some uranium ore [1, 2]. The mobilization of U(VI) has been a major concern in aqueous solution where complexation with carbonate reduces adsorption and increases mineral solubility at high pH conditions, facilitating the transport of U(VI) in the subsurface environment [3, 4]. Therefore, the removal of uranium by various inorganic adsorbents such as metal oxides [5–8], clay minerals [9–11] and carbonbased materials [12–14] have been studied extensively in recent years. In these studies, the effects of environmental factors such as pH, ionic strength and humic substances on uranium adsorption on the solid particles were investigated. However, the low adsorption capacity limited their application in the removal of radionuclides form large volumes of aqueous solutions in practical application. Recently, the bioadsorption of U(VI) by biomass have been investigated extensively [15–20]. Paecilomyces, is a genus of nematophagous fungus which kills harmful nematodes by pathogenesis, causing disease in the nematodes. Paecilomyces has been also regarded as a promising adsorbents to remove heavy metals such as Cr(VI) [21–23], Hg(II) [24–26], Cd(II) [27], Co(II) [28], Zn(II) [29], Pu(VI) [30], Sr(II) [31], Ag(I) [32], As(V) [33]. However, to the author’s knowledge, the litt
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