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Continuous Removal and Recovery of Tellurium in an Upflow Anaerobic Granular Sludge Bed (Uasb) Reactor
Published in Joyabrata Mal, Microbial Synthesis of Chalcogenide Nanoparticles, 2018
Tellurite is highly toxic for most bacteria: the minimum inhibitory concentration (MIC) of tellurite ranges between 0.006 - 0.8 mM for microorganisms such as Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa (Harrison et al., 2004; Zannoni et al., 2008). Doubling the tellurite concentration in the influent indeed led to a lower tellurium removal efficiency (~92%) in the UASB reactor (Fig. 7.2). Similar results were reported by Rajwade and Paknikar (2003) for tellurite reduction by P. mendocina MCM B-180: the tellurite removal efficiency dropped from 99 to 80% due to the increase in tellurite concentration from 0.08 to 0.2 mM L−1 in a continuously stirred tank reactor under aerobic conditions over a 25 day period (Rajwade & Paknikar, 2003). However, tellurite removal by UASB reactors is advantageous in terms of separation of the treated water from the biomass, long term operational stability and no energy requirement for bioreactor aeration.
Preparation of zinc tellurides quantum dots and zinc tellurides/multi-walled carbon nanotubes nanocomposites and photocatalytic activity
Published in Inorganic and Nano-Metal Chemistry, 2021
Leila Fatolahi, Alireza Feizbakhsh
About 0.2 g of MWCNTs was dispersed in 50 mL of a H2SO4/HNO3 (2:1). The MWCNTs suspension was sonicated for 3 h at 35 °C. The oxidized MWCNTs (0.1 g) was suspended in70 mL ethylene glycol and sonicated for dispersing of particles. The Zn(O2CCH3)2 (0.1 M) and sodium tellurite [Na2TeO3] (0.1 M) were added to MWCNTs solution. The deionized water, N2H4·H2O and ethylene glycol (9:6:3) was augmented to above suspension. The mixture was stirred for 12 h. Then the 2 mL of 0.1 M polyvinylpyrrolidone was augmented. After that, the mixture was refluxed under stirring at 70 °C for 8 h. Then, the precipitates were washed several times with CH3OH and double distilled water, and finally, calcined at 400 °C for 6 h. The pure ZnTe QDs was synthesized without the presence MWCNTs dispersion stage.
Tellurium Behavior in the Containment Sump: Dissolution, Redox, and Radiolysis Effects
Published in Nuclear Technology, 2021
Anna-Elina Pasi, Henrik Glänneskog, Mark R. St.-J Foreman, Christian Ekberg
The speciation of tellurium in the simulated sump solutions was investigated with IC. This method is suitable for differentiating between tellurium in oxidation states +4 and +6. However, the exact speciation might be affected by matrix effects while the samples pass through the column, and thus the exact speciation might be different. Hence, additional methods may need to be used for complete speciation analysis. The samples were run untreated and undiluted since the concentration of tellurium in the solution was relatively low. However, this caused high peaks for other anions present in higher concentrations in the solution (OH−, B(OH)−4, SO42−, S2O32−). Samples were compared with standard solutions prepared from analytical-grade chemicals. The Te(IV) standard was prepared from sodium tellurite (Na2TeO3) (Sigma Aldrich) and the Te(VI) from H6TeO6 (Sigma Aldrich). Figure 3 presents the main results from the IC measurements. Tellurate, Te(VI), has a retention time of around 6 min. Tellurite, Te(IV), has a slightly longer retention time, however, in the IC system used, Te(IV) was determined indirectly from the negative peak in the chromatogram (III and IV in Fig. 3). This is possibly due to the high positive hydration tendency of the TeO32− species resulting in lower conductivity.44 Moreover, the method was suitable for speciation analysis since only one or the other of the species was present in the sample, and therefore, no separation was required.
Investigation of the Influence of TeO2 on the Elastic and Radiation Shielding Capabilities of Phospho-Tellurite Glasses Doped With Sm2O3
Published in Nuclear Science and Engineering, 2023
Sangeeta B. Kolavekar, G. B. Hiremath, N. M. Badiger, N. H. Ayachit
Recently, Evangelin Teresa et al.15 synthesized Dy-ion-doped alkali boro-tellurite glasses and studied the physical, structural, and elastic features, as well as the radiation parameters, such as the half-value layer (HVL), Zeff, and EBF for selected glasses. Ibrahim et al.16 synthesized the rare earth oxide–doped ZnO-Bi2O3-B2O3 glasses and studied the physical, structural, neutron, and gamma radiation parameters such as HVL, Zeff, and EBF for selected glasses. Mahmoud and Rammah17 studied the MAC, mean free path (mfp), HVL, Zeff, and effective electron density (Aeff) for Y-, Gd-, Nd-, Pr-, and Dy-doped glasses and found that rare earth glass samples (S4-Pr and S5-Dy) have good shielding properties compared to commercially standard RS-520 and zinc bismuth borate glass. Mariselvam18 synthesized the Yb-ion-doped H3BO3-Bi2O3-BaCO3-CaF2-ZnO glasses and studied the structural, physical, optical, and nuclear radiation parameters, such as MAC, linear attenuation coefficient (LAC), Zeff, Neff, EBF, and EABF using Phy-X software. They found that excellent material properties were observed for 2YbBBFB glass. Megala et al.19 synthesized Sm3+ ion–doped fluoroborosilicate glasses using a conventional melt quenching method and studied the photoluminescence and radiation shielding properties. They suggested that SBNCSm05 and SBNCSm20 are potential candidates in photonic device applications and radiation shielding applications.