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Abstract  

The study was undertaken to evaluate the feasibility of oxidized multiwalled carbon nanotube (oxidized MWCNT) for the removal of radiocobalt (60Co) from aqueous solutions. The oxygen functional groups of oxidized MWCNT were characterized by FT-IR and XPS. Batch experiments were performed to study the sorption of cobalt as a function of contact time, solid contents, pH, ionic strength, foreign ions, and temperature. Two kinetic models viz. pseudo-first-order and pseudo-second-order were used to determine kinetic sorption parameters, and the kinetic sorption could be described more favorably by the pseudo-second-order model. The thermodynamic parameters (∆G°, ∆S°, ∆H°) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Co(II) on oxidized MWCNT was an endothermic and spontaneous processes. The results suggest that oxidized MWCNT can be used efficiently in the treatment of industrial effluents containing radioactive and heavy metal ions.

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References [1] Marko I. Removal of bromates from water , MSc Thesis , Bratislava, Faculty of Civil

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Abstract  

Clay minerals have been widely used in wastewater disposal due to their strong sorption and complexation ability towards various environmental pollutants. In this study, the removal of Zn(II) from aqueous solution by natural halloysite nanotubes (HNTs) was studied as a function of various solution chemistry conditions such as contact time, pH, ionic strength, coexisting electrolyte ions and temperature under ambient conditions. The results indicated that the removal of Zn(II) by HNTs was strongly dependent on pH and ionic strength. Langmuir and Freundlich models were used to simulate the sorption isotherms of Zn(II) at three different temperatures of 293, 313 and 333 K. The thermodynamic parameters (ΔH 0, ΔS 0 and ΔG 0) calculated from the temperature dependent sorption isotherms indicated that the removal process of Zn(II) by HNTs was endothermic and spontaneous. At low pH, the removal of Zn(II) was dominated by outer-sphere surface complexation and/or cation exchange with Na+/H+ on HNT surfaces, whereas inner-sphere surface complexation was the main removal mechanism at high pH. From the experimental results, one can conclude that HNTs may have a good potentiality for the disposal of Zn(II)-bearing wastewaters.

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Abstract  

Radioactive molten salt generated from a pyrochemical process to separate reusable U and TRU elements is one of problematic wastes to manage for a final disposal. For the minimization of final waste, it is desirable to selectively remove radionuclides from the waste salts. In this paper, structural change of some zeolites in a series of molten salt systems and its removal behavior of CsCl was investigated. Zeolite-4A(LTA) was transformed into LiAlSiO4 and Li-sodalite with the mol-fraction of LiCl in LiCl–KCl system at 650 °C while it was not changed in NaCl–KCl at 750 °C, regardless of mol-fraction of metal chloride. Other commercial zeolite with specific structure (FAU) had the same trends on the structural stability in molten salt system. From the Cs removal experiments, the decomposed zeolitic materials in molten salt lost their removal ability of Cs. In conclusion, a new selective material or method should be investigated or developed for obtaining the validity on the separation of group I and II radionuclides from a molten waste salt because the zeolite 4A is unstable in the LiCl system and it also showed a low capacity in the LiCl–KCl phase. This paper gives basic information on the removal of radionuclides from molten systems by using zeolitic materials.

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Abstract  

Sorption of Na(I), Cs(I) and Co(II) radionuclides from aqueous solutions by titanosilicate have been investigated. The time dependent studies for metal ions showed relatively rapid sorption kinetics between 5 and 30 min to reach equilibrium. A batch adsorption model based on assumption of the pseudo-second-order mechanism was applied to predict the sorption rate, while the equilibrium capacity was calculated at different temperatures. The adsorption of different radionuclides onto titanosilicate was found to be favored at high ions concentrations and low temperature for Na+ and Co2+ while at high temperature for Cs+. Activation energy of adsorption was computed to be 2.35, 24.11 and 5.74 kJ/mol for adsorption of Na(I), Cs(I) and Co(II), respectively. The results revealed that the adsorption of Cs+ is the highest relative to Na+ and Co2+ at different conditions which may be attributed to its low hydration energy. Further, the equilibrium isotherm for the interested ions was analyzed and it was found to obey Frundlich equation.

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sources (e.g. papers) and items (e.g. citations)). In this paper we will study the effect of random removal of sources and/or items on the comparison of the impact of two systems which, initially, have the same h-index. Random removal will, in this paper

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into the sewage sludge by enhanced biological phosphorus removal and/or by precipitation with Ca 2+ -, Fe 2+ -, Fe 3+ -, or Al 3+ -salts in the waste water treatment plant. However, direct agricultural application of sewage sludge became a controversial

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Johnson D. B. Biological removal of sulfurous compounds from inorganic wastewaters, Environmental Technologies to Treat Sulfur Pollution: Principles and Engineering . London, IAWQ, 2000, pp. 175

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Decomposition and removal of carbonizate was performed over platinum catalysts supported on two types of alumina differing in the surface area: low surface area one (LSA) and high surface one (HSA). For the sake of comparison, the performance of platinum catalyst supported on silica and bimetallic platinum-rhenium catalysts was analyzed. It has been shown that all platinum catalysts examined caused an increase in the removal of carbonizate. The activity of these catalysts was independent of the kind of support applied or addition of rhenium as a second component.

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Abstract  

Decomposition and removal of carbonizate was performed over platinum catalysts supported on two types of alumina differing in the surface area: low surface area one (LSA) and high surface one (HSA). For the sake of comparison, the performance of platinum catalyst supported on silica and bimetallic platinum-rhenium catalysts was analyzed. It has been shown that all platinum catalysts examined caused an increase in the removal of carbonizate. The activity of these catalysts was independent of the kind of support applied or addition of rhenium as a second component.

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