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Summary  

Kinetics and equilibrium studies on the sorption of uranium and thorium ions were carried out from nitric acid solutions by tri-n-butyl phosphate (TBP) loaded supported sorbent, commercially known as Egy-Sorb, using batch technique. Analysis of the rate data in accordance with three kinetic models revealed that the particle diffusion process was the rate determining mechanism and the sorption process of the metal ions onto impregnated sorbent follows first order reversible kinetics. The values of the first order rate constants, the rate constants of intraparticle transport, and the particle diffusion coefficients for the uranium and thorium ions were determined from the graphical representation of the proposed models. Experimental isotherms of both ions were successfully fit to Langmuir and Freundlich isotherm models over the entire concentration range studied. The effect of temperature on the equilibrium distribution values has been utilized to evaluate the changes in standard thermodynamic quantities.

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Abstract  

Sorption of124Sb(III) from benzene, toluene, o-xylene and nitrobenzene on treated fly ash, pyrolysis residue and bentonite clay was studied at room temperature using the batch method. In comparison to a former study for the sorption of124Sb(V), the results revealed relatively higher sorption of the trivalent state than the pentavalent one. According to the type of the nonpolar solvent used, the order of uptake of the radioactive isotopes was often o-xylenetoluene>benzene. The sorption tendency of the sorbents used towards the radionuclides was: bentonitepyrolysis residue>treated fly ash. Sorption from an aqueous medium on the same sorbents has also been investigated for124Sb(III) compared to124Sb(V),152Eu(III) and their mixtures. The obtained results showed that the order of uptake of the different radionuclides was: Eu(III)>>Sb(III)>Sb(V)>mixture. The investigation was extended to the desorption studies of these radionuclides in the acidic and the neutral media from the dried radioactivity loaded sorbents.

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and more stringent regulations for the control of environmental pollution has encouraged the search for more efficient desulfurization processes [ 1 , 2 ]. SO 2 in situ capture using calcium-based sorbents such as limestone and dolomite during coal

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Abstract  

The paper deals with the study of inorganic acid uptake on hydrogels of titanium, zirconium, and tin hydroxides prepared by the sol-gel method in the form of regular spherical particles. The aim of the work was the determination of the basic conditions for the preparation of inorganic ion exchangers by means of the conversion of the hydroxide gel. The results obtained prove that the exchange of hydroxide groups of the gel phase for the respective anions plays the decisive role in the uptake on zirconium hydroxide. With similar titanium and tin compounds, the main process affecting the uptake is the formation of adsorption compounds and the free diffusion of the electrolyte into the gel phase. The possibilities of the application of the sol-gel method for the preparation of inorganic sorbents are discussed.

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Abstract  

In the present study, Mg–Al layered double hydroxide intercalated with nitrate anions (LDH-NO3) was synthesized, modified with the anionic surfactant, sodium lauryl sulfate, and applied for the removal of 152+154Eu from aqueous solutions. Modification of the as-synthesized Mg–Al layered double hydroxide was carried out at surfactant concentration of 0.01 M (the organo-LDH produced denoted LDH-NaLS). The as-synthesized and surfactant-intercalated LDHs were characterized by FT-IR and energy-dispersive X-ray spectroscopy techniques. The effect of some variables such as solution pH, contact time and sorbate concentration on removal of 152+154Eu was investigated. The kinetic data obtained were well fitted by the pseudo-second-order kinetic model rather than the pseudo-first-order model. Intraparticle diffusion model showed that sorption of 152+154Eu proceed by intraparticle diffusion together with boundary layer diffusion. Experimental isotherm data were well described by Langmuir model. Organo-LDH was found to have higher capacity (156.45 mg g−1) for europium than the as-synthesized LDH-NO3 (119.56 mg g−1). Comparing LDHs capacities obtained for Eu(III) in the present work with other sorbents reported in literature indicated that LDHs have the highest capacities. Application of the developed process for removal of 152+154Eu(III) from radioactive process wastewaters was also studied and the obtained results revealed that these LDHs are promising materials for treatment of radioactive wastewaters.

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Abstract  

PET with 68Ga from the TiO2- or SnO2- based 68Ge/68Ga generators is of increasing interest for PET imaging in nuclear medicine. In general, radionuclidic purity (68Ge vs. 68Ga activity) of the eluate of these generators varies between 0.01 and 0.001%. Liquid waste containing low amounts of 68Ge activity is produced by eluting the 68Ge/68Ga generators and residues from PET chemistry. Since clearance level of 68Ge activity in waste may not exceed 10 Bq/g, as stated by European Directive 96/29/EURATOM, our purpose was to reduce 68Ge activity in solution from >10 kBq/g to <10 Bq/g; which implies the solution can be discarded as regular waste. Most efficient method to reduce the 68Ge activity is by sorption of TiO2 or Fe2O3 and subsequent centrifugation. The required 10 Bq per mL level of 68Ge activity in waste was reached by Fe2O3 logarithmically, whereas with TiO2 asymptotically. The procedure with Fe2O3 eliminates ≥90% of the 68Ge activity per treatment. Eventually, to simplify the processing a recirculation system was used to investigate 68Ge activity sorption on TiO2, Fe2O3 or Zeolite. Zeolite was introduced for its high sorption at low pH, therefore 68Ge activity containing waste could directly be used without further interventions. 68Ge activity containing liquid waste at different HCl concentrations (0.05–1.0 M HCl), was recirculated at 1 mL/min. With Zeolite in the recirculation system, 68Ge activity showed highest sorption.

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Abstract  

The industrial pollution is exponentially growing in the developing countries due to the discharge of untreated effluents from the industries in the open atmosphere. This may cause severe health hazards in the general public. To reduce this effect, it is essential to remove the toxic and heavy metals from the effluents before their disposal into the biosphere. In this context, samples of the effluents were collected from the textile/yarn, ceramics and pulp/paper industries and the concentrations of the toxic metal ions were determined using neutron activation analysis (NAA) technique. The observed concentration values of the As, Cr and Fe ions, in the unprocessed industrial effluents, were 4.91 ± 0.8, 9.67 ± 0.7 and 9.71 ± 0.8 mg/L, respectively which was well above the standard recommended limits (i.e. 1.0, 1.0 and 2.0 mg/L, respectively). In order to remove the toxic metal ions from the effluents, the samples were treated with pea nut husk fence. After this treatment, 91.5% arsenic, 81.9% chromium and 66.5% iron metal ions were successfully removed from the effluents. Then the treated effluents contained concerned toxic metal ions concentrations within the permissible limits as recommended by the national environmental quality standards (NEQS).

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Certain micro-chemical separations using hydrous ferric oxide as a selective sorbent

I. Micro-analysis of binary mixtures of zinc with copper and nickel

Journal of Radioanalytical and Nuclear Chemistry
Authors: Brij Bhushan and K. Kar

Abstract  

Separation of zinc from copper and nickel by the selective sorption of Zn(en)3 2+ on hydrous ferric oxide is reported. The details of the batch procedure and the tests of the separation efficiency are described.

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Certain micro-chemical separations using hydrous ferric oxide as a selective sorbent

II. Separation and determinations of small amounts of cadmium from copper and from nickel

Journal of Radioanalytical and Nuclear Chemistry
Authors: Brij Bhushan and K. Kar

Abstract  

Traces of cadmium from relatively high amounts of nickel and copper can be separated by the selective sorption of the cadmium ethylenediamine complex on hydrous ferric oxide. A batch chromatographic technique has been elaborated on this basis.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: G. Lujanienė, S. Meleshevych, V. Kanibolotskyy, J. Šapolaitė, V. Strelko, V. Remeikis, O. Oleksienko, K. Ribokaitė, and T. Ščiglo

Abstract  

A sorption ability of titanium silicates (TiSi) and iron oxides towards Cs, Sr, Pu and Am was tested using the laboratory batch method. The obtained results are expressed as distribution coefficients (Kd). TiSi synthesised using TiOSO4 revealed better sorption ability towards all studied radionuclides in comparison with TiSi produced on the basis of TiCl4. The Kd values ranged from 3.9 × 102 to 1.6 × 105 mL g−1 for Sr, from 6 to 4.1 × 104 mL g−1 for Cs, from 2.2 × 102 to 2.6 × 105 mL g−1 for Pu and from 50 to 1.6 × 104 mL g−1 for Am. The highest Pu Kd values (9 × 103–6.2 × 104 mL g−1) and better kinetics were found for iron oxides.

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