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Abstract  

A new approach for the characterization of coatings with respect to their corrosion protection is presented. The applicability of a simple in situ radiotracer method and some information which can be gained from sorption measurement of corrosive ions are demonstrated based on the results obtained in case of HSO4 /SO4 2– accumulation on a coating chosen. The technique used has low detection limit and the measurements can be performed without disturbing the primary experimental conditions.

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Abstract  

The radiotracer method was applied to evaluate the precision of themeasurements of abrasivity data obtained for dentifrice samples and for abrasiveagents (silica and calcium carbonate). This method consists of measuring 32P transferred to a dentifrice or abrasive slurry when an irradiated dentinis submitted to a brushing simulation. Results obtained for abrasivity indiceshad good precision with relative standard deviations lower than 11.8%. Comparisonsmade between our abrasivity index data with those obtained at the Oral HealthResearch Institute of Indiana University also showed a good agreement.

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Abstract  

Radiotracer method was developed for measuring14CO2 content in cement-wood mixtures. The carbon dioxide used for the treatment was labeled with14C, a -emitting radioisotope, and samples were measured by -scintillation and liquid scintillation techniques. Test samples were prepared in the laboratory with various compositions and treated with labeled14CO2. The tracer was released from Ba14CO3 by lactic acid with total activity of 37 MBq. Selectivity of the technique allows to distinguish the carbon dioxide bound during the treatment and bound previously from the mbient air. Sensitivity of the method is higher than that of traditional methods and allowed determination of CO2 content in each component of the mixture. It is 63 ng. if measured by -scintillation detector and 1.6 ng, if measured by liquid scintillation. Accuracy of the method is 0.3%.

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Abstract  

A new approach for the study of ion transport by an in situ radiotracer method is presented. The method is based upon the measurement of the intensity and energy spectrum change of -radiation during the penetration of labeled species. The applicability of the radiotracer technique is detailed through the measurement of the transport of labeled chloride ions into a PERMAPLEX-A20 anion exchanger membrane. The proposed method is applicable to in situ monitoring of the motion of ions in the membrane (or adsorbent).

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Abstract  

Application study for the evaluation of sorption characteristics of sawdust as an economical sorbent material used for decontamination of radioisotopes cesium and europium from aqueous solution has been carried out in the present work. In this respect, sawdust (untreated and treated by HNO3) has been prepared from the commercial processing of wood for furniture production. Pore properties of the activated carbon such as BET surface area, pore volume, pore size distribution, and pore diameter were characterized by N2 adsorption and DFT software. Radiotracer method onto sawdust from aqueous solutions was studied in a batch technique with respect to pH, contact time, temperature. The kinetics of adsorption of Eu3+ and Cs+ have been discussed using five kinetic models namely, pseudo-first-order model, pseudo-second-order model, Elovich equation, intraparticle diffusion model, and modified Freundlich equation that have been tested in order to analysis the experimental data. Kinetic parameters and correlation coefficients were determined. It was shown that the second-order kinetic equation could describe the sorption kinetics for two metal ions. The metal uptake process was found to be controlled by intraparticle diffusion. Thermodynamic parameters, such as ΔH, ΔG and ΔS, have been calculated by using the thermodynamic equilibrium coefficient obtained at different temperatures. The obtained results indicated that endothermic nature of sorption process for both 152+154Eu and 134Cs onto sawdust.

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Abstract  

Radiometric correction and interpolation methods have been worked out for rhenium determination with extraction of the tetraphenylphosphonium complex into dichloroethane. Liquid scintillation counting was used. The method allows to determine from 1 to 100 g of rhenium(VII) in analyzed probe. The relative standard deviation is 0.05–0.09 over the whole concentration range.

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Summary  

Modelingand experimental approaches to study reactive transport across chemical gradients in porous media are presented. Particular emphasis is placed on apurposeful experimental setup to obtain information necessary for model calibration and verification. As example, diffusion tube experiments on the layered acidic jarosite/alkaline coal fly ash system have been carried out using radiotracers 3H+, 22Na+, and 59Fe3+. Such radiotracer diffusion tube experiments provide modelers with reliable information incorporatingsome of the complexities observed in the environment such as local heterogeneities.

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Summary  

An efficient method for the isolation of iodine-accumulating bacteria was established. A total number of 138 bacterial strains were grown on agar media containing 125I, and the strains having strong radioactivity were chosen by autoradiography. They were then grown in liquid media containing 125I, and the radioactivity of the cells and the supernatants was determined after centrifugation through silicone oil. Eight strains were found to remove 78 to 90% of iodine from the media within 24 hours, and corresponding amount of iodine was detected in their cells. The advantage of this method is in its simplicity and the low detection limit.

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Abstract  

The fate of dissolved Hg(II) in surface waters is an important component of the Hg cycle. A simple experimental methodology was used to understand and measure the transport of Hg(II) from water to air and sediment. The use of radioactive dissolved Hg tracer for the determination of evasion and deposition is found to be a very useful technique. The evasion of mercury was investigated during a 140-hour period. It was observed that about a quarter of mercury chloride remained in the water phase, the other quarter was emitted via the evasion process and half of it deposited in sediment.

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Abstract  

The adsorption of RuCl3 and [Ru/NH3/5Cl]Cl2, [Ru/NH3/6]Cl3, Ru/III/EDTA complexes on polysulfur nitride, /SN/x, has been studied using radioactive103Ru. The values of the surface coverage show stronger in adsorption the [Ru/NH3/5Cl]Cl2 on /SN/x surface than the other studied ruthenium compounds. The perpendicular surfaces of /SN/x crystals are more active relative to the adsorption of the parallel surface.

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