Thorium percentage

A very small percentage of injected thorium-232 dioxide (Thorotrast) in humans was excreted (more in the feces than urine) (Kaul and Muth 1978 Molla 1975). Jee et al. (1967) found that a patient excreted 0.7% of the injected amount of Thorotrast in the 17 days between injection and the death of the patient (mode of excretion not reported). Kemmer (1979) determined that the amount of thoron (radon-220) exhaled by the lungs in humans correlated to the amount of Thorotrast intravenously injected. The thoron (radon-220) correlated with a "radium-224 equivalent value."... 

In contrast to the thorium from Thorotrast (a thorium dioxide and dextran suspension) after intravenous injection, a higher percentage of thorium from more soluble thorium compounds is excreted. Following intravenous injection of thorium-234 citrate in humans, there is a relatively rapid but small (7%) amount of excretion within the first 20 days. A urine/feces ratio of 12 for male subjects and 24 for female subjects was determined. About 93% of the injected thorium-234 was retained at 100 days after injection, with a biological half-time of more than 5 years (Maletskos et al. 1969). 

E. B. Maxted found that the percentage conversion with iron catalyst activated with the promotors copper, thorium, tungsten, cerium, or bismuth, at 700°, when the time of contact of the gas-mixture with the catalyst is 0-015 sec., is as follows, when iron alone gave 83-5 per cent, conversion ... 

Percentage of Extraction ( %) of Europium and Thorium Nitrates from 1 M HNO. into Dichloromethane Containing the Ligand at Various Concentrations... 

Percentage Extraction, % , and, in Brackets, Distribution Ratios, D, for Lanthanides and Thorium Nitrates by Narrow-Rim Calixarenes CMPO from 1 M HN03 into Dichloromethane T = 20°C, CM = 10 4 M... 

The latter assumption is now seen to be extremely doubtful for,the varying atomic weights prove that more than one kind of lead must be considered. Thorium lead especially must be taken into account, for many uraninites contain it, and in thorianite the percentage of thoria is more than five times that of uranium oxide. The ratio of lead to its parent elements is therefore much less than Boltwood assumed, and the calculated age of thorianite is vastly reduced. Boltwood, however, doubted the derivation of lead from thorium, a fact which was not definitely known at the time his paper was written. The evidence of the atomic weights is also much later. 

A sample of pure (NH4)2Ce(N03)g indicates a purity (for cerium) of 99.98% when it reacts with primary standard arsenic(III). Examination of the (NH4)2 Ce(N03)g by emission spectroscopy indicates that it contains 0.06% of the element thorium [presumably as (NH4)2Th(N03)e]. Such results can be rationalized by assuming a deficiency of NH3 and that the sample contains H2Ce(N03)6. (a) What is the percentage of the theoretical cerium content (6) Calculate the percentage of H2Ce(N03)e in the sample, (c) Calculate the percentage of the theoretical NH3 content. 

A 20.0 g sample of thorium-234 has a half-life of 25 days. How much will remain as a percentage of the original sample after 90 days ... 

The percentage of thorium and other constituents of the monazite sand recovered in the precipitate is given in the first column of Table 6.17. The composition of the precipitate is given in the second column. 

B. Increasing amounts of thorium oxide, increasing amounts of unreduced cobalt, and traces of alkali increase the percentage of higher hydrocarbons. 

In addition, it should be noted that, although the generic formula of some minerals listed in Table XII-1 does not mention thorium, this element is often present in such minerals by snbstitution for quadrivalent or tervalent species, in percentages that may be in excess of 10%. This is, for instance, the case for Sm-monazites. Of course, in such substitutions charge balance must be maintained and the replacement of a tervalent ion by thorinm mnst be accompanied by an equivalent increased amount of a lower-valent cation (often Ca ) in the stmctnre. 

Removal of Radioisotopes Some data also exists for the removal of the radioactive element thorium (Th) by nanomaterials. The experiment utilizing Ti02 nanoparticles to remediate Th(IV) contamination was conducted specifically with contaminated soils. Experiments conducted in the presence or absence of soil humic acid and fulvic acid demonstrated that both the fulvic and humic acids increased the sorption of Th(lV) to Ti02 nanoparticles at acidic pH (90). Bare Ti02 nanoparticles by themselves were able to form surface complexes with 94% of the available Th(IV) this percentage increased to 97%-98% in the presence of fulvic or humic acids and remained stable with increasing pH. This technique could be utilized to remediate soils contaminated with Th(TV), and in fact would likely be more effective in soils than in water. 

Curie examined all the known elements and found that, apart from uranium, only thorium appeared to emit ionising radiation. All compounds of these elements were active, and changing the temperature had no effect on the activity. The new property, which Curie named radioactivity, appeared to be an atomic phenomenon, because the intensity of the radiation emitted by a uranium compound was found to be proportional to the percentage of uranium it contained. 

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