Thorium radioactivity experiments

In 1898 Marie Sklodowska Curie (1867-1934), while experimenting with thorium and uranium, coined the word radioactivity to describe this newly discovered type of radiation. She went on to discover polonium and radium. Madam Curie and her husband Pierre Curie (1859—1906), who discovered the piezoelectric effect, which is used to measure the level of radiation, and Henri Becquerel jointly received the 1903 Nobel Prize in Physics for their work on radioactivity. 

It is of considerable interest to note that charge clusters can be formed in aqueous solutions and used to target dissolved radioactive materials. In experiments using low-level, naturally radioactive thorium, a considerable reduction of thorium from the solution has been achieved [6]. Charge clusters can be produced in air under various pressures [23]. However, not all arcs and sparks... 

Before Rutherford left the Cavendish Laboratory he had taken active part in the many discussions over the work of Becquerel, Roentgen, and the Curies. Here was a virgin field full of possibilities. He chose it, and began working with uranium and thorium, a kindred element. By 1900, he had already noticed a peculiar phenomenon in connection with the latter substance. It gave off a minute amount of a gas very rich in radioactivity. He carried out precise experiments to determine the nature of the gas and found, to his astonishment, that it was a hitherto unknown substance. He named this gas thorium emanation. ... 

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. 

Soon after Becquerel s discovery of uranium s radioactivity, Marie Sklodowska Curie (1867—1934), also working in France, studied the radioactivity of thorium (Th) and began to search systematically for new radioactive elements. She showed that the radioactivity of uranium was an atomic property— that is, its radioactivity was proportional to the amount of the element present and was not related to any particular compound. Her experiments indicated that other radioactive elements were probably also present in certain uranium samples. With painstaking technique, she and her husband Pierre Curie (1859-1906) separated the element radium (Ra) from uranium ore and found that it is more than one million times more radioactive than uranium. In 1903, Marie and Pierre Curie shared the Nobel Prize in physics with Henri Becquerel for their discovery of radioactivity. After Pierre died. 

Another strand of development came from several attempts to separate some of these new radio-elements chemically, which ended in failure. First of all, in 1907 Herbert McCoy and WiUiam Ross concluded that, in the case of thorium and radiothorium, Our experiments strongly indicate that radiothorium is entirely inseparable from thorium by chemical processes, " a comment Soddy considered the first definitive statement of the chemical inseparability of what were soon to be called isotopes. Soddy himself wrote in the same year that there seemed to be no known method of separating thorium X from mesothorium.They were in fact two isotopes of thorium. Similar cases began to multiply. Bertram Boltwood discovered the radio-element ionium, which could not be chemically separated from thorium. In another famous case, Hevesy and Paneth were asked by Rutherford to try to separate radio-lead from ordinary lead and likewise failed to do so, in spite of using 20 different chemical methods. Their work was not entirely in vain, however, since it led to the development of the use of radioactive tracers, which have become an indispensable tool in modem chemistry and biochemistry. 

It is concluded from this review that measurements of Bi-212, Tl-208 and Pb-212 all give consistent estimates of Th-232 by y-spectrometry and Ra-224 does not. Experience is that Pb-212 is detected with the highest reliability. The mean value Th-232 at Dounreay, assumed to be in equilibrium with Pb-212, is 0.027 Bq/g, which exceeds the threshold of radioactive waste unless the material is natural. The value is within the range reported above for natural soils. Although there are no features of the decay chain that would allow manufactured thorium materials to be separated from natural materials since secular equilibrium is re-established so rapidly, because pure thorium has a specific activity of 4100 Bq/g, activity concentrations alone will distinguish such material. 

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