Ancient Rome and elementary particles
Scientists of NITU "MISIS" with the help of a new technology measured the number of micro impurities in the ingots of ancient lead from the sunken ship of the ancient Romans. It turned out that lead, which had lain for 1500 years under a layer of water, contains so few radioactive elements, uranium and thorium, that it can be used without any additional purification in one of the most “demanding” areas - nuclear physics - the study of elementary particles. The experiment on the isolation and determination of trace contaminants was conducted in collaboration with colleagues from the Joint Institute for Nuclear Research (Dubna) and the National Center for Scientific Research (France).
The more accurate and productive modern devices become, the more pure chemicals are required for their manufacture. These are the so-called “highly pure substances” (PTS) - which contain impurities in such a small amount that they do not affect the basic specific properties of the objects under study. One of the most "demanding" applications for ASH is experimental elementary particle physics. For example, charged particle accelerators, which are already built underground to protect against cosmic rays, still require additional radiation protection from special shields made of ultra-pure lead. One example of such accelerators is the Large Hadron Collider CERN.
Obtaining highly pure lead takes place in several stages, such as the dissolution of ore, smelting, separation of the alloy into its constituent parts, cleaning with alkali, alternating separation of each impurity substance. After a variety of purification steps, a sample of highly pure lead needs to be analyzed. The permissible maximum of impurities of radioactive elements should not exceed 0.0000000001% (one ten billion%) of the total mass. With this amount of radioactive impurities and lower lead can be used to protect high-precision instruments. However, even the most modern methods of direct elemental analysis do not allow determining such small amounts of impurities against the background of the main component, lead.
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Fragment of a lead ingot found in the frame of an ancient Roman ship off the coast of France
Scientists of the separation and concentration laboratory in chemical diagnostics of functional materials and environmental objects of NITU "MISiS" under the guidance of Dr. Sc. Peter Fedotov proposed a new way to separate impurities for their subsequent analysis. The experiment was conducted on samples of antique lead - ingots over 1500 years old. Once this lead was mined by the ancient Romans in the mines, located on the territory of modern England. During the transportation of lead ore, the ship sank and was discovered only at the end of the 20th century off the coast of France.
At the time of the experiment, this lead has been used by the National Center for Scientific Research (France) for several years as a highly pure substance - for one and a half thousand years a substantial part of uranium and thorium naturally disintegrated, and the water column protected lead ingots from the sticking of new radioactive impurities. Uranium and thorium were not detected in this lead, but it was assumed that the amount of impurities could simply be below the level of "visibility" of direct instrumental analysis, that is, below 0.00000001% (one hundred millionth%).
Then the scientists of NITU "MISiS" proposed their own method of separating impurities for subsequent analysis. Using the so-called planetary centrifuge and a system of two immiscible liquids (water and chloroform) containing special reagents, they first dissolved a sample of lead in highly pure nitric acid, and then isolated and concentrated the impurities.
Planetary centrifuge
Such a combined approach based on the separation of impurities and their subsequent determination allowed the scientists of NUST “MISiS” to determine the impurities of uranium and thorium with the required accuracy of 0.0000000001% (one ten billion%). However, the content of uranium and thorium was below this level. Thus, it turns out that antique lead, mined by the ancient Romans and raised from the day of the sea only after 1,500 years, is so pure that even with the most precise methods of separating and analyzing impurities, they cannot be seen and measured.
The scientists of NITU “MISiS” plan to use their new system of separation of impurities on a planetary centrifuge and continue to use it, mainly for the analysis of PMS.
Article published in the journal Talanta .
Photo RIA "News"
The more accurate and productive modern devices become, the more pure chemicals are required for their manufacture. These are the so-called “highly pure substances” (PTS) - which contain impurities in such a small amount that they do not affect the basic specific properties of the objects under study. One of the most "demanding" applications for ASH is experimental elementary particle physics. For example, charged particle accelerators, which are already built underground to protect against cosmic rays, still require additional radiation protection from special shields made of ultra-pure lead. One example of such accelerators is the Large Hadron Collider CERN.
Obtaining highly pure lead takes place in several stages, such as the dissolution of ore, smelting, separation of the alloy into its constituent parts, cleaning with alkali, alternating separation of each impurity substance. After a variety of purification steps, a sample of highly pure lead needs to be analyzed. The permissible maximum of impurities of radioactive elements should not exceed 0.0000000001% (one ten billion%) of the total mass. With this amount of radioactive impurities and lower lead can be used to protect high-precision instruments. However, even the most modern methods of direct elemental analysis do not allow determining such small amounts of impurities against the background of the main component, lead.
')
Fragment of a lead ingot found in the frame of an ancient Roman ship off the coast of France
Scientists of the separation and concentration laboratory in chemical diagnostics of functional materials and environmental objects of NITU "MISiS" under the guidance of Dr. Sc. Peter Fedotov proposed a new way to separate impurities for their subsequent analysis. The experiment was conducted on samples of antique lead - ingots over 1500 years old. Once this lead was mined by the ancient Romans in the mines, located on the territory of modern England. During the transportation of lead ore, the ship sank and was discovered only at the end of the 20th century off the coast of France.
At the time of the experiment, this lead has been used by the National Center for Scientific Research (France) for several years as a highly pure substance - for one and a half thousand years a substantial part of uranium and thorium naturally disintegrated, and the water column protected lead ingots from the sticking of new radioactive impurities. Uranium and thorium were not detected in this lead, but it was assumed that the amount of impurities could simply be below the level of "visibility" of direct instrumental analysis, that is, below 0.00000001% (one hundred millionth%).
Then the scientists of NITU "MISiS" proposed their own method of separating impurities for subsequent analysis. Using the so-called planetary centrifuge and a system of two immiscible liquids (water and chloroform) containing special reagents, they first dissolved a sample of lead in highly pure nitric acid, and then isolated and concentrated the impurities.
Planetary centrifuge
Such a combined approach based on the separation of impurities and their subsequent determination allowed the scientists of NUST “MISiS” to determine the impurities of uranium and thorium with the required accuracy of 0.0000000001% (one ten billion%). However, the content of uranium and thorium was below this level. Thus, it turns out that antique lead, mined by the ancient Romans and raised from the day of the sea only after 1,500 years, is so pure that even with the most precise methods of separating and analyzing impurities, they cannot be seen and measured.
The scientists of NITU “MISiS” plan to use their new system of separation of impurities on a planetary centrifuge and continue to use it, mainly for the analysis of PMS.
“Among the advantages of the technology proposed by us is its“ flexibility ”: depending on the impurities of which elements need to be separated, a variety of reagents and immiscible liquid phases can be used. Thus, it is possible to separate, concentrate, and analyze the smallest ultra-trace impurities to determine the "high purity" of substances, ”says the head of the study, Peter Fedotov.In addition, potentially with large volumes of the separation column of a planetary centrifuge, it is also possible to purify substances by dissolving them and driving them through the impurity separation cycle.
Article published in the journal Talanta .
Photo RIA "News"
Source: https://habr.com/ru/post/457306/
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