Radiochemistry is a branch of chemistry that studies radioactive substances and chemical problems related to nuclear transformation processessubject。Radiochemistry and nuclear physics are correspondingly related and intertwined, becoming two brother disciplines of nuclear science and technology.
Major radiochemistry researchradioactivityPreparation, separation, purification and identification of nuclides and theirChemical state, the nature and behavior of nuclear transformation products, and the application of radionuclides in various disciplines.Since the 1960s, radiochemistry has mainly focused on the development, production and application of nuclear energy, as well as the accompanying environmental issues, and carried out basic, developmental and applied research.
Historical origin
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The development of radiochemistry in China began in 1924,Madame CurieOf Chinese studentsZheng DazhangSince Curie Laboratory of Paris Radium Research Institute brought back radiochemistry to China for the first timeNational Peiping Research InstituteChina's Radium Research Institute was established.Zheng DazhangEt al. studied protactinium andUranium seriesIn radiochemistry, preliminary achievements have been made.In 1937, due toJapanese MilitarismEncroachmentNorth ChinaThe Peiping Research Institute was forced to move southward, and the research work of radiochemistry was interrupted.
1949The People's Republic of ChinaSince its establishment, China's radiochemistry has made great progress.Since the mid-1950s, withnuclear energyThe development of radiochemistry as a disciplineBasic disciplineIt has been developed accordingly.For more than 30 years, especially aroundnuclear fuelProduction and recovery, preparation and application of radionuclides, actinide chemistryNuclear chemistry、radioactive wasteAnd its comprehensive utilizationRadioanalytical chemistryas well asRadiation chemistryAnd other fields have achieved fruitful results.October 1964Atomic bombAnd the successful test explosion of the hydrogen bomb in June 1967, reflecting that China's nuclear science and technology have reached a high level.
The name radiochemistry was proposed by Cameron in 1910.He pointed out that the task of radiochemistry is to study the chemical properties and attributes of radioactive elements and their decay products. This definition reflects the research object and content in the early development of radiochemistry.along withArtificial radioactivityandNuclear fissionThe discovery of, and the establishment of reactors and high-energy accelerators, have had a profound impact on the development of radiochemistry, enriching and developing the content of radiochemistry.
Major Research in Modern RadiochemistryNatural radioactive elementandArtificial radioactive elementThe chemical and nuclear properties of uranium, plutonium and thorium, and the chemical processes and processes for their extraction, preparation and purification,Transuranic elementAnd lobation elements;Study the nature, structure, nuclear reaction andNuclear decayAnd the application of these research results;To study the separation, analysis and nuclear technology of radioactive materialsanalytical chemistryApplication in;ResearchRadionuclideAndLabeling compoundAnd radiation source preparation, and its application in industry, agriculturescientific research, medicine and other fields.The focus is to use reactors and accelerators to produce various highSpecific activityOr carrier free radionuclides and radiation sources.
Physical and chemical properties
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Discipline characteristics
The object of radiochemistry is radioactive substances, which needs to make full use of modern technology to detect radioactivity, so it has many characteristics that are not available in general chemistry.
First of all, radiochemistry is extremely sensitive and can detect the mass of several atoms;The second is easy to identifyRadionuclideExcept can be ordinarychemical propertyIn addition to recognition, the unique properties of emitted particlesenergy、half lifeAnd the mother child relationship of decay;In addition, the characteristics of the chemical properties of radioactive materials and their stable isotopes can be used to track the trend of radioactive materials at any time and observe and study the relevant links in the chemical process.
radioactivityNuclear decayRadiatingenergyIt is far greater than the chemical binding energy of environmental substances, resulting in a series of radiation decomposition combination, radiation oxidation reduction, radiationcatalysisRadiation effects such as heating, luminescence and biochemical changes.In the highly radioactive system, the chemical changes caused by radiation effect are very significant.
In most radiochemical operations, the concentration of radionuclides is extremely low, and the charging property between ions is correspondingly prominent, which is easy to form radioactivitycolloidOr aerosol, dispersed or attached toEnvironmental chemistryPhysically.Therefore, the operation exceeds the national allowable doseRadioactive materialSpecial radiochemical techniques are required.
Protective measures
To prevent radioactive gas particles from entering the human bodyInternal exposureRadiochemical operation shall be carried out in the work box.Proper shielding shall be added inside and outside the box to make the radiationExternal exposureBelow the allowable dose;Special tools shall be used to reduce external exposure.If a manipulator is used instead of a direct hand contact and radioactive containerPipetteTransfer the solution, separate and precipitate with a centrifuge tube, and use quartz vessels that absorb less radioactive substances than glass.More attention should be paid to the explosive gas produced by the solution of highly radioactive substances or semi dry solids due to the radiation decomposition of water.
Discipline related
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Birth of discipline
1896RoentgenfindX-ray。Same yearBecquerelTo study the cause of fluorescence in the glass of X-ray tubeUranyl sulfateWhen potassium crystal is used as phosphor, it is found that the light-sensitive plate wrapped with black paper is sensitized by the action of uranium salt which does not emit light or dischargeMetallic uraniumIts photosensitive effect is the strongest.BecquerelIt is called uranium light, and thus discoveredRadioactive phenomenon。
1898Curie coupleIn order to find the source of radioactivity, a special instrument for measuring radioactivity was created to measure the radioactivity of various substances. It was found that some uranium minerals and thorium minerals are more radioactive than pure uranium or thorium. It is believed that these minerals contain very little but very strong radioactive substances.They use chemical analysisSeparation principlecombinationRadioactivity measurementPolonium and radium were discovered one after another, giving birth to a new discipline - radiochemistry.
Discipline development
1903rutherfordandSoddyDetermine the decay law of radioactivity of each material according to the exponential relationship.1910Soddy、FayansAt the same timeradioactive elementDisplacement rule, proposedisotopeThe concept of.1912HuvishHe used 20 chemical methods to try to separate radium D (i.e. lead 210) from lead, but failed. Then he proposed to use radium D to indicate lead, successfully studied the behavior of lead in various chemical reactions, and created the radioactiveTracer atomic methodApplied radiochemistry began to develop.
Small in 1934Curie coupleThe α particle of polonium is used to bombard aluminum, and the radioactive phosphorus 30 is obtained by chemical principles and methodsArtificial radioactivity。This is the first time that human beings use external influences to cause changes in atomic nuclei to generate radioactivity, and it is one of the most important inventions in the 20th century.In the same year, Zillate and others found that the atomic nucleus was being capturedneutronWhen a new radioactive nuclear cord is generated, a series ofChemical change, later developed intoThermal atomic chemistry。
Discipline contribution
In 1938, Hahn and others discovered and proved the phenomenon of uranium nuclear fission by chemical methods when studying the products of uranium irradiated by neutrons.It has opened the way for human beings to develop and use nuclear energy, which is a great contribution of radiochemistry to the development of nuclear science and technology.
1940MacmillanEtcTransuranic elementNeptunium;SiebergThey discovered plutonium and put forward the actinide element theory in 1944.1942FermiThe first building will be builtnuclear reactionNuclear reactor, the first time to realize controlled chain fission nuclear reaction, marks that mankind has entered the era of using nuclear energy, and nuclear science and technology have developed rapidly since then.
along withnuclear weapon, nuclear power plants, nuclear warships and other nuclear power plantsnuclear fuelProduction and recyclingFission productThe great development of radiochemistry, such as the separation of radioactive nuclides, has promoted the in-depth study of the properties of radioactive nuclides and their wide application in the fields of industry, agriculture, scientific research, medicine and health, enriched the content of radiochemistry, and made it a discipline with unique research purposes and methods.
