What Is Iodine 131?

Iodine-131 is a radioactive isotope of elemental iodine. It is an artificial radionuclide (nuclear fission product) with the symbol I-131 and a half-life of 8.04 days. Under normal circumstances, nature does not exist.

Iodine 131

Iodine-131 is a radioactive isotope of elemental iodine. It is an artificial radionuclide (nuclear fission product) with the symbol I-131.

Iodine mass	Physical half-life
123	13.2 hours
125	60 days
129	1.9 century 7 years
131	8.04 days
132	2.28 hours
133	20.3 hours
134	52.5 minutes
135	6.8 hours

A radioactive isotope of iodine-131. The symbol I-131 is abbreviated as I. Its nucleus has 78 neutrons, while the stable iodine of iodine has only 74 neutrons.

The nuclear reactions that produce iodine 131 are:

Use tellurium or its compound (such as tellurium dioxide) as the target material, irradiate it in the reactor, generate tellurium 131 through (n, ) reaction, and then tellurium 131 undergoes decay to obtain iodine 131, namely Te (n, ) TeI;

Using enriched uranium 235 as a target material, iodine 131 is obtained by nuclear fission U (n, f) I or U (n, f) TeI, and the total fission yield of iodine 131 is about 0.82%.

Method can obtain relatively pure products without alpha impurities and other fission products. This method is used in many countries in the world. When using method to prepare iodine 131, in addition to possible pollution of other radioactive iodine isotopes, there is also alpha Impurities and beta impurities must be effectively purified and used in only a few countries.

extract

The methods for extracting iodine 131 from the target material tellurium dioxide include dry distillation, chromatography, extraction and distillation, and the more commonly used are dry distillation and distillation. The distillation method is to dissolve the irradiated tellurium dioxide in a sodium hydroxide solution, add hydrogen peroxide, a molybdenum salt, etc., and then perform distillation in a sulfuric acid medium. The fraction containing iodine 131 was absorbed with sodium hydroxide added with a reducing agent, and iodine 131 was obtained as a NaI solution. NaI solution is the primary product of iodine 131.

Production protection

When mass production of iodine 131, care should be taken to avoid volatilization of iodine 131, so as not to cause serious pollution to the environment. The operation should be carried out in a shielded box room with negative pressure and with an iodine removal device. Activated carbon, silver-coated activated carbon, silver-copper alloy mesh, silver mesh, and alkaline solutions are all good adsorbents for iodine 131.

use

In nuclear medicine, in addition to being directly used as a NaI solution for thyroid function tests and thyroid disease treatment, iodine 131 can also be used to label many compounds for in vivo or in vitro diagnosis of diseases. For example, iodine 131 labeled rose red sodium salt and sodium urate are common scanning imaging agents for liver, gallbladder and kidney. In addition to nuclear medicine applications, iodine 131 can also be used to find groundwater, measure the flow rate and direction of groundwater, and find underground pipeline leaks; determine the water absorption capacity and changes of oil layers in oilfield injection wells in order to take timely and effective measures to regulate the Distribution, and maintain high and stable production of oil wells.

Radioactive iodine found in Heilongjiang Province

1. Iodine [131I] has no adverse reactions in most patients after treatment of hyperthyroidism, and a few have mild reactions such as fatigue, loss of appetite, and nausea within a week, which usually disappear within a few days. After taking iodine [131I], the radiation destroys the thyroid tissue and releases a large amount of thyroid hormones into the blood. About 2 weeks after taking iodine [131I], the symptoms of hyperthyroidism may increase, and some patients even have it.

Hyperthyroidism is an endocrine disease caused by excessive secretion of thyroid hormones. Iodine is an important raw material for the production of thyroid hormones. Therefore, patients with hyperthyroidism should especially avoid iodine. So what are the disadvantages of iodine to hyperthyroidism?

First, iodine is the main raw material for the production of thyroid hormones. Excessive intake of iodine can lead to exacerbation of hyperthyroidism and even iodine-induced hyperthyroidism.

Second, too much iodine may harden the thyroid tissue, affect thyroid drug treatment, and cause the disease to be cured for a long time. Excessive iodine makes prolonged thyroid drug treatment time and cure rate decrease. After overiodine supplementation, the cure for antithyroid drugs for hyperthyroidism drops to 20% to 35%.

Therefore, patients with hyperthyroidism should consume as little iodine as possible, especially seafood rich in iodine, such as kelp, seaweed, sea fish and other foods, and Chinese medicines containing iodine, such as seaweed, kelp, etc. should be banned. Salt should be consumed without iodine.