But now the salt at home has been dry for a while. Because I study chemistry.
Until one day I saw such a title: mysterious anti-caking agent in salt!
Anti-caking agent, a substance added to granular and powdery foods, is used to prevent them from gathering and caking, and to keep them loose or free flowing. Potassium (sodium) ferrocyanide, sodium aluminosilicate, ammonium ferric citrate, tricalcium phosphate, silicon dioxide, calcium silicate and microcrystalline cellulose are allowed to be used in China.
? According to China's national standards, the content of anti-caking agent added in salt should not exceed 10 mg/kg, taking ferrocyanide as an example.
? Potassium ferrocyanide is also called potassium ferrocyanide, and its molecular formula is K4fe (CN) 6 3H2O. It is light yellow single italic crystal or powder, odorless and slightly salty, and its relative density is 1.85. It is stable at room temperature. When heated to 70℃, it began to lose its crystal water, and when heated to 100℃, it completely lost its crystal water and became hygroscopic white powder. Decomposition occurs at 400℃, releasing nitrogen to produce potassium cyanide and iron carbide. Soluble in water, insoluble in ethanol, ether, methyl acetate and liquid ammonia. Its aqueous solution is decomposed into iron hydroxide when exposed to light, and the iron hydroxide reacts with excess Fe3+ to generate Prussian blue pigment. Toxic potassium ferrocyanide is extremely toxic because the cyanide ion in the molecule is firmly combined with iron.
Potassium hexacyanoferrate
prussian blue
? Salt is easy to harden when it is piled up for a long time. After adding potassium ferrocyanide, the regular hexahedral crystals of salt are transformed into star crystals, which are not easy to agglomerate. (No specific reason for crystal change was found)
According to the evaluation data of the expert committee of the World Health Organization and the International Food and Agriculture Organization, for potassium ferrocyanide to have adverse effects on human health, adults should take at least 1.5mg per day.
According to the standards of our country, it is equivalent to eating about three ounces of salt every day (150g, which is equivalent to one third of a bag), and if we normal people can eat 20g of salt every day, our bodies will already be unbearable salty.
? Containing cyanide ion, why is the toxicity so low? because ...
Their love binding index (cumulative compound equilibrium constant) is the 35th power of 10. Have a certificate! As shown below.
? Potassium ferrocyanide decomposes at 400℃, releasing nitrogen to produce potassium cyanide and iron carbide. The general cooking temperature will not reach such a high temperature, because at this high temperature, the oil has been charred and carbonized, and the vegetables must turn into charcoal!
? But if it's dry fried salt on the street or fried chestnuts with sand, that's another matter!
According to the reversibility of the reaction, the aqueous solution of potassium ferrocyanide can react with acid to produce highly toxic hydrogen cyanide (HCN). If it reacts with vinegar or stomach acid, it will definitely produce hydrogen cyanide. Will you die? ! I found the following explanation: the human body also has the natural ability to detoxify CN ions, and the detoxification speed is about 5mg CN ions per hour. You may ingest cyanide ions through salt in one day, and it only takes 2 minutes to detoxify automatically. Finally, vitamin B 12 is an excellent antidote for cyanide. The VB 12 contained in an egg can treat cyanide ions ingested through salt for at least 5 days.
I found myself caught in a similar rumor: the conspiracy theory of adding potassium iodate to salt.
In medical treatment, thallium can replace the iron in Prussian blue to form insoluble substances, which are excreted with feces, and have certain curative effect on oral acute and chronic thallium poisoning. The dosage is generally 250mg/kg daily, divided into 4 times, dissolved in 50 ml 15% mannitol for oral administration.
(Appropriate potassium chloride supplementation? High potassium can increase the clearance rate of thallium in kidney, which may be related to the competitive blocking of thallium absorption by renal tubules by potassium. At the same time, potassium can mobilize thallium from cells to cells, increase the content of thallium in blood and aggravate the clinical condition, so it should be used with caution. )