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CAS Number: 13821-08-4
EC Number: 237-508-9
E number: E538 (acidity regulators)
Chemical formula: C6Ca2FeN6
Molar mass: 292.109 g·mol−1


E538 (Calcium ferrocyanide) is used as anti-caking agent.
Because of the strong chemical bond between iron and the cyanide groups, E538 (Calcium ferrocyanide) has a low toxicity. 
Sodium ferrocyanide (E 535), potassium ferrocyanide (E 536) and E538 (Calcium ferrocyanide) are permitted in salt and its substitutes at the level of 20 mg/kg (calculated as anhydrous potassium ferrocyanide) individually or in combination.
E538 (Calcium ferrocyanide) is Used to remove metallic impurities from citric, tartaric, and other acids.

E538 (Calcium ferrocyanide) is used to remove metallic impurities from tartaric, citric, and other acids. 
Also E538 (Calcium ferrocyanide) is used as a stabilizer for the coating on welding rods, and fertilizer for plants. 
Other applications of E538 (Calcium ferrocyanide) include removal of mercaptans in the petroleum industry; production of wine and citric acid; fixing, toning, and bleaching in photography; separation of copper from molybdenum ores and purification of tin; and anti-caking agent for both table salt and road salt. 

In the past, E538 (Calcium ferrocyanide) was produced from organically derived nitrogenous carbon sources, potassium carbonate, and iron filings. 
Historically, common carbon and nitrogen sources were offal, leather scrap, dried blood, or torrified horn. 
The global E538 (Calcium ferrocyanide) market is growing at a significant growth over the forecast period, owing to rapid growth of anti-caking in pharmaceutical industry. The Asia-Pacific E538 (Calcium ferrocyanide) market accounts for relatively high revenue share, followed by North America E538 (Calcium ferrocyanide) market, attributed high demand of fertilizers in agriculture.

Anti-caking Agent - E538 (Calcium ferrocyanide) Prevents lumps from forming in food due to excess water. 
They usually function as a water repellent or by absorbing excess moisture.
E538 (Calcium ferrocyanide) is prepared from hydrogen ferrocyanide and calcium hydroxide. 
E538 (Calcium ferrocyanide) is an anti-caking agent used in producing table salt, which can keep the salt from clumping so that it pours out of the saltshaker with greater ease. 

E538 (Calcium ferrocyanide) is an approved food additive in EU with E number 538.
In food manufacture, E538 (Calcium ferrocyanide) is used as an anti-caking agent.
E538 (Calcium ferrocyanide) is prepared from hydrogen ferrocyanide and calcium hydroxide.
E538 (Calcium ferrocyanide) is used as anti-caking agent in food industry.

E538 (Calcium ferrocyanide), whether in food grade or industrial form, has a wide range of uses in a variety of sectors. 
In the manufacturing industry, E538 (Calcium ferrocyanide) is employed on a wider scale. 
E538 (Calcium ferrocyanide) is widely utilised in the manufacturing industry for a variety of purposes, including as a stabilising chemical and a separating agent.

Based on the end-use, the global E538 (Calcium ferrocyanide) market is segmented into:

-Food Products
-Agricultural products
-Pharmaceutical Products
-Wine Production
-Welding Rods

Based on the application, the global E538 (Calcium ferrocyanide) market is segmented into:

-Anti-caking Agent


E538 (Calcium ferrocyanide) is an inorganic compound with the formula Ca2[Fe(CN)6]. 
E538 (Calcium ferrocyanide) is the Ca2+ salt of [Fe(CN)6]4-, ferrocyanide complex ion. 
A yellow solid, E538 (Calcium ferrocyanide) is used as a precursor to the pigment Prussian blue.
E538 (Calcium ferrocyanide) belongs to the class of organic compounds known as transition metal cyanide salts. 
These are organic compounds containing a transition metal and a cyanide ion [C-]#N.

E538 (Calcium ferrocyanide) is an inorganic metallic compound produce from the ferrous chloride, hydrogen cyanide, and calcium hydroxide. 
E538 (Calcium ferrocyanide) is odorless, yellow crystalline granules which are soluble in water. 
Also, E538 (Calcium ferrocyanide) is known by the common name yellow prussiate of lime with INS No. Calcium salt E538. 
E538 (Calcium ferrocyanide) is also known as Dicalcium hexacyanoferrate or Calcium hexacyanoferrate. 

E538 (Calcium ferrocyanide) is Yellow crystals soluble in water. 


Recrystallise it three times from conductivity H2O and dry it in air to constant weight over the partially dehydrated salt. 
Alternatively the Ca salt can be purified by precipitation with absolute EtOH in the cold (to avoid oxidation) from an air-free saturated aqueous solution. 
The pure lemon yellow crystals are centrifuged, dried in a vacuum desiccator first over dry charcoal for 24hours, then over partly dehydrated salt and stored in a dark glass stoppered bottle.

No deterioration occurred after 18 months. 
No trace of Na, K or NH4 ions could be detected in the salt from the residue after decomposition of the salt with conc H2SO4. 
Analyses indicate 11mols of H2O per mol of salt. 
The solubility in H2O is 36.45g (24.9o) and 64.7g (44.7o) per 100g of solution. 


E538 (Calcium ferrocyanide) was listed in 2012 by the EU as a "Food Improvement Agent".
In the EU, ferrocyanides (E 535–538) were, as of 2018, solely authorised in two food categories as salt substitutes. 
Kidneys are the organ for ferrocyanide toxicity.


Dicalcium hexakis(cyano-κC)ferrate(4-)
E538 (Calcium ferrocyanide)

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