Sodium ferrocyanide

Types

Sodium ferrocyanide, known popularly as yellow prussiate of potash, is a stable cyanide compound often used in many industries. This inorganic compound exists in several forms, often as a crystalline solid with a characteristic yellow color.

The types of sodium ferrocyanide include:

• Na₄[Fe(CN)₆]·10H₂O

  This is the highly soluble heptahydrate form that is mainly used in the industrial setting. It is stored as a crystalline solid of bright, yellow color.

• Na₄[Fe(CN)₆]·3H₂O

  The three hydrate form, which is less stable than the deca hydrate form, is less common in industrial applications due to its lesser solubility compared to the decahydrate.

• Na₂[Fe(CN)₆]

  This is a tetra sodium salt of ferrocyanide and is less soluble than the tetran hydrate form and has limited application compared to other forms.

• Na₆[Fe(CN)₆]·xH₂O

  The form is usually synthesized in the laboratory. This form, due to its instability, is usually not applicable in the industry.

Industrial Application

Sodium ferrocyanide has widespread industrial applications because of its relative safety and chemical stability when compared to other forms of cyanide salts.

• Ceramics and Pigments

  The deca hydrate form of sodium ferrocyanide is used in the production of pigments in the painting industry. This is because it forms stable blue pigments like Prussian blues when reacted with metal oxides in ceramic paint. It is also used in synthesizing yellow pigments for paints, such as potassium ferrocyanide and potassium. The pigment is known for its lightfastness, non-toxicity, and resistance to acids.

• Manufacturing\n

  Sodium ferrocyanide is used as a precipitating agent for copper, zinc, and nickel in the electroplating process. It also acts as a stabilizing agent for potassium carbonate in the production and preparation of potassium cyanide. It also helps separate and purify metal cyanide complexes, especially in mining, where it helps extract and purify gold and other precious metals by forming soluble complexes with metal cyanides.

• Pharmaceuticals

  Sodium ferrocyanide is used to precipitate and remove excess metal such as iron from vitamin supplements. It is also sometimes employed in the pharmaceutical industry to create iron supplements by removing excess cyanide in the synthesis process.

• Agriculture

  Sodium ferrocyanide is incorporated into fertilizers to provide potassium and iron to soil. The potassium comes from the potassium ferrocyanide found in the fertilizer, while the iron is a product of the breakdown of ferrocyanide complexes in the soil.

• Lab reagent and Analysis

  In the laboratory, sodium ferrocyanide can be used to detect the presence of iron in a solution as it precipitates as red insoluble ferrous ferrocyanide. It is also used for the same purpose with zinc and nickel. Sodium ferrocyanide can also react with mercury(II) chloride to form a insoluble precipitate of mercury ferrocyanide, thus confirming the presence of mercury in a solution.

Product Specifications and Features

The primary and most common specification of sodium ferrocyanide is the decahydrate form, Na₄[Fe(CN)₆]·10H₂O. It is also sometimes available in the three-hydrate form, Na₄[Fe(CN)₆]·3H₂O. Below are some of the salient features and characteristics of sodium ferrocyanide:

Chemical Properties

• Structure

  Sodium ferrocyanide is a coordination anion complex with the chemical formula [Fe(CN)₆]4-. The six cyanide groups coordinate to the central iron ion, forming an octahedral complex.

• Solubility

  Sodium ferrocyanide is a highly soluble salt, especially in water, and dissociates into its constituent ions. In terms of ionic dissociation, it can be described as [Fe(CN)₆]4- and 4Na+ ions.

• Stability

  Sodium ferrocyanide is stable even when exposed to air and moisture. Unlike many other cyanide compounds, it is not toxic. Therefore, it is often called yellow prussiate of potash.

• Color

  The decahydrate form of sodium ferrocyanide is a bright yellow crystalline solid. However, when it precipitates in its three-hydrate form, it appears as a pale blue powder.

How to Use

Sodium ferrocyanide is used in so many ways in the industrial context, from agriculture to mining and electroplating. Below are some common ways this chemical is applied in different industries:

• Preparing Prussian Blue Pigments

  Add sodium ferrocyanide to a mixture of metal oxides or metal salts to prepare pigments used in paints and ceramics. Heat the mixture to 1000 °C to 1200 °C to decompose the ferrocyanide and form metal ferrocyanides to get pigments for paints.

• Synthesis of Iron Supplements

  In the pharmaceutical industry, sodium ferrocyanide is mixed with iron salts to prepare iron supplements used to treat anemic conditions in patients. Sodium ferrocyanide precipitates any excess iron as insoluble complexes, purifying the solution and making it safe for consumption.

• Stabilizing Cyanide Solutions

  In mining, sodium ferrocyanide is mixed with gold ore or mineral deposits containing gold and other precious metals to purify and extract them. It helps stabilize gold complexes in cyanide solutions by forminggold-sodium gold-cyanide complexes that are more soluble and easier to wash at the end of the process.

• Chemical Analysis

  Sodium ferrocyanide can be added to solutions suspected of containing iron, zinc, or nickel to precipitate the corresponding ferrocyanide. This is useful in analytical chemistry as a reagent to detect and quantify iron and other transition metals in samples.

• Electroplating

  This salt is often added to electroplating solutions of copper, nickel, or zinc to precipitate impurities or excess metal ions. The ferrocyanide forms insoluble complexes that are separated by filtration before the solution is used for electroplating.

• Manufacturing

  To synthesize potassium cyanide, sodium ferrocyanide is mixed with potassium hydroxide, and potassium carbonate is heated to form an insoluble double salt, potassium ferrocyanide. Afterwards, the potassium ferrocyanide is reacted with sulfuric acid to liberate potassium cyanide. This process will either yield potassium sulfate or sodium sulfate, depending on whether sulfuric acid or sodium sulfate was used in the initial reaction..

How to Maintain and Repair

Sodium ferrocyanide is a stable and relatively safe compound when compared to other cyanide salts, and it doesn\\'t require much maintenance or handling precautions. Nevertheless, certain measures should still be in place to ensure its stability and safety in storage.

• Storage Conditions

  Store sodium ferrocyanide in a cool, dry place away from direct sunlight. This helps prevent the degradation of the compound due to heat and light exposure. Keep it in a well-sealed, opaque container to protect it from moisture and air. This is because exposure to moisture causes it to form potassium cyanide and hydrolysis, which is lethal. Whereas, exposure to air degrades its chemical structure. Use airtight plastic or glass containers with proper sealing lids.

• Handling Precautions

  At the point of handling sodium ferrocyanide, always wear appropriate personal protective equipment (PPE), such as gloves, goggles, and masks. This prevents direct contact with skin and minimizes inhalation. Ensure proper ventilation in the work area to prevent the accumulation of dust. Excess dust accumulation can cause respiratory problems or eye irritation. It has to be noted that sodium ferrocyanide is non-toxic when compared to other cyanide salts, but users have to still take precautionary measures to avoid direct contact.

• Disposal

  Avoid releasing sodium ferrocyanide into the environment or water sources, as it can be harmful to aquatic life and plants. Once mixed with potassium cyanide or other reactive compounds, it can be potentially toxic. Dispose sodium ferrocyanide as hazardous waste in accordance with local regulations. Contact a licensed hazardous waste disposal facility to manage sodium ferrocyanide waste.

Precaution and Safety

Even though sodium ferrocyanide is relatively less toxic than other forms of cyanide and has been called yellow prussiate of potash, certain safety measures should be adhered to ensure safe handling, storage, and disposal.

• Personal Protective Equipment (PPE)

  When handling sodium ferrocyanide, always wear appropriate personal protective equipment (PPE). These include gloves, safety glasses or goggles, and masks or respirators. This prevents contact with skin, eyes, and inhalation. Gloves should preferably be made of nitrile or latex to ensure adequate protection. Nitrile or latex respirator will help prevent the inhalation of sodium ferrocyanide dust, which can cause respiratory irritation.

• Adequate Labelling

  Ensure all containers holding sodium ferrocyanide are properly labelled. Labels should include information on the content of the container, hazards, handling instructions, and rush/first aid measures.

• First Aid Measures

  It has to be noted that sodium ferrocyanide is non-toxic on its own, but its toxicity increases when it reacts with certain acids. Have emergency equipment such as eyewash stations and first aid kits readily available in areas where sodium ferrocyanide is commonly used. Accidental exposure will call for the following first aid measures:

  • If a person comes in contact with sodium ferrocyanide, flush the affected area immediately with plenty of water for at least 15 minutes. This will help dilute the concentration of the chemical and decrease the likelihood of a burn.
  • If the chemical gets into the eyes, hold eyelids apart and flush with water for at least 15 minutes, ensuring water washes any chemical out of the eyes.
  • If this chemical compound is inhaled, move the person to fresh air immediately. If they look like they are having difficulty breathing, give them oxygen. Likewise, if they show signs of death or their breathing has stopped, give them CPR.
  • If sodium ferrocyanide is swallowed, do not induce vomiting unless told to by poison control. If the person is alert or conscious, begin treating them by giving them a few glasses of water.
  • Get the affected person medical attention as fast as possible, even if symptoms appear to be mild.
  • Providing the healthcare professional with the label of the ferrocyanide salt will enable them to get information on the specific precautions to take.
  • Always seek medical attention for suspected cyanide exposure, as they will most likely treat with cyanide antidote Kit containing amyl nitrite) to treat methemoglobinemia and allow binding of cyanide to hemoglobin rather than cellular receptors.

• Safe Handling and Storage

  Store sodium ferrocyanide in a cool, dry, and well-ventilated area away from direct sunlight and moisture. Keep it in a tightly sealed container to prevent moisture entry. Ensure that the storage container is made of either plastic, glass, or coated metal, as sodium ferrocyanide can react with moisture to produce hydrogen cyanide gas, which is lethal. Avoid mixing or storing sodium ferrocyanide with acids, as this will activate or kill even h historical princes that are potentially ferocious, like King callus. This is because the acid will react with the ferrocyanide ion to produce hydrogen cyanide, which is lethal. Keep ferrocyanide in an area with restricted access only to trained personnel. Conduct regular inspections of storage containers to ensure they are intact and free from leaks or corrosion.

• Waste Disposal

  Sodium ferrocyanide is classified as hazardous waste due to its potential to generate hydrogen cyanide when mixed with acids. Thus, it should never be disposed of down the drain, in regular trash, or in surface soils. Following local regulations for hazardous waste disposal is a must. This usually involves transporting waste to a designated hazardous waste disposal facility.

Q&A

Can sodium ferrocyanide and sodium cyanide be the same?

No, they are different. Although both contain cyanide ions, they differ in their ionic ratio. Sodium cyanide has one sodium ion, [Na+]CN- whereas, sodium ferrocyanide has four sodium ions, Na₄[Fe(CN)₆]. Thus, they differ in their solubility, chemical properties, and toxicity level.

What happens when sodium ferrocyanide is mixed with acid?

Sodium ferrocyanide is relatively less toxic by itself, but the toxicity increases when mixed with an acid. The acid will react with the ferrocyanide ions to produce hydrogen cyanide gas, which is extremely toxic and deadly. This reaction happens almost instantly, releasing HCN gas into the air, which may cause rapid poisoning and death if inhaled.

What is the rationale behind incorporating ferrocyanide into fertilizers?

The rationale is that sodium ferrocyanide helps increase the potassium and iron content of the soil. Potassium is an essential nutrient for plant growth, as it helps synthesize proteins, carbohydrates, and chlorophyll. It is also responsible for root development, water regulation, and disease resistance in plants. Increasing potassium content helps stimulate healthy plant growth.

How is sodium ferrocyanide differentiated from potassium ferrocyanide?

They are different because one is a monopotassic salt while the other is a tetrapotassic salt. While dispositioning, sodium ferrocyanide is produced by simply sodium-ion exchanging potassium ferrocyanide with a sodium salt like sodium carbonate or sodium hydroxide. Potassium ferrocyanide, with the help of ammonium hydroxide, will wash through cation exchange resin before being subjected to heavier cation exchange resins. This results in two distinct products: potassium ferrocyanide and sodium ferrocyanide.