How Ammonium Persulfate is Used in Chemistry and Industry
(NH4)2S208
Ammonium persulfate or APS is the inorganic compound that has the formula (NH4)2S208 . It is a colourless salt which is highly soluble in water, much more than the related potassium salt. It is a strong oxidizing agent which is used in polymer chemistry, as a cleaning and bleaching agent, and as an etchant. It is also called as ammonium peroxydisulfate, diammonium persulfate, or diammonium peroxydisulfate. It is prepared by using the method of electrolysis of a cold concentrated solution of either of these substances: ammonium sulfate or the ammonium bisulfate, in the presence of the sulfuric acid at a very high current density. In this article, we will learn about what is ammonium persulfate, persulfate uses, its structure and properties in detail.
What is Ammonium Persulfate?
Ammonium persulfate or (NH4)2S208 is a type of an inorganic compound. It is an odourless and crystalline solid that is white in colour. It is readily soluble in water and is a strong oxidizing agent. It has a variety of applications in polymer chemistry, such as a bleaching agent, cleaning agent, and an etchant.
Ammonium Persulfate Structure
The ammonium persulfate structure is shown as below:
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Let us now learn about some of the properties of ammonium persulfate that are given below:
Properties of Ammonium Persulfate
Ammonium Persulfate Uses
Let us now learn about the ammonium persulfate uses.
Ammonium persulfate is used across several industries in the following ways:
It is used in the printed circuit boards.
It is used in the olefin polymerization as an initiator.
It is used for photography.
It is used as an additive for preserving the food.
It is used as an oxidising agent.
It is used to wash the infected yeast.
It is used for removing the pyrogallol stains.
It is used as a depolarizer in batteries.
It is used as a common ingredient in the hair bleaches.
Production of Ammonium Persulfate
Let us now take a look at how is ammonium persulfate produced.
Ammonium persulfate can be derived by the method of electrolysis of ammonium sulfate and dilute sulfuric acid which is then crystallized.
The electrolytic process of ammonium sulfate and sulfuric acid formulates to form a liquid electrolyte which is decontaminated by the electrolysis process. \[HS0-_{4}\] can discharge and generate the peroxydisulfate acid in the anode and it then reacts with ammonium sulfate to generate ammonium persulfate. Ammonium persulfate goes through the processes of filtration, crystallization, centrifugal separation, and drying to get the ammonium persulfate product when the content reaches up to a certain concentration in the anode.
Anode reaction: \[2HS0_{4}\] - 2e \[\rightarrow\] \[H_{2}\] \[S_{2}\] \[0_{8}\]
Cathodic reaction: \[2H^{+}\] + 2e \[\rightarrow\] \[H_{2}\] ↑
This gives:
\[NH_{4}\] \[2S_{2}\] \[0_{4}\] + \[H_{2}\] \[S_{2}\] \[0_{8}\] \[\rightarrow\] \[NH_{4}\] \[2S_{2}\] \[0_{8}\] + \[H_{2}\] \[S0_{4}\]
Ammonium Persulfate Side Effects
Ammonium persulfate has its own share of side effects. Let us look at what are these.
The airborne dust that contains ammonium persulfate may be irritating to eye, nose, throat, lung and skin on contact. Exposure to high levels of dust can also cause difficulty in breathing.
It has been noted that the persulfate salts are a major cause of several asthmatic effects amongst women. Also, it has been suggested that the exposure to ammonium persulfate can lead to several asthmatic effects amongst the hairdressers and receptionists that are working in the hairdressing industry. These asthmatic effects are known to be caused by the oxidation of cysteine as well as methionine residues.
FAQs on Ammonium Persulfate: Properties, Structure, and Applications
1. What is Ammonium Persulfate and what is its chemical formula?
Ammonium Persulfate is an inorganic compound with the chemical formula (NH₄)₂S₂O₈. It is the salt of ammonium and persulfate ions. Often appearing as a white or colorless crystalline solid, it is known for being a very strong oxidizing agent and is highly soluble in water.
2. What are the main uses of Ammonium Persulfate in industry and labs?
Ammonium Persulfate has several important applications due to its strong oxidizing properties. Key uses include:
- Polymer Chemistry: It acts as an initiator for the polymerization of certain plastics, like polystyrene and polyacrylonitrile.
- Electronics: It is used for etching printed circuit boards (PCBs) by dissolving copper.
- Cosmetics: It is a common ingredient in hair bleaches and lighteners.
- Disinfectant: It can be used as a cleaning and disinfecting agent.
- Organic Synthesis: It serves as a specialised oxidizing agent in various chemical reactions.
3. How is Ammonium Persulfate typically prepared?
Ammonium Persulfate is prepared commercially through the electrolysis of a cold, concentrated solution of either ammonium sulfate or ammonium bisulfate mixed with sulfuric acid. This process, conducted at a high current density, causes the sulfate ions to combine and form the peroxydisulfate ion.
4. Can you explain the chemical structure of Ammonium Persulfate?
The structure consists of two ammonium cations (NH₄⁺) and one peroxydisulfate anion (S₂O₈²⁻). The most important feature of the anion is the peroxide-like bond (-O-O-) that connects two sulfate groups. This weak O-O bond is the reason for its strong oxidizing nature, as it can easily break to form highly reactive radicals.
5. What makes Ammonium Persulfate such a strong oxidizing agent?
Its strength as an oxidizing agent comes from the peroxydisulfate ion (S₂O₈²⁻). The bond between the two central oxygen atoms is relatively weak and unstable. When this bond breaks, it forms two sulfate free radicals (SO₄⁻•), which are extremely reactive and readily accept electrons from other substances, thereby oxidizing them.
6. In lab experiments like gel electrophoresis, what is the combined function of APS and TEMED?
In gel polymerization, Ammonium Persulfate (APS) and TEMED work as a team. APS acts as the initiator, providing the free radicals needed to start the reaction. However, this process is slow on its own. TEMED acts as a catalyst, rapidly accelerating the rate at which APS forms these free radicals, which then triggers the polymerization of acrylamide to form the gel matrix.
7. Why do ammonium persulfate solutions need to be prepared fresh before use?
Ammonium persulfate is not very stable in water. Over time, it slowly decomposes, breaking down and losing its oxidizing power. For time-sensitive and concentration-dependent reactions like polymerizing a gel, using a freshly prepared solution ensures that its concentration is accurate and its initiating ability is at its peak, leading to consistent and reliable results.
8. What safety precautions are important when handling Ammonium Persulfate?
Yes, because it is a strong oxidizer and can cause irritation, certain precautions are necessary. It is important to:
- Wear protective gear like gloves and safety glasses.
- Work in a well-ventilated area to avoid inhaling its dust.
- Keep it stored away from heat sources and flammable materials.
- Avoid direct contact with skin and eyes.
