Ammonium Persulfate


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 

Chemical formula of ammonium persulfate


Molecular mass of ammonium persulfate

228.18 g/mol

Appearance of ammonium persulfate

Whitish to yellowish crystals

Ammonium persulfate density

1.98g/ \[cm^{3}\]

Melting point of ammonium persulfate

120 °C or 248 °F or 393 K

Ammonium persulfate solubility in water

80 g/100 mL at 25 °C

Ammonium persulfate solubility in others

Partially soluble in MeOH

Ammonium Persulfate Uses

Let us now learn about the ammonium persulfate uses.

Ammonium persulfate is used across several industries in the following ways:

  1. It is used in the printed circuit boards.

  2. It is used in the olefin polymerization as an initiator.

  3. It is used for photography.

  4. It is used as an additive for preserving the food.

  5. It is used as an oxidising agent.

  6. It is used to wash the infected yeast.

  7. It is used for removing the pyrogallol stains.

  8. It is used as a depolarizer in batteries.

  9. 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.

FAQ (Frequently Asked Questions)

1. What is (NH4)2S208?

(NH4)2S208 is called ammonium persulfate. Ammonium persulfate is the chemical name of  (NH4)2S208  . It is also known by other names such as ammonium peroxydisulfate, diammonium persulfate, and diammonium peroxydisulfate. It is an organic compound which is white (colourless) salt. It is highly soluble in water and is a strong oxidising agent which has its uses in organic chemistry, polymer chemistry, as a bleaching and cleaning agent, and as an etchant.

2. How is ammonium persulfate prepared?

Ammonium persulfate is prepared by the process of electrolysis of a cold concentrated solution of either the ammonium bisulfate or the ammonium sulfate in the presence of sulfuric acid at a greater current density. This is the method that was initially described by Hugh Marshall. 

To prepare a 10% (w/v) solution, you need to dissolve 1 g of ammonium persulfate in 10 ml of H2O and store it at 4°C. Ammonium persulfate decays slowly in the solution, so make sure to replace the stock solution every 2-3 week. Ammonium persulfate is used as a catalyst for the process of copolymerization of acrylamide and bisacrylamide gels. The polymerization reaction is driven by the free radicals that are generated by an oxido-reduction reaction in which a diamine is used as the adjunct catalyst.