Ammonium persulfate: synthesis and practical importance

Ammonium persulphate is used to intensify polymerization processes, as well as for condensation in the process of production of rubbers, plastics and latex, in photography, etching of printed circuit boards. This substance is sometimes used for disinfection and bleaching.

Ammonium persulfate: physical and chemical properties

Chemreactivity is a colorless lamellar crystal, sometimes having a greenish tinge. Poorly soluble in H2O (42.7%) at a temperature of 15.5 ° C. In the process of heating above 120 degrees, forms pyrosous ammonium, while oxygen is released. It should be noted that dry salt can last almost indefinitely, while the wet salt quickly hydrolyses with the release of oxygen and nitrogen. Aqueous solutions of this compound begin to hydrolyze even at room temperature, with increasing temperature, the decay process increases. In order to slow down the decomposition, alum -alkali alum or alkali metal sulfates are added to the aqueous solutions of ammonium persulphate.

Ammonium persulfate: synthesis

The reagent is obtained by electrolysis of a solution of ammonium sulfate in sulfate acid. To do this, take a jar with a diameter of 20 centimeters and a volume of two liters, pour into it 1.7 liters of saturated solution of ammonium sulfate and five milliliters of sulfate acid. The resulting mixture is then subjected to electrolysis using electrodes made of platinum wire. If in the process of electrolysis begins to smell of ammonium hydroxide, then add three to five ml of a saturated solution of ammonium sulfate in sulfate acid. After every three to four hours, the current is turned off and the electrodes are wiped. After 24 hours of electrolysis, 90 g of mashed ammonium sulfate are added and the electrolysis continues for an additional 70 hours. During the electrolysis, stir the solution regularly. The resulting crystals of ammonium persulfate are separated, and the solution is again saturated with ammonium sulfate and acidified with sulfate acid. The resulting precipitate is dried at a temperature of not more than 40 degrees.

As a rule, the preparation obtained by this method contains no more than 90% of ammonium chloride, it is often used as an oxidizing agent. A reagent with a lower concentration of active substance is recrystallized. For its implementation, 700 g of salt is dissolved in an identical volume of warm water (about 40 ° C). Next, using a paper fold filter, the analyzed solution is filtered off, after which the filtrate is cooled. The obtained crystals of purified ammonium persulfate are sucked off on a Buchner funnel and washed with water. The resulting preparation, as a rule, corresponds to the requirements for the qualification reagents ch.da.

Ammonium persulfate is explosive and fireproof, but promotes the ignition of other substances. In the process of combustion, it releases irritating and toxic substances. Contact of this reagent with combustible substances is unacceptable, since it refers to strong oxidants and reacts with combustible materials, as well as with reducing agents. During heating, ammonium persulfate decomposes rapidly, and many toxic and corrosive gases are released (nitrogen oxides, ammonia vapor, sulfur oxides). By the degree of impact on the human body, it refers to substances of the third hazard class. The maximum permissible dose in the air of the working area for ammonium persulfate is 0.1 mg per cubic meter.

Ammonium persulfate exerts an irritating effect on the skin, as well as on the mucous membranes of the nasal, oral cavity, respiratory tract, conjunctiva. Inhalation of this substance provokes the development of asthmatic disease. With prolonged or repeated contact, there are dermatitis, eczema, which are often accompanied by allergic reactions manifested in the form of nettle fever and shock.

When working with the reagent, it is necessary to use a variety of personal protective equipment (respirator, rubber goggles, overalls).