He potassium sulfate , Also known as arcanite, is a chemical compound whose formula is K 2 SW 4 . Its structure is shown in figure 1 (EMBL-EBI, 2014).
Potassium sulfate has been known since the beginning of the 14th century and was studied by Glauber , Boyle And Tachenius. In the seventeenth century, it was called arcanuni or salt duplicatum, as it was a combination of an acid salt with an alkaline salt.
Figure 1: structure of potassium sulphate
It was also known as treating vitriolic and Glaseri salt or Glaseri polychrestum salt, after the pharmaceutical chemist Christopher Glaser prepared and used it medicinally.
Potassium is a relatively abundant element in the earth's crust, and the production of potash fertilizer occurs on every inhabited continent. However, the K 2 SW 4 It is seldom found in a pure form in nature. Instead, it is naturally mixed with salts containing magnesium, sodium and chloride.
These minerals require additional processing to separate their components. Historically, K was prepared 2 SW 4 Reacting KCl with sulfuric acid . However, later, researchers discovered that they could manipulate a number of minerals from the earth to produce K 2 SW 4 , The most common production method today.
Natural K-containing minerals (such as kainite and schoenite) are carefully extracted and washed with water and saline solutions to remove by-products and produce K 2 SW 4 . The mining industry uses a similar process to harvest K 2 SW 4 The Great Salt Lake in Utah and underground mineral deposits.
In New Mexico, the K 2 SW 4 Is separated from the langbeinite minerals by reacting it with a KCl solution, which removes by-products (such as Mg) and leaves K 2 SW 4 . Similar processing techniques are used in many parts of the world, depending on the raw materials available (The Mosaic Company, 2016).
The compound is also obtained by the reaction of potassium chloride with sulfuric acid or sulfur dioxide, water and oxygen (Hargreaves process) (U.S. National Library of Medicine, 2002).
Physical and chemical properties of potassium sulphate
Potassium sulfate is a group of white orthorhombic crystals, without a characteristic aroma and with a slightly bitter salty taste (National Center for Biotechnology Information., 2017). Their appearance is shown in figure 2.
Figure 2: appearance of potassium sulfate
Its molecular weight is 174.259 g / mol and its density is 2.662 g / ml. It has a melting point of 1069 ° C and a boiling point of 1689 ° C. The compound is very soluble in water being able to dissolve 120 grams of this compound for each liter of water. It is also slightly soluble in glycerol and insoluble in alcohol And ketones.
Potassium sulfate (also known as potassium bisulfate), KHSO 4 , Is easily produced by reacting K 2 SW 4 With sulfuric acid. It forms rhombic pyramids, which melt at 197 ° C. It dissolves in three parts of water at 0 ° C.
The solution behaves as if its two congeners, K 2 SW 4 And H 2 SW 4 , Were present side by side without combining. An excess of ethanol precipitates normal sulfate (with little bisulfate) with excess acid remaining.
The behavior of the molten dry salt is similar when heated to several hundred degrees. It acts on silicates, titanates, etc., in the same way as sulfuric acid that is heated beyond its natural boiling point.
Therefore, it is frequently used in analytical chemistry as a disintegrating agent. At high temperatures, it is reduced to potassium sulfide by the action of carbon monoxide.
Reactivity and hazards
Potassium sulfate is classified as stable, can cause severe gastrointestinal irritation if swallowed in large doses. The substance is toxic to the lungs and mucous membranes. Repeated or prolonged exposure to the substance may cause damage to these organs.
If the compound comes into contact with the eyes, contact lenses should be checked and removed. Immediately flush eyes with copious amounts of water for at least 15 minutes with cold water.
Skin contact
In case of skin contact, rinse the affected area immediately with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Cover irritated skin with an emollient.
Wash clothing and shoes before reuse. If contact is severe, wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream.
Inhalation
In case of inhalation, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen.
Ingestion
If the compound is ingested, do not induce vomiting unless directed to do so by medical personnel. Loosen tight clothing such as a shirt collar, belt or tie.
In all cases, immediate medical attention should be obtained (Material Safety Data Sheet Potassium sulfate, 2013).
Applications
Potassium sulfate is mainly used in agriculture as fertilizer. It is also essential for the production of alum.
1- Agriculture
Figure 3: 50 kg of commercial potassium sulfate for agriculture.
Potassium is needed to complete many essential functions in plants, such as activation of enzymatic reactions, protein synthesis, formation of starch and sugars, and regulation of water flow in cells and leaves.
Often, concentrations of K in the floor Are too low to support healthy plant growth.
Potassium sulfate is an excellent source of potassium nutrition for plants. The potassium portion of K 2 SW 4 It is no different from other common potash fertilizers.
However, it also provides a valuable source of sulfur, which protein synthesis and enzyme function require. Like potassium, sulfur may also have a deficit for proper plant growth.
Potassium sulfate is only one third as soluble as potassium chloride (KCl), so it is not as commonly dissolved for addition through irrigation water unless there is an additional need for sulfur (Fertilizer Brokerage, 2016 ).
However, one of the benefits of potassium sulfate is that it is not an extremely high pH fertilizer product.
Potassium chloride, on the other hand, is a little higher in pH and has the tendency, when used over time, to raise the pH and can be misleading for people who only look at this component and then do not put calcium or Limestone to control it.
Potassium sulfate, due to sulfate actually, will not increase soil pH. It is more a neutral pH, reason why it is a product quite superior only by the aspect of the pH.
A lot of soil, especially small orchards, do not need it. But many of the larger scale farming operations find a need for potassium sulfate (International Plant Nutrition Institute, S.F.).
The partial salt index of K 2 SW 4 Is lower than in some other common K fertilizers, so that less total salinity per unit of K is added. The salt measure (EC) of a solution of K 2 SW 4 Is less than one third of a similar concentration of a solution of KCl (10 millimoles per liter).
When high K rates are needed 2 SW 4 , Agronomists generally recommend applying the product in multiple doses. This helps prevent excess K accumulation by the plant and also minimizes any potential salt damage.
2- Production of alum
The aluminum sulfate solution and the potassium sulfate solution are mixed together to crystallize and obtain a new salt class called aluminum and potassium sulfate K 2 SW 4 To the 2 (SW 4 ) 3 · 24H 2 O. This complex salt is commonly referred to as alum.
From the point of view of composition, it is formed by the adduct of two simple salts, not a simple mixture of the two salts, but the compound of the same crystalline structure. The difference between the complex salt and the complex is that in the solid state or solution, the complex salt has simple ions, without complex ions.
Alums have many uses, but have been partially supplanted by aluminum sulphate itself, which is readily obtainable by treating the bauxite ore with sulfuric acid. The commercial uses of the alums come mainly from the hydrolysis of the aluminum ions, which results in the precipitation of the aluminum hydroxide.
This chemical has several industrial uses. The paper is sized, for example, by depositing aluminum hydroxide in the interstices of the cellulose fibers. The aluminum hydroxide adsorbs the suspended particles from the water and, therefore, is a useful flocculating agent in water purification plants.
When used as a mordant (binder) in dyeing, the dye is fixed to cotton and other fabrics, making it insoluble. Alums are also used in pickling, baking powder, extinguishers and astringents in medicine (Britannica, 2007).
References
- Britannica, T. E. (12 April 2007). Obtained from britannica: britannica.com.
- EMBL-EBI. (July 28, 2014). Potassium sulfate . Retrieved from ebi.ac.uk: ebi.ac.uk.
- Fertilizer Brokerage. (2016). Potassium Sulfate . Retrieved from fertilizerbrokerage: fertilizerbrokerage.com.
- International Plant Nutrition Institute. (S.F.). Potassium Sulfate. Retrieved from ipni.net: ipni.net.
- Material Safety Data Sheet Potassium sulfate. (May the 21th, 2013). Retrieved from"sciencelab: sciencelab.com.
- National Center for Biotechnology Information. . (March 25, 2017). PubChem Compound Database; CID = 24507 . Retrieved from PubChem: pubchem.ncbi.nlm.nih.gov.
- The Mosaic Company. (2016). Potassium Sulfate . Retrieved from cropnutrition: cropnutrition.com.
- S. National Library of Medicine. (November 8, 2002). POTASSIUM SULFATE . Retrieved from toxnet: toxnet.nlm.nih.gov.