Introduction

Dipotassium hydrogen phosphate is an inorganic compound with chemical formula K2HPO4. It is white crystal or amorphous white powder in appearance. It is easily soluble in water. The aqueous solution is slightly alkaline and slightly soluble in alcohol. It has hygroscopicity and is self soluble at high temperature. When the relative density is 2.338204 ℃, the internal dehydration of the molecule is transformed into potassium pyrophosphate. The pH value of 1% aqueous solution is 8.9. It is mainly used in medicine, fermentation, bacterial culture and preparation of potassium pyrophosphate[1].

Picture 1 Dipotassium hydrogen phosphate powders

Production method

Industrial production is made by neutralizing phosphoric acid with caustic potassium solution, or by neutralizing phosphoric acid with potassium carbonate solution first and then caustic potassium solution[2].

Neutralization method

Prepare solid caustic potassium into 30% aqueous solution, clear and filter to remove impurities, add it into the corrosion-resistant reaction tank after measurement, slowly add an appropriate amount of 50% phosphoric acid solution under stirring, and carry out neutralization reaction at 90 ~ 100 ℃, and the reaction end point is controlled at pH8 5 ~ 9.0 (use phenolphthalein as indicator until it just turns red). Heat to 120 ~ 124 ℃ for concentration, and filter to remove insoluble matter after the solution concentration reaches the required range. The clarified filtrate is cooled to below 20 ℃, precipitated and crystallized, then centrifuged and slightly air dried to prepare the finished product of potassium hydrogen phosphate. The reaction equation is as follows:

H3PO4+2KOH→K2HPO4+2H2O

The mother liquor is filtered and returned to the process for use.

Potassium carbonate method

Under continuous stirring, add potassium carbonate solution to 30% phosphoric acid solution for reaction, and the neutralization end point is pH 8.5 ~ 9.0 (phenolphthalein indicator just turns red); The neutralization solution is concentrated to 120 ~ 124 ℃, filtered to remove insoluble matter, and then cooled to below 20 ℃ for crystallization; The product is centrifuged and dried, and the mother liquor is sent to the neutralization process for reuse [2]. The reaction equation is as follows:

K2CO3+H3PO4→K2HPO4+H2O+CO2↑

Product application

1. It is mainly used in medicine (culture agent of penicillin and streptomycin) industry. It can also be used as iron remover and pH regulator of talc powder.

2. It is used as water treatment agent, microorganism and fungus culture agent.

3. The food industry is used as raw material for preparing alkaline water for pasta products, fermentation agent, flavoring agent, bulking agent, mild alkaline agent for dairy products and yeast food. Sometimes it is added to milk tea powder. It can also be used as feed additive.

4. It is used as buffer in chemical analysis, phosphating treatment of metals and electroplating additive.

Toxicology data of dipotassium hydrogen phosphate

Acute toxicity: LD50: 4000mg / kg (oral to rats); 4720mg / kg (rabbit percutaneous); LC50: 9400mg / m3, 2h (inhaled by mice).

Editing and broadcasting of first aid measures

First aid

Inhalation: if inhaled, move the patient to fresh air.

Skin contact: take off contaminated clothes and wash skin thoroughly with soapy water and clear water. If you feel unwell, see a doctor.

Eye contact: separate the eyelids and rinse with flowing water or normal saline. Seek medical attention immediately.

Ingestion: gargle and do not induce vomiting. Seek medical attention immediately.

Advice to protect rescuers: Transfer the patient to a safe place. Consult a doctor. Show this chemical safety technical manual to the doctor on site.

Application

Dipotassium hydrogen phosphate can be used as corrosion inhibitor of antifreeze, nutrient of antibiotic culture medium, phosphorus and potassium regulator of fermentation industry, feed additive, medicine, fermentation, bacterial culture and preparation of potassium pyrophosphate, as feed phosphorus supplement additive. Potassium hydrogen phosphate can also be used as water treatment agent, microorganism, fungus culture agent and other purposes. It is often used as analytical reagent and buffer. It is also used in pharmaceutical industry. In food industry, it is used as raw material for preparing alkaline water for pasta products, fermentation agent, flavoring agent, bulking agent, mild alkaline agent for dairy products and yeast food. Dipotassium hydrogen phosphate can be used as buffer, chelating agent and analytical reagent. Buffers and pharmaceuticals. Dipotassium hydrogen phosphate can be used for boiler water treatment. In medicine and fermentation industry, dipotassium hydrogen phosphate can be used as phosphorus and potassium regulator and bacterial culture medium. It is the raw material for producing potassium pyrophosphate. It can be used as liquid fertilizer and corrosion inhibitor of ethylene glycol antifreeze. Feed grade is used as feed nutritional supplement. Potassium dihydrogen phosphate can be used as a product quality improver, which can improve the complex metal ions, pH value and ionic strength of food, so as to improve the bonding force and water holding capacity of food. China stipulates that dipotassium hydrogen phosphate can be used for fat planting powder, with a maximum dosage of 19.9g/kg.

Reference

1 Huo Qing, Wang Qiang Separation and purification of chlorogenic acid by acetone / dipotassium hydrogen phosphate aqueous two-phase system. 2008

2 Liu Kai, Jiang Fan, Zhang Chao, Zhang Binbin, etc Failure mechanism of magnesium phosphate cement modified by potassium hydrogen phosphate under water curing. 2012