Molecular Formula | H2KO4P |
Molar Mass | 136.085541 |
Density | 2.338 g/mL at 25 °C (lit.) |
Melting Point | 252.6 °C (lit.) |
Boling Point | > 450 °C |
Water Solubility | 222 g/L (20 ºC) |
Solubility | H2O: 1.5M at20°C, clear, colorless |
Vapor Presure | 0Pa at 25℃ |
Appearance | White crystal |
Specific Gravity | 2.338 |
Color | White transparent |
Odor | Odorless |
Maximum wavelength(λmax) | ['λ: 260 nm Amax: 0.046', , 'λ: 280 nm Amax: 0.040'] |
Merck | 14,7659 |
pKa | (1) 2.15, (2) 6.82, (3) 12.38 (at 25℃) |
PH | 4.2-4.6 (20g/l, H2O, 20℃) |
Storage Condition | Store at +5°C to +30°C. |
Stability | Hygroscopic |
Sensitive | Hygroscopic |
MDL | MFCD00011401 |
Physical and Chemical Properties | Properties colorless tetragonal crystals or white crystalline powder. melting point 252.6 ℃ relative density 2.338 solubility in water (90 ℃ for 83.5g/water). Insoluble in alcohol. |
Use | Used as fertilizer, flavoring agent, brewing yeast culture agent, for the preparation of buffer solution, also used in medicine and the manufacture of potassium metaphosphate. |
Safety Description | S24/25 - Avoid contact with skin and eyes. |
UN IDs | N/A |
Toxicity | LD50 skin in rabbit: > 4640mg/kg |
Reference Show more | 1. Zhang Zhengmin, Yang Yilin, Li Meilin, et al. Effects of 2 4-epibrassinolide treatment on soft rot and energy metabolism of peach fruit [J]. Food science 2019 v.40;No.594(05):215-221. 2. Li Chunlong, Li Xiaoshuang, Xu Xia. Simulation and visual measurement of system pH during freeze-drying [J]. Journal of Shandong University (Natural Science Edition) 2013(05):39-42. 3. Li Tianye, Liu Weihua [1,2], Liang Na, et al. Evaluation of gingerols and their antioxidant activities in ginger and its processed products [J]. Food Industry, 2016(12):180-183. 4. Qian Weidong, Fu Yunfang, Hu Na. Study on fermentation conditions of lactase production by Klyveromyces lactis yeast [J]. Chinese agricultural bulletin, 2012. 5. Jiang Yu, Zhang Miao, Tang Jing, Jin Peng, Zheng Yong Hua. Effects of cold shock combined with salicylic acid treatment on chilling injury and energy and proline metabolism of cucumber fruit [J]. Journal of Nuclear Agriculture, 2021,35(01):128-137. 6. Zheng Liting, Zhou Hong, Liu Yiming, Lin Aihua. Inhibitory effect of phellodendrine on α-glucosidase in vitro [J]. Journal of Nanjing University of Traditional Chinese Medicine, 2020,36(06):853-858. 7. [IF = 4.155] Siqi Zhang et al."Step-wise immobilization of multi-enzymes by zirconium-based coordination polymer in situ self-assembly and specific absorption."J Inorg Biochem. 2020 Jul;208:111093 8. [IF=1.718] HUA Li Yue et al."Determination of SOD in black ginger extract and its effect on the liver of rats with type 2 diabetes."Food Sci Tech-Brazil. 2022 Mar;42: |
colorless columnar crystal or white crystalline powder. Melting point 96 C; d 2.34. Stable in air. Soluble in about 4.5 water, the aqueous solution is acidic, pH 4. 4~4.7. Insoluble in ethanol. At 400 deg C water loss to form potassium metaphosphate.
phosphoric acid was added to water, and potassium hydroxide or potassium carbonate was added thereto. The filtrate was concentrated to a relative density of 1.32 by heating and filtration. Cooling, suction and filtration out of the crystal, that is, potassium dihydrogen phosphate.
This product shall be calculated as dry product, and the content of KH2PO4 shall not be less than 99.0%.
analysis reagent, pH buffer. For the preparation of buffer, determination of arsenic, antimony, phosphorus, aluminum and iron I preparation of phosphorus standard solution and haploid breeding medium, determination of serum inorganic phosphorus, alkaline acid enzyme activity, preparation of bacterial serum test Leptospira medium and the like. It is also used for the generation of harmonics of piezoelectric elements, electro-optical elements and laser light.
The product of the aqueous solution of potassium salt and phosphate identification reaction (General 0301).
take l.Og of this product, add water to dissolve 20ml, and then determine it according to law (General rule 0631). The pH value should be 4.2~4.5.
take this product l. Add 10ml of water to dissolve, and check according to law (General rule 0901 and general rule 0902), the solution should be clear and colorless; If it is turbid, it should not be more concentrated than the No. 1 turbidity standard solution (General rule 0902).
Take 5.0g of this product and check it according to law (General rule 0801). Compared with the control solution made of 0.001% of standard sodium chloride solution, it should not be more concentrated ().
take 3.3g of this product and check it according to law (General rule 0802). Compared with the control solution made of 0.003% of standard potassium sulfate solution, it should not be more concentrated ().
take 2.0g of this product, add 10ml of water, boil, cool, add 2ml of hydrochloric acid, no bubbles should be generated.
take 2.0g of this product, put it in a 100ml measuring flask, add water to dissolve and dilute to the scale, shake well. Add 1.0 of dilute acetic acid and 5.0 of acetic acid-sodium acetate solution (17ml of 1 mol/L sodium hydroxide solution and 40ml of dilute acetic acid, diluted to ml with water), add water to make 15ml, add 2ml of gas barium test solution, shake, at 25 ° c ± 2 ° c, 15 minutes, no turbidity.
take 10.0g of this product, heat 100ml of water to dissolve, filter with No. 4 vertical melting glass crucible with constant weight in advance, and wash the precipitate with 200ml of hot water for 10 times, after drying at 105 ° C. For 2 hours, the residue should not exceed 20mg(0.2%).
Take 5.0g of this product, add fresh boiling and cooling water to dissolve and dilute to 50.0, take 5.0, add dilute sulfuric acid 5M l and potassium permanganate titration solution (0.02mol/L)0.25, in the water bath heating for 5 minutes, the solution of purple red color should not disappear.
take this product, at 105 ° c, dry to constant weight, weight loss should not exceed 0.2% (General 0831).
take this product l. Add 10% sulfosalicylic acid solution (2ml), shake well, add ammonia test solution (5ml), shake well, if color develops, use standard iron solution (0807). 0.001% compared with the control solution prepared by the same method, it should not be deeper ().
take this product 2.0g, inspection according to law (General Principles 0821 The first law), containing heavy metals shall not exceed 10 parts per million.
take 1.0g of this product, add 23ml of water to dissolve, add 5ml of hydrochloric acid, check according to law (General rule 0822 first law), should comply with the provisions (0.0002%).
take this product about l.Og, precision weighing, add water 120ml, add thymol phthalein indicator solution 0.5ml, with sodium hydroxide titration solution (lmol/L) titration. Each 1 ml of sodium hydroxide titration solution (1 mol/L) corresponds to 49.00 mg of H3PO4.
pharmaceutical excipients, pH regulator.
sealed storage.
results from the interaction of phosphoric acid with potassium carbonate in an appropriate ratio.
slowly add the calculated amount of potassium hydroxide solution in phosphoric acid neutralization reaction to generate potassium dihydrogen phosphate solution, and then after decolorization, filtration, concentration, cooling, precipitation crystallization, and then centrifugal separation, drying to give the finished product.
first-class product
Potassium dihydrogen phosphate (KH2PO4 on dry basis) content,% ≥ 98.0 97.0 96.0 92.0
Moisture content,% ≤ 2.5 3.0 4.0 5.0
PH 4.3-4.7 4.3-4.7
Water-insoluble matter content,% ≤ 0.20 0.50 -
Chloride (Cl) content,% ≤ 0.20 -
Iron (Fe) content% ≤ 0.003
Arsenic (As) content,% ≤ 0.005
Heavy metal (Pb) content,% ≤ 0.005
Potassium chloride (K2O on dry basis) content,% ≥ 33.9 33.5 33.2 31.8
project indicators
Food Grade
Potassium dihydrogen phosphate (KH2PO4 on dry basis) content,% ≥ 98.0
Loss on drying content% ≤ 1.0
Water-insoluble matter content,% ≤ 0.2
Arsenic (As) content,% ≤ 0.0003
Heavy metal (Pb) content,% ≤ 0.002
Fluoride (in F) content,% ≤ 0.001
Lead (in terms of Pb) content,% ≤ 0.0005
There are many production methods of potassium dihydrogen phosphate, which can be summarized as neutralization method, extraction method, ion exchange method, double decomposition method, direct method, crystallization method and electrolysis method. In our country, the production process of neutralization method, followed by organic extraction, double decomposition method, ion exchange method.
A 30% solution of caustic potash or potassium carbonate is sent to a neutralizer and neutralized with 50% phosphoric acid solution under stirring at a temperature of 80-100 °c and a pH of 4-5, the neutralized product is obtained by filtration, concentration, cooling crystallization, centrifugal separation and drying, and the crystallization mother liquor is returned to the concentration section for reuse. The process flow of producing potassium dihydrogen phosphate by neutralization method is shown in Fig. 1 (Omitted), and its chemical reaction formula is:
H3PO4 +KOH = KH2PO4 + H2O
2H3PO4 +K2CO3=2KH2PO4 + H2O + CO2↑
Features: short process flow, mature technology, less equipment, high product quality, low energy consumption, less investment. The method uses thermal phosphoric acid and potash as raw materials, which has high production cost and is difficult to apply in agriculture. It is mainly used for the production of food, medicine and industrial grade potassium dihydrogen phosphate, but there is no other way to shake the dominance of its products in the food industry. At present, the national production capacity of neutralized potassium dihydrogen phosphate accounts for more than 90% of the total production capacity.
organic extraction method and inorganic extraction method, the current industrial method for the organic extraction method.
The organic extraction method is a method for preparing potassium dihydrogen phosphate by selectively using an organic solvent for extraction and separation according to the characteristic that the organic solvent has different solubilities for different compounds. It is in the presence of a suitable organic solvent (S), through the reaction of potassium chloride and phosphoric acid, the generated hydrochloric acid is almost extracted into the organic solvent, potassium dihydrogen phosphate is crystallized from the aqueous phase, washed and dried to obtain the product potassium dihydrogen phosphate, and the mother liquor is recycled after separation; Hydrochloric acid is back-extracted from the organic phase by the stripping agent, and the extracting agent is recycled in the process.
K + is adsorbed from the solution by potassium chloride solution through styrene cation exchange resin, and then the ammonium dihydrogen phosphate solution is replaced by the resin to prepare potassium dihydrogen phosphate solution, which is then concentrated, after cooling crystallization, centrifugal separation and drying, the finished potassium dihydrogen phosphate is obtained, and the crystallization mother liquor is returned to the concentration section for reuse.
GB 2760-2002(g/kg): wheat flour 5.0; Beverage 2.0.
As potassium source (mg/100g):
FAO/WHO(1984,g/kg):
production method | phosphoric acid double decomposition method The hydrogen chloride gas produced by the metathesis reaction with saturated potassium chloride solution and excess 120 phosphoric acid at 130 ~ 75% ℃ is absorbed with water to produce by-product hydrochloric acid; Then the excess phosphoric acid is neutralized with potassium hydroxide, control end point for the pH value of 4.2~4.6; Finally, cooling and washing, centrifugal separation, drying products, mother liquor can be reused. Neutralization method With constant stirring, the caustic potash is mixed into a solution with a relative density of 1.3 (about 30%) and neutralized with 50% phosphoric acid; The reaction temperature is maintained at 85~100 ° C, the terminal pH value is controlled at 4.2~4.6 (Congo red test paper is light purple); The neutralized liquid is concentrated to the relative density of 1.32~1.33 and filtered, then cooled to 36 ° C: The following crystals, centrifugal separation, the product is dried and the mother liquor can be reused. Potassium carbonate can also be used for neutralization, and the process is similar to the above. KOH+H3PO4→KH2PO4+H2O |
production method | industrial production methods include neutralization method, double decomposition method, extraction method, electrodialysis method, ion exchange method, etc. Double decomposition method of 30% sodium hydroxide solution with distilled water in the reactor, under stirring slowly add 85% Phosphoric acid neutralization reaction, the solution is neutralized to pH 4.1~4.3, prepared sodium dihydrogen phosphate, then add 90% potassium chloride at about 100 ° C for double decomposition reaction, and keep the heat for half an hour to reach equilibrium, add arsenic removal agent and heavy metal removal agent for solution purification, filtration, remove arsenic and heavy metals and other impurities, the filtrate is cooled to normal temperature, add phosphoric acid with arsenic removal to adjust Ph 4.4~4.7, adjust the relative density to 31~32 ° Bé with water, stir for 30 min, the crystals were precipitated and separated by centrifugation to prepare a finished product of potassium dihydrogen phosphate for feed. Its NaH2PO4+KCl→KH2PO4+NaCl When the mother liquor was evaporated to 108-109 ° C., the liquid was turned from clear to white, and sodium chloride crystals were obtained, which were removed by filtration. The filtrate was returned to the procedure for use. |
production method | caustic potash method an iron-removing caustic potash solution (about 30% KOH) was added to an enamel reactor with a stirring and steam jacket, and an appropriate amount of phosphoric acid (diluted to 50% H3PO4) was added slowly with stirring. The neutralization reaction is carried out, the reaction temperature is maintained at 85~100 ℃, the pH value is controlled at 4.2~4.6, and the relative density of the solution at the end of the reaction is 1.32~1.33. After evaporation and concentration to the relative density of 1.38~1.42, sent to the crystallization process, cooled to 36 deg C below the precipitation of crystals, and then separated dehydration, washing, drying, prepared potassium dihydrogen phosphate. Its KOH+H3PO4→KH2PO4+H2O Potassium chloride method 95% potassium chloride is dissolved in 70~80 ° C hot water, adjusted to a solution close to saturation, and 75% phosphoric acid is added to the reactor according to the ratio of KCl:H3PO4 = 1:1.2, the neutralization reaction was carried out at 150 to 170 ° C. To produce potassium dihydrogen phosphate and hydrogen chloride. The hydrogen chloride was recovered as hydrochloric acid by cooling. Dilute potassium hydroxide solution was added to the reaction solution for neutralization, and the end point was controlled at about pH 4.6 ~. After evaporation and concentration, cooling crystallization, centrifugal separation, proper water washing and drying, the potassium dihydrogen phosphate product was obtained. Its H3P04+KCl→KH2PO4+HCl↑ The mother liquor contains a large amount of potassium dihydrogen phosphate, potassium chloride and free acid, and is returned to the process ingredients for use. |
production method | The neutralization method is industrially used, and is produced by the neutralization method of caustic potash phosphoric acid and the neutralization method of potassium chloride phosphoric acid. Caustic potash method see potassium dihydrogen phosphate, increase in arsenic removal agent and removal of heavy metals in solution purification, filtration, removal of arsenic and heavy metals and other impurities in the process. |
Decomposition | 253 °C |
EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
physical properties | potassium dihydrogen phosphate (chemical formula KH2PO4) is a high concentration of phosphorus, potassium compound fertilizer, P2O5 content of 52%, the K20 content was 34%. Small hygroscopicity, good physical properties, soluble in water, at 20 ° C per 100 ml of water can dissolve 23G, aqueous solution is acidic. |
compound fertilizer of phosphorus and potassium | potassium dihydrogen phosphate is a kind of efficient fast-soluble compound fertilizer of phosphorus and potassium, used to provide plant growth and development needs of nutrients, suitable for any soil and crops, especially suitable for phosphorus and potassium nutrient deficiency at the same time areas and phosphorus-rich potassium crops, mostly used for root topdressing, soaking, seed dressing, the effect of increasing yield is significant, if it is used as root fertilization, it can be used as basal fertilizer, seed fertilizer or middle-late topdressing. aqueous solution can react with silver nitrate to form yellow silver dihydrogen phosphate precipitate, which can be used as an identification reaction. because potassium dihydrogen phosphate is more expensive and the production of agricultural products is less, it is often used in the method of soaking or root dressing. The concentration of field crops soaking commonly used 0.2%, soaking 18~20h, dry after sowing. If a separate spray when used as root topdressing, the highest concentration can be used 0.5%. Such as wheat, rice jointing booting stage, cotton, rape flower flowering period can be sprayed 1~2 times. Spray 2 times, the interval of about 7~10 days, the amount of liquid per mu of about 100 ~ 150kg. Can also be combined with other nutrients into a compound nutrient solution for root topdressing. Such as China's North China for a variety of field crops of leaf fertilizer, its main components are potassium dihydrogen phosphate, urea and with some trace elements. In recent years, the page compound nutrient solution used in various parts of China also mostly uses potassium dihydrogen phosphate as a source of high concentration and good hydrophilicity of phosphorus and potassium fertilizer. With the development of greenhouse crops, drip irrigation and fertilizer irrigation, the demand for potassium dihydrogen phosphate products is increasing day by day. |
The role of potassium dihydrogen phosphate | 1, promote the absorption of nitrogen and phosphorus. Potassium dihydrogen phosphate can promote the absorption of nitrogen and phosphorus in crops, quickly supplement phosphorus, improve crop yield and grain weight, and play a special role in the special physiological period of crops. 2. Promote photosynthesis. Potassium plays a role in enhancing crop photosynthesis and accelerating nutrient production and transformation in crop growth. 3. Improve the ability of crop resistance. Potassium dihydrogen phosphate can improve the stress resistance of crops, such as drought resistance, dry hot wind resistance, waterlogging resistance, frost resistance, damage resistance, healing, resistance to pathogen infection and so on. 4. Improve fruit quality. Fruit expansion spraying can play a strong fruit, promote fruit expansion, can improve fruit quality, increase coloring, improve taste and so on. 5. Regulate balanced growth of crops. Potassium dihydrogen phosphate has the effect of regulator, can promote the differentiation of crop flower bud, increase the number of flowering, flower bud, strong flower and fruit, improve fruit set, but also can effectively promote the growth and development of root system. |
method of use | high purity potassium dihydrogen phosphate nutrients 52% phosphorus and 34% potassium. The effect of phosphorus on the growth of root, stem and peel of crops is significant, and it also has obvious effect on enhancing the disease resistance, cold resistance and waterlogging resistance of crops. And potassium has a significant effect in improving crop yield, increasing fruit quality and improving sugar content. There are several key periods of potassium dihydrogen phosphate in use The first is the flower bud differentiation stage The flower bud differentiation stage of phosphorus demand is relatively large, and phosphorus element to improve crop flowering fruit set rate, there is also a very good effect in reducing the fall of flowers and fruits. Therefore, spraying 500 times of potassium dihydrogen phosphate on the leaf surface during flower bud differentiation will have a multiplier effect. The second is the fruit expansion period we all know that the fruit expansion period is the time when the demand for potassium is the largest. Potassium is irreplaceable for the formation of seeds and the expansion of fruits. Crops are also most sensitive to potassium at this time. In this period, the effect of root application or foliar spraying is the most obvious. Foliar spraying 500 times of potassium dihydrogen phosphate solution can be mixed with 200 times of glucose and 1000 times of urea solution, which can achieve a multiplier effect. The third is the coloring period fruit coloring is the process of anthocyanin formation, and the formation of anthocyanin is directly related to sugar content and sunlight, the formation of carbohydrates is greatly influenced by potassium. Thus the role of potassium in the process of fruit coloring plays a very important role. Therefore, the effect of foliar application of potassium dihydrogen phosphate 300-500 times liquid in the early stage of fruit coloring is more effective. |
precautions and contraindications | 1. It is forbidden to mix with alkaline products: the pH of the aqueous solution of 1% potassium dihydrogen phosphate is about 4.6, it is acidic, and chemical reactions occur when mixed with alkaline fertilizers and pesticides, and there will be abnormal chemical reactions such as flocculation, precipitation, discoloration, Fever, generation of bubbles, etc, this time will lead to the failure of the function of potassium dihydrogen phosphate. 2. It is forbidden to mix with products containing carbonate (CO3-): carbon dioxide (CO2) gas is generated because the hydrogen ion of carbonate and potassium dihydrogen phosphate reacts. Such as potassium carbonate, ammonium carbonate, ammonium bicarbonate, sodium bicarbonate and so on. 3. It is prohibited to mix with products containing copper ions: Potassium dihydrogen phosphate cannot be mixed with copper preparations such as copper hydroxide, basic copper sulfate, copper calcium sulfate, cuprous oxide, copper complex ammonia, and copper quinolinate, these free copper ions will react with phosphate ions to form flocculation and precipitation. 4. Excessive use in the early stage of growth is prohibited: potassium can produce antagonism with magnesium and calcium plasma, which affects the absorption of these two kinds of ions and is not conducive to the growth of plant cells, affect the plant seedling length, for the later yield greater impact. Therefore, in vegetables and beans seedling stage (1-3 leaves) and flowering period before, it is not recommended to use potassium dihydrogen phosphate, in order to avoid injury seedlings, flowers and pods, if the soybean on the premature use will cause yield reduction. 5. It is forbidden to replace potassium dihydrogen phosphate with base fertilizer: because potassium dihydrogen phosphate has very good water solubility, it is easy to dissolve in water, Buried in the soil, it is also easy to be washed away by the rain, the effect is short, so it is not recommended to use as a base fertilizer, base fertilizer or the use of compound fertilizer, slow-release long-term. Potassium dihydrogen phosphate has good water solubility and quick effect, and can be used for leaf spraying at the critical stage of flower bud differentiation and root flushing. 6, prohibit the use of high temperature time, high concentration: high temperature, will lead to the increase of the concentration of potassium dihydrogen phosphate solution, easy to cause fertilizer damage. If the concentration is too high, it will also cause fertilizer damage to burned leaves and roots. The spraying time of potassium dihydrogen phosphate should avoid the high temperature period at noon, and it is better to use it before 10 am or after 4 pm. High-concentration leaf spraying is prohibited in high-temperature seasons. |
solubility in water (g/100ml) | grams dissolved per 100ml of water at different temperatures (℃): 14.8g/0 ℃;18.3g/10 ℃;22.6g/20 ℃;28g/30 ℃;35.5g/40 ℃; 50.2g/60 ℃;70.4g/80 ℃;83.5g/90 ℃ |
identification test | is the same as "dipotassium hydrogen phosphate (05219). |
content analysis | accurately weigh about 5g of sample pre-dried at 105 ℃ for 4H, put it into a 250ml beaker, water (5.0ml) and 1 mol/L hydrochloric acid (ml) were added and stirred until completely dissolved. The following procedure was carried out according to the method in "dipotassium hydrogen phosphate (05219). 1 mol/L of sodium hydroxide corresponds to 136.1mg of potassium dihydrogen phosphate per ml of B- A volume. |
toxicity | Adl 0-70 mg/kg (calculated as phosphorus), generally recognized as safe. Adl 0~70 mg/kg (in phosphorus, FA 0 cases of HO,1985). Generally Recognized As Safe (U. S. Food and Drug Administration, 1975). According to FAO/WHO(1984): lunch meat, cooked pig front leg meat, cooked ham, cooked meat powder 3 g/kg; Low power concentrated milk, sweet condensed milk, cream 2g/kg; Milk powder, cream Powder 5 g/kg; Processed cheese 9 g/kg; Frozen haddock, perch ferret, salidaceae fish, non-hake fish fillets 5 g/kg; Ready-to-eat broth, 1000 mg/kg; Cold drink 2 g/kg. Adl 0-70mg/kg (total amount of phosphate, calculated as phosphorus; FAO/WHO,2001). ADI is not restrictive (EEC,1990). |
usage limit | GB 2760-2002(g/kg): wheat flour 5.0; Beverage 2.0. As a source of potassium (mg/100g): infant formula powder is less than or equal to 1000; Larger infant formula food 400~1500; Infant supplemental Cereal Powder 200~1000 (all potassium). FAO/WHO(1984,g/kg): lunch meat, cooked pig fore leg meat, cooked ham, cooked meat powder 3 (based on Anhydrous); Low power concentrated milk, sweetened condensed milk, diluted cream, single use 2, combined with other stabilizers 3 (based on Anhydrous); Milk powder, cream powder 5 (based on Anhydrous); Processed cheese 9 (based on phosphorus); Frozen haddock, lateolabrax japonicus consists of 5 pieces of fish (calculated by P2O5), fish of the stoniae family, and hake; Ready-to-eat broth, 1000mg/kg (calculated by P2O5); Cold drink 2 (calculated by P2O5). |
Use | as a quality improver, it can improve the complexation of metal ions, pH value, increase the ionic strength of food, thereby, the binding force and water holding capacity of the food product are improved. China's provisions can be used for wheat flour, the maximum use of 5.0g/kg; The maximum use of 2.0g/kg in the beverage. used as fertilizer, flavoring agent, brewing yeast culture agent, for the preparation of buffer solution, also used in medicine and the manufacture of potassium metaphosphate. for rice, wheat, cotton, rape, tobacco, sugar cane, Apple and other crops fertilization used as chromatographic analysis reagent and buffer, it is also used in the synthesis of medicine as a high-efficiency phosphorus-potassium compound fertilizer, suitable for various soils and crops. It is also used as a bacterial culture agent, a flavoring agent for the synthesis of sake, and a raw material for the preparation of potassium metaphosphate. Used in medicine to make uric acid, as a nutritional agent. used in the food industry for the manufacture of baked goods, as leavening agents, flavoring agents, fermentation aids, nutrition enhancers, yeast food. Also used as a buffer, chelating agent. preparation of buffer solution, determination of arsenic, antimony, phosphorus, aluminum and iron, preparation of phosphorus standard solution, preparation of haploid breeding medium, determination of serum inorganic phosphorus, alkaline acid enzyme activity, preparation of bacterial serum test Leptospira medium and the like. |
production method | caustic potash method to remove iron from caustic potash solution (about 30% KOH) add to the enamel reaction kettle with stirring and steam jacket, slowly add appropriate amount of phosphoric acid (diluted to 50% H3PO4) under stirring for neutralization reaction, and maintain the reaction temperature at 85~100 ℃, the pH value was controlled to 4.2~4.6, and the relative density of the reaction end solution was 1.32~1.33. After evaporation and concentration to the relative density of 1.38~1.42, sent to the crystallization process, cooled to 36 deg C below the precipitation of crystals, and then separated dehydration, washing, drying, prepared potassium dihydrogen phosphate. Its KOH + H3PO4 → KH2PO4 + H2O potassium chloride method to dissolve 95% potassium chloride in 70~80 ° C hot water, adjusted to a solution close to saturation, and 75% phosphoric acid according to KCl:H3PO4 = 1: A ratio of 1.2 was added to the reactor, and neutralization reaction was carried out at 150-170 ° C. To generate potassium dihydrogen phosphate and hydrogen chloride. The hydrogen chloride was recovered as hydrochloric acid by cooling. Dilute potassium hydroxide solution was added to the reaction solution for neutralization, and the end point was controlled at about pH 4.6, After evaporation concentration, cooling crystallization, centrifugal separation, appropriate water washing, and then dried to obtain potassium dihydrogen phosphate finished product. The mother liquor of h3po4 + KCl → KH2PO4 + HCl contains a large amount of potassium dihydrogen phosphate, potassium chloride and free acid, and is returned to the process for use. phosphoric acid double decomposition method at 120~130 ℃, hydrogen chloride gas produced by the double decomposition reaction of saturated potassium chloride solution with an excess of 75% phosphoric acid is absorbed with water to produce by-product hydrochloric acid; then the excess phosphoric acid is neutralized with potassium hydroxide, and the end point is controlled to be pH 4.2~4.6; Finally, the product is cooled, washed, centrifuged and dried, and the mother liquor can be reused. Neutralization method under constant stirring, the caustic potash is mixed into a solution with a relative density of 1.3 (about 30%) and neutralized with 50% phosphoric acid; The reaction temperature is maintained at 85~100 ℃, the terminal pH value is controlled at 4.2~4.6 (Congo red test paper is light purple); The neutralized liquid is concentrated to the relative density of 1.32~1.33 and filtered, then cooled to 36 ° C: The following crystals, centrifugal separation, the product is dried and the mother liquor can be reused. Potassium carbonate can also be used for neutralization, and the process is similar to the above. KOH + H3PO4 → KH2PO4 + H2O (1) neutralization method. Obtained by metered neutralization of phosphoric acid and potassium hydroxide: mix caustic potash with a relative density of 1.3 (about 30%) The solution, under constant stirring, was neutralized with 50% phosphoric acid. The reaction temperature was maintained at 85-100 ° C., and the terminal PH was controlled at 4.2-4.6 * Congo red test paper was light purple). The neutralization solution is concentrated to a relative density of 1.32-1.33, filtered, and then cooled to below 36 °c for crystallization. The product was separated by centrifugation and dried. The mother liquor was recovered. Potassium phosphate can also be used for neutralization, and the process is similar to the above. (2) phosphoric acid double decomposition method. The metathesis reaction was carried out with a saturated potassium chloride solution and an excess of 75% phosphoric acid at 120-130 °c. The hydrogen chloride gas and water produced absorb the by-product acid. The excess phosphoric acid was then neutralized with potassium hydroxide, controlled at the end point PH of 4.2-4.6 and finally cooled to crystallize, centrifuged and dried to give the product. The mother liquor was reused. It is also possible to produce feed potassium dihydrogen phosphate by using thermal phosphoric acid (85) and agricultural potassium chloride as raw materials through the steps of decomposition, neutralization and defluorination. 49g of agricultural KCL was taken, dissolved in 100ml of water, added with 1g of KOH (industrial product), completely dissolved, poured into a flask, and concentrated to a mass of 124-117.5G. 56.4g of phosphoric acid was added while hot, and about 39g of ammonium bicarbonate was added under stirring to adjust PH = 3.0-3.5. The precipitated crystals were filtered, rinsed with 10ml of water and drained. The resulting potassium dihydrogen phosphate was dissolved in 100ml (2%) of KOH solution, into which 2g of SiO2 and a few drops of precipitation aid polyacrylamide were added and stirred for 20min to form a precipitate of potassium fluosilicate, which was cooled to 30 °c, after filtration, an appropriate amount of calcium carbonate as a fluoride removal aid was added and stirred for 10min to form a calcium fluoride precipitate. The filtrate was concentrated and cooled to 35-40 °c, Then, PH4.4-4.7 was returned with phosphoric acid, filtered and dried. industrial production methods include neutralization method, double decomposition method, extraction method, electrodialysis method, ion exchange method, etc. Double decomposition method of 30% sodium hydroxide solution with distilled water in the reactor, under stirring slowly add 85% Phosphoric acid neutralization reaction, the solution is neutralized to pH 4.1~4.3, prepared sodium dihydrogen phosphate, then add 90% potassium chloride at about 100 ° C for double decomposition reaction, and keep the heat for half an hour to reach equilibrium, add arsenic removal agent and heavy metal removal agent for solution purification, filtration, remove arsenic and heavy metals and other impurities, the filtrate is cooled to normal temperature, add phosphoric acid with arsenic removal to adjust Ph 4.4~4.7, adjust the relative density to 31~32 ° Bé with water, stir for 30 min, the crystals were precipitated and separated by centrifugation to prepare a finished product of potassium dihydrogen phosphate for feed. When the NaH2PO4 + KCl → KH2PO4 + NaCl mother liquor was evaporated to 108-109 ° C., the liquid was turned from clear to white, and sodium chloride crystals were obtained, which were removed by filtration. The filtrate was returned to the procedure for use. |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |