A process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water

Abstract

This invention discloses a process for producing pharmaceutical-grade potassium dihydrogen phosphate using corn soaking water. It relates to the field of potassium dihydrogen phosphate production technology. The process involves potassium phytate adsorption and desorption, potassium phytate concentration, potassium phytate hydrolysis, separation, concentration, decolorization and filtration, wet preparation of potassium dihydrogen phosphate, drying, and packaging. The process effectively removes divalent and polyvalent metal ions, chloride ions, and organic impurities, resulting in a high-purity potassium dihydrogen phosphate product that meets pharmaceutical-grade standards.

Description

Technical Field

[0001] This invention relates to the field of potassium dihydrogen phosphate production technology, specifically to a process for producing pharmaceutical-grade potassium dihydrogen phosphate using corn soaking water. Background Technology

[0002] Potassium dihydrogen phosphate (KH2PO4) is an important chemical product widely used in agriculture, industry, food, and medicine. Industrially, it is used as a buffer and culture medium; in agriculture, it is used as a high-efficiency phosphorus-potassium compound fertilizer, offering numerous benefits such as increased yield, improved quality, lodging resistance, pest and disease resistance, and prevention of premature aging; in the food industry, KH2PO4 can be used as a fermentation agent, flavoring agent, leavening agent, and a mild alkaline agent for dairy products; in medicine, a compound potassium dihydrogen phosphate injection, composed of potassium dihydrogen phosphate and potassium hydrogen phosphate, is used as a parenteral nutrition supplement. Phosphorus participates in dephosphorylation in glucose metabolism, forming phospholipids in membrane components, and is an important component of intracellular RNA, DNA, and many coenzymes. Phosphorus also participates in energy storage, conversion, transport, and regulation of body fluid buffering functions.

[0003] Corn soaking water is a byproduct of wet corn starch production, containing 1-2% w / w phytic acid. Currently, there are reported processes for recovering phytic acid from corn soaking water to prepare potassium phytate, followed by hydrolysis, separation, concentration, and crystallization to produce inositol and potassium dihydrogen phosphate. Traditional potassium dihydrogen phosphate production processes, such as neutralization and metathesis methods, use phosphoric acid, potassium hydroxide, or potassium chloride as raw materials. The impurities in these products are mainly inorganic ions, such as calcium, fluorine, and chlorine. However, the impurities in corn soaking water are more complex, containing not only inorganic ions like calcium and magnesium but also organic impurities such as proteins, polysaccharides, and lactic acids. Therefore, potassium dihydrogen phosphate produced from corn soaking water currently has high levels of residual impurities and cannot meet the quality standards of the pharmaceutical industry. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a process for producing pharmaceutical-grade potassium dihydrogen phosphate by soaking corn in water, which produces potassium dihydrogen phosphate with fewer impurities and meets the quality standards of the pharmaceutical industry, in order to address the shortcomings of the existing technology.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water includes the following steps:

[0007] A: The corn soaking water is passed through an anion exchange resin column to adsorb phytic acid, and then the anion exchange resin column is desorbed using potassium chloride solution to obtain the eluent.

[0008] B: The eluent is concentrated using a nanofiltration membrane to obtain nanofiltration concentrate. The main component of the nanofiltration clear liquid is potassium chloride, which is recovered and used to prepare potassium chloride solution.

[0009] C: The nanofiltration concentrate enters the hydrolysis tank and is hydrolyzed to obtain hydrolysate;

[0010] D: After the hydrolysate is cooled to 50-60℃, it is filtered. The filtrate is then introduced into a simulated moving bed chromatography device to separate the potassium dihydrogen phosphate phase and the inositol phase.

[0011] E: The potassium dihydrogen phosphate phase enters the hydrogen-type chelate cation exchange resin column, and the effluent enters the multi-effect concentration system. The potassium dihydrogen phosphate concentrate is concentrated at a vacuum of -0.09 to -0.1 MPa and a temperature of 80 to 90°C.

[0012] F: Add activated carbon to the potassium dihydrogen phosphate concentrate, decolorize, and then filter to obtain the decolorized solution;

[0013] G: The decolorized filtrate enters the crystallization tank, and the cooling rate is controlled at 5℃ / h. After crystals appear, the temperature is maintained for 1h, and the temperature is reduced to 30-40℃. The liquid is then transferred to a centrifuge for dehydration. After dehydration, the wet product is added to an ethanol solution, kept warm and stirred, and then centrifuged a second time to obtain wet potassium dihydrogen phosphate.

[0014] H: Wet potassium dihydrogen phosphate is dried in a vibrating fluidized bed to obtain potassium dihydrogen phosphate product.

[0015] Preferably, the solid content of the corn soaking water in step A is 10-15% w / w, and the feeding rate is 2-3 BV / h;

[0016] The concentration of potassium chloride solution is 10-15% g / L, the amount added is 1.5-2.5 BV, and the feed rate is 1-2 BV / h.

[0017] Preferably, the molecular weight cutoff of the nanofiltration membrane in step B is 200-500 Da.

[0018] Preferably, in step C, the nanofiltration concentrate is hydrolyzed in a hydrolysis tank at 160–180°C and 0.6–0.8 MPa for 8–12 hours, or hydrolyzed in a hydrolysis tank at 60–80°C and pH 4–6 with the addition of phytase for 10–15 hours. The amount of phytase used is 2–5‰ w / w of the nanofiltration concentrate, and the enzyme activity of phytase is 50,000–100,000 units / gram.

[0019] Preferably, in step D, the inositol phase is first concentrated in a multi-effect concentrator at a vacuum of -0.07 to -0.09 MPa and a temperature of 75 to 90°C to a solid content of 40 to 50% w / w, to obtain an inositol concentrate. Then, 2 to 4% w / w of activated carbon by weight of the inositol concentrate is added for decolorization. After filtration, the concentrate is cooled and crystallized in a crystallizer at a controlled cooling rate of 5 to 8°C / h. After cooling to 35°C, the concentrate is centrifuged. The centrifuged wet product is dried and pulverized to obtain the inositol product.

[0020] Preferably, the hydrogen-form chelating cation exchange resin column in step E is a macroporous cation exchange resin column containing aminomethyl phosphate groups, which is converted to hydrogen form using hydrochloric acid before use.

[0021] Preferably, in step E, the feed rate of the potassium dihydrogen phosphate phase is 1.5–2.5 BV / h, the pH of the effluent is between 1.0 and 1.5, the solid content of the potassium dihydrogen phosphate concentrate is 35–40% w / w, and the pH of the potassium dihydrogen phosphate concentrate is between 3.5 and 4.5.

[0022] Preferably, in step F, the amount of activated carbon added is 3-5% w / w to the mass ratio of the concentrated solution, the decolorization temperature is 60-80℃, the decolorization time is 0.5-1h, and the transmittance of the decolorized solution is ≥95%.

[0023] Preferably, in step G, the ratio of the amount of ethanol solution added to the mass of the wet product is 2-3:1 w / w, the concentration of the ethanol solution is 90-98% w / w, the wet product is kept at a temperature of 50-60°C after being added to the ethanol solution, the holding time is 1-2 hours, and the stirring speed is 30-60 rpm.

[0024] Preferably, in step H, the inlet air temperature of the vibrating fluidized bed is 120–150°C, the outlet air temperature is 60–80°C, and the moisture content after drying is ≤0.1%.

[0025] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0026] 1. Potassium dihydrogen phosphate is used to selectively adsorb divalent and polyvalent metal ions through a hydrogen-type chelating cation exchange resin column, thereby achieving the removal of calcium, magnesium and heavy metal ions.

[0027] 2. After the potassium dihydrogen phosphate phase is passed through a weakly acidic hydrogen-type chelating cation exchange resin column to remove polyvalent metal ions, the acidity of the solution increases. Under acidic conditions, the residual chloride ions are concentrated under vacuum and volatilized as HCl. After being cooled by the condensation system, they remain in the steam condensate, thus achieving the removal of chloride ions.

[0028] 3. The organic impurities in corn soaking water are complex and easily remain in potassium dihydrogen phosphate, causing the potassium dihydrogen phosphate product to turn yellow after drying, affecting product quality. Although activated carbon adsorption and decolorization after concentration can remove some organic impurities, the removal is not thorough. Adding the wet crystalline potassium dihydrogen phosphate to an ethanol solution utilizes the characteristic that potassium dihydrogen phosphate is insoluble in ethanol, while organic impurities are soluble in ethanol, to remove organic impurities such as proteins, polysaccharides, and lactic acids, achieving complete purification of the potassium dihydrogen phosphate.

[0029] 4. The obtained potassium dihydrogen phosphate product is of high quality and meets pharmaceutical-grade product standards. Detailed Implementation

[0030] The present invention will be further illustrated below with reference to the embodiments.

[0031] Example 1

[0032] a. Potassium phytate adsorption and desorption: 80m 3 Corn soaking water (15% w / w solids, 1.5% w / w phytic acid) was passed through a 10m channel at a flow rate of 2 BV / h. 3 A weakly basic anion exchange resin column was used. The saturated resin was washed with 3 BV of water to remove surface impurities. Then, phytic acid adsorbed on the column was eluted with a potassium chloride solution (10% g / L, 2.5 BV of resin volume) at a rate of 2 BV / h, yielding 25 mL of dilute potassium phytate solution. 3 .

[0033] b. Potassium phytate concentration: The dilute potassium phytate solution obtained in step a is concentrated using a nanofiltration membrane to obtain a 6.0 mL potassium phytate concentrate with a concentration of 23% g / L. 3 Nanofiltration membranes have a molecular weight cutoff of 500 Da;

[0034] c. Potassium phytate hydrolysis: The concentrated potassium phytate solution obtained in step b is added to a hydrolysis reactor, steam is introduced, and the mixture is heated to 160℃ and 0.6MPa. This temperature and pressure are maintained for 12 hours until hydrolysis is complete, yielding 7.0 ml of hydrolysate. 3 ;

[0035] d. Separation: The hydrolysate obtained in step c is cooled by flash evaporation to a temperature of 50°C. After cooling, the solution is filtered using a plate and frame filter press, and the filtrate is fed into a simulated moving bed chromatography apparatus for separation. The packing material of the simulated moving bed chromatography apparatus is a strongly acidic cation exchange resin, and the mobile phase is purified water. The separation conditions are: temperature 50°C, pressure 0.1 MPa, valve switching time 10 min, and feed flow rate 5 m / s. 3 / h, the flow rate of the mobile phase is 10m. 3 / h. 9.0m of inositol solution was obtained after separation. 3 18.0 ml of potassium dihydrogen phosphate solution 3 ;

[0036] e. Concentration: The potassium dihydrogen phosphate solution separated in step d is first fed into a hydrogen-form chelating cation exchange resin column with a bed volume of 4 m³. 3 The feed flow rate was 1.5 BV / h, and the effluent pH was 1.5. The effluent was concentrated in a plate-type four-effect concentrator under a vacuum of -0.07 MPa and a temperature of 90℃, yielding 2.5 m³ of concentrated solution. 3 It has a solid content of 40% w / w and a pH of 4.5.

[0037] f. Decolorization and filtration: Add activated carbon to the concentrate from step e, at a dosage of 3% w / w of the concentrate volume, decolorize at 80°C for 1 hour, and filter using a candle filter to obtain 2.5 ml of decolorized filtrate. 3 The filtrate has a light transmittance of 95%.

[0038] g. Preparation of wet potassium dihydrogen phosphate: The decolorized filtrate obtained in step f was placed in a crystallizer and cooled for crystallization at a cooling rate of 5℃ / h. After crystals appeared, the solution was kept at this temperature for 1h, cooled to 30℃, and centrifuged to obtain 970kg of wet potassium dihydrogen phosphate. After centrifugation, the wet product was added to 1950kg of 90% w / w ethanol solution, kept at 50℃ with stirring for 1h, and then centrifuged a second time to obtain 960kg of wet potassium dihydrogen phosphate.

[0039] h. Drying and packaging: The wet potassium dihydrogen phosphate obtained in step g is dried in a fluidized bed, with the inlet air temperature controlled at 120℃ and the outlet air temperature at 60℃. After pulverization and packaging, the potassium dihydrogen phosphate product with a weight of 920kg is obtained.

[0040] i. Inositol preparation: The inositol solution separated in step d is first concentrated using a plate-type four-effect concentrator under a vacuum of -0.07 MPa and a temperature of 90°C, yielding a concentrate of 0.55 ml. 3 The solid content is 50%. Then, activated carbon is added at a rate of 2% w / w of the liquid volume for decolorization. After filtration through a candle filter, the liquid is cooled and crystallized in a crystallizer at a cooling rate of 8℃ / h. After cooling to 35℃, the liquid is centrifuged to obtain 220kg of wet inositol. The centrifuged wet product is then dried in a fluidized bed with the inlet air temperature controlled at 140℃ and the outlet air temperature at 75℃. After pulverization, packaging, and other processes, the inositol product weighing 205kg is obtained.

[0041] Example 2

[0042] a. Potassium phytate adsorption and desorption: 80m 3 Corn soaking water (solid content 10% w / w, phytic acid content 1.4% w / w) was passed through a 10m channel at a flow rate of 3 BV / h. 3 A weakly basic anion exchange resin column was used. The saturated resin was washed with 3 BV of water to remove surface impurities. Then, phytic acid adsorbed on the resin was eluted with a potassium chloride solution (15% g / L, 1.5 BV of resin volume) at a rate of 1 BV / h, yielding 15 mL of dilute potassium phytate solution. 3 .

[0043] b. Potassium phytate concentration: The dilute potassium phytate solution obtained in step a is concentrated using a nanofiltration membrane to obtain a 7.0 m³ potassium phytate concentrate with a concentration of 20% g / L. 3 Nanofiltration membranes have a molecular weight cutoff of 200 Da;

[0044] c. Potassium phytate hydrolysis: The concentrated potassium phytate solution obtained in step b is added to a hydrolysis reactor, steam is introduced, and the mixture is heated to 180℃ and 0.8MPa. This temperature and pressure are maintained for 8 hours until hydrolysis is complete, yielding 8.0 ml of hydrolysate. 3 ;

[0045] d. Separation: The hydrolysate obtained in step c is cooled by flash evaporation to a temperature of 60°C. The flash-evaporated solution is filtered using a plate and frame filter press, and the filtrate is then subjected to separation in a simulated moving bed chromatography system. The simulated moving bed chromatography packing material is a strongly acidic cation exchange resin, and the mobile phase is purified water. The separation conditions are: temperature 50°C, pressure 0.1 MPa, valve switching time 10 min, and feed flow rate 5 m / s. 3 / h, the flow rate of the mobile phase is 10m. 3 / h. 10.5m of inositol solution was obtained through separation. 3 17.5 ml of potassium dihydrogen phosphate solution 3 ;

[0046] e. Concentration: The potassium dihydrogen phosphate solution separated in step d is first fed into a hydrogen-form chelating cation exchange resin column with a bed volume of 4 m³. 3 The feed flow rate was 2.5 BV / h, and the effluent pH was 1.0. The effluent was concentrated in a plate-type quadruple-effect concentrator under a vacuum of -0.09 MPa and a temperature of 80°C, yielding 3 ml of concentrated liquid. 3 It has a solid content of 35% w / w and a pH of 3.5.

[0047] f. Decolorization and filtration: Add activated carbon to the concentrate from step e, at a dosage of 5% w / w of the feed volume, decolorize at 60℃ for 0.5 h, and filter using a candle filter to obtain 3 ml of decolorized filtrate. 3 The filtrate has a light transmittance of 98%.

[0048] g. Preparation of wet potassium dihydrogen phosphate: The decolorized filtrate obtained in step f was placed in a crystallizer and cooled for crystallization at a cooling rate of 5℃ / h. After crystals appeared, the solution was kept at this temperature for 1h, cooled to 40℃, and centrifuged to obtain 950kg of wet potassium dihydrogen phosphate. After centrifugation, the wet product was added to 2850kg of 98% w / w ethanol solution, kept at 60℃ with stirring for 2h, and then centrifuged again to obtain 940kg of wet potassium dihydrogen phosphate.

[0049] h. Drying and packaging: The wet potassium dihydrogen phosphate obtained in step g is dried in a fluidized bed (inlet air temperature 150℃, outlet air temperature 80℃), pulverized, and packaged to obtain the potassium dihydrogen phosphate product, weighing 910kg.

[0050] i. Inositol preparation: The inositol solution separated in step d was first concentrated using a plate-type four-effect concentrator under a vacuum of -0.09 MPa and a temperature of 75°C, yielding a concentrate of 0.65 mL. 3The solid content is 40% w / w. Then, activated carbon is added at a rate of 4% w / w of the liquid volume for decolorization. After filtration through a candle filter, the solution is cooled and crystallized in a crystallization tank at a cooling rate of 5℃ / h. After cooling to 35℃, the solution is centrifuged to obtain 220 kg of wet inositol. The centrifuged wet product is then subjected to fluidized bed drying (inlet air temperature 140℃, outlet air temperature 75℃), pulverization, and packaging to obtain the inositol product weighing 200 kg.

[0051] Example 3

[0052] a. Potassium phytate adsorption and desorption: 80m 3 Corn soaking water (solid content 13% w / w, phytic acid content 1.5% w / w) was passed through a 10m channel at a flow rate of 2.5 BV / h. 3 A weakly basic anion exchange resin column was used. The saturated resin was washed with 3 BV of water to remove surface impurities. Then, phytic acid adsorbed on the resin was eluted with a potassium chloride solution (12% g / L, 2 BV of resin volume) at a rate of 1.5 BV / h, yielding 20 mL of dilute potassium phytate solution. 3 .

[0053] b. Potassium phytate concentration: The dilute potassium phytate solution obtained in step a is concentrated using a nanofiltration membrane to obtain a 6.5m solution of potassium phytate concentrate with a concentration of 22% g / L. 3 Nanofiltration membrane has a molecular weight cutoff of 300D;

[0054] c. Potassium phytate hydrolysis: The concentrated potassium phytate solution obtained in step b is added to a hydrolysis reactor, steam is introduced, and the mixture is heated to 170℃ and 0.7MPa. This temperature and pressure are maintained for 10 hours until hydrolysis is complete, yielding 7.5 ml of hydrolysate. 3 ;

[0055] d. Separation: The hydrolysate obtained in step c is cooled by flash evaporation to a temperature of 55°C. The flash-evaporated solution is filtered using a plate and frame filter press, and the filtrate is then subjected to separation in a simulated moving bed chromatography system. The simulated moving bed chromatography packing material is a strongly acidic cation exchange resin, and the mobile phase is purified water. The separation conditions are: temperature 50°C, pressure 0.1 MPa, valve switching time 10 min, and feed flow rate 5 m / s. 3 / h, the flow rate of the mobile phase is 10m. 3 / h. 11.5m of inositol solution was obtained after separation. 3 18.5 ml of potassium dihydrogen phosphate solution 3 ;

[0056] e. Concentration: The potassium dihydrogen phosphate solution separated in step d is first fed into a hydrogen-form chelating cation exchange resin column with a bed volume of 4 m³. 3The feed flow rate was 2 BV / h, and the effluent pH was 1.3. The effluent was concentrated in a plate-type four-effect concentrator under a vacuum of -0.08 MPa and a temperature of 85°C, yielding 2.8 m³ of concentrated liquid. 3 It has a solid content of 38% w / w and a pH of 3.8.

[0057] f. Decolorization and filtration: Activated carbon is added to the concentrate from step e, at a dosage of 4% w / w of the feed volume. Decolorization is carried out at 70℃ for 0.75 h. The solution is then filtered using a candle filter to obtain 2.8 ml of decolorized filtrate. 3 The filtrate has a light transmittance of 97%.

[0058] g. Preparation of wet potassium dihydrogen phosphate: The decolorized filtrate obtained in step f was placed in a crystallizer and cooled for crystallization at a cooling rate of 5℃ / h. After crystals appeared, the solution was kept at this temperature for 1h, cooled to 35℃, and centrifuged to obtain 980kg of wet potassium dihydrogen phosphate. After centrifugation, the wet product was added to 2450kg of 95% w / w ethanol solution, kept at 55℃ with stirring for 1.5h, and then centrifuged a second time to obtain 970kg of wet potassium dihydrogen phosphate.

[0059] h. Drying and packaging: The wet potassium dihydrogen phosphate obtained in step g is dried in a fluidized bed (inlet air temperature 140℃, outlet air temperature 70℃), pulverized, and packaged to obtain the potassium dihydrogen phosphate product, weighing 940kg.

[0060] i. Inositol preparation: The inositol solution separated in step d was first concentrated using a plate-type four-effect concentrator under a vacuum of -0.08 MPa and a temperature of 85°C, yielding a concentrate of 0.6 m³. 3 The solid content was 45% w / w. Then, activated carbon was added at a rate of 3% w / w of the liquid volume for decolorization. After filtration through a candle filter, the solution was cooled and crystallized in a crystallizer at a cooling rate of 5℃ / h. After cooling to 35℃, the solution was centrifuged to obtain 220 kg of wet inositol. The centrifuged wet product was then subjected to fluidized bed drying (inlet air temperature 140℃, outlet air temperature 75℃), pulverization, and packaging to obtain the inositol product, weighing 210 kg.

[0061] Example 4

[0062] a. Potassium phytate adsorption and desorption: 80m 3 Corn soaking water (solid content 13% w / w, phytic acid content 1.5% w / w) was passed through a 10m channel at a flow rate of 2.5 BV / h. 3 A weakly basic anion exchange resin column was used. The saturated resin was washed with 3 BV of water to remove surface impurities. Then, phytic acid adsorbed on the resin was eluted with a potassium chloride solution (12% g / L, 2 BV of resin volume) at a rate of 1.5 BV / h, yielding 20 mL of dilute potassium phytate solution. 3 .

[0063] b. Potassium phytate concentration: The dilute potassium phytate solution obtained in step a is concentrated using a nanofiltration membrane to obtain a 6.5m solution of potassium phytate concentrate with a concentration of 22% g / L. 3 Nanofiltration membrane has a molecular weight cutoff of 300D;

[0064] c. Potassium phytate hydrolysis: The concentrated potassium phytate solution obtained in step b is added to a hydrolysis reactor, steam is introduced, and the temperature is heated to 60°C. Phytase (5‰ w / w) with an activity of 50,000 units / g is added, and the mixture is kept at this temperature for 10 hours until hydrolysis is complete, yielding 6.5 ml of hydrolysate. 3 ;

[0065] d. Separation: The hydrolysate obtained in step c was filtered using a plate and frame filter press. The filtrate was then subjected to separation using a simulated moving bed chromatography system. The simulated moving bed chromatography packing material was a strongly acidic cation exchange resin, and the mobile phase was purified water. The separation conditions were: temperature 50℃, pressure 0.1MPa, valve switching time 10min, and feed flow rate 5m / min. 3 / h, the flow rate of the mobile phase is 10m. 3 / h. 10.5m of inositol solution was obtained after separation. 3 17.5 ml of potassium dihydrogen phosphate solution 3 ;

[0066] e. Concentration: The potassium dihydrogen phosphate solution separated in step d is first fed into a hydrogen-form chelating cation exchange resin column with a bed volume of 4 m³. 3 The feed flow rate was 2 BV / h, and the effluent pH was 1.3. The effluent was concentrated in a plate-type four-effect concentrator under a concentration vacuum of -0.08 MPa and a temperature of 85°C, yielding 2.9 m³ of concentrated liquid. 3 It has a solid content of 36.5% w / w and a pH of 4.0.

[0067] f. Decolorization and filtration: Activated carbon is added to the concentrate from step e, at a dosage of 4% w / w of the feed volume. Decolorization is carried out at 70℃ for 0.75 h. The solution is then filtered using a candle filter to obtain 2.9 ml of decolorized filtrate. 3 The filtrate has a light transmittance of 98%.

[0068] g. Preparation of wet potassium dihydrogen phosphate: The decolorized filtrate obtained in step f was placed in a crystallizer and cooled for crystallization at a cooling rate of 5℃ / h. After crystals appeared, the solution was kept at this temperature for 1h, cooled to 35℃, and centrifuged to obtain 970kg of wet potassium dihydrogen phosphate. After centrifugation, the wet product was added to 2400kg of 95% w / w ethanol solution, kept at 55℃ with stirring for 1.5h, and then centrifuged a second time to obtain 950kg of wet potassium dihydrogen phosphate.

[0069] h. Drying and packaging: The wet potassium dihydrogen phosphate obtained in step g is dried in a fluidized bed (inlet air temperature 140℃, outlet air temperature 70℃), pulverized, and packaged to obtain the potassium dihydrogen phosphate product with a weight of 930kg.

[0070] i. Inositol preparation: The inositol solution separated in step d was first concentrated using a plate-type four-effect concentrator under a vacuum of -0.08 MPa and a temperature of 85°C, yielding a concentrate of 0.6 m³. 3 The solid content was 45% w / w. Then, activated carbon was added at a rate of 3% w / w of the liquid volume for decolorization. After filtration through a candle filter, the solution was cooled and crystallized in a crystallizer at a cooling rate of 5℃ / h. After cooling to 35℃, the solution was centrifuged to obtain 215 kg of wet inositol. The centrifuged wet product was then subjected to fluidized bed drying (inlet air temperature 140℃, outlet air temperature 75℃), pulverization, and packaging to obtain the inositol product, weighing 208 kg.

[0071] Comparative Example 1

[0072] Step e in Example 1 was removed, while other conditions remained unchanged. 930 kg of potassium dihydrogen phosphate and 206 kg of inositol were obtained.

[0073] Comparative Example 2

[0074] In Example 2, step e, the hydrogen-form chelating cation exchange resin column was replaced with an equal amount of potassium-form chelating cation exchange resin column, while other conditions remained unchanged. The resulting product weighed 915 kg of potassium dihydrogen phosphate and 198 kg of inositol.

[0075] Comparative Example 3

[0076] The ethanol washing step in step g of Example 3 was removed, while other conditions remained unchanged. 945 kg of potassium dihydrogen phosphate and 211 kg of inositol were obtained.

[0077] Comparative Example 4

[0078] In step g of Example 4, the 95% w / w ethanol was replaced with an equal amount of 50% w / w ethanol, while other conditions remained unchanged. The resulting product weighed 650 kg of potassium dihydrogen phosphate and 206 kg of inositol.

[0079] Results analysis:

[0080] The product data obtained from Examples 1-4 and Comparative Examples 1-4 were analyzed. The detection of potassium dihydrogen phosphate was performed according to the methods in Part IV of the 2020 edition of the Pharmacopoeia of the People's Republic of China. The results are shown in Table 1.

[0081] Table 1. Detection results of potassium dihydrogen phosphate obtained from Examples 1-4 and Comparative Examples 1-4.

[0082]

[0083] The results of potassium dihydrogen phosphate detection in the examples and comparative examples show that:

[0084] In Comparative Example 1, after removing step e of Example 1, the residual polyvalent metal ions in the feed solution could not be removed, resulting in an increase in water-insoluble matter in the product; at the same time, the chloride content in the feed solution exceeded the standard. This was because the feed solution was not treated with cation exchange resin, and the pH of the feed solution was 4.0-4.5. During the vacuum evaporation and concentration process, less chloride ions escaped.

[0085] In Comparative Example 2, the hydrogen-type chelating cation exchange resin column in step e of Example 2 was replaced with an equal amount of potassium-type chelating cation exchange resin column. Although it could also remove polyvalent metal ions, it could not adjust the pH, resulting in excessive chloride in the product.

[0086] After the ethanol washing process in step g of Example 3 was removed, the product dried in Comparative Example 3 turned yellow and had a lower potassium dihydrogen phosphate content, indicating that ethanol washing can effectively remove organic impurities carried in the wet product and improve product quality.

[0087] In Comparative Example 4, after replacing the 95% w / w ethanol in step g of Example 4 with an equal amount of 50% w / w ethanol, the loss of potassium dihydrogen phosphate was significant because the low concentration of ethanol can dissolve potassium dihydrogen phosphate. At the same time, the low concentration of ethanol is highly polar and has a poor washing effect on weakly polar organic impurities, thus failing to effectively improve the purity of the product.

[0088] Inositol was tested according to the methods in Part IV of the 2020 edition of the Pharmacopoeia of the People's Republic of China. The test results of Examples 1-4 and Comparative Examples 1-4 all met the standard requirements.

[0089] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water, characterized in that... Includes the following steps: A: The corn soaking water is passed through an anion exchange resin column to adsorb phytic acid, and then the anion exchange resin column is desorbed using potassium chloride solution to obtain the eluent. B: The eluent is concentrated using a nanofiltration membrane to obtain nanofiltration concentrate. The main component of the nanofiltration clear liquid is potassium chloride, which is recovered and used to prepare potassium chloride solution. C: The nanofiltration concentrate enters the hydrolysis tank and is hydrolyzed to obtain hydrolysate; D: After the hydrolysate is cooled to 50-60℃, it is filtered. The filtrate is then introduced into a simulated moving bed chromatography device to separate the potassium dihydrogen phosphate phase and the inositol phase. E: The potassium dihydrogen phosphate phase enters the hydrogen-form chelate cation exchange resin column, and the effluent enters the multi-effect concentration system. The potassium dihydrogen phosphate concentrate is concentrated at a vacuum of -0.09 to -0.1 MPa and a temperature of 80 to 90°C. The hydrogen-form chelate cation exchange resin column is a macroporous cation exchange resin column containing aminomethyl phosphate groups. Before use, it is converted to hydrogen form using hydrochloric acid. F: Add activated carbon to the potassium dihydrogen phosphate concentrate, decolorize, and then filter to obtain the decolorized solution; G: The decolorized filtrate enters the crystallization tank, and the cooling rate is controlled at 5℃ / h. After crystals appear, the temperature is maintained for 1h, and the temperature is lowered to 30-40℃. The liquid is then transferred to a centrifuge for dehydration. After dehydration, the wet product is added to an ethanol solution, kept warm and stirred, and then centrifuged a second time to obtain potassium dihydrogen phosphate wet product. The concentration of the ethanol solution is 90-98% w / w. After the wet product is added to the ethanol solution, the temperature is maintained at 50-60℃ for 1-2h, and the stirring speed is 30-60 rpm. H: Wet potassium dihydrogen phosphate is dried in a vibrating fluidized bed to obtain potassium dihydrogen phosphate product.

2. The process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water as described in claim 1, characterized in that: In step A, the solid content of the corn soaking water is 10-15% w / w, and the feed rate is 2-3 BV / h; The concentration of potassium chloride solution is 10-15% g / L, the amount added is 1.5-2.5 BV, and the feed rate is 1-2 BV / h.

3. The process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water as described in claim 1, characterized in that: In step B, the molecular weight cutoff of the nanofiltration membrane is 200–500 Da.

4. The process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water as described in claim 1, characterized in that: In step C, the nanofiltration concentrate is hydrolyzed in a hydrolysis tank at 160–180°C and 0.6–0.8 MPa for 8–12 hours, or hydrolyzed in a hydrolysis tank at 60–80°C and pH 4–6 with the addition of phytase for 10–15 hours. The amount of phytase used is 2–5‰ w / w of the nanofiltration concentrate, and the enzyme activity of phytase is 50,000–100,000 units / gram.

5. The process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water as described in claim 1, characterized in that: In step D, the inositol phase is first concentrated in a multi-effect concentrator at a vacuum of -0.07 to -0.09 MPa and a temperature of 75 to 90°C until the solid content is 40 to 50% w / w, to obtain an inositol concentrate. Then, 2 to 4% w / w of activated carbon by weight of the inositol concentrate is added for decolorization. After filtration, the concentrate is cooled and crystallized in a crystallizer at a controlled cooling rate of 5 to 8°C / h. After cooling to 35°C, the concentrate is centrifuged. The centrifuged wet product is dried and pulverized to obtain the inositol product.

6. The process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water as described in claim 1, characterized in that: In step E, the feed rate of the potassium dihydrogen phosphate phase is 1.5–2.5 BV / h, the pH of the effluent is between 1.0 and 1.5, the solid content of the potassium dihydrogen phosphate concentrate is 35–40% w / w, and the pH of the potassium dihydrogen phosphate concentrate is between 3.5 and 4.

5.

7. The process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water as described in claim 1, characterized in that: In step F, the amount of activated carbon added is 3-5% w / w of the mass ratio of the concentrated solution, the decolorization temperature is 60-80℃, the decolorization time is 0.5-1h, and the transmittance of the decolorized solution is ≥95%.

8. The process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water as described in claim 1, characterized in that: In step G, the ratio of the amount of ethanol solution added to the mass of the wet product is 2-3:1 w / w.

9. The process for producing pharmaceutical-grade potassium dihydrogen phosphate from corn soaking water as described in claim 1, characterized in that: In step H, the inlet air temperature of the vibrating fluidized bed is 120-150℃, the outlet air temperature is 60-80℃, and the moisture content after drying is ≤0.1%.

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