A method for extracting effective components from corn steep liquor

Abstract

The application discloses a method for extracting effective components from corn soaking water, which comprises the following steps: adsorbing phytic acid in the corn soaking water through a resin, obtaining effluent, removing zein and calcium magnesium salt from the effluent to obtain a treatment liquid, filtering and concentrating the treatment liquid through a reverse osmosis membrane to obtain a first cut-off liquid, adding hydrochloric acid into the first cut-off liquid to adjust the pH to 2.0-2.5, vacuum concentrating until crystals are precipitated, closing the vacuum and cooling to crystallize to obtain a KCl crude product and a first filtrate, and distilling the first filtrate to obtain a lactic acid solution and a distillation dry substance. The method effectively separates potassium chloride crude product, the lactic acid solution and the distillation dry substance from the corn soaking water, fully extracts, separates and utilizes the effective components in the corn soaking water, and improves the comprehensive economic benefits of a corn processing industrial chain.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of comprehensive utilization of corn steep liquor, and particularly relates to a method for extracting effective components in corn steep liquor. BACKGROUND

[0002] In the process of producing corn starch by wet milling method, corn steep liquor is the main production wastewater. Generally, about 0.8 tons of corn steep liquor is generated for treating 1 ton of corn. China is the largest corn starch producing country in the world, and about 300 million tons of corn starch is produced every year, most of which is produced by wet method, and about 35 million tons of corn steep liquor is generated every year. The corn steep liquor contains protein, phytic acid, lactic acid, sugar, starch residue and inorganic salt.

[0003] In the prior art, the corn steep liquor is treated by being introduced into anion resin to adsorb phytic acid, and the phytic acid is desorbed to obtain potassium phytate; the effluent is first filtered by ceramic membrane to remove macromolecular crude protein and large particle impurities, and then concentrated by nanofiltration membrane, and the retentate is sprayed and dried to obtain a corn protein product; and the permeate is concentrated to a solid content of 30-35% by reverse osmosis membrane, and sold in the form of organic fertilizer.

[0004] In the above method for treating corn steep liquor, the permeate after nanofiltration membrane concentration still contains a large amount of valuable substances which are not fully utilized, and there is a safety risk that aflatoxin and vomitoxin cannot be completely removed.

[0005] Therefore, it is urgent to establish a method for fully utilizing the components in corn steep liquor in the prior art to improve the comprehensive economic benefit of the corn processing industry chain. SUMMARY

[0006] Therefore, the present application aims to provide a method for extracting effective components in corn steep liquor, which overcomes the technical defects that the effective components in corn steep liquor are not effectively extracted and fully utilized in the prior art, fully separates and utilizes the effective components in corn steep liquor, and improves the comprehensive economic benefit of the corn processing industry chain.

[0007] In order to achieve the above-mentioned purpose, the present application provides a method for extracting effective components in corn steep liquor, comprising the following steps:

[0008] adsorbing phytic acid in the corn steep liquor by anion exchange resin to obtain effluent;

[0009] treating the effluent by removing corn protein and removing calcium and magnesium salt to obtain a treatment liquid;

[0010] introducing the treatment liquid into a reverse osmosis membrane with a molecular weight cut-off of 50-100 Da to obtain a first retentate and a permeate.

[0011] The first retentate is kept at 120-140 DEG C and 0.2-0.3 MPa for 0.5-2 h, and then cooled to below 100 DEG C under normal pressure, and hydrochloric acid is added to adjust the pH to 2.0-2.5, and then concentrated under vacuum until crystals precipitate in the solution to obtain a concentrated solution;

[0012] The concentrated solution is cooled to 30 DEG C for crystallization, and after the crystallization is completed, first filtration is performed to obtain KCl crude product and a first filtrate;

[0013] The first filtrate is distilled, and a fraction under the condition of 82-85 DEG C / 100 Pa is collected to obtain a lactic acid solution and a distillation dry substance.

[0014] The present application provides a method for extracting effective components from corn soaking water, which comprises the following steps: first, using anion exchange resin to adsorb phytic acid in the corn soaking water to remove the phytic acid in the corn soaking water; the effluent after adsorption is treated by removing corn protein and removing calcium and magnesium salts to obtain a treated solution, thereby realizing preliminary separation of impurities; the treated solution is concentrated by a reverse osmosis membrane to obtain a first retentate; the first retentate is adjusted to a pH of 2.0-2.5 by adding hydrochloric acid, so that the potassium lactate in the solution is converted into lactic acid and potassium chloride, thereby preparing for subsequent separation of potassium chloride and lactic acid; when crystals precipitate during vacuum concentration, the vacuum is closed and cooling crystallization is performed, so that potassium chloride is precipitated to obtain potassium chloride crude product and a first filtrate; the main components in the first filtrate include lactic acid and protein small peptides, and a lactic acid solution and a distillation dry substance can be obtained by high-vacuum distillation, wherein the distillation dry substance is a mixture of solid small peptides. The present application separates and prepares potassium chloride crude product, a lactic acid solution and a distillation dry substance (small peptide product) from corn soaking water, fully extracts, separates and utilizes the effective components in the corn soaking water, enriches the utilization ways of corn soaking water, and improves the comprehensive economic benefits of the corn processing industry chain. DETAILED DESCRIPTION

[0015] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, the present application will be further described in detail below in combination with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0016] The present application provides a method for extracting effective components from corn soaking water, which comprises the following steps:

[0017] The corn soaking water is adsorbed by anion exchange resin to remove phytic acid, thereby obtaining an effluent;

[0018] The effluent is treated by removing corn protein and removing calcium and magnesium salts to obtain a treated solution;

[0019] The treatment liquid enters a reverse osmosis membrane with a molecular weight cut-off of 50-100 Da to obtain a first cut-off liquid and a permeate liquid;

[0020] The first cut-off liquid is kept at 120-140 DEG C and 0.2-0.3 MPa for 0.5-2 h, and then cooled to below 100 DEG C under normal pressure, and hydrochloric acid is added to adjust the pH to 2.0-2.5, and then concentrated under vacuum until crystals precipitate in the solution to obtain a concentrated liquid;

[0021] The concentrated liquid is cooled to 30 DEG C for crystallization, and after the crystallization is completed, a first filtration is performed to obtain a KCl crude product and a first filtrate;

[0022] The first filtrate is distilled, and a fraction under the condition of 82-85 DEG C / 100 Pa is collected to obtain a lactic acid solution and a distilled dry substance.

[0023] In the present application, the anion exchange resin is preferably a macroporous weakly basic anion exchange resin, such as D301, D354, D370, and D351; the feed amount of the corn soaking water is preferably 6-10 BV of the volume of the anion exchange resin, and the feed speed is preferably 1-2 BV / h. The present application does not have special limitations on the feeding mode of the corn soaking water, and a commonly used method in the art can be used, such as pump feeding; the present application does not have special limitations on the carrier of the resin, and a commonly used carrier in the art can be used, such as a resin column. It should be understood that the purpose of the adsorption of the anion exchange resin is to adsorb and remove phytic acid in the corn soaking water, and the effluent after the adsorption of the resin is the corn soaking liquid after the removal of phytic acid.

[0024] Further, the present application further comprises: pretreating the corn steep liquor to remove impurities before the corn steep liquor is adsorbed by the anion exchange resin. In the present application, the pretreatment preferably comprises standing at 45-50℃, using a hydrocyclone or using a microfiltration membrane to remove impurities. The standing time for removing impurities is preferably 4-6h; the working parameters of the hydrocyclone are preferably: ratio of the body diameter to the overflow pipe diameter (2-3):1, ratio of the underflow to the feed (1:(20-30)); the pore size of the microfiltration membrane is preferably 0.5-1um. It should be understood that the pretreatment step of the present application before the corn steep liquor is fed to the resin adsorption is mainly to remove solid impurities such as starch and corn husks suspended in the solution. Therefore, the present application can use standing to remove impurities by natural sedimentation under the action of gravity, or use a hydrocyclone to separate suspended impurities from the suspension by centrifugal sedimentation, or use membrane filtration to separate the above impurities from the solution. The separated suspended impurities can be returned to the corn starch plant for preparation of corn yellow syrup powder after concentration, realizing economic utilization of waste materials.

[0025] After the effluent is obtained by adsorption by the anion exchange resin, the present application subjects the effluent to corn protein removal and calcium and magnesium salt removal to obtain a treated liquid. In the present application, the treatment of the effluent to remove corn crude protein and calcium and magnesium salt to obtain a treated liquid comprises: adding potassium hydroxide to the effluent to adjust the pH to 12-13, and obtaining a filter cake containing crude protein and calcium and magnesium salt and a treated liquid by a second filtration. In the present application, the potassium hydroxide is preferably solid potassium hydroxide or a potassium hydroxide solution with a mass concentration of 30-45%, more preferably solid potassium hydroxide; the purpose of adding potassium hydroxide is threefold: first, to adjust the pH of the solution to promote the sedimentation / precipitation and separation of protein and calcium and magnesium salt; second, to add potassium ions to the solution to provide a material basis for the subsequent preparation of potassium chloride product; third, to keep the pH of the filtrate alkaline, which, combined with the subsequent heating to 120-140℃ and 0.2-0.3Mpa holding conditions, can effectively destroy and inactivate aflatoxin and vomitoxin, reducing and eliminating the toxicity of aflatoxin and vomitoxin. In the present application, the pore size of the second filtration is preferably 20-80um, and the present application does not have special limitations on the equipment for the second filtration, which can be a centrifuge, for example.

[0026] Further, after obtaining the treatment liquid, the application further comprises: treating the treatment liquid through a nanofiltration membrane with a molecular weight cut-off of 450-550 Da to obtain a second cut-off liquid containing corn protein and a treatment liquid treated by the nanofiltration membrane, after the treatment liquid is treated to remove corn protein and calcium and magnesium salt to obtain the treatment liquid, and before the treatment liquid enters the reverse osmosis membrane with a molecular weight cut-off of 50-100 Da. In the application, after obtaining the second cut-off liquid containing corn protein, the second cut-off liquid is incubated at 120-140 ℃ and 0.2-0.3 MPa for 0.5-2 h, and then cooled to below 100 ℃ under normal pressure, a small amount of concentrated hydrochloric acid is added to adjust the pH to neutral, and then spray drying treatment is performed to obtain a corn protein powder product; the inlet air temperature of the spray drying is preferably 120-140 ℃, and the outlet air temperature is preferably 90-100 ℃.

[0027] After obtaining the treatment liquid or the treatment liquid treated by the nanofiltration membrane, the application further comprises: treating the treatment liquid or the treatment liquid treated by the nanofiltration membrane through a reverse osmosis membrane with a molecular weight cut-off of 50-100 Da to obtain a first cut-off liquid and a permeate. In the application, the reverse osmosis membrane is mainly used to concentrate the treatment liquid, and preferably, when the refractive solid content of the first cut-off liquid reaches 32-35%, it is considered that the concentration process of the reverse osmosis membrane is completed; the main component of the permeate is water.

[0028] After obtaining the first cut-off liquid, the application further comprises: incubating the first cut-off liquid at 120-140 ℃ and 0.2-0.3 MPa for 0.5-2 h, cooling to below 100 ℃ under normal pressure, adding hydrochloric acid to adjust the pH to 2.0-2.5, and vacuum concentrating to obtain a concentrated liquid with crystals precipitated in the solution. The purpose of incubation in the application is to destroy and inactivate aflatoxin and vomitoxin in the solution under this condition, so as to reduce and eliminate the toxicity of the final product and improve its safety. In the application, the mass concentration of the hydrochloric acid is preferably 25-40%; the vacuum degree of the vacuum concentration is preferably -0.07 MPa to -0.09 MPa, and the temperature is preferably 60-70 ℃. The purpose of vacuum concentration in the application is to improve the concentration of the solution and create conditions for the subsequent cooling and crystallization of potassium chloride.

[0029] After obtaining the concentrated liquid, the application further comprises: cooling the concentrated liquid to 30 ℃ for crystallization, and after the crystallization is completed, first filtering to obtain a KCl crude product and a first filtrate. In the application, the crystallization is preferably cooling crystallization, and the cooling crystallization rate is preferably 5-10 ℃ / h; the filter pore size of the first filtration is preferably 20-80 um, and the application does not have special limitations on the equipment for the first filtration, such as a centrifuge. After obtaining the KCl crude product, the application further comprises washing it with purified water to further remove impurities.

[0030] Further, after obtaining the first filtrate, the application further comprises: adsorbing the first filtrate by strong acid cation resin; desorbing the adsorbed resin by 15-40wt% hydrochloric acid to obtain a desorption solution; mixing the desorption solution with the first retentate and continuing the subsequent steps. The purpose of the cation resin adsorption and desorption in this step is to adsorb and separate potassium chloride in the solution and return to the concentration step before the cooling crystallization. After mixing with the first retentate, the subsequent step is continued to prepare potassium chloride. The potassium chloride that is not crystallized in the first filtrate is further recovered, thereby improving the yield of potassium chloride.

[0031] After obtaining the first filtrate, the application distills the first filtrate to collect the fraction under the condition of 82-85℃ / 100Pa to obtain a lactic acid solution and a distillation dry matter. In the application, distilling the first filtrate to collect the fraction under the condition of 82-85℃ / 100Pa to obtain a lactic acid solution and a distillation dry matter comprises: distilling part of the water in the first filtrate under the condition of -0.09MPa to -0.095Mpa vacuum degree and 60-70℃, and then distilling under the condition of absolute pressure 50-150Pa and 90-100℃, and collecting the lactic acid solution and the distillation dry matter obtained under the condition of 82-85℃ / 100Pa. In the application, the main components of the first filtrate are lactic acid and small peptides. The separation of lactic acid and small peptides in the application is mainly carried out by distillation, which specifically includes two stages: the first stage is to distill 60-75% of the water under the condition of -0.09MPa to -0.095Mpa vacuum degree and 60-70℃. Under this condition, the boiling point of water is reduced, and part of the water can be removed by distillation, which is convenient for subsequent distillation to obtain a lactic acid solution with higher concentration. Under this condition, lactic acid will not be distilled out. The second stage is to increase the temperature to 90-100℃ and the pressure to absolute pressure 50-150Pa. Under this condition, lactic acid and part of the water are evaporated, and the fraction collected under the condition of 82-85℃ / 100Pa can obtain a lactic acid solution. The main component of the distillation dry matter is small peptides.

[0032] Further, after obtaining the distillation dry matter, the application further comprises: dissolving the distillation dry matter with water, decolorizing the solution by activated carbon, and obtaining a decolorized solution by a third filtration, and concentrating the decolorized solution to obtain a small peptide concentrate with a solid content of 30-35%. The application does not have special limitations on the pore size and source of the activated carbon, and the conventional parameters in the field and the commercially available source can be used. The application does not have special limitations on the filter pore size and filter equipment of the third filtration, and the activated carbon after decolorization can be separated from the decolorized solution. The application does not have special limitations on the concentration equipment, and the decolorized solution can be concentrated to a solid content of 30-35%.

[0033] In order to better illustrate the technical scheme of the present application, the present application further provides the following specific examples. It should be understood that the raw materials used in the following examples are all commercially available unless otherwise specified. In particular, the main components of three batches of corn steep liquor are listed in Table 1 below, and the corn steep liquor in the batches is provided by Cixian Haotian Pharmaceutical Co., Ltd.

[0034] Table 11 - Three batches of corn steep liquor

[0035] Batch Protein Lactic acid Phytic acid Sugar Starch residue Inorganic salt Water 1 6.5％ 2.6％ 1.15％ 0.1％ 0.8％ 1.1％ 87.75％ 2 6.4％ 2.5％ 1.15％ 0.1％ 0.9％ 1.0％ 87.95％ 3 6.7％ 2.6％ 1.1％ 0.1％ 0.9％ 1.1％ 87.50％

[0036] Example 1

[0037] S1. Take 660 L of corn steep liquor of batch 1, pass it through 80 L of macroporous weakly basic resin (model D-301) (feed rate of 1.5 BV / h) to adsorb phytic acid, and obtain 625 L of effluent;

[0038] S2. Add 25 kg of solid potassium hydroxide to the effluent to adjust the pH to 12.3, and filter with a 40 um centrifuge to obtain 34.8 kg of filter cake containing crude protein and calcium and magnesium salts, and 612 L of treated liquid;

[0039] S3. The treated liquid enters a reverse osmosis membrane with a molecular weight cut-off of 75 Da to obtain 260 L of first retentate and 352 L of permeate;

[0040] S4. The first retentate is kept at 130℃ and 0.25 MPa for 1 h, cooled to 95℃ at atmospheric pressure, and 30% hydrochloric acid is added to adjust the pH to 2.2, and vacuum concentrated (vacuum degree -0.08 MPa, temperature 65℃) to obtain 125 L of concentrated solution with crystals precipitated in the solution;

[0041] S5. The concentrated solution is cooled at a rate of 8℃ / h, and after the temperature is reduced to 30℃, it is filtered with a 40 um centrifuge to obtain 18.2 kg of KCl crude product (dried, purity 95wt%) and 109 L of first filtrate;

[0042] S6. The first filtrate is distilled at a vacuum degree of -0.09 MPa and a temperature of 65℃ to distill 55 L of water, then distilled at an absolute pressure of 100 Pa and a temperature of 95℃, and the fraction collected at 85℃ / 100 Pa is obtained, to obtain 20 L of lactic acid solution (mass concentration of 48%) and 55.2 kg of distilled dry matter.

[0043] Example 2

[0044] S1. Take 660 L of corn steep liquor of batch 2, pass it through 80 L of macroporous weakly basic resin (model D-354) (feed rate of 1.5 BV / h) to adsorb phytic acid, and obtain 630 L of effluent;

[0045] S2. Add 25.2 kg solid potassium hydroxide to the effluent to adjust the pH to 12.4, and filter through a 60 um centrifuge to obtain 35.0 kg filter cake containing crude protein and calcium and magnesium salts and 615 L treated liquid;

[0046] S3. Treat the treated liquid through a nanofiltration membrane with a 500 Da molecular weight cut-off to obtain 125 L second retentate and 490 L nanofiltration membrane treated liquid;

[0047] S4. Pass the nanofiltration membrane treated liquid through a reverse osmosis membrane with a 75 Da molecular weight cut-off to obtain 240 L first retentate and 250 L permeate;

[0048] S5. Heat the first retentate at 130 °C and 0.25 MPa for 1 h, cool to 95 °C at atmospheric pressure, and add hydrochloric acid with a mass concentration of 30% to adjust the pH to 2.2, and vacuum concentrate (vacuum degree -0.08 MPa, temperature 65 °C) until crystals precipitate in the solution to obtain 91 L concentrated liquid;

[0049] S6. Crystallize the concentrated liquid by cooling at a rate of 8 °C / h, and after the temperature drops to 30 °C, filter through a 60 um centrifuge to obtain 19.0 kg KCl crude product (dry, purity 96 wt%) and 76 L first filtrate;

[0050] S7. Distill 54.5 L water from the first filtrate at a vacuum degree of -0.09 MPa and 65 °C, and then distill at an absolute pressure of 100 Pa and 95 °C, and collect the fraction at 85 °C / 100 Pa to obtain 21.5 L lactic acid solution (mass concentration 50%) and 21.0 kg distillation dry matter.

[0051] Example 3

[0052] S1. Take 660 L corn soaking water from batch 1, and stand at 45 °C for 5 h to obtain 650 L supernatant;

[0053] S2. Adsorb phytic acid from the supernatant through 80 L macroporous weakly basic resin (model D-370) at a feed rate of 1.5 BV / h to obtain 620 L effluent;

[0054] S3. Add 25 kg solid potassium hydroxide to the effluent to adjust the pH to 12.3, and filter through a 70 um centrifuge to obtain 34.6 kg filter cake containing crude protein and calcium and magnesium salts and 610 L treated liquid;

[0055] S4. Treat the treated liquid through a nanofiltration membrane with a 500 Da molecular weight cut-off to obtain 120 L second retentate and 490 L nanofiltration membrane treated liquid;

[0056] S5. The treated solution treated by nanofiltration membrane is fed into a reverse osmosis membrane with a molecular weight cut-off of 75 Da to obtain 240 L of first retentate and 250 L of permeate;

[0057] S6. The first retentate is kept at 130 °C and 0.25 MPa for 1 h, and then cooled to 95 °C under normal pressure, and 30% hydrochloric acid is added to adjust the pH to 2.2, and then concentrated under vacuum (vacuum degree -0.08 MPa, temperature 65 °C) until crystals precipitate in the solution to obtain 90 L of concentrated solution;

[0058] S7. The concentrated solution is cooled at a rate of 8 °C / h, and after the temperature is lowered to 30 °C, it is filtered by a 70 um centrifuge to obtain 19.3 kg of KCl crude product (dry, purity 98 wt%) and 75 L of first filtrate;

[0059] S8. The first filtrate is distilled under the conditions of -0.09 MPa vacuum degree and 65 °C to distill 53 L of water, and then distilled under the conditions of absolute pressure 100 Pa and 95 °C, and the fraction under the conditions of 85 °C / 100 Pa is collected to obtain 22 L of lactic acid solution (mass concentration 50%) and 20.1 kg of distilled dry matter.

[0060] Example 4

[0061] S1. 660 L of corn soaking water of batch 2 is separated by a hydrocyclone (ratio of body diameter to overflow pipe diameter 2.5:1, ratio of underflow to feed 1:25) to obtain 648 L of supernatant;

[0062] S2. The supernatant is adsorbed with phytic acid by 108 L of macroporous weak basic resin (model D-351) at a feed speed of 2 BV / h to obtain 618 L of effluent;

[0063] S3. 24 kg of solid potassium hydroxide is added to the effluent to adjust the pH to 12, and a 20 um centrifuge is used for filtration to obtain 35.0 kg of filter cake containing crude protein and calcium and magnesium salts and 606 L of treated solution;

[0064] S4. The treated solution is treated by a nanofiltration membrane with a molecular weight cut-off of 450 Da to obtain 116 L of second retentate and 490 L of treated solution treated by a nanofiltration membrane;

[0065] S5. The treated solution treated by a nanofiltration membrane is fed into a reverse osmosis membrane with a molecular weight cut-off of 50 Da to obtain 245 L of first retentate and 245 L of permeate;

[0066] S6. The first retentate is kept at 120 °C and 0.3 MPa for 0.5 h, and then cooled to 90 °C under normal pressure, and 40% hydrochloric acid is added to adjust the pH to 2.0, and then concentrated under vacuum (vacuum degree -0.07 MPa, temperature 60 °C) until crystals precipitate in the solution to obtain 90 L of concentrated solution;

[0067] S7. The concentrated solution was cooled at a rate of 5 °C / h, and after the temperature dropped to 30 °C, 20 um centrifuge was used to filter to obtain 19.0 kg of KCl crude product (dried, purity 97wt%) and 73 L of the first filtrate;

[0068] S8. The first filtrate was distilled at a vacuum degree of -0.09 MPa and 60 °C to remove 52 L of water, and then distilled at an absolute pressure of 50 Pa and 90 °C, and the fraction collected at 82 °C / 100 Pa to obtain 21 L of a lactic acid solution (mass concentration of 49%) and 20.5 kg of distilled dry matter.

[0069] Example 5

[0070] S1. 660 L of corn soaking water in batch 3 was filtered through a microfiltration membrane with a pore size of 0.5-1 um to obtain 650 L of supernatant;

[0071] S2. The supernatant was adsorbed with 65 L of macroporous weak basic resin (model D-301) (feed rate of 1 BV / h) to obtain 620 L of effluent;

[0072] S3. 62.5 L of potassium hydroxide solution (mass concentration of 40%) was added to the effluent to adjust the pH to 13, and 80 um centrifuge was used to filter to obtain 34.4 kg of filter cake containing crude protein and calcium and magnesium salts, and 672 L of treated solution;

[0073] S4. The treated solution was treated by a nanofiltration membrane with a molecular weight cut-off of 550 Da to obtain 140 L of second retentate and 532 L of treated solution treated by a nanofiltration membrane;

[0074] S5. The treated solution treated by a nanofiltration membrane was subjected to a reverse osmosis membrane with a molecular weight cut-off of 100 Da to obtain 260 L of first retentate and 272 L of permeate;

[0075] S6. The first retentate was heated at 140 °C and 0.2 MPa for 2 h, and then cooled to 98 °C at normal pressure, and 25% hydrochloric acid was added to adjust the pH to 2.5, and then vacuum concentrated (vacuum degree -0.09 MPa, temperature 70 °C) until crystals precipitated in the solution to obtain 90 L of concentrated solution;

[0076] S7. The concentrated solution was cooled at a rate of 10 °C / h, and after the temperature dropped to 30 °C, 80 um centrifuge was used to filter to obtain 18.8 kg of KCl crude product (dried, purity 98wt%) and 75 L of the first filtrate;

[0077] S8. Distill the first filtrate under the conditions of -0.095 Mpa vacuum degree and 70°C to remove part of water, then distill under the conditions of absolute pressure 150 Pa and 100°C, and collect the distillate under the conditions of 83°C / 100 Pa to obtain 25 L lactic acid solution (mass concentration 45%) and 21.1 kg distillation dry matter.

[0078] Example 6

[0079] S1. Heat the 120 L second retentate obtained in step S4 of Example 3 under the conditions of 130°C and 0.25 Mpa for 1 h, and cool to 95°C under normal pressure;

[0080] S2. Add concentrated hydrochloric acid to adjust the pH to neutral, and transfer into spray drying (inlet air temperature 130°C, outlet air temperature 95°C) treatment to obtain 36 kg corn protein powder.

[0081] Example 7

[0082] S1. Heat the 120 L second retentate obtained in step S4 of Example 4 under the conditions of 120°C and 0.3 Mpa for 0.5 h, and cool to 90°C under normal pressure;

[0083] S2. Add concentrated hydrochloric acid to adjust the pH to neutral, and transfer into spray drying (inlet air temperature 120°C, outlet air temperature 100°C) treatment to obtain 35.8 kg corn protein powder.

[0084] Example 8

[0085] S1. Heat the 120 L second retentate obtained in step S4 of Example 5 under the conditions of 140°C and 0.2 Mpa for 2 h, and cool to 98°C under normal pressure;

[0086] S2. Add concentrated hydrochloric acid to adjust the pH to neutral, and transfer into spray drying (inlet air temperature 140°C, outlet air temperature 90°C) treatment to obtain 35.8 kg corn protein powder.

[0087] Example 9

[0088] S1. Dissolve the distillation dry matter in Example 3 in purified water, add 400 g activated carbon, filter to obtain 66 L decolorized liquid, vacuum concentrate to obtain a solid content of 50%, and spray dry (inlet air temperature 130°C, outlet air temperature 95°C) to obtain 15 kg small peptide protein powder.

[0089] Example 10

[0090] S1. Dissolve the distillation dry matter in Example 4 in purified water, add 390 g activated carbon, filter to obtain 67 L decolorized liquid, vacuum concentrate to obtain 40 L small peptide solution with a solid content of 50%.

[0091] Example 11

[0092] S1. The distillate dry solids in Example 5 were dissolved in purified water, 400 g of activated carbon was added, and after filtration, 68 L of decolorized solution was obtained, which was concentrated under vacuum to obtain 41 L of small peptide solution with a solid content of 50%.

[0093] Comparative Example 1

[0094] In Example 3, step S3, "adding solid potassium hydroxide to the effluent to adjust the pH to 12.3" was adjusted to (adding solid potassium hydroxide to the effluent to adjust the pH to 11), and other conditions remained unchanged.

[0095] The results showed that 15.4 kg of KCl crude product (dry, purity 82wt%), 20 L of lactic acid solution (mass concentration 48%) and 20.0 kg of distillate dry solids were obtained.

[0096] The results in Comparative Example 1 showed that after the pH adjusted by solid potassium hydroxide was reduced, the amount of KCl crude product was significantly reduced, the concentration of lactic acid solution and the weight of distillate dry solids were slightly reduced. This was because the reduction of pH corresponded to the reduction of potassium hydroxide addition amount, which mainly affected the yield of KCl crude product, because the amount of potassium ions as raw material was reduced, and also partially affected the concentration of lactic acid solution and the weight of distillate dry solids, because the removal rate of impurity ions such as calcium and magnesium was reduced after the addition amount of potassium hydroxide was reduced (calcium and magnesium ions precipitated more obviously at pH 12-13), and the impurity removal effect affected the subsequent separation of lactic acid and distillate dry solids.

[0097] Comparative Example 2

[0098] In Example 4, step S6, "adding hydrochloric acid with a mass concentration of 40% to adjust the pH to 2.0" was adjusted to "adding hydrochloric acid with a mass concentration of 40% to adjust the pH to 3.0", and other conditions remained unchanged.

[0099] The results showed that 17.4 kg of KCl crude product (dry, purity 90wt%), 20 L of lactic acid solution (mass concentration 50%) and 22.6 kg of distillate dry solids were obtained.

[0100] The results of Comparative Example 2 show that reducing the amount of hydrochloric acid added increases the pH value, and the yield of KCl crude product decreases, the lactic acid solution remains basically unchanged (the total amount increases slightly but the concentration decreases slightly), and the amount of distilled dry matter increases. This is because the solution containing potassium chloride is not a pure potassium chloride solution, but also contains other impurity ions. During the crystallization of the potassium chloride solution containing multiple ions, a certain pH needs to be controlled to ensure the stability of potassium chloride and reduce the influence of other ions on the precipitation of potassium chloride. After increasing the pH in Comparative Example 2, potassium chloride cannot remain in a relatively stable state, and potassium ions and chloride ions exist in the form of other compounds, so they cannot be precipitated by crystallization and remain in the solution. This is the reason why the amount of distilled dry matter increases in Comparative Example 2.

[0101] Test Example

[0102] A. The purity of KCl was determined in accordance with the national standard GB / T 13885-2017;

[0103] B. The concentration of the lactic acid solution was determined in accordance with the national standard GB 5009.157-2016.

[0104] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for extracting the active ingredients from corn soaked in water, characterized in that, The method comprises the following steps: corn soaking water is passed through anion exchange resin to adsorb phytic acid, and an effluent is obtained; potassium hydroxide is added to the effluent to adjust the pH to 12-13, and a second filtration is performed to obtain a filter cake containing crude protein and calcium and magnesium salts and a treatment liquid; the treatment liquid is passed through a reverse osmosis membrane with a molecular weight cut-off of 50-100 Da to obtain a first cut-off liquid and a permeate; the first cut-off liquid is kept at 120-140℃ and 0.2-0.3 MPa for 0.5-2 h, is cooled to below 100℃ at normal pressure, hydrochloric acid is added to adjust the pH to 2.0-2.5, and vacuum concentration is performed until crystals are precipitated in the solution to obtain a concentrated liquid; the concentrated liquid is cooled to 30℃ for crystallization, and after crystallization is completed, a first filtration is performed to obtain a KCl crude product and a first filtrate; the first filtrate is distilled, and a fraction under the condition of 82-85℃ / 100 Pa is collected to obtain a lactic acid solution and a distillation dry substance.

2. The method of claim 1, wherein, After the effluent is treated by removing corn protein and removing calcium and magnesium salts to obtain a treatment liquid, before the treatment liquid is passed through a reverse osmosis membrane with a molecular weight cut-off of 50-100 Da, the method further comprises: the treatment liquid is treated by a nanofiltration membrane with a molecular weight cut-off of 450-550 Da to obtain a second cut-off liquid containing corn protein and a treatment liquid treated by the nanofiltration membrane.

3. The method of claim 1, wherein, the mass concentration of the hydrochloric acid is 25-40%; and / or, the vacuum degree of the vacuum concentration is -0.07 MPa to -0.09 MPa, and the temperature is 60-70℃.

4. The method of claim 1, wherein, the crystallization is cooling crystallization, and the cooling rate is 5-10℃ / h; and / or, the first filtration is performed by using a centrifuge, and the filtration pore size is 20-80 um.

5. The method of claim 1, wherein, the first filtrate is distilled, and a fraction under the condition of 82-85℃ / 100 Pa is collected to obtain a lactic acid solution and a distillation dry substance, which comprises: the first filtrate is distilled under the condition of a vacuum degree of -0.09 MPa to -0.095 MPa and a temperature of 60-70℃ to distill part of water, and then is distilled under the condition of an absolute pressure of 50-150 Pa and a temperature of 90-100℃, and a lactic acid solution and a distillation dry substance obtained under the condition of 82-85℃ / 100 Pa are collected.

6. The method according to claim 1 or 5, characterized in that, after the distillation dry substance is obtained, the method further comprises: the distillation dry substance is dissolved in water, the solution is decolorized by activated carbon, a third filtration is performed to obtain a decolorized liquid, and the decolorized liquid is concentrated to obtain a small peptide concentrated liquid with a solid content of 30-35%.

7. The method of claim 1, wherein, after the first filtrate is obtained, before the first filtrate is distilled, the method further comprises: the first filtrate is adsorbed by a strong acid cation resin; the adsorbed resin is eluted with 15-40 wt% hydrochloric acid to obtain an elution liquid; the elution liquid is mixed with the first cut-off liquid, and subsequent steps are continued.

8. The method of claim 2, wherein, after the second cut-off liquid is obtained, the method further comprises: the second cut-off liquid is kept at 120-140℃ and 0.2-0.3 MPa for 0.5-2 h; concentrated hydrochloric acid is added to the reaction liquid to adjust the pH to neutral; spray drying is performed to obtain corn protein powder.

9. The method of claim 1, wherein, before the corn soaking water is passed through anion exchange resin to adsorb phytic acid, the method further comprises: the corn soaking water is pretreated to remove impurities; The pretreatment includes standing at 45-50 DEG C, using a hydrocyclone or using a microfiltration membrane to remove impurities. The pretreatment includes standing at 45-50 DEG C, using a hydrocyclone or using a microfiltration membrane to remove impurities. The pretreatment includes