Method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water

Abstract

The invention discloses a method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water. The method comprises the following steps: filtering the phytic acid-removed corn soaking water by adopting a ceramic membrane, and collecting permeate I; adding tartaric acid into the permeate I to adjust pH, cooling for reaction, filtering and collecting filtrate I; concentrating the filtrate I to obtain a concentrated solution I, cooling and crystallizing the concentrated solution I, filtering to obtain filtrate II and a filter cake II, and drying the filter cake II to obtain lactic acid; adding water into the filtrate II for dilution to obtain a diluent, performing electrodialysis treatment on the diluent, and collecting a desalinated solution and a salt phase solution; concentrating the desalinated solution to obtain a concentrated solution II, and drying to obtain protein; concentrating the salt phase liquid to obtain a concentrated solution III, thermally concentrating the concentrated solution III to obtain a concentrated solution IV, decolorizing the concentrated solution IV, filtering, crystallizing the filtrate, filtering to obtain a filtrate III and a filter cake III, and drying the filter cake III to obtain potassium chloride. Effective components in the phytic acid-removed corn soaking water are recovered under certain conditions, the economic value of the phytic acid-removed corn soaking water is improved, the operation is simple, and the cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of corn soaking water, and in particular to a method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water. Background Art

[0002] Corn steep water is a byproduct of corn processing and is rich in phytic acid and inositol. Phytic acid is an organic acid naturally present in plant seeds. It has a strong chelating effect and can form stable complexes with metal ions. Inositol is a water-soluble bioactive substance with multiple physiological functions, such as improving cell metabolism and lowering cholesterol. Therefore, corn steep water is mainly used to produce phytic acid and inositol.

[0003] At present, phytic acid in corn soaking water is mainly adsorbed by resin. In this process, a large amount of dephyticated corn soaking water will be produced. This part of the solution also contains rich effective substances such as water-soluble protein, lactic acid and salts. Therefore, how to recover the above substances from the solution is of great significance.

[0004] The patent with application number 202410688746.X discloses a method for preparing high-content protein and co-producing salt using corn soaking water, specifically: removing phytic acid and filtering corn soaking water, sequentially adsorbing it through acidified ZG-6 resin and alkalized ZG-312 resin, the effluent of alkalized ZG-312 is evaporated and concentrated, cooled and crystallized, centrifuged, and the supernatant is spray-dried to obtain protein powder, and centrifuged and precipitated to obtain lactate; the acidified ZG-6 resin is analyzed by hydrochloric acid solution, and the solvent is removed from the analytical solution to obtain inorganic salts, and the alkalized ZG-312 resin is analyzed by alkali solution, and the solvent is removed from the analytical solution to obtain metal salts. Although the above method recovers the protein, lactate and metal salt in the phytic acid removal solution, the whole process uses a large amount of organic solvents, and the process is complicated, which increases the cost. Summary of the invention

[0005] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, a method for efficiently recovering protein, lactic acid and potassium chloride in dephytic acid corn soaking water is provided. The method recovers the effective ingredients in the dephytic acid corn soaking water under certain conditions, improves the economic value of the dephytic acid corn soaking water, and is simple to operate and low in cost.

[0006] In order to solve the above technical problems, the technical solution of the present invention is:

[0007] A method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water comprises the following steps:

[0008] (1) Using a ceramic membrane to filter the corn soaking water to remove phytic acid, and collecting the permeate;

[0009] (2) adding tartaric acid to the permeate 1 to adjust the pH of the solution to 5-5.5, cooling the solution for reaction, and after the reaction is completed, filtering the feed solution and collecting the filtrate 1;

[0010] (3) concentrating the filtrate 1 to obtain a concentrated solution 1, slowly cooling the concentrated solution 1, performing a crystallization treatment, and finally filtering the crystallization liquid to obtain a filtrate 2 and a filter cake 2, and drying the filter cake 2 to obtain lactic acid;

[0011] (4) adding water to dilute the second filtrate to obtain a dilute solution, subjecting the dilute solution to electrodialysis treatment, using a monovalent and divalent ion separation membrane as the electrodialysis membrane, treating the solution in the desalination chamber until the conductivity is less than 8-9 ms / cm, stopping the operation, and collecting the desalinated solution and the salt phase liquid;

[0012] (5) concentrating the desalinated liquid to obtain concentrated liquid 2, and finally drying to obtain a protein product;

[0013] (6) The salt phase liquid is concentrated by reverse osmosis membrane to obtain concentrated solution 3, concentrated solution 3 is thermally concentrated to obtain concentrated solution 4, concentrated solution 4 is decolorized and filtered while hot, the filtrate is cooled and crystallized, and then the crystallization liquid is filtered to obtain filtrate 3 and filter cake 3, and filter cake 3 is dried to obtain potassium chloride; filtrate 3 is combined with the next batch of salt phase liquid for treatment.

[0014] Preferably, in step (1), the filtration pore size of the ceramic membrane is 40-60 nm.

[0015] Preferably, in step (2), the tartaric acid is 0.5-1% of the volume of the permeate 1; and potassium hydroxide is used to adjust the pH of the permeate 1.

[0016] Preferably, in step (2), the cooling reaction process is to cool the permeate to 20°C at a rate of 10°C / h and react for 2-4h;

[0017] Preferably, in step (3), the solid content of the concentrated solution 1 is 58-63wt%; the slow cooling process is to cool the temperature to 25°C at a cooling rate of 10°C / h, and the crystallization treatment is performed for 12-24h.

[0018] Preferably, in step (4), the refractive index of the diluent is 20-30; during electrodialysis treatment, water is added to the salt phase chamber, and one of potassium sulfate solution and sodium sulfate solution is added to the electrode chamber, and the concentration of the potassium sulfate solution and the sodium sulfate solution is 3-5wt%; the fixed current during electrodialysis treatment is 3.3-3.5A.

[0019] Preferably, in step (5), the solid content of the concentrated solution 2 is 50-55 wt %.

[0020] Preferably, in step (6), the solid content of the concentrated solution three is 13 wt%, and the membrane pressure during concentration is 5-6 MPa; the solid content of the concentrated solution four is 60 wt%.

[0021] Preferably, in step (6), activated carbon is added during the decolorization treatment, the amount of activated carbon added is 1-3‰ of the volume of the concentrated solution, the decolorization temperature is 80°C, and the time is 2-3h.

[0022] Preferably, in step (6), during the cooling crystallization, the filtrate after the decolorization treatment is cooled to 20°C at a rate of 10-15°C / h, and the crystallization treatment is performed for 12-20h.

[0023] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0024] 1. The present invention uses a ceramic membrane to perform preliminary filtration and clarification on the dephytic acid corn soaking water, thereby removing impurities in the dephytic acid corn soaking water and facilitating subsequent treatment.

[0025] 2. The present invention adopts tartaric acid to remove calcium ions and magnesium ions in the solution. By controlling the dosage of tartaric acid, the reaction temperature, the pH value of the solution and other conditions, the calcium ions and magnesium ions in the solution are fully complexed and precipitated with the tartaric acid. On the one hand, the stability of the electrodialysis process is ensured and the separation efficiency is improved. On the other hand, it is also convenient for the subsequent recovery of lactic acid in the solution.

[0026] 3. In order to recover the lactic acid in the solution, the present invention concentrates the solution to a certain solid content before crystallization, and then precipitates the lactic acid by controlling the cooling rate, crystallization temperature and crystallization time of the concentrated solution, thereby obtaining a high-content lactic acid.

[0027] 4. The present invention uses electrodialysis to separate the protein and potassium chloride components in the diluent. The electrodialysis membrane uses a monovalent and divalent ion separation membrane. Under certain conditions, the protein is enriched in the protein solution and the potassium chloride is enriched in the salt phase solution. The protein solution is subsequently concentrated and dried to recover the high-content protein; the salt phase solution is subsequently concentrated and crystallized to recover the high-content potassium chloride product.

[0028] 5. The present invention uses phytic acid-removed corn soaking water as raw material, and effectively recovers lactic acid, protein and potassium chloride in the solution by combining concentration, acid precipitation, electrodialysis and other technologies, thereby improving the economic value of the phytic acid-removed corn soaking water. In addition, the entire process uses less organic solvent, generates less waste liquid, and saves energy and reduces consumption. DETAILED DESCRIPTION

[0029] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0031] In order to solve the problems pointed out in the background technology, the present invention discloses the following technical solutions:

[0032] A method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water comprises the following steps:

[0033] (1) Using a ceramic membrane to filter the corn soaking water to remove phytic acid, and collecting the permeate;

[0034] (2) adding tartaric acid to the permeate 1 to adjust the pH of the solution to 5-5.5, cooling the solution for reaction, and after the reaction is completed, filtering the feed solution and collecting the filtrate 1;

[0035] (3) concentrating the filtrate 1 to obtain a concentrated solution 1, slowly cooling the concentrated solution 1, performing a crystallization treatment, and finally filtering the crystallization liquid to obtain a filtrate 2 and a filter cake 2, and drying the filter cake 2 to obtain lactic acid;

[0036] (4) adding water to dilute the second filtrate to obtain a dilute solution, subjecting the dilute solution to electrodialysis treatment, using a monovalent and divalent ion separation membrane as the electrodialysis membrane, treating the solution in the desalination chamber until the conductivity is less than 8-9 ms / cm, stopping the operation, and collecting the desalinated solution and the salt phase liquid;

[0037] (5) concentrating the desalinated liquid to obtain concentrated liquid 2, and finally drying to obtain a protein product;

[0038] (6) The salt phase liquid is concentrated by reverse osmosis membrane to obtain concentrated solution 3, concentrated solution 3 is thermally concentrated to obtain concentrated solution 4, concentrated solution 4 is decolorized and filtered while hot, the filtrate is cooled and crystallized, and then the crystallization liquid is filtered to obtain filtrate 3 and filter cake 3, and filter cake 3 is dried to obtain potassium chloride; filtrate 3 is combined with the next batch of salt phase liquid for treatment.

[0039] Regarding step (1):

[0040] Impurities in the dephytic acid corn soaking water are effectively removed by ceramic membrane filtration.

[0041] In some embodiments of the present invention, the filtration pore size of the ceramic membrane is 40-60 nm; further, preferably 50 nm.

[0042] Regarding step (2):

[0043] The present invention first uses tartaric acid to remove metal ions in the solution before electrodialysis separation, thereby ensuring the stability of electrodialysis separation and reducing the risk of membrane fouling.

[0044] In some embodiments of the present invention, the tartaric acid is 0.5-1% of the volume of the permeate. Under certain conditions, tartaric acid complexes with calcium ions and magnesium ions in the solution to generate calcium tartrate and magnesium tartrate precipitates.

[0045] When magnesium tartrate is used for precipitation, in addition to the amount of tartaric acid added, the precipitation temperature and pH will also affect the removal effect of calcium ions and magnesium ions. If the pH is too high, part of the protein in the solution will precipitate, thereby reducing the yield of the protein, while if the pH is too low, the solubility of calcium tartrate and magnesium tartrate will increase, so that the precipitation is not thorough, affecting the separation effect of subsequent electrodialysis, thereby reducing the purity of the protein. If the temperature is too high, the protein will denature, and the solubility of calcium tartrate and magnesium tartrate will also increase, so that it cannot be completely precipitated; if the temperature is too low, refrigeration equipment needs to be used to cool down, which increases the cost, and low temperature may not react completely tartrate. Therefore, in order to effectively remove calcium ions and magnesium ions in the solution, the present invention effectively controls the pH of the solution to be 5-5.5, specifically preferably 5, 5.1, 5.2, 5.3, 5.4, 5.5, but not limited thereto; the temperature of the cooling reaction is controlled to be 20°C.

[0046] In some embodiments of the present invention, the cooling reaction process is: cooling the permeate to 20°C at a rate of 10°C / h, and reacting for 2-4h. By effectively controlling the cooling rate and reaction time, the calcium ions and magnesium ions in the solution are fully complexed with tartaric acid and precipitated. If the cooling rate is too low, the precipitation efficiency is affected; if the cooling rate is too high, the reaction will be incomplete, and some calcium ions and magnesium ions cannot be complexed with tartaric acid to form precipitation.

[0047] Regarding step (3):

[0048] In order to recover the lactic acid in the solution, the present invention concentrates the filtrate and then slowly cools it down so that the lactic acid in the solution is fully precipitated.

[0049] In some embodiments of the present invention, the solid content of the concentrate 1 is 58-63wt%. Specifically, the solid content of the concentrate 1 is preferably 58wt%, 59wt%, 60wt%, 61wt%, 62wt%, 63wt%, but not limited thereto. The solid content will affect the purity and yield of the product to a certain extent. If the solid content is too large, part of the protein will precipitate out along with the lactic acid during the subsequent cooling and crystallization, which will not only affect the purity of the lactic acid, but also reduce the yield of the protein; if the solid content is too small, part of the lactic acid will remain in the filtrate during the cooling and crystallization, affecting the purity of the protein.

[0050] In some embodiments of the present invention, the cooling rate of slow cooling crystallization is 10°C / h, the temperature of crystallization treatment is 25°C, and the time of crystallization treatment is 12-24h; specifically, the time of crystallization treatment is preferably 12h, 14h, 16h, 18h, 20h, 22h, 24h, but not limited thereto. In this process, too fast cooling rate will cause partial protein precipitation and lower protein yield, while too slow cooling rate will reduce crystallization efficiency and increase cost.

[0051] Regarding step (4):

[0052] The present invention uses electrodialysis technology to separate potassium ions in the second filtrate. In order to ensure a good separation effect, the conditions of electrodialysis separation need to be reasonably controlled.

[0053] In some embodiments of the present invention, the refractive index of the diluent is 20-30, preferably 20, 22, 24, 26, 28, 30, but not limited thereto. If the refractive index of the diluent is too high, that is, the concentration of the solution is too high, the separation effect is affected, while if the refractive index of the diluent is too low, that is, the concentration of the solution is too low, the processing volume and the processing cost will be increased.

[0054] In some embodiments of the present invention, during electrodialysis treatment, at the initial stage of separation, the diluent is pumped into the desalination chamber of the electrodialysis device, water is added to the salt phase chamber, and potassium sulfate solution or sodium sulfate solution is added to the electrode chamber, wherein the concentration of the potassium sulfate solution and the sodium sulfate solution is 3-5wt%; the fixed current during electrodialysis treatment is 3.3-3.5A.

[0055] During separation, the electrodialysis membrane uses a divalent ion separation membrane, which, under certain conditions, can effectively increase the resistance of the divalent ions, thereby separating the monovalent ions in the dilute solution.

[0056] Regarding step (5):

[0057] In some embodiments of the present invention, the solid content of the concentrated solution 2 is 50-55 wt %.

[0058] Regarding step (6):

[0059] The present invention preliminarily concentrates the salt phase liquid, then uses activated carbon for decolorization treatment, and finally performs crystallization under certain conditions to recover potassium chloride in the salt phase liquid.

[0060] In some embodiments of the present invention, the solid content of the concentrated solution three is 13wt%, and the membrane pressure during concentration is 5-6MPa; the solid content of the concentrated solution four is 60wt%.

[0061] In some embodiments of the present invention, activated carbon is added during the decolorization treatment, the amount of activated carbon added is 1-3‰ of the volume of the concentrated solution, the decolorization temperature is 80°C, and the time is 2-3h.

[0062] In some embodiments of the present invention, during the cooling crystallization, the filtrate after the decolorization treatment is cooled to 20° C. at a rate of 10-15° C. / h, and the crystallization treatment is performed for 12-20 hours.

[0063] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0064] In the following examples, unless otherwise specified, the raw materials are all commercially available and the conditions are all conventional conditions in the art.

[0065] The yield of the target product is calculated as follows:

[0066] Lactic acid (%) = [(mass of lactic acid product × lactic acid content in lactic acid product) / (mass of corn soaking water × lactic acid content in corn soaking water)] × 100%;

[0067] Protein (%) = [(mass of protein product × protein content in protein product) / (mass of corn soaking water × protein content in corn soaking water)] × 100%;

[0068] Potassium chloride (%) = [(mass of potassium chloride product × potassium chloride content in potassium chloride product) / (mass of corn soaking water × potassium chloride content in corn soaking water)] × 100%.

[0069] Example 1

[0070] A method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water comprises the following steps:

[0071] (1) 50 kg of phytic acid-free corn soaking water (dry matter 12 wt%, protein content 6 wt%, lactic acid content 3.12 wt%, calcium 50 ppm, magnesium 2000 ppm, potassium chloride 1 wt%) was filtered using a ceramic membrane (filtration pore size 50 nm), and permeate I was collected;

[0072] (2) Add tartaric acid (the amount added is 1% of the volume of the permeate one) to the permeate one, add potassium hydroxide to adjust the pH of the solution to 5, cool to 20°C at a rate of 10°C / h, react for 4h, and after the reaction is completed, filter the feed liquid and collect the filtrate one;

[0073] (3) Concentrating the filtrate 1 to a solid content of 58 wt % to obtain a concentrated solution 1, cooling the concentrated solution 1 to 25 ° C. at a cooling rate of 10 ° C. / h, and performing a crystallization treatment for 18 h. Finally, filtering the crystallization liquid to obtain a filtrate 2 and a filter cake 2, and drying the filter cake 2 to obtain 1.63 kg of lactic acid, with a lactic acid content of 74.1 wt %, and a yield of 77.4%;

[0074] (4) adding water to dilute the filtrate 2 to obtain a dilute solution (refractive index 20), and subjecting the dilute solution to electrodialysis treatment. The electrodialysis membrane uses a monovalent and divalent ion separation membrane (Shandong Tianwei Membrane Technology Co., Ltd.). 0.5 BV of water of the dilute solution volume is added to the salt phase chamber, and a 3 wt % potassium sulfate solution or sodium sulfate solution is added to the electrode chamber. The treatment is carried out at a fixed current of 3.3 A until the conductivity of the solution in the desalination chamber is less than 8-9 ms / cm, and the operation is stopped to collect the desalinated liquid and the salt phase liquid;

[0075] (5) Concentrating the desalinated liquid to a solid content of 50 wt % to obtain a concentrated solution 2, filtering the concentrated solution 2 with a plate and frame filter to obtain a filtered clear liquid, and drying the filtered clear liquid to obtain 3.44 kg of a protein product with a protein content of 74.1 wt % and a yield of 85.0%;

[0076] (6) The salt phase liquid is concentrated by reverse osmosis membrane (the membrane pressure during concentration is 5-6MPa) to a solid content of 13wt% to obtain concentrated solution 3, and concentrated solution 3 is thermally concentrated to a solid content of 70wt% to obtain concentrated solution 4; activated carbon is added to concentrated solution 4 (the addition amount is 3‰ of the volume of concentrated solution 4), and decolorization treatment is performed at 80°C for 3h. After the decolorization treatment is completed, the filtrate is filtered while hot, and the filtrate is cooled to 20°C at a rate of 10°C / h, and crystallization treatment is performed for 8h. Then, the crystallization liquid is filtered to obtain filtrate 3 and filter cake 3, and filter cake 3 is dried to obtain 0.35kg of potassium chloride with a potassium chloride content of 85.1wt% and a yield of 59.6%; filtrate 3 is combined with the next batch of salt phase liquid for treatment.

[0077] Example 2

[0078] A method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water comprises the following steps:

[0079] (1) 50 kg of phytic acid-free corn soaking water (dry matter 12 wt%, protein content 6 wt%, lactic acid content 3.12 wt%, calcium 50 ppm, magnesium 2000 ppm, potassium chloride 1 wt%) was filtered using a ceramic membrane (filtration pore size 50 nm), and permeate I was collected;

[0080] (2) Add tartaric acid (the amount added is 1% of the volume of the permeate one) to the permeate one, add potassium hydroxide to adjust the pH of the solution to 5, cool to 20°C at a rate of 10°C / h, react for 4h, and after the reaction is completed, filter the feed liquid and collect the filtrate one;

[0081] (3) Concentrating the filtrate 1 to a solid content of 60 wt % to obtain a concentrated solution 1, cooling the concentrated solution 1 to 25° C. at a cooling rate of 10° C. / h, and subjecting the solution to crystallization for 12 h. Finally, filtering the crystallization solution to obtain a filtrate 2 and a filter cake 2, and drying the filter cake 2 to obtain 1.61 kg of lactic acid, with a lactic acid content of 73.2 wt % and a yield of 75.5%;

[0082] (4) adding water to dilute the filtrate 2 to obtain a dilute solution (refractive index of 25), and subjecting the dilute solution to electrodialysis treatment. The electrodialysis membrane adopts a monovalent and divalent ion separation membrane (Shandong Tianwei Membrane Technology Co., Ltd.). 0.5 BV of water of the dilute solution volume is added to the salt phase chamber, and a 4 wt% potassium sulfate solution or sodium sulfate solution is added to the electrode chamber. The treatment is carried out at a fixed current of 3.5 A until the conductivity of the solution in the desalination chamber is less than 8-9 ms / cm, and the operation is stopped to collect the desalinated liquid and the salt phase liquid;

[0083] (5) Concentrating the desalinated liquid to a solid content of 53 wt % to obtain a concentrated solution 2, filtering the concentrated solution 2 with a plate and frame filter to obtain a filtered clear liquid, and drying the filtered clear liquid to obtain 3.42 kg of a protein product with a protein content of 73.3 wt % and a yield of 83.6%;

[0084] (6) The salt phase liquid is concentrated by reverse osmosis membrane (the membrane pressure during concentration is 5-6MPa) to a solid content of 13wt% to obtain concentrated solution 3, and concentrated solution 3 is thermally concentrated to a solid content of 65wt% to obtain concentrated solution 4; activated carbon is added to concentrated solution 4 (the addition amount is 2‰ of the volume of concentrated solution 4), and decolorization treatment is performed at 80°C for 3h. After the decolorization treatment is completed, the filtrate is filtered while hot, and the filtrate is cooled to 20°C at a rate of 15°C / h, and crystallization treatment is performed for 10h. Then, the crystallization liquid is filtered to obtain filtrate 3 and filter cake 3, and filter cake 3 is dried to obtain 0.34kg of potassium chloride, with a potassium chloride content of 82.3wt% and a yield of 56.0%; filtrate 3 is combined with the next batch of salt phase liquid for treatment.

[0085] Example 3

[0086] A method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water comprises the following steps:

[0087] (1) 50 kg of phytic acid-free corn soaking water (dry matter 12 wt%, protein content 6 wt%, lactic acid content 3.12 wt%, calcium 50 ppm, magnesium 2000 ppm, potassium chloride 1 wt%) was filtered using a ceramic membrane (filtration pore size 50 nm), and permeate I was collected;

[0088] (2) Add tartaric acid (the amount added is 0.5% of the volume of the permeate 1) to the permeate 1, add potassium hydroxide to adjust the pH of the solution to 5.5, cool to 20°C at a rate of 10°C / h, react for 2h, and after the reaction is completed, filter the feed liquid and collect the filtrate 1;

[0089] (3) Concentrating the filtrate 1 to a solid content of 63 wt % to obtain a concentrated solution 1, cooling the concentrated solution 1 to 25 ° C at a cooling rate of 10 ° C / h, and crystallizing for 18 h. Finally, the crystallization liquid was filtered to obtain a filtrate 2 and a filter cake 2. The filter cake 2 was dried to obtain 1.59 kg of lactic acid, with a lactic acid content of 71.8 wt %, and a yield of 73.2%;

[0090] (4) adding water to dilute the filtrate 2 to obtain a dilute solution (refractive index 30), and subjecting the dilute solution to electrodialysis treatment. The electrodialysis membrane uses a monovalent and divalent ion separation membrane (Shandong Tianwei Membrane Technology Co., Ltd.). 0.5 BV of water of the dilute solution volume is added to the salt phase chamber, and a 5 wt% potassium sulfate solution or sodium sulfate solution is added to the electrode chamber. The treatment is carried out at a fixed current of 3.3 A until the conductivity of the solution in the desalination chamber is less than 8-9 ms / cm. The operation is stopped, and the desalinated liquid and the salt phase liquid are collected;

[0091] (5) Concentrating the desalinated liquid to a solid content of 55 wt% to obtain a concentrated solution 2, filtering the concentrated solution 2 with a plate and frame filter to obtain a filtered clear liquid, and drying the filtered clear liquid to obtain 3.45 kg of a protein product with a protein content of 72 wt%;

[0092] (6) The salt phase liquid is concentrated by reverse osmosis membrane (the membrane pressure during concentration is 5-6MPa) to a solid content of 13wt% to obtain concentrated solution 3, and concentrated solution 3 is thermally concentrated to a solid content of 60wt% to obtain concentrated solution 4; activated carbon is added to concentrated solution 4 (the addition amount is 1‰ of the volume of concentrated solution 4), and decolorization treatment is performed at 80°C for 2h. After the decolorization treatment is completed, the filtrate is filtered while hot, and the filtrate is cooled to 20°C at a rate of 10°C / h, and crystallization treatment is performed for 12h. Then, the crystallization liquid is filtered to obtain filtrate 3 and filter cake 3, and filter cake 3 is dried to obtain 0.33kg of potassium chloride, with a potassium chloride content of 84wt% and a yield of 55.4%; filtrate 3 is combined with the next batch of salt phase liquid for treatment.

[0093] Example 4

[0094] A method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water comprises the following steps:

[0095] (1) 50 kg of phytic acid-free corn soaking water (dry matter 12 wt%, protein content 6 wt%, lactic acid content 3.12 wt%, calcium 50 ppm, magnesium 2000 ppm, potassium chloride 1 wt%) was filtered using a ceramic membrane (filtration pore size 50 nm), and permeate I was collected;

[0096] (2) Add tartaric acid (the amount added is 0.5% of the volume of the permeate 1) to the permeate 1, add potassium hydroxide to adjust the pH of the solution to 5.5, cool to 20°C at a rate of 10°C / h, react for 2h, and after the reaction is completed, filter the feed liquid and collect the filtrate 1;

[0097] (3) Concentrating the filtrate 1 to a solid content of 58 wt % to obtain a concentrated solution 1, cooling the concentrated solution 1 to 25 ° C at a cooling rate of 10 ° C / h, and crystallizing for 24 h. Finally, filtering the crystallization liquid to obtain a filtrate 2 and a filter cake 2. The filter cake 2 was dried to obtain 1.58 kg of lactic acid, with a lactic acid content of 72.6 wt %, and a yield of 73.5%;

[0098] (4) adding water to dilute the filtrate 2 to obtain a dilute solution (refractive index 20), and subjecting the dilute solution to electrodialysis treatment. The electrodialysis membrane adopts a monovalent and divalent ion separation membrane (Shandong Tianwei Membrane Technology Co., Ltd.). 0.5 BV of water of the dilute solution volume is added to the salt phase chamber, and a 3 wt % potassium sulfate solution or sodium sulfate solution is added to the electrode chamber. The treatment is carried out at a fixed current of 3.5 A until the conductivity of the solution in the desalination chamber is less than 8-9 ms / cm. The operation is stopped, and the desalinated liquid and the salt phase liquid are collected;

[0099] (5) Concentrating the desalinated liquid to a solid content of 50 wt % to obtain a concentrated solution 2, filtering the concentrated solution 2 with a plate and frame filter to obtain a filtered clear liquid, and drying the filtered clear liquid to obtain 3.38 kg of a protein product with a protein content of 73.5 wt % and a yield of 82.8%;

[0100] (6) The salt phase liquid is concentrated by reverse osmosis membrane (the membrane pressure during concentration is 5-6 MPa) to a solid content of 13 wt% to obtain concentrated solution 3, and concentrated solution 3 is thermally concentrated to a solid content of 65 wt% to obtain concentrated solution 4; activated carbon is added to concentrated solution 4 (the addition amount is 3‰ of the volume of concentrated solution 4), and decolorization treatment is performed at 80°C for 2 h. After the decolorization treatment is completed, the filtrate is filtered while hot, and the filtrate is cooled to 20°C at a rate of 15°C / h, and crystallization treatment is performed for 14 h. Then, the crystallization liquid is filtered to obtain filtrate 3 and filter cake 3, and filter cake 3 is dried to obtain 0.34 kg of potassium chloride with a potassium chloride content of 83.5 wt% and a yield of 56.8%; filtrate 3 is combined with the next batch of salt phase liquid for treatment.

[0101] In order to verify the effect of the present invention, the following is further described with reference to Example 4 and in combination with a plurality of comparative examples.

[0102] Comparative Example 1

[0103] Compared with Example 1, the difference is that: in step (2), potassium hydroxide is added to adjust the solution pH to 4, and other conditions are the same as in Example 1; 1.38 kg of lactic acid is obtained, the lactic acid content is 68 wt%, and the yield is 60.2%; 3.2 kg of protein product is obtained, the protein content is 68 wt%, and the yield is 72.5 wt%; 0.34 kg of potassium chloride is obtained, the potassium chloride content is 78 wt%, and the yield is 53.0%.

[0104] Comparative Example 2

[0105] Compared with Example 1, the difference is that: in step (2), potassium hydroxide is added to adjust the pH value of the solution to 6.5, and the other conditions are the same as those in Example 1; 1.73 kg of lactic acid is obtained, the lactic acid content is 65.2 wt%, and the yield is 72.3%; 2.98 kg of protein product is obtained, the protein content is 72 wt%, and the yield is 71.5%; 0.29 kg of potassium chloride is obtained, the potassium chloride content is 73.1 wt%, and the yield is 42.4%.

[0106] Comparative Example 4

[0107] Compared with Example 1, the difference is that: in step (2), the temperature is lowered first and then tartaric acid and potassium hydroxide are added, and other conditions are the same as in Example 1; 1.62 kg of lactic acid is obtained, the lactic acid content is 62 wt%, and the yield is 64.4%; 2.8 kg of protein product is obtained, the protein content is 65.1 wt%, and the yield is 60.8%; 0.23 kg of potassium chloride is obtained, the potassium chloride content is 76.2 wt%, and the yield is 35.1%.

[0108] Comparative Example 5

[0109] Compared with Example 1, the difference is that in step (3), the solid content of the concentrated solution 1 is 50wt%, and the other conditions are the same as those in Example 1; 0.9kg of lactic acid is obtained, the lactic acid content is 73.2wt%, and the yield is 42.2%; 3.62kg of protein product is obtained, the protein content is 62wt%, and the yield is 74.8%; 0.32kg of potassium chloride is obtained, the potassium chloride content is 78.8wt%, and the yield is 50.4%.

[0110] Comparative Example 6

[0111] Compared with Example 1, the difference is that: in step (3), the solid content of the concentrated solution 1 is 70wt%, and the other conditions are the same as those in Example 1; 2.1kg of lactic acid is obtained, the lactic acid content is 61wt%, and the yield is 82.1%; 2.66kg of protein product is obtained, the protein content is 69.2wt%, and the yield is 61.4%; 0.33kg of potassium chloride is obtained, the potassium chloride content is 76wt%, and the yield is 50.2%.

[0112] Comparative Example 7

[0113] Compared with Example 1, the difference is that: in step (3), the cooling rate is 20°C / h, and the other conditions are the same as those in Example 1; 1.65kg of lactic acid is obtained, the lactic acid content is 68wt%, and the yield is 71.9%; 3.1kg of protein product is obtained, the protein content is 69.1wt%, and the yield is 71.4%; 0.33kg of potassium chloride is obtained, the potassium chloride content is 80wt%, and the yield is 52.8%.

[0114] Comparative Example 8

[0115] Compared with Example 1, the difference is that: in step (4), the refractive index of the diluent is 40, and the other conditions are the same as those in Example 1; 1.59 kg of lactic acid is obtained, the lactic acid content is 73.2 wt%, and the yield is 74.6%; 3.1 kg of protein product is obtained, the protein content is 62 wt%, and the yield is 64.1%; 0.21 kg of potassium chloride is obtained, the potassium chloride content is 72 wt%, and the yield is 30.2%.

[0116] Comparative Example 9

[0117] Compared with Example 1, the difference is that: in step (4), the fixed current is 2.0A, and the other conditions are the same as those in Example 1; 1.58kg of lactic acid is obtained, the lactic acid content is 72.9wt%, and the yield is 73.8%; 2.9kg of protein product is obtained, the protein content is 67wt%, and the yield is 64.8%; 0.1kg of potassium chloride is obtained, the potassium chloride content is 68wt%, and the yield is 13.6%.

[0118] Comparative Example 10

[0119] Compared with Example 1, the difference is that in step (4), the fixed current is 4.5A, and the other conditions are the same as those in Example 1; 1.64kg of lactic acid is obtained, the lactic acid content is 73.3wt%, and the yield is 77.1%; 2.94kg of protein product is obtained, the protein content is 68wt%, and the yield is 66.6%; 0.12kg of potassium chloride is obtained, the potassium chloride content is 71wt%, and the yield is 17.0%.

[0120] Comparative Example 11

[0121] Compared with Example 1, the difference is that: in step (6), the solid content of the concentrated solution four is 50wt%, and the other conditions are the same as in Example 1; 1.53kg of lactic acid is obtained, the lactic acid content is 72.8wt%, and the yield is 71.4%; 3.4kg of protein product is obtained, the protein content is 72.1wt%, and the yield is 81.7%; 0.09kg of potassium chloride is obtained, the potassium chloride content is 81.2wt%, and the yield is 14.6%.

[0122] In summary, compared with the comparative example, the present invention removes calcium ions and magnesium ions in the dephytic acid solution under certain conditions, and then performs crystallization treatment under certain conditions to recover lactic acid; uses electrodialysis separation treatment to separate potassium chloride and protein in the solution, and finally recovers protein and potassium chloride under certain conditions.

[0123] Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core ideas, including the best mode, and also enable any technician in the field to practice the present invention, including making and using any device or system, and implementing any combined method. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention. The scope of patent protection of the present invention is defined by the claims and may include other embodiments that can be thought of by those skilled in the art. If these other embodiments have structural elements similar to the literal expression of the claims, or if they include equivalent structural elements that are not substantially different from the literal expression of the claims, then these other embodiments should also be included in the scope of the claims.

Claims

1. A method for efficiently recovering protein, lactic acid and potassium chloride from phytic acid-removed corn soaking water, characterized in that: The following steps are involved: (1) Using a ceramic membrane to filter the corn soaking water to remove phytic acid, and collecting the permeate; (2) adding tartaric acid to the permeate 1 to adjust the pH of the solution to 5-5.5, cooling the solution for reaction, and after the reaction is completed, filtering the feed solution and collecting the filtrate 1; (3) concentrating the filtrate 1 to obtain a concentrated solution 1, slowly cooling the concentrated solution 1, performing a crystallization treatment, and finally filtering the crystallization liquid to obtain a filtrate 2 and a filter cake 2, and drying the filter cake 2 to obtain lactic acid; (4) adding water to dilute the second filtrate to obtain a dilute solution, subjecting the dilute solution to electrodialysis treatment, using a monovalent and divalent ion separation membrane as the electrodialysis membrane, treating the solution in the desalination chamber until the conductivity is less than 8-9 ms / cm, stopping the operation, and collecting the desalinated solution and the salt phase liquid; (5) concentrating the desalinated liquid to obtain concentrated liquid 2, and finally drying to obtain a protein product; (6) The salt phase liquid is concentrated by reverse osmosis membrane to obtain concentrated solution 3, concentrated solution 3 is thermally concentrated to obtain concentrated solution 4, concentrated solution 4 is decolorized and filtered while hot, the filtrate is cooled and crystallized, and then the crystallization liquid is filtered to obtain filtrate 3 and filter cake 3, and filter cake 3 is dried to obtain potassium chloride; filtrate 3 is combined with the next batch of salt phase liquid for treatment.

2. A method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water according to claim 1, characterized in that: In step (1), the filtration pore size of the ceramic membrane is 40-60 nm.

3. The method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water according to claim 1, characterized in that: In step (2), the tartaric acid is 0.5-1% of the volume of the permeate 1; and potassium hydroxide is used to adjust the pH of the permeate 1.

4. The method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water according to claim 1, characterized in that: In step (2), the cooling reaction process is to cool the permeate to 20°C at a rate of 10°C / h and react for 2-4h.

5. The method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water according to claim 1, characterized in that: In step (3), the solid content of the concentrated solution 1 is 58-63wt%; the slow cooling process is to cool the temperature to 25°C at a cooling rate of 10°C / h, and the crystallization treatment is 12-24h.

6. The method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water according to claim 1, characterized in that: In step (4), the refractive index of the diluent is 20-30; during the electrodialysis treatment, water is added to the salt phase chamber, and one of potassium sulfate solution and sodium sulfate solution is added to the electrode chamber, and the concentration of the potassium sulfate solution and the sodium sulfate solution is 3-5wt%; the fixed current during the electrodialysis treatment is 3.3-3.5A.

7. The method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water according to claim 1, characterized in that: In step (5), the solid content of the concentrated solution 2 is 50-55wt%.

8. The method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water according to claim 1, characterized in that: In step (6), the solid content of the concentrated solution three is 13wt%, and the membrane pressure during concentration is 5-6MPa; the solid content of the concentrated solution four is 60wt%.

9. The method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water according to claim 1, characterized in that: In step (6), activated carbon is added for decolorization, the amount of activated carbon added is 1-3‰ of the volume of the concentrated solution, the decolorization temperature is 80°C, and the time is 2-3h.

10. The method for efficiently recovering protein, lactic acid and potassium chloride in phytic acid-removed corn soaking water according to claim 1, characterized in that: In step (6), the specific process of cooling crystallization is: cooling the filtrate after decolorization to 20°C at a rate of 10-15°C / h, and crystallizing for 12-20h.