A method for producing inositol and by-products using corn steep liquor at low cost

Abstract

The invention discloses a method for producing inositol and byproducts with low cost by using corn slurry: the supernatant after the initial precipitation of corn slurry is pumped into an anion exchange resin column for sequential adsorption and desorption, and the desorption liquid is collected; the desorption liquid is concentrated by membrane to obtain phytic acid concentrated liquid; the phytic acid concentrated liquid is sequentially hydrolyzed and filtered, and the filtrate is concentrated and separated by chromatography to obtain an inositol phase and a salt phase; the salt phase is sequentially concentrated by ceramic membrane and nanofiltration membrane, the concentrated liquid is filtered after cooling and crystallization, and the byproduct potassium dihydrogen phosphate is obtained after precipitation and drying; the inositol phase is sequentially concentrated by ceramic membrane and nanofiltration membrane, the concentrated liquid is filtered after cooling and crystallization, and the precipitation and drying is inositol. The above process removes the four-effect and six-effect and MVR concentration processes, saves a large amount of steam consumption, and also reduces the emission of waste gas and the consumption of cooling water in the cooling water tower, greatly reducing the production cost of inositol and byproducts.

Description

Technical Field

[0001] The invention relates to the technical field of inositol production, and in particular to a method for producing inositol and byproducts at low cost by utilizing corn steep liquor. Background Art

[0002] At present, the production method of inositol is to pass corn soaking water through a weakly basic anion resin column, desorb the phytic acid adsorbed on the resin with potassium chloride, and obtain a mixture of potassium phytate and excess potassium chloride. The desorbed liquid enters a hydrolysis tank after membrane concentration for hydrolysis and filtration to obtain a mixed solution of inositol and potassium dihydrogen phosphate, and then obtains two solutions of inositol and potassium dihydrogen phosphate after chromatographic separation, but the concentrations of the two solutions are relatively low. The existing process is to crystallize after MVR-four-effect double concentration to obtain pure inositol and potassium dihydrogen phosphate. The above process needs to consume a large amount of steam and needs to be carried out under vacuum conditions, the equipment consumes a lot of energy, and the operation is relatively complicated.

[0003] In addition, the following problems also exist in the production of inositol: 1. A large amount of washing water is consumed during the hydrolysis and filtration of the desorption liquid. Concentrating the washing water and the filtrate together will greatly increase the energy consumption during concentration, thereby increasing the production cost of inositol; 2. The potassium dihydrogen phosphate solution contains a certain amount of potassium chloride, which will reduce the concentration of the by-product potassium dihydrogen phosphate if it is not treated; 3. The large amount of wastewater generated in the production of inositol cannot be effectively utilized, increasing the production cost of inositol. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the shortcomings of the prior art, a method for producing inositol and by-products from corn slurry at low cost is provided. The method comprises the following steps: the corn slurry is initially precipitated and then subjected to resin column adsorption treatment, followed by desorption, and the desorbed liquid is initially concentrated and then hydrolyzed, thereby preliminarily increasing the concentration of phytic acid and by-products in the hydrolyzed liquid; the hydrolyzed liquid is filtered and then subjected to membrane concentration and chromatographic separation, thereby further increasing the concentration of phytic acid and by-products; the salt phase and inositol phase after chromatographic separation are respectively filtered through ceramic membranes and nanofiltration membranes and then crystallized; the process eliminates the four-effect and six-effect and MVR concentration processes, thereby saving a large amount of steam consumption, while also reducing the emission of waste gas and the consumption of cooling water in a cooling water tower, thereby greatly reducing the production cost of inositol and by-products.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A method for producing inositol and byproducts at low cost by using corn steep liquor comprises the following steps:

[0007] (1) pumping the supernatant after the initial precipitation of the corn steep liquor into an anion exchange resin column for adsorption treatment, then performing desorption treatment with a desorbent, and collecting the desorbed liquid;

[0008] (2) performing a preliminary concentration treatment on the desorption liquid using a membrane, collecting the permeate and the phytic acid concentrate; performing a high temperature and high pressure hydrolysis treatment on the phytic acid concentrate, filtering the hydrolyzate, and collecting the filtrate;

[0009] (3) performing membrane concentration on the filtrate collected in step (2) and collecting the concentrate and the permeate; performing chromatographic separation on the concentrate to obtain an inositol phase and a salt phase;

[0010] (4) The salt phase collected in step (3) is concentrated by a ceramic membrane to collect a primary concentrate and a primary permeate, the primary concentrate is concentrated by a nanofiltration membrane to collect a secondary concentrate and a secondary permeate, the secondary concentrate is subjected to a cooling crystallization treatment, and then filtered, the precipitate obtained by filtration is dried to obtain a by-product of potassium dihydrogen phosphate, the mother liquor obtained by filtration is recovered and mixed with the next batch of secondary concentrates for cooling crystallization treatment;

[0011] (5) the inositol phase collected in step (3) is first concentrated by a ceramic membrane, a primary concentrate and a primary permeate are collected, the primary concentrate is concentrated by a nanofiltration membrane, a secondary concentrate and a secondary permeate are collected, the secondary concentrate is subjected to a cooling crystallization treatment, and then filtered, the precipitate obtained by filtration is dried to obtain inositol, the mother liquor obtained by filtration is recovered and mixed with the next batch of secondary concentrates for cooling crystallization treatment;

[0012] (6) The permeate collected in step (3), the primary permeate collected in step (5), and the secondary permeate collected are used to prepare lime water; the permeate collected in step (2), the primary permeate collected in step (4), and the secondary permeate collected are used to prepare a desorbent.

[0013] As a preferred embodiment of the above technical solution, in step (1), during the adsorption treatment, the flow rate of the supernatant is 1.2-1.4 Bv / h, and the volume of the supernatant is 15-16 times the volume of the anion exchange resin.

[0014] As a preferred embodiment of the above technical solution, in step (1), the desorbent is a potassium chloride solution with a mass concentration of 10-15%, the volume of the desorbent is 1-2 times the volume of the anion exchange resin, and the flow rate of the desorbent during desorption is 0.3-0.6 Bv / h.

[0015] As a preferred embodiment of the above technical solution, in step (2), the membrane used in the preliminary concentration treatment is a nanofiltration membrane with a molecular weight cutoff of 500-600, the pressure used in the preliminary concentration treatment is controlled below 4 MPa, and the temperature used in the preliminary concentration treatment is controlled below 55°C.

[0016] As a preferred embodiment of the above technical solution, in step (2), the temperature of the high temperature and high pressure hydrolysis treatment is 160-180°C, the pressure is 0.6-1MPa, and the time is 9-12h.

[0017] As a preferred embodiment of the above technical solution, in step (3), the molecular weight cutoff of the membrane during concentration is 100-150, the pressure during concentration does not exceed 3.5 MPa, and the temperature does not exceed 55°C.

[0018] As a preferred embodiment of the above technical solution, in step (4), the pore size of the ceramic membrane used in ceramic membrane concentration is 40-60nm, and the temperature during concentration does not exceed 80°C; the molecular weight cutoff of the nanofiltration membrane used in nanofiltration membrane concentration is 150-200, the membrane pressure is ≤3.0MPa, and the membrane temperature is ≤50°C.

[0019] As a preferred embodiment of the above technical solution, in step (5), the pore size of the ceramic membrane used in ceramic membrane concentration is 50nm; the molecular weight cutoff of the nanofiltration membrane used in nanofiltration membrane concentration is 100-150, the membrane pressure is ≤4.0MPa, and the membrane temperature is ≤50°C.

[0020] Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0021] The present invention uses corn syrup as raw material, and after initial precipitation, phytic acid is adsorbed by anion exchange resin, and then the resin column is desorbed to obtain a desorption liquid containing phytic acid, and then the desorption liquid is preliminarily concentrated, the concentrated liquid is hydrolyzed and filtered, and the filtrate is concentrated by membrane and then chromatographically separated to obtain an inositol phase and a salt phase; the obtained inositol phase and salt phase are filtered by ceramic membrane and nanofiltration membrane respectively and then crystallized. In the above method, the four-effect and six-effect and MVR concentration processes are removed, a large amount of steam consumption is saved, and the emission of waste gas and the consumption of cooling water towers are also reduced. Moreover, the inositol concentration after concentration can reach 20%-30%, and potassium dihydrogen phosphate can also remove part of the residual potassium chloride during the membrane concentration process, thereby improving the purity of potassium dihydrogen phosphate. In addition, the permeate during the concentration in the above method can be used for the preparation of lime water or the preparation of a desorbent, realizing the recycling of water resources, reducing the production cost of inositol and by-products, and also reducing the input amount of the desorbent potassium chloride solution, and the above process is safe and environmentally friendly, and no waste and pollutants are generated. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0023] Example 1

[0024] (1) performing a preliminary sedimentation treatment on the corn syrup, and pumping the supernatant after the sedimentation into an anion exchange resin column in a countercurrent manner for phytic acid adsorption treatment, wherein the flow rate of the supernatant is controlled to be 1.2 Bv / h during the adsorption treatment, and the volume of the supernatant is 15.5 times the volume of the anion exchange resin, and then performing a desorption treatment using a potassium chloride solution with a mass concentration of 12%, and collecting the desorbed liquid; during the desorption treatment, the volume of the potassium chloride solution is 1.6 times the volume of the anion exchange resin, and the flow rate of the potassium chloride solution is controlled to be 0.5 Bv / h;

[0025] (2) The desorbed liquid is preliminarily concentrated using a nanofiltration membrane with a molecular weight cutoff of 500-600 at a pressure of less than 4 MPa and a temperature of less than 55° C., and the permeate and phytic acid concentrate are collected; the phytic acid concentrate is pumped into a hydrolysis tank, and hydrolyzed for 10.5 h at a temperature of 160° C. and a pressure of 0.7 MPa, and then the hydrolyzate is filtered and the filtrate is collected;

[0026] (3) concentrating the filtrate collected in step (2) using a nanofiltration membrane with a molecular weight cutoff of 100-150 at a concentration pressure not exceeding 3.5 MPa and a temperature not exceeding 55° C., collecting the concentrate and the permeate; and performing chromatographic separation on the concentrate to obtain an inositol phase and a salt phase;

[0027] (4) The salt phase collected in step (3) is first concentrated through a ceramic membrane with a pore size of 50 nm, and a primary permeate and a primary concentrate are collected. The primary concentrate is concentrated through a nanofiltration membrane with a molecular weight cutoff of 150-200 under the conditions of pressure ≤3.0 MPa and temperature ≤50° C., and a secondary concentrate and a secondary permeate are collected. The secondary concentrate is subjected to a cooling crystallization treatment and then filtered. The precipitate obtained by filtration is dried to obtain the by-product potassium dihydrogen phosphate. The mother liquor obtained by filtration is recovered and mixed with the next batch of concentrated liquid for cooling crystallization treatment;

[0028] (5) the inositol phase collected in step (3) is first concentrated by a ceramic membrane with a pore size of 50 nm, and a primary permeate and a primary concentrate are collected. The primary concentrate is concentrated by a nanofiltration membrane with a molecular weight cutoff of 100-150 under the conditions of pressure ≤4.0 MPa and temperature ≤50° C., and a secondary concentrate and a secondary permeate are collected. The secondary concentrate is subjected to a cooling crystallization treatment, and then filtered. The precipitate obtained by filtration is dried to obtain inositol. The mother liquor obtained by filtration is recovered and mixed with the next batch of concentrated liquid for cooling crystallization treatment;

[0029] (6) The permeate collected in step (3), the primary permeate collected in step (5), and the secondary permeate collected are used to prepare lime water; the permeate collected in step (2), the primary permeate collected in step (4), and the secondary permeate collected are used to prepare a desorbent.

[0030] Example 2

[0031] (1) performing a preliminary sedimentation treatment on the corn syrup, and pumping the supernatant after the sedimentation into an anion exchange resin column in a countercurrent manner for phytic acid adsorption treatment, wherein the flow rate of the supernatant is controlled to be 1.3 Bv / h during the adsorption treatment, and the volume of the supernatant is 15.4 times the volume of the anion exchange resin, and then performing a desorption treatment using a potassium chloride solution with a mass concentration of 12%, and collecting the desorbed liquid; during the desorption treatment, the volume of the potassium chloride solution is 1.7 times the volume of the anion exchange resin, and the flow rate of the potassium chloride solution is controlled to be 0.5 Bv / h;

[0032] (2) The desorbed liquid is preliminarily concentrated using a nanofiltration membrane with a molecular weight cutoff of 500-600 at a pressure of less than 4 MPa and a temperature of less than 55° C., and the permeate and phytic acid concentrate are collected; the phytic acid concentrate is pumped into a hydrolysis tank, and hydrolyzed for 10.5 h at a temperature of 165° C. and a pressure of 0.75 MPa, and then the hydrolyzate is filtered and the filtrate is collected;

[0033] (3) concentrating the filtrate collected in step (2) using a nanofiltration membrane with a molecular weight cutoff of 100-150 at a concentration pressure not exceeding 3.5 MPa and a temperature not exceeding 55° C., collecting the concentrate and the permeate; and performing chromatographic separation on the concentrate to obtain an inositol phase and a salt phase;

[0034] (4) The salt phase collected in step (3) is first concentrated through a ceramic membrane with a pore size of 50 nm, and a primary permeate and a primary concentrate are collected. The primary concentrate is concentrated through a nanofiltration membrane with a molecular weight cutoff of 150-200 under the conditions of pressure ≤3.0 MPa and temperature ≤50° C., and a secondary concentrate and a secondary permeate are collected. The secondary concentrate is subjected to a cooling crystallization treatment and then filtered. The precipitate obtained by filtration is dried to obtain the by-product potassium dihydrogen phosphate. The mother liquor obtained by filtration is recovered and mixed with the next batch of concentrated liquid for cooling crystallization treatment;

[0035] (5) the inositol phase collected in step (3) is first concentrated by a ceramic membrane with a pore size of 50 nm, and a primary permeate and a primary concentrate are collected. The primary concentrate is concentrated by a nanofiltration membrane with a molecular weight cutoff of 100-150 under the conditions of pressure ≤4.0 MPa and temperature ≤50° C., and a secondary concentrate and a secondary permeate are collected. The secondary concentrate is subjected to a cooling crystallization treatment, and then filtered. The precipitate obtained by filtration is dried to obtain inositol. The mother liquor obtained by filtration is recovered and mixed with the next batch of concentrated liquid for cooling crystallization treatment;

[0036] (6) The permeate collected in step (3), the primary permeate collected in step (5), and the secondary permeate collected are used to prepare lime water; the permeate collected in step (2), the primary permeate collected in step (4), and the secondary permeate collected are used to prepare a desorbent.

[0037] Example 3

[0038] (1) performing a preliminary sedimentation treatment on the corn syrup, and pumping the supernatant after the sedimentation into an anion exchange resin column in a countercurrent manner for phytic acid adsorption treatment, wherein the flow rate of the supernatant is controlled to be 1.4 Bv / h during the adsorption treatment, and the volume of the supernatant is 15.6 times the volume of the anion exchange resin, and then performing a desorption treatment using a potassium chloride solution with a mass concentration of 12%, and collecting the desorbed liquid; during the desorption treatment, the volume of the potassium chloride solution is 1.6 times the volume of the anion exchange resin, and the flow rate of the potassium chloride solution is controlled to be 0.5 Bv / h;

[0039] (2) The desorbed liquid is preliminarily concentrated using a nanofiltration membrane with a molecular weight cutoff of 500-600 at a pressure of less than 4 MPa and a temperature of less than 55° C., and the permeate and phytic acid concentrate are collected; the phytic acid concentrate is pumped into a hydrolysis tank, and hydrolyzed for 10.5 h at a temperature of 170° C. and a pressure of 0.65 MPa, and then the hydrolyzate is filtered and the filtrate is collected;

[0040] (3) concentrating the filtrate collected in step (2) using a nanofiltration membrane with a molecular weight cutoff of 100-150 at a concentration pressure not exceeding 3.5 MPa and a temperature not exceeding 55° C., collecting the concentrate and the permeate; and performing chromatographic separation on the concentrate to obtain an inositol phase and a salt phase;

[0041] (4) The salt phase collected in step (3) is first concentrated through a ceramic membrane with a pore size of 50 nm, and a primary permeate and a primary concentrate are collected. The primary concentrate is concentrated through a nanofiltration membrane with a molecular weight cutoff of 150-200 under the conditions of pressure ≤3.0 MPa and temperature ≤50° C., and a secondary concentrate and a secondary permeate are collected. The secondary concentrate is subjected to a cooling crystallization treatment and then filtered. The precipitate obtained by filtration is dried to obtain the by-product potassium dihydrogen phosphate. The mother liquor obtained by filtration is recovered and mixed with the next batch of concentrated liquid for cooling crystallization treatment;

[0042] (5) the inositol phase collected in step (3) is first concentrated by a ceramic membrane with a pore size of 50 nm, and a primary permeate and a primary concentrate are collected. The primary concentrate is concentrated by a nanofiltration membrane with a molecular weight cutoff of 100-150 under the conditions of pressure ≤4.0 MPa and temperature ≤50° C., and a secondary concentrate and a secondary permeate are collected. The secondary concentrate is subjected to a cooling crystallization treatment, and then filtered. The precipitate obtained by filtration is dried to obtain inositol. The mother liquor obtained by filtration is recovered and mixed with the next batch of concentrated liquid for cooling crystallization treatment;

[0043] (6) The permeate collected in step (3), the primary permeate collected in step (5), and the secondary permeate collected are used to prepare lime water; the permeate collected in step (2), the primary permeate collected in step (4), and the secondary permeate collected are used to prepare a desorbent.

[0044] Example 4

[0045] (1) performing a preliminary sedimentation treatment on the corn syrup, and pumping the supernatant after the sedimentation into an anion exchange resin column in a countercurrent manner for phytic acid adsorption treatment, wherein the flow rate of the supernatant is controlled to be 1.3 Bv / h during the adsorption treatment, and the volume of the supernatant is 15.6 times the volume of the anion exchange resin, and then performing a desorption treatment using a potassium chloride solution with a mass concentration of 12%, and collecting the desorbed liquid; during the desorption treatment, the volume of the potassium chloride solution is 1.7 times the volume of the anion exchange resin, and the flow rate of the potassium chloride solution is controlled to be 0.5 Bv / h;

[0046] (2) The desorbed liquid is preliminarily concentrated using a nanofiltration membrane with a molecular weight cutoff of 500-600 at a pressure of less than 4 MPa and a temperature of less than 55° C., and the permeate and phytic acid concentrate are collected; the phytic acid concentrate is pumped into a hydrolysis tank, and hydrolyzed for 10.5 h at a temperature of 180° C. and a pressure of 0.8 MPa, and then the hydrolyzate is filtered and the filtrate is collected;

[0047] (3) concentrating the filtrate collected in step (2) using a nanofiltration membrane with a molecular weight cutoff of 100-150 at a concentration pressure not exceeding 3.5 MPa and a temperature not exceeding 55° C., collecting the concentrate and the permeate; and performing chromatographic separation on the concentrate to obtain an inositol phase and a salt phase;

[0048] (4) The salt phase collected in step (3) is first concentrated through a ceramic membrane with a pore size of 50 nm, and a primary permeate and a primary concentrate are collected. The primary concentrate is concentrated through a nanofiltration membrane with a molecular weight cutoff of 150-200 under the conditions of pressure ≤3.0 MPa and temperature ≤50° C., and a secondary concentrate and a secondary permeate are collected. The secondary concentrate is subjected to a cooling crystallization treatment and then filtered. The precipitate obtained by filtration is dried to obtain the by-product potassium dihydrogen phosphate. The mother liquor obtained by filtration is recovered and mixed with the next batch of concentrated liquid for cooling crystallization treatment;

[0049] (5) the inositol phase collected in step (3) is first concentrated by a ceramic membrane with a pore size of 50 nm, and a primary permeate and a primary concentrate are collected. The primary concentrate is concentrated by a nanofiltration membrane with a molecular weight cutoff of 100-150 under the conditions of pressure ≤4.0 MPa and temperature ≤50° C., and a secondary concentrate and a secondary permeate are collected. The secondary concentrate is subjected to a cooling crystallization treatment, and then filtered. The precipitate obtained by filtration is dried to obtain inositol. The mother liquor obtained by filtration is recovered and mixed with the next batch of concentrated liquid for cooling crystallization treatment;

[0050] (6) The permeate collected in step (3), the primary permeate collected in step (5), and the secondary permeate collected are used to prepare lime water; the permeate collected in step (2), the primary permeate collected in step (4), and the secondary permeate collected are used to prepare a desorbent.

[0051] According to the test, in the above embodiment, the inositol concentration in the solution after the inositol phase is concentrated can reach 20%-30%, and the inositol crystallization recovery rate after cooling and crystallization is as high as 51%; the salt phase is separated by membrane so that the removal rate of potassium chloride is as high as 96%, ensuring the high purity of potassium dihydrogen phosphate, and the recovery rate of the by-product potassium dihydrogen phosphate is as high as 55.5%.

[0052] In addition, it should be understood that after reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for producing inositol and by-products at low cost using corn steep liquor, characterized in that: The following steps are involved: (1) pumping the supernatant after the initial precipitation of the corn slurry into an anion exchange resin column for adsorption treatment, then using a desorbent for desorption treatment, and collecting the desorbed liquid; the desorbent is a potassium chloride solution with a mass concentration of 10-15%; (2) performing a preliminary concentration treatment on the desorption liquid using a membrane, collecting the permeate and the phytic acid concentrate; performing a high-temperature and high-pressure hydrolysis treatment on the phytic acid concentrate, filtering the obtained hydrolyzate, and collecting the filtrate; the high-temperature and high-pressure hydrolysis treatment is performed at a temperature of 160-180° C., a pressure of 0.6-1 MPa, and a time of 9-12 h; (3) performing membrane concentration on the filtrate collected in step (2) and collecting the concentrate and the permeate; performing chromatographic separation on the concentrate to obtain an inositol phase and a salt phase; (4) The salt phase collected in step (3) is first concentrated by a ceramic membrane to collect a primary concentrate and a primary permeate, the primary concentrate is concentrated by a nanofiltration membrane to collect a secondary concentrate and a secondary permeate, the secondary concentrate is subjected to a cooling crystallization treatment, and then filtered, the precipitate obtained by filtration is dried to obtain the by-product potassium dihydrogen phosphate, the mother liquor obtained by filtration is recovered and mixed with the next batch of secondary concentrates for cooling crystallization treatment; the pore size of the ceramic membrane used in the ceramic membrane concentration is 40-60nm, and the temperature during concentration does not exceed 80°C; the molecular weight cutoff of the nanofiltration membrane used in the nanofiltration membrane concentration is 150-200, the membrane pressure is ≤3.0MPa, and the membrane temperature is ≤50°C; (5) The inositol phase collected in step (3) is first concentrated by a ceramic membrane, and a primary concentrate and a primary permeate are collected. The primary concentrate is concentrated by a nanofiltration membrane, and a secondary concentrate and a secondary permeate are collected. The secondary concentrate is subjected to a cooling crystallization treatment, and then filtered. The precipitate obtained by filtration is dried to obtain inositol. The mother liquor obtained by filtration is recovered and mixed with the next batch of secondary concentrates for cooling crystallization treatment. The pore size of the ceramic membrane used in the ceramic membrane concentration is 50 nm. The molecular weight cutoff of the nanofiltration membrane used in the nanofiltration membrane concentration is 100-150, the membrane pressure is ≤4.0 MPa, and the membrane temperature is ≤50°C. (6) The permeate collected in step (3), the primary permeate collected in step (5), and the secondary permeate collected are used to prepare lime water; the permeate collected in step (2), the primary permeate collected in step (4), and the secondary permeate collected are used to prepare a desorbent.

2. A method for producing inositol and by-products using corn steep liquor at low cost according to claim 1, characterized in that: In step (1), during the adsorption treatment, the flow rate of the supernatant is 1.2-1.4 Bv / h, and the volume of the supernatant is 15-16 times the volume of the anion exchange resin.

3. A method for producing inositol and by-products at low cost using corn steep liquor according to claim 1, characterized in that: In step (1), the volume of the desorbent is 1-2 times the volume of the anion exchange resin, and the flow rate of the desorbent during desorption is 0.3-0.6 Bv / h.

4. A method for producing inositol and by-products at low cost using corn steep liquor according to claim 1, characterized in that: In step (2), the membrane used in the preliminary concentration treatment is a nanofiltration membrane with a molecular weight cutoff of 500-600, the pressure used in the preliminary concentration treatment is controlled below 4 MPa, and the temperature used in the preliminary concentration treatment is controlled below 55°C.

5. A method for producing inositol and by-products at low cost using corn steep liquor according to claim 1, characterized in that: In step (3), the molecular weight cutoff of the membrane during concentration is 100-150, the pressure during concentration does not exceed 3.5 MPa, and the temperature does not exceed 55°C.