A method and device for pH-controlled separation of mixed monobasic organic acids in fermentation broth

Abstract

The present invention relates to a method and device for separating mixed monobasic organic acids in fermentation liquid by pH control, and belongs to the technical field of organic acid separation. The method comprises introducing fermentation liquid into a desalination chamber; introducing a first electrolyte solution into a buffer chamber connected and symmetrically arranged on both sides of the desalination chamber, and a concentration chamber connected and symmetrically arranged on both sides of the buffer chamber, and regulating the pH of the solution in the buffer chamber by the first electrolyte solution; introducing a second electrolyte solution into a cathode chamber and an anode chamber respectively arranged on both sides of the connected concentration chamber; applying direct current to both ends of the cathode arranged in the cathode chamber and the anode arranged in the anode chamber to complete the separation of mixed monobasic organic acids in the fermentation liquid. The present invention separates mixed monobasic organic acids in the fermentation liquid by pH control electrodialysis technology, and the recovery rate of the monobasic organic acid reaches more than 92%, and the purity can reach more than 99%, which greatly improves the recovery rate and purity of the monobasic organic acid.

Description

Technical Field

[0001] The invention belongs to the technical field of organic acid separation, and in particular relates to a method and a device for separating mixed monobasic organic acids in fermentation liquid by controlling pH. Background Art

[0002] Organic acids are widely used across various industries, often serving as carbon platforms and raw materials for the derivation of various compounds such as alcohols, aldehydes, and esters. Their usage is enormous and continues to grow. With the increasing depletion of non-renewable resources like petroleum and the growing global awareness of environmental pollution prevention and protection, chemical synthesis and other processes for producing organic acids are no longer safe, environmentally friendly, and economical, and are gradually being phased out. Fermentation, which uses raw materials derived from renewable sources, offers advantages such as low cost, mild reaction conditions, and high environmental benefits, making it a promising alternative to traditional methods for producing organic acids.

[0003] Fermentation-based organic acid production is feasible and mature, but the fermentation broth is complex. For example, gluconic acid fermentation broth contains byproducts such as acetic acid and pyruvic acid in addition to gluconic acid; pyruvic acid fermentation broth contains byproducts such as lactic acid and acetic acid; and propionic acid fermentation broth contains byproducts such as acetic acid. Currently, precipitation, extraction, adsorption, and pressure membrane processes are the main methods used to separate mixed monobasic organic acids from fermentation broth. However, these processes have numerous drawbacks. Precipitation, while offering low technical barriers, produces significant amounts of solid pollutants. Extraction-based organic acid separation presents challenges such as similar distribution ratios between organic acids, difficulty separating a single extractant, high extractant consumption, and potential hazards to personnel and the environment. Adsorption methods have low selectivity for single organic acids and require significant amounts of acidic solution to regenerate the ion exchange resin during ion desorption. Furthermore, traditional processes for separating single organic acids from fermentation broths can account for 50-80% of the total cost. Therefore, there is an urgent need for new, pollution-free, and energy-efficient processes for separating mixed monobasic organic acids from fermentation broth. Summary of the Invention

[0004] In response to the above problems, the present invention provides a method and device for separating mixed monobasic organic acids in fermentation broth by pH control. The mixed monobasic organic acids are separated by pH-controlled ion membrane electrodialysis, thereby achieving high-efficiency separation of different monobasic organic acids. In addition, the separation process does not generate solid pollutants, does not consume organic solvents, has high efficiency and low energy consumption.

[0005] The first object of the present invention is to provide a method for controlling the pH of a mixed monobasic organic acid in a fermentation broth, comprising:

[0006] introducing fermentation liquid into the desalination chamber;

[0007] A first electrolyte solution is introduced into the buffer chambers connected and symmetrically arranged on both sides of the desalination chamber, and into the concentrating chambers connected and symmetrically arranged on both sides of the buffer chamber, and the pH of the solution in the buffer chamber is regulated by the first electrolyte solution;

[0008] introducing a second electrolyte solution into the cathode chamber and the anode chamber respectively disposed on both sides of the connected concentrating chamber;

[0009] Direct current is applied to both ends of a cathode disposed in the cathode chamber and an anode disposed in the anode chamber to complete separation of the mixed monobasic organic acid in the fermentation liquid.

[0010] In a specific embodiment of the present invention, the spacer between the desalination chamber and the buffer chamber is an anion exchange membrane and / or a cation exchange membrane; the spacer between the buffer chamber and the concentration chamber is an anion exchange membrane and / or a cation exchange membrane; the spacer between the concentration chamber and the cathode chamber is a sealing membrane; and the spacer between the concentration chamber and the anode chamber is a sealing membrane.

[0011] In a specific embodiment of the present invention, there is at least one desalination chamber.

[0012] In a specific embodiment of the present invention, the number of the buffer chambers is at least 2n, where n is greater than or equal to 1; the 2n buffer chambers are symmetrically distributed with the desalination chamber as the symmetry line, and the buffer chambers located at the distribution boundary are spaced apart from the concentrating chamber.

[0013] In a specific embodiment of the present invention, the fermentation broth is a mixed monobasic organic acid with a concentration of 0.1-2.0 mol / L.

[0014] In a specific embodiment of the present invention, the concentration of the first electrolyte solution is 0.05-1.0 mol / L.

[0015] In a specific embodiment of the present invention, the pH is 0.5-4.0.

[0016] In a specific embodiment of the present invention, the concentration of the second electrolyte solution is 0.1-1.0 mol / L.

[0017] In a specific embodiment of the present invention, the mode of applying direct current is a constant current density, and the current density is 0-50 mA / cm 2 .

[0018] A second object of the present invention is to provide a device for pH control and separation of mixed monobasic organic acids in fermentation broth, comprising a desalination chamber, a buffer chamber connected and symmetrically disposed on both sides of the desalination chamber, a concentrating chamber connected and symmetrically disposed on both sides of the buffer chamber, a cathode chamber and an anode chamber disposed on both sides of the connected concentrating chamber, a cathode disposed in the cathode chamber, and an anode disposed in the anode chamber.

[0019] The desalination chamber is used to introduce fermentation liquid;

[0020] The buffer chamber and the concentrating chamber are used to pass a first electrolyte solution;

[0021] The buffer chamber is also used to control pH;

[0022] The cathode and the anode are configured to be supplied with a direct current.

[0023] Beneficial effects of the present invention:

[0024] The method and device for separating mixed monobasic organic acids in fermentation broth by pH control of the present invention use pH control electrodialysis technology to separate mixed monobasic organic acids in fermentation broth, with a recovery rate of more than 92% and a purity of more than 99%. This greatly improves the recovery rate and purity of the monobasic organic acid and avoids the shortcomings of low efficiency, high energy consumption, and serious environmental pollution in traditional processes for separating monobasic organic acids. The method is economical, green, environmentally friendly, and efficient, and has important industrial application value.

[0025] Other features and advantages of the present invention will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 A flow chart showing a method for controlling pH and separating mixed monobasic organic acids in a fermentation broth according to an embodiment of the present invention is shown;

[0028] Figure 2 One of the devices for controlling pH and separating mixed monobasic organic acids in fermentation broth according to an embodiment of the present invention is shown;

[0029] Figure 3 One of the devices for controlling pH and separating mixed monobasic organic acids in fermentation broth according to an embodiment of the present invention is shown;

[0030] Figure 4 One of the devices for controlling pH and separating mixed monobasic organic acids in fermentation broth according to an embodiment of the present invention is shown;

[0031] Figure 5 A schematic diagram showing changes in the concentration of acetic acid in the buffer chamber 1, and the concentrations of pyruvic acid and acetic acid in the concentrating chamber over time in Example 1 is shown;

[0032] Figure 6 A schematic diagram showing changes in the concentration of acetic acid in buffer chamber 1, the concentration of acetic acid in buffer chamber 2, and the concentrations of pyruvic acid and acetic acid in the concentrating chamber over time in Example 2 is shown;

[0033] Figure 7 A schematic diagram showing changes in the concentration of acetic acid in the buffer chamber 1, and the concentrations of pyruvic acid and acetic acid in the concentrating chamber over time in Example 3 is shown;

[0034] Figure 8 A schematic diagram showing changes in the concentration of acetic acid in the buffer chamber 1 and the concentrations of pyruvic acid and acetic acid in the concentrating chamber over time in Example 4 is shown;

[0035] Figure 9 A schematic diagram showing changes in the concentration of acetic acid in the buffer chamber 1 and the concentrations of pyruvic acid and acetic acid in the concentrating chamber over time in Example 5 is shown;

[0036] Figure 10 A schematic diagram showing changes in the concentration of acetic acid in buffer chamber 1, and the concentrations of pyruvic acid and acetic acid in the concentrating chamber over time in Example 6 is shown;

[0037] Figure 11 Schematic diagram showing the change of formic acid concentration in buffer chamber 1, and pyruvic acid and formic acid concentrations in the concentrating chamber over time in Example 7;

[0038] Figure 12 The graph shows the change over time of the sum of the concentrations of acetic acid and formic acid in the buffer chamber 1 and the sum of the concentrations of pyruvic acid and acetic acid and formic acid in the concentrating chamber in Example 8. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0040] like Figure 1 As shown, a method for controlling pH and separating mixed monobasic organic acids in a fermentation broth according to an embodiment of the present invention comprises:

[0041] Step S1, introducing fermentation liquid into the desalination chamber;

[0042] Step S2, introducing a first electrolyte solution into the buffer chambers connected and symmetrically arranged on both sides of the desalination chamber, and into the concentrating chambers connected and symmetrically arranged on both sides of the buffer chamber, and regulating the pH of the solution in the buffer chamber by the first electrolyte solution;

[0043] Step S3, introducing a second electrolyte solution into the cathode chamber and the anode chamber respectively disposed on both sides of the connected concentrating chamber;

[0044] Step S4: applying direct current to both ends of the cathode disposed in the cathode chamber and the anode disposed in the anode chamber to separate the mixed monobasic organic acid in the fermentation liquid.

[0045] In the above steps, the space between the desalination chamber and the buffer chamber is an anion exchange membrane and / or a cation exchange membrane; the space between the buffer chamber and the concentrating chamber is an anion exchange membrane and / or a cation exchange membrane; the space between the concentrating chamber and the cathode chamber is a capping membrane; and the space between the concentrating chamber and the anode chamber is a capping membrane.

[0046] The anion and cation exchange membrane can be a homogeneous ion exchange membrane or a heterogeneous ion exchange membrane produced at home and abroad, such as AGU / CGU.

[0047] In the above steps, the number of the desalination chamber is at least one;

[0048] When the number of the desalination chamber is one, the arrangement of the concentration chamber, the buffer chamber and the desalination chamber is as follows:

[0049] In the above steps, the number of the buffer chambers is at least 2n, and the 2n buffer chambers are symmetrically distributed with the desalination chamber as the symmetry line, and the buffer chambers located at the distribution boundary are separated from the concentrating chamber;

[0050] For example, when there is one desalination chamber, 2n buffer chambers are symmetrically distributed with two consecutively arranged desalination chambers as the symmetry line, and the buffer chamber located at the distribution boundary is spaced apart from the concentrating chamber, such as Figure 2 As shown;

[0051] For example, when there is one desalination chamber and two buffer chambers, the two buffer chambers are symmetrically distributed with the desalination chamber as the symmetry line, and the buffer chamber located at the distribution boundary is spaced apart from the concentrating chamber, such as Figure 3 As shown;

[0052] For example, when there is one desalination chamber and four buffer chambers, the four buffer chambers are symmetrically distributed with the desalination chamber as the symmetry line, and the buffer chambers at the distribution boundary are spaced apart from the concentrating chamber, such as Figure 4 shown.

[0053] When the number of the desalination chambers is multiple, the arrangement of the concentrating chamber, the buffer chamber and the desalination chamber is [concentrating chamber-n buffer chambers-desalting chamber-n buffer chambers-concentrating chamber]m, wherein [concentrating chamber-n buffer chambers-desalting chamber-n buffer chambers-concentrating chamber] is a repeating unit, and the arrangement of the repeating unit is as follows: Figure 2 or Figure 3 or Figure 4 As shown, m is the number of repeating units. It can be seen that the number of the desalination chambers is m, that is, the number of the desalination chambers is consistent with the number of repeating units.

[0054] In the above steps, the buffer chambers symmetrically arranged on both sides of the desalination chamber and connected thereto are further provided with a feed port, a discharge port, a liquid storage tank, a circulation pump and a pipeline. The two symmetrically arranged buffer chambers are respectively connected to the liquid storage tank and the circulation pump through pipelines to form an independent circulation path;

[0055] In the above steps, a feed inlet, a discharge outlet, a liquid storage tank, a circulation pump, and a pipeline are provided in the concentrating chambers symmetrically disposed on both sides of the connected buffer chamber. The two symmetrically disposed concentrating chambers are connected to the liquid storage tank and the circulation pump respectively through pipelines to form independent circulation paths.

[0056] In the above steps, the cathode chamber and the anode chamber are both provided with a feed port and a discharge port;

[0057] In the above steps, the anode and the cathode are connected to the positive and negative poles of a power source.

[0058] In the above steps, by regulating the pH of the buffer chamber, the ion state of the target monobasic organic acid in the solution in the buffer chamber is increased, the ion state of the non-target monobasic organic acid is reduced, the non-target monobasic organic acid is retained in other buffer chambers, and the target monobasic organic acid is transferred from the desalination chamber to buffer chamber 1, buffer chamber 2, buffer chamber 3, ..., buffer chamber 1. n Migration can achieve low energy consumption, high efficiency and pollution-free separation of mixed monobasic organic acids in fermentation broth.

[0059] In step S1, the fermentation broth is a mixed monobasic organic acid with a concentration of 0.1-2.0 mol / L, specifically, the concentration of the mixed monobasic organic acid is 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.30 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, 0.60 mol / L, 0.65 mol / L, 0.7 mol / L, 0.75 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L L, 0.95mol / L, 1.0mol / L, 1.05mol / L, 1.1mol / L, 1.15mol / L, 1.2mol / L, 1.25mol / L, 1.30mol / L, 1.35mol / L, 1.4mol / L, 1.45mol / L, 1.5mol / L, 1.55mol / L, 1.60mol / L, 1.65mol / L, 1.7mol / L, 1.75mol / L, 1.8mol / L, 1.85mol / L, 1.9mol / L, 1.95mol / L or 2.0mol / L.

[0060] In step S2, the concentration of the first electrolyte solution is 0.05-1.0 mol / L, and the electrolyte of the first electrolyte solution is the target monobasic organic acid. Specifically, the concentration of the first electrolyte solution is 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.30 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, 0.60 mol / L, 0.65 mol / L, 0.7 mol / L, 0.75 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L or 1.0 mol / L.

[0061] In step S2, the pH is 0.5-4.0, specifically, the pH is 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9 or 4.0.

[0062] In step S3, the concentration of the second electrolyte solution is 0.1-1.0 mol / L, and the second electrolyte solution is a strong electrolyte solution. As an electrode solution, specifically, the concentration of the second electrolyte solution is 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.30 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, 0.60 mol / L, 0.65 mol / L, 0.7 mol / L, 0.75 mol / L, 0.8 mol / L, 0.85 mol / L, 0.9 mol / L, 0.95 mol / L or 1.0 mol / L.

[0063] In step S4, the mode of applying direct current is constant current density, and the current density is 0-50mA / cm 2 Specifically, the current density is 1 mA / cm 2 , 2mA / cm 2 , 3mA / cm 2 , 4mA / cm 2 , 5mA / cm 2 , 6mA / cm 2 , 7mA / cm 2 , 8mA / cm 2 , 9mA / cm 2 , 10mA / cm 2 , 11mA / cm 2 , 12mA / cm 2 , 13mA / cm 2 , 14mA / cm 2 , 15mA / cm 2 , 16mA / cm 2 , 17mA / cm 2 , 18mA / cm 2 , 19mA / cm 2 , 20mA / cm 2 , 21mA / cm 2 , 22mA / cm 2 , 23mA / cm 2 , 24mA / cm 2 , 25mA / cm 2 , 26mA / cm 2 , 27mA / cm 2 , 28mA / cm 2 , 29mA / cm 2 、30mA / cm 2 、31mA / cm 2 、32mA / cm2 、33mA / cm 2 、34mA / cm 2 、35mA / cm 2 、36mA / cm 2 、37mA / cm 2 、38mA / cm 2 、39mA / cm 2 , 40mA / cm 2 , 41mA / cm 2 , 42mA / cm 2 , 43mA / cm 2 , 44mA / cm 2 , 45mA / cm 2 , 46mA / cm 2 , 47mA / cm 2 , 48mA / cm 2 , 49mA / cm 2 or 50mA / cm 2 .

[0064] like Figure 2 As shown, according to an embodiment of the present invention, a device for pH control and separation of mixed monobasic organic acids in fermentation broth includes a desalination chamber, a buffer chamber connected and symmetrically arranged on both sides of the desalination chamber, a concentrating chamber connected and symmetrically arranged on both sides of the buffer chamber, a cathode chamber and an anode chamber respectively arranged on both sides of the connected concentrating chamber, a cathode arranged in the cathode chamber, and an anode arranged in the anode chamber;

[0065] The desalination chamber is used to introduce fermentation liquid;

[0066] The buffer chamber and the concentrating chamber are used to pass a first electrolyte solution;

[0067] The buffer chamber is also used to control pH;

[0068] The cathode and the anode are configured to be supplied with a direct current. Specific embodiment:

[0070] Example 1

[0071] use Figure 3 The device shown separates mixed pyruvic acid and acetic acid solutions, where the anode and cathode materials are corrosion-resistant titanium coated with ruthenium. The ion exchange membranes used in the membrane stack are CGU cation exchange membrane and AGU anion exchange membrane, with a single membrane effective area of 20 cm 2 .

[0072] Specific separation methods include:

[0073] Step S1, introducing 200 mL of a mixed solution of 0.3 mol / L pyruvic acid and 0.3 mol / L acetic acid into the desalination chamber;

[0074] Step S2: introducing a first electrolyte solution into the buffer chambers symmetrically disposed on both sides of the desalination chamber and connected thereto, and into the concentrating chambers symmetrically disposed on both sides of the connected buffer chamber and connected thereto, wherein the first electrolyte solution is a pyruvic acid solution. 200 mL of a 0.1 mol / L pyruvic acid solution is introduced into the concentrating chambers, and the pH of the solution in the buffer chamber 1 is adjusted to 2.0 by the pyruvic acid solution.

[0075] Step S3: introducing a second electrolyte solution (the second electrolyte solution is 200 mL of 0.3 mol / L dilute sulfuric acid, which serves as an electrode solution) into the cathode chamber and the anode chamber respectively disposed on both sides of the connected concentrating chamber;

[0076] Step S4: Apply direct current to the cathode disposed in the cathode chamber and the anode disposed in the anode chamber, using a constant current operation mode and setting the current density to 20 mA / cm 2 The linear velocity of the solution flow in each compartment is 3 cm / s.

[0077] During the above separation process, the concentration of acetic acid in the buffer chamber 1 and the concentration changes of pyruvic acid and acetic acid in the concentration chamber were recorded respectively. The results are as follows: Figure 5 shown.

[0078] During the above separation process, the device was operated for 240 minutes. The final separation factor between pyruvic acid and acetic acid was 9, the concentration of pyruvic acid in the concentrating chamber was 0.33 mol / L, and the purity was 95.1%.

[0079] Example 2

[0080] use Figure 4 The device shown separates mixed pyruvic acid and acetic acid solutions, where the anode and cathode materials are corrosion-resistant titanium coated with ruthenium. The ion exchange membranes used in the membrane stack are CGU cation exchange membrane and AGU anion exchange membrane, with a single membrane effective area of 20 cm 2 .

[0081] Specific separation methods include:

[0082] Step S1, introducing 200 mL of a mixed solution of 0.3 mol / L pyruvic acid and 0.3 mol / L acetic acid into the desalination chamber;

[0083] Step S2: introducing a first electrolyte solution into the buffer chambers symmetrically disposed on both sides of the desalination chamber and connected thereto, and into the concentrating chambers symmetrically disposed on both sides of the connected buffer chamber and connected thereto, wherein the first electrolyte solution is a pyruvic acid solution. 200 mL of a 0.1 mol / L pyruvic acid solution is introduced into the concentrating chambers, and the pyruvic acid solution is used to adjust the pH of the solutions in both buffer chambers 1 and 2 to 2.0.

[0084] Step S3: introducing a second electrolyte solution (the second electrolyte solution is 200 mL of 0.3 mol / L dilute sulfuric acid, which serves as an electrode solution) into the cathode chamber and the anode chamber respectively disposed on both sides of the connected concentrating chamber;

[0085] Step S4: Apply direct current to the cathode disposed in the cathode chamber and the anode disposed in the anode chamber, using a constant current operation mode and setting the current density to 20 mA / cm 2 The linear velocity of the solution flow in each compartment is 3 cm / s.

[0086] During the above separation process, the concentrations of acetic acid in buffer chamber 1 and buffer chamber 2, and the concentrations of pyruvic acid and acetic acid in the concentration chamber were recorded respectively. The results are as follows: Figure 6 shown.

[0087] During the above separation process, the electrodialysis unit operated for 240 minutes. The final separation factor between pyruvic acid and acetic acid was 11, the concentration of pyruvic acid in the concentrating compartment was 0.33 mol / L, and the purity was 95.9%.

[0088] Example 3

[0089] use Figure 3 The device shown separates mixed pyruvic acid and acetic acid solutions, where the anode and cathode materials are corrosion-resistant titanium coated with ruthenium. The ion exchange membranes used in the membrane stack are CGU cation exchange membrane and AGU anion exchange membrane, with a single membrane effective area of 20 cm 2 .

[0090] Specific separation methods include:

[0091] Step S1, introducing 200 mL of a mixed solution of 0.3 mol / L pyruvic acid and 0.3 mol / L acetic acid into the desalination chamber;

[0092] Step S2: introducing a first electrolyte solution into the buffer chambers symmetrically disposed on both sides of the desalination chamber and connected thereto, and into the concentrating chambers symmetrically disposed on both sides of the connected buffer chamber and connected thereto, wherein the first electrolyte solution is a pyruvic acid solution. 200 mL of a 0.1 mol / L pyruvic acid solution is introduced into the concentrating chambers, and the pH of the solution in the buffer chamber 1 is adjusted to 1.6 by the pyruvic acid solution.

[0093] Step S3: introducing a second electrolyte solution (the second electrolyte solution is 200 mL of 0.3 mol / L dilute sulfuric acid, which serves as an electrode solution) into the cathode chamber and the anode chamber respectively disposed on both sides of the connected concentrating chamber;

[0094] Step S4: Apply direct current to the cathode disposed in the cathode chamber and the anode disposed in the anode chamber, using a constant current operation mode and setting the current density to 20 mA / cm 2 The linear velocity of the solution flow in each compartment is 3 cm / s.

[0095] During the above separation process, the concentration of acetic acid in the buffer chamber 1 and the concentration changes of pyruvic acid and acetic acid in the concentration chamber were recorded respectively. The results are as follows: Figure 7 shown.

[0096] During the above separation process, the electrodialysis unit operated for 240 minutes. The final separation factor between pyruvic acid and acetic acid was 27, the concentration of pyruvic acid in the concentrating compartment was 0.34 mol / L, and the purity was 98.3%.

[0097] Example 4

[0098] Compared with Example 1, the difference is that the pH of the solution in the buffer chamber 1 is 1.4, and the rest are the same.

[0099] During the above separation process, the concentration of acetic acid in the buffer chamber 1 and the concentration changes of pyruvic acid and acetic acid in the concentration chamber were recorded respectively. The results are as follows: Figure 8 shown.

[0100] During the above separation process, the electrodialysis unit operated for 240 minutes. The final separation factor between pyruvic acid and acetic acid was 36, the concentration of pyruvic acid in the concentrating compartment was 0.34 mol / L, and the purity was 99.0%.

[0101] Example 5

[0102] Compared with Example 1, the difference is that the pH of the solution in the buffer chamber 1 is 1.2, and the rest are the same.

[0103] During the above separation process, the concentration of acetic acid in the buffer chamber 1 and the concentration changes of pyruvic acid and acetic acid in the concentration chamber were recorded respectively. The results are as follows: Figure 9 shown.

[0104] During the above separation process, the electrodialysis unit operated for 240 minutes. The final separation factor between pyruvic acid and acetic acid was 74, the concentration of pyruvic acid in the concentrating compartment was 0.34 mol / L, and the purity was 99.3%.

[0105] Example 6

[0106] Compared with Example 1, the difference is that the pH of the solution in the buffer chamber 1 is 1.2, and 1000 mL of a mixed solution of 0.3 mol / L pyruvic acid and 0.3 mol / L acetic acid is passed into the desalination chamber, and the rest are the same.

[0107] During the above separation process, the concentration of acetic acid in the buffer chamber 1 and the concentration changes of pyruvic acid and acetic acid in the concentration chamber were recorded respectively. The results are as follows: Figure 10 shown.

[0108] During the above separation process, the electrodialysis unit operated for 240 minutes. The final separation factor between pyruvic acid and acetic acid was 74, the concentration of pyruvic acid in the concentrating compartment was 0.90 mol / L, and the purity was 99.2%.

[0109] Example 7

[0110] Compared with Example 1, the difference is that the pH of the solution in the buffer chamber 1 is 1.3, and 200 mL of a mixed solution of 0.3 mol / L pyruvic acid and 0.3 mol / L formic acid is passed into the desalination chamber. The rest are the same.

[0111] During the above separation process, the concentration of formic acid in the buffer chamber 1 and the concentration changes of pyruvic acid and formic acid in the concentration chamber were recorded respectively. The results are as follows: Figure 11 shown.

[0112] During the above separation process, the electrodialysis unit operated for 240 minutes. The final separation factor between pyruvic acid and formic acid was 9, the concentration of pyruvic acid in the concentrating compartment was 0.35 mol / L, and the purity was 96.4%.

[0113] Example 8

[0114] Compared with Example 1, the difference is that the pH of the solution in the buffer chamber 1 is 1.3, and 200 mL of a mixed solution of 0.3 mol / L pyruvic acid, 0.3 mol / L acetic acid and 0.3 mol / L formic acid is passed into the desalination chamber, and the rest are the same.

[0115] During the above separation process, the concentration of the mixture of acetic acid and formic acid in the buffer chamber 1, the concentration of pyruvic acid in the concentration chamber, and the changes in the concentration of the mixture of acetic acid and formic acid were recorded respectively. The results are as follows: Figure 12 shown.

[0116] During the above separation process, the electrodialysis unit operated for 240 minutes, and the concentration of pyruvic acid in the concentrating compartment was 0.34 mol / L, with a purity of 96.7%.

[0117] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for separating mixed monobasic organic acids in a fermentation broth by pH control, characterized in that: include: introducing fermentation liquid into the desalination chamber; A first electrolyte solution is introduced into the buffer chambers connected and symmetrically arranged on both sides of the desalination chamber, and into the concentrating chambers connected and symmetrically arranged on both sides of the buffer chamber, and the pH of the solution in the buffer chamber is regulated by the first electrolyte solution; introducing a second electrolyte solution into the cathode chamber and the anode chamber respectively disposed on both sides of the connected concentrating chamber; Applying direct current to both ends of the cathode disposed in the cathode chamber and the anode disposed in the anode chamber to separate the mixed monobasic organic acid in the fermentation liquid; By regulating the pH of the buffer chamber, the ionic state of the target monobasic organic acid in the solution in the buffer chamber is increased, and the ionic state of the non-target monobasic organic acid is reduced, so that the non-target monobasic organic acid is retained in other buffer chambers, and the target monobasic organic acid migrates from the desalination chamber to buffer chamber 1, buffer chamber 2, buffer chamber 3, ..., buffer chamber n; The fermentation broth is a mixed monobasic organic acid with a concentration of 0.1-2.0 mol / L; The concentration of the first electrolyte solution is 0.05-1.0 mol / L, which is the target monobasic organic acid; The pH is 0.5-4.0; The concentration of the second electrolyte solution is 0.1-1.0 mol / L; The mode of applying direct current is constant current density, and the current density is 0-50 mA / cm 2 ; The space between the desalination chamber and the buffer chamber is an anion exchange membrane or a cation exchange membrane; the space between the buffer chamber and the concentration chamber is an anion exchange membrane or a cation exchange membrane; the space between the concentration chamber and the cathode chamber is a sealing membrane; the space between the concentration chamber and the anode chamber is a sealing membrane.

2. The method for separating a mixed monobasic organic acid in a fermentation broth by pH control according to claim 1, characterized in that: The number of the desalination chamber is at least one.

3. The method for separating a mixed monobasic organic acid in a fermentation broth by pH control according to claim 1, characterized in that: The number of the buffer chambers is at least 2n, where n is greater than or equal to 1; the 2n buffer chambers are symmetrically distributed with the desalination chamber as the symmetry line, and the buffer chambers located at the distribution boundary are spaced apart from the concentrating chamber.

4. A device for pH control and separation of mixed monobasic organic acids in fermentation broth, characterized in that: It includes a desalination chamber, a buffer chamber connected and symmetrically arranged on both sides of the desalination chamber, a concentrating chamber connected and symmetrically arranged on both sides of the buffer chamber, a cathode chamber and an anode chamber respectively arranged on both sides of the connected concentrating chamber, a cathode arranged in the cathode chamber and an anode arranged in the anode chamber; The desalination chamber is used to introduce fermentation liquid; The buffer chamber and the concentrating chamber are used to pass a first electrolyte solution; The buffer chamber is also used to control pH; The cathode and the anode are adapted to be supplied with direct current; By regulating the pH of the buffer chamber, the ionic state of the target monobasic organic acid in the solution in the buffer chamber is increased, and the ionic state of the non-target monobasic organic acid is reduced, so that the non-target monobasic organic acid is retained in other buffer chambers, and the target monobasic organic acid migrates from the desalination chamber to buffer chamber 1, buffer chamber 2, buffer chamber 3, ..., buffer chamber n; introducing a second electrolyte solution into the cathode chamber and the anode chamber respectively disposed on both sides of the connected concentrating chamber; The fermentation broth is a mixed monobasic organic acid with a concentration of 0.1-2.0 mol / L; The concentration of the first electrolyte solution is 0.05-1.0 mol / L, which is the target monobasic organic acid; The pH is 0.5-4.0; The concentration of the second electrolyte solution is 0.1-1.0 mol / L; The mode of applying direct current is constant current density, and the current density is 0-50 mA / cm 2 ; The space between the desalination chamber and the buffer chamber is an anion exchange membrane or a cation exchange membrane; the space between the buffer chamber and the concentration chamber is an anion exchange membrane or a cation exchange membrane; the space between the concentration chamber and the cathode chamber is a sealing membrane; the space between the concentration chamber and the anode chamber is a sealing membrane.

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