CN1191220C - Process for desalting 1,3-propylene glycol fermentation liquor by electricity dialysis - Google Patents

Abstract

The present invention discloses a process for desalting 1, 3-propanediol fermentation liquid by an electric dialysis process, which relates to the technical field of the desalinization of the 3-propanediol fermentation liquid, particularly to the technical field of the desalinization of the 3-propanediol fermentation liquid by the electric dialysis process. The process is characterized in that in the selection of main parameters, the initial concentration of a salt solution filled into a strong chamber tank is from 0.01 mol/L to 0.05 mol/L; the flow speed of the 3-propanediol fermentation liquid in a weak chamber is from 40 L/h to 80 L/h; the flow speed of the salt solution in a strong chamber is from 40 L/h to 80 L/h; the voltage of a single film pair is from 0.5V to 1.4V. The method can effectively eliminate an organic acid salt and an inorganic salt in 1, 3-propanediol, so the product loss rate is greatly reduced, and subsequent extraction operation is easy.

Description

Desalination Process of 1,3-Propanediol Fermentation Broth by Electrodialysis

Technical field:

The electrodialysis method is used in the desalination process of 1,3-propanediol fermentation liquid, and relates to the technical field of desalination of fermentation liquid, especially relates to the technical field of desalination of fermentation liquid by electrodialysis.

Background technique:

1,3-Propanediol is an important chemical raw material, mainly used as a monomer for the production of polyester and polyurethane. The production of 1,3-propanediol by fermentation has become a focus of domestic and foreign researchers in recent years because of its low cost and mild reaction conditions. However, organic acid by-products such as acetic acid and lactic acid will be generated during the fermentation process, which will reduce the pH value of the fermentation broth, thereby inhibiting the growth of bacteria and resulting in a low yield of 1,3-propanediol. Therefore, it is necessary to add potassium hydroxide during fermentation to adjust the pH value to about 7 to ensure the normal growth of the bacteria. The added potassium hydroxide will form organic acid salts with organic acids, plus a certain amount of inorganic salts contained in the culture medium itself, so that there are a large amount of organic acid salts and inorganic salts in the 1,3-propanediol product liquid obtained by fermentation . In the subsequent extraction of 1,3-propanediol dehydration by vacuum distillation, the presence of salt will lead to a continuous increase in vacuum distillation temperature and increased energy consumption; as the salt is precipitated in solid form, part of the 1,3-propanediol product will be wrapped Among them, the product loss rate of more than 20% is caused; at the same time, the concentration rate of the product is not higher than 30%-40%. Therefore, effectively removing a large amount of organic acid salts and inorganic salts present in 1,3-propanediol becomes a key part in the subsequent extraction of 1,3-propanediol. At present, there are no relevant literature reports that can effectively solve this problem at home and abroad.

Electrodialysis technology is one of the effective methods for separating electrolytes and non-electrolytes. It has been very mature in seawater desalination and fresh water purification. This method will not cause environmental pollution in application, and the cost is relatively low. It is gradually applied to the separation and recovery of organic acids and organic acid salts in fermentation broth. Usually electrodialysis is used for fermented liquid, mainly is to remove organic acid or organic acid salt as main product, for example in the process of producing lactic acid by fermentation method, lactic acid is separated from other substances in fermented liquid by electrodialysis technology (Li Xuemei etc. Fermented liquid Electrodialysis separation of lactic acid in medium. Journal of Chemical Engineering of Universities, 1998, 12 (3): 231-235), in the process of fermentative production of lactic acid, sodium lactate is converted into lactic acid by electrodialysis technology (L.Madzingaidzo et al. Process development and optimization of lactic acid purification using electrodialysis. Journal of biotechnology, 2002, 96: 223-239), etc. In the process operation of electrodialysis for fermentation liquid, the process conditions and operating parameters are very different for different operation objects. In the desalination process of 1,3-propanediol fermentation liquid, the salt It is removed from the fermentation broth as a by-product, which has not been studied at home and abroad.

Invention content:

According to the characteristics of 1,3-propanediol, the present invention proposes an electrodialysis method for the desalination process of 1,3-propanediol fermentation liquid, which can effectively remove organic acid salts and inorganic salts in 1,3-propanediol fermentation liquid Salt can greatly reduce the loss rate of the product.

The present invention contains following steps:

1) load the 1,3-propanediol fermented liquid to be treated in the weak room tank (7), load the salt solution in the concentrated room tank (4), load the acid solution in the anode room tank (6), and Load alkaline solution in the cathode chamber tank (5);

2) Open and control the pump (8A) of the above-mentioned thick chamber tank (4), control the pump (8D) of the above-mentioned dilute chamber tank (7), control the pump (8C) of the above-mentioned anode chamber tank (6), control the above-mentioned cathode chamber tank The pump (8B) of (5) makes above-mentioned saline solution, 1,3-propanediol fermented liquid, acid solution, alkaline solution circulate in electrodialyzer; Control the flow velocity of above-mentioned saline solution by regulating flow meter (9A), by adjusting The flow meter (9D) controls the flow rate of the above-mentioned 1,3-propanediol fermentation broth; the flow rate of the above-mentioned alkali solution is controlled by adjusting the flow meter (9B); the flow rate of the above-mentioned acid solution is controlled by adjusting the flow meter (9C);

3) Turn on and adjust the DC power supply (2), apply voltage to the single-membrane pair, and make the electrodialyzer work;

4) Turn off the DC power supply (2) and the pump (8A-8D);

It is characterized in that, in the above-mentioned step 1), the initial concentration of the salt solution loaded in the concentrated chamber tank (7) is 0.01mol/L～0.05mol/L; in the above-mentioned step 2), the above-mentioned 1, The flow rate of 3-propanediol fermented liquid is adjusted to be 40L/h～80L/h, and the flow rate of described salt solution is adjusted to be 40L/h～80L/h; In the above-mentioned 3rd) step, adjust DC power supply (2) to be single-membrane pair The added voltage is 0.5V ~ 1.4V.

Experiments have proved that using the electrodialysis method proposed by the present invention for the desalination process of 1,3-propanediol fermentation broth can effectively remove organic acid salts and inorganic salts in 1,3-propanediol, so that 1,3 - The product loss rate of propylene glycol is greatly reduced, and the expected purpose is achieved.

Description of drawings:

Fig. 1 is the working schematic diagram of the electrodialyzer used in the present invention.

Detailed ways:

A specific embodiment of the present invention will be described with reference to FIG. 1 .

The process device used in the present invention mainly includes an electrodialyzer 1, a DC stabilized power supply 2, an ammeter 3, a pump 8A-8D, and a flow meter 9A-9D, as shown in FIG. 1 . Among them, electrodialyzer 1 is a conventional electrodialyzer, which is composed of 10 pairs of anion and cation exchange membranes (single membrane area: 100×300mm ² -400×1600mm ² ), where A is an anion exchange membrane and C is a cation exchange membrane , what the present invention adopts is the homogeneous ion-exchange membrane of strong acid and strong alkali resistance of Beijing Huanyu Lida Environmental Protection Equipment Company.

During operation, the initial concentration of the salt solution in the concentrated chamber tank 4, the flow rate of the 1,3-propanediol fermentation broth in the weak chamber tank 7, the flow rate of the salt solution in the concentrated chamber tank 4, and the applied single-membrane pair voltage are very critical It is necessary to calculate and compare the three indicators of desalination time, energy consumption, and desalination rate in the actual desalination process to obtain the optimal value. The present invention calculates the 1,3-propanediol in the electrodialysis desalination process to achieve the same desalination rate The desalination effect is measured by the required energy consumption and desalination time, and the optimal range of the above parameters is determined at the same time. The determination of the desalination rate is characterized by measuring the initial and final conductivity values of the fermentation broth with a conductivity meter. The energy consumption Determined by the formula: energy consumption = operating voltage × current × operating time to determine.

The following 8 sets of experiments are used to illustrate:

Test 1:

1) Load 3 liters of 1,3-propanediol fermentation broth to be treated in the light chamber tank 7 (its conductivity value is measured to be 15000 μs/cm), and the concentration chamber tank 4 is filled with acetic acid with a concentration of 0.01mol/L 3 liters of potassium solutions, the anode chamber tank 6, the concentration of packing into is 2 liters of sulfuric acid solution of 0.05mol/L, and the concentration of loading in the cathode chamber tank 5 is 2 liters of sodium hydroxide solution of 0.05mol/L.

2) Turn on the pumps 8A-8D to circulate the salt solution, 1,3-propanediol fermentation broth, acid solution, and alkali solution in the electrodialyzer 1, and adjust the flow meters 9A and 9D to make the potassium acetate solution flow rate in the concentrated chamber tank 4 In the tank 7 of the dilute chamber, the flow rate of the 1,3-propanediol fermentation broth reaches 60L/h, and the flowmeters 9B and 9C are adjusted so that the flow rate of the sodium hydroxide solution in the cathode chamber tank 5 and the flow rate of the sulfuric acid solution in the anode chamber tank 6 reach 40L/h , cycle for 30 minutes.

3) Turn on the DC power supply 2 and adjust it to 5V so that the voltage on the single-membrane pair is 0.5V, and the electrodialyzer 1 starts to work.

4) When the conductivity value drops to 600 μs/cm, turn off the DC power supply 2 and turn off the pumps 8A-8D. At this time, the working time of the electrodialysis was measured to be 16 hours.

After the operation, through calculation, the energy consumption required for the electrodialysis desalination process is 5.36wh/L.

In the following 7 groups of experiments, the present invention has only changed the initial concentration of potassium acetate solution in the thick chamber tank 4, the flow velocity of the 1,3-propanediol fermentation liquid in the weak chamber tank 7, the flow velocity of the potassium acetate solution in the thick chamber tank 4 and the single The voltage value of the membrane pair, and other parameters are kept constant. When the same conductivity is reached (the conductivity drops from 15000s/cm to 600s/cm), the time used is measured and the energy consumption is calculated. The eight sets of data obtained from the experiment are shown in Table 1. group Initial concentration of salt solution in the concentrated chamber tank (mol/L) Fermentation broth flow rate in the thin chamber (L/h) Flow rate of saline solution in concentrated chamber tank (L/h) Single membrane pair voltage (V) Working hours (h) Energy Consumption(wh/L) 1 0.01 60 60 0.5 16 5.36 2 0.01 60 60 0.7 12 7.01 3 0.01 60 60 1.0 9 11.12 4 0.01 60 60 1.4 6 16.9 5 0.03 60 60 0.7 11.5 8.67 6 0.05 60 60 0.7 13 8.68 7 0.05 40 40 0.7 12 7.52 8 0.05 80 80 0.7 12 7.68

Table 1

As can be seen from the table, when the initial concentration of the salt solution in the thick chamber tank 4 is at 0.01～0.05mol/L, the flow rate of the 1,3-propanediol fermentation broth and the thick chamber tank at 40～80L in the weak chamber tank /h, when the voltage applied to the single-membrane pair is 0.5V-1.4V, the fermentation broth can achieve a higher desalination rate (conductivity), and when the same desalination rate is achieved, the required working time and required The energy consumption is not large. When the voltage of the single-membrane pair is higher, the required time is shorter and the energy consumption is slightly larger; when the voltage of the single-membrane pair is lower, the required time is longer and the energy consumption is smaller, but the required time and energy consumption can reach a relative balance.

In the electrodialysis desalination process, the initial concentration of the anode and cathode chambers, the flow rate of the acid and alkali solutions have little effect on the desalination effect, and the parameter range commonly used in the electrodialysis process of the fermentation broth can be selected: the flow rate of the anode chamber and the cathode chamber 20L/h-60L/h; the concentration of acid and lye in the anode chamber and cathode chamber is 0.01mol/L-0.1mol/L.

Use HPLC to measure the initial concentration C1 of 1,3-propanediol in the fermentation broth, and the concentration _C2 of 1,3-propanediol after desalination, and calculate the loss rate of 1,3-propanediol ((C ₁ -C ₂ )/C ₁ ) is only 4.5%-6.0%. When the 1,3-propanediol fermentation broth desalted by this technology is processed by distillation and other processes, the concentration rate can reach more than 70% at one time.

It is proved by experiments that the removal of the by-product salt in the 1,3-propanediol fermentation liquid by electrodialysis can achieve obvious effect and make the follow-up extraction work more smoothly.

Claims (1)

1, electroosmose process is used for 1, and the desalinating process of ammediol fermented liquid contains following steps:

1) in light chamber jar (7), pack into pending 1, ammediol fermented liquid, the salts solution of in dense chamber jar (4), packing into, the acid solution of in anolyte compartment's jar (6), packing into, the alkaline solution of in cathode compartment jar (5), packing into;

2) open the pump (8A) of controlling above-mentioned dense chamber jar (4), control the pump (8D) of above-mentioned light chamber jar (7), control the pump (8C) of above-mentioned anolyte compartment jar (6), control the pump (8B) of above-mentioned cathode compartment jar (5), make above-mentioned salts solution, 1, ammediol fermented liquid, acid solution, alkaline solution circulate in electrodialyzer; By regulating the flow velocity of the above-mentioned salts solution of under meter (9A) control, above-mentioned 1 by regulating under meter (9D) control, the flow velocity of ammediol fermented liquid; By regulating the flow velocity of the above-mentioned alkaline solution of under meter (9B) control; By regulating the flow velocity of the above-mentioned acid solution of under meter (9C) control;

3) open and regulate direct supply (2), for monofilm to adding voltage, make electrodialyzer work;

4) close direct supply (2) and pump (8A-8D);

It is characterized in that the above-mentioned the 1st) in the step, the starting point concentration of the salts solution of packing in the described dense chamber jar (7) is 0.01mol/L～0.05mol/L; The above-mentioned the 2nd) in the step, described 1, the flow rate regulation of ammediol fermented liquid is 40L/h～80L/h, and the flow rate regulation of described salts solution is 40L/h～80L/h; The above-mentioned the 3rd) in the step, regulating direct supply (2) is 0.5V～1.4V for monofilm to the voltage that adds.

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