Regeneration method of anion exchange resin for refining starch sugar

Abstract

The invention discloses a regeneration method of anion exchange resin for refining starch sugar, and belongs to the technical field of ion exchange resin treatment methods. The method comprises the following steps: firstly, introducing a NaOH solution into a backwashed invalid anion resin, then carrying out desorption treatment on the NaOH solution under the assistance of microwaves, and finally, further desorbing with ozone to complete the regeneration of the anion exchange resin for refining starch sugar. According to the method, the temperature of the regeneration liquid is increased through microwave-assisted heating, the permeability of the resin is improved through ozone adsorption, the regeneration efficiency is improved, regeneration of the invalid anion exchange resin is achieved, the adsorption capacity of the regenerated resin can be recovered to 95% or above of the adsorption capacity of new resin, the consumption of the NaOH solution is low, and the regeneration time is short.

Description

Technical Field

[0001] The invention relates to a regeneration method of an anion exchange resin for starch sugar refining, belonging to the technical field of ion exchange resin treatment methods. Background Art

[0002] Starch syrup has a complex composition due to various impurities brought by raw materials, water and catalysts. These impurities can be divided into nitrogen-containing substances, organic acids, inorganic salts, fats, colored substances, etc. Their presence has an adverse effect on the quality of syrup and the production of crystallized glucose. Therefore, the saccharified liquid must be refined to remove these impurities as much as possible. Ion exchange resin has ion exchange and adsorption effects. After the starch saccharified liquid is decolorized by activated carbon, it is refined with ion exchange resin to remove almost all ash, organic acids, pigments and other impurities, further improving the purity. Among them, various anions, pigments, organic acids, proteins and other impurities except cations are adsorbed and removed by anion exchange resin. The saccharified liquid refined by ion exchange resin is used to produce maltose syrup, crystallized glucose or fructose syrup, and the product quality is greatly improved.

[0003] After the ion exchange resin has been used for a period of time, the impurities adsorbed are close to saturation, and regeneration treatment is required. Chemical agents such as acid and alkali are used to remove the ions and other impurities adsorbed by the resin to restore its original composition and performance. However, the current resin regeneration method has the disadvantages of long regeneration time, large acid and alkali consumption, and a large amount of external flushing wastewater, resulting in high regeneration costs for enterprises and great environmental pressure. Summary of the invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for regenerating anion exchange resin for starch sugar refining, and to achieve regeneration of failed anion exchange resin by microwave desorption and ozone desorption assisted by NaOH solution.

[0005] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows: A method for regenerating an anion exchange resin for starch sugar refining comprises the following steps: (1) Backflush the failed anion resin, and then pass NaOH solution into the backflushed failed anion resin. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 4-6 cm higher than the resin; (2) performing a microwave desorption treatment, during which the temperature of the feed liquid is controlled; (3) After the microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (4) Pass NaOH solution into the anion exchange resin. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 4-6 cm above the resin. (5) performing a secondary microwave desorption treatment, during which the temperature of the feed liquid is controlled; (6) After the second microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (7) Passing ozone gas from the bottom of the anion exchange resin column for further desorption; (8) Rinse the anion exchange resin with deionized water and soak it for later use to obtain the regenerated anion exchange resin.

[0006] Furthermore, in step (1) and step (4), the concentration of the NaOH solution is 3.5-4.5 wt.%, and the flow rate is 1.5-2.2 bv / h; the amount of NaOH solution used in step (1) is 0.8-1.5 bv, and the amount of NaOH solution used in step (4) is 0.8-1.2 bv.

[0007] Furthermore, in step (1) and step (4), the concentration of the NaOH solution is 3.8-4.1 wt.%, the flow rate is 1.6-2.0 bv / h, the amount of NaOH solution used in step (1) is 1.0-1.2 bv, and the amount of NaOH solution used in step (4) is 0.8-1.0 bv.

[0008] Furthermore, in step (2) and step (5), the microwave desorption is carried out in an intermittent treatment mode: microwave power is 300-500 W, irradiation time is 15-50 s, standby time is 3-8 min, and irradiation times are 2-5 times.

[0009] Furthermore, in step (2) and step (5), the microwave desorption is carried out in an intermittent treatment mode: microwave power is 380-450 W, irradiation is 25-40 s, standby is 4-6 min, and the number of irradiations is 3-4 times.

[0010] When the desorption system composed of resin and dilute alkali solution is placed in a microwave field, the resin is not easy to absorb microwaves and will not be significantly heated during the microwave regeneration process; due to the unique heating mechanism of microwaves and good heat conversion efficiency, the dilute alkali solution quickly absorbs microwaves and is heated, and quickly diffuses into the resin pores to react with the adsorbed impurities. The good mass transfer and heat transfer effects improve the utilization rate of the alkali, allowing the impurities adsorbed by the resin to be quickly desorbed and diffused out from the resin pores.

[0011] Furthermore, in step (2) and step (5), the temperature of the feed solution is controlled not to exceed 70° C. during the microwave desorption treatment.

[0012] Furthermore, in step (2) and step (5), the temperature of the feed solution is controlled not to exceed 65° C. during the microwave desorption treatment.

[0013] The maximum temperature tolerance of the strongly alkaline macroporous anion exchange resin used in the starch sugar separation process is generally 80°C. Too high a feed liquid temperature can easily destroy the internal pore structure of the resin, resulting in reduced resin adsorption performance.

[0014] Furthermore, in step (3), step (6) and step (8), the end point of flushing the anion exchange resin is when the pH of the eluate is 6.0-7.0.

[0015] Furthermore, in step (7), the ozone intake flow rate is 12-20 L / h, and the intake time is 15-25 min.

[0016] Furthermore, in step (7), the ozone intake flow rate is 14-17 L / h, and the intake time is 18-21 min.

[0017] After microwave desorption assisted by NaOH solution, a small amount of organic impurities will still remain on the inner wall of the resin pores. Ozone can penetrate into the resin pores to react chemically with organic matter, and the impurities attached to the inner wall of the resin pores are further desorbed, so that the resin pores are effectively regenerated, thereby restoring the corresponding adsorption capacity of the anion exchange resin. In addition, as the operation time of the resin column increases, biological bacteria will also grow on the resin. The biological bacteria adhere to the surface of the resin and the inner wall of the pores, causing some pores of the resin to be blocked. Ozone has a disinfecting and sterilizing effect, which can kill and remove biological bacteria, improve the permeability of the resin, and improve the regeneration efficiency.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a method for regenerating an anion exchange resin for starch sugar refining, which adopts a method of first microwave-assisted NaOH solution desorption and then ozone desorption to complete the regeneration of the anion exchange resin for starch sugar refining, and improves the regeneration efficiency by increasing the temperature of the regeneration liquid and improving the permeability of the resin. After regeneration, the adsorption capacity of the resin can be restored to more than 95% of the adsorption capacity of the new resin.

[0019] (2) The anion exchange resin regeneration method of the present invention is simple and easy to operate, and the consumption of NaOH solution is reduced by more than 10%, and the regeneration time is shortened by more than 1 hour, which can reduce production costs, improve economic benefits, and reduce resource waste and environmental pollution. DETAILED DESCRIPTION

[0020] Example 1 A method for regenerating an anion exchange resin for starch sugar refining comprises the following steps: (1) Backflush the failed anion resin, and then pass a 3.8wt.% NaOH solution into the backflushed spent anion resin at a flow rate of 1.6bv / h and a NaOH solution dosage of 1.2bv. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 5cm above the resin; (2) Perform a microwave desorption treatment with a microwave power of 380 W, irradiation for 40 seconds, standby for 6 minutes, and irradiation times of 3 times, during which the feed liquid temperature is controlled not to exceed 65 °C; (3) After the microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (4) Pass a 3.8 wt.% NaOH solution into the anion exchange resin at a flow rate of 1.6 bv / h and a NaOH solution dosage of 0.8 bv. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 5 cm above the resin; (5) Perform secondary microwave desorption treatment, microwave power 380W, irradiation 40s, standby 6min, irradiation times 3 times, during which the feed liquid temperature is controlled not to exceed 65°C; (6) After the second microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (7) Pass ozone gas from the bottom of the anion exchange resin column at an ozone inlet flow rate of 17 L / h and an inlet time of 18 min for further desorption; (8) Rinse the anion exchange resin with deionized water and soak it for later use to obtain the regenerated anion exchange resin.

[0021] Example 2 A method for regenerating an anion exchange resin for starch sugar refining comprises the following steps: (1) Backflush the failed anion resin, and then pass a 4.1wt.% NaOH solution into the backflushed spent anion resin at a flow rate of 2.0bv / h and a NaOH solution dosage of 1.0bv. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 5cm above the resin; (2) Perform a microwave desorption treatment, with a microwave power of 450 W, irradiation for 25 seconds, standby for 4 minutes, and irradiation times of 4 times, during which the feed liquid temperature is controlled not to exceed 65 °C; (3) After the microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (4) Pass a 4.1 wt.% NaOH solution into the anion exchange resin at a flow rate of 2.0 bv / h and a NaOH solution dosage of 1.0 bv. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 5 cm above the resin; (5) Perform secondary microwave desorption treatment, microwave power 450W, irradiation 25s, standby 4min, irradiation times 4 times, during which the feed liquid temperature is controlled not to exceed 65°C; (6) After the second microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (7) Pass ozone gas from the bottom of the anion exchange resin column at an ozone inlet flow rate of 14 L / h and an inlet time of 21 min for further desorption; (8) Rinse the anion exchange resin with deionized water and soak it for later use to obtain the regenerated anion exchange resin.

[0022] Example 3 A method for regenerating an anion exchange resin for starch sugar refining comprises the following steps: (1) Backflush the failed anion resin, and then pass a 3.5wt.% NaOH solution into the backflushed spent anion resin at a flow rate of 2.2bv / h and a NaOH solution dosage of 1.5bv. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 5cm above the resin; (2) Perform a microwave desorption treatment, with a microwave power of 300 W, irradiation for 50 seconds, standby for 3 minutes, and irradiation times of 5 times, during which the feed liquid temperature is controlled not to exceed 65 °C; (3) After the microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (4) Pass a 3.5 wt.% NaOH solution into the anion exchange resin at a flow rate of 2.2 bv / h and a NaOH solution dosage of 1.2 bv. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 5 cm above the resin; (5) Perform secondary microwave desorption treatment, microwave power 30W, irradiation 50s, standby 3min, irradiation times 5 times, during which the feed liquid temperature is controlled not to exceed 65℃; (6) After the second microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (7) Pass ozone gas from the bottom of the anion exchange resin column at an ozone inlet flow rate of 12 L / h and an inlet time of 25 min for further desorption; (8) Rinse the anion exchange resin with deionized water and soak it for later use to obtain the regenerated anion exchange resin.

[0023] Example 4 A method for regenerating an anion exchange resin for starch sugar refining comprises the following steps: (1) Backflush the failed anion resin, and then pass a 4.5wt.% NaOH solution into the backflushed spent anion resin at a flow rate of 1.5bv / h and a NaOH solution dosage of 0.8bv. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 5cm above the resin; (2) Perform a microwave desorption treatment with a microwave power of 500 W, irradiation for 15 seconds, standby for 8 minutes, and irradiation times of 2 times, during which the feed liquid temperature is controlled not to exceed 65°C; (3) After the microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (4) Pass a 4.5 wt.% NaOH solution into the anion exchange resin at a flow rate of 1.5 bv / h and a NaOH solution dosage of 0.8 bv. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 5 cm above the resin; (5) Perform secondary microwave desorption treatment, with a microwave power of 500 W, irradiation for 15 seconds, standby for 8 minutes, and irradiation times of 2 times, during which the feed liquid temperature was controlled not to exceed 65°C; (6) After the second microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (7) Pass ozone gas from the bottom of the anion exchange resin column at a flow rate of 20 L / h and a gas injection time of 15 min for further desorption; (8) Rinse the anion exchange resin with deionized water and soak it for later use to obtain the regenerated anion exchange resin.

[0024] Comparative Example 1 No microwave desorption treatment was performed, and the remaining steps were the same as in Example 2.

[0025] Comparative Example 2 Step (7) is not performed, and the remaining steps are the same as those in Example 2.

[0026] Comparative Example 3 Microwave desorption treatment and step (7) were not performed, and the remaining steps were the same as those in Example 2.

[0027] Experimental Example 1 The regenerated anion exchange resins of Examples 1-4 were tested for adsorption capacity, and the ratios of their adsorption amounts are listed in Table 1.

[0028] In order to compare the adsorption capacity of regenerated anion exchange resin and reduce the interference of external factors, the ratio of the adsorption capacity of regenerated anion exchange resin and new resin under the same adsorption conditions is used to reflect it.

[0029] Table 1. Ratio of adsorption amount As can be seen from Table 1, the ratio of the adsorption capacity of the regenerated anion exchange resin in Example 1 is 95.51%, the ratio of the adsorption capacity of the regenerated anion exchange resin in Example 2 is 96.27%, the ratio of the adsorption capacity of the regenerated anion exchange resin in Example 3 is 95.69%, and the ratio of the adsorption capacity of the regenerated anion exchange resin in Example 4 is 95.92%. It can be seen that the ratio of the adsorption capacity of the regenerated anion exchange resin obtained by the method of the present invention to the adsorption capacity of the new resin is higher than 95%, indicating that the adsorption capacity of the regenerated anion exchange resin is high.

[0030] Experimental Example 2 The adsorption capacity of the regenerated anion exchange resins of Example 2 and Comparative Examples 1-3 was tested, and the ratios of their adsorption amounts are listed in Table 2.

[0031] In order to compare the adsorption capacity of regenerated anion exchange resin and reduce the interference of external factors, the ratio of the adsorption capacity of regenerated anion exchange resin and new resin under the same adsorption conditions is used to reflect it.

[0032] Table 2. Ratio of adsorption amount As can be seen from Table 2, the adsorption ratio of the regenerated anion exchange resin in Example 2 is 96.27%, the adsorption ratio of the regenerated anion exchange resin in Comparative Example 1 is 92.37%, the adsorption ratio of the regenerated anion exchange resin in Example 3 is 91.53%, and the adsorption ratio of the regenerated anion exchange resin in Example 4 is 90.02%. It can be seen that the present invention adopts the method of first microwave-assisted NaOH solution desorption and then ozone desorption to complete the regeneration of the anion exchange resin for starch sugar refining, which can effectively improve the adsorption capacity of the regenerated anion exchange resin.

[0033] Experimental Example 3 The current process in the workshop is: add NaOH solution (concentration 4.0±0.2Bè) to the anion resin after backwashing. The flow rate of NaOH solution is 1.5-2.5bv / h, and the amount of NaOH solution is 3.5-4.5bv. Soak for 2 hours and rinse with deionized water until the pH value of the eluate is 6-8.

[0034] The sodium hydroxide savings and regeneration time of Examples 1-4 and the current process in the workshop are listed in Table 3.

[0035] Table 3. Sodium hydroxide savings and regeneration time The amount of sodium hydroxide saved by the current process in the workshop is recorded as 0.

[0036] As can be seen from Table 3, the sodium hydroxide saving in Example 1 is 11.01%, and the regeneration time is 6-8h; the sodium hydroxide saving in Example 2 is 11.54%, and the regeneration time is 6-8h; the sodium hydroxide saving in Example 3 is 10.63%, and the regeneration time is 7-8h; the sodium hydroxide saving in Example 4 is 10.92%, and the regeneration time is 7-8h. The regeneration time of the current workshop process is 8-9h. It can be seen that the present invention can reduce the consumption of sodium hydroxide and shorten the regeneration time compared with the current workshop process.

Claims

1. A method for regenerating an anion exchange resin for starch sugar refining, characterized in that: The steps include: (1) Backflush the failed anion resin, and then pass NaOH solution into the backflushed failed anion resin. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 4-6 cm higher than the resin; (2) performing a microwave desorption treatment, during which the temperature of the feed liquid is controlled; (3) After the microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (4) Pass NaOH solution into the anion exchange resin. When the discharge concentration is the same as the feed concentration, stop feeding and keep the liquid level 4-6 cm above the resin. (5) performing a secondary microwave desorption treatment, during which the temperature of the feed liquid is controlled; (6) After the second microwave desorption treatment is completed, the anion exchange resin is rinsed with deionized water; (7) Passing ozone gas from the bottom of the anion exchange resin column for further desorption; (8) Rinse the anion exchange resin with deionized water and soak it for later use.

2. The method for regenerating anion exchange resin for starch sugar refining according to claim 1, characterized in that: In step (1) and step (4), the concentration of the NaOH solution is 3.5-4.5 wt.%, and the flow rate is 1.5-2.2 bv / h; the amount of NaOH solution used in step (1) is 0.8-1.5 bv, and the amount of NaOH solution used in step (4) is 0.8-1.2 bv.

3. The method for regenerating anion exchange resin for starch sugar refining according to claim 2, characterized in that: In step (1) and step (4), the concentration of the NaOH solution is 3.8-4.1 wt.%, the flow rate is 1.6-2.0 bv / h, the amount of NaOH solution used in step (1) is 1.0-1.2 bv, and the amount of NaOH solution used in step (4) is 0.8-1.0 bv.

4. The method for regenerating anion exchange resin for starch sugar refining according to claim 1, characterized in that: In step (2) and step (5), the microwave desorption adopts an intermittent treatment method: microwave power 300-500W, irradiation 15-50s, standby 3-8min, and irradiation times 2-5 times.

5. The method for regenerating anion exchange resin for starch sugar refining according to claim 4, characterized in that: In step (2) and step (5), the microwave desorption adopts an intermittent treatment method: microwave power 380-450W, irradiation 25-40s, standby 4-6min, and irradiation times 3-4 times.

6. The method for regenerating anion exchange resin for starch sugar refining according to claim 1, characterized in that: In step (2) and step (5), the temperature of the feed solution is controlled not to exceed 70° C. during the microwave desorption treatment.

7. The method for regenerating anion exchange resin for starch sugar refining according to claim 6, characterized in that: In step (2) and step (5), the temperature of the feed solution is controlled not to exceed 65° C. during the microwave desorption treatment.

8. The method for regenerating anion exchange resin for starch sugar refining according to claim 1, characterized in that: In step (3), step (6) and step (8), the end point of flushing the anion exchange resin is when the pH of the eluate is 6.0-7.

0.

9. The method for regenerating anion exchange resin for starch sugar refining according to claim 1, characterized in that: In step (7), the ozone intake flow rate is 12-20 L / h, and the intake time is 15-25 min.

10. The method for regenerating anion exchange resin for starch sugar refining according to claim 9, characterized in that: In step (7), the ozone intake flow rate is 14-17 L / h, and the intake time is 18-21 min.

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