A method for continuous decolorization in potassium sorbate production

Abstract

The present invention belongs to the technical field of potassium sorbate production, and specifically relates to a method for continuous decolorization in potassium sorbate production, which comprises: 1) pretreatment of an adsorption resin column, using an ethanol solution with a mass concentration of 50-75%, heating it to 40-70°C, continuously injecting it into the adsorption column, and then continuously discharging it; washing it with hot water after washing; 2) the neutralized potassium sorbate aqueous solution continuously enters the adsorption resin column, and the feed temperature is 50-85°C; 3) the transmittance of the potassium sorbate aqueous solution after decolorization is increased from 80% to 85-95%; 4) continuously decolorizing until the transmittance of the potassium sorbate aqueous solution is ≤85%, switching the feed to another decolorization column, and analyzing the adsorption saturated resin column, and sampling and analyzing the analytical solution. The method uses a new resin instead of activated carbon to realize a continuous decolorization process, has a large processing capacity, greatly reduces industrial production costs, and improves product quality; solves the problem of difficulty in regenerating activated carbon, and reduces environmental pollution at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of potassium sorbate production, and particularly relates to a continuous decolorization method in potassium sorbate production. Background Art

[0002] Potassium sorbate, alias: potassium 2,4-hexadienoate; English name: 2,4-Hexadienoic acid, potassium salt, (E,E)-; Potassium sarbate; Appearance: white flaky crystals, odorless or slightly odorous. Solubility: soluble in water, slightly soluble in ethanol and propylene glycol; Molecular formula: C6H7KO2; Molecular weight: 150.2; Melting point :-7.5; Density (g / ml, 25 / 4℃): 1.363.

[0003] Like sorbic acid, potassium sorbate is an internationally recognized low-toxic, highly effective acid-type preservative, and has the same preservative effect as sorbic acid. Potassium sorbate can effectively inhibit the activity of molds, yeasts and aerobic bacteria, and can also prevent the growth and reproduction of harmful microorganisms such as Clostridium botulinum, Staphylococcus aureus, and Salmonella, but is almost ineffective against beneficial microorganisms such as anaerobic spore-forming bacteria and Lactobacillus acidophilus. Its inhibitory effect is stronger than its bactericidal effect, thereby effectively extending the shelf life of food and maintaining the original flavor of food. Its preservative effect is 5-10 times that of similar products such as sodium benzoate. At present, potassium sorbate has been widely used in food, beverages, pickles, tobacco, medicine, cosmetics, agricultural products, pet and poultry feed and other industries. Judging from the development trend, its application range is still expanding.

[0004] Prior art synthesis process: The decolorization process currently used in the production process of sorbic acid is activated carbon decolorization. The activated carbon after decolorization contains adsorbed potassium sorbate and tar. Conventional treatment is directly treated as solid waste, which will bring a large amount of solid waste and increase production costs. Patent CN108043377A mentions that water washing and then steam desorption are used to remove adsorbed potassium sorbate and tar impurities, and the regenerated activated carbon is decolorized again, but the transmittance deviation of the potassium sorbate product obtained by reprocessing and decolorization is only 75%; Patent CN203079884U mentions a potassium sorbate continuous decolorization device, this process involves a three-stage decolorization device, and the other stage is standby. The decolorization rate of each stage involved in the three-stage decolorization is not high. This is because the adsorption rate of the activated carbon itself is low, and the activated carbon replaced at the same time is returned to the factory for recycling after recovering potassium sorbate, and cannot be reused. Summary of the invention

[0005] In order to solve the above problems, a method for continuous decolorization in potassium sorbate production is disclosed. The method adopts a new resin instead of activated carbon to realize a continuous decolorization process, effectively reduce the chloride ion content in the potassium sorbate solution, have a large processing capacity, can greatly reduce industrial production costs, and improve product quality; solve the problem of difficulty in regenerating activated carbon, and reduce environmental pollution at the same time, which is a new decolorization process that is more environmentally friendly.

[0006] The technical solution of the present invention is as follows:

[0007] A method for continuous decolorization in potassium sorbate production comprises the following steps:

[0008] 1) Pretreatment of the adsorption resin column, using ethanol solution to continuously inject into the adsorption column and then continuously discharge, m (ethanol solution): m (resin) = 1-3: 1, the cleaning time is 3-10 hours; after cleaning, it is washed with hot water, the water temperature is 50-90°C, m (water): m (resin) = 1-5: 1, the cleaning time is 4-8 hours, and the ethanol content in the water is <0.03%;

[0009] 2) the neutralized potassium sorbate aqueous solution continuously enters the adsorption resin column, wherein the concentration of the neutralized potassium sorbate aqueous solution is 38-60%, and the pH is 8.0-11; the feed temperature is 50-85° C., the residence time of the neutralized solution feed is 0.5-5 h, and the resin column is kept warm;

[0010] 3) After decolorization, the transmittance of the potassium sorbate aqueous solution is increased from 80% to 85-95%, the transmittance of the finished potassium sorbate is 98.0-98.5%, and the decolorization yield is 99.0-99.5%;

[0011] 4) Continuously decolorize until the transmittance of the potassium sorbate aqueous solution is ≤85%, switch the feed to another decolorization column, adsorb the saturated resin column for analysis, use 70-90°C hot water for continuous analysis, m (analysis hot water): m (resin) = 2-5:1, and sample the analysis solution for analysis.

[0012] It is further preferred that the mass concentration of the ethanol solution in step 1) is 50-75%.

[0013] It is further preferred that in step 1), the ethanol solution is heated to 40-70° C. and continuously injected into the adsorption column.

[0014] It is further preferred that the central temperature in step 2) is consistent with the feed temperature.

[0015] It is further preferred that the adsorption resin column in step 2) is filled with a resin having weak polar groups.

[0016] More preferably, the weak polar group specifically refers to a weak basic group; the weak basic group is a primary amine, secondary amine, tertiary amine and quaternary amine group.

[0017] More preferably, the resin in step 2) is in granular form with a particle size of 0.2 to 2 mm and a pore size of 100 to 1000 nm.

[0018] The preferred resin with weak polar groups in the present invention is a highly cross-linked, high specific surface area decolorizing resin with a cross-linking degree of >20% (relatively tight, strong and durable); a specific surface area of ​​>150m 2 / g.

[0019] According to the method for continuous decolorization in potassium sorbate production of the present invention, in step 4), the front-end analytical solution is an aqueous solution containing potassium sorbate and then sent to the acid precipitation process, and the acid precipitation is carried out to sorbic acid for recovery treatment, and the back-end analytical solution with a pH value less than 7 and a conductivity value less than 1000us / cm is mixed with the next batch of analytical hot water for analysis. (The front-end and the back-end are defined comprehensively based on the pH value and the conductivity value. As the analysis progresses, the potassium sorbate content in the analytical solution will decrease, and its pH value and conductivity will decrease.)

[0020] The invention adopts a novel resin to replace activated carbon to continuously decolorize a potassium sorbate solution, so as to obtain a colorless, clear and transparent potassium sorbate aqueous solution, and regenerates after decolorization reaches saturation analysis. After analysis, water vapor is used to wash and recover the adsorbed potassium sorbate. Compared with the activated carbon, the pretreated resin has improved adsorption efficiency of impurities, and the adsorption device is simplified. At the same time, after the saturated resin is recovered, the potassium sorbate can be reused, so the solid waste problem after adsorption is solved, and the production cost is reduced to a certain extent.

[0021] The present invention relates to a decolorization process for potassium sorbate production. A novel resin is used to replace activated carbon to decolorize a potassium sorbate solution. The resin preferably has a weak polar group and is a highly cross-linked, high specific surface area decolorization resin (cross-linking degree> 20% (resins with high cross-linking degree are polymerized more tightly, firmly and durable); the specific surface area is> 150m 2 / g); the decolorization process mainly involves pre-treating the new resin with hot ethanol to remove the inert components in the resin pores (the inert components refer to the inert components used to prepare the resin, such as toluene, benzene and other substances);), and then washing with hot water to remove the free inorganic groups (such as some metal groups) generated during the synthesis process; for example, the detached amino groups, and then passing a certain concentration of potassium sorbate solution into a filling column filled with the pre-treated new resin for continuous decolorization to obtain a colorless, clear, transparent potassium sorbate aqueous solution. After the decolorization reaches saturation, switch to the second filling column to realize the continuous decolorization process, and at the same time, analyze and regenerate the first filling column, and use water vapor to clean and recover the adsorbed potassium sorbate after analysis. The specific steps are as follows:

[0022] 1) The resin of this process uses a weak polar group resin. It is pretreated for the first use. A 50-75% mass concentration ethanol solution is used, heated to 40-70°C, and a certain flow rate (a certain flow rate is calculated based on the amount of ethanol solution loaded with the resin); it is continuously injected into the adsorption column and then continuously discharged, m (ethanol solution): m (resin) = 1-3:1, and the cleaning time is 3-10h; after cleaning, it is washed with hot water, the water temperature is 50-90°C, m (water): m (resin) = 1-5:1; the cleaning time is 4-8h, and the ethanol content in the water is <0.03%;

[0023] 2) The neutralized potassium sorbate aqueous solution is fed into the adsorption resin column at a certain flow rate (the certain flow rate is determined according to the actual volume of the decolorization column and the residence time of the neutralized solution); the concentration of the neutralized potassium sorbate aqueous solution is 38-60%, and the pH is 8.0-11; the feed temperature is 50-85° C., the residence time of the neutralized solution feed is 0.5-5 h, and the resin column is kept warm (the center temperature is consistent with the feed temperature);

[0024] 3) After decolorization, the transmittance of the potassium sorbate aqueous solution is increased from 80% to 85-95%, the transmittance of the finished potassium sorbate is 98.0-98.5%, and the decolorization yield is 99.0-99.5%;

[0025] 4) Continuously decolorize until the transmittance of the potassium sorbate aqueous solution is ≤85%, switch the feed to another decolorization column, adsorb the saturated resin column for analysis, use 70-90°C hot water for continuous analysis, m (analysis hot water): m (resin) = 2-5:1, sample and analyze the analysis liquid, the front stage analysis liquid contains potassium sorbate aqueous solution and then sent to the acid precipitation process, acid precipitation to sorbic acid for recovery, the back stage PH <7, conductivity ≤1000us / cm analysis liquid is mixed with the next batch of analysis hot water for analysis.

[0026] In the present invention, the tar is obtained by acid precipitation treatment of the analytical solution, the sorbic acid precipitated by the acid is reused, and the tar enters the acid precipitation liquid;

[0027] Beneficial Effects

[0028] 1) The use of new resin instead of activated carbon realizes the continuous decolorization process with large processing capacity, which can greatly reduce industrial production costs and improve product quality;

[0029] 2) The use of new resins instead of activated carbon solves the problem of activated carbon regeneration difficulties and reduces environmental pollution. It is a new decolorization process that is more environmentally friendly;

[0030] 3) The new resin has a simple analytical method and can recover potassium sorbate, reduce material loss, increase industrial benefits, and has certain economic value.

[0031] 4) After decolorization, the transmittance of the potassium sorbate aqueous solution is increased from 80% to 85-95%, the transmittance of the finished potassium sorbate is 98.0-98.5%, and the decolorization yield is 99.0-99.5%.

[0032] The present invention adopts resin to replace activated carbon, and combines process operation to realize the integration of adsorption and analysis. Conventional activated carbon treatment will introduce phosphate or sulfate ions, which have a certain impact on product quality (phosphoric acid or sulfuric acid is recycled to adjust pH in the activated carbon preparation process); the unforeseen advantage of using resin adsorption is to reduce the chloride ion content in the potassium sorbate solution. The chloride ion index is an important index of the finished potassium sorbate product. During the research process, we surprisingly found that the resin adsorbs chloride ions and sulfate ions while adsorbing colored groups. Therefore, by using resin adsorption, the inorganic ion content of the finished product is reduced, which is a beneficial effect that is difficult to achieve with activated carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of a continuous resin decolorization device for potassium sorbate neutralization liquid.

[0034] ①Potassium sorbate neutralization liquid tank, ②Potassium sorbate neutralization liquid feeding pump, ③1# resin column, ④2# resin column, ⑤Potassium sorbate decolorization liquid feeding pump, ⑥Analysis liquid feeding pump, ⑦Analysis hot water tank, ⑧Analysis hot water feeding pump.

[0035] Figure 2 This is the process flow chart of potassium sorbate continuous resin decolorization. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the embodiments. Those skilled in the art should understand that the embodiments are only used for illustration and do not constitute any limitation to the present invention.

[0037] Embodiment 1:

[0038] 1) The resin of this process uses a weak polar group resin. It is pretreated for the first use. A 50% mass concentration ethanol solution is used, heated to 40°C, continuously injected into the adsorption column at a certain flow rate, and then continuously discharged. m (ethanol solution): m (resin) = 1:1, and the cleaning time is 3h; after cleaning, it is washed with hot water, the water temperature is 50°C, m (water): m (resin) = 1:1, and the cleaning time is 4h, until the ethanol content in the water is <0.03%;

[0039] 2) The neutralized potassium sorbate aqueous solution continuously enters the adsorption resin column at a certain flow rate, wherein the concentration of the neutralized potassium sorbate aqueous solution is 38% and the pH is 8.0; the feed temperature is 50° C., the residence time of the neutralized liquid feed is 0.5 h, and the resin column is kept warm (the center temperature is consistent with the feed temperature);

[0040] 3) After decolorization, the transmittance of the potassium sorbate aqueous solution is increased from 80% to 85%, the transmittance of the finished potassium sorbate is 98.5%, and the decolorization yield is 99.0%;

[0041] 4) Continuously decolorize until the transmittance of the potassium sorbate aqueous solution is ≤85%, switch the feed to another decolorization column, adsorb the saturated resin column for analysis, use 70°C hot water for continuous analysis, m (analysis hot water): m (resin) = 2:1, sample and analyze the analysis liquid, the front stage analysis liquid contains potassium sorbate aqueous solution and then sent to the acid precipitation process, acid precipitation to sorbic acid for recovery, the back stage PH <7, conductivity ≤1000us / cm analysis liquid is mixed with the next batch of analysis hot water for analysis.

[0042] Embodiment 2:

[0043] 1) The resin of this process uses a weak polar group resin. It is pretreated for the first use. A 55% mass concentration ethanol solution is used, heated to 50°C, continuously injected into the adsorption column at a certain flow rate, and then continuously discharged. m (ethanol solution): m (resin) = 1.5: 1, and the cleaning time is 5h; after cleaning, it is washed with hot water, the water temperature is 60°C, m (water): m (resin) = 2: 1, and the cleaning time is 5h, until the ethanol content in the water is <0.03%;

[0044] 2) The neutralized potassium sorbate aqueous solution continuously enters the adsorption resin column at a certain flow rate, wherein the concentration of the neutralized potassium sorbate aqueous solution is 45% and the pH is 8.8; the feed temperature is 60° C., the residence time of the neutralized liquid feed is 1 hour, and the resin column is kept warm (the center temperature is consistent with the feed temperature);

[0045] 3) After decolorization, the transmittance of the potassium sorbate aqueous solution is increased from 80% to 90%, the transmittance of the finished potassium sorbate is 98.2%, and the decolorization yield is 99.1%;

[0046] 4) Continuously decolorize until the transmittance of the potassium sorbate aqueous solution is ≤85%, switch the feed to another decolorization column, adsorb the saturated resin column for analysis, use 75°C hot water for continuous analysis, m (analysis hot water): m (resin) = 2.8:1, sample and analyze the analysis liquid, the front stage analysis liquid contains potassium sorbate aqueous solution and then sent to the acid precipitation process, acid precipitation to sorbic acid for recovery, the back stage PH <7, conductivity ≤1000us / cm analysis liquid is mixed with the next batch of analysis hot water for analysis.

[0047] Embodiment 3:

[0048] 1) The resin of this process uses a weak polar group resin. It is pretreated for the first use. A 60% mass concentration ethanol solution is used, heated to 60°C, continuously injected into the adsorption column at a certain flow rate, and then continuously discharged. m (ethanol solution): m (resin) = 2:1, and the cleaning time is 7h; after cleaning, it is washed with hot water, the water temperature is 70°C, m (water): m (resin) = 3:1, and the cleaning time is 7h, until the ethanol content in the water is <0.03%;

[0049] 2) The neutralized potassium sorbate aqueous solution continuously enters the adsorption resin column at a certain flow rate, wherein the neutralized potassium sorbate aqueous solution has a concentration of 50% and a pH of 9.5; the feed temperature is 70° C., the residence time of the neutralized solution feed is 3 hours, and the resin column is kept warm (the center temperature is consistent with the feed temperature);

[0050] 3) After decolorization, the transmittance of the potassium sorbate aqueous solution is increased from 80% to 95%, the transmittance of the finished potassium sorbate is 98.5%, and the decolorization yield is 99.3%;

[0051] 4) Continuously decolorize until the transmittance of the potassium sorbate aqueous solution is ≤85%, switch the feed to another decolorization column, adsorb the saturated resin column for analysis, use 85°C hot water for continuous analysis, m (analysis hot water): m (resin) = 4:1, sample and analyze the analysis liquid, the front stage analysis liquid contains potassium sorbate aqueous solution and then sent to the acid precipitation process, acid precipitation to sorbic acid for recovery, the back stage PH <7, conductivity ≤1000us / cm analysis liquid is mixed with the next batch of analysis hot water for analysis.

[0052] Embodiment 4:

[0053] 1) The resin of this process uses a weak polar group resin. It is pretreated for the first use. A 75% mass concentration ethanol solution is used, heated to 70°C, continuously injected into the adsorption column at a certain flow rate, and then continuously discharged. m (ethanol solution): m (resin) = 3:1, and the cleaning time is 10h; after cleaning, it is washed with hot water, the water temperature is 90°C, m (water): m (resin) = 5:1, and the cleaning time is 8h, until the ethanol content in the water is <0.03%;

[0054] 2) The neutralized potassium sorbate aqueous solution continuously enters the adsorption resin column at a certain flow rate, wherein the concentration of the neutralized potassium sorbate aqueous solution is 60% and the pH is 11; the feed temperature is 85° C., the residence time of the neutralized solution feed is 5 hours, and the resin column is kept warm (the center temperature is consistent with the feed temperature);

[0055] 3) After decolorization, the transmittance of the potassium sorbate aqueous solution is increased from 80% to 94%, the transmittance of the finished potassium sorbate is 98.3%, and the decolorization yield is 99.5%;

[0056] 4) Continuously decolorize until the transmittance of the potassium sorbate aqueous solution is ≤85%, switch the feed to another decolorization column, adsorb the saturated resin column for analysis, use 90°C hot water for continuous analysis, m (analysis hot water): m (resin) = 5:1, sample and analyze the analysis liquid, the front stage analysis liquid contains potassium sorbate aqueous solution and then sent to the acid precipitation process, acid precipitation to sorbic acid for recovery, the back stage PH <7, conductivity ≤1000us / cm analysis liquid is mixed with the next batch of analysis hot water for analysis.

[0057] The chloride ion content of the potassium sorbate product is compared with the product data of the prior art as follows:

[0058] category Chloride ion content of sorbic acid finished product / % Existing process 0.012 Process Example 1 of the present invention 0.008 Process Example 2 of the present invention 0.008 Process Example 3 of the present invention 0.007 Process Example 4 of the present invention 0.008

[0059] The present invention uses a new type of resin instead of activated carbon to realize a continuous decolorization process with a large processing capacity, which can significantly reduce industrial production costs and improve product quality. It can be enlarged based on the data of small-scale research, as shown in the following table;

[0060] category Decolorizing liquid processing capacity Activated carbon column (1L filling volume) 300ml / h Resin column (1L filling volume) 550ml / h

Claims

1. A method for continuous decolorization in potassium sorbate production, characterized in that: The steps include: 1) Pretreatment of the adsorption resin column, using ethanol solution to continuously inject into the adsorption column and then continuously discharge, m (ethanol solution): m (resin) = 1-3: 1, the cleaning time is 3-10 hours; after cleaning, it is washed with hot water, the water temperature is 50-90°C, m (water): m (resin) = 1-5: 1, the cleaning time is 4-8 hours, and the ethanol content in the water is <0.03%; 2) The neutralized potassium sorbate aqueous solution continuously enters the adsorption resin column, wherein the concentration of the neutralized potassium sorbate aqueous solution is 38-60%, and the pH is 8.0-11; the feed temperature is 50-85° C., the residence time of the neutralized liquid feed is 0.5-5 h, and the resin column is kept warm; the adsorption resin column is filled with a weak polar group resin; 3) After decolorization, the transmittance of the potassium sorbate aqueous solution is increased from 80% to 85-95%, the transmittance of the finished potassium sorbate is 98.0-98.5%, and the decolorization yield is 99.0-99.5%; 4) Continuously decolorize until the transmittance of the potassium sorbate aqueous solution is ≤85%, switch the feed to another decolorization column, adsorb the saturated resin column for analysis, use 70-90°C hot water for continuous analysis, m (analysis hot water): m (resin) = 2-5:1, and sample the analysis solution for analysis.

2. A method for continuous decolorization in the production of potassium sorbate according to claim 1, characterized in that: The mass concentration of the ethanol solution in step 1) is 50-75%.

3. A method for continuous decolorization in the production of potassium sorbate according to claim 1, characterized in that: In step 1), the ethanol solution is heated to 40-70° C. and continuously injected into the adsorption column.

4. A method for continuous decolorization in the production of potassium sorbate according to claim 1, characterized in that: In step 2), the center temperature is consistent with the feed temperature.

5. A method for continuous decolorization in the production of potassium sorbate according to claim 1, characterized in that: The weak polar group specifically refers to a weak basic group; the weak basic group is a primary amine, a secondary amine, a tertiary amine and a quaternary amine group.

6. A method for continuous decolorization in the production of potassium sorbate according to claim 1, characterized in that: The resin in step 2) is in granular form with a particle size of 0.2 to 2 mm and a pore size of 100 to 1000 nm.

7. A method for continuous decolorization in the production of potassium sorbate according to claim 1, characterized in that: In step 4), the analytical solution in the front stage is an aqueous solution containing potassium sorbate, which is then sent to the acid precipitation process, and the sorbic acid is recovered and processed. The analytical solution in the back stage with pH <7 and conductivity ≤1000us / cm is mixed with the next batch of analytical hot water for analysis.

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