A treatment method and system for pentanal condensation waste lye

Abstract

The application provides a treatment method and a treatment system for pentanal condensation waste lye, and the treatment method comprises the following steps: step 1, acidifying the pentanal condensation waste lye to obtain organic phase and aqueous phase by layering; step 2, concentrating the aqueous phase to obtain concentrated water; and step 3, feeding the concentrated water into a five-chamber bipolar membrane electrodialysis device to obtain an organic acid solution and a NaOH solution; wherein the five-chamber bipolar membrane electrodialysis device is sequentially provided with an anode electrolysis chamber, a dilute acid isolation chamber, an acid chamber, a center isolation chamber, an alkali chamber, a dilute alkali isolation chamber and a cathode electrolysis chamber, the concentrated water is fed into the center isolation chamber, under the action of a direct current electric field, Na + into the alkali chamber and combines with OH ‑ to generate NaOH, carboxylate ions ionized from the concentrated water enter the acid chamber and combine with H + to generate organic acid, the dilute organic acid in the dilute acid isolation chamber is used as the circulating liquid of the acid chamber, and the dilute NaOH solution in the dilute alkali isolation chamber is used as the circulating liquid of the alkali chamber.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical waste lye treatment, and particularly relates to a treatment method and system for waste lye from pentanal condensation. BACKGROUND

[0002] Pentanal condensation is an intermediate unit in the industrial production of 2-propylheptanol (2-PH), in which two moles of n-pentanal generate one mole of decenyl aldehyde and one mole of water under the condition of catalyst NaOH. In addition, Cannizzaro Reaction also occurs under this condition, and the reaction formula is as follows:

[0003] 2CH3CH2CH2CH2CHO + NaOH →

[0004] CH3CH2CH2CH2COONa + CH3CH2CH2CH2CH2OH

[0005] Due to the generation of water in the condensation process, and the consumption of NaOH in Cannizzaro Reaction, the alkali concentration of the device will gradually decrease. In order to maintain a constant alkali concentration, a part of the lye will be discharged and a part of fresh lye will be added. This part of lye discharged is called waste lye. The alkali content of the waste lye is 1-2%, and the organic matter composition is complex, mainly including pentanal, pentanol, pentanoic acid, decenyl aldehyde, etc. The chemical oxygen demand (COD Cr ) is about 60000-110000 mg / L.

[0006] At present, the waste lye of pentanal condensation device in China is diluted and sent to the sewage plant, which further increases the load of the sewage treatment system.

[0007] Chinese patent CN108128982A discloses a treatment method for waste lye from pentanal condensation, which comprises the following steps: (1) the waste water enters the concentration package equipment, the concentrated liquid obtained by the concentration package equipment is cooled by a cooler and then enters an acidification tank, and the water concentrated by the concentration package equipment enters a biochemical treatment plant for biochemical treatment; (2) the concentrated liquid at the outlet of the acidification tank enters a chromatograph to obtain an organic phase and an aqueous phase; (3) the organic phase enters a rectifying column, pentanoic acid is obtained at the top of the rectifying column, and the heavy components in the kettle of the rectifying column enter a incinerator, and the aqueous phase enters an evaporation crystallizer to obtain water and solid salt. The invention solves the problem of large load of the sewage plant in the waste water treatment process, and also recovers organic acid. However, the method firstly evaporates and concentrates the waste lye, and the evaporation of water will take away part of the organic matter, and the waste water with low COD Cr still needs to be treated by the sewage plant, and secondly, the purity of the solid salt obtained is low, and the utilization value is not great.

[0008] Chinese patent CN104071940B discloses a treatment method of butanol octanol waste lye, which first adopts inorganic acid to acidify the waste lye, then carries out osmotic gasification membrane evaporation concentration treatment on the acidified liquid, or carries out osmotic gasification membrane evaporation on the acidified liquid after removing oil, and recovers inorganic acid sodium salt by cooling crystallization after oil-water separation of the evaporation concentrated liquid, returns the crystallization kettle liquid to the acidification reactor for recycling, carries out adsorption treatment on the evaporation condensed liquid, returns part of the adsorbed water to the condensation device for preparing lye, and discharges part into a sewage plant. The method realizes resource recycling of organic matter, can recover inorganic salt generated in the acidification process as by-product, and can use the treated water to prepare lye instead of fresh desalted water, but the inorganic salt obtained by the method has low purity and little value, and low-COD wastewater is still generated. Cr waste water.

[0009] The treatment of pentanal condensation waste lye still needs to be researched in the art. SUMMARY

[0010] The main purpose of the present application is to provide a treatment method and system of pentanal condensation waste lye, so as to overcome the problem that the product obtained by treating pentanal condensation waste lye in the prior art has little value and low-COD wastewater is still generated.

[0011] In order to achieve the above purpose, the present application provides a treatment method of pentanal condensation waste lye, comprising the following steps:

[0012] Step 1, acidifying the pentanal condensation waste lye to obtain organic phase and aqueous phase by layering;

[0013] Step 2, concentrating the aqueous phase to obtain concentrated water;

[0014] Step 3, feeding the concentrated water into a five-chamber bipolar membrane electrodialysis device to obtain organic acid solution and NaOH solution;

[0015] The five-chamber bipolar membrane electrodialysis device is sequentially provided with an anode electrolysis chamber, a dilute acid isolation chamber, an acid chamber, a center isolation chamber, an alkali chamber, a dilute alkali isolation chamber and a cathode electrolysis chamber, the concentrated water is fed into the center isolation chamber, under the action of a direct current electric field, Na + into the alkali chamber to combine with OH - to generate NaOH, and the carboxylate ions ionized from the concentrated water into the acid chamber to combine with H + to generate organic acid, the dilute organic acid in the dilute acid isolation chamber is used as the circulating liquid of the acid chamber, and the dilute NaOH solution in the dilute alkali isolation chamber is used as the circulating liquid of the alkali chamber.

[0016] The pentanal condensation waste lye treatment method, wherein the anode electrolysis chamber and the dilute acid isolation chamber are separated by a cation exchange membrane, and the cathode electrolysis chamber and the dilute alkali isolation chamber are separated by an anion exchange membrane.

[0017] The pentanal condensation waste lye treatment method, wherein the dilute acid isolation chamber and the acid chamber, and the dilute alkali isolation chamber and the alkali chamber are separated by bipolar membranes, the acid chamber and the center isolation chamber are separated by an anion exchange membrane, and the alkali chamber and the center isolation chamber are separated by a cation exchange membrane.

[0018] The pentanal condensation waste lye treatment method, wherein the acid used for acidification treatment is pentanoic acid; in the acidification treatment, the pH value of the pentanal condensation waste lye is adjusted to 0-6, and the temperature is 25-60℃.

[0019] The pentanal condensation waste lye treatment method, wherein the separation method is centrifugation, the centrifugation speed is 500-3000 rpm, and the centrifugation time is 1-10 min; the organic phase obtained by separation is used as a byproduct, or the organic phase is transported to a rectifying tower for separation, and the obtained organic acid is recycled for acidification treatment.

[0020] The pentanal condensation waste lye treatment method, wherein the number of plates of the rectifying tower is 30-60, the feed plate is 16-26, the reflux ratio is 1.9-2.9, the tower pressure is 5-50 kpa, the tower top temperature is 40-60℃, and the tower bottom temperature is 120-130℃.

[0021] The pentanal condensation waste lye treatment method, wherein when the water phase is concentrated, the obtained distilled water is recycled for preparation of the lye used in the pentanal condensation process.

[0022] The pentanal condensation waste lye treatment method, wherein the concentration of sodium carboxylate in the concentrated water is 2-3 mol / L.

[0023] To achieve the above purpose, the application further provides a pentanal condensation waste lye treatment system, comprising:

[0024] An acidification device for acidification treatment of pentanal condensation waste lye;

[0025] A separation device in communication with the acidification device to separate the acidification-treated pentanal condensation waste lye to obtain an organic phase and a water phase;

[0026] A concentration device in communication with the separation device to concentrate the water phase to obtain concentrated water;

[0027] A five-chamber bipolar membrane electrodialysis device is in communication with the concentration device, and the five-chamber bipolar membrane electrodialysis device is sequentially provided with an anode electrolysis chamber, a dilute acid isolation chamber, an acid chamber, a center isolation chamber, a base, a dilute alkali isolation chamber, and a cathode electrolysis chamber. + Enter the alkali chamber and OH - Combine to generate NaOH, and the carboxylate ions ionized from the concentrated water enter the acid chamber and H + Combine to generate organic acid, and the dilute organic acid in the dilute acid isolation chamber is used as the circulating liquid of the acid chamber, and the dilute NaOH solution in the dilute alkali isolation chamber is used as the circulating liquid of the alkali chamber.

[0028] The pentanal condensation waste lye treatment system provided by the application, wherein the anode electrolysis chamber and the dilute acid isolation chamber are separated by a cation exchange membrane, the cathode electrolysis chamber and the dilute alkali isolation chamber are separated by an anion exchange membrane, the dilute acid isolation chamber and the acid chamber are separated by a bipolar membrane, the dilute alkali isolation chamber and the alkali chamber are separated by a bipolar membrane, the acid chamber and the center isolation chamber are separated by an anion exchange membrane, and the alkali chamber and the center isolation chamber are separated by a cation exchange membrane.

[0029] The application has the following beneficial effects:

[0030] The five-chamber bipolar membrane electrodialysis device is provided with a dilute alkali isolation chamber and a dilute acid isolation chamber, and the dilute alkali and the dilute acid generated by the device are used as the circulating liquid of the alkali chamber and the acid chamber respectively, so that the recovery rate and purity of the alkali and the acid in the recovered alkali chamber and acid chamber can be further improved, and the value of the obtained product can be improved.

[0031] Further, the dilute alkali isolation chamber and the dilute acid isolation chamber can protect the electrode materials of the anode electrolysis chamber and the cathode electrolysis chamber, so that the organic acid root ions do not contact the anode material, the Na + Contact the cathode material, and the electrode materials are not damaged. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The figure is a structural schematic diagram of the five-chamber bipolar membrane electrodialysis device of an embodiment of the application.

[0033] Figure 2 The figure is a schematic diagram of the pentanal condensation waste lye treatment system of an embodiment of the application.

[0034] In the figure, the reference signs are as follows:

[0035] 1 anode electrolysis chamber

[0036] 2 dilute acid isolation chamber

[0037] 3 acid chamber

[0038] 4 central compartment

[0039] 5 base compartment

[0040] 6 dilute base compartment

[0041] 7 cathode electrolysis compartment

[0042] 11 acidification device

[0043] 12 separation device

[0044] 13 rectification column

[0045] 14 concentration device

[0046] 15 condenser

[0047] 16 five-compartment bipolar membrane electrodialysis device

[0048] 17 NaOH solution

[0049] 18 organic acid solution

[0050] 19 pentanal condensation waste base solution

[0051] 20 n-pentanoic acid

[0052] 21 organic phase

[0053] 22 n-pentanoic acid

[0054] 23 heavy components

[0055] 24 distilled water

[0056] 25 aqueous phase

[0057] A cation exchange membrane

[0058] B bipolar membrane

[0059] C anion exchange membrane

[0060] D cation exchange membrane

[0061] E bipolar membrane

[0062] F anion exchange membrane DETAILED DESCRIPTION

[0063] The technical solution of the present application is described in detail below. The following embodiments are implemented on the basis of the technical solution of the present application, and a detailed implementation process is given. However, the protection scope of the present application is not limited to the following embodiments. The structure or experimental method not specified in the following embodiments is usually carried out according to the conventional conditions.

[0064] The application provides a treatment method of pentanal condensation waste lye, which generally contains 1-2wt% NaOH and also contains organic matters such as n-pentanal, n-pentanol, sodium valerate, decenal and n-valeric acid.

[0065] The treatment method of pentanal condensation waste lye comprises the following steps:

[0066] Step 1, the pentanal condensation waste lye is subjected to acidification treatment to obtain organic phase and water phase by layering;

[0067] Step 2, the water phase is concentrated to obtain concentrated water;

[0068] Step 3, the concentrated water is transported to a five-chamber bipolar membrane electrodialysis device to obtain organic acid solution and NaOH solution;

[0069] The five-chamber bipolar membrane electrodialysis device is sequentially provided with an anode electrolysis chamber, a dilute acid isolation chamber, an acid chamber, a center isolation chamber, an alkali chamber, a dilute alkali isolation chamber and a cathode electrolysis chamber, the concentrated water is transported to the center isolation chamber, under the action of a direct current electric field, Na + OH- in the concentrated water is combined to generate NaOH, and carboxylate ions in the concentrated water are combined with H - + in the acid chamber to generate organic acid, the dilute organic acid in the dilute acid isolation chamber is used as the circulating liquid of the acid chamber, and the dilute NaOH solution in the dilute alkali isolation chamber is used as the circulating liquid of the alkali chamber. +

[0070] The five-chamber bipolar membrane electrodialysis device is provided with a dilute alkali isolation chamber and a dilute acid isolation chamber, and the dilute alkali and the dilute acid generated by the device are used as the circulating liquids of the alkali chamber and the acid chamber respectively, so that the purity of the alkali and the acid recovered from the alkali chamber and the acid chamber can be further improved, and the value of the obtained product can be improved.

[0071] ​In step 1 of the present application, the pentanal condensation waste lye is first acidified, i.e. mixed with an acid. In one embodiment, the acid used in the present application is an organic acid, further, a carboxylic acid with the same carbon number as the raw material aldehyde, and further, a straight-chain carboxylic acid, such as pentanoic acid. The organic acid is used to acidify the waste lye in the present application, and the weak acid can reduce the corrosion of the equipment, and the organic matter in the waste lye is recovered as a byproduct or the organic acid in the organic matter is separated and recycled. The amount of acid used is to adjust the pH of the pentanal condensation waste lye to 0-6, preferably 2.5-3.5, for example 3, and the acidification temperature is set to 25-60°C, and the optimal acidification temperature is 35-45°C, for example 40°C. After acidification, carboxylate is generated in the pentanal condensation waste lye, and due to the salting-out effect, the organic matter is precipitated from water, and the oil and water are separated, for example by centrifugation, to obtain an organic phase and an aqueous phase. In another embodiment, the centrifugation time is 1-10 min, preferably 1-5 min, for example 4 min, and the rotation speed is 500-3000 rpm, preferably 1000-2000 rpm, for example 1500 rpm.

[0072] The organic phase can be used as a byproduct, or can be transported to a rectification tower for separation, and the separated organic acid is recycled for the above acidification treatment. In one embodiment, the number of plates of the rectification tower is 30-60, the feed plate is 16-26, the reflux ratio is 1.9-2.9, the tower pressure is 5-50 kPa, the top temperature is 40-60°C, and the bottom temperature is 120-130°C; for example, the number of plates is 30, the feed plate is 16, the reflux ratio is 1.9, the tower pressure is 5 kPa, the top temperature is 40°C, and the bottom temperature is 120°C.

[0073] The aqueous phase after separation contains almost no alcohol, aldehyde and heavy components in the pentanal condensation waste lye, and the main component is carboxylate. The aqueous phase is concentrated, for example at a temperature of 100-120°C, and further for example at 106°C. Concentration increases the concentration of carboxylate, and concentrated water is obtained, and the water can be recycled for preparing the lye used in the pentanal condensation process. In one embodiment, the concentration of sodium carboxylate in the concentrated water is 2-3 mol / L.

[0074] Then, the concentrated water is transported to a five-chamber bipolar membrane electrodialysis device to obtain an organic acid solution and a NaOH solution.

[0075] The five-chamber bipolar membrane electrodialysis device of the present application is as shown in Figure 1As shown, the anode electrolysis chamber 1, the dilute acid isolation chamber 2, the acid chamber 3, the center isolation chamber 4, the alkali chamber 5, the dilute alkali isolation chamber 6 and the cathode electrolysis chamber 7 are sequentially arranged. The anode electrolysis chamber 1 is adjacent to the dilute acid isolation chamber 2, and the two are separated by a cation exchange membrane A; the dilute acid isolation chamber 2 is adjacent to the acid chamber 3, and the two are separated by a bipolar membrane B; the acid chamber 3 is adjacent to the center isolation chamber 4, and the two are separated by an anion exchange membrane C; the center isolation chamber 4 is adjacent to the alkali chamber 5, and the two are separated by a cation exchange membrane D; the alkali chamber 5 is adjacent to the dilute alkali isolation chamber 6, and the two are separated by a bipolar membrane E; the dilute alkali isolation chamber 6 is adjacent to the cathode electrolysis chamber 7, and the two are separated by an anion exchange membrane F.

[0076] The present application can protect the electrode materials of the anode electrolysis chamber and the cathode electrolysis chamber by arranging the dilute alkali isolation chamber and the dilute acid isolation chamber, so as to avoid the contact of the organic acid with the anode material, the contact of Na + with the cathode material, and further avoid the damage of the electrode materials.

[0077] In detail, the anode electrolysis chamber 1 and the cathode electrolysis chamber 7 respectively use sodium sulfate as the electrolyte, the sodium sulfate electrolyte can be recycled, and the dilute acid isolation chamber 2 and the dilute alkali isolation chamber 6 use sodium sulfate as the auxiliary chamber. The concentrated water enters the center isolation chamber 4, under the action of the electric field, the organic acid root such as valeric acid root enters the acid chamber 3 through the anion exchange membrane C, Na + enters the alkali chamber 5 through the cation exchange membrane D; under the action of the current electric field, the bipolar membranes B and E hydrolyze to generate H + and OH - , the organic acid root and H + generate organic acid in the acid chamber 3, Na + and OH - generate NaOH in the alkali chamber 5. The dilute valeric acid sodium solution flowing out of the center isolation chamber 4 is recycled after supplementing valeric acid to increase the solution concentration.

[0078] In order to avoid that a small amount of organic acid root ions in the acid chamber 3 enter the anode electrolysis chamber 1 through the bipolar membrane B by using the concentration difference, the present application specially arranges the dilute acid isolation chamber 2 and the cation exchange membrane A, so as to avoid that the organic acid root ions adhere to the anode plate, lose electrons to generate CO2 and other acidic gases, and further avoid the damage of the anode plate. Similarly, in order to avoid that a small amount of Na + in the alkali chamber 5 enter the cathode electrolysis chamber 7 through the bipolar membrane E by using the concentration difference, the present application specially arranges the dilute alkali isolation chamber 6 and the anion exchange membrane F, so as to avoid that Na + adhere to the cathode plate, further gain electrons to generate metallic sodium adhering to the surface of the cathode plate, and avoid the damage of the cathode plate.

[0079] A small amount of organic acid root ions in the acid chamber 3 of the present application will enter the dilute acid isolation chamber 2 through the bipolar membrane B by using the concentration difference, and H+ The cations will pass through the cation exchange membrane A into the dilute acid isolation chamber 2, and according to the principle of electric neutrality, dilute organic acid such as dilute n-valeric acid will flow out of the dilute acid isolation chamber 2, which can be used as the circulating liquid of the acid chamber 3 to improve the concentration and purity of the organic acid such as n-valeric acid flowing out of the acid chamber 3. Similarly, a small amount of Na + The ions will pass through the bipolar membrane E into the dilute base isolation chamber 6 using the concentration difference, and the OH - The anions will pass through the anion exchange membrane F into the dilute base isolation chamber 6, and according to the principle of electric neutrality, dilute NaOH solution will flow out of the dilute base isolation chamber 6, which can be used as the circulating liquid of the base chamber 5 to improve the concentration and purity of the NaOH flowing out of the base chamber 5.

[0080] In a specific embodiment, the membrane stack size of the five-chamber type bipolar membrane electrodialysis device of the present application is 90*210mm 2 , and the membrane performance parameters are shown in Table 1 below, but the present application is not limited thereto, and can be selected as needed.

[0081] Table 1

[0082]

[0083] Therefore, the present application provides a treatment method for pentanal condensation waste lye, which first passes the pentanal condensation waste lye into an acidification system, recovers the organic phase in the upper layer as a byproduct or sends it into a rectification tower to separate the organic acid as acid for acidification; then the water phase in the lower layer is evaporated and concentrated in a concentration system, and the water vapor condensate evaporated is used for the preparation of lye; the concentrated water phase is introduced into an improved five-chamber type bipolar membrane electrodialysis system to obtain high-concentration NaOH in the base chamber and high-concentration organic acid in the acid chamber.

[0084] The present application also provides a treatment system for pentanal condensation waste lye, as shown in the figure, which comprises: Figure 2

[0085] An acidification device 11 is used for acidification treatment of the pentanal condensation waste lye 19;

[0086] A separation device 12 is in communication with the acidification device 11 to perform delamination treatment on the pentanal condensation waste lye after acidification treatment, to obtain an organic phase 21 and a water phase 25;

[0087] A concentration device 14 is in communication with the separation device 12 to concentrate the water phase 25 to obtain concentrated water and water vapor 24;

[0088] A five-chamber type bipolar membrane electrodialysis device 16 is in communication with the concentration device 14 to treat the concentrated water to obtain an organic acid solution 18 and a NaOH solution 17.

[0089] ​The acidification device 11, the separation device 12 and the concentration device 14 are not particularly limited in the present application, and the devices in the art can be used as long as the corresponding functions described above can be achieved. The structure of the five-chamber bipolar membrane electrodialysis device 16 has been described in detail above, and will not be repeated here.

[0090] In an embodiment, the acid used for the acidification treatment is n-pentanoic acid 20, and the n-pentanoic acid 20 is transported to the acidification device 11 together with the waste caustic solution 19 condensed from the pentanal, and the acidification treatment is carried out under stirring.

[0091] In an embodiment, the organic phase 21 can be directly discharged from the system as a byproduct, or can be transported to the rectifying tower 13 for separation, and the organic acid 22 obtained by the separation is recycled for the acidification treatment, and the heavy component 23 obtained is discharged from the system.

[0092] In an embodiment, the concentrated water can be cooled by the condenser 15 and then transported to the five-chamber bipolar membrane electrodialysis device 16.

[0093] The technical solutions of the present application will be further described below through specific examples. The waste caustic solution condensed from pentanal is from Daqing Chemical Research Center of China Petroleum Natural Gas Co., Ltd., and the alkali concentration is 1.6-1.86 wt%, the COD Cr is 60000-110000 mg / L.

[0094] Evaluation and analysis method:

[0095] (1) The determination of COD selects potassium dichromate method.

[0096] (2) The determination of the amount of recovered acid and alkali adopts acid-base titration method.

[0097] Example 1

[0098] Take 2L of waste caustic solution condensed from pentanal (NaOH content is 1.8g / 100ml, sodium valerate is 8.6g / 100ml, pentanal is 0.2g / 100ml, pentanol is 0.2g / 100ml, decenyl aldehyde is 0.15g / 100ml), and the COD Cr concentration is 11652mg / L, n-pentanoic acid is used for the acidification treatment of the waste caustic solution, the pH is adjusted to 3, the acidification temperature is 45-60 degrees Celsius, the centrifugation time is 4min, the rotation speed is 1500r / min, the oil and water are separated, 39ml of oil phase is recovered as a byproduct, the lower water phase is 1.96L, and the COD of the clear water phase is measured to be 8250mg / L. Then, the water phase is evaporated and concentrated, the temperature is set to 106℃, the concentration is concentrated to 2mol / L of carboxylate, the five-chamber bipolar membrane electrodialysis device of the present application is used for the electrodialysis of the concentrated solution, the current density is 30mA / cm 2The concentrated sodium pentanoate is converted into NaOH and n-pentanoic acid, the dilute acid and dilute alkali flowing out of the dilute acid isolation chamber and the dilute alkali isolation chamber are returned to the acid chamber and the alkali chamber as circulating liquid, the recovered NaOH solution is 1.4 L, the mass concentration is 5.96 g / 100 ml, the NaOH recovery rate is 91.2%, the recovered n-pentanoic acid solution is 0.8 L, the concentration is 32.66 g / 100 ml, and the n-pentanoic acid recovery rate is 92.1%.

[0099] Example 2

[0100] Take 2 L of pentanal condensation waste alkali solution (NaOH content is 1.8 g / 100 ml, sodium pentanoate is 8.6 g / 100 ml, pentanal is 0.2 g / 100 ml, amyl alcohol is 0.2 g / 100 ml, and decenyl aldehyde is 0.15 g / 100 ml), COD Cr The waste alkali solution is acidified by n-pentanoic acid, the pH is adjusted to 3, the acidification temperature is 45-60 degrees Celsius, the centrifugal time is 4 min, the rotating speed is 1500 revolutions per minute, the oil and water are separated, 39 ml of oil phase is recovered as by-product, the lower water phase is 1.96 L, and the COD of the clear water phase is 8250 mg / L. Then, the water phase is evaporated and concentrated, the temperature is set to 106 degrees Celsius, the concentration is concentrated to 2.2 mol / L, the concentrated solution is subjected to electrodialysis by using the five-chamber bipolar membrane electrodialysis device, the current density is 30 mA / cm 2 The concentrated sodium pentanoate is converted into NaOH and n-pentanoic acid, the dilute acid and dilute alkali flowing out of the dilute acid isolation chamber and the dilute alkali isolation chamber are returned to the acid chamber and the alkali chamber as circulating liquid, the recovered NaOH solution is 1.4 L, the mass concentration is 5.96 g / 100 ml, the NaOH recovery rate is 91.2%, the recovered n-pentanoic acid solution is 0.8 L, the mass concentration is 32.66 g / 100 ml, and the n-pentanoic acid recovery rate is 92.1%.

[0101] Example 3

[0102] Take 2 L of pentanal condensation waste alkali solution (NaOH content is 1.8 g / 100 ml, sodium pentanoate is 8.6 g / 100 ml, pentanal is 0.2 g / 100 ml, amyl alcohol is 0.2 g / 100 ml, and decenyl aldehyde is 0.15 g / 100 ml), COD CrThe waste lye with a concentration of 11652 mg / L is acidified by using n-valeric acid, the pH is adjusted to 3, the acidification temperature is 45-60 degrees Celsius, the centrifugal time is 4 minutes, the rotating speed is 1500 revolutions per minute, the oil and water are separated, 39 ml of oil phase is recovered as by-product, 1.96 L of lower water phase is obtained, and the COD of the clear water phase is 8250 mg / L. Then, the water phase is evaporated and concentrated, the temperature is set to 106 degrees Celsius, the concentration of the carboxylate is 2.5 mol / L, the concentrated solution is subjected to electrodialysis by using the five-chamber bipolar membrane electrodialysis device, the current density is 30 mA / cm 2 The concentrated solution of sodium valerate is converted into NaOH and n-valeric acid, the dilute acid and dilute alkali flowing out of the dilute acid isolation chamber and the dilute alkali isolation chamber are returned to the acid chamber and the alkali chamber as circulating liquid, 1.38 L of NaOH solution is recovered, the mass concentration is 6.06 g / 100 ml, the NaOH recovery rate is 91.5%, 0.82 L of n-valeric acid solution is recovered, the mass concentration is 32.17 g / 100 ml, and the n-valeric acid recovery rate is 92.8%.

[0103] Example 4

[0104] 2 L of waste lye of valeraldehyde condensation (the NaOH content is 1.8 g / 100 ml, the sodium valerate is 8.6 g / 100 ml, the valeraldehyde is 0.2 g / 100 ml, the amyl alcohol is 0.2 g / 100 ml, and the decenal is 0.15 g / 100 ml) is taken, the COD Cr The waste lye with a concentration of 11652 mg / L is acidified by using n-valeric acid, the pH is adjusted to 3, the acidification temperature is 45-60 degrees Celsius, the centrifugal time is 4 minutes, the rotating speed is 1500 revolutions per minute, the oil and water are separated, 39 ml of oil phase is recovered as by-product, 1.96 L of lower water phase is obtained, and the COD of the clear water phase is 8250 mg / L. Then, the water phase is evaporated and concentrated, the temperature is set to 106 degrees Celsius, the concentration of the carboxylate is 2.5 mol / L, the concentrated solution is subjected to electrodialysis by using the five-chamber bipolar membrane electrodialysis device, the current density is 40 mA / cm 2 The concentrated solution of sodium valerate is converted into NaOH and n-valeric acid, the dilute acid and dilute alkali flowing out of the dilute acid isolation chamber and the dilute alkali isolation chamber are returned to the acid chamber and the alkali chamber as circulating liquid, 1.42 L of NaOH solution is recovered, the mass concentration is 5.89 g / 100 ml, the NaOH recovery rate is 91.5%, 0.84 L of n-valeric acid solution is recovered, the mass concentration is 31.3 g / 100 ml, and the n-valeric acid recovery rate is 92.6%.

[0105] Comparative Example 1

[0106] Take 2L pentanal condensation waste lye (NaOH content is 1.8g / 100ml, sodium pentanoate 8.6g / 100ml, pentanal 0.2g / 100ml, amyl alcohol 0.2g / 100ml, decenyl aldehyde 0.15g / 100ml), COD Cr The concentration is 11652mg / L, the waste lye is acidified by using n-valeric acid, the pH is adjusted to 3, the acidification temperature is 45-60 degrees Celsius, the centrifugal time is 4min, the rotating speed is 1500r / min, the oil and water are layered, the oil phase is recovered 39ml, as by-product, the lower water phase is 1.96L, the clear water phase COD is measured as 8250mg / L. Then the water phase is evaporated and concentrated, the temperature is set as 106℃, the concentration is set as 2.5mol / L, the concentrated liquid is subjected to electrodialysis by using three-chamber bipolar membrane electrodialysis device (i.e. without setting the five-chamber bipolar membrane electrodialysis device of the application, the remaining structure is similar to the five-chamber bipolar membrane electrodialysis device of the application), the current density is 40mA / cm 2 The concentrated liquid sodium valerate is converted into NaOH and n-valeric acid, the recovered NaOH solution is 1.4L, the mass concentration is 5.66g / 100ml, the NaOH recovery rate is 86.7%, the recovered n-valeric acid solution is 0.86L, the concentration is 27.81g / 100ml, the n-valeric acid recovery rate is 84.3%.

[0107] Of course, the present application can have other various embodiments, those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

Claims

1. A method for treating a pentanal condensation spent caustic solution, characterized by, It comprises the following steps: Step 1, the pentanal condensation waste lye is acidized to obtain organic phase and water phase by layering; Step 2, the water phase is concentrated to obtain concentrated water; Step 3, the concentrated water is transported to a five-chamber bipolar membrane electrodialysis device to obtain organic acid solution and NaOH solution; The five-chamber bipolar membrane electrodialysis device is sequentially provided with an anode electrolysis chamber, a dilute acid isolation chamber, an acid chamber, a center isolation chamber, a base chamber, a dilute base isolation chamber, and a cathode electrolysis chamber, the anode electrolysis chamber and the dilute acid isolation chamber are separated by a cation exchange membrane, the cathode electrolysis chamber and the dilute base isolation chamber are separated by an anion exchange membrane, the dilute acid isolation chamber and the acid chamber and the dilute base isolation chamber and the base chamber are separated by bipolar membranes, the acid chamber and the center isolation chamber are separated by an anion exchange membrane, and the base chamber and the center isolation chamber are separated by a cation exchange membrane; The concentrated water is delivered to the center isolation chamber, under the action of direct current electric field, Na + into the alkali chamber and OH - combined to generate NaOH, and the carboxylate ions ionized from the concentrated water into the acid chamber and H + combined to generate organic acid, and the dilute organic acid in the dilute acid isolation chamber is used as the circulating liquid of the acid chamber, and the dilute NaOH solution in the dilute alkali isolation chamber is used as the circulating liquid of the alkali chamber.

2. The treatment method of the glutaraldehyde condensation spent caustic solution according to claim 1, characterized by, The acid used in the acidification treatment is pentanoic acid; in the acidification treatment, the pH value of the pentanal condensation waste lye is adjusted to 0-6, and the temperature is 25-60°C.

3. The treatment method of the glutaraldehyde condensation spent caustic solution according to claim 1, characterized by, The layering is performed by centrifugation at a speed of 500-3000 rpm for 1-10 min; the obtained organic phase is used as a byproduct, or the obtained organic phase is transported to a rectifying tower for separation to obtain organic acid which is recycled for acidification treatment.

4. The treatment method of the glutaraldehyde condensation spent caustic solution according to claim 3, characterized by, The rectifying tower has 30-60 plates, the feed plate is 16-26, the reflux ratio is 1.9-2.9, the tower pressure is 5-50 kPa, the top temperature is 40-60°C, and the bottom temperature is 120-130°C.

5. The treatment method of the glutaraldehyde condensation spent caustic solution according to claim 1, characterized by, The distilled water obtained by concentrating the water phase is recycled for preparing the lye used in the pentanal condensation process.

6. The treatment method of the glutaraldehyde condensation spent caustic solution according to claim 1, characterized by, The concentration of sodium carboxylate in the concentrated water is 2-3 mol / L.

7. A system for treating a pentanal condensation spent caustic solution, comprising: It comprises: an acidification device for acidifying the pentanal condensation waste lye; a separation device in communication with the acidification device to separate the acidified pentanal condensation waste lye by layering to obtain organic phase and water phase; a concentration device in communication with the separation device to concentrate the water phase to obtain concentrated water; A five-chamber bipolar membrane electrodialysis device is in communication with the concentration device, and the five-chamber bipolar membrane electrodialysis device is sequentially provided with an anode electrolysis chamber, a dilute acid isolation chamber, an acid chamber, a center isolation chamber, a base chamber, a dilute base isolation chamber, and a cathode electrolysis chamber. The anode electrolysis chamber and the dilute acid isolation chamber are separated by a cation exchange membrane, the cathode electrolysis chamber and the dilute base isolation chamber are separated by an anion exchange membrane, the dilute acid isolation chamber and the acid chamber are separated by a bipolar membrane, the dilute base isolation chamber and the base chamber are separated by a bipolar membrane, the acid chamber and the center isolation chamber are separated by an anion exchange membrane, and the base chamber and the center isolation chamber are separated by a cation exchange membrane. The concentrated water is transported to the center isolation chamber, under the action of a direct current electric field, Na + into the base chamber and OH - combined to generate NaOH, and carboxylate ions ionized from the concentrated water enter the acid chamber and H + combined to generate an organic acid. Dilute organic acid in the dilute acid isolation chamber is used as the circulating liquid of the acid chamber, and dilute NaOH solution in the dilute base isolation chamber is used as the circulating liquid of the base chamber.

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