Electrochemical method for recycling acetylsalicylic acid through deprotonation-protonation bidirectional control

Abstract

The invention discloses a deprotonation-protonation two-way control acetylsalicylic acid recovery electrochemical method, equipment adopted by the electrochemical method comprises a bipolar membrane electrodialysis device and a microfiltration membrane device, the bipolar membrane electrodialysis device comprises a membrane stack, the membrane stack is composed of at least one group of bipolar membrane electrodialysis units, and the microfiltration membrane device is connected with the bipolar membrane electrodialysis units. The group of bipolar membrane electrodialysis units consists of a crystallization chamber and a wastewater chamber which are formed by sequentially arranging bipolar membranes, anion exchange membranes and bipolar membranes at intervals; the electrochemical method specifically comprises the following steps: respectively introducing wastewater containing acetylsalicylic acid and sodium acetylsalicylate and deionized water into a wastewater chamber and a crystallization chamber, taking effluent of the crystallization chamber as inlet water of a micro-filtration membrane device, and taking effluent of the micro-filtration membrane device as inlet water of the crystallization chamber again; electrifying the equipment, and recovering acetylsalicylic acid crystals through a micro-filtration membrane. The method provided by the invention can effectively realize trapping and recovery of high-purity acetylsalicylic acid in wastewater, and has good environmental and economic benefits.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment, and in particular to an electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation. Background Art

[0002] Aspirin, as a widely used drug, is widely used in the medical field. Its chemical name is acetylsalicylic acid, which is famous for its anti-inflammatory, analgesic and antipyretic effects. About 35,000 tons of aspirin are produced worldwide each year. my country's aspirin consumption is about 4,000 tons per year, and its demand is still increasing year by year. In the production process of aspirin, a large amount of residual liquid containing acetylsalicylic acid or sodium acetylsalicylate is often produced. If it is not effectively treated, acetylsalicylic acid or sodium acetylsalicylate will enter the water environment and cause serious harm to aquatic organisms and ecosystems.

[0003] At present, the main treatment method for residual wastewater containing acetylsalicylic acid or sodium acetylsalicylate is to completely hydrolyze the acetylsalicylic acid residue into salicylic acid, then recover the salicylic acid by cooling and centrifugation, and the mother liquor is subjected to biochemical treatment in the sewage treatment plant. However, this treatment process consumes a large amount of liquid alkali and sulfuric acid, which does not meet the requirements of green and clean production in my country. At the same time, the hydrolysis of acetylsalicylic acid residues into salicylic acid indirectly leads to further loss of high value-added resources, which does not meet the goal of sustainable development. In addition, it has been reported that the electrochemical oxidation method was used to treat acetylsalicylic acid wastewater, and the removal rates of acetylsalicylic acid and COD were 96.88% and 67.85%, respectively. However, although the electrochemical oxidation method can effectively remove acetylsalicylic acid from the water body, it cannot realize its resource reuse. Therefore, if an effective method can be proposed to realize the resource regeneration of acetylsalicylic acid in acetylsalicylic acid wastewater, it can further promote the development of circular economy.

[0004] Membrane separation technology is a new separation technology in the 21st century. It mainly uses the selective separation of membranes to separate, purify and concentrate different components in the feed liquid. Bipolar membrane electrodialysis is an advanced electrochemical separation technology that is widely used in water treatment and resource recovery. However, acetylsalicylic acid usually exists in the form of molecules in wastewater, and its migration and enrichment cannot be achieved under the drive of an electric field. Therefore, how to design a bipolar membrane electrodialysis with a special configuration to achieve the directional migration and enrichment of acetylsalicylic acid under the drive of an electric field needs further exploration. In addition, when the concentrated acetylsalicylic acid crystals, it will inevitably contaminate the ion exchange membrane in the bipolar membrane electrodialysis system, seriously affecting the operational stability of the membrane system.

[0005] The present invention is devoted to exploring the use of electrochemical methods to control the protonation and deprotonation process of acetylsalicylic acid in pharmaceutical wastewater to achieve its resource recovery, and to develop a simple and efficient electrochemical method for deprotonation-protonation bidirectional control of acetylsalicylic acid recovery. Summary of the invention

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a simple and efficient method for resource recovery of high-purity acetylsalicylic acid from pharmaceutical wastewater.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] An electrochemical method for deprotonation-protonation bidirectional control of acetylsalicylic acid recovery, the electrochemical method adopts equipment including a bipolar membrane electrodialysis device and a microfiltration membrane device, the bipolar membrane electrodialysis device includes polar liquid chambers located on both sides and a membrane stack sandwiched between the polar liquid chambers on both sides, the membrane stack is composed of at least one group of bipolar membrane electrodialysis units, the group of bipolar membrane electrodialysis units is composed of a crystallization chamber and a wastewater chamber composed of a bipolar membrane, an anion exchange membrane and a bipolar membrane arranged in sequence; the electrochemical method specifically comprises: wastewater containing acetylsalicylic acid and sodium acetylsalicylate and deionized water are respectively introduced into the wastewater chamber and the crystallization chamber, and the effluent of the crystallization chamber is simultaneously introduced into the wastewater chamber and the crystallization chamber. The water outlet of the microfiltration membrane device is used as the inlet water of the crystallization chamber of the bipolar membrane electrodialysis device. The equipment is powered on. In the wastewater chamber, the hydroxyl ions generated by the water dissociation of the bipolar membrane are used to deprotonate the molecular acetylsalicylic acid to form acetylsalicylic acid ions. The acetylsalicylic acid ions formed by the original sodium acetylsalicylate in the wastewater are driven by the anion exchange membrane to enter the crystallization chamber for enrichment and concentration. The hydrogen ions generated by the water dissociation of the bipolar membrane on the other side of the crystallization chamber are used to protonate and crystallize the acetylsalicylic acid ions in the crystallization chamber to form crystals. The water outlet of the crystallization chamber enters the microfiltration membrane device, and the acetylsalicylic acid crystals are recovered through the microfiltration membrane.

[0009] The wastewater containing acetylsalicylic acid and sodium acetylsalicylate described in the present invention refers to the wastewater containing acetylsalicylic acid and sodium acetylsalicylate generated in the production process of aspirin. In a specific embodiment of the present invention, the wastewater containing acetylsalicylic acid and sodium acetylsalicylate contains 0.2-0.3 g / L acetylsalicylic acid and 0.3-0.4 g / L sodium acetylsalicylate.

[0010] Preferably, the anion exchange membrane is a homogeneous membrane.

[0011] Preferably, the bipolar membrane electrodialysis device is operated in a constant voltage mode with a voltage of 3-10V.

[0012] Preferably, the membrane stack is formed by n groups of bipolar membrane electrodialysis units connected in series, and the value of n is 1-10.

[0013] Preferably, the temperature of the feed solution in the polar liquid chamber, the crystallization chamber and the wastewater chamber is adjusted to 10-30°C.

[0014] Preferably, the volume ratio of the material to the liquid in the wastewater chamber and the crystallization chamber is 15:1-30:1.

[0015] Preferably, the flow rates of the feed liquid in the wastewater chamber and the crystallization chamber are 10-50 L / h respectively.

[0016] Preferably, the pore size of the microfiltration membrane is no greater than 1 μm.

[0017] Preferably, the microfiltration operating pressure is 0.01-0.1 MPa.

[0018] Preferably, the polar liquid in the polar liquid chamber is an aqueous solution of sodium sulfate.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention proposes an electrochemical method of bipolar membrane electrodialysis-microfiltration to effectively realize the efficient resource recovery of acetylsalicylic acid in pharmaceutical wastewater. The operation is simple and easy, which helps to reduce the consumption of liquid alkali and sulfuric acid in traditional methods. High-purity acetylsalicylic acid can be recovered without the addition of any chemical reagents, saving production costs, improving the economic benefits of the enterprise, and complying with the sustainable development concept of ecological protection.

[0021] (2) The design of the bipolar membrane electrodialysis-microfiltration system can effectively solve the surface contamination of the ion exchange membrane, improve the operational stability of the membrane system, and provide reference and technical support for new pharmaceutical, chemical, and pesticide companies that use membrane technology.

[0022] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a diagram of a bipolar membrane electrodialysis-microfiltration system of the present invention;

[0024] Figure 2 is a surface morphology image (SEM) of acetylsalicylic acid recovered in Example 1 of the present invention;

[0025] Figure 3 This is the X-ray diffraction pattern (XRD) of acetylsalicylic acid recovered in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0027] In the drawings, components with the same structure are indicated by the same numerical reference numerals, and components with similar structures or functions are indicated by similar numerical reference numerals. The size and thickness of each component shown in the drawings are arbitrarily shown, and the present invention does not limit the size and thickness of each component. In order to make the illustration clearer, the thickness of the components is appropriately exaggerated in some places in the drawings.

[0028] The following describes several preferred embodiments of the present invention with reference to the drawings in the specification, so that the technical content is clearer and easier to understand. The present invention can be embodied in many different forms of embodiments, and the protection scope of the present invention is not limited to the embodiments mentioned in the text.

[0029] Example 1

[0030] (1) Figure 1 Constructing a bipolar membrane electrodialysis-microfiltration electrochemical system: from left to right, the bipolar membrane, anion exchange membrane, and bipolar membrane are divided into a polar chamber, a crystallization chamber, a wastewater chamber, and a polar chamber; the effluent of the crystallization chamber is used as the influent of the microfiltration membrane device, and the effluent of the microfiltration membrane device is used as the influent of the bipolar membrane electrodialysis crystallization chamber again; the bipolar membrane electrodialysis system is externally connected to a DC power supply;

[0031] (2) 500 mL of 3 wt% sodium sulfate solution was added to each of the two polar chambers, 1500 mL of wastewater containing acetylsalicylic acid and sodium acetylsalicylate (acetylsalicylic acid concentration 0.2 g / L, sodium acetylsalicylate concentration 0.37 g / L) was added to the wastewater chamber, and 100 mL of deionized water was added to the crystallization chamber (wastewater chamber: crystallization chamber solution volume ratio 15:1). The ion exchange membranes used were FBM / AHA / FBM, FBM was an FBM type bipolar membrane (Fuma-Tech Co, Germany), AHA was an AHA type anion exchange membrane (ASTOM Co, Japan), and the effective area of ​​each membrane was 189 cm 2 The circulation pump was turned on, and the feed rate of each compartment was 10L / h. The bipolar membrane electrodialysis device was powered on to treat at a constant voltage of 3V. The experiment was stopped when the alkali concentration in the wastewater chamber no longer increased. At the same time, the pressure of the microfiltration membrane device was adjusted to 0.01MPa, and the pore size of the microfiltration membrane was 0.22μm. The experiment took 180 minutes, and the microfiltration membrane recovered 0.32g of long crystals (such as Figure 2 ), XRD analysis showed that the crystals were acetylsalicylic acid (such as Figure 3 ), the yield is 40.25%, the purity is 99.3%. The current efficiency of bipolar membrane electrodialysis is 41.25%, and the energy consumption is 5.17 kWh / kg.

[0032] Example 2

[0033] Referring to Example 1, step 2) 1500mL of acetylsalicylic acid wastewater (wherein the concentration of acetylsalicylic acid is 0.21g / L, the concentration of sodium acetylsalicylate is 0.37g / L) is added to the wastewater chamber, and 100mL of deionized water (wastewater chamber: crystallization chamber solution volume ratio is 15:1) is added to the crystallization chamber. The operating voltage is 6V, and the microfiltration membrane device pressure is 0.05MPa for treatment. The experiment took 120 minutes, and the microfiltration membrane recovered 0.55g of acetylsalicylic acid crystals, with a yield of 69.18% and a purity of 99.2%. The current efficiency of bipolar membrane electrodialysis is 55.34%, and the energy consumption is 5.78kWh / kg.

[0034] Example 3

[0035] Referring to Example 1, step 2) 1500mL of acetylsalicylic acid wastewater (wherein the concentration of acetylsalicylic acid is 0.21g / L, the concentration of sodium acetylsalicylate is 0.37g / L) is added to the wastewater chamber, and 100mL of deionized water is added to the crystallization chamber (wastewater chamber: crystallization chamber solution volume ratio is 15:1), and the feed rate of each compartment is 30L / h. The operating voltage is 10V, and the microfiltration membrane device pressure is 0.1MPa for treatment. The experiment took 90 minutes, and the microfiltration membrane recovered 0.65g of acetylsalicylic acid crystals, with a yield of 81.76% and a purity of 99.3%. The current efficiency of bipolar membrane electrodialysis is 59.33%, and the energy consumption is 6.24kWh / kg.

[0036] Example 4

[0037] Referring to Example 1, step 2) 3000mL of acetylsalicylic acid wastewater (wherein the concentration of acetylsalicylic acid is 0.2g / L, the concentration of sodium acetylsalicylate is 0.35g / L) is added to the wastewater chamber, and 100mL of deionized water (wastewater chamber: crystallization chamber solution volume ratio is 30:1) is added to the crystallization chamber. The operating voltage is 10V, and the microfiltration membrane device pressure is 0.1MPa for treatment. The experiment took 170 minutes, and the microfiltration membrane recovered 1.28g of acetylsalicylic acid crystals, with a yield of 80.50% and a purity of 99.4%. The current efficiency of bipolar membrane electrodialysis is 56.41%, and the energy consumption is 6.62kWh / kg.

[0038] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. An electrochemical method for bidirectionally controlling the recovery of acetylsalicylic acid by deprotonation-protonation, characterized in that: The equipment used in the electrochemical method includes a bipolar membrane electrodialysis device and a microfiltration membrane device, wherein the bipolar membrane electrodialysis device includes polar liquid chambers located on both sides and a membrane stack sandwiched between the polar liquid chambers on both sides, wherein the membrane stack is composed of at least one group of bipolar membrane electrodialysis units, wherein the group of bipolar membrane electrodialysis units is composed of a crystallization chamber and a wastewater chamber composed of a bipolar membrane, an anion exchange membrane and a bipolar membrane arranged in sequence; the electrochemical method is specifically as follows: wastewater containing acetylsalicylic acid and sodium acetylsalicylate and deionized water are respectively introduced into the wastewater chamber and the crystallization chamber, and the effluent of the crystallization chamber is used as the inlet of the microfiltration membrane device, and the microfiltration membrane The effluent of the device is used as the inlet water of the crystallization chamber of the bipolar membrane electrodialysis device again; the device is powered on, and in the wastewater chamber, the hydroxyl ions generated by the bipolar membrane water dissociation are used to realize the deprotonation of molecular acetylsalicylic acid to form acetylsalicylic acid root ions, and together with the acetylsalicylic acid root formed by the original sodium acetylsalicylate in the wastewater, they enter the crystallization chamber through the anion exchange membrane under the driving of the electric field for enrichment and concentration, and the hydrogen ions generated by the bipolar membrane water dissociation on the other side of the crystallization chamber are used to realize the protonation and crystallization of the acetylsalicylic acid root ions in the crystallization chamber to generate crystals, and the effluent of the crystallization chamber enters the microfiltration membrane device, and the acetylsalicylic acid crystals are recovered through the microfiltration membrane.

2. The electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation as claimed in claim 1, characterized in that: The wastewater containing acetylsalicylic acid and sodium acetylsalicylate refers to the wastewater containing acetylsalicylic acid and sodium acetylsalicylate generated in the production process of aspirin.

3. The electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation as claimed in claim 1, characterized in that: The wastewater containing acetylsalicylic acid and sodium acetylsalicylate contains 0.2-0.3 g / L acetylsalicylic acid and 0.3-0.4 g / L sodium acetylsalicylate.

4. The electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation as claimed in any one of claims 1 to 3, characterized in that: The bipolar membrane electrodialysis device adopts a constant voltage operation mode during operation, with a voltage of 3-10V.

5. The electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation as claimed in any one of claims 1 to 3, characterized in that: The membrane stack is formed by connecting n groups of bipolar membrane electrodialysis units in series, and the value of n is 1-10.

6. The electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation as claimed in any one of claims 1 to 3, characterized in that: The temperatures of the feed solutions in the polar liquid chamber, the crystallization chamber and the wastewater chamber are all adjusted to 10-30°C.

7. The electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation as claimed in any one of claims 1 to 3, characterized in that: The volume ratio of the material to the liquid in the wastewater chamber and the crystallization chamber is 15:1-30:

1.

8. The electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation as claimed in any one of claims 1 to 3, characterized in that: The flow rates of the feed liquid in the wastewater chamber and the crystallization chamber are 10-50 L / h respectively.

9. The electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation as claimed in any one of claims 1 to 3, characterized in that: The pore size of the microfiltration membrane is no more than 1 μm, and the microfiltration operating pressure is 0.01-0.1 MPa.

10. The electrochemical method for recovering acetylsalicylic acid by bidirectionally controlling deprotonation and protonation as claimed in any one of claims 1 to 3, characterized in that: The anion exchange membrane is a homogeneous membrane.

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