A clean and efficient electrochemical flow reactor device and method for vat dyes

Abstract

The application provides a clean and efficient electrochemical flow reaction device for vat dyes, which comprises a cathode electrolysis module, an anode electrolysis module and an ion exchange film, the cathode electrolysis module and the anode electrolysis module are arranged on the two sides of the ion exchange film, the outer sides of the cathode electrolysis module and the anode electrolysis module are provided with shell plates, the cathode electrolysis module comprises a cathode functional plate and a cathode plate, the anode electrolysis module comprises an anode functional plate and an anode plate, two pipes for liquid inlet and liquid outlet are arranged on the cathode functional plate and the anode functional plate respectively, the two sides of the ion exchange film are provided with films, the inner sides of the shell plates are provided with insulating plates, and the inner sides of the insulating plates are provided with backing plates. The device has the advantages of simple structure, convenient disassembly, assembly and modification, low cost, easy availability of the materials of the functional plate modules, selection of appropriate functional plates, ingenious design of electrodes, expansion of the electrode plate area, expansion of the electrode area, sufficient contact with the electrolyte, and great improvement of the electrolysis efficiency of the system.

Description

Technical Field

[0001] This invention relates to the field of dye reduction technology, and in particular to a clean and efficient electrochemical flow reaction apparatus and method for reducing dyes. Background Technology

[0002] Vat dyes are insoluble in water and require a strong alkaline reducing solution to dissolve into leuco sodium salts before they can adhere to the fibers. After oxidation, they revert to an insoluble dye lake that is fixed onto the fibers, generally exhibiting high wash and lightfastness. The commonly used reducing agent is sodium dithionite (commonly known as hydrosulfite). Hydrosulfite is chemically very reactive and can produce a strong reducing effect even at low temperatures under alkaline conditions. However, hydrosulfite is non-renewable, and its byproducts contain various sulfides, causing environmental pollution.

[0003] Electrochemical technology, as an emerging reduction method, is increasingly prominent due to its advantages in green and environmental protection. Electrochemical reduction technology uses electrical energy instead of oxidants and reductants to carry out redox reactions, avoiding the use of chemical reagents, reducing production costs, and decreasing wastewater discharge, thus aligning with the national green development concept.

[0004] Many methods for indirect electrochemical reduction of dyes have been disclosed in existing Chinese patents, but there are currently no methods for direct electrochemical reduction in China. This is because the commonly used electrolysis devices, such as single-cell, H-type, and plate-and-frame electrolysis cells, all have some problems: (1) The contact area between the electrode plates and the dye is limited. Since the dye is reduced by directly gaining electrons on the electrode, the limited area of ​​the electrode plates in the existing single-cell and H-type electrolysis cells cannot meet the technical requirements; (2) Electrochemical reactions are heterogeneous reactions that take place on the electrode surface. In the existing plate-and-frame electrolysis cells, only the electrolyte flowing through the surface in the cathode chamber can react, resulting in long reaction time and low reaction efficiency; (3) The electrode spacing in the existing plate-and-frame electrolysis cells is relatively large. Although there is a lot of electrolyte in the cathode and anode chambers, the amount of electrolyte reacting is negligible. Moreover, in industrial production, it is necessary to carry out the process at a high current density. The large electrode spacing will significantly increase the energy consumption and increase the production cost.

[0005] Therefore, it is necessary to design a clean and efficient electrochemical flow reaction device for vat dyes to overcome the above problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a clean and efficient electrochemical flow reaction apparatus and method for vat dyes.

[0007] This invention is implemented as follows:

[0008] This invention provides a clean and efficient electrochemical flow reaction device for vat dyes, comprising a cathode electrolysis module, an anodic electrolysis module, and an ion exchange membrane. The cathode electrolysis module and the anodic electrolysis module are respectively disposed on both sides of the ion exchange membrane. Both the cathode electrolysis module and the anodic electrolysis module are provided with outer shell plates. The cathode electrolysis module includes a cathode functional plate and a cathode plate, and the anodic electrolysis module includes an anode functional plate and an anode plate. Both the cathode functional plate and the anode functional plate are provided with two pipes for liquid inlet and liquid outlet, respectively. Thin films are provided on both sides of the ion exchange membrane, and an insulating plate is provided on the inner side of the outer shell plate. A pad is provided on the inner side of the insulating plate.

[0009] This device allows for the design of cathode and anode functional plates of appropriate shapes and sizes based on specific dye reactions, while also determining the functional models and dimensions of the anode, cathode, and ion exchange membrane. The cathode and anode functional plates are equipped with channels for electrolyte flow, ensuring a small pressure difference between the inside and outside of the membrane, facilitating control of the electrolyte flow rate. The small spacing between the electrodes also contributes to high electrode efficiency.

[0010] Furthermore, grooves are formed in the middle of the cathode functional plate, anode functional plate, thin film and insulating pad, and the grooves are stacked and combined to form the cathode chamber and anode chamber.

[0011] Depending on the specific reaction conditions, the cathode chamber can be filled with porous glassy carbon (RVC) to form a three-dimensional electrode system, further increasing the contact area between the dye and the electrode.

[0012] Furthermore, the outer cover plate, insulating plate, pad plate, cathode plate, cathode functional plate, plastic film, ion exchange membrane, anode functional plate, and anode plate are all provided with corresponding connection holes, and are connected to the connection holes with bolts after being stacked.

[0013] Furthermore, the cathode functional plate and the anode functional plate are polyetheretherketone (PEEK) plates, polyethylene plates, or polypropylene plates.

[0014] Furthermore, the cathode plate is made of one of the following materials: graphite, glassy carbon, platinum, titanium, nickel, ruthenium, and iridium.

[0015] Furthermore, the anode plate contains one of graphite, platinum, nickel, ruthenium, iridium, and titanium.

[0016] The present invention also provides an electrochemical flow reaction method for vat dyes, comprising the following steps:

[0017] An electrolyte is prepared, comprising a cathode solution and an anolyte, wherein the cathode solution is composed of a vat dye and an alkaline solution, and the anolyte is an alkaline solution;

[0018] The electrolyte is fed into the clean and efficient electrochemical flow reaction device for vat dyes described above, and reacts directly with the electrodes to perform direct electrochemical reduction of vat dyes. The temperature is controlled at 40-60℃, the feed flow rate is 0.1-0.3mL / s, and electrolysis is performed at 11-15V for 6-7 hours.

[0019] Specifically, the vat dye is one of indigo, vat yellow G, and vat maroon 2R.

[0020] The present invention has the following beneficial effects:

[0021] 1. The structure is simple, easy to disassemble, assemble, and modify, and the cost is low. The materials for each functional board module are readily available.

[0022] 2. By selecting appropriate functional plates and cleverly designing electrodes to expand the plate area, the electrode area can be increased, allowing for full contact with the electrolyte and significantly improving the system's electrolysis efficiency.

[0023] 3. Based on the characteristics of the dye being electrolyzed, the shape, size, and opening dimensions of the functional plate can be appropriately designed to control the amount of dye solution used in a single electrolysis. The electrodes can also be optimized, and a three-dimensional electrode system can be used to increase the dye electrolysis efficiency.

[0024] 4. Compared with existing technologies, the wastewater from electrolytic reduction produces no heavy metals or sulfur compounds, greatly reducing the cost of wastewater treatment.

[0025] 5. The capacity of the cathode and anode chambers can be expanded or reduced as needed. The device adopts a circulating feed system, which can control the feed flow rate and concentration, greatly increasing the electrolysis efficiency of the system. Furthermore, the electrolyzed vat dye can be reused.

[0026] 6. This device can also be used to scale up the reaction and apply it to production by simply stacking functional boards or connecting multiple flow devices in parallel. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the composition of the reaction apparatus provided in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the structure of the cathode functional plate / anode functional plate provided in an embodiment of the present invention;

[0030] Figure 3 A flow chart of the reduction reaction process provided in an embodiment of the present invention;

[0031] Figure 4 This is a graph showing the current variation when indigo is applied in Embodiment 1 of the present invention;

[0032] Figure 5 This is a graph showing the current change when the reduced yellow G is applied in Embodiment 2 of the present invention;

[0033] Figure 6 This is a current change diagram when the reduced red 2R is applied in Embodiment 3 of the present invention.

[0034] In the diagram: 1-Outer shell plate; 2-Cathode functional plate; 3-Cathode plate; 4-Anode functional plate; 5-Anode plate; 6-Ion exchange membrane; 7-Thin film; 8-Insulating plate; 9-Plate; 10-Pipe; 11-Groove; 12-Connecting hole; 13-Storage tank; 14-Peristaltic pump. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] See Figure 1 This invention provides a clean and efficient electrochemical flow reaction device for reducing dyes, comprising a cathode electrolysis module, an anode electrolysis module, and an ion exchange membrane 6. The cathode electrolysis module and the anode electrolysis module are respectively disposed on both sides of the ion exchange membrane 6. Both the cathode electrolysis module and the anode electrolysis module are provided with an outer shell plate 1. The cathode electrolysis module includes a cathode functional plate 2 and a cathode plate 3, and the anode electrolysis module includes an anode functional plate 4 and an anode plate 5. Both the cathode functional plate 2 and the anode functional plate 4 are provided with two pipes 10 for liquid inlet and liquid outlet, respectively. Thin films 7 are provided on both sides of the ion exchange membrane 6, and an insulating plate 8 is provided on the inner side of the outer shell plate 1. A pad 9 is provided on the inner side of the insulating plate 8.

[0037] The insulating plate 8 is made of rigid insulating plastic, including nylon, epoxy resin, phenolic resin, polyetheretherketone, polyethylene, and polypropylene. Its main function is to ensure insulation and it also serves as a carrier for the liquid flow channel. The pad 9 is made of softer insulating plastic, including rubber, polyethylene, and polypropylene, primarily to prevent deformation of the metal electrode plates during extrusion. The film 7 is a plastic film with good adhesion, mainly used to fix the ion exchange membrane 6 and prevent membrane displacement due to the voltage difference between the cathode and anode during electrolysis. The cathode functional plate 2 and the anode functional plate 4 are polyetheretherketone, polyethylene, or polypropylene plates. The cathode plate 3 is made of one of the following materials: graphite, glassy carbon, platinum, titanium, nickel, ruthenium, or iridium. The anode plate 5 is made of one of the following materials: graphite, platinum, nickel, ruthenium, iridium, or titanium.

[0038] like Figure 1 , Figure 2 As shown, grooves 11 are formed in the middle of the cathode functional plate 2, the anode functional plate 4, the thin film 7, and the pad 9. The grooves 11 are stacked and combined to form the cathode chamber and the anode chamber. Depending on the specific reaction conditions, the cathode chamber can be filled with RVC porous glassy carbon or the like to form a three-dimensional electrode system, further increasing the contact area between the dye and the electrode.

[0039] Each component has a corresponding connection hole 12, and the components are stacked and fixed together with bolts at the connection holes 12. After assembly, the reaction device occupies little space, and the stacked design facilitates disassembly and replacement when internal parts are damaged.

[0040] In existing technologies, the electrode spacing is relatively large. Although a large amount of electrolyte passes through the electrolysis chamber, very little electrolyte is used for the reaction. In industrial production, it is necessary to significantly improve the electrolysis efficiency of the system. However, the electrode spacing of this reaction device is small, the contact area between the electrolyte and the electrode is large, and the electrolysis efficiency is high.

[0041] like Figure 3 As shown, the cathode functional plate 2 and anode functional plate 4 of the reaction device are respectively connected to the storage tank 13 (only one is shown in the figure). The peristaltic pump 14 drives the flow of cathode liquid or anolyte (electrolyte). The reaction device provides channels for the flow of electrolyte within the cathode functional plate 2 and anode functional plate 4. The cathode liquid enters from the cathode inlet, enters the cathode chamber and contacts the electrode for electrolysis, and then exits from the cathode outlet. The anolyte enters from the anode inlet, enters the anode chamber for electrolysis, and then exits from the anode outlet. The cycle continues until the reducing dye is completely electrolyzed and reduced, reaching the electrolysis endpoint.

[0042] Example 1

[0043] This device is used to reduce indigo dye. The electrolyte enters the cathode functional plate 2 and the anode functional plate 4. The cathode solution is prepared by dissolving 80 g / L of the vat dye in a 1M sodium hydroxide solution, and the anode solution is also a 1M sodium hydroxide solution. The temperature is controlled at 40-60℃, the feed flow rate is 0.1-0.3 mL / s, and electrolysis is performed at 11-15V for 6-7 hours. Current changes are recorded. Figure 4 As shown, when the current is approximately 0A, the electrolysis endpoint is reached, the electrolysis is completed, and its reduction potential is measured.

[0044] Example 2

[0045] Taking the reduction of Yellow G dye using this device as an example, the electrolyte enters the cathode functional plate 2 and the anode functional plate 4. The cathode solution is prepared by dissolving 80 g / L of the reduction dye in a 1M sodium hydroxide solution, and the anode solution is also a 1M sodium hydroxide solution. The temperature is controlled at 40-60℃, the feed flow rate is 0.1-0.3 mL / s, and electrolysis is performed at 11-15V for 6-7 hours. Current changes are recorded. Figure 5 As shown, when the current is approximately 0A, the electrolysis endpoint is reached, the electrolysis is completed, and its reduction potential is measured.

[0046] Example 3

[0047] This device was used to reduce maroon 2R dye. The electrolyte entered the cathode functional plate 2 and the anode functional plate 4. The cathode solution was prepared by dissolving 80 g / L of the vat dye in a 1M sodium hydroxide solution, and the anode solution was also a 1M sodium hydroxide solution. The temperature was controlled at 40-60℃, the feed flow rate at 0.1-0.3 mL / s, and electrolysis was performed at 11-15V for 6-7 hours. Current changes were recorded. Figure 6 As shown, when the current is approximately 0A, the electrolysis endpoint is reached, the electrolysis is completed, and its reduction potential is measured.

[0048] The reduction potentials measured in Examples 1-3 were around -760mV. Since the reduction potential of indigo is approximately -760mV, this indicates that the conditions for electrolytic reduction have been met, and the reactants and products meet the expected results.

[0049] In summary, the clean and efficient electrochemical flow reaction device for vat dyes of the present invention, equipped with suitable cathodic and anodic solutions, directly electrochemically reduces vat dyes by reacting with the electrodes, achieving a good reduction effect.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electrochemical flow reaction method for the reduction of a dye, characterized in that, It comprises the following steps: Preparation of electrolyte, the electrolyte includes catholyte and anolyte, the composition of catholyte is vat dye and alkaline solution, anolyte is alkaline solution; The vat dye is one of indigo, vat yellow G and vat bordeaux 2R; The electrolyte is sent into the clean and efficient electrochemical flow reaction device for vat dye to directly contact and react with the electrode to directly electrochemically reduce the vat dye, the temperature is controlled at 40-60 DEG C, the feed flow rate is 0.1-0.3 mL / s, the voltage is 11-15 V for electrolysis, and the power is on for 6-7 hours for electrolysis; The clean and efficient electrochemical flow reaction device for vat dye comprises a cathode electrolysis module, an anode electrolysis module and an ion exchange membrane, the cathode electrolysis module and the anode electrolysis module are arranged on the two sides of the ion exchange membrane, the outer sides of the cathode electrolysis module and the anode electrolysis module are provided with outer shell plates, the cathode electrolysis module comprises a cathode functional plate and a cathode plate, the anode electrolysis module comprises an anode functional plate and an anode plate, two pipes for feeding and discharging liquid are arranged on the cathode functional plate and the anode functional plate, thin films are arranged on the two sides of the ion exchange membrane, insulating plates are arranged on the inner sides of the outer shell plates, and backing plates are arranged on the inner sides of the insulating plates;Grooves are formed in the middle parts of the cathode functional plate, the anode functional plate, the thin films and the insulating backing plates, and the grooves are combined to form cathode chambers and anode chambers.

2. The electrochemical flow reaction method for vat dyes according to claim 1, characterized by: The outer cover plate, the insulating plate, the backing plate, the cathode plate, the cathode functional plate, the plastic film, the ion exchange membrane, the anode functional plate and the anode plate are provided with corresponding connecting hole positions, and are connected by bolts at the connecting hole positions after being stacked.

3. The electrochemical flow reaction method for the reduction of dyes according to claim 2, characterized in that: The cathode functional plate and the anode functional plate are polyether ether ketone plates or polyethylene plates or polypropylene plates.

4. The electrochemical flow reaction method for the reduction of dyes according to claim 2, characterized in that: The material of the cathode plate is one of graphite, glassy carbon, platinum, titanium, nickel, ruthenium and iridium.

5. The electrochemical flow reaction method for the reduction of dyes according to claim 2, characterized in that: The material of the anode plate is one of graphite, platinum, nickel, ruthenium, iridium and titanium.

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