Regeneration and reuse treatment device and method for chromium-containing sulfuric acid waste liquid

Abstract

The invention discloses a chromium-containing sulfuric acid waste liquid regeneration and reuse treatment device which is characterized in that trivalent chromium in an anode region is oxidized into hexavalent chromium and hexavalent chromium in a cathode region is reduced into trivalent chromium in the process that chromium-containing sulfuric acid waste liquid enters a reactor for reaction through a graded membrane structure in a graded membrane electrochemical reactor; and the diaphragm prevents diffusion of hexavalent chromium in an anode region, so that valence state aggregation and concentration of trivalent chromium and hexavalent chromium are realized, and the resource utilization efficiency is greatly improved. Meanwhile, outlet water obtained after reaction of the graded membrane electrochemical reactor flows back to the sample barrel and the reference barrel and is input into the graded membrane electrochemical reactor again through the refrigerator to react again, and circulation in the anode chamber and circulation in the cathode chamber are formed; the service life of the electrode is effectively prolonged; and the reduction of electrochemical reaction efficiency caused by over-high temperature is prevented. In the process, the reaction can be easily cooled through a refrigerator, the situation that the electrolytic reaction efficiency is reduced due to the fact that the temperature is too high is avoided, and the regeneration and reuse effect of chromium is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a device and method for regenerating and reusing chromium-containing sulfuric acid waste liquid. Background Art

[0002] Chromium has high hardness, gloss and corrosion resistance. Due to its good elasticity and adaptability, wide temperature resistance range and stable chemical properties, it is widely used in the chemical industry, biological field and environmental protection field. However, in the preparation of materials containing chromium, a large amount of chromium-containing waste acid is often produced, which will cause serious environmental pollution problems. Therefore, it is necessary to regenerate and reuse the chromium-containing sulfuric acid waste liquid to prevent pollution to the environment. At the same time, it can also save costs by recycling materials such as sulfuric acid and chromium, and realize the recycling of resources.

[0003] At present, electrochemical methods are usually used to treat high-concentration chromium-containing waste acid generated in industrial processes. Among them, the diaphragm electro-oxidation method has good separation effect, no need for external agents, and high conversion efficiency. It is often used for material separation and wastewater regeneration, and is suitable for treating high-concentration chromium-containing waste acid. When using the diaphragm electro-oxidation method to treat chromium-containing waste acid, the trivalent chromium in the waste acid can be oxidized to hexavalent chromium in the anode chamber and reused in the production process, avoiding the discharge of a large amount of chromium-containing waste acid, while also reducing the addition of chromium raw materials, and realizing the resource regeneration of chromium-containing waste acid.

[0004] However, the applicant has found that when the diaphragm electro-oxidation method is used to treat chromium-containing waste acid, an ion membrane is often used as a diaphragm, which has the problems of high cost and short life. On the other hand, in terms of electrode materials, there is a phenomenon of catalyst corrosion and dissolution, which leads to impurities in the regenerated sulfuric acid, affecting its recycling performance. In addition, when the diaphragm electro-oxidation method is used to treat chromium-containing waste acid, the electrode reaction generates heat, resulting in an increase in the system temperature, which easily leads to a decrease in the efficiency of the electrochemical reaction or a shortened electrode life. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problems in the above-mentioned prior art that the electrode life is shortened, the system regeneration and reuse performance is poor, and the system temperature is easily increased due to the heat generated by the reaction, which ultimately leads to a decrease in the electrochemical reaction efficiency. A regeneration and reuse treatment device for chromium-containing sulfuric acid waste liquid is provided, which can extend the electrode life while effectively avoiding the problem of reduced electrochemical reaction efficiency caused by excessively high temperature, thereby improving the regeneration and reuse rate of chromium.

[0006] In order to solve the above problems, the present invention is implemented according to the following technical solutions:

[0007] The present invention provides a regeneration and reuse treatment device for chromium-containing sulfuric acid waste liquid, comprising:

[0008] Multi-stage diaphragm electrochemical reactor;

[0009] Filters;

[0010] A sample barrel, the sample barrel is connected to the filter, and the sample barrel is used to store the chromium-containing sulfuric acid waste liquid filtered by the filter and the effluent of the anode area after the reaction of the multi-stage diaphragm electrochemical reactor;

[0011] A reference barrel, the reference barrel is connected to the filter, and the reference barrel is used to store the chromium-containing sulfuric acid waste liquid filtered by the filter and the effluent of the cathode area after the reaction of the multi-stage diaphragm electrochemical reactor;

[0012] A water pump, the water pump comprising a first water pump and a second water pump, the first water pump being connected to the sample barrel, and the second water pump being connected to the reference barrel;

[0013] A refrigerator, the refrigerator comprising a first refrigerator and a second refrigerator, the first refrigerator is connected to the first water pump, and the second refrigerator is connected to the second water pump;

[0014] A flow meter, the flow meter comprising a first flow meter and a second flow meter, the first flow meter is connected to a first refrigerator, the second flow meter is connected to a second refrigerator, and the first flow meter and the second flow meter are both connected to the multi-stage membrane electrochemical reactor;

[0015] A power source connected to the multi-stage diaphragm electrochemical reactor;

[0016] The multi-stage membrane electrochemical reactor has an anode chamber and a cathode chamber separated by a membrane, a rubber pad and a partition to prevent heat accumulation during the reaction process.

[0017] As a preferred implementation, the diaphragm is a special diaphragm.

[0018] As a preferred embodiment, the refrigerator is a low-temperature constant bath device, and the refrigerator is used to exchange heat with the outlet water after the reaction in the multi-stage diaphragm electrochemical reactor.

[0019] As a preferred embodiment, the inter-electrode distances between the electrode assemblies in the multi-stage diaphragm electrochemical reactor are equal.

[0020] As a preferred implementation, the inter-electrode distance ranges from 5 to 30 mm.

[0021] As a preferred embodiment, the anode plate of the multi-stage diaphragm electrochemical reactor is a titanium-based lead dioxide anode plate, and the cathode plate of the multi-stage diaphragm electrochemical reactor is a lead cathode plate.

[0022] As a preferred embodiment, the graded membrane electrochemical reactor has fixing nuts for fixing the anode plate, cathode plate, diaphragm and separator.

[0023] As a preferred implementation, the fixing nut is made of PP or UPVC.

[0024] As a preferred implementation, the water pump is a centrifugal magnetic pump.

[0025] The present invention also provides a method for regenerating and reusing chromium-containing sulfuric acid waste liquid, which is implemented based on the regenerating and reusing treatment device for chromium-containing sulfuric acid waste liquid described in any one of the above, and the method comprises the following steps:

[0026] (1) transporting the chromium-containing sulfuric acid waste liquid to a filter for filtering;

[0027] (2) transferring the chromium-containing sulfuric acid waste liquid filtered by the filter in step (1) to a sample barrel and a reference barrel until the water levels in the sample barrel and the reference barrel are consistent;

[0028] (3) transporting the chromium-containing sulfuric acid waste liquid in the sample barrel and the reference barrel to a graded membrane electrochemical reactor for reaction;

[0029] (4) Under the action of the electric field, a large number of free radicals and ions are generated on the surface of the anode plate, so that the trivalent chromium in the anode chamber is oxidized to hexavalent chromium by the free radicals and ions; the hexavalent chromium in the cathode chamber is reduced to trivalent chromium;

[0030] (5) transporting the effluent in the anode chamber after the reaction in step (4) to a sample bucket; transporting the effluent in the cathode chamber after the reaction in step (4) to a reference bucket;

[0031] (6) The water outlet from the sample barrel in step (5) is transported to a refrigerator through a water pump for heat exchange, and the water outlet after heat exchange is transported to the graded membrane electrochemical reactor again for reaction to form a circulation in the anode chamber; the water outlet from the reference barrel in step (5) is transported to a refrigerator through a water pump for heat exchange, and the water outlet after heat exchange is transported to the graded membrane electrochemical reactor again for reaction to form a circulation in the cathode chamber.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention provides a regeneration and reuse treatment device and method for chromium-containing sulfuric acid waste liquid. The chromium-containing sulfuric acid waste liquid enters the reactor reaction process through the graded membrane structure in the graded membrane electrochemical reactor. The trivalent chromium in the anode area is oxidized to hexavalent chromium, and the hexavalent chromium in the cathode area is reduced to trivalent chromium. The diaphragm prevents the diffusion of the hexavalent chromium in the anode area, and the trivalent chromium and hexavalent chromium are concentrated in the valence state, which greatly improves the resource utilization efficiency. At the same time, the effluent of the graded membrane electrochemical reactor after the reaction flows back to the sample barrel and the reference barrel, and is re-input into the graded membrane electrochemical reactor through the refrigerator to react again, forming a circulation in the anode chamber and a circulation in the cathode chamber, effectively extending the service life of the electrode and preventing the electrochemical reaction efficiency from being reduced due to excessive temperature. In this process, the reaction can be cooled by the refrigerator to avoid the reduction of the electrolytic reaction efficiency due to excessive temperature, and the regeneration and reuse effect of chromium is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings, wherein:

[0035] Figure 1 It is a structural principle diagram of a regeneration and reuse treatment device for chromium-containing sulfuric acid waste liquid of the present invention;

[0036] Figure 2 It is a diagram of the internal hierarchical membrane structure of the hierarchical membrane electrochemical reactor of the present invention;

[0037] In the figure:

[0038] 11-filter barrel, 12-filter;

[0039] 21 - sample barrel, 22 - first water pump, 23 - first refrigerator, 24 - first flow meter;

[0040] 31 - reference barrel, 32 - second water pump, 33 - second refrigerator, 34 - second flow meter;

[0041] 40 - multi-stage membrane electrochemical reactor, 41 - bottom plate, 421 - first separator, 422 - second separator, 423 - third separator, 424 - fourth separator, 43 anode plate, 44 - diaphragm, 45 - cathode plate;

[0042] 50- Power supply. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0044] The terms used in this application are only for the purpose of describing specific embodiments and are not intended to limit this application. Unless otherwise defined, the technical terms or scientific terms used in this specification should be understood by people with ordinary skills in the field to which this application belongs. The words "first", "second" and similar words used in this specification and claims do not indicate any order, quantity or importance, but are only used to distinguish different technical features.

[0045] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0046] Chromium is widely used in many fields due to its good elasticity and adaptability, wide temperature resistance and stable chemical properties. However, in the preparation of materials containing chromium, a large amount of chromium-containing waste acid is often produced, which will cause serious environmental pollution problems. Therefore, it is necessary to regenerate and reuse the chromium-containing sulfuric acid waste liquid to prevent pollution to the environment and realize the recycling of resources.

[0047] At present, diaphragm electro-oxidation is usually used for high-concentration chromium-containing waste acid generated in industrial processes. However, in the actual diaphragm electro-oxidation method for treating chromium-containing waste acid, an ion membrane is often used as a diaphragm, which has problems such as high cost of use and short life. On the other hand, in terms of electrode materials, there is a phenomenon of catalyst corrosion and dissolution, which leads to impurities in the regenerated sulfuric acid, affecting its recycling performance. In addition, when using the diaphragm electro-oxidation method to treat chromium-containing waste acid, the electrode reaction will generate heat, causing the system temperature to rise, which can easily lead to a decrease in the efficiency of the electrochemical reaction or a shortened electrode life.

[0048] In order to solve the technical problems in the above-mentioned prior art that the electrode life is shortened and the system regeneration and reuse performance is poor when regenerating and reusing chromium-containing waste sulfuric acid, and the system temperature is easily increased due to the heat generated by the reaction, which ultimately leads to a decrease in the electrochemical reaction efficiency, a regeneration and reuse treatment device for chromium-containing sulfuric acid waste liquid is provided. The device can extend the electrode life while effectively avoiding the problem of reduced electrochemical reaction efficiency caused by excessively high temperature, thereby improving the regeneration and reuse rate of chromium.

[0049] The invention discloses a regeneration and reuse treatment device for chromium-containing sulfuric acid waste liquid, comprising: a multi-stage diaphragm electrochemical reactor, a filter, a sample barrel, a reference barrel, two water pumps, two refrigerators, two flow meters and a power supply. The multi-stage diaphragm electrochemical reactor has an anode chamber and a cathode chamber separated by a diaphragm, a rubber pad and a partition to prevent heat accumulation during the reaction process.

[0050] Preferably, a multi-stage diaphragm electrochemical reactor is equipped with multiple groups of electrode assemblies, diaphragms, rubber pads, partitions and bottom plates, and the electrode assemblies include a catalytically active anode and a corrosion-resistant cathode. Specifically, in a multi-stage diaphragm electrochemical reactor, the bottom plate is placed at the bottom layer, and the first partition and the anode plate are installed upward in sequence, and a rubber pad is placed between the first partition and the anode plate. A second partition is placed on the anode plate, and a diaphragm is arranged on the second partition. A third partition and a cathode plate are arranged upward on the diaphragm in sequence, and a rubber pad is also arranged between the third partition and the cathode plate. A fourth partition is arranged on the cathode plate, and so on, to form a multi-stage diaphragm electrochemical reactor.

[0051] Preferably, the multi-stage diaphragm electrochemical reactor is provided with a water inlet and outlet, a mud outlet, an exhaust port and a safety valve. The water outlet is mainly used to return the effluent after the reaction in the reactor to the sample barrel or the reference barrel, so as to circulate the effluent back to the multi-stage diaphragm electrochemical reactor for reaction again, so as to realize the internal circulation of the anode chamber and the cathode chamber. The main function of the safety valve is to automatically release the pressure when the pressure of the multi-stage diaphragm electrochemical reactor exceeds the maximum pressure it can withstand during the treatment of chromium-containing sulfuric acid waste liquid, so as to prevent the multi-stage diaphragm electrochemical reactor from being damaged or exploded; when the pressure of the multi-stage diaphragm electrochemical reactor increases abnormally due to a fault or other reasons, the safety valve will open and release part of the fluid, thereby protecting the entire reactor from pressure damage. The exhaust port is used to release the gas in the multi-stage diaphragm electrochemical reactor, and can also prevent the gas from forming air blockage in the multi-stage diaphragm electrochemical reactor, affecting the normal flow and treatment efficiency of the water flow. The mud outlet is used to discharge the suspended matter and colloidal particles generated during the wastewater treatment process from the reactor.

[0052] Preferably, the valves and pipes at the water inlet and outlet of the multi-stage electrochemical reactor are made of PP or UPVC.

[0053] Preferably, the present embodiment is further provided with a filter barrel, which is connected to the filter and is used to store unfiltered chromium-containing waste sulfuric acid.

[0054] In this embodiment, the filter is used to remove suspended matter such as particles, fibers, and graphite powder that may be contained in the chromium-containing waste sulfuric acid to prevent these suspended matter from affecting the efficiency of the electrolytic reaction or causing damage to the electrochemical reactor. These suspended matter can be removed by the filter, which is convenient for the subsequent electrolytic test, protects the electrolytic equipment from damage, and can also improve the treatment efficiency and treatment effect of the electrochemical reaction.

[0055] In this embodiment, the sample barrel is connected to the filter, and the sample barrel is used to store the chromium-containing sulfuric acid waste liquid filtered by the filter and the effluent of the anode area after the reaction of the multi-stage diaphragm electrochemical reactor.

[0056] In this embodiment, the reference barrel is connected to the filter, and the reference barrel is used to store the chromium-containing sulfuric acid waste liquid filtered by the filter and the effluent of the cathode area after the reaction of the multi-stage diaphragm electrochemical reactor.

[0057] In this embodiment, the water pump includes a first water pump and a second water pump, the first water pump is connected to the sample barrel, and the second water pump is connected to the reference barrel. The first water pump is used to transport the chromium-containing sulfuric acid waste liquid in the sample barrel into the first refrigerator; the second water pump is used to transport the chromium-containing sulfuric acid waste liquid in the reference barrel into the second refrigerator.

[0058] In this embodiment, the refrigerator includes a first refrigerator and a second refrigerator. The first refrigerator is connected to a first water pump, and the second refrigerator is connected to a second water pump. The water output after cooling by the refrigerator is transported to a multi-stage diaphragm electrochemical reactor to continue the reaction, thereby effectively avoiding the problem of low reaction efficiency and poor chromium regeneration and reuse effect caused by excessively high temperature.

[0059] In this embodiment, the flow meter includes a first flow meter and a second flow meter, the first flow meter is connected to the first refrigerator, the second flow meter is connected to the second refrigerator, and the first flow meter and the second flow meter are both connected to the multi-stage membrane electrochemical reactor. The flow meter is used to control the flow rate of the solution delivered to the multi-stage membrane electrochemical reactor so that the outflow and inflow flow rates of the solution in the multi-stage membrane electrochemical reactor are equal.

[0060] In this embodiment, the power source is connected to the multi-stage diaphragm electrochemical reactor.

[0061] In one embodiment, the diaphragm is a special diaphragm. A special diaphragm refers to a high-performance diaphragm used in a specific application. The special diaphragm has good high temperature resistance and can remain stable in a high temperature environment. The special diaphragm is more stable in chemical properties and is not easy to react with the electrolyte, thereby extending the service life of the electrode. The special diaphragm has excellent ion transfer performance and can provide lower ion transfer resistance. In the present invention, a special diaphragm is selected as the diaphragm in a multi-stage diaphragm electrochemical reactor to improve the reaction efficiency and product purity. The special diaphragm can better control the reaction conditions, improve the efficiency and selectivity of the reaction, realize the internal circulation of the two chambers of the anode chamber and the cathode chamber, prevent the heat accumulation caused by the reactor, and effectively avoid the problem of reduced electrochemical reaction efficiency or shortened electrode life due to excessive temperature.

[0062] In one embodiment, the refrigerator is a low-temperature constant bath device, and the refrigerator is used to exchange heat for the outlet water after the reaction in the multi-stage diaphragm electrochemical reactor. The low-temperature constant bath device is a commonly used device in laboratories and industrial fields for maintaining a low-temperature environment. The low-temperature constant bath device has a good refrigeration effect and can achieve high-precision temperature control, small temperature fluctuations, and high stability, which helps to improve the reaction efficiency and product purity. By using a low-temperature constant bath device for heat exchange, the temperature of the outlet water after the reaction can be effectively controlled to prevent the temperature in the reactor from being too high and reducing the subsequent reaction efficiency, resulting in poor regeneration and reuse of chromium, ensuring the stability and efficiency of the subsequent treatment process, while improving the safety and economy of the entire system.

[0063] In one embodiment, the inter-electrode spacing between the electrode assemblies in the multi-stage membrane electrochemical reactor is equal. Maintaining equal inter-electrode spacing between the electrode assemblies can ensure uniform current distribution throughout the reactor, thereby improving reaction efficiency and selectivity. In addition, mass transfer efficiency can be optimized, reactor stability can be improved, and safety can be enhanced because uniform inter-electrode spacing helps reduce the risk of overheating or runaway reactions.

[0064] In one embodiment, the inter-electrode distance ranges from 5 to 30 mm.

[0065] In one embodiment, the anode plate of the multi-stage diaphragm electrochemical reactor is a titanium-based lead dioxide anode plate, and the cathode plate of the multi-stage diaphragm electrochemical reactor is a lead cathode plate. The lead dioxide anode has good catalytic activity in the oxidation reaction, can effectively oxidize trivalent chromium to hexavalent chromium, improve the conversion efficiency, can selectively treat trivalent chromium under controlled conditions, reduce the interference of other metal ions in the wastewater, ensure the treatment effect, and can adjust the reaction conditions to adapt to waste sulfuric acid of different concentrations and compositions, thereby enhancing the adaptability of the system.

[0066] In one embodiment, the staged membrane electrochemical reactor has fixing nuts for fixing the anode plate, the cathode plate, the diaphragm and the separator.

[0067] In a preferred embodiment, the material of the fixing nut is one of PP or UPVC. In an electrochemical reactor, the material selection of the electrode fixing nut is crucial to the stability and safety of the equipment. Both UPVC and PP have the characteristics of high corrosion resistance, good corrosion resistance to most acids, alkalis and salts, and are suitable for use in chemical and wastewater treatment equipment (such as the reactor described in the present invention). In addition, UPVC and PP are light in weight, easy to transport and install, and their cost is relatively low, making them economical and practical materials. In the present invention, a fixing nut of PP or UPVC can be selected according to the actual application situation. For example, if higher heat resistance and electrical insulation are required, a fixing nut made of PP material is selected; and if better corrosion resistance and aging resistance are required, a fixing nut made of UPVC material is selected.

[0068] In one embodiment, the water pump is a centrifugal magnetic pump.

[0069] It should be noted that the centrifugal magnetic pump is a pump that uses the principle of magnetic transmission to achieve power transmission. It combines the advantages of centrifugal pumps and magnetic drive technology. The core part of the centrifugal magnetic pump consists of two magnetic drives: an inner magnetic rotor and an outer magnetic rotor. When the motor drives the outer magnetic rotor to rotate, due to the interaction of the magnetic field, the inner magnetic rotor will also rotate, and the inner magnetic rotor is connected to the impeller, thereby driving the impeller to rotate and transport the liquid. During the whole process, due to the presence of the magnetic drive, the inner and outer parts of the pump are completely isolated, achieving a completely sealed effect. In the present invention, the chromium-containing sulfuric acid waste liquid in the reference barrel and the sample barrel are pumped into two refrigerators respectively through two centrifugal magnetic pumps. The leakage-free design of the centrifugal magnetic pump reduces the risk of leakage of harmful waste liquid, improves the safety of operation, and prevents environmental pollution caused by leakage of waste liquid. At the same time, the high-efficiency transmission of the centrifugal magnetic pump helps to improve the efficiency of waste liquid treatment and reduce energy consumption. In addition, the structural design of the centrifugal magnetic pump reduces the maintenance workload and reduces long-term operating costs.

[0070] The present invention also provides a method for regenerating and reusing chromium-containing sulfuric acid waste liquid. The method is implemented based on the regenerating and reusing device for treating chromium-containing sulfuric acid waste liquid described in the present invention. The method comprises the following steps:

[0071] (1) The chromium-containing sulfuric acid waste liquid is transported to a filter for filtering to remove impurities such as suspended matter and particulate matter in the chromium-containing sulfuric acid waste liquid.

[0072] (2) The chromium-containing sulfuric acid waste liquid filtered by the filter in step (1) is transferred to the sample barrel and the reference barrel until the water levels in the sample barrel and the reference barrel are consistent.

[0073] (3) The chromium-containing sulfuric acid waste liquid in the sample barrel and the reference barrel is transported to a graded membrane electrochemical reactor for reaction.

[0074] It should be noted that when step (3) is performed, the valves at the water inlet and outlet of the graded membrane electrochemical reactor are opened, and the water pump is turned on at the same time, and the corresponding valves of the flowmeter are adjusted to control the flow rate, so that the flow rate of the solution flowing into the anode chamber of the reactor is equal to the flow rate flowing out, and the flow rate of the solution flowing into the cathode chamber of the reactor is equal to the flow rate flowing out.

[0075] (4) Under the action of the electric field, a large number of free radicals and ions are generated on the surface of the anode plate, so that the trivalent chromium in the anode chamber is oxidized to hexavalent chromium by the free radicals and ions; and the hexavalent chromium in the cathode chamber is reduced to trivalent chromium.

[0076] It should be noted that multiple sets of special diaphragms can effectively hinder the diffusion of hexavalent chromium (Cr(VI)) from the anode chamber to the cathode chamber. More Cr(VI) can be preserved in the anode chamber, and the waste acid solution after the reaction in the anode area flows out from the outlet of the anode chamber and flows back into the sample barrel, forming a circulation in the anode chamber.

[0077] It should be noted that under the action of the electric field, the hexavalent chromium in the cathode chamber is reduced to trivalent chromium (Cr(III)). Since the initial concentrations of the anode chamber and the cathode chamber are the same, when the trivalent chromium concentration in the anode chamber is gradually oxidized to hexavalent chromium, a concentration difference appears in the trivalent chromium in the anode chamber and the cathode chamber, accelerating the diffusion of trivalent chromium to the anode area. The anode has a repulsive effect on the trivalent chromium positive group, so the electrostatic repulsion and the driving force of the concentration difference form an antagonism, inhibiting some trivalent chromium from diffusing into the anode chamber. In addition, part of the hexavalent chromium diffused to the cathode chamber will be reduced to trivalent chromium, and the trivalent chromium in the cathode chamber will gradually increase. The waste acid solution after the reaction in the cathode area flows out from the cathode chamber outlet and flows back to the reference barrel, forming a circulation in the cathode chamber.

[0078] Preferably, during the reaction process of step (4), the current is controlled in the range of 100 to 900 A.

[0079] (5) The effluent in the anode chamber after the reaction in step (4) is transported to the sample bucket; the effluent in the cathode chamber after the reaction in step (4) is transported to the reference bucket.

[0080] (6) The water from the sample barrel in step (5) is pumped to a refrigerator for heat exchange, and the water after heat exchange is again pumped to the graded membrane electrochemical reactor for reaction to form a circulation in the anode chamber; the water from the reference barrel in step (5) is pumped to a refrigerator for heat exchange, and the water after heat exchange is again pumped to the graded membrane electrochemical reactor for reaction to form a circulation in the cathode chamber.

[0081] It is worth noting that before electrolysis, the refrigerator needs to be turned on in advance and run for a period of time in advance. The electrolysis reaction can only be started after the refrigerator is iced out and kept at a low temperature. Preferably, during the refrigeration process of the refrigerator, a certain volume of a solution containing 5% to 10% sodium chloride is added, and the solution is mechanically stirred or mixed in advance to dissolve all the sodium chloride, so as to achieve better refrigeration.

[0082] In summary, the regeneration and reuse treatment device and method of the chromium-containing sulfuric acid waste liquid described in the present invention, through the graded membrane structure in the graded membrane electrochemical reactor, the chromium-containing sulfuric acid waste liquid enters the reactor reaction process, the trivalent chromium in the anode area is oxidized to hexavalent chromium, and the hexavalent chromium in the cathode area is reduced to trivalent chromium. The diaphragm prevents the diffusion of the hexavalent chromium in the anode area, and the trivalent chromium and hexavalent chromium are concentrated in the valence state, which greatly improves the resource utilization efficiency. At the same time, the effluent of the graded membrane electrochemical reactor after the reaction flows back to the sample barrel and the reference barrel, and is re-input into the graded membrane electrochemical reactor through the refrigerator to react again, forming a circulation in the anode chamber and a circulation in the cathode chamber, effectively extending the service life of the electrode and preventing the electrochemical reaction efficiency from being reduced due to excessive temperature. In this process, the reaction can be easily cooled by the refrigerator to avoid the reduction of the electrolytic reaction efficiency due to excessive temperature, and the regeneration and reuse effect of chromium is guaranteed.

[0083] In a specific embodiment, the electrolyte acid concentration is 13wt.%, the total chromium concentration is 1942mg / L, and the electrolysis is carried out for 12 hours under a constant current of 400A. The Cr(VI) regeneration amount and regeneration rate obtained from the sample barrel and the anode outlet are significantly higher than those from the reference barrel and the cathode outlet, which further illustrates that in the electrolysis test, the anode oxidizes Cr(III) to Cr(VI), and at the same time, the cathode has a reducing effect on the generated Cr(VI), which will further reduce it to Cr(III), so the Cr(VI) content in the reference barrel and the cathode outlet is very small. After 12 hours of reaction, the Cr(VI) regeneration rate is as high as 54.18%.

[0084] In another specific embodiment, the electrolyte acid concentration is 21wt.%, the total chromium concentration is 3246mg / L, the current is 400A, and the electrolysis is performed for 12 hours. In the first 6 hours of the reaction, the Cr(VI) regeneration rates at the sample barrel and the anode outlet are 41% and 44.17%, respectively. This stage can maintain a relatively stable Cr(VI) regeneration effect, and the reaction rate gradually tends to be flat from 7 to 12 hours. During the reaction, the maximum Cr(VI) regeneration rates at the sample barrel and the anode outlet are 51.05% and 55.62%, respectively. The results show that the Cr(VI) regeneration rate decreases slightly with the increase of acid concentration.

[0085] In other specific embodiments, the electrolyte acid concentration is 21wt.%, the total chromium concentration is 3246mg / L, and the current is 400A, and the electrolysis is performed for 12 hours. Then the current is increased to 600A, and the electrolysis test is continued for 12 hours. As the current increases, the Cr(VI) regeneration effect is significantly improved. After 5 hours of constant current reaction at 600A, the Cr(VI) regeneration rate in the sample barrel is 80.10%, which is about 25.92% higher than the Cr(VI) regeneration rate at constant current 400A. After 11 hours of constant current reaction at 600A, the highest Cr(VI) regeneration rate is 93.97%. The specific actual test parameters are shown in the following table:

[0086] Table 1 Actual test parameters

[0087]

[0088]

[0089] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Therefore, any modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A device for regenerating and reusing chromium-containing sulfuric acid waste liquid, characterized in that: include: Multi-stage diaphragm electrochemical reactor; Filters; A sample barrel, the sample barrel is connected to the filter, and the sample barrel is used to store the chromium-containing sulfuric acid waste liquid filtered by the filter and the effluent of the anode area after the reaction of the multi-stage diaphragm electrochemical reactor; A reference barrel, the reference barrel is connected to the filter, and the reference barrel is used to store the chromium-containing sulfuric acid waste liquid filtered by the filter and the effluent of the cathode area after the reaction of the multi-stage diaphragm electrochemical reactor; A water pump, the water pump comprising a first water pump and a second water pump, the first water pump being connected to the sample barrel, and the second water pump being connected to the reference barrel; A refrigerator, the refrigerator comprising a first refrigerator and a second refrigerator, the first refrigerator is connected to the first water pump, and the second refrigerator is connected to the second water pump; A flow meter, the flow meter comprising a first flow meter and a second flow meter, the first flow meter is connected to a first refrigerator, the second flow meter is connected to a second refrigerator, and the first flow meter and the second flow meter are both connected to the multi-stage membrane electrochemical reactor; A power source connected to the multi-stage diaphragm electrochemical reactor; The multi-stage membrane electrochemical reactor has an anode chamber and a cathode chamber separated by a membrane, a rubber pad and a partition to prevent heat accumulation during the reaction process.

2. The device for regenerating and reusing chromium-containing sulfuric acid waste liquid according to claim 1, characterized in that: The diaphragm is a special diaphragm.

3. The regeneration and reuse treatment device for chromium-containing sulfuric acid waste liquid according to claim 1, characterized in that: The refrigerator is a low-temperature constant bath device, and the refrigerator is used to perform heat exchange on the outlet water after the reaction in the multi-stage diaphragm electrochemical reactor.

4. The device for regenerating and reusing chromium-containing sulfuric acid waste liquid according to claim 1, characterized in that: The inter-electrode distances between the electrode assemblies in the multi-stage membrane electrochemical reactor are equal.

5. The device for regenerating and reusing chromium-containing sulfuric acid waste liquid according to claim 4, characterized in that: The inter-electrode distance ranges from 5 to 30 mm.

6. The device for regenerating and reusing chromium-containing sulfuric acid waste liquid according to claim 1, characterized in that: The anode plate of the multi-stage diaphragm electrochemical reactor is a titanium-based lead dioxide anode plate, and the cathode plate of the multi-stage diaphragm electrochemical reactor is a lead cathode plate.

7. The device for regenerating and reusing chromium-containing sulfuric acid waste liquid according to claim 6, characterized in that: The staged membrane electrochemical reactor has fixing nuts for fixing the anode plate, cathode plate, diaphragm and separator.

8. The device for regenerating and reusing chromium-containing sulfuric acid waste liquid according to claim 6, characterized in that: The fixing nut is made of PP or UPVC.

9. The device for regenerating and reusing chromium-containing sulfuric acid waste liquid according to claim 1, characterized in that: The water pump is a centrifugal magnetic pump.

10. A method for regenerating and reusing chromium-containing sulfuric acid waste liquid, characterized in that: The method is realized based on the regeneration and reuse treatment device of the chromium-containing sulfuric acid waste liquid according to any one of claims 1 to 9, and comprises the following steps: (1) transporting the chromium-containing sulfuric acid waste liquid to a filter for filtering; (2) transferring the chromium-containing sulfuric acid waste liquid filtered by the filter in step (1) to a sample barrel and a reference barrel until the water levels in the sample barrel and the reference barrel are consistent; (3) transporting the chromium-containing sulfuric acid waste liquid in the sample barrel and the reference barrel to a graded membrane electrochemical reactor for reaction; (4) Under the action of the electric field, a large number of free radicals and ions are generated on the surface of the anode plate, so that the trivalent chromium in the anode chamber is oxidized to hexavalent chromium by the free radicals and ions; the hexavalent chromium in the cathode chamber is reduced to trivalent chromium; (5) transporting the effluent in the anode chamber after the reaction in step (4) to a sample bucket; transporting the effluent in the cathode chamber after the reaction in step (4) to a reference bucket; (6) The water outlet from the sample barrel in step (5) is transported to a refrigerator through a water pump for heat exchange, and the water outlet after heat exchange is transported to the graded membrane electrochemical reactor again for reaction to form a circulation in the anode chamber; the water outlet from the reference barrel in step (5) is transported to a refrigerator through a water pump for heat exchange, and the water outlet after heat exchange is transported to the graded membrane electrochemical reactor again for reaction to form a circulation in the cathode chamber.

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