Double-cathode electrochemical rinse tank structure

Abstract

The utility model provides a double-cathode electrochemical rinse tank structure, which belongs to the technical field of solar cells and comprises a rinse tank body, and a partition plate is arranged in the rinse tank body and divides the rinse tank body into a first cathode rinse area and a second cathode rinse area; a communicating gap is formed between the lower end of the partition plate and the tank bottom of the cleaning tank body and communicates with the first cathode cleaning area and the second cathode cleaning area. A first anode and a first cathode which are connected with a first power supply are arranged in the first cathode cleaning area and are used for generating hydrogen peroxide; a second anode and a second cathode which are connected with a second power supply are arranged in the second cathode cleaning area and are used for generating. OH; wherein the first cathode and the second cathode are arranged on two opposite surfaces of the partition plate in a back-to-back manner, and a through hole is formed in the partition plate. According to the utility model, the usage amount of dangerous chemicals can be reduced, the storage and transportation risks of hydrogen peroxide can be reduced, and the COD value in wastewater can also be reduced.

Description

TECHNICAL FIELD

[0001] The utility model belongs to solar cell technical field, concretely relates to a double cathode electrochemistry cleaning tank structure. BACKGROUND

[0002] At present, mainstream solar cells are crystalline silicon cells, and in the process of preparing the cells, a chemical pre-cleaning method is usually used to remove the damage layer on the surface of a silicon wafer and surface pollutants (organic and inorganic pollutants), however, the traditional chemical cleaning method needs to consume a large amount of hazardous chemicals, especially hydrogen peroxide which is poor in stability and is not conducive to storage and transportation, and the use of organic additives can reduce the amount of hydrogen peroxide used, but the use of additives will increase the COD value in the wastewater, and the wastewater discharge standard cannot meet the requirements of the environmental impact assessment and relevant environmental protection regulations, and the discharge of wastewater exceeding the standard will face the pressure of environmental impact assessment and production limitation, and the COD value in the wastewater needs to be treated subsequently, which will also increase the production cost, therefore, it is of great significance to develop a green silicon wafer cleaning technology. SUMMARY

[0003] The utility model embodiment provides a double cathode electrochemistry cleaning tank structure, aims at solving the problem that a large amount of hazardous chemicals are used at present, the COD value in the discharged wastewater exceeds the standard, the wastewater discharge standard is not met, and the cost generated by the pressure of environmental impact assessment and the treatment of wastewater not meeting the standard can also be reduced, and the risk of hydrogen peroxide storage and transportation can be reduced.

[0004] To achieve the above-mentioned purpose, the utility model adopts the technical scheme of providing a double cathode electrochemistry cleaning tank structure, comprising: a cleaning tank body, a partition plate is arranged in the cleaning tank body, the partition plate divides the cleaning tank body into a first cathode cleaning area and a second cathode cleaning area, a communication gap is arranged between the lower end of the partition plate and the tank bottom of the cleaning tank body, and the communication gap communicates the first cathode cleaning area and the second cathode cleaning area.

[0005] A first anode and a first cathode connected with a first power supply are arranged in the first cathode cleaning area, and are used for generating hydrogen peroxide, and a second anode and a second cathode connected with a second power supply are arranged in the second cathode cleaning area, and are used for generating ·OH.

[0006] The first cathode and the second cathode are arranged back to back on the two opposite surfaces of the partition plate, and a through hole is arranged on the partition plate.

[0007] In an implementable mode, the first cathode and the second cathode respectively fully or partially cover the corresponding surfaces of the partition plate, and the through hole penetrates the first cathode and the second cathode.

[0008] In an implementable mode, the first cathode is a CF electrode or a GF electrode; the second cathode is an iron-based or cobalt-based coated CF electrode; and the first anode or the second anode is a Pt electrode or a graphite electrode.

[0009] In an implementable mode, the shape of the through hole is any one or a combination of multiple polygons.

[0010] In an implementable mode, the cleaning tank body is provided with a limiting groove on each of the two sides of the partition plate, and a limiting baffle is arranged at the lower end of the limiting groove; the partition plate is inserted into the limiting groove, and the lower end abuts against the limiting baffle.

[0011] In an implementable mode, the bottom of the cleaning tank body is paved with a liquid bubbling pipeline and a gas bubbling pipeline; the liquid bubbling pipeline is partially located in the first cathode cleaning area and partially located in the second cathode cleaning area; and the gas bubbling pipeline is partially located in the first cathode cleaning area and partially located in the second cathode cleaning area.

[0012] In an implementable mode, the liquid bubbling pipeline is located below the gas bubbling pipeline, and the liquid bubbling pipeline and the gas bubbling pipeline are vertically arranged or staggered.

[0013] In an implementable mode, the gas bubbling pipeline is uniformly provided with a plurality of exhaust holes along the length direction.

[0014] In an implementable mode, the distance from the communication gap to the highest point of the gas bubbling pipeline is 5-10 cm.

[0015] In an implementable mode, the first anode and the second anode are respectively arranged in the cleaning tank body and parallel to the two sides of the partition plate.

[0016] Compared with the prior art, the double-cathode electrochemical cleaning tank structure has the beneficial effects that: the first cathode cleaning area can utilize oxygen in air to realize selective oxygen reduction reaction, prepare a large amount of hydrogen peroxide, and reduce or eliminate the need for external hydrogen peroxide, thereby reducing the risk of hydrogen peroxide in transportation and storage; directly utilizing oxygen in air to obtain hydrogen peroxide can reduce the use amount of hydrogen peroxide, reduce the use of a large amount of organic additives, thereby reducing the waste COD value and alleviating the environmental impact assessment pressure; the generated wastewater can be directly discharged, without the need for COD treatment, and the production cost is also reduced; the hydrogen peroxide prepared by the first cathode reaction can directly enter the second cathode cleaning area through the through hole on the partition plate to generate ·OH, and the ·OH and the hydrogen peroxide that has not reacted in time are used to efficiently oxidize the surface of the silicon wafer and further react with the alkali solution to achieve the purpose of pre-cleaning.

[0017] The application adopts a double-cathode electrochemical oxidation cleaning method, compared with the traditional hydrogen peroxide+alkali+additive method, can save a large amount of chemical use, can reduce the risk of hydrogen peroxide in transportation and storage, reduce the environmental evaluation pressure, and has very important significance for realizing green cleaning. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A structure schematic view of a double-cathode electrochemical cleaning tank structure provided by the embodiment of the utility model is provided;

[0019] Figure 2 A structure schematic view of a first cathode, a second cathode and a partition plate provided by the embodiment of the utility model is provided;

[0020] Figure 3 A structure schematic view of a partition plate provided by the embodiment of the utility model is provided;

[0021] Figure 4 A structure schematic view of an exhaust hole on a gas bubbling pipeline provided by the embodiment of the utility model is provided;

[0022] BRIEF DESCRIPTION OF DRAWINGS

[0023] 1, air compressor; 2, rotor flowmeter; 3, first anode; 4, first power supply; 5, first cathode; 6, partition plate; 7, second cathode; 8, second anode; 9, second power supply; 10, liquid bubbling pipeline; 11, gas bubbling pipeline; 12, cleaning tank body; 13, through hole; 14, exhaust hole. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical schemes and beneficial effects to be solved by the utility model more clear and apparent, the utility model is further described in detail below by combining with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model, and are not used to limit the utility model.

[0025] Please refer to Figures 1 to 4The utility model provides a double cathode electrochemistry cleaning tank structure, and compared with the prior art, has the beneficial effect that: the first cathode cleaning area can realize selective oxygen reduction reaction by oxygen in air, and a large amount of hydrogen peroxide is prepared, so that the additional hydrogen peroxide can be reduced or not used, thereby reducing the risk of hydrogen peroxide in transportation and storage; the hydrogen peroxide obtained directly by using oxygen in air can be directly used, so that the use amount of hydrogen peroxide can be reduced, a large amount of organic additives can be reduced, thereby reducing the waste COD value and alleviating the environmental impact assessment pressure; the generated wastewater can be directly discharged, and the COD in the wastewater does not need to be treated, thereby reducing the production cost; the hydrogen peroxide prepared by the reaction of the first cathode 5 can directly enter the second cathode cleaning area through the through hole on the partition plate 6 to generate ·OH, and the ·OH and the hydrogen peroxide which does not react in time are used to efficiently oxidize the surface of the silicon wafer and further react with the alkali solution to achieve the purpose of pre-cleaning.

[0026] The utility model provides a double cathode electrochemistry cleaning tank structure, and compared with the prior art, has the beneficial effect that: the first cathode cleaning area can realize selective oxygen reduction reaction by oxygen in air, and a large amount of hydrogen peroxide is prepared, so that the additional hydrogen peroxide can be reduced or not used, thereby reducing the risk of hydrogen peroxide in transportation and storage; the hydrogen peroxide obtained directly by using oxygen in air can be directly used, so that the use amount of hydrogen peroxide can be reduced, a large amount of organic additives can be reduced, thereby reducing the waste COD value and alleviating the environmental impact assessment pressure; the generated wastewater can be directly discharged, and the COD in the wastewater does not need to be treated, thereby reducing the production cost; the hydrogen peroxide prepared by the reaction of the first cathode 5 can directly enter the second cathode cleaning area through the through hole on the partition plate 6 to generate ·OH, and the ·OH and the hydrogen peroxide which does not react in time are used to efficiently oxidize the surface of the silicon wafer and further react with the alkali solution to achieve the purpose of pre-cleaning.

[0027] COD (Chemical Oxygen Demand) is an important index for measuring the content of organic matter in water, which represents the amount of oxygen consumed by oxidizing organic matter in water samples under certain conditions with strong oxidizing agents (such as potassium dichromate or potassium permanganate), and the unit is mg / L. COD is an important index for evaluating organic pollution in water, and wastewater with COD exceeding the standard cannot be directly discharged.

[0028] The application adopts a double cathode electrochemical oxidation cleaning tank structure, which can save a large amount of chemicals compared with the traditional single cathode tank of hydrogen peroxide + alkali + additives, can reduce the risk of hydrogen peroxide in transportation and storage, and can also reduce the environmental impact assessment pressure, which has great significance for realizing green cleaning.

[0029] In actual application, the utilization rate of hydrogen peroxide in the single cathode tank structure is low, and there is a risk of excessive or insufficient oxidation, and the double cathode electrochemical cleaning tank proposed by the application can essentially solve this series of problems.

[0030] The present application divides the cleaning tank 12 into two cleaning zones by the partition 6, and each cleaning zone is provided with a cathode and a power supply. Oxygen in the air is reduced to an oxidation source by two-step electrochemical reduction in the two cleaning zones, so as to realize preparation of the oxidation source required by the cleaning tank.

[0031] In the first step, the oxygen in the air is selectively subjected to two-electron oxygen reduction reaction to generate hydrogen peroxide in the first cathode cleaning zone by the electrochemical oxygen reduction method (reaction equation: O2+2e - +2H+→H2O2or O2+2e - +2H2O→H2O2+2OH - );

[0032] In the second step, hydrogen peroxide is subjected to non-selective reaction to generate ·OH in the second cathode cleaning zone (reaction equation: M n+ + H2O2+xH + →M m+ + H2O +·OHor H2O2+2e - →2·OH), and then ·OH and hydrogen peroxide which is not reacted in time are used to efficiently oxidize the surface of the silicon wafer and further react with the alkali solution to achieve the purpose of cleaning.

[0033] Possible reaction equations are shown in equations (1)-(6):

[0034] H2O2+•OH→•OOH+ H2O (1)

[0035] •OH+•OH→ H2O2 (2)

[0036] 2·OH+Si→SiO2+ H2O (3)

[0037] 2 H2O2+Si→SiO2+ H2O (4)

[0038] OR+·OH→CO2+ H2O +small molecule inorganic (5)

[0039] OR+ H2O2→CO2+ H2O +small molecule inorganic (6)

[0040] Among them, reaction equation (3) and reaction equation (4) are the oxidation process of the surface of the silicon wafer, and through the reaction, the particles on the surface of the silicon wafer are removed, and with the subsequent oxide being washed away, the metal ions coated in the oxide are removed; reaction equation (5) and reaction equation (6) are reaction equations for washing the organic matter on the surface of the silicon wafer and diffusing into the solution, mainly reaction equation (6), and reaction generates carbon dioxide, water and small molecule inorganic matter, which can reduce the COD value in the wastewater.

[0041] The double-cathode electrochemical cleaning tank structure provided in the application is controlled by two power sources, and corresponds to reaction formula (3) and reaction formula (4) respectively. The power source can be adjusted according to the requirement of oxidizability in the cleaning tank body 12. Generally, in the initial cleaning stage, in order to remove the organic matter on the surface of the silicon wafer and quickly oxidize the surface damage layer, the second power source 9 for controlling the generation of ·OH of the second cathode 7 is turned on (10-120 s / batch), and then the ratio of hydrogen peroxide to ·OH is controlled by the opening time of the second power source 9, so as to realize the cleaning of the surface of the silicon wafer and obtain a better surface. In the second step reaction, due to the back-to-back arrangement of the two cathodes, the hydrogen peroxide contacts the second cathode 7 through the through hole in the shortest distance and time. Therefore, the design of the double-power double-cathode promotes the further conversion reaction of the oxygen reduction reaction and the hydrogen peroxide to move to the right, improves the oxygen reduction efficiency and the utilization rate of the hydrogen peroxide, and adjusts the ratio of the hydrogen peroxide to ·OH according to the requirement.

[0042] In some embodiments, referring to Figure 1 and Figure 2 , the first cathode 5 and the second cathode 7 are respectively or partially covered with the surface corresponding to the baffle 6, and the through hole 13 penetrates the first cathode 5 and the second cathode 7. Due to the back-to-back arrangement of the two cathodes, the hydrogen peroxide contacts the second cathode 7 through the through hole in the shortest distance and time. This design of the double-power double-cathode promotes the further conversion reaction of the oxygen reduction reaction and the hydrogen peroxide, and accelerates the movement to the right through the through hole, improves the oxygen reduction efficiency and the utilization rate of the hydrogen peroxide, and adjusts the ratio of the hydrogen peroxide to ·OH according to the requirement.

[0043] Regarding the explanation of being covered or partially covered, for example, when the length and width of the first cathode 5 are consistent with the length and width of the baffle 6, the first cathode 5 covers the surface of the baffle 6; when the width of the first cathode 5 is smaller than the width of the baffle 6, the first cathode 5 partially covers the surface of the baffle 6.

[0044] The above explanation of accelerating the movement to the right is an example of the illustration. The first cathode cleaning area is on the left side of the second cathode cleaning area, and the hydrogen peroxide generated near the first cathode 5 moves to the right through the through hole and contacts the second cathode 7 for reaction.

[0045] In some embodiments, referring to Figure 1, the first cathode 5 is a CF electrode or a GF electrode; the second cathode 7 is an iron-based or cobalt-based coated CF electrode, and the first anode 3 or the second anode 8 is a Pt electrode or a graphite electrode. Specifically, the material used for the first cathode 5 needs to have a high specific surface area, excellent gas adsorption performance, as many oxygen vacancies as possible, and strong acid and alkali resistance, so CF, GF and related modified electrode materials with extremely strong stability are selected; the electrode material of the second cathode 7 needs to have the ability to react with hydrogen peroxide and also needs to have strong stability, so an ordinary CF, GF electrode and its non-metal modified electrode can be selected, and the electrode material of the first anode 3 and the second anode 8 is selected from high-stability conventional anode materials such as Pt and graphite.

[0046] Explanation: CF electrode (Calomel Electrode, Calomel electrode), composition: composed of mercury, calomel (Hg2Cl2) and potassium chloride solution. GF electrode (Glass Electrode, glass electrode), composition: made of special glass film.

[0047] In some embodiments, referring to Figure 3 The shape of the through hole 13 is circular or any one or a combination of multiple polygons. The material of the partition plate 6 is the same as that of the cleaning tank body 12, limiting grooves are arranged on the opposite sides of the cleaning tank body 12, limiting stop plates are arranged at the lower ends of the limiting grooves, the partition plate 6 is inserted along the limiting grooves, and the lower end of the partition plate 6 contacts the limiting stop plate. The limiting stop plate can control the width of the communication gap between the partition plate 6 and the bottom of the cleaning tank body 12.

[0048] The through holes 13 are arranged in an array on the partition plate 6, the through holes 13 can be a combination of circular holes and triangular holes, a combination of triangular holes and pentagonal holes, or all circular holes or rectangular holes, which will not be listed one by one here.

[0049] In some embodiments, referring to Figure 1 The bottom of the cleaning tank body 12 is paved with a liquid bubbling pipeline 10 and a gas bubbling pipeline 11, the liquid bubbling pipeline 10 is partially located in the first cathode cleaning area and partially located in the second cathode cleaning area; the gas bubbling pipeline 11 is partially located in the first cathode cleaning area and partially located in the second cathode cleaning area. Bubbling can make the liquid in the cleaning tank body 12 uniform and accelerate the reaction speed, thereby improving the cleaning effect.

[0050] The liquid bubbling pipeline 10 and the gas bubbling pipeline 11 are made of acid and alkali corrosion resistant materials. For example, plastic pipes such as polyvinyl chloride (PVC) pipe, polypropylene (PP) pipe, polyvinylidene fluoride (PVDF) pipe, and polytetrafluoroethylene (PTFE) pipe; and glass fiber reinforced plastic pipes such as epoxy resin glass fiber reinforced plastic pipe and phenolic resin glass fiber reinforced plastic pipe.

[0051] In some embodiments, referring to Figure 1 , the liquid bubbling pipeline 10 is located below the gas bubbling pipeline 11, and the liquid bubbling pipeline 10 and the gas bubbling pipeline 11 are vertically arranged or staggered to avoid interference and affect the bubbling effect.

[0052] In some embodiments, referring to Figure 4 , the gas bubbling pipeline 11 is uniformly provided with a plurality of air vents 14 along the length direction. For example, the air vents 14 are arranged at the highest point of the gas bubbling pipeline 11.

[0053] In some embodiments, referring to Figure 4 , the gas bubbling pipeline 11 is provided with two rows of air vents 14 along the length direction, and the two rows of air vents 14 are symmetrically arranged on both sides of the gas bubbling pipeline 11. For example, the air vents 14 are arranged at a 45° position on both sides of the gas bubbling pipeline 11, and the diameter is 0.1-1mm.

[0054] In this application, the gas bubbling pipeline 11 includes a plurality of gas bubbling branch pipes parallelly laid on the bottom of the cleaning tank 12, and the distance between two adjacent gas bubbling branch pipes is 0.5-1cm; the gas bubbling pipeline 11 is connected with a rotor flowmeter 2 with an oxygen content sensor and an air compressor 1, and when the dissolved oxygen content in the liquid in the cleaning tank 12 is lower than 1%, the rotor flowmeter 2 is opened to control the gas flow to be 20ml / min-100ml / min to bubble into the cleaning tank 12. In order to avoid useless work of the compressor, when the dissolved oxygen content in the liquid is higher than 3%, the rotor flowmeter 2 is closed, and the air compressor 1 stops working.

[0055] In this application, the liquid bubbling pipeline 10 is provided with a plurality of liquid vents, which can be arranged in the same way as the air vents 14.

[0056] The liquid bubbling pipeline 10 includes a plurality of liquid bubbling branch pipes parallelly laid on the bottom of the cleaning tank 12, and the liquid bubbling branch pipes are perpendicular to the gas bubbling branch pipes. The liquid bubbling pipeline 10 and the gas bubbling pipeline 11 can also be arranged in a bent manner.

[0057] In some embodiments, referring to Figure 1 , the distance from the communication gap to the highest point of the gas bubbling pipeline 11 is 5-10cm, so that the liquid in the cleaning tank 12 can flow smoothly.

[0058] In some embodiments, referring to Figure 1 The first anode 3 and the second anode 8 are arranged in the cleaning tank 12 respectively on two sides parallel to the partition plate 6. The first power supply 4 and the second power supply 9 are arranged on the side of the cleaning tank 12 perpendicular to the partition plate 6, and the wires wrapped with acid-alkali-oxidation-resistant material connect the corresponding anode, cathode and power supply. Meanwhile, the power supply should be provided with hydrogen peroxide and ·OH sensors to control the opening time of the second power supply 9 according to the oxidation strength.

[0059] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described or recorded in a certain embodiment can be referred to the related description of other embodiments.

[0060] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A dual cathode electrochemical cleaning cell structure, characterized by, The application relates to a cleaning tank body (12) provided with a partition plate (6) inside the cleaning tank body (12), the partition plate (6) separates the cleaning tank body (12) into a first cathode cleaning area and a second cathode cleaning area; a communication gap is arranged between the lower end of the partition plate (6) and the tank bottom of the cleaning tank body (12), and the first cathode cleaning area and the second cathode cleaning area are communicated. A first anode (3) and a first cathode (5) connected with a first power supply (4) are arranged in the first cathode cleaning area and used for generating hydrogen peroxide; a second anode (8) and a second cathode (7) connected with a second power supply (9) are arranged in the second cathode cleaning area and used for generating ·OH. The first cathode (5) and the second cathode (7) are arranged on the opposite surfaces of the partition plate (6) in a back-to-back mode, and the partition plate (6) is provided with a through hole (13). The first cathode (5) and the second cathode (7) respectively fully or partially cover the corresponding surfaces of the partition plate (6), and the through hole (13) penetrates the first cathode (5) and the second cathode (7).

2. The dual cathode electrochemical cleaning cell structure of claim 1, wherein, The first cathode (5) is a CF electrode or a GF electrode; the second cathode (7) is a CF electrode coated with iron or cobalt; and the first anode (3) or the second anode (8) is a Pt electrode or a graphite electrode.

3. The dual cathode electrochemical cleaning cell structure of claim 1, wherein, The shape of the through hole (13) is any one or a combination of multiple polygons.

4. The dual cathode electrochemical cleaning cell structure of claim 1, wherein, The cleaning tank body (12) is provided with a limiting groove on each of the two side surfaces perpendicular to the partition plate (6), the lower end of the limiting groove is provided with a limiting baffle, the partition plate (6) is inserted into the limiting groove, and the lower end abuts against the limiting baffle.

5. The dual cathode electrochemical cleaning cell structure of claim 1, wherein, The bottom of the cleaning tank body (12) is paved with a liquid bubbling pipeline (10) and a gas bubbling pipeline (11), the liquid bubbling pipeline (10) is partially located in the first cathode cleaning area and partially located in the second cathode cleaning area; and the gas bubbling pipeline (11) is partially located in the first cathode cleaning area and partially located in the second cathode cleaning area.

6. The dual cathode electrochemical cleaning cell structure of claim 1, wherein, The liquid bubbling pipeline (10) is located below the gas bubbling pipeline (11), and the liquid bubbling pipeline (10) and the gas bubbling pipeline (11) are vertically arranged or staggered arranged.

7. The dual cathode electrochemical cleaning cell structure of claim 6, wherein, The gas bubbling pipeline (11) is uniformly provided with a plurality of air holes (14) along the length direction.

8. The dual cathode electrochemical cleaning cell structure of claim 6, wherein, The distance from the communication gap to the highest point of the gas bubbling pipeline (11) is 5-10 cm.

9. The dual cathode electrochemical cleaning cell structure of claim 7, wherein, The first anode (3) and the second anode (8) are respectively arranged on the two side surfaces of the cleaning tank body (12) and parallel to the partition plate (6).

10. The dual cathode electrochemical cleaning cell structure of claim 1, wherein, ​

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