CN215415178U - Portable COD rapid determination appearance is with disposable integrated electrode unit - Google Patents
Portable COD rapid determination appearance is with disposable integrated electrode unit Download PDFInfo
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Abstract
The utility model relates to a disposable integrated electrode unit for a portable COD rapid determinator, which is characterized by comprising a working electrode, a counter electrode, a reaction tank and a tank sleeve, wherein the working electrode is a single-sided PCB copper-clad substrate, and a copper foil surface connected with the reaction tank end is additionally provided with screen printing PbO2The counter electrode is a rectangular plate body with a single-sided PCB copper-clad substrate copper foil surface connected with a reaction pool end and an Ag coating added by screen printing; the reaction tank is a square body and is provided with a front part penetrating through the tank body,A pool liquid inlet pore channel is vertically arranged in the middle of the rear cylindrical reaction cavity; the square body is matched with the working electrode and the counter electrode and is provided with a front dustpan-shaped groove and a rear dustpan-shaped groove with openings on the left sides; the working electrode and the counter electrode are oppositely and respectively sealed and cover the front and rear ports of the reaction cavity and are embedded into the front and rear dustpan-shaped grooves; the pool cover is a square sleeve, the reaction pool is tightly attached to the wall of the square sleeve and is embedded into the sleeve, and a sleeve liquid inlet hole is formed in the top surface of the square sleeve and aligned with the pool liquid inlet pore passage. Has the advantages that: small size, high repeatability, high speed and high accuracy.
Description
Technical Field
The utility model relates to the technical field of water quality Chemical Oxygen Demand (COD) (chemical Oxygen demand) detection, in particular to a disposable integrated electrode unit for a portable COD rapid determinator.
Background
Chemical Oxygen Demand (COD) is the amount of oxidant consumed when a strong oxidant is used to oxidize reducing substances in a water sample solution under certain conditions. That is, the number of mg of oxygen in the oxidizing agent consumed for oxidizing the reduced matter in 1 liter of the sample solution is expressed in mg/L. COD measurement is the measurement of the concentration of organic matters and inorganic oxides in water so as to reflect the degree of pollution of water bodies by reducing substances, and is an important index for evaluating water quality. As the water body is most commonly polluted by organic matters, and COD is most direct to evaluate the organic matter pollution condition of the water body, the COD is also one of the most key physicochemical indexes in the water quality detection of environmental protection. Meanwhile, in all links of selection and design, research and application of sewage and wastewater treatment technologies, processes, methods and flows, COD index values are always used as scales to penetrate through the COD index values, and the COD index values are indispensable.
Traditionally, there are several methods for measuring COD:
the method belongs to a standard method of dichromate method 'HJ 828-2017 water quality chemical oxygen demand determination'. The method has the advantages of wide measurement range, good reproducibility, strong interference elimination, and high accuracy and precision. However, the test needs to be carried out under the conditions of strong acid, potassium dichromate, mercury sulfate, silver sulfate and heating, so that secondary environmental pollution is easily caused, the risk is high, the danger is high, the operation is complex, the measurement time is long, and the method is not suitable for outdoor rapid detection; in addition, the used medicament and reagent consumables are expensive and poor in economy.
The second is ultraviolet spectrophotometer method. The method has the advantages of no need of adding reagents, no secondary environmental pollution, simple and safe operation, short measurement time and suitability for outdoor rapid detection; but the defects are that the ultraviolet spectrum is only sensitive to aromatic organic matters and organic matters with double bonds in water, is not sensitive to organic matters with other structures, and has a limited range for measuring pollutants in water; the requirement on the turbidity of water is high, and the detection on relative complex dirt and waste water is not applicable.
And thirdly, an electrochemical oxidation method. The principle of the method comprises a hydroxyl-electrochemical oxidation method, an ozone oxidation method and the like, and the method still uses a strong oxidant to oxidize the reduced substances in the water, calculates the amount of the oxidant consumed when the strong oxidant oxidizes the reduced substances in the sample solution, and finally converts the COD value. The hydroxyl-electrochemical oxidation method is a method for applying an oxidant to a sample liquid and obtaining a redox current by utilizing the fact that some metal oxides have the function of catalytically generating and releasing hydroxyl radicals under certain conditions. The method has the characteristics of wide measurement range, no secondary pollution to the environment, safe and simple operation and short time, thereby becoming the most feasible method for replacing the dichromate method generally considered in the industry at present.
The COD measuring instrument using electrochemical oxidation method which is introduced in the market in recent years mainly comprises an electrode unit for providing oxidation-reduction current, a reaction cell unit and an electronic processing control unit for data acquisition, processing, storage, display and control. Wherein the electrode unit and the reaction tank unit are core structural members of the COD tester. The structure and performance of the device directly influence the structural performance of the whole COD tester, and relate to the repeatability, accuracy, long and short testing time, operation stability, environmental friendliness, working efficiency, operation cost and the like of the testing process.
The electrode unit of the COD measuring instrument comprises a working electrode, a counter electrode and a reference electrode, the reaction cell unit comprises a reaction cell and a cell cover frame, and the three electrodes are respectively inserted into the reaction cell filled with sample liquid to be measured and are fixed on the reaction cell through the cell cover frame. The working electrode is formed by plating PbO on a platinum plate2The plating layer is used for generating a strong oxidant, acting on a water body and obtaining an oxidation-reduction current; the counter electrode adopts a single pure platinum plate, and the counter electrode and the working electrode form an electric circuit; the reference electrode is a calomel electrode, and the reference electrode and the working electrode form a compensation circuit and provide fixed voltage, so that high-precision and accuracy tests are realized. In operation, a decreasing negative voltage is applied to the counter electrode by the electronic process control unit to a constant value, since PbO2The electrochemical counter electrode has catalytic performance, when the counter electrode voltage is lower than-1.4V, hydroxyl radicals with super-strong oxidizing performance are continuously generated on the surface of the working electrode, reducing substances in the sample liquid are rapidly decomposed, corresponding redox current is generated according to the concentration of the reducing substances, the redox current which correspondingly changes along with the change of the concentration of the reducing substances in the sample liquid is transmitted to the electronic processing control unit through the working electrode, and COD detection data are obtained after analysis and processing.
The defects brought by an electrode unit and a reaction tank unit of the prior COD tester are as follows:
the test method has the advantages that the repeatability of the test process is poor, the test accuracy is influenced, and the test speed is low;the electrodes need to be reconditioned and cleaned after each sample test. PdO is damaged in each repairing and cleaning process2The risk of facing results in test failure. Meanwhile, the regeneration process is complex in operation, the cleaning quality is difficult to ensure, and the change of the properties of the electrode can be caused by slight changes of the repair environment and operation, so that the test repeatability is difficult to ensure. Therefore, the popularization and the application of the electrochemical oxidation COD determinator are also limited. The working electrode is repeatedly used, so that the consistency of the performance is poor, the detection accuracy is influenced, and the operation time is prolonged; the operation is complicated, the time and the labor are consumed, and the current measuring period is more than 10 minutes. In addition, the electrode unit and the reaction tank unit are of split type, the structure is dispersed, the volume is large, and the volume of the reaction tank exceeds 100cm3And the liquid amount of the reaction tank is easy to change in operation, so that the test accuracy is influenced.
The material cost and the manufacturing cost are high, and the economical efficiency is poor; the working electrode is formed by adding PbO on the surface of the platinum plate through an electroplating process2The thickness uniformity and the density of the plating layer of the solid electrode of the plating layer are not well controlled, the manufacturing is difficult, the operation cost is high, the yield is low, and particularly, the working electrode and the counter electrode are both made of noble metal platinum, so the material cost is also increased.
The electrode unit and the reaction tank unit are of a split structure, the structure is dispersed, the size of the component is large, the electrode unit is provided with three electrodes including a working electrode, a counter electrode and a reference electrode, the length of each electrode is more than 10cm, and the volume of the reaction tank is more than 100cm3Therefore, the volume is large, and the COD measuring instrument adopting the electrode unit is limited to be applied to a laboratory.
From the application environment of the current COD tester, along with the rapid development of water environment protection and treatment work, the water pollution prevention enters a new stage, and especially for emergency situations, higher requirements are provided for the detection of the COD tester. The emergency condition mainly refers to 'sudden inspection' performed by a supervision department at any time in water pollution emergency and supervision and inspection, and the requirement is mainly embodied in that the detection is fast, accurate and safe. Therefore, for the research and development of the portable COD rapid determinator of cooperation, how to improve on the basis of current electrode unit and reaction cell unit structure to simplify the structure, provide a repeatability good, quick, accurate, the structure is succinct, convenient operation and cost reduction's small-size integrated configuration becomes the problem of industry's concern.
SUMMERY OF THE UTILITY MODEL
The utility model mainly aims to solve the problems and provides a disposable integrated electrode unit for a portable rapid COD (chemical oxygen demand) tester, which has the advantages of simplified structure, small size, compactness and high electrode consistency, thereby achieving the effects of good operation repeatability, rapid and accurate test and cost reduction suitable for outdoor emergency application.
The technical scheme adopted by the utility model for solving the technical problems is as follows:
a disposable integrated electrode unit for a portable COD rapid determinator is characterized by comprising a working electrode, a counter electrode, a reaction tank and a tank sleeve, wherein the working electrode is formed by adding screen printing PbO to the end of a copper foil surface of a single-sided PCB copper-clad substrate connected with the reaction tank2The counter electrode is a rectangular plate body formed by adding a silk-screen printing Ag coating on the end of a copper foil surface connecting reaction tank of a single-sided PCB copper-clad substrate; the reaction tank is a square body, a cylindrical reaction cavity penetrating through the front and the back of the tank body is formed along the front and back horizontal center lines of the reaction tank, a tank liquid inlet duct communicated to the top surface of the square body is vertically formed in the middle of the reaction cavity, and a front dustpan-shaped groove and a rear dustpan-shaped groove with openings on the left sides are respectively formed in the front and back surfaces of the square body and matched with the working electrode and the counter electrode; the working electrode and the counter electrode are oppositely and respectively sealed and cover the front and rear ports of the reaction cavity and are embedded into the front dustpan-shaped groove and the rear dustpan-shaped groove; the tank sleeve is a square sleeve matched with the square body of the reaction tank, the reaction tank is tightly attached to the wall of the square sleeve and is embedded into the sleeve, the right end face of the square sleeve is provided with a circumferential blocking edge for positioning the reaction tank, and the top surface of the square sleeve is aligned with the tank liquid inlet pore passage to form a sleeve liquid inlet hole.
The single-sided PCB copper-clad substrate adopts an anti-corrosion single-sided gold-immersion PCB copper-clad substrate or a single-sided tin-plating PCB copper-clad substrate.
PbO of the working electrode2Coating and counter electrodeThe Ag coating layer respectively accounts for 50-60% of the plate surface of each electrode plate body, and bevel lead angles are arranged at the electrode interface ends of the working electrode and the counter electrode, which are connected with the measuring instrument.
And the four corners of the inner wall of the square sleeve of the pool sleeve are respectively provided with an inwards concave opening through groove with a circular cross section along the axial direction.
The end of the pool liquid inlet hole channel is a conical surface inner concave opening, and the sleeve liquid inlet hole is composed of a sleeve channel with the diameter larger than the outer diameter of the conical surface inner concave opening and a conical surface inner concave opening of the end of the sleeve channel.
The front dustpan-shaped groove and the rear dustpan-shaped groove of the reaction tank are formed by correspondingly and mutually connecting the front edge and the rear edge of the top surface of the reaction tank, the front edge and the rear edge of the right end surface of the reaction tank and the convex edges formed by outwards extending the front edge and the rear edge of the bottom surface of the reaction tank.
The reaction tank and the tank sleeve are both injection-molded integrated parts and are made of hard plastics.
And anti-skid grains are arranged on the outer sides of the front and the back of the pool sleeve.
The overall dimension of reaction tank is for being long 20 + -5 mm wide 6 + -1 mm high 15 + -3 mm by x, and the diameter of feed liquor chamber is 8 + -0.5 mm, the overall dimension of pond cover is for being long 21 + -5 mm wide 14 + -3 mm high 20 + -1 mm by x, the diameter in pond feed liquor pore is 0.6-0.8mm, the size of working electrode and counter electrode is for being long 26 + -5 mm wide 13 + -3 mm thick 1.6 + -0.5 mm by x.
And an injector which is matched with the integrated electrode unit and used for injecting the liquid to be detected into the reaction cavity is arranged.
The utility model has the beneficial effects that: compared with the prior art, the method has the advantages that,
the test process has high repeatability, and the test accuracy is improved;
the disposable integrated electrode unit provided by the utility model overcomes the defect of poor repeatability in the traditional technology, and firstly, the working electrode adopts uniform and compact screen printing PbO from the structural performance2The coating replaces the traditional PbO2The solid electrode has stable electrical property; the electrode unit and the reaction tank unit are combined into a whole, the reaction chamber of the reaction tank is combined with the working electrode and the embedded sealing of the counter electrode, and the reaction tank is tightly sleeved and fixed with the tank sleeve,the pollution is prevented, the area of the polar plate of the working electrode and the polar plate of the counter electrode which are contacted with the sample liquid is fixed, the distance between the parallel polar plates is fixed, the capacity of the reaction tank is fixed, the reaction tank is sealed and does not seep liquid, and the liquid quantity is ensured to be constant. The electrochemical oxidation COD measuring device has the advantages that the device is small in size, compact in insertion, and capable of combining with a precise small and light integrated electrode unit, and is more convenient for strictly controlling various technical indexes of a working electrode, a counter electrode, a reaction tank and a tank sleeve in the production, manufacturing and packaging processes, so that the repeatability in the electrochemical oxidation COD measuring process is ensured, the detection accuracy is improved, and the COD is technically measured by using an electrochemical method.
The testing speed is high
Firstly, the method is based on the principle of a hydroxyl-electrochemical oxidation method, and effectively shortens the reaction time by reducing the volume of a reaction tank and the distance between electrodes to the maximum extent; secondly, the disposable electrode is adopted, so that not only are the regeneration repair and cleaning operations omitted, but also the operation time is saved; compared with the existing structure with dispersion and large space, the testing time of the utility model is shortened to be less than 15 seconds from more than 10 minutes of the existing electrode, the effect of obtaining testing data within 15 seconds is realized, and the detection efficiency is improved.
The material cost and the manufacturing cost are reduced, and the economy is improved;
firstly, the working electrode is formed by adding screen printing PbO on a PCB gold immersion or tin plating copper-clad substrate2The coating, the counter electrode is to add the screen printing Ag coating on the PCB gold immersion or tinned copper-clad substrate, belongs to the traditional mature process technology, and has low operation cost. In addition, a working electrode and noble metal platinum applied to the counter electrode in the traditional process are omitted, and the material cost is obviously reduced. In addition, the PCB substrate can be recycled. In particular, the integrated electrode unit realizes miniaturization and material saving, the precise structure ensures that the distance between the working electrode of each integrated electrode and the parallel polar plate of the counter electrode is fixed, the area of the polar plate contacting with the sample liquid is fixed, and the tank capacity of the reaction tank is fixed, so that high-precision and accuracy tests can be realized without a compensation circuit of a reference electrode, and the reference electrode is omitted. Integrates the above factorsThe material cost and the manufacturing cost of the utility model are obviously reduced, and good economic performance is reflected.
The body is small and light, the structure is simplified, and outdoor detection requirements are met;
the integrated electrode unit reduces the volume of the reaction cell and the distance between the electrodes to the maximum extent, omits a reference electrode and realizes simple and small structure. The volume of the portable COD rapid detector is reduced to below 1/5 of the total volume of the prior electrode unit and the prior reaction cell unit, and the portable COD rapid detector completely meets the requirement of the portable COD rapid detector for outdoor use under the emergency condition.
Drawings
FIG. 1 is a schematic front view of the present invention;
FIG. 2 is a left side view of FIG. 1
FIG. 3 is a right side view of the working electrode of FIG. 2;
FIG. 4 is a left side view of the counter electrode of FIG. 2;
FIG. 5 is a right side cross-sectional view of the reaction cell of FIG. 2;
FIG. 6 is a structural view of the reaction cell in FIG. 2;
FIG. 7 is a right side cross-sectional view of the well cover of FIG. 2;
FIG. 8 is a structural view of the well casing of FIG. 2;
fig. 9 is a schematic view of the assembly and syringe insertion of the present invention.
In the figure: 1 working electrode, 11 gold-deposited layer, 12PbO2The device comprises a coating, 2 pairs of electrodes, 21 gold-depositing layers, 22Ag coatings, 3 reaction tanks, 31 tank liquid inlet channels, 32 conical surface inner notches, 33 reaction chambers, 34 front dustpan-shaped grooves, 35 rear dustpan-shaped grooves, 4 tank sleeves, 41 sets of channels, 42 conical surface inner notches, 43 ring peripheral retaining edges, 44 concave opening through grooves, 45 anti-skid grains and 5 injectors.
The utility model is described in detail below with reference to the figures and examples.
Detailed Description
Fig. 1 to 9 show the structural composition and the assembly process of a disposable integrated electrode unit for a portable rapid COD analyzer.
The integrated electrode unit provided by the utility model is characterized by comprising a working electrode 1 and a counter electrodeA pole 2, a reaction tank 3 and a tank sleeve 4, wherein the working electrode 1 is formed by adding screen printing PbO at the end of a copper foil surface of a single-sided PCB copper-clad substrate connected with the reaction tank2The counter electrode 2 is a rectangular plate body formed by adding a screen printing Ag coating at the end of a copper foil surface connecting reaction tank of a single-sided PCB copper-clad substrate.
In order to improve the oxidation resistance and the corrosion resistance of the single-sided PCB copper-clad laminate, the single-sided PCB copper-clad substrate adopts a commercially available anti-corrosion single-sided gold-immersion PCB copper-clad substrate or a single-sided tin-plated PCB copper-clad substrate. Namely, gold immersion or tinning oxidation and rust resistance treatment is carried out on the surface of the copper foil. This example employs a "gold immersion" process.
As shown in FIGS. 3-4, the working electrode 1 is formed by adding screen printing PbO to the end of the immersion gold layer connecting reaction tank of the single-sided PCB copper-clad substrate2And the counter electrode is a rectangular plate body formed by adding a screen printing Ag coating to the end of a gold immersion layer connecting reaction tank of the single-sided PCB copper-clad substrate 2. The utility model adopts the traditional mature silk-screen printing process, PbO2The printing paste and the Ag printing paste are respectively prepared by using superfine PbO with the granularity of more than 500 meshes2And Ag powder as main component and proper amount of adhesive and dispersant. Therefore, a compact and uniform conductive coating with consistent thickness is formed, and the high consistency of the electrode plate product is ensured.
In practical production, the working electrode 1 is PbO2The coating 12 and the Ag coating 22 of the counter electrode 2 respectively account for 50-60% of the plate surface of each electrode plate body. The electrode interface ends of the working electrode 1 and the counter electrode 2, which are connected with the measuring instrument, are provided with bevel lead angles, so that the working electrode and the counter electrode are conveniently and smoothly inserted into the electrode interface of the measuring instrument. In the fabrication, the structural dimensions of the working electrode 1 and the counter electrode 2 should take into account the matching of the dimensions of the interface with the electrodes of the meter.
The reaction tank 3 is a square body, as shown in fig. 5-6, a cylindrical reaction chamber 33 penetrating through the front and back of the tank body is arranged along the front-back horizontal center line, and a tank liquid inlet channel 31 communicated to the top surface of the square body is vertically arranged in the middle of the reaction chamber 33. The front and back surfaces of the square body of the reaction tank 3 are matched with the working electrode and the counter electrode and are respectively provided with a front dustpan shaped groove 34 and a back dustpan shaped groove 35 with openings on the left side; the working electrode 1 and the counter electrode 2 are oppositely covered on the polar surface, and the front and the rear ports of the reaction cavity are respectively embedded into the front dustpan-shaped groove 34 and the rear dustpan-shaped groove 35.
In actual manufacturing, the front dustpan shaped groove 34 and the rear dustpan shaped groove 35 of the reaction tank are respectively formed by connecting the front edge and the rear edge of the top surface of the reaction tank, the front edge and the rear edge of the right end surface of the reaction tank and the convex edges formed by extending the front edge and the rear edge of the bottom surface of the reaction tank to each other. The length, width and depth of the groove bodies of the front dustpan-shaped groove 34 and the rear dustpan-shaped groove 35 are respectively matched with the length, width and thickness of the counter electrode 2 and the working electrode 1.
The front dustpan-shaped groove 34 and the rear dustpan-shaped groove 35 can enable the polar surfaces of the working electrode 1 and the counter electrode 2 to be relatively embedded into the groove, and seal the round holes on the two end surfaces of the reaction chamber 33, so that the distance between the two parallel electrode plates is equal, the contact areas of the two electrodes and the sample liquid to be detected are equal, the liquid volume in the reaction chamber is fixed, and a closed space which is only impermeable to the outside of the unique channel of the pool liquid inlet channel 31 is formed. The design provides guarantee for repeatability and consistency of test data.
The tank sleeve 4 is a square sleeve matched with the square body of the reaction tank, the reaction tank 3 is tightly attached to the wall of the square sleeve 4 and is embedded into the tank, the right end face of the square sleeve 4 is provided with a circumferential retaining edge 43 for positioning the reaction tank 3, and the top face of the square sleeve is aligned with the tank liquid inlet hole channel 31 to form a sleeve liquid inlet hole.
In the utility model, in order to facilitate the insertion of the liquid injector and smoothly inject the measured sample liquid into the reaction cavity 33 during the test, the port of the liquid inlet duct 31 of the pool is a conical surface inner concave opening 32, and the sleeve liquid inlet hole is composed of a sleeve duct 41 with the diameter larger than the outer diameter of the conical surface inner concave opening 32 and a conical surface inner concave opening 42 at the port of the sleeve duct 41. Therefore, a closed and smooth flow guide channel is formed, and the tested sample liquid is ensured to be completely injected into the reaction cavity without spilling.
In the utility model, in order to ensure that the front, back, top and bottom four sides of the square body of the reaction tank 3 are tightly attached to the inner wall of the tank sleeve, the four corners of the inner wall of the square sleeve of the tank sleeve 4 are respectively provided with the concave open through grooves 44 with the circular cross section along the axial direction, so that the four sides of the inner wall form four integral raised wall bodies with gaps between the four sides of the inner wall to generate a certain elastic stress effect, and the plane of the inner wall can be tightly attached to the outer planes of the working electrode 1 and the counter electrode 2 to be stressed, laminated and tightly combined under the elastic clamping pressure, thereby ensuring the space of the reaction cavity 33 and the distance size precision between the working electrode 1 and the counter electrode 2 without generating liquid seepage. The structure is also an important guarantee measure for the repeatability and consistency of the integrated electrode unit. The reaction tank outer sleeve also has the functions of protecting and preventing pollution to the electrode system.
In the utility model, the reaction tank 3 and the tank sleeve 4 are both injection-molded integrated parts, and the adopted materials are hard plastics, such as ABS, PE and the like. Adopt integrative improvement structural integrity, realize succinctly small-size. In order to facilitate the operation and use of the operator, the outer sides of the front and the back of the pool cover are provided with anti-skid grains 45.
The integrated electrode unit provided by the utility model has the advantages that the reaction time is shortened, the volume of the reaction tank and the distance between electrodes are reduced to the maximum extent, and the compact and small structure is realized. The size is as follows:
the overall dimension of the reaction tank is 20 +/-5 mm in length, 6 +/-1 mm in width and 15 +/-3 mm in height, the diameter of the liquid inlet cavity is 8 +/-0.5 mm, the overall dimension of the tank sleeve is 21 +/-5 mm in length, 14 +/-3 mm in width and 20 +/-1 mm in height, the diameter of the liquid inlet channel of the tank is 0.6-0.8mm, and the dimensions of the working electrode and the counter electrode are 26 +/-5 mm in length, 13 +/-3 mm in width and 1.6 +/-0.5 mm in thickness.
In this embodiment, the overall dimensions of the reaction cell are 20mm long × 6mm wide × 15mm high, the diameter of the liquid inlet cavity is 8mm, the overall dimensions of the cell sleeve are 21mm long × 14mm wide × 20mm high, the diameter of the liquid inlet channel of the cell is 0.6mm, and the dimensions of the working electrode and the counter electrode are 26mm long × 13mm wide × 1.6mm thick.
It can be seen that the utility model adopts the modular integrated structure of structural miniaturization, assembly plug-in and close combination to combine the existing electrode unit and reaction cell unit together, and the reaction cell and cell sleeve also adopt the injection molding integrated piece with simple structure to integrally form the integrated piece with compact structure and small appearance. Compared with the prior art, the volume of the integrated electrode unit provided by the utility model is reduced to below 1/5 of the total volume of the existing electrode unit and the reaction cell unit, and the demand of an outdoor portable COD rapid determinator under emergency conditions is completely met.
Matching with the integrated electrode unit, the utility model is also provided with a liquid injector 5 for injecting the liquid to be detected into the reaction cavity 33. The injector 5 adopts a 1.0mL disposable syringe. In this example, the diameter of the cylindrical reaction chamber 33 is 8mm, the length of the cylindrical reaction chamber is 6mm, and the volume of the reaction chamber 33 is 3.14X 42×6mm3The syringe 5 can accurately control the injection amount by the syringe scale when the injection amount is 0.3mL, and the syringe is filled with more than 0.3 mL. During operation, the liquid is injected until the liquid is overflowed from the liquid inlet hole. If the plug in the syringe is pushed and pulled smoothly, the syringe can be cleaned by distilled water and sample liquid to be tested and then reused.
Operation and principle
The utility model is designed and manufactured based on a hydroxyl-electrochemical oxidation method. When in measurement, firstly, the working electrode 1 and the counter electrode 2 of the integrated electrode unit are inserted into an electrode interface of a COD (chemical oxygen demand) measuring instrument to be electrically connected with an electronic processing control unit of the instrument. Then, the sample liquid to be measured is filled into the reaction tank 3 through the liquid inlet hole and the liquid inlet duct of the tank by the liquid injector 5, and at this time, the working electrode 1 and the counter electrode 2 which are sealed at the front and rear ports of the reaction chamber 33 are conducted through the connection of the sample liquid. The negative voltage gradually decreased is applied to the counter electrode by the electronic processing control unit to be constant because of PbO2The electrochemical counter electrode has a catalytic performance, when the counter electrode voltage is lower than-1.4V, hydroxyl radicals with super-strong oxidizing performance are continuously generated on the surface of the working electrode, reducing substances in the sample liquid are rapidly decomposed, corresponding redox current is generated according to the concentration of the reducing substances, the redox current which correspondingly changes along with the change of the concentration of the reducing substances in the sample liquid is transmitted to the electronic processing control unit through the working electrode 1, and COD detection data are obtained after analysis and processing.
Application effects
Application practices prove that compared with data of a standard method, the integrated electrode unit provided by the utility model has the advantages of good repeatability, high consistency and high accuracy of test data, and meets the requirements of rapid, accurate, safe and effective field emergency detection of COD.
Example 1
And (3) testing the relevance of the integrated electrode unit: according to the dichromate method and the integrated electrode unit hydroxyl-electrochemical oxidation method, potassium hydrogen phthalate solutions with COD concentrations of 0.0mg/L, 10.0mg/L, 30.0mg/L, 100.0mg/L, 300.0mg/L and 500mg/L are respectively measured. The dichromate method is operated according to the relevant requirements of the standard HJ828-2017 water quality chemical oxygen demand determination dichromate method, which is not repeated. The integrated electrode unit test operation steps are as follows: and (3) inserting the integrated electrode unit into an electrode interface of an instrument, sucking 0.5mL of potassium hydrogen phthalate solution with COD concentration of 0.0mg/L by using an injector, then inserting the integrated electrode unit along the sleeve liquid inlet hole, injecting liquid until the liquid overflows visibly, and then starting to measure and obtain measurement data. The COD concentrations of the potassium hydrogen phthalate solutions of 10.0mg/L, 30.0mg/L, 100.0mg/L, 300.0mg/L and 500mg/L were measured successively according to the above-mentioned procedures. The measurement data for both methods are shown in table 1:
TABLE 1 correlation measurement data
As can be seen from the data in Table 1, the degree of fitting and the correlation of the hydroxyl-electrochemical oxidation method of the integrated electrode unit are very good and completely reach the determination level of the standard test method by the dichromate method.
Example 2
Testing the consistency of the integrated electrode unit: firstly, the integrated electrode unit is inserted into an electrode interface of an instrument, 0.5mL of potassium hydrogen phthalate solution with COD concentration of 20.0mg/L is absorbed by an injector, and then the integrated electrode unit is inserted along a sleeve liquid inlet hole and injected until the integrated electrode unit overflows when being seen; then, measurement is started and measurement data is obtained. This operation was repeated 6 times with 6 integrated electrode units, respectively; the potassium hydrogen phthalate solution with COD concentration of 200.0mg/L and 500.0mg/L is continuously measured according to the operation method, and three groups of measurement data are shown in the following table:
TABLE 2 consistency measurement data
The measurement method can be considered to have better consistency if the relative error of the measured data is between-5.0% and 5.0%. As can be seen from the data in Table 2, the integrated electrode unit has the advantages of good consistency, small fluctuation of measured data and high repeatability, and ensures the authenticity and reliability of each measurement result.
Example 3
Testing the applicability of the integrated electrode unit: according to a dichromate method and an integrated electrode unit hydroxyl-electrochemical oxidation method, surface water, domestic sewage and sewage treatment plant discharge water are respectively measured. The dichromate method is operated according to the relevant requirements of the standard HJ828-2017 water quality chemical oxygen demand determination dichromate method, which is not repeated. The integrated electrode unit test operation steps are as follows: after the measuring instrument enters a sample measuring mode, the integrated electrode unit is inserted into an electrode interface of the instrument, 0.5mL of water sample to be measured is absorbed by an injector, the water sample is inserted along the sleeve liquid inlet hole and injected until the water sample overflows visibly, and then measurement is started to obtain measuring data. And sequentially measuring three water samples of surface water, domestic sewage and sewage discharged by a sewage treatment plant according to the operation sequence. The measurement data for both methods are shown in the following table:
TABLE 3 measurement data of suitability
As can be seen from the data in Table 3, the data obtained by the hydroxyl-electrochemical oxidation method of the integrated electrode unit is substantially the same as that obtained by the standard dichromate method. The integrated electrode unit hydroxyl-electrochemical oxidation method is high in accuracy and completely suitable for COD detection of an environmental water sample.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the structure and shape of the present invention in any way, and any simple modification, equivalent change and modification made to the above embodiment according to the technical spirit of the present invention are within the scope of the technical solution of the present invention.
Claims (10)
1. A disposable integrated electrode unit for a portable COD rapid determinator is characterized by comprising a working electrode, a counter electrode, a reaction tank and a tank sleeve, wherein the working electrode is formed by adding screen printing PbO to the end of a copper foil surface of a single-sided PCB copper-clad substrate connected with the reaction tank2The counter electrode is a rectangular plate body formed by adding a silk-screen printing Ag coating on the end of a copper foil surface connecting reaction tank of a single-sided PCB copper-clad substrate; the reaction tank is a square body, a cylindrical reaction cavity penetrating through the front and the back of the tank body is formed along the front and back horizontal center lines of the reaction tank, a tank liquid inlet duct communicated to the top surface of the square body is vertically formed in the middle of the reaction cavity, and a front dustpan-shaped groove and a rear dustpan-shaped groove with openings on the left sides are respectively formed in the front and back surfaces of the square body and matched with the working electrode and the counter electrode; the working electrode and the counter electrode are oppositely and respectively sealed and cover the front and rear ports of the reaction cavity and are embedded into the front dustpan-shaped groove and the rear dustpan-shaped groove; the tank sleeve is a square sleeve matched with the square body of the reaction tank, the reaction tank is tightly attached to the wall of the square sleeve and is embedded into the sleeve, the right end face of the square sleeve is provided with a circumferential blocking edge for positioning the reaction tank, and the top surface of the square sleeve is aligned with the tank liquid inlet pore passage to form a sleeve liquid inlet hole.
2. The disposable integrated electrode unit for a portable rapid COD determinator of claim 1, wherein the single-sided PCB copper-clad substrate is a rust-resistant single-sided gold-immersion PCB copper-clad substrate or a single-sided tin-plated PCB copper-clad substrate.
3. The disposable integrated electrode unit for a portable rapid COD analyzer according to claim 1 or 2, wherein the PbO of the working electrode is selected from the group consisting of2The Ag coating of the coating and the counter electrode respectively accounts for 50-60% of the plate surface of each electrode plate body, and the working electrode and the counter electrode are connectedThe electrode interface end of the setting instrument is provided with a bevel lead angle.
4. The disposable integrated electrode unit for a portable rapid COD meter according to claim 1 or 2, wherein the four corners of the inner wall of the square sleeve of the cell sleeve are respectively provided with an internally concave open through groove with a circular cross section along the axial direction.
5. The disposable integrated electrode unit for a portable rapid COD meter according to claim 1 or 2, wherein the port of the liquid inlet hole of the cell is a conical inner concave opening, and the sleeve liquid inlet hole is composed of a sleeve hole with a diameter larger than the outer diameter of the conical inner concave opening and a conical inner concave opening of the port of the sleeve hole.
6. The disposable integrated electrode unit for a portable rapid COD meter according to claim 1 or 2, wherein the front dustpan shaped groove and the rear dustpan shaped groove of the reaction cell are respectively formed by connecting the front and rear edges of the top surface of the reaction cell, the front and rear edges of the right end surface of the reaction cell and the front and rear edges of the bottom surface of the reaction cell extending outward.
7. The disposable integrated electrode unit for a portable rapid COD meter according to claim 1 or 2, wherein the reaction cell and the cell sleeve are both injection-molded integrated parts and made of hard plastics.
8. The disposable integrated electrode unit for a portable rapid COD meter according to claim 1 or 2, wherein the front and back outer sides of the battery cover are provided with anti-slip lines.
9. The disposable integrated electrode unit for a portable rapid COD analyzer according to claim 1 or 2, wherein the reaction cell has a dimension of 20 ± 5mm in length, 6 ± 1mm in width, 15 ± 3mm in height, the liquid inlet chamber has a diameter of 8 ± 0.5mm, the cell housing has a dimension of 21 ± 5mm in length, 14 ± 3mm in width, 20 ± 1mm in height, the cell liquid inlet channel has a diameter of 0.6 to 0.8mm, and the working electrode and the counter electrode have a dimension of 26 ± 5mm in length, 13 ± 3mm in width, and 1.6 ± 0.5mm in thickness.
10. The disposable integrated electrode unit for a portable rapid COD analyzer according to claim 1 or 2, wherein an injector for injecting a solution to be measured into the reaction chamber is provided in cooperation with the integrated electrode unit.
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| CN202121201689.6U CN215415178U (en) | 2021-05-31 | 2021-05-31 | Portable COD rapid determination appearance is with disposable integrated electrode unit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113358721A (en) * | 2021-05-31 | 2021-09-07 | 清池水环境治理科技发展(天津)有限公司 | Portable COD rapid determination appearance is with disposable integrated electrode unit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113358721A (en) * | 2021-05-31 | 2021-09-07 | 清池水环境治理科技发展(天津)有限公司 | Portable COD rapid determination appearance is with disposable integrated electrode unit |
| CN113358721B (en) * | 2021-05-31 | 2024-05-07 | 清池水环境治理科技发展(天津)有限公司 | Disposable integrated electrode unit for portable COD rapid determination instrument |
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