Online monitoring device for concentration of oxidizing agent in galvanic disinfectant of primary battery

Abstract

The utility model belongs to the technical field of electrochemistry, and relates to an on-line monitoring device for the concentration of an oxidizing agent in galvanic disinfectant of a primary battery. Comprising a sampling tube, two ends of the sampling tube are respectively provided with a sampling tube inlet and a sampling tube outlet, a primary battery positive electrode and a primary battery negative electrode are arranged in the sampling tube, and the primary battery positive electrode and the primary battery negative electrode pass through an insulating binding post on the tube wall of the sampling tube through a lead to form a loop with a micro galvanometer and a load resistor, and also comprises a timing switch, the micro-galvanometer is connected in parallel with two ends of the load resistor, and the potentiometer is connected in parallel with two ends of the load resistor. The timing switch in the device can preset'short circuit 'and'open circuit' periods, so that the oxidant concentration can be periodically and dynamically displayed. Compared with the existing concentration display method of oxidation-reduction potential (ORP), the concentration display device has the advantages that the response time is fast (lt); and the method can be widely applied to the medical treatment and public health industry, the food industry and the environmental protection industry.

Description

TECHNICAL FIELD

[0001] The utility model belongs to electrochemistry technical field, especially relate to a primary cell current type oxidant concentration on -line monitoring device. BACKGROUND

[0002] Chlorine-containing disinfectant and ozone water as disinfectant have been applied to water disinfection, medical and health, food processing industry, sewage treatment and other industrial fields. In the above disinfection application fields, it is necessary to monitor and control the concentration on-line to ensure the disinfection effect. Before the utility model, there are different on-line or off-line detection methods. For example: spectrographic method, mass spectrometry, colorimetric method, test paper and other methods, such as: Chinese patent: CN201520734716; CN201921715362; CN201510367332. The above detection methods have complex instrument circuit, high cost, and need professional technical personnel to debug to run normally, and DPD colorimetric method also needs to supplement DPD colorimetric reagent and other consumables regularly.

[0003] Except for DPD colorimetric method, all the above detection methods measure the display of the oxidation-reduction potential (ORP) of chlorine-containing disinfectant in water as the basic working principle, and the ORP potential value exists display "hysteresis". Due to the characteristic adsorption phenomenon on the electrode surface, when the concentration changes, the adsorption state of the active substance on the working electrode surface cannot be updated in time. The response time is long, and the real concentration of chlorine-containing preparation in water cannot be displayed accurately and timely. CONTENT OF THE UTILITY MODEL

[0004] In order to overcome the above technical defects, the utility model provides a kind of primary cell current type on-line monitoring oxidant (such as effective chlorine or ozone) concentration in disinfectant device and method.

[0005] According to Nernst formula:

[0006]

[0007] In formula (1): Equilibrium electrode potential, Standard electrode potential

[0008] a ox Oxidation state substance activity, a re Reduced state substance activity

[0009] n-Reaction electron gain and loss number, F-Faraday constant

[0010] When a ox =a re =1, It is called standard electrode potential.

[0011] If decimal logarithms are used, the above Nernst formula can be written as:

[0012]

[0013] From equation (2), it can be seen that the activity (a) of a certain oxidized substance is... ox ) and the equilibrium electrode potential of the galvanic cell It exhibits a semi-logarithmic relationship.

[0014] This invention employs a galvanic cell current-type device to detect oxidants in disinfectant solutions. The working principle is illustrated using available chlorine as an example:

[0015] Electrochemical reaction at the positive electrode (which also serves as the working electrode):

[0016] Electrochemical reaction at the negative electrode (also serving as a reference electrode):

[0017] Liquid phase reaction:

[0018] This invention employs a galvanic cell current-type device to detect oxidants in disinfectant solutions. Taking ozone as an example, the working principle is explained below:

[0019] Electrochemical reaction at the positive electrode (which also serves as the working electrode):

[0020] Electrochemical reaction at the negative electrode (also serving as a reference electrode):

[0021] When a galvanic cell is working, the oxidized material gains electrons and is reduced at the positive electrode (which also serves as the working electrode). This reduction current (i) flows through the load resistor (R) and produces a drop (iR). According to Ohm's law (V = iR), the voltage (V) across the load resistor (R) is linearly related to the reduction current (i).

[0022] At this point, the reduction current (i) and the oxidation state activity (a) ox The voltage (V) across the load resistor (R) is directly proportional to the activity (a) of the oxidized substance. ox They are directly proportional, which conforms to the Nernst formula.

[0023] As can be seen from the above working principle, the potential (V) across the load resistor (R) is the equilibrium potential of the positive terminal during operation. Value, this The value can be converted into the activity of the oxidized state (concentration x activity coefficient) using the Nernst formula.

[0024] The utility model discloses primary cell current type disinfectant concentration on -line monitoring device, including sampling pipe, the sampling pipe both ends have sampling pipe import and sampling pipe export respectively, the sampling pipe inside has primary cell positive pole and primary cell negative pole, primary cell positive pole and primary cell negative pole, through the lead wire to pass through the insulating binding post on the sampling pipe wall, with microcurrent meter and load resistance form loop, still include timing switch, and the both ends of microcurrent meter and load resistance form parallel, still include potentiometer, and the both ends of load resistance form parallel.

[0025] The monitoring device is provided with a load resistance (R) in the external circuit of the primary cell (see attached Figure 1 ) to obtain a reduction current (i) signal, and the voltage across the load resistance (R) is displayed. The concentration of the corresponding oxidized substance is calibrated in advance by the national standard iodine method. The calibration curve between the voltage and the oxidant concentration can be established. As long as the type of oxidant, the primary cell positive pole, the primary cell negative pole, and the load resistance are fixed, the calibration curve between the voltage and the oxidant concentration is fixed.

[0026] The monitoring device of the utility model can realize online detection and monitoring of the concentration of oxidized substances in disinfectant before leaving the factory by predefining the calibration curve. In the utility model, the timing switch is arranged between the positive pole and the negative pole in the external circuit of the primary cell. When the timing switch is "open", the voltage (V) across the load resistance (R) is displayed as When the timing switch is "closed", the voltage (V) across the load resistance (R) is displayed as , i.e. the potential value is "zeroed". When the potential value is "zeroed", the concentration of the adsorbed active substance on the positive pole surface tends to be zero, the original double-layer structure of the adsorbed substance on the positive pole surface is quickly dissociated, and the adsorption state on the positive pole surface is updated in real time.

[0027] After the timing switch is adopted, the potential value detected by the potentiometer is dynamically displayed according to the pre-set on / off period. The "lag" problem of the conventional detection (ORP) is overcome, and the "response time" is greatly shortened.

[0028] In the monitoring device, the effective chlorine or ozone water disinfectant measured is reduced by gaining electrons on the positive pole, and the reduction current (i) is proportional to the concentration of the disinfectant.The main body of the galvanic cell of this utility model device consists of a positive electrode (which also serves as the working electrode), a negative electrode (which also serves as the counter electrode and reference electrode), and an electrolyte in the aqueous solution to be tested.

[0029] The positive electrode (also serving as the working electrode) of the galvanic cell described in this invention is composed of platinum, gold, or noble metal oxides (RuO2 / Ti, IrO2 / Ti, TaO2 / Ti) or mixed noble metal oxides.

[0030] The negative electrode (which also serves as the reference electrode) of the galvanic cell described in this invention is composed of AgCl / Ag or HgCl / Hg.

[0031] The positive and negative electrodes of the galvanic cell described in this invention are respectively connected to the sample inlet tube via insulated terminals and are in contact with the aqueous solution being tested. The positive electrode of the galvanic cell is a long filament, and the negative electrode is a spring coil arranged around the anode filament. The active surface area of ​​the negative electrode is much larger than that of the positive electrode.

[0032] The timer switch described in this utility model can be controlled to operate in "open" and "closed" states according to a preset working cycle.

[0033] The micro-ammeter described in this utility model displays the current value (i) of the external circuit loop when the galvanic cell is working, which is the current value of the oxidized active material being reduced by electrons at the positive electrode.

[0034] The load resistor (R) described in this invention, during the discharge operation of the galvanic cell, has a reduction current (i) flowing through its positive electrode via a micro-ammeter. The potential value (iR value) is then dynamically displayed in real-time by a potentiometer. It can be determined by iodometric titration and converted into the concentration of effective chlorine oxidant.

[0035] The method for online monitoring of oxidants in disinfectant using the device of this invention includes the following steps:

[0036] Step 1: Determine the device at different temperatures using iodometric titration. The concentration of the oxidant is determined accordingly. Calibration curves with oxidant concentration;

[0037] Step 2: Preset the short-circuit time and open-circuit time of the timer switch, connect the sampling tube inlet of this device to the sampling port of the disinfection system, and let the disinfectant flow through the sampling tube and out from the sampling tube outlet.

[0038] Step 3: Start the timer switch and read the voltage across the load resistor during the open-circuit time. Based on the calibration curve established in step one, obtain the oxidant concentration at this point;

[0039] Step four, with the timing switch periodically short-circuit and open-circuit, thereby achieving the online dynamic monitoring of the oxidant concentration in the disinfectant.

[0040] As a preferred, in step one, the oxidant is ozone or available chlorine.

[0041] As a preferred, in step two, the short-circuit time is set to 10-20 seconds, and the open-circuit time is set to 2-5 minutes.

[0042] As a preferred, in step three, in the open-circuit time, when the reading of the micro-current meter changes less than 1% within 10 seconds, the product of the reduction current (i) and the load resistance (R) is the voltage

[0043] The primary battery current type oxidant online monitoring device has short response time (<10 seconds), no "hysteresis" in concentration display, low cost and compact structure, and can be widely applied to medical health, food industry, environmental protection industry and scientific research fields. The online dynamic detection method overcomes the "hysteresis" of the existing oxidation-reduction potential (ORP) method, greatly shortens the response time and improves the detection precision. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The primary battery type water oxidant concentration detection device structure schematic view, in the drawing 1-sampling pipe import; 2-sampling pipe; 3-primary battery positive electrode; 4-primary battery body; 5-primary battery negative electrode; 6-sampling pipe export; 7-timing switch; 8-micro-current meter; 9-potentiometer; 10-load resistance; 11-insulating terminal post.

[0045] Figure 2 The primary battery body structure schematic view;

[0046] Figure 3 The timing switch time interval and response potential (V) dynamic display diagram;

[0047] Figure 4 The available chlorine concentration (mg / L) and load resistance (iR) pressure drop relationship calibration curve diagram;

[0048] Figure 5 The water ozone concentration (mg / L) and load resistance (iR) pressure drop relationship calibration curve diagram. DETAILED DESCRIPTION

[0049] The method and device of the utility model will be further described below in combination with embodiments and drawings.

[0050] The utility model discloses a primary cell current type disinfectant solution oxidant concentration on -line monitoring device, including sampling pipe 2, sampling pipe 2 both ends have sampling pipe import 1 and sampling pipe export 6 respectively, the inside of sampling pipe 2 has primary cell positive pole 3 and primary cell negative pole 5, primary cell positive pole and primary cell negative pole, through the lead wire to pass through the insulating binding post 11 on the sampling pipe wall, with microcurrent meter 8 and load resistance 10 form loop, still include timing switch 7, with the both ends of microcurrent meter 8 and load resistance 10 form parallel, still include potentiometer 9, with the both ends of load resistance 10 form parallel.

[0051] The utility model discloses a primary cell body 4 core component of special design, according to the current of oxidant active substance in water reduction on primary cell positive pole 3, through load resistance 10 generates corresponding potential Value, the concentration of effective chlorine in water or the concentration of ozone water in water is instantaneously on -line dynamic display.

[0052] The primary cell positive pole 3 and the primary cell negative pole 5 of the primary cell body 4 are arranged in the sampling pipe 1, and the primary cell positive pole 3 and the primary cell negative pole 5 are exposed in the measured aqueous solution, so that the disinfectant to be detected can continuously update and flow through the two electrodes of the primary cell. The insulating binding post 11 is arranged on the wall of the sampling pipe 1 by using an insulating material.

[0053] The lead-out wires of the primary cell positive pole / negative pole are connected with the special electronic circuit. Referring to the attached Figure 1 .

[0054] The microcurrent meter 8 and the load resistance 10 are connected in series between the upper parts of the primary cell positive pole and the primary cell negative pole, to form an external loop of the electronic cycle. The potentiometer 9 is connected in parallel at the two ends of the load resistance 10, to dynamically display the iR value.

[0055] The timing switch 7 is connected in parallel at the two ends of the lead-out wires of the primary cell external positive / negative pole. The timing switch 7 can be pre-set to have a time period of "short circuit" (closed state) and "open circuit" (open state), and the dynamic display (iR) V and switch time relationship curve schematic diagram is shown in the attached Figure 3 .

[0056] When the timing switch 7 is closed, the primary cell outputs the limit current, at this time, the oxidant active substance is reduced and exhausted on the positive pole surface, that is, the "zero" state; when the timing switch is opened, at this time, the current of the oxidant active substance reduced on the positive pole flows through the load resistance (R) 10, according to Ohm's law, the load resistance (R) 10 periodically dynamically displays iR drop (V) at the two ends, and the iR (V) value is proportional to the reduction current. Through the national standard "iodine quantity method" analysis calibration, the concentration of the oxidant substance can be converted, and the attached Figure 4 、 5The calibration curve is shown below. Then, during testing, the concentration of the oxidant in the disinfectant is obtained by comparing the measured iR with the pre-prepared calibration curve.

[0057] The method for online monitoring of oxidants in disinfectant using the device of this invention includes the following steps:

[0058] Step 1: Determine the device at different temperatures using iodometric titration. The concentration of the oxidant is determined accordingly. Calibration curves with oxidant concentration;

[0059] Step 2: Preset the short-circuit time and open-circuit time of the timer switch, connect the sampling tube inlet of this device to the sampling port of the disinfection system, and let the disinfectant flow through the sampling tube and out from the sampling tube outlet.

[0060] Step 3: Start the timer switch and read the voltage across the load resistor during the open-circuit time. Based on the calibration curve established in step one, obtain the oxidant concentration at this point;

[0061] Step four: Through the periodic short-circuiting and open-circuiting of the timer switch, online dynamic monitoring of the oxidant concentration in the disinfectant solution is achieved.

[0062] As a preferred option, in step one, the oxidant is ozone or available chlorine.

[0063] Appendix Figure 4 The calibration curve is for a load resistance of 2MΩ, a positive electrode of Au and a negative electrode of AgCl / Ag, with available chlorine as the oxidant.

[0064] Appendix Figure 5 The calibration curve is for a load resistance of 220KΩ, a galvanic cell negative electrode of AgCl / Ag, and ozone as the oxidant.

[0065] The present invention provides an online dynamic detection method for galvanic cell current, which overcomes the shortcomings of the existing oxidation-reduction potential (ORP) method in displaying "lag" and significantly shortens the response time and measurement accuracy.

[0066] This invention relates to a galvanic cell current-based online oxidant monitoring device with a short response time (<10 seconds) and no lag in concentration display. It is low-cost and compact in structure. It can be widely used in medical and health, food industry, environmental protection, and scientific research fields.

Claims

1. An on-line monitoring device for the concentration of oxidizing agent in a galvanic current type disinfectant solution, characterized by, The application relates to a micro-current sampling device, which comprises a sampling tube with a sampling tube inlet and a sampling tube outlet at two ends respectively, a primary cell positive pole and a primary cell negative pole in the sampling tube, and a timing switch, a micro-current meter and a load resistor.

2. The device for on-line monitoring of oxidant concentration in disinfectant solution according to claim 1, characterized in that, The primary cell positive pole is made of metal platinum, gold or noble metal oxide or noble metal mixed oxide. 3.The device for on-line monitoring concentration of oxidant in disinfectant solution according to claim 1, characterized in that, The primary cell negative pole is made of AgCl / Ag or HgCl / Hg.

4. The device for on-line monitoring of oxidant concentration in disinfectant solution according to claim 1, characterized in that, The primary cell positive pole is in the shape of a long strip, and the primary cell negative pole is in the shape of a spring ring and arranged around the primary cell positive pole.

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