CN102331447A - Method and equipment for measuring chemical oxygen demand by photocatalytic oxidation process - Google Patents
Method and equipment for measuring chemical oxygen demand by photocatalytic oxidation process Download PDFInfo
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Abstract
The invention relates to a method and equipment for measuring the chemical oxygen demand by a photocatalytic oxidation process and belongs to the technical field of a method and equipment for monitoring the water quality. The method and the equipment are used for carrying out pollution monitoring on the water quality. The invention adopts the technical scheme that blank solution and liquid to be measured are respectively rapidly measured by three electrodes through the photocatalytic oxidation process, and current data differences of the blank solution and the liquid to be measured and the concentration of organic matter in the range of 0 to 200mg/L have a linear relation, so that the real-time detection of the concentration of the organic matter in water is realized; the measuring equipment consists of a liquid injection device, a measuring device and a data processing device; the measuring device comprises an ultraviolet lamp and a measuring tank; a working electrode, a reference electrode and a counter electrode are arranged in the measuring tank; and a tank side wall between the measuring tank and the ultraviolet lamp is a light window. The method adopted in the invention accords with the international standards, the measurement is rapid and accurate, the method has no pollution, a small using amount of a reagent and low detection limit, and is suitable for on-line measurement of a low-concentration sample. The equipment disclosed by the invention has a simple and reasonable structure, reliably operates and has high application value.
Description
Technical field
The present invention relates to a kind of photoactivation oxidizing process and measure the monitoring method and the equipment of COD in the water body, belong to water quality monitoring method and equipment technical field.
Background technology
COD (COD) is one of important indicator of estimating water pollution.At present, the main method of COD on-line determination has potassium dichromate oxidation, permanganate index method and ultraviolet absorption method.Potassium dichromate method meets the GB requirement; Accurate, the favorable reproducibility of mensuration result; But with the method the online COD automatic monitor of test philosophy is wanted consume expensive in practical application silver sulfate and big mercuric sulfate, the chromium ion of toxicity, the secondary pollution that causes, and the heating digestion time is long; Process is loaded down with trivial details, and sensitivity is low.The permanganate index method also is a national standard method, but it is low to organic oxidation efficiency, is inappropriate for the water body of heavy contamination, the mensuration of only suitable potable water, source water and the day water.Be based on that unsaturated organic molecule UV Absorption principle under the 254nm measures, this method is simple in structure, need not reagent, and maintenance is little, and operating cost is low.But relatively poor with the standard method correlativity, the water sample adaptive faculty is poor, influenced greatly by the water sample suspension.
Summary of the invention
Technical matters to be solved by this invention provide a kind ofly meet the GB standard, testing process is simple, analysis speed is fast, free of contamination photoactivation oxidizing process is measured COD method and apparatus.
The technical scheme that solves the problems of the technologies described above is:
A kind of photoactivation oxidizing process is measured the method for COD, and it takes following steps to carry out:
1, in measuring cell, place working electrode, contrast electrode, to electrode, working electrode is TiO
2Nanometer film-ITO working electrode, contrast electrode are the Ag/AgCl contrast electrode, to electrode be platinum to electrode, TiO wherein
2There are the electric potential difference of about 1.25V in nanometer film-ITO working electrode and Ag/AgCl contrast electrode;
2, clean whole measuring buret road, diluting tank, measuring cell with blank solution (electrolytic solution), after cleaning finishes, open sampling pump and inject blank solution to measuring cell; Make blank solution be full of circulation passage; Open peristaltic pump, get into the measurement state, the acquisition electrode signal; After treating that electrode signal is stable, write down blank current data I
0
3, with the sample of testing liquid: the volume ratio of blank solution is injected diluting tank according to the ratio of 0.2:1-1:1, sends in the measuring cell after stirring;
4, the UV-irradiation measuring cell is opened in input testing liquid the time, and the testing liquid height of input rises to the contact contrast electrode gradually, to electrode, and testing liquid is full of measuring cell, record test electric signal I
S;
5, the current data and the blank solution current data of testing liquid are made poor
; Promptly get effective measurement data of this testing liquid sample; Both differences and organic concentration are linear in 0～200mg/L scope, realize detecting in real time organic concentration in the water thus.
Above-mentioned photoactivation oxidizing process is measured the method for COD, and the ultraviolet light of said irradiation measuring cell and working electrode through the real-time feedback circuit of light intensity, makes light intensity keep constant by the output power of ultraviolet source control circuit control ultraviolet source.
A kind of equipment of realizing above-mentioned photoactivation oxidizing process mensuration chemical oxygen demand metering method; It is made up of fluid infusion apparatus, measurement mechanism, data processing equipment; The liquid output terminal of fluid infusion apparatus is connected with the liquid input end of measurement mechanism; The signal output part of measurement mechanism is connected with data processing equipment, and measurement mechanism comprises uviol lamp, measuring cell, working electrode, contrast electrode is installed, to electrode in measuring cell; Uviol lamp is installed in the back side of measuring cell, and the pond sidewall between measuring cell and the uviol lamp is an optical window.
The above-mentioned photoactivation oxidizing process of above-mentioned realization is measured the equipment of chemical oxygen demand metering method; Said fluid infusion apparatus is made up of diluting tank, infusion pipeline; Blank solution and testing liquid are connected to the inlet of diluting tank respectively through infusion pipeline; Stirring motor and paddle wheel are installed in the diluting tank, pump and valve are installed on infusion pipeline.
The above-mentioned photoactivation oxidizing process of above-mentioned realization is measured the equipment of chemical oxygen demand metering method; Said data processing equipment is made up of PC and signal circuit; One end of signal circuit is respectively with working electrode, contrast electrode, be connected to the signal output part of electrode, and the other end of signal circuit is connected with the signal output part of PC.
The above-mentioned photoactivation oxidizing process of above-mentioned realization is measured the equipment of chemical oxygen demand metering method, and said uviol lamp is connected with ultraviolet source, and ultraviolet source is connected with the ultraviolet source control circuit.
The above-mentioned photoactivation oxidizing process of above-mentioned realization is measured the equipment of chemical oxygen demand metering method, and the pond sidewall optical window of said measuring cell is that the quartz material of absorbing ultraviolet light is not processed.
The above-mentioned photoactivation oxidizing process of above-mentioned realization is measured the equipment of chemical oxygen demand metering method, and said working electrode is TiO
2Nanometer film-ITO working electrode, contrast electrode are the Ag/AgCl contrast electrode, are that platinum is to electrode to electrode.
Beneficial effect of the present invention:
The present invention is based on electrochemical three electrode principles, adopt the photoelectrocatalysioxidization oxidization method to measure fast, concrete grammar is to be directly proportional with the content of organic concentration according to nanometer working electrode output current to be the next really chemical oxygen demand of deciding of beasurement base.The method that the present invention adopts does not consume toxic reagent, non-secondary pollution; Adopt Flow Analysis Technique, measurement quick and precisely, reagent dosage is few, detection limit is lower, is applicable to the sample on-line determination of low concentration.The device structure advantages of simple of realization the inventive method, reliable, the The data real-time Transmission, whole device is easy to be processed into the quick on-line monitoring appearance of water quality of miniaturization, realizes on-line monitoring, has very high using value.
Description of drawings
Fig. 1 is the structural representation that photoactivation oxidizing process of the present invention is measured COD equipment;
Fig. 2 is the measuring cell structural representation that photoactivation oxidizing process of the present invention is measured COD equipment.
Mark is following among the figure: blank solution 1, testing liquid 2, waste liquid 3, pump 4, pump 5, pump 6, pump 7, valve 8, valve 9, infusion pipeline 10, diluting tank 11, stirring motor 12, paddle wheel 13, measuring cell 14, working electrode 15, contrast electrode 16, to electrode 17, optical window 18, ultraviolet source 19, inlet 20, set bolt 21, liquid outlet 22, leakage fluid dram 23.
Embodiment
The present invention is based on electrochemical three electrode principles, adopt the photoelectrocatalysioxidization oxidization method to measure fast, concrete grammar is to be directly proportional with the content of organic concentration according to nanometer working electrode output current to be the next really chemical oxygen demand of deciding of beasurement base.Photoactivation oxidizing process of the present invention is measured the method for COD and is taked following steps:
1, open pump 5, in diluting tank 11, inject blank solution 1,20s-40s closes pump 5, opens pump 6 after the time, clean measuring cell 14;
2, open pump 4, valve 8, valve 9, inject blank solution 1 to diluting tank 11,30s-150s closes pump 4, valve 8, valve 9 after the time, open pump 6, makes blank solution 1 be full of measuring cell 14, record current signal I
0Measurement finishes and opens pump 7 discharge blank solutions 1;
3, open pump 4, valve 8, valve 9, in diluting tank 11, inject blank solution 1,50s-400s is after the time; Inject testing liquid 2, the 50s-400s time, open stirring motor 12 simultaneously; Open pump 6 after sample introduction finishes, close pump 4, valve 8, valve 9 simultaneously, open pump 6; Testing liquid 2 is full of measuring cell, record sample current signal I
S, testing liquid 2 sample current data and blank current data are poor
Promptly get effective measurement data of this sample;
4, open pump 5, in diluting tank, inject blank solution 1, close pump 5 after a period of time, open pump 6, clean measuring cell 14, accomplish a measuring period.
Show among the figure; When above-mentioned measurement, open the sample that stepper motor will contain organic testing liquid 2 during measurement: the volume ratio of blank solution 1 is injected diluting tank 11 according to the ratio of 0.2:1-1:1, and diluting tank 11 is the tapered container of approximate circle of glass material; Treat that the liquid interpolation finishes; Open stirring at low speed motor 12, make liquid agitation even, slowly deliver in the laminar flows formula measuring cell 14 through peristaltic pump 6 at the uniform velocity.This thin layer measuring cell 14 is to be processed by corrosion-resistant transparent material, and measuring cell 14 is erect and is fixed on the instrument flow process plate, and measuring cell 14 back sides are the uviol lamp of certain power fixedly.Part forms optical window 18 between measuring cell 14 and the uviol lamp, must select quartz material for use, guarantees not absorbing ultraviolet light.Under the irradiation catalysis of ultraviolet light, TiO
2Nanometer film-ITO working electrode 15 discharges strong oxide 0H base, organism in the quick oxidize water of ability, and the output power of ultraviolet source control circuit control ultraviolet source 19 through the real-time feedback circuit of light intensity, makes light intensity keep constant.Measuring cell 14 is the notch cuttype Seal Design; The flow of solution vias inner walls is smooth; Sample slowly pours in from the inlet 20 of measuring cell 14; Liquid height rises to contact contrast electrode 16 gradually, during to electrode 17, begins to test electric signal, and the sample of last testing liquid 2 flows out from the liquid outlet 22 in measuring cell 14 upper right corner.Working electrode slide glass in the measuring cell 14 should be chosen the thin slice with good mechanical strength and high surface smoothness; Use 2 to gather the two-sided steady job electrode of tetrafluoro drive screw slide glass; Guarantee that thin slice forms the test thin layer of 1mm～3mm apart from uviol lamp, can regulate the size of measuring thin layer through the thickness of changing the working electrode slide glass.Earlier clean whole measurement stream before each the measurement, comprise infusion pipeline 10, diluting tank 11, measuring cell 14, cleaning process such as foregoing step 1,2 with blank solution.
In the present invention, said working electrode 15 is TiO
2Nanometer film-ITO working electrode, contrast electrode 16 are Ag/AgCl contrast electrodes, to electrode 17 be platinum to electrode, TiO wherein
2There are the electric potential difference of about 1.25V in nanometer film-ITO working electrode and Ag/AgCl contrast electrode.Adopt three electrode photoelectron-catalysis film measuring cells, 14 structures, guaranteed the stability of voltage.
Measuring cell 14 of the present invention adopts the material of insulation and good corrosion resistance, and the pad in the measuring cell 14 should be chosen the thin slice with good mechanical strength and high surface smoothness, and measuring cell 14 should have high surface smoothness with the surface of contact of pad.
Data transmission of the present invention realizes the real-time Transmission of data through RS232/485 output.
Claims (8)
1. a photoactivation oxidizing process is measured the method for COD, and it is characterized in that: it takes following steps to carry out:
(1) in measuring cell [14], place working electrode [15], contrast electrode [16], to electrode [17], working electrode [15] is TiO
2Nanometer film-ITO working electrode, contrast electrode [16] is the Ag/AgCl contrast electrode, to electrode [17] be platinum to electrode, TiO wherein
2There are the electric potential difference of about 1.25V in nanometer film-ITO working electrode and Ag/AgCl contrast electrode;
(2) clean whole measuring buret road, diluting tank [11], measuring cell [14] with blank solution [1], after cleaning finishes, open sampling pump and inject blank solution [1] to measuring cell [14]; Make blank solution [1] be full of circulation passage; Open peristaltic pump, get into the measurement state, the acquisition electrode signal; After treating that electrode signal is stable, write down blank current data I
0
(3) with the sample of testing liquid [2]: the volume ratio of blank solution [1] is injected diluting tank [11] according to the ratio of 0.2:1-1:1, sends into after stirring in the measuring cell [14];
(4) the input testing liquid is opened UV-irradiation measuring cell [14] [2] time, and the testing liquid of input [2] rises to contact contrast electrode [16] highly gradually, to electrode [17], and testing liquid [2] is full of measuring cell [14], record test electric signal I
S,
(5) current data of testing liquid [2] and the current data of blank solution [1] are made poor
; Promptly get effective measurement data of this testing liquid [2] sample; Both differences and organic concentration are linear in 0～200mg/L scope, realize detecting in real time organic concentration in the water thus.
2. photoactivation oxidizing process according to claim 1 is measured the method for COD; It is characterized in that: the ultraviolet light of said irradiation measuring cell [14] and working electrode is by the output power of ultraviolet source control circuit control ultraviolet source [19]; Through the real-time feedback circuit of light intensity, make light intensity keep constant.
3. realize that above-mentioned photoactivation oxidizing process measures the equipment of chemical oxygen demand metering method for one kind; It is characterized in that: it is made up of fluid infusion apparatus, measurement mechanism, data processing equipment; The liquid output terminal of fluid infusion apparatus is connected with the liquid input end of measurement mechanism; The signal output part of measurement mechanism is connected with data processing equipment, and measurement mechanism comprises uviol lamp, measuring cell [14], working electrode [15], contrast electrode [16] is installed, to electrode [17] in measuring cell [1]; Uviol lamp is installed in the back side of measuring cell [14], and the pond sidewall between measuring cell [14] and the uviol lamp is optical window [18].
4. the above-mentioned photoactivation oxidizing process of realization according to claim 3 is measured the equipment of chemical oxygen demand metering method; It is characterized in that: said fluid infusion apparatus is made up of diluting tank [11], infusion pipeline [10]; Blank solution [1] and testing liquid [2] are connected to the inlet of diluting tank [11] respectively through infusion pipeline [10]; Stirring motor [12] and paddle wheel [13] are installed in the diluting tank [11], on infusion pipeline [10], pump and valve are installed.
5. the above-mentioned photoactivation oxidizing process of realization according to claim 4 is measured the equipment of chemical oxygen demand metering method; It is characterized in that: said data processing equipment is made up of PC and signal circuit; One end of signal circuit is respectively with working electrode [15], contrast electrode [16], be connected to the signal output part of electrode [17], and the other end of signal circuit is connected with the signal output part of PC.
6. the above-mentioned photoactivation oxidizing process of realization according to claim 5 is measured the equipment of chemical oxygen demand metering method, and it is characterized in that: said uviol lamp is connected with ultraviolet source [19], and ultraviolet source [19] is connected with the ultraviolet source control circuit.
7. the above-mentioned photoactivation oxidizing process of realization according to claim 6 is measured the equipment of chemical oxygen demand metering method, it is characterized in that: the pond sidewall optical window [18] of said measuring cell [14] is that the quartz material of absorbing ultraviolet light is not processed.
8. the above-mentioned photoactivation oxidizing process of realization according to claim 7 is measured the equipment of chemical oxygen demand metering method, and it is characterized in that: said working electrode [15] is TiO
2Nanometer film-ITO working electrode, contrast electrode [16] is the Ag/AgCl contrast electrode, is that platinum is to electrode to electrode [17].
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| CN201110106607A CN102331447A (en) | 2011-04-27 | 2011-04-27 | Method and equipment for measuring chemical oxygen demand by photocatalytic oxidation process |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102818778A (en) * | 2012-07-25 | 2012-12-12 | 漳州师范学院 | Method for rapid determination of chemical oxygen demand in environmental water sample |
| CN102866186A (en) * | 2012-09-12 | 2013-01-09 | 合肥工业大学 | Circulating-type water chemical oxygen demand detection photoelectrochemical sensor |
| CN103954671A (en) * | 2014-05-07 | 2014-07-30 | 北京化工大学 | Online chemical oxygen demand monitoring device |
| CN105510423A (en) * | 2015-12-29 | 2016-04-20 | 南京洁态环保科技有限公司 | Automatic on-line monitor for measuring water body COD (chemical oxygen demand) |
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| CN101563602A (en) * | 2006-12-22 | 2009-10-21 | 水体检测有限公司 | Improved water analysis |
| CN101563603A (en) * | 2006-12-22 | 2009-10-21 | 水体检测有限公司 | Improved online water analysis |
| US7759125B2 (en) * | 2003-04-04 | 2010-07-20 | Aqua Diagnostic Pty Ltd | Photoelectrochemical determination of chemical oxygen demand |
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| US7759125B2 (en) * | 2003-04-04 | 2010-07-20 | Aqua Diagnostic Pty Ltd | Photoelectrochemical determination of chemical oxygen demand |
| CN101563602A (en) * | 2006-12-22 | 2009-10-21 | 水体检测有限公司 | Improved water analysis |
| CN101563603A (en) * | 2006-12-22 | 2009-10-21 | 水体检测有限公司 | Improved online water analysis |
Non-Patent Citations (2)
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102818778A (en) * | 2012-07-25 | 2012-12-12 | 漳州师范学院 | Method for rapid determination of chemical oxygen demand in environmental water sample |
| CN102818778B (en) * | 2012-07-25 | 2015-08-12 | 闽南师范大学 | A kind of method of Fast Measurement Determination of Chemical Oxygen Demand in Aqueous samples |
| CN102866186A (en) * | 2012-09-12 | 2013-01-09 | 合肥工业大学 | Circulating-type water chemical oxygen demand detection photoelectrochemical sensor |
| CN103954671A (en) * | 2014-05-07 | 2014-07-30 | 北京化工大学 | Online chemical oxygen demand monitoring device |
| CN103954671B (en) * | 2014-05-07 | 2016-03-23 | 北京化工大学 | Chemical oxygen demand (COD) on-Line Monitor Device |
| CN105510423A (en) * | 2015-12-29 | 2016-04-20 | 南京洁态环保科技有限公司 | Automatic on-line monitor for measuring water body COD (chemical oxygen demand) |
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Application publication date: 20120125 |