CN1036638A - New style chemical oxygen consumption measuring instrument - Google Patents

Abstract

This instrument adopts the solid well heater, has invented and has not had the quick digestion process of backflow, and the measured result accuracy is good, the precision height.For sewage, get the 25ml water sample in 16 * 130mm reaction tube, add 0.6ml oxygenant A and 5.0ml catalysis complexing agent C, heating is 10 minutes in 165 ℃ of thermostats, adds 25ml current potential synergistic agent D then, carries out potential measurement, and display directly shows measured value.This result and potassium dichromate circumfluence method have good consistance.For the analysis of life water and service water, with KmnO ₄Method is basic identical, has just replaced original titration with potential measurement.

Description

New style chemical oxygen consumption measuring instrument

● the present invention belongs to the instrument manufacturing technology.

● background technology of the present invention.

COD assay method the earliest is Adeney and Dawson ⁽¹⁾Propose.The method that extensively adopts both at home and abroad is that so-called chemical standard method is based on Muers at present ⁽²⁾Work.Moore ⁽³⁾Deng the people this method is used sewage analaysis.This method is operated numerous rope, and analysis time is long.Often make production and research cause difficulty.Gu this, how domestic and international many scientists round shortening analysis time, and problem such as simplify the operation has been carried out widely and worked.

Leither ⁽⁴⁾Adopt segmentation method Deng the people, get the 20ml sample, add 10ml0.25NK respectively ₂G ₂O ₇Solution, 0.4gHg SO ₄With 40ml sulfuric acid, refluxed 10 minutes, cool off and add 100ml distilled water after 5 minutes, carry out residual titration then.JirKa ⁽⁵⁾Think that Deng the people it is a condition test that the standard circumfluence method of COD is measured, so data that express method is surveyed are difficult to consistent with standard law.For this reason, they still adopt 2 hours return time.

For water sample through postdigestive detection, Gaudy ^(6.7.8)Think and to adopt spectrophotometric method to replace titrimetry to react the analysis of back digestive juice Deng the people.In order to eliminate 2 hours formality of return digestion, Best ⁽⁹⁾Carried out the research of sealed tube method Deng the people.Soon, Casseres ⁽¹⁰⁾Carry out the test of open pipe formula Deng the people, more a little than the sealed tube safety of Best from the view of security, but because of same heating 2 hours, because water evaporation in the digestive juice, solution concentration changed greatly, causes bigger test error for this reason.

At home, the instrument that style chemical oxygen consumption measuring instrument that Tai County, Jiangsu electrochemical analytical instrument factory produces and Great Wall, Shanghai radio factory produce all adopts backflow in 15 minutes, carry out coulomb then and all adopt backflow in 15 minutes, carry out coulometric titration then with the instrument that Great Wall, Shanghai radio factory produces.(1) though, the return time of this instrument reduces to 15 minutes, other running time does not reduce, so the whole operation time is still longer.(2), owing to still prolong with the backflow program of standard law and increased the preceding sample preparation of reaction, the formality of numerous rope is growing on and on.(3), the used time of coulometric titration, change with the COD value of sample size.(4), for the water sample of different COD values, need to select different volume of water sample carry out the branch sample.(5), in order to eliminate CL in the water sample ^-The interference of ion will be handled before the water sample sampling.

Purpose of the present invention

1, in order to eliminate traditional backflow program, make operating performance simplify, reduce accidental error simultaneously.

2,, make the needs that satisfy wastewater treatment and research in order to shorten analysis time.

3, consume medicament in the analytic process in order to save.In traditional analytical approach, because the consumption of heavy dose of medicament, not only expense increases, and causes secondary pollution.

4, in order to reduce the consumption of electrolysis, particularly be in the summer of high temperature, eliminating the electric furnace that discharges a large amount of heats is highly significant.

5, in order to reduce area occupied and analytical equipment instrumentation in the analytic process.

6, in order to improve accuracy and the repeatability of analyzing data.

This instrument effect

1, analysis time is short: can analyze 6 single samples simultaneously for sewage, average 5 minutes of each sample at every turn.

2, easy and simple to handle, owing to eliminated the backflow digestion process, operation is greatly simplified.

3, the reagent consumption is few, and operation semi-automation.

4, for CL ^-The eliminating of ion interference, water sample need not given processing.

5, the analysis time of sample and COD value size is irrelevant.

6, volume of water sample and COD value are irrelevant, only greater than the dilution process of carrying out of 1000mg/l.

7, the good reproducibility of analysis result.

8, analysis result and standard law have good consistance.

Content of the present invention.

1, measuring principle: the mixed liquor of a certain proportion of elutriation and special reagent A and reagent C carries out rapid reaction in thermostatic oven, as the K of oxygenant ₂Er ₂O ₇The reaction back produces Cr ³⁺Ion.The Cr that produces ³⁺The concentration of reductive pollutants is proportional in ion concentration and the water sample.Reacted mixed liquor with carry out potential measurement after reagent D is mixed.The potential measurement value is represented with the form of COD.Special trial-production A, C, D, be respectively oxygenant, composite catalyst and current potential synergistic agent.

2, the structure of this instrument: instrument is made up of main frame, magnetic agitation four, well heater and printer etc.

Fig. 1, be temperature-control circuit figure.Form bridge for measuring temperature by platinum resistance Rt trimmer potentiometer Rw and R.V when electric bridge is uneven ₀Voltage output will be arranged, V ₀Size and the positive and negative duty that is determining the SCR trigger, reach the purpose of temperature control.The power supply of well heater and temperature control line have private jack and instrument to get in touch.

Fig. 2, be regularly and the alarm circuit block diagram.50 or 60H of AC power ₂Sine voltage, through shaping amplify and 50 or 60 frequency divisions after, obtain H ₂The timer timing is sent in the pulse of/S.In 24 hours, establish the amount of the giving time arbitrarily or timing is set arbitrarily in 59-0 divides, when giving the arrival of the time of putting or timing, promote news and ring circuit generation acoustic signal.

Fig. 3 is the detection system block scheme, and probe is made up of platinum electrode and mercurous chloride electrode, and its potential change is amplified through amplifier, sends into display after the A/D converter conversion, directly display result.

3, assay method:

In reaction tube, measure the 2.5ml water sample, add the 0.6ml reagent A, slowly add reagent C and in 165 ℃ ± 1 ℃ constant temperature oven, heated 10 minutes.When the news Chinese percussion instrument is called out, take out reaction tube, cool off after 2 minutes, add the 20ml reagent D, carry out potential measurement, printer is directly got tested COD value.This value is the determination of sewage value.

For the water purification water sample, get 10ml in reaction tube, add 1ml0.01NKMnO ₄Solution and 0.5ml(1+3) sulfuric acid solution is 100 ℃ of constant temperature 30 minutes.When the news Chinese percussion instrument is called out, take out reaction tube; Add the 20ml reagent E and carry out potential measurement, printer is directly got detected water sample COD value.

4, embodiment

A, instrument and standard law are measured the contrast experiment of COD.

The COD value and the oxygenation efficiency of a, various chemical substances are got various chemical substance, and the solution that is mixed with 100mg/l compares experiment.Experimental result such as table 1.

The COD value and the oxygenation efficiency of the various chemical substances of table 1

As can be seen from Table 1, the COD value of instrument and various chemical substances that standard law is surveyed and oxygenation efficiency have good consistance.

B, to various industrial sewages and sanitary sewage, the correlation data such as the table 2 of instrument and standard law measured result.

Table 2, instrument and standard law are measured COD result

Can find out that from table 2 instrument and standard law measured result have good comparability and consistance.

B, relative standard deviation:

Get two different actual water sample of COD value, carry out 10 times continuously and analyze result such as table 3

Table 3, standard deviation calculation result

As can be seen from Table 3, be that standard deviation or relative standard deviation all are very little.

C, to Cl ^-The antijamming capability of ion.When this instrument is normally measured, Cl ^-Ion concentration is to work as Cl to the influence that COD measures ^-Ion concentration does not have obviously influence to the COD value during less than 100mg/l, during greater than 1000mg/l, influences bigger.

D, measurement range:

Little value COD0.3-15mg/l(is suitable for water purification).

Big value COD15-1000mg/l(is suitable for sewage).

E, this instrument minimum detectability amount:

For little value COD is 0.3mg/l.For big value COD is 15mg/l.

Claims (4)

1, the present invention is a chemical oxygen consumption (COC) fast measuring instrument, it is characterized in that using reactant liquor in the aluminum solid heater heats reaction tube, does not have the quick digestion process of backflow, and reacted reactant liquor carries out current potential and detects, and display directly shows measured result.

2, claim 1 is the metallic aluminium manufacturing according to claim solid well heater, once can put 6 reaction tubes, and platinum resistance is as temperature element.

3, claim 3, according to claim 1, reaction tube is diameter 16mm, the pyroceram manufacturing of long 130mm.

4, claim 4, according to claim 1, the current potential detection is the potential change by platinum electrode and mercurous chloride electrode, amplifies through amplifier, the A/D converter conversion directly shows measured result.