CN105352898B - A kind of determining amount method based on spectroscopic methodology COD detections - Google Patents

A kind of determining amount method based on spectroscopic methodology COD detections Download PDF

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CN105352898B
CN105352898B CN201510661778.1A CN201510661778A CN105352898B CN 105352898 B CN105352898 B CN 105352898B CN 201510661778 A CN201510661778 A CN 201510661778A CN 105352898 B CN105352898 B CN 105352898B
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turbidity
cod
testing liquid
absorption spectrum
absorbance
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CN105352898A (en
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王晓萍
胡映天
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文一章
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ZHEJIANG VEELANG ENVIRONMENT TECHNOLOGY Co.,Ltd.
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Zhejiang University ZJU
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Abstract

A kind of determining amount method based on spectroscopic methodology COD detections of disclosure of the invention, comprises the following steps：(1) absorption spectrum of testing liquid is obtained；(2) absorption spectrum during the current turbidity effect of the testing liquid in calculation procedure (1)；(3) peak drop amendment is carried out to the absorption spectrum of the testing liquid in step (1)；The determining amount method of the present invention introduces factor to affect KN(λ) characterizes influence of the turbidity material to organic molecule optical absorption, utilizes KNWith the linear approximate relationship and K of COD titer absorbancesNThe valley of (λ) establishes K with the negative exponent variation relation of turbidityN(λ) model, to correct the peak drop directly deducted in turbidity bias control method, and the foundation of model has environmental suitability, improves precision and the flexibility of COD measurements.

Description

A kind of determining amount method based on spectroscopic methodology COD detections
Technical field
The present invention relates to water quality inspection technique field, more particularly to a kind of determining amount side based on spectroscopic methodology COD detections Method.
Background technology
In monitoring water environment, COD (COD) is an important water quality index, and it reflects water body and reduced The pollution level of property organic matter.《Water environment quality standard》(GB3838-2002)、《Drinking Water source quality mark It is accurate》(CJ3020-93)、《Standards for drinking water quality》Etc. (GB5749-2006) all the limitation of COD concentration is done in national standard Gone out clear and definite regulation, thus to COD it is accurate, easily and fast detect it is extremely important.
At present, COD detection method has chemical method and physical method, and wherein chemical method is mainly dichromate titration (GB11914-89) and permanganate method (GB11892-89), these methods there is time of measuring it is long, need to consume reagent, deposit Secondary pollution, use cost is high the shortcomings of.Physical method refers mainly to ultraviolet-visible (UV-VIS) absorption spectrometry, has real When, quick, online, original position, agent of being excused from an examination, low cost, highly reliable, non-secondary pollution the advantages that, be always that home and abroad environment monitors The study hotspot in field.
However, carrying out the physical method of COD detections using UV-VIS absorption spectrometries, larger technological difficulties be present.This It is because influence wave band of the different component to absorption spectrum is often present overlapping (i.e. cross sensitivity) in water so that prediction process is deposited Interfering, causing prediction deviation.Turbidity such as water body can influence COD prediction, because being suspended present in actual water sample Particle can be to light scattering, absorb and produce turbid phenomenon (i.e. water turbidity), it is turbid although COD absworption peak is in ultraviolet band Degree can influence the full wave absorption characteristics of UV-VIS and have stronger attenuation effect to light in ultra-violet (UV) band, therefore determining amount is particularly It is important.
Although turbidity has been subjected to widely paying attention to as the COD important factor in order measured, determining amount is also many Scholar proposes, but is mentioned for the specific algorithm of determining amount less.The determining amount method being suggested at present, greatly Cause can be divided into two classes：First, COD is predicted with the variation relation of turbidity relative to the prediction error of actual value by establishing COD Value is modified；Second, the method amendment absorption spectrum by deducting turbidity baseline.Although first kind method is simple, not Have and be inherently eliminated the influence that turbidity is brought but only considered numerical value mapping relations, and need substantial amounts of test experiments and Data are supported.For the second class method, current most of methods are all the simple operation on doing mathematicses, do not consider water The mechanism that influences each other of middle material composition, so compensation result still suffers from relative to absorption spectrum curve of the reality without turbidity solution Relatively large deviation.It would therefore be desirable to find a kind of more excellent determining amount method, can correct inclined in the second class method Difference, improve COD prediction accuracy.
The content of the invention
The invention provides a kind of determining amount method based on spectroscopic methodology COD detections, COD accuracy of detection is effectively improved, And using flexible, strong adaptability.
A kind of determining amount method based on spectroscopic methodology COD detections, comprises the following steps：
(1) absorption spectrum of testing liquid is obtained；
(2) absorption spectrum during the current turbidity effect of the testing liquid in calculation procedure (1)；
(3) peak drop amendment is carried out to the absorption spectrum of the testing liquid in step (1), detailed process is as follows：
3-1, turbidity standard and COD standard liquids mixed, it is mixed to obtain that multigroup COD concentration is identical, turbidity value is different Solution is closed as sample solution；
3-2, by formula (1), the factor to affect K of sample solution in calculation procedure 3-1N(λ),
A (λ)=KN(λ)ACOD(λ)+Atur(λ) (1)
Wherein, A (λ) be sample solution absorbance, ACOD(λ) and Atur(λ) is respectively the COD marks corresponding to sample solution The absorbance of quasi- liquid and turbidity standard, KN(λ) is factor to affect；
3-3, the K according to all sample solutions being calculated in step 3-2N(λ), obtain each KNThe valley of (λ) is K, is led to Cross negative exponential curve fitting and establish variation model Ks (t) of the valley K with turbidity；
3-4, according to trough valley K both sides KNHave with sample solution near between identical COD COD titer absorbances Liny sexual intercourse, simulates KNWith the variation model K of wavelengthN(λ)；
3-5, by KN(λ) substitutes into formula (1), the absorbance spectrum calculation formula after being compensated by inverse operation：
A'COD(λ)=(A'(λ)-Atur'(λ))/KN(λ) (2)
Wherein, A'COD(λ) be testing liquid determining amount after absorbance, A'(λ) be testing liquid absorbance, Atur' (λ) is turbidity absorbance of the testing liquid under current turbidity, KN(λ) is the variation model for the factor to affect that simulation obtains；
According to the variation model K (t) in the current turbidity value and step 3-3 of testing liquid, the valley of testing liquid is obtained K, the K of testing liquid is then obtained according to step 3-4N(λ)；
By the K of testing liquidN(λ), the A'(λ of the testing liquid obtained in step (1)) and step (2) in be calculated Testing liquid Atur' (λ) is substituted into formula (2), the A' of the absorbance after being compensatedCOD(λ)。
In theory, langbobier law meets sumproperties：
Wherein, KCODAnd KturRespectively COD and turbidity absorption coefficient, C and T are respectively COD concentration (mg/L) and turbidity (NTU), L is light path.Then turbidity standard and COD standard liquids mixing mixed solution absorbance should be equal to turbidity and Each absorbance contributes sum to COD, i.e.,：
A、ACODAnd AturThe respectively absorbance of mixed solution, COD titers and turbidity standard, should at different wave length Meet：
A (λ)=ACOD(λ)+Atur(λ) (3)
However, actually cause sky because suction-operated of the turbidity particle to organic molecule makes molecule coplanarity be deteriorated Between steric hindrance, the conjugated system of molecule is destroyed, and reduces its absorption to light.If according to formula (3) to mixed solution Absorption spectrum curve does direct baseline deduction, and the obtained curve of spectrum has peak drop, and the peak drop degree at different wave length is different, Therefore the absorbance of mixed solution be not the simple of each materials absorbed light degree contribution plus and.
Therefore, it is necessary to peak drop amendment be carried out to the absorption spectrum of testing liquid, here, becoming present invention introduces one with wavelength The factor to affect K of changeN∈ [0,1], to characterize influence of the turbidity material to COD optical absorptions, obtain formula (1), KNSmaller table Bigger, the K of bright influenceNIt is without influence close to 1：
A (λ)=KN(λ)ACOD(λ)+Atur(λ) (1)
Wherein, A (λ) is by the total absorbance of the revised sample solution of peak shifting, ACOD(λ) and Atur(λ) is respectively COD The absorbance of titer and turbidity standard, KN(λ) is factor to affect.
It is theoretical more than, using formula (1) to the absorption spectrum of sample solution calculate KN(λ), and can by experiment Know, the K near the absworption peak of the COD titers with sample solution with identical COD concentrationN(λ) is just trough, in its both sides KN There is approximate linear relationship, the bigger K of absorbance of standard COD solution respectively between the absorbance of standard COD solutionNMore Small, this shows that turbidity material Potassium Hydrogen Phthalate molecule occurs the centre wavelength influence maximum of energy level transition, in the wavelength Both sides energy level transition probability diminishes, and influence of the turbidity to Potassium Hydrogen Phthalate also tapers into；
In addition, turbidity is bigger, the influence to COD optical absorptions is bigger, KNValley also reduce therewith.Therefore, pass through Carry out negative exponential curve fitting and establish KNValley, can be with by the current turbidity of water sample to be measured calculating K with the variation model of turbidityN The valley of (λ), recycle trough both sides KNLinear approximate relationship between COD titer absorbances, simulates KNBecome with wavelength The model K of changeN(λ), thus, by KN(λ) substitutes into the absorbance spectrum after formula (1) can be compensated by inverse operation：
A'COD(λ)=(A'(λ)-Atur'(λ))/KN(λ) (2)
In order to reduce the storage capacity of system data, it is preferred that in step (2), when the current turbidity of testing liquid acts on The computational methods of absorption spectrum are as follows：
2-1, the absorption spectrum for obtaining the different turbidity standard of multiple turbidity；
2-2, every absorption spectrum in step 2-1 is normalized, formula is as follows：
Wherein, AN(λ) is the absorption spectrum of turbidity standard, AmaxAnd AminIt is the maximum and minimum value of absorbance, ψ (λ) is the curve of spectrum after normalization, and λ is wavelength；
2-3, the normalization light spectral curve that step 2-2 is calculated are averaging, and obtain normalizing spectrumAs mark The curve of spectrum of quasi- turbidity；
The extinction of some wavelength points of the absorption spectrum of testing liquid on visible light wave range in 2-4, obtaining step (1) Degree, calculate the absorbance of acquisition relative to corresponding wavelength atScaling, and ask the average value of scaling to carry out table Levy the current turbidity of the testing liquid；
2-5, by the average value of the scaling in step 2-4 withIt is overall to be multiplied, obtain the current of the testing liquid Absorption spectrum when turbidity acts on.
In the prior art because the spectra collection experimental quantities to standard turbidity solution are always limited, thus can only obtain from The standard absorption curve of spectrum of turbidity is dissipated, also current turbidity approximation discrete turbidity value can only be arrived when deducting turbidity baseline On.In addition, the standard absorption spectroscopic data for storing different turbidity, data volume are huge.
And the present invention need to only store an average normalization light spectral curve data and be used to calculate testing liquid, without depositing The specific spectroscopic data of different turbidity is stored up, greatly reduces the data volume of storage.
And by visible light wave range corresponding wavelength, calculating water sample absorption spectrum to be measured relative to normalization spectrum Scaling characterizes turbidity, and be multiplied with scaling with normalization spectrum turbidity independent role current come dynamic analog when Absorption spectrum curve.The method applicability of this dynamic analog turbidity curve of spectrum is strong, without quantifying to arrive by turbidity measurements The known turbidity curve of spectrum is obtained on some specific turbidity value, improves precision and flexibility.
In order to further improve the precision of COD measurements, it is preferred that in step (3), substitute into the A (λ) of formula (1) and substitute into The A'(λ of formula (2)) it is to move revised absorption spectrum by peak, peak moves amendment and comprised the following steps：
4-1, multigroup known turbidity and the turbidity standard of COD concentration and the mixed solution of COD titers are prepared, and gathered The absorption spectrum of each mixed solution；
The blue shift size of each mixed solution in 4-2, calculation procedure 4-1, blue shift size is established with turbidity by curve matching The mathematical modeling of change；
4-3, the mathematical modeling by step 4-2, according to the current turbidity for the testing liquid being calculated in step (2) Value, the blue shift of testing liquid is calculated；The blue shift of sample solution is calculated according to the standard turbidity value of sample solution；
4-4, the absorption spectrum of sample solution and testing liquid done accordingly according to the blue shift being calculated in step 4-3 It is mobile, obtain the absorption spectrum that peak moves revised sample solution and testing liquid.
By experiment, if using the absorption spectrum curve of current turbidity as baseline, and to the absorption of testing liquid Spectrum does direct baseline deduction, and obtained curve exists to shortwave compared with corresponding standard COD solution absorption spectra curves The skew in direction is blue shift.
Therefore, the model that blue shift size changes with turbidity can be established by curve matching, water sample to be measured is calculated turbid I.e. using the size of the model prediction blue shift after degree, and the curve of spectrum is integrally done to corresponding movement.Due to actual water sample Component comparison is complicated, and blue shift caused by the interaction of material inside influences to differ with titer even blue in different water samples Shifting deviation is very small, but still mark experiment can be built to the specific water sample of locality according to actual conditions with this method, establishes blue shift With turbidity change model and using the model carry out move peak amendment.
The present invention establishes blue shift size and the relation of turbidity using priori experiment and data, is come in advance with this in compensation process Survey blue shift and spectrum is integrally carried out to move peak amendment, repair the blue shift defect in direct deduction turbidity bias control method.Separately Outside, different blue shift models is established to different water environments, there is certain water environment adaptability.
In order to facilitate the progress of experiment, it is easy to complete to move peak amendment, it is further preferred that preferably, the turbidity standard Liquid uses formal hydrazine turbidity standard, and COD standard liquids use Potassium Hydrogen Phthalate COD standard liquids.Now blue shift shows As if the hydrogen bond as caused by the carboxyl in highly polar the molecule hydrazine and Potassium Hydrogen Phthalate in turbidity standard formal hydrazine draws Rise, because hydrogen bond can influence n- π * energy level transitions, make R band absworption peaks that blue shift occur.With the increase of turbidity, the concentration of hydrazine increases Greatly, the interference increase of hydrogen bond, blue shift size are also in rising trend.
In order in peak drop amendment, improve the accuracy of amendment, it is preferred that in step (3), the sample solution of configuration COD is 30~70mg/L.
In order that the accuracy of the absorbance of the current turbidity obtained improves, it is preferred that in step 2-4, the visible ray The wave-length coverage of spectrum is 400~600nm.
In order to accurately obtain variation model KN(λ), it is preferred that in step 3-4,
The linear approximate relationship is in 265~280nm and 280~300nm in wave-length coverage.Within the above range, Trough valley K both sides KNWith obvious linear relationship between COD titer absorbance of the sample solution with identical COD.
Beneficial effects of the present invention：
The determining amount method of the present invention introduces factor to affect KN(λ) characterizes turbidity material to organic molecule optical absorption Influence, utilize KNWith the linear approximate relationship and K of COD titer absorbancesNThe valley of (λ) changes with the negative exponent of turbidity to close System, establishes KN(λ) model, to correct the peak drop directly deducted in turbidity bias control method, and the foundation of model has environment Adaptability, improve precision and the flexibility of COD measurements.
Brief description of the drawings
Fig. 1 is the abosrption spectrogram for the mixed solution that COD concentration is 50mg/L and turbidity is different.
Fig. 2 is the abosrption spectrogram of different turbidity standards.
Fig. 3 is turbidity abosrption spectrogram of the different turbidity standards after normalization.
Fig. 4 is blue shift size and curve matching figure under different turbidity.
Fig. 5 is that the mixed solution that COD concentration is identical, turbidity is different directly deducts the absorption spectrum after standard turbidity baseline Figure.
Fig. 6 is the K of wavelength mixed solution of different turbidity in the range of 250-330nmN(λ) with wavelength variation diagram.
Fig. 7 is KNChange and its curve matching figure of the valley with turbidity.
Fig. 8 is wavelength K in the range of 265-280nmNWith the variation diagram of COD standard liquid absorbances.
Fig. 9 is abosrption spectrogram of the testing liquid after determining amount.
Embodiment
In the present embodiment, turbidity standard uses formal hydrazine titer, and COD standard liquids use Potassium Hydrogen Phthalate COD standard liquids.
The determining amount method based on spectroscopic methodology COD detections of the present embodiment, comprises the following steps：
(1) turbidity standard and COD standard liquids are mixed, it is 50mg/L to obtain COD concentration, turbidity value is respectively 0, For 5NTU, 10NTU, 20NTU, 30NTU, 40NTU and 50NTU mixed solution as testing liquid, Fig. 1 is above-mentioned several prepare liquids The abosrption spectrogram of body.
(2) absorption spectrum in calculation procedure (1) during the current turbidity effect of all testing liquids, when current turbidity acts on Absorption spectrum computational methods it is as follows：
2-1, obtain the suction that turbidity is respectively 5NTU, 10NTU, 20NTU, 30NTU, 40NTU and 50NTU turbidity standard Spectrum is received, as shown in Figure 2；
2-2, every absorption spectrum in step 2-1 is normalized, obtains the suction of the turbidity after normalization Spectrogram is received, as shown in figure 3, normalized formula is as follows：
AN(λ) is the absorption spectrum of turbidity standard, AmaxAnd AminIt is the maximum and minimum value of absorbance, ψ (λ) is to return The curve of spectrum after one change, λ is wavelength；
2-3, the normalization light spectral curve that step 2-2 is calculated are averaging, and obtain normalizing spectrum,As mark The curve of spectrum of quasi- turbidity；
The extinction of some wavelength points of the absorption spectrum of testing liquid on visible light wave range in 2-4, obtaining step (1) Degree, calculate the absorbance of acquisition relative to corresponding wavelength atScaling, and ask the average value of scaling to carry out table Levy the current turbidity of the testing liquid；
2-5, by the average value of the scaling in step 2-4 withIt is overall to be multiplied, you can to obtain working as the testing liquid Absorption spectrum during preceding turbidity effect.
Fig. 1 illustrates the absorption spectrum curve of different turbidity (5,10,20,30,40,50NTU) titers.It can be seen that not Curve shape with turbidity is roughly the same, and the spectrum in Fig. 1 is illustrated in overall amplification, Fig. 3 with the increase curve of turbidity Normalized curve of the curve after formula (1) processing, it is found that the normalization light spectral curve of different turbidity essentially coincides, can use it Averaged spectrum is as normalization linear functionTo characterize the normalization absorption spectrum of turbidity standard.
(3) peak shifting amendment is carried out to the absorption spectrum of all testing liquids in step (1), detailed process is as follows：
3-1, multigroup known turbidity and the turbidity standard of COD concentration and the mixed solution of COD titers are prepared, and gathered The absorption spectrum of each mixed solution；
The blue shift size of each mixed solution in 3-2, calculation procedure 3-1, blue shift size is established with turbidity by curve matching The mathematical modeling of change, fitting result are as shown in Figure 4；
3-3, the mathematical modeling by step 3-2, according to the current turbidity for the testing liquid being calculated in step (2) Value, the blue shift of testing liquid is calculated；
3-4, the absorption spectrum of testing liquid in step (1) done accordingly according to the blue shift being calculated in step 3-3 It is mobile.
Blue-shifted phenomenon is by the carboxylic in highly polar the molecule hydrazine and Potassium Hydrogen Phthalate in turbidity standard formal hydrazine Caused by hydrogen bond caused by base, because hydrogen bond can influence n- π * energy level transitions, make R band absworption peaks that blue shift occur.With turbidity Increase, the concentration increase of hydrazine, the interference increase of hydrogen bond, blue shift size are also in rising trend.As shown in figure 4, illustrate different turbid Blue shift situation under degree, is represented in figure with the point of black.Curve is the result that these points are carried out with negative exponential curve fitting.From It can see in figure, as turbidity becomes big, blue shift amplitude becomes big, and it subtracts with the change of turbidity after blue shift increases to a certain extent It is slow final almost unchanged.
(4) peak drop amendment is carried out to the absorption spectrum for moving revised all testing liquids in step (3) by peak, specifically Process is as follows：
4-1, turbidity standard and COD standard liquids mixed, it is 50mg/L to obtain COD value, turbidity value is respectively 0, 5NTU, 10NTU, 20NTU, 30NTU, 40NTU and 50NTU mixed solution are as sample solution；
4-2, by formula (2), the factor to affect K of sample solution in calculation procedure 4-1N(λ),
A (λ)=KN(λ)ACOD(λ)+Atur(λ) (2)
Wherein, A (λ) is that sample solution passes through the shifting revised absorbance in peak, and process is identical with testing liquid, ACOD(λ) and AturThe absorbance of COD titers and turbidity standard corresponding to (λ) difference sample solution, KN(λ) is factor to affect；
4-3, the K according to each sample solution being calculated in step 4-2N(λ), as shown in fig. 6, each KNThe valley of (λ) is K, variation model Ks (t) of the valley K with turbidity is established by curve matching, as shown in Figure 7；
4-4, according to trough valley K both sides KNLinear approximate relationship between the COD titer absorbances for being zero with turbidity, Simulate KNWith the variation model K of wavelengthN(λ), linear approximate relationship is as shown in Figure 8；
4-5, by KN(λ) substitutes into formula (3), the absorbance spectrum calculation formula after being compensated by inverse operation：
A'COD(λ)=(A'(λ)-Atur'(λ))/KN(λ) (3)
Wherein, A'COD(λ) is the absorbance after determining amount, A'(λ) it is the suction that revised testing liquid is moved by peak Luminosity, Atur' (λ) be turbidity absorbance of the testing liquid under current turbidity, KN(λ) is the change for the factor to affect that simulation obtains Change model.
4-6, substituted into step 4-3 according to the current turbidity value of testing liquid, obtain the valley K, Ran Hougen of testing liquid The K of testing liquid is obtained according to the linear approximate relationship in step 4-4N(λ), by the K of testing liquidN(λ), obtain in step (1) The A'(λ of testing liquid), and the A for the testing liquid being calculated in step (2)tur' (λ) substitution formula (3), it is compensated The A' of absorbance afterwardsCOD(λ)。
Fig. 5~8 illustrate factor to affect KNThe changing rule of (λ), Fig. 5 illustrate 50mg/L COD and different turbidity (0, 5,10,20,30,40,50NTU) absorption spectrum of the mixed solution after directly deducting turbidity standard absorbance, absworption peak Blue shift and peak drop deviation are more apparent, and turbidity more large deviation is bigger.Fig. 6 is represented near COD titers absworption peak (280nm) KNWith the change curve of wavelength, K at COD absworption peaks in figureNThere is valley in (λ), with COD absorbances to peak value both sides decline, KN It is gradually increasing finally close to 1.Fig. 7 is K under different turbidityNThe valley of (λ), represented in figure with the point of black, curve is pair It carries out the result of negative exponential curve fitting.It can be seen that as turbidity increases, KN(λ) valley reduces, and reduces Speed is gradually slack-off.Fig. 8 is illustrated in the range of 265-280nm, KN, can from figure with the change of COD titer absorbances Go out, KNAbsorbance with the COD standard liquids that turbidity is 0 is in approximately linear variation tendency, and COD standard liquid absorbances are bigger, KN It is smaller.
Fig. 9 represents the absorption spectrum after determining amount.From Fig. 1 and Fig. 9 contrast as can be seen that with turbid before compensation Degree increase, absworption peaks of the COD 280nm at is gradually submerged so that None- identified, and the blue shift that brings of the addition of turbidity with Peak drop is all more obvious；The absorption spectrum of mixed liquor almost overlaps with the absorption spectrum of COD titers after compensation, at 280nm Peak displays, and compensation effect is preferable.

Claims (7)

  1. A kind of 1. determining amount method based on spectroscopic methodology COD detections, it is characterised in that comprise the following steps：
    (1) absorption spectrum of testing liquid is obtained；
    (2) absorption spectrum during the current turbidity effect of the testing liquid in calculation procedure (1)；
    (3) peak drop amendment is carried out to the absorption spectrum of the testing liquid in step (1), detailed process is as follows：
    3-1, turbidity standard and COD standard liquids mixed, it is molten to obtain the mixing that multigroup COD concentration is identical, turbidity value is different Liquid is as sample solution；
    3-2, by formula (1), the factor to affect K of sample solution in calculation procedure 3-1N(λ),
    A (λ)=KN(λ)ACOD(λ)+Atur(λ) (1)
    Wherein, A (λ) be sample solution absorbance, ACOD(λ) and Atur(λ) respectively the COD titers corresponding to sample solution and The absorbance of turbidity standard, KN(λ) is factor to affect；
    3-3, the K according to all sample solutions being calculated in step 3-2N(λ), obtain each KNThe valley of (λ) is K, by negative Variation model Ks (t) of the valley K with turbidity is established in exponential curve fitting；
    3-4, according to trough valley K both sides KNThere is the proximal line between identical COD COD titer absorbances with sample solution Sexual intercourse, simulate KNWith the variation model K of wavelengthN(λ)；
    3-5, by KN(λ) substitutes into formula (1), the absorbance spectrum calculation formula after being compensated by inverse operation：
    A'COD(λ)=(A'(λ)-Atur'(λ))/KN(λ) (2)
    Wherein, A'COD(λ) be testing liquid determining amount after absorbance, A'(λ) be testing liquid absorbance, Atur'(λ) The turbidity absorbance for being testing liquid under current turbidity, KN(λ) is the variation model for the factor to affect that simulation obtains；
    According to the variation model K (t) in the current turbidity value and step 3-3 of testing liquid, the valley K of testing liquid is obtained, so The K of testing liquid is obtained according to step 3-4 afterwardsN(λ)；
    By the K of testing liquidN(λ), the A'(λ of the testing liquid obtained in step (1)) and step (2) in be calculated treat Survey the A of liquidtur' (λ) is substituted into formula (2), the A' of the absorbance after being compensatedCOD(λ)。
  2. 2. the determining amount method as claimed in claim 1 based on spectroscopic methodology COD detections, it is characterised in that in step (2), The computational methods of absorption spectrum during the current turbidity effect of testing liquid are as follows：
    2-1, the absorption spectrum for obtaining the different turbidity standard of multiple turbidity；
    2-2, every absorption spectrum in step 2-1 is normalized, formula is as follows：
    <mrow> <mi>&amp;psi;</mi> <mrow> <mo>(</mo> <mi>&amp;lambda;</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mrow> <msub> <mi>A</mi> <mi>N</mi> </msub> <mrow> <mo>(</mo> <mi>&amp;lambda;</mi> <mo>)</mo> </mrow> <mo>-</mo> <msub> <mi>A</mi> <mi>min</mi> </msub> </mrow> <mrow> <msub> <mi>A</mi> <mrow> <mi>m</mi> <mi>a</mi> <mi>x</mi> </mrow> </msub> <mo>-</mo> <msub> <mi>A</mi> <mi>min</mi> </msub> </mrow> </mfrac> <mo>,</mo> </mrow>
    Wherein, AN(λ) is the absorption spectrum of turbidity standard, AmaxAnd AminIt is the maximum and minimum value of absorbance, ψ (λ) is to return The curve of spectrum after one change, λ is wavelength；
    2-3, the normalization light spectral curve that step 2-2 is calculated are averaging, and obtain normalizing spectrumIt is turbid as standard The curve of spectrum of degree；
    The absorbance of some wavelength points of the absorption spectrum of testing liquid on visible light wave range in 2-4, obtaining step (1), meter Calculate obtain absorbance relative to corresponding wavelength atScaling, and ask the average value of scaling to be treated to characterize this Survey the current turbidity of liquid；
    2-5, by the average value of the scaling in step 2-4 withIt is overall to be multiplied, obtain the current turbidity of the testing liquid Absorption spectrum during effect.
  3. 3. the determining amount method as claimed in claim 1 or 2 based on spectroscopic methodology COD detections, it is characterised in that step (3) In, substitute into the A (λ) of formula (1) and substitute into the A'(λ of formula (2)) it is to move revised absorption spectrum by peak, peak moves amendment bag Include following steps：
    4-1, multigroup known turbidity and the turbidity standard of COD concentration and the mixed solution of COD titers are prepared, and gathered each mixed Close the absorption spectrum of solution；
    The blue shift size of each mixed solution in 4-2, calculation procedure 4-1, blue shift size is established by curve matching and changed with turbidity Mathematical modeling；
    4-3, the mathematical modeling by step 4-2, according to the current turbidity value for the testing liquid being calculated in step (2), meter Calculation obtains the blue shift of testing liquid；The blue shift of sample solution is calculated according to the standard turbidity value of sample solution；
    4-4, the absorption spectrum of sample solution and testing liquid done into corresponding shifting according to the blue shift being calculated in step 4-3 It is dynamic, obtain the absorption spectrum that peak moves revised sample solution and testing liquid.
  4. 4. the determining amount method as claimed in claim 1 or 2 based on spectroscopic methodology COD detections, it is characterised in that the turbidity Titer uses formal hydrazine turbidity standard, and COD standard liquids use Potassium Hydrogen Phthalate COD standard liquids.
  5. 5. the determining amount method as claimed in claim 1 or 2 based on spectroscopic methodology COD detections, it is characterised in that step (3) In, the COD of the sample solution of configuration is 30~70mg/L.
  6. 6. the determining amount method as claimed in claim 2 based on spectroscopic methodology COD detections, it is characterised in that in step 2-4, The wave-length coverage of the visible spectrum is 400~600nm.
  7. 7. the determining amount method as claimed in claim 1 or 2 based on spectroscopic methodology COD detections, it is characterised in that in step 3- In 4, the linear approximate relationship is in 265~280nm and 280~300nm in wave-length coverage.
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