CN105675521A - Method and detecting device for online detecting water pH value based on sensitive membranes - Google Patents

Abstract

The invention provides a method for online detecting the water pH value based on sensitive membranes.The method includes the following steps that the sensitive membranes are prepared; buffer solutions with the different pH values are prepared, and absorption spectra of the sensitive membranes are obtained; the molar-absorption-coefficient ratios e1, e2 and e3 and multiple absorbance ratios R are calculated; linear regression curves are prepared through the molar-absorption-coefficient ratios and the multiple absorbance ratios to obtain the slope 1/n and the intercept pK<a> of the linear regression curves; the sensitive membranes are immersed into to-be-detected water, and the absorbance ratio R under the present condition is calculated; the molar-absorption-coefficient ratios e1, e2 and e3, the slope 1/n, the intercept pK<a> and the absorbance ratio R<x> under the present condition are substituted into the formula to calculate the pH value of the to-be-detected water.The invention further provides a detecting device for online detecting the water pH value based on the sensitive membranes.The method has the advantages of being high in detection accuracy and flexible in use.

Description

A kind of method based on sensitive membrane on-line checkingi water pH value and detection device

Technical field

The invention belongs to environmental monitoring technology field, specifically, particularly relate to a kind of method based on sensitive membrane on-line checkingi water pH value and detection device.

Background technology

PH value is the important parameter of water quality monitoring (WQM) and evaluation, and monitoring result circulates all significant for ECOLOGICAL ENVIRONMENTAL MONITORING, Ocean acidification, Carbon budget, geochemistry.

In prior art, the method for on-line monitoring water pH value is mainly electrode method and light-intensity method. The pH electrode volume used in the measurement of electrode method is little, energy consumption is low, reusable and survey frequency height, but life-time service current potential can drift about, signal is easily subject to electromagnetic interference, has the defect that precision is low, need to regularly calibrate. And the light-intensity method injected based on indicator adopts multi-wavelength to calculate, there is precision height, exempt from the features such as correction, but appliance requires uses the devices such as pump, valve, flow-through cell, reagent bag, mixing tank to cooperatively interact, having that volume is big, energy consumption height, need regularly to change the shortcomings such as reagent, indicator itself also may can cause the change of solution ph simultaneously. Based on the water pH value detection method of sensitive membrane, have reusable, without the need to advantages such as chemical reagent injections, but the leakage of indicator can affect measuring result, existing Single wavelength assay method has the shortcomings such as measuring accuracy is low simultaneously.

Summary of the invention

The present invention provides a kind of multi-wavelength measuring method based on sensitive membrane on-line checkingi water pH value, overcomes the shortcoming that accuracy of detection in prior art is low, indicator leakage causes measuring result deviation.

The present invention provides a kind of detection method based on sensitive membrane on-line checkingi water pH value, comprises the following steps:

1) sensitive membrane is prepared;

2) the different buffered soln of pH value is configured, by step 1) sensitive membrane prepared is placed in buffered soln, measure and obtaining step 1) absorption spectrum of sensitive membrane prepared, and the alkali state maximum absorption wavelength λ of sensitive membrane is obtained according to the absorption spectrum of described sensitive membrane₁With acid-state maximum absorption wavelength λ₂, obtain wavelength X₁And λ₂Time respectively corresponding absorbance A₁、A₂;

3) as buffered soln pH=11-13, step 2) absorbance A that obtains₁、A₂It is designated as A respectively₁(I^2-)、A₂(I^2-);As buffered soln pH=4-6, step 2) absorbance A that obtains₁、A₂It is designated as A respectively₁(HI^-)、A₂(HI^-); Utilize formula

e₁=ε₁(HI^–)/ε₂(HI^–)=A₁(HI^–)/A₂(HI^–),

e₂=ε₁(I^2–)/ε₂(HI^–)=A₁(I^2–)/A₂(HI^–),

e₃=ε₂(I^2–)/ε₂(HI^–)=A₂(I^2–)/A₂(HI^–),

Obtain molar absorptivity ratio e₁、e₂、e₃;

4) by step 1) sensitive membrane prepared is placed in the buffered soln of pH=6-11 respectively, obtains many group absorbance ratio R, R=A₁/A₂;

5) basisUtilize step 3) the molar absorptivity ratio e that obtains₁、e₂、e₃With step 4) many groups absorbance ratio R of obtaining prepares linear regression curves, obtains the slope 1/n and intercept pK of linear regression curves_a;

6) by step 1) sensitive membrane that obtains immerses water body to be measured, obtains wavelength X₁And λ₂Time respectively corresponding absorbance A_1X、A_2X, obtain the absorbance ratio R under current condition_X, R_X=A_1X/A_2X;

7) by step 3) the molar absorptivity ratio e that obtains₁、e₂、e₃, step 5) and the slope 1/n that obtains and intercept pK_a, step 6) and the absorbance ratio R that obtains_XSubstitute into formulaObtain the pH value of water body to be measured.

Preferably, prepare sensitive membrane by sol-gel method, specifically comprise the following steps:

A. measure distilled water, dehydrated alcohol, HCl, tensio-active agent and tetraethoxy respectively, take pH sensitive agents, at room temperature stir to clarify after mixing;

B. aging 1 to 7 day of sol solutions step a obtained;

C. by spin coating method or soak stagnant crystal pulling method, utilize that step b obtains aging after solution prepare gel-film on the glass sheet; Before preparation, carry out glass sheet surface cleaning activation;

D. the glassy membrane of cleaning, drying sol-gel coating, obtains sensitive membrane.

Preferably, the absorption spectrum measuring sensitive membrane specifically comprises the following steps:

E. configuring pH value is the buffered soln of 5-12, and utilizes glass pH meter to correct;

The glassy membrane of the sol-gel coating f. steps d prepared is placed in the cuvette of the buffered soln accommodating different pH value respectively, utilizes spectrophotometer or spectrograph to measure, obtains the sensitive membrane spectrum of sensitive membrane under different pH condition;

G. according to described sensitive membrane spectrum, the alkali state maximum absorption wavelength λ of preparation sensitive membrane is obtained₁With acid-state maximum absorption wavelength λ₂。

Preferably, step 3 is adopted) computation and measurement parameter specifically comprises the following steps:

I. sensitive membrane being immersed in the vessel accommodating buffered soln, wherein preparing described sensitive membrane pH sensitive agents used is diprotic acid, buffered soln pH=12; Light source provides first, second and third road stabilized light source to export, the wavelength that wherein first via stabilized light source exports equals the alkali state maximum absorption wavelength of described sensitive membrane, the wavelength that 2nd road stabilized light source exports equals the acid-state maximum absorption wavelength of described sensitive membrane, and the wavelength that the 3rd road stabilized light source exports equals reference wavelength; Calculate the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A1、I_B1、I_C1; Calculate absorbance A₁(I^2–) and A₂(I^2–), wherein

Ii. sensitive membrane is immersed in the vessel accommodating buffered soln, buffered soln pH=5; Light source provides first, second and third road stabilized light source to export, the wavelength that first via stabilized light source exports equals the alkali state maximum absorption wavelength of described sensitive membrane, the wavelength that 2nd road stabilized light source exports equals the acid-state maximum absorption wavelength of described sensitive membrane, and the wavelength that the 3rd road stabilized light source exports equals reference wavelength; Calculate the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A2、I_B2、I_C2; Calculate absorbance A₁(HI^–) and A₂(HI^–), wherein

Iii. molar absorptivity ratio e is calculated₁、e₂、e₃, wherein e₁=A₁(HI^–)/A₂(HI^–), e₂=A₁(I^2–)/A₂(HI^–), e₃=A₂(I^2–)/A₂(HI^–);

Iv. absorbance ratio R is obtained; Sensitive membrane is immersed respectively in multiple vessel accommodating buffered soln, wherein buffered soln pH=6～11; Light source assembly provides first, second and third road stabilized light source to export respectively, calculates many corresponding light intensity I of group reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A、I_B、I_C; Calculate and organize absorbance A more₁、A₂, wherein Obtain the absorbance ratio R of sensitive membrane in different pH value buffered soln, R=A₁/A₂。

Detection method proposed by the invention, it is ensured that it is linear that water body measures pH value and absorbancy in the pH value range with indicator discoloration. The pH value of detection only depends on detection water body absorbance ratio R to be measured_XThis single parameter, chromogenic agent can not affect detected value, it is possible to effectively avoids indicator to leak the baseline wander caused.

Invention also provides a kind of detection device based on sensitive membrane on-line checkingi water pH value adopting above-mentioned detection method, comprise light source assembly, optical path component, signals collecting assembly and control unit; Also comprise the first enclosed housing and the 2nd enclosed housing that contact with extraneous water body, and it is provided with the sensitive membrane of pH sensitive agents; Wherein, described light source assembly is arranged in described first enclosed housing, for providing the stabilized light source of multiple wavelength to export; Described optical path component comprises the spectral filter, condensing lens, opticcoupler, optical fiber and the optical window that export corresponding setting with described stabilized light source; Wherein, described optical window comprises the first optical window and the 2nd optical window, is embedded on the corresponding sidewall of the first enclosed housing and the 2nd enclosed housing respectively; Described condensing lens comprises the first condensing lens and the 2nd condensing lens, and described first condensing lens and the 2nd condensing lens are separately positioned in the first enclosed housing and the 2nd enclosed housing; The light that described light source assembly sends is divided into two portions after spectral filter, opticcoupler, and a part, for measuring light, injects sensitive membrane successively after the first condensing lens, the first optical window, extraneous water body; Light through described sensitive membrane is penetrated to signals collecting assembly successively after the 2nd optical window, the 2nd condensing lens; Another part, for ginseng is than light, is penetrated to signals collecting assembly after fiber optic conduction; Described signals collecting assembly is arranged in described 2nd enclosed housing, for carry out opto-electronic conversion and output detections signal to control unit; Described control unit be used for detection signal that Received signal strength acquisition component exports and in the pH value of the extraneous water body of line computation.

Further, described sensitive membrane is arranged between the first enclosed housing and the 2nd enclosed housing and is fixed on described first optical window, the 2nd optical window, quartz or glass.

Preferably, the wavelength that the first via stabilized light source that described light source assembly provides exports equals the alkali state maximum absorption wavelength of described sensitive membrane, the wavelength that 2nd road stabilized light source exports equals the acid-state maximum absorption wavelength of described sensitive membrane, and the wavelength that the 3rd road stabilized light source exports equals described sensitive membrane completely without the wavelength absorbed.

Preferably, described spectral filter comprises first spike filter corresponding with light source assembly, the 2nd spike filter and the 3rd spike filter; The centre wavelength of wherein said first spike filter equals alkali state maximum absorption wavelength, and the centre wavelength of the 2nd spike filter equals acid-state maximum absorption wavelength, and the centre wavelength of the 3rd spike filter equals the centre wavelength of the 3rd road stabilized light source.

Preferably, described signals collecting assembly comprises photorectifier, CCD and/or photomultiplier;Described light source assembly comprises the independent LED, laser and/or the halogen lamp that arrange.

Preferably, described pH sensitive agents is phenol red, toluylene red, m-cresol purple or phenolphthalein.

Detection device based on sensitive membrane on-line checkingi water pH value provided by the present invention, it is not necessary to injection, the integrated level height of added regent, volume is little, energy consumption is low, reusable, be applicable to on-line checkingi.

Accompanying drawing explanation

In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, it is briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the structural representation of detection device first embodiment adopting the method based on sensitive membrane on-line checkingi water pH value proposed by the invention;

Fig. 2 is the sensitive membrane spectrogram obtained in the present invention;

Fig. 3 is the regression curve schematic diagram of preparation in the present invention.

Embodiment

For making the object of the embodiment of the present invention, technical scheme and advantage clearly, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is the present invention's part embodiment, instead of whole embodiments. Based on the embodiment in the present invention, those of ordinary skill in the art, not making other embodiments all obtained under creative work prerequisite, belong to the scope of protection of the invention.

The ultimate principle that the present embodiment is proposed the method based on sensitive membrane on-line checkingi water pH value is as follows: (be designated as H with diprotic acid pH sensitive agents₂I) being example, the pH value of its two grades of ionization constants and water body to be measured is close. H when sensitive membrane contacts with water body, in the sensitive agents being fixedly installed in sensitive membrane and water body⁺Reversible reaction occurs, and ionization generates the HI of acid-state^–With the I of alkali state^2–. This ionization equilibrium can be written as:

Thus can obtain pH value is:

$pH={\mathrm{pK}}_a+{\log }_{10}\frac{\&lsqb;I^{2-}\&rsqb;}{\&lsqb;{\mathrm{HI}}^{-}\&rsqb;}---\left(2\right)$

K in formula_aFor ionization constant (K_a=[H⁺][I^2-]/[HI^-]), pK_a=-log₁₀(K_a)。

The HI of acid-state in water body^–With the I of alkali state^2–Having different spectral signatures, its maximum absorption wavelength is different with molar absorptivity. When the sensitive membrane utilizing sol-gel method to prepare measures pH, the absorbancy that thickness is about 1 μm of sensitive membrane acquisition can be 0.2 0.6, and therefore absorbancy and volumetric molar concentration do not strictly observe Bill's Lambert's law. Namely absorbancy and volumetric molar concentration are not linear, but exponentially relation. So absorbancy calculation formula can be written as:

A₁=ε₁(HI^-)[HI^-]ⁿl+ε₁(I^2-)[I^2-]ⁿl(3)

A₂=ε₂(HI^-)[HI^-]ⁿl+ε₂(I^2-)[I^2-]ⁿl(4)

ε in formula₁(HI^-)、ε₂(HI^-)、ε₁(I^2-)、ε₂(I^2-), be respectively alkali state maximum absorption wavelength λ₁With acid-state maximum absorption wavelength λ₂Time alkali state I^2–, acid-state HI^–Molar absorptivity, n is index coefficient, and l is path length, A₁、A₂It is divided into absorbancy.

Can obtain by formula (3), (4):

$\frac{\&lsqb;I^{2-}\&rsqb;}{\&lsqb;{\mathrm{HI}}^{-}\&rsqb;}=\frac{A_1{\mathrm{\&epsiv;}}_2\left({\mathrm{HI}}^{-}\right)L-A_2{\mathrm{\&epsiv;}}_1\left({\mathrm{HI}}^{-}\right)L}{A_2{\mathrm{\&epsiv;}}_1\left(I^{2-}\right)L-A_1{\mathrm{\&epsiv;}}_2\left(I^{2-}\right)L}=\frac{\frac{A_1}{A_2}-\frac{{\mathrm{\&epsiv;}}_1\left({\mathrm{HI}}^{-}\right)}{{\mathrm{\&epsiv;}}_2\left({\mathrm{HI}}^{-}\right)}}{\frac{{\mathrm{\&epsiv;}}_1\left(I^{2-}\right)}{{\mathrm{\&epsiv;}}_2\left({\mathrm{HI}}^{-}\right)}-\frac{A_1}{A_2}\&times;\frac{{\mathrm{\&epsiv;}}_2\left(I^{2-}\right)}{{\mathrm{\&epsiv;}}_2\left({\mathrm{HI}}^{-}\right)}}---\left(5\right)$

Make R=A₁/A₂, e₁=ε₁(HI^–)/ε₂(HI^–), e₂=ε₁(I^2–)/ε₂(HI^–), e₃=ε₂(I^2–)/ε₂(HI^–), can obtain by formula (2), (5):

$pH={\mathrm{pK}}_a+\frac{1}{n}log10\frac{R-e_1}{e_2-{\mathrm{Re}}_3},---\left(6\right)$

Solid form one timing of pH sensitive agents in sensitive membrane, measuring parameter (molar absorptivity ratio e₁、e₂、e₃With index coefficient n) it is constant. When measuring parameter is determined, pH observed value is only relevant with absorbance ratio R. By formula (6) it will be seen that water body measure and indicator discoloration pH within the scope of pH and absorbancy linear. Absorbance ratio R is by alkali state I in pH sensitive agents^2–, acid-state HI^–The decision of proportion, and unrelated with sensitive agents total amount fixing in sensitive membrane.Under such condition, therefore, pH meter calculation value is unrelated with the sensitive agents total amount fixing state.

When pH value is lower, in sensitive membrane, pH sensitive agents existence form is based on acid-state, now [I^2–]+[HI^–]≈[HI^–]; When pH value is higher, in sensitive membrane, pH sensitive agents existence form is based on alkali state, now [I^2–]+[HI^–]≈[I^2–]. Therefore, when the pH value of buffered soln is lower or higher, in wavelength X₁And λ₂The absorbance A that place obtains₁、A₂A can be designated as respectively₁(HI^-)、A₂(HI^-)、A₁(I^2-)、A₂(I^2-). Owing to concentration is identical with path length, now:

e₁=ε₁(HI^–)/ε₂(HI^–)=A₁(HI^–)/A₂(HI^–)

e₂=ε₁(I^2–)/ε₂(HI^–)=A₁(I^2–)/A₂(HI^–)

e₃=ε₂(I^2–)/ε₂(HI^–)=A₂(I^2–)/A₂(HI^–)

Can be calculated molar absorptivity ratio e₁、e₂、e₃。

Further sensitive membrane is placed in the different buffered soln of pH value, then can measure the many group absorbance ratio R of sensitive membrane in different pH value buffered soln.

According to molar absorptivity ratio e₁、e₂、e₃Absorbance ratio R with obtaining in different pH value buffered soln, utilizes formula (6) can obtain equation of linear regression. Utilize slope and the intercept of equation of linear regression can calculate measuring parameter n and pK in formula (6)_a. Like this, by measuring single parameter, it also it is exactly the pH value that namely absorbance ratio of water body to be measured can calculate water body to be measured.

Below by the first embodiment, the detection method based on sensitive membrane on-line checkingi water pH value provided by the present invention is described further.

First sensitive membrane is prepared. Choosing phenol red as pH sensitive agents, choosing TritonX-100 is tensio-active agent. Measuring 5.0ml distilled water, 5.0ml dehydrated alcohol, the HCl of 3.0ml0.1M, 0.2mlTritonX-100 and 10.0ml tetraethoxy (TEOS), takes 40mg phenol red, at room temperature stirs to clarify after mixing. It is used for glass coating after aging for the sol solution of preparation one day.

Sheet glass (3cm × 0.9cm × 1.1mm) is positioned in concentrated nitric acid 2h, successively with distilled water and washes of absolute alcohol, and dries under 120 DEG C of conditions, must clean the sheet glass activated. By activation after sheet glass be placed on spin coater, surface drip enter 200 μ L aging after sol solutions, and when rotating speed is 1900rpm rotate 30s. Sheet glass after coating is placed on after drying 48h in 40 DEG C of baking ovens, successively utilizes distilled water and washes of absolute alcohol, prepares sensitive membrane.

Utilize 0.2MNaOAc, 0.3MHOAc, 0.2MNa₂HPO₄, 0.3MNaH₂PO₄, 0.05MNa₂B₄O₇, 0.2MH₃BO₃And 0.1MNa₂CO₃Configuration pH value is respectively the buffered soln of 5 12. Buffered soln utilizes glass pH meter to correct, and utilizes 0.1MHCl or 0.1MNaOH that buffered soln is adjusted to required pH value.

The sensitive membrane that sol-gel applies is placed in the cuvette containing different pH buffer respectively, utilizes spectrophotometer or spectrograph to measure, obtain the spectrum of sensitive membrane during different pH value. Shown in Figure 2, by the spectrum of sensitive membrane, HI can be drawn^–And I^2–Maximum absorption wavelength be divided into 445nm, 560nm.

First, second and third light source stable output light source exports, it is preferable that being LED, wherein the centre wavelength of first, second and third light source is about 560nm, 445nm, 810nm respectively. The wavelength that wherein first via stabilized light source exports equals the alkali state maximum absorption wavelength of described sensitive membrane, the wavelength that 2nd road stabilized light source exports equals the acid-state maximum absorption wavelength of sensitive membrane, the wavelength that 3rd road stabilized light source exports equals sensitive membrane completely without the wavelength absorbed, and namely ginseng compares light source.

The method of the detection device on-line checkingi water pH value that employing the present embodiment provides, also comprises the following steps:

1) sensitive membrane is immersed in the vessel accommodating buffered soln, buffered soln pH=12;First, second and third road light source provides stabilized light source to export, and calculates the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A1、I_B1、I_C1; Calculate absorbance A₁(I^2–) and A₂(I^2–), wherein

2) sensitive membrane is immersed in the vessel accommodating buffered soln, buffered soln pH=5; First, second and third road light source provides stabilized light source to export, and calculates the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A2、I_B2、I_C2; Calculate absorbance A₁(HI^–) and A₂(HI^–), wherein

3) molar absorptivity ratio e is calculated₁、e₂、e₃, wherein e₁=A₁(HI^–)/A₂(HI^–), e₂=A₁(I^2–)/A₂(HI^–), e₃=A₂(I^2–)/A₂(HI^–). Can be calculated e₁=0.0507, e₂=1.501, e₃=0.3687.

4) sensitive membrane is immersed respectively in multiple vessel accommodating buffered soln, wherein buffered soln pH=6～11; Light source provides first, second and third road stabilized light source to export respectively, calculates the corresponding light intensity I of reference light paths that sensitive membrane is placed in each pH value buffered soln respectively_A0、I_B0、I_C0Light intensity I corresponding to optical path_A、I_B、I_C; Calculate and organize absorbance A more₁、A₂, whereinObtain the absorbance ratio R of sensitive membrane in different pH value buffered soln, R=A₁/A₂. At least measure 5 to 6 group absorbance ratios.

5) basisUtilize molar absorptivity ratio e₁、e₂、e₃With step 4) multiple absorbance ratio R of calculating prepare equation of linear regression: slope and the intercept obtaining equation of linear regression, as shown in Figure 3, wherein slope equals 1/n, and intercept equals pK_a. Can be calculated n=1/2.5441=0.393, pK_a=8.6116.

6) sensitive membrane being immersed in solution to be measured, light source provides first, second and third road stabilized light source to export, and calculates the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_AX、I_BX、I_CX; Calculate absorbance A_1XAnd A_2X, wherein

Calculate the absorbance A of water body to be measured_1X=0.1812, A_2X=0.2105, absorbance ratio R can be obtained_X=0.8608.

7) by n=0.393, pK_a=8.6116, e₁=0.0507, e₂=1.501, e₃=0.3687, R_X=0.8608 substitution formulaCan be calculated pH value of solution=8.193 to be measured. The accuracy of detection of pH value can reach 0.001.

A kind of structural representation that detect device based on sensitive membrane on-line checkingi water pH value detection method proposed by the invention for application shown in Figure 1, mainly comprises light source assembly, optical path component, signals collecting assembly, control unit and is provided with the sensitive membrane of pH sensitive agents. H in water body⁺Carry out reversible interaction with pH sensitive agents, the change of surface color occurs, thus causes the change of sensitive membrane absorbancy. When adopting the method and this device to calculate pH value based on pH sensitive membrane, the leakage of developer can not affect measuring result, accuracy of detection height, has the advantages such as reusable, volume is little, electromagnetism interference performance is strong and pollution-free.

Specifically, detect device to comprise the first enclosed housing 1 and the 2nd enclosed housing 2, first enclosed housing 1 and contact with external world's water body with the outer wall of the 2nd enclosed housing 2. Light source assembly 4 is arranged in the first enclosed housing 1, and for providing the stabilized light source of multiple wavelength to export, switch circuit 3 controls the switch of light source assembly 4. Optical path component comprises the spectral filter 5, condensing lens, opticcoupler 6, optical fiber 7 and the optical window that export corresponding setting with stabilized light source. Optical window comprises the first optical window 9 and the 2nd optical window 11, in the sidewall of the first optical window 9 and the 2nd optical window 11 difference corresponding embedding the first enclosed housing 1 and the 2nd enclosed housing 2, the first optical window 9 contacts with extraneous water body with the outside surface of the 2nd optical window 11.Condensing lens comprises the first condensing lens 8 and the 2nd condensing lens 12, first condensing lens 8 is arranged in the first enclosed housing 1, and the 2nd condensing lens 12 is arranged in the 2nd enclosed housing 2. The light that light source assembly sends is divided into two portions after spectral filter 5, opticcoupler 6, and a part, for measuring light, injects sensitive membrane 10 successively after the first condensing lens 8, first optical window 9, extraneous water body; Light through sensitive membrane 10 is penetrated to signals collecting assembly 13 successively after the 2nd optical window 11, the 2nd condensing lens 12; Another part, for ginseng is than light, is penetrated to signals collecting assembly 13 after optical fiber 7 conducts; Signals collecting assembly 13 is arranged in the 2nd enclosed housing 2, for carrying out opto-electronic conversion output detections signal to control unit 14. The detection signal that control unit 14 exports for Received signal strength acquisition component 13 and in the pH value of the extraneous water body of line computation. Signals collecting assembly 13 is photo-electric conversion element, comprises one or more in photorectifier, CCD or photomultiplier. Control unit 14 is micro-chip or the unicircuit that treater maybe can realize corresponding function.

The sensitive agents used in sensitive membrane 10 is the wherein one of phenol red, toluylene red, m-cresol purple or phenolphthalein, adopts sol-gel method to prepare sensitive membrane. The method preparing sensitive membrane 10 specifically comprises:

A, measures 2-10ml distilled water, 2-10ml dehydrated alcohol, the HCl of 1-5ml0.1M, 1-100mg sensitive agents, the tensio-active agent of 0-0.5ml and the tetraethoxy (TEOS) of 0-20ml, wherein tensio-active agent can be cationic, anionic or medium-sized wherein one. At room temperature stir to clarify after each composition is mixed.

B. aging 1 to 7 day of sol solutions step a obtained.

C. by spin coating method or soak stagnant crystal pulling method, utilize that step b obtains aging after solution prepare gel-film on the glass sheet; Before preparation, carry out glass sheet surface cleaning activation.

D. the glassy membrane of cleaning, drying sol-gel coating, obtains sensitive membrane. Glassy membrane is arranged between the first enclosed housing 1 and the 2nd enclosed housing 2. Specifically, glassy membrane is fixed in one side or quartz, glass that the first optical window 9 or the 2nd optical window 11 contact with extraneous water body.

For determining measuring parameter, it is necessary to obtain the spectrum of the sensitive membrane 10 of preparation. Preparation sensitive membrane spectrum specifically comprises the following steps:

E. configuring pH value is the buffered soln of 5-12, utilizes glass pH meter correction buffer solution;

F., the cuvette that the glassy membrane that sol-gel applies is placed in buffered soln respectively that accommodate different pH value, utilizes spectrophotometer or spectrograph to measure, obtains the sensitive membrane spectrum of sensitive membrane under different pH condition;

G. alkali state maximum absorption wavelength λ is obtained according to sensitive membrane spectrum₁With acid-state maximum absorption wavelength λ₂。

As shown in Figure 1, light source assembly comprises three illuminating sources 41,42,43 to provide first, second and third road stabilized light source output respectively. Illuminating source can be respectively LED, laser and halogen lamp. First via stabilized light source exports and the 2nd road stabilized light source exports as measurement light source, and the 3rd road stabilized light source exports as ginseng compares light source. The wavelength that first via stabilized light source exports and λ₁Close or equal, the wavelength that the 2nd road stabilized light source exports and λ₂Close or equal, the wavelength that the 3rd road stabilized light source exports is completely close or equal without the wavelength absorbed with sensitive membrane. Corresponding, spectral filter comprises the first spike filter 51, the 2nd spike filter 52 and the 3rd spike filter 53, wherein the centre wavelength of the first spike filter 51 and λ₁Close or equal, the centre wavelength of the 2nd spike filter 52 and λ₂Close or equal, the centre wavelength of the 3rd spike filter 53 is close or equal with the centre wavelength of the 3rd road stabilized light source.

When pH value is lower, [I^2–]+[HI^–]≈[HI^–]; When pH value is higher, [I^2–]+[HI^–]≈[I^2–]. When therefore measuring, first detection device is immersed in the vessel accommodating buffered soln, buffered soln pH=12. Three illuminating sources 41,42,43 provide stabilized light source to export, and signals collecting assembly 13 acquisition testing signal exports control unit 14 to, and control unit 14 calculates the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A1、I_B1、I_C1; Calculate absorbance A₁(I^2–) and A₂(I^2–), wherein

Then detection device is immersed in the vessel accommodating buffered soln, buffered soln pH=5; Light source assembly provides first, second and third road stabilized light source to export, and signals collecting assembly 13 acquisition testing signal exports control unit 14 to, and described control unit 14 calculates the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A2、I_B2、I_C2; Calculate absorbance A₁(HI^–) and A₂(HI^–), wherein

Control unit 14 calculates molar absorptivity ratio e₁、e₂、e₃, wherein e₁=A₁(HI^–)/A₂(HI^–), e₂=A₁(I^2–)/A₂(HI^–), e₃=A₂(I^2–)/A₂(HI^–)。

Calculate absorbance ratio R. Detection device is entered in multiple vessel accommodating buffered soln respectively. PH=6～11 of buffered soln. Light source assembly provides first, second and third road stabilized light source to export respectively, and signals collecting assembly 13 acquisition testing signal exports control unit 14 to. Control unit 14 calculates the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A、I_B、I_C; Calculate absorbance A₁、A₂, whereinObtain the many group absorbance ratio R of sensitive membrane 10 in different pH value buffered soln, R=A₁/A₂. It is good for obtaining 5 to 6 group data, it is also possible to obtain more multi-group data according to actual needs.

Control unit 14 is according to formula (6) and molar absorptivity ratio e₁、e₂、e₃The multiple absorbance ratio R calculated with step 4 prepare equation of linear regression. By e₁、e₂、e₃And multiple absorbance ratio substitutes into formula (6) one by one and prepares regression curve, obtain equation of linear regression L. It is 1/n that control unit 14 calculates the slope of regression equation, and intercept is pK_a。

After obtaining all measuring parameters, according to formulaDuring detection, the pH value in extraneous water body is only relevant with the absorbance ratio R of sensitive membrane in water body to be measured. Being immersed by detection device in solution to be measured, light source assembly provides first, second and third road stabilized light source to export, and signals collecting assembly 13 acquisition testing signal exports control unit 14 to, and control unit 14 calculates the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_AX、I_BX、I_CX; Calculate absorbance A_1XAnd A_2X, obtain the absorbance ratio R under current condition_X, wherein According to e₁、e₂、e₃With slope 1/n, intercept pK_a, control unit 14 can in line computation and export the pH value of solution to be measured, wherein

The detection method based on sensitive membrane on-line checkingi water pH value that above-described embodiment proposes and detection device, based on sensitive membrane technology, without the need to injecting added regent, device integrated level height, volume is little, energy consumption is low, it is convenient to carry, can reuse, there is accuracy of detection height, advantage that level of automation is high. The detection method proposed, measures pH value and absorbancy in the pH value range with indicator discoloration at water body linear. The pH value of detection only depends on this single parameter of absorbance ratio R, and chromogenic agent can not affect detected value, it is possible to effectively avoid indicator to leak the baseline wander caused.

Last it is noted that above embodiment is only in order to illustrate the technical scheme of the present invention, it is not intended to limit; Although with reference to previous embodiment to invention has been detailed description, it will be understood by those within the art that: the technical scheme described in foregoing embodiments still can be modified by it, or wherein part technology feature is carried out equivalent replacement;And these amendments or replacement, do not make the spirit and scope of the essence disengaging various embodiments of the present invention technical scheme of appropriate technical solution.

Claims (10)

1. the method based on sensitive membrane on-line checkingi water pH value, it is characterised in that, comprise the following steps:

1) sensitive membrane is prepared;

2) the different buffered soln of pH value is configured, by step 1) sensitive membrane prepared is placed in buffered soln, measure and obtaining step 1) absorption spectrum of sensitive membrane prepared, and the alkali state maximum absorption wavelength λ of sensitive membrane is obtained according to the absorption spectrum of described sensitive membrane₁With acid-state maximum absorption wavelength λ₂, obtain wavelength X₁And λ₂Time respectively corresponding absorbance A₁、A₂;

3) as buffered soln pH=11-13, step 2) absorbance A that obtains₁、A₂It is designated as A respectively₁(I^2-)、A₂(I^2-);

As buffered soln pH=4-6, step 2) absorbance A that obtains₁、A₂It is designated as A respectively₁(HI^-)、A₂(HI^-);

Utilize formula

e₁=ε₁(HI^–)/ε₂(HI^–)=A₁(HI^–)/A₂(HI^–),

e₂=ε₁(I^2–)/ε₂(HI^–)=A₁(I^2–)/A₂(HI^–),

e₃=ε₂(I^2–)/ε₂(HI^–)=A₂(I^2–)/A₂(HI^–),

Obtain molar absorptivity ratio e₁、e₂、e₃;

4) by step 1) sensitive membrane prepared is placed in the buffered soln of pH=6-11 respectively, obtains many group absorbance ratio R, R=A₁/A₂;

5) basisUtilize step 3) the molar absorptivity ratio e that obtains₁、e₂、e₃With step 4) many groups absorbance ratio R of obtaining prepares linear regression curves, obtains the slope 1/n and intercept pK of linear regression curves_a;

6) by step 1) sensitive membrane that obtains immerses water body to be measured, obtains wavelength X₁And λ₂Time respectively corresponding absorbance A_1X、A_2X, obtain the absorbance ratio R under current condition_X, R_X=A_1X/A_2X;

7) by step 3) the molar absorptivity ratio e that obtains₁、e₂、e₃, step 5) and the slope 1/n that obtains and intercept pK_a, step 6) and the absorbance ratio R that obtains_XSubstitute into formulaObtain the pH value of water body to be measured.

2. the method based on sensitive membrane on-line checkingi water pH value according to claim 1, it is characterised in that:

Prepare sensitive membrane by sol-gel method, specifically comprise the following steps:

A. measure distilled water, dehydrated alcohol, HCl, tensio-active agent and tetraethoxy respectively, take pH sensitive agents, at room temperature stir to clarify after mixing;

B. aging 1 to 7 day of sol solutions step a obtained;

C. by spin coating method or soak stagnant crystal pulling method, utilize that step b obtains aging after solution prepare gel-film on the glass sheet; Before preparation, carry out glass sheet surface cleaning activation;

D. the glassy membrane of cleaning, drying sol-gel coating, obtains sensitive membrane.

3. the method based on sensitive membrane on-line checkingi water pH value according to claim 1, it is characterised in that, the absorption spectrum measuring sensitive membrane specifically comprises the following steps:

E. configuring pH value is the buffered soln of 5-12, and utilizes glass pH meter to correct;

F., the cuvette that the sensitive membrane of preparation is placed in buffered soln respectively that accommodate different pH value, utilizes spectrophotometer or spectrograph to measure, obtains the sensitive membrane spectrum of sensitive membrane under different pH condition;

G. the alkali state maximum absorption wavelength λ of the sensitive membrane of preparation is observed according to described sensitive membrane spectrum₁With acid-state maximum absorption wavelength λ₂。

4. the method based on sensitive membrane on-line checkingi water pH value according to claim 1, it is characterised in that, adopt described step 3) obtain measuring parameter time, specifically also comprise the following steps:

I. sensitive membrane being immersed in the vessel accommodating buffered soln, wherein preparing described sensitive membrane pH sensitive agents used is diprotic acid, buffered soln pH=12;Light source provides first, second and third road stabilized light source to export, the wavelength that wherein first via stabilized light source exports equals the alkali state maximum absorption wavelength of described sensitive membrane, the wavelength that 2nd road stabilized light source exports equals the acid-state maximum absorption wavelength of described sensitive membrane, and the wavelength that the 3rd road stabilized light source exports equals reference wavelength; Calculate the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A1、I_B1、I_C1; Calculate absorbance A₁(I^2–) and A₂(I^2–), wherein

Ii. sensitive membrane is immersed in the vessel accommodating buffered soln, buffered soln pH=5; Light source provides first, second and third road stabilized light source to export, the wavelength that first via stabilized light source exports equals the alkali state maximum absorption wavelength of described sensitive membrane, the wavelength that 2nd road stabilized light source exports equals the acid-state maximum absorption wavelength of described sensitive membrane, and the wavelength that the 3rd road stabilized light source exports equals reference wavelength; Calculate the corresponding light intensity I of reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A2、I_B2、I_C2; Calculate absorbance A₁(HI^–) and A₂(HI^–), wherein

Iii. molar absorptivity ratio e is calculated₁、e₂、e₃, wherein e₁=A₁(HI^–)/A₂(HI^–), e₂=A₁(I^2–)/A₂(HI^–), e₃=A₂(I^2–)/A₂(HI^–);

Iv. absorbance ratio R is obtained; Sensitive membrane is immersed respectively in multiple vessel accommodating buffered soln, wherein buffered soln pH=6～11; Light source provides first, second and third road stabilized light source to export respectively, the wavelength that first via stabilized light source exports equals the alkali state maximum absorption wavelength of described sensitive membrane, the wavelength that 2nd road stabilized light source exports equals the acid-state maximum absorption wavelength of described sensitive membrane, and the wavelength that the 3rd road stabilized light source exports equals reference wavelength; Calculate many corresponding light intensity I of group reference light paths_A0、I_B0、I_C0Light intensity I corresponding to optical path_A、I_B、I_C; Calculate and organize absorbance A more₁、A₂, wherein Obtain the many group absorbance ratio R of sensitive membrane in different pH value buffered soln, R=A₁/A₂。

5. adopt the detection device based on sensitive membrane on-line checkingi water pH value method as described in item as arbitrary in Claims 1-4, comprise light source assembly, optical path component, signals collecting assembly and control unit; It is characterized in that, also comprise the first enclosed housing and the 2nd enclosed housing that contact with extraneous water body, and be provided with the sensitive membrane of pH sensitive agents; Wherein,

Described light source assembly is arranged in described first enclosed housing, for providing the stabilized light source of multiple wavelength to export;

Described optical path component comprises the spectral filter, condensing lens, opticcoupler, optical fiber and the optical window that export corresponding setting with described stabilized light source; Wherein, described optical window comprises the first optical window and the 2nd optical window, is embedded on the corresponding sidewall of the first enclosed housing and the 2nd enclosed housing respectively; Described condensing lens comprises the first condensing lens and the 2nd condensing lens, and described first condensing lens and the 2nd condensing lens are separately positioned in the first enclosed housing and the 2nd enclosed housing; The light that described light source assembly sends is divided into two portions after spectral filter, opticcoupler, and a part, for measuring light, injects sensitive membrane successively after the first condensing lens, the first optical window, extraneous water body; Light through described sensitive membrane is penetrated to signals collecting assembly successively after the 2nd optical window, the 2nd condensing lens; Another part, for ginseng is than light, is penetrated to signals collecting assembly after fiber optic conduction;

Described signals collecting assembly is arranged in described 2nd enclosed housing, for carry out opto-electronic conversion and output detections signal to control unit;

Described control unit be used for detection signal that Received signal strength acquisition component exports and in the pH value of the extraneous water body of line computation.

6. detection device according to claim 5, it is characterised in that, described sensitive membrane is arranged between the first enclosed housing and the 2nd enclosed housing and is fixed on described first optical window, the 2nd optical window, quartz or glass.

7. detection device according to claim 6, it is characterized in that, the wavelength that the first via stabilized light source that described light source assembly provides exports equals the alkali state maximum absorption wavelength of described sensitive membrane, the wavelength that 2nd road stabilized light source exports equals the acid-state maximum absorption wavelength of described sensitive membrane, and the wavelength that the 3rd road stabilized light source exports equals described sensitive membrane completely without the wavelength absorbed.

8. detection device according to claim 7, it is characterised in that, described spectral filter comprises first spike filter corresponding with light source assembly, the 2nd spike filter and the 3rd spike filter; The centre wavelength of wherein said first spike filter equals alkali state maximum absorption wavelength, and the centre wavelength of the 2nd spike filter equals acid-state maximum absorption wavelength, and the centre wavelength of the 3rd spike filter equals the centre wavelength of the 3rd road stabilized light source.

9. detection device according to claim 8, it is characterised in that, described signals collecting assembly comprises photorectifier, CCD and/or photomultiplier; Described light source assembly comprises the independent LED, laser and/or the halogen lamp that arrange.

10. detection device according to the arbitrary item of claim 5 to 9, it is characterised in that, described pH sensitive agents is phenol red, toluylene red, m-cresol purple or phenolphthalein.