A method for measuring the light reflectivity of the inner wall of an ultraviolet reactor by compound degradation

Abstract

The invention belongs to the field of environmental engineering water treatment, and specifically relates to a method for measuring the light reflectance of the inner wall of an ultraviolet light reactor by compound degradation. The method mainly comprises: a 254nm ultraviolet lamp tube and a stainless steel light reactor. By adopting this method, the light reflectance of the inner wall of the light reactor can be simply and quickly measured, providing guidance for the design and optimization of ultraviolet advanced oxidation process reactors in engineering applications.

Description

Technical Field

[0001] The invention belongs to the field of environmental engineering water treatment, and in particular relates to a method for measuring the light reflectivity of the inner wall of an ultraviolet light reactor through compound degradation. Background Art

[0002] Ultraviolet disinfection technology is one of the most widely used disinfection processes in water treatment processes. It has the advantages of high disinfection efficiency, good spectral characteristics, small footprint, safety and reliability. Advanced oxidation processes based on ultraviolet have also received widespread attention in the study of drinking water treatment of organic matter. The threat of organic micropollutants such as pharmaceutical pollutants, odor substances, endocrine disruptors, disinfection by-products, algae toxins to drinking water quality has been widely recognized. These organic micropollutants not only have a serious impact on water ecology, but also seriously endanger human health. It has been reported that organic micropollutants in drinking water can increase people's risk of cancer, the probability of newborn malformations, and accelerate the spread of drug-resistant bacteria. Conventional water treatment technologies (including coagulation and sedimentation, filtration adsorption, oxidation disinfection and other methods) are difficult to efficiently degrade organic micropollutants in water. Advanced oxidation processes based on ultraviolet have received widespread attention because they can effectively remove organic micropollutants in water. It is one of the new trends in the development of drinking water treatment technology.

[0003] At present, energy saving and consumption reduction are the development direction of the world. How to obtain higher disinfection or treatment effects with the same energy input is an important field of UV-based water treatment technology. In terms of engineering applications, UV reactors are generally designed as stainless steel cylinders to ensure that as much light as possible is absorbed by the reaction system. At present, the design and optimization of UV reactors mainly rely on computational models. However. Currently, few models take into account the reflection of the inner wall of the UV reactor, and the research on the determination of the light reflectivity (loss rate) of its inner wall through experiments is very limited, which limits the further optimization of the energy consumption of the UV reactor. .

[0004] In summary, there is an urgent need for a simple and efficient method to measure the light reflectivity of the inner wall of a UV reactor. Summary of the invention

[0005] The purpose of the present invention is to provide a method for obtaining the light reflectance of the inner wall of an ultraviolet reactor by measuring the degradation of a compound, to provide a method with high accuracy and simple operation for measuring the light reflectance of the inner wall of an ultraviolet reactor in engineering applications, and to provide a reference for the design and optimization of the ultraviolet reactor.

[0006] The first technical solution proposed by the present invention to solve the technical problems in the prior art is to provide a method for measuring the light reflectance of the inner wall of a UV reactor by compound degradation, comprising the following steps:

[0007] 1. The formula for calculating the light reflectivity of the inner wall of the UV reactor is derived:

[0008] Assuming that the light reflectivity of the inner wall of the UV reactor is a constant, set as η, then the light intensity after each reflection can be expressed as:

[0009] I i+1 =η·I′ i (1)

[0010] Then the total absorbance of the reaction system I a It can be expressed as:

[0011]

[0012] In the buffer solution system prepared with ultrapure water, the background absorbance of water quality can be ignored, so I a That is, the effective light intensity of the reaction system (I 有效 ). Set the inner diameter of the reactor to D, and assume that the change in the total light absorption of the system is negligible. According to the Lambert-Beer law, the light absorption of the system after each reflection can be obtained:

[0013]

[0014] We take the logarithm of both sides of Formula 3 and combine it with Formula 1, we can find that I′ i (i≥1) is a geometric progression (Formula 5)

[0015]

[0016] Formula 2 can be simplified to:

[0017]

[0018] In summary, combining formulas 6 and 7, by measuring the effective light intensity of the system (that is, I a ) and the initial emission intensity of the lamp (I 0 ), the light reflectivity of the inner wall of the UV reactor can be measured.

[0019] 2. Effective light intensity (i.e. I a ) and the initial emission intensity of the lamp (I 0 )

[0020] 1) The initial emission intensity of the lamp (I 0 ) can be measured by light intensity meter or iron oxalate chemical indicator.

[0021] 2) Since the derivation of the formula in 1 is based on the premise that the change in the total absorbance of the system is negligible, a substance that can be directly photolyzed and whose absorbance change before and after the photolysis reaction is not large is selected as a standard compound, and the effective light intensity of the reaction system (that is, I a ):

[0022] 3) The degradation rate (Rate) of the standard compound in the UV reactor can be expressed as:

[0023]

[0024] In engineering applications, UV reactors are generally designed as cylindrical shapes with highly reflective surfaces to ensure that as much light as possible is absorbed by the reaction system. Since light is constantly reflected, it is generally believed that the optical path of the UV reactor is large enough, so Formula 8 can be simplified to:

[0025]

[0026] Since the present invention is carried out in a buffer system configured with ultrapure water, the background absorbance of the water quality is A b can be ignored, so Formula 9 can be simplified to:

[0027] Rate=I a ·Φ (10)

[0028] In summary, I a and I 0 By substituting formula 6 and 7, the light reflectivity of the inner wall of the UV reactor can be measured.

[0029] Beneficial effects:

[0030] The beneficial effects of the present invention are:

[0031] 1) The present invention proposes a method for measuring the light reflectance of the inner wall of an ultraviolet light reactor by compound degradation, which provides a method with high accuracy and simple operation for measuring the light reflectance of the inner wall of an ultraviolet light reactor in engineering applications, and provides a reference for the design and optimization of ultraviolet reactors. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of light reflection of stainless steel UV reactor. DETAILED DESCRIPTION

[0033] The present invention is further described below by specific examples and drawings. The examples of the present invention are intended to enable those skilled in the art to better understand the present invention, and do not limit the present invention in any way.

[0034] Example 1

[0035] This example uses the commonly used disinfectant chloramine (NH 2 Cl) as a standard compound, the reaction time is shorter to ensure that NH 2 The concentration of Cl before and after the reaction does not change much. The light reflectivity of the inner wall of the UV reactor is measured. The specific steps are as follows:

[0036] 1) Prepare 1 mM NH 2 Cl stock solution is ready for use;

[0037] 2) Use a beaker to prepare 500 ml of 10 μM NH 2 Cl solution, and the pH of the reaction solution was controlled at 7.0 using 5 mM phosphate buffer solution;

[0038] 3) Place the reaction solution in a stainless steel UV reactor and react for 5 min. 254 NH 2 Cl is degraded, and the reaction is carried out at room temperature;

[0039] 4) Take samples at the reactor outlet and use the DPD method to measure NH 2 The concentration of NH 2 The degradation rate of NH Cl was obtained by consulting the literature. 2 Cl in UV 254 The quantum yield is 0.291 mol·E -1 , substituting into formula (10) to obtain I a 2.85×10 -6 Einstein L -1 ·s -1 ;

[0040] (5) Obtain NH by consulting the literature 2 The molar absorption coefficient of Cl is 382M -1 cm -1 ;

[0041] (6) I was measured by experiment 0 8.60×10 -6 Einstein L -1 .s -1 ;

[0042] (7) The inner diameter D of the UV reactor is 4.6 cm.

[0043] Substituting the above values ​​into Formulas 6 and 7, we obtain that the light reflectivity of the inner wall of the ultraviolet light reactor used in this experiment is 40%.

[0044] It should be understood that the embodiments and examples discussed here are for illustrative purposes only and may be modified or altered by those skilled in the art, and all such modifications and alterations should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for measuring the light reflectivity of the inner wall of an ultraviolet light reactor by compound degradation, mainly comprising the following steps: deriving a formula for calculating the light reflectivity of the ultraviolet light reactor: Assuming that the light reflectivity of the inner wall of the UV reactor is a constant, set as η, then the light intensity after each reflection can be expressed as I i+1 =η·I′ i (1) Then the effective light intensity of the reaction system is a It can be expressed as: I ɑ =(I0-I′0)+(I1-I′1)+(I2-I′2)+...+(I n -I′ n ) =I0-(I′0-I1)-(I′1-I2)-(I′2-I3)-...-(I′ n-1 -I n )-I′ n =I0-(I′0-η I′0)-(I′1-η I′1)-(I′2-η I′2)-...-(I′ n-1 -η I′ n )-AND' n =I0-(1-η)·(I′0+I′1+I′2+...+I′ n-1 )-I′ n (2) In the buffer solution system prepared with ultrapure water, the background absorbance of water quality can be ignored, so I a That is, the effective light intensity of the reaction system. The inner diameter of the reactor is set to D. Assuming that the change in the total light absorption of the system is negligible, according to the Lambert-Beer law, the light absorption of the system after each reflection can be obtained: We take the logarithm of both sides of formula (3) and combine it with formula (1), we can find that I′ i (i≥1) is a geometric progression, as shown in formula (5): Formula (2) can be simplified as: Combining formulas (6) and (7), the effective light intensity I of the reaction system is determined a And the initial emission light intensity I0 of the lamp tube, the light reflectivity of the inner wall of the ultraviolet reactor can be measured.

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