How to measure the chromaticity of sewage

Physical and chemical examination-PTCA (Part B: Chemistry. Anal. ) Volume 44, 2008

① Determination of wastewater chromaticity in work briefing Guo Yao, Wang Jianwei (Dongguan Municipal Wastewater Treatment Plant, Dongguan 523080) Abstract: As an improvement of the conventional method, spectrophotometry is proposed to determine wastewater chromaticity instead of visual colorimetry, and dilute sulfuric acid solution prepared with potassium dichromate and cobalt sulfate (acidity is about 0.02mol? L- 1) is used as the standard solution for measuring chromaticity. The absorption peak of this standard solution is 350nm, which is used as the wavelength determination standard and the absorbance of water samples. The standard curves with chromaticity between 10 and 100 were made, and the effects of temperature, turbidity and acidity of test solution were tested. The detection limit of this method is 5. Key words: spectrophotometry; Visual colorimetry; Chromaticity; China sewage map classification number: O657.3 1 document identification number: A document number:100124020 (2008) 012005438+0202 Determination of chromaticity of h2so 4 solution (about 0.02mol? L- 1) k 2 Cr 2 o 7 and so4assolution for preparation of standard cuve. The absorption is measured at a wavelength of 350 nm, which is the maximum absorption value of the standard solution. The alinearStandardCurve Covercolor Yb is prepared between 10 and 100. The factors affecting the determination (i.e. temperature, turbidity and acidity of water sample) were studied. detectionlimitofthismethodwasfoundtob 5。 Key words: spectrophotometry; Visual colorimetry; Color; The chromaticity of sewage is the basic control item of water quality monitoring in urban sewage treatment plants. There are two ways to determine the chromaticity of water. The chromaticity of clean natural water and drinking water is determined by platinum-cobalt standard colorimetry or chromium-cobalt standard colorimetry [1], and industrial sewage, surface water polluted by industrial sewage and domestic sewage are determined by dilution multiple method. Fresh domestic sewage contains a lot of organic matter, inorganic salts, suspended solids and colloidal substances, which makes the water turbid and light grayish brown. After domestic sewage is treated by sewage treatment plant or filtered by 0.45μm membrane, the water sample is clear, with low chroma and yellowish color, which can be determined by the above two methods. The dilution multiple method needs to dilute the water sample into different dilution multiples, and then compare it with optical pure water to finally determine the dilution multiple of the water sample. For domestic sewage not polluted by industrial wastewater and effluent treated by sewage treatment plant, there is little difference in chromaticity after 5 ~ 20 times dilution.

It is difficult to receive manuscripts. Date: 20062062 13 About the author: Guo Yao (1965-), female, from Guangzhou, engineer, mainly engaged in chemical analysis. Distinguish with your eyes. Standard colorimetry determines the chromaticity of water samples by preparing a series of chromaticity standard solutions and then comparing them with water samples visually. The same disadvantage of these two methods is that they are greatly influenced by the color, scale, weather and human factors of the colorimetric tube. The experimental results show that the Cr-Co standard solution has the maximum absorption peak near the wavelength of 350nm, and the absorbance and chromaticity conform to Lambert's law in the range of chromaticity 10 ~ 100. This method uses potassium dichromate instead of potassium chloroplatinate to prepare chromaticity standard solution, and uses spectrophotometer instead of human eyes for quantitative determination. 1 test part 1. 1 instruments and reagents carry 50 ultraviolet 2 visible spectrophotometer; Microporous water purifier, filtering membrane and suction and filtration device. 500 Cr-Co standard solution [1]: accurately weigh 0.0437g of potassium dichromate and cobalt sulfate (CoSO4? 7H2O) 1.000g is dissolved in a small amount of water, 0.5mL of concentrated sulfuric acid is added and diluted to 500mL with water. The chroma of this solution is 500. ? 16?

Physical and chemical inspection-chemical volume Guo Yao, etc.:

Drawing the standard curve of sewage chromaticity 1.2: Take 500 Cr-Co standard solution 0, 1, 2, 10 ml in a 50mL colorimetric tube, dilute it to scale with purified water, and shake it evenly. The chromaticity of each tube is 10, 20, 40, 60 respectively.

. Figure 1 chromaticity standard curve 1 chromaticity standard curve made of chromium (Ⅵ) 2 cobalt (Ⅱ) standard solution (chromaticity: 10- 100). The standard solution with the same chromaticity has the same color after dilution, and the standard solution of chromium and cobalt can be used instead of the standard solution of platinum and cobalt for determination. 2 results and discussion 2. 1 determination wavelength selection (1) Take platinum and cobalt standard solutions of 10 ~ 100 respectively, use purified water as a blank for baseline calibration, and scan 1cm cuvette in the wavelength range of 200~ 800262nm. There is almost no absorption at the wavelength less than 300nm, so the platinum-cobalt standard solution is not suitable for quantitative determination in the range of 10 ~ 100. The scanning spectrum is shown in Figure 2.

. Fig. 2 absorption spectrum of platinum-cobalt standard solution with chromaticity of 10 (absorption spectrum with chromaticity of 10 in fig. 2 and equivalent chromaticity of cobalt standard solution (2) respectively take chromium-cobalt standard solution with chromaticity of 10 ~ 100, and scan in the wavelength range of 200 ~ 800 357nm by the same operation steps.

. The chromaticity of fig. 3 is 10 (a), 20 (b), 40 (c) and 60 (d), and the absorption spectra are 80 (e) and 100 (f) chromium (ⅵ) 2 cobalt (Ⅱ) standard solution cobalt (Ⅱ)/kloc. 40 (c), 60 (d), 80 (e) and 100 (f) (3) respectively take raw water and treated water from the sewage treatment plant and scan them in the wavelength range of 200 ~ 800 nm, with the same operation steps; In the ultraviolet region at 257nm, because the organic matter and nitrate in the water sample interfere with the determination of chromaticity, 350nm, which is close to the visible region and has no interference, is selected as the determination wavelength, and the standard curve with chromaticity between 10 ~ 100 is made. The scanning spectrum is shown in Figure 4.

. Fig. 4 absorption spectra of water samples in the influent and effluent Fig. 4 absorption spectra of water samples 2.2 The influence of temperature, turbidity [1] and acidity [2] on chromaticity at room temperature can be ignored. Turbidity has a great influence on chromaticity, and the water sample can be removed after being filtered by 0.45μm membrane. Under the conditions of slight acidity and neutrality, the influence of acidity on chromaticity is very small and can be ignored. 2.3 detection limit [1] in spectrophotometry, the detection limit is the concentration corresponding to the absorbance of 0.0 1 after deducting the blank value. The detection limit of this method is 5. 2.4 Determination of water samples The water samples containing suspended solids and turbidity should be determined after being filtered by a 0.45μm filter membrane. 50 ml of pretreated water sample is divided into colorimetric tubes (or diluted appropriately), the absorbance is determined according to the steps of drawing standard curve, and the chromaticity of water sample is automatically calculated according to the standard curve instrument. (Continued from page 65)? 26?

Physical and chemical inspection-chemical volume Wang Yongxiang, etc. ：

Determination and quality evaluation of trace elements in wild litchi in Dabie Mountain Table 2 Recovery rate, precision test and comparison with ICP2AES method (n = 8) Table 2 Recovery rate, precision test and analysis. Results obtained bythissmethodandbycp2eaes element actual measurement Am 'toftheelementfound plus scalar Am' toffstdsadddρ/(mg? L- 1) total element discovery recovery rate recovery rate /% RSD /% ICP2AES method measurement results obtained bycp2aaes rho/(mg? L- 1

)mg 0. 180.200 . 40 1 10.00 . 170。

19ca 0 . 350 . 400 . 7292 . 5 1 . 140.37 Zn 0 . 4 10 . 400 . 8097 . 50 . 480 . 38 Cu 0 . 330 . 300 . 6565 1 . 340 . 29 Fe 5 . 25 . 29505305

Table 3 Comparison of Six Trace Elements in Li Tou, Soybean and Black Bean

Table 3 6 Comparison of contentoftheofthesoybean and blackbean of Trace 2 Elements Inchinesevelvetbean

The content of six elements found is w/(μ g? G- 1) Mg CaZnCuFeMn Li Dou 2532177767.0920.86112.945438+0.02 soybean+05.586538+08.85/kloc. Comparing the determination results of Li Dou, black beans and soybeans, it can be seen that the contents of magnesium, manganese and copper in Li Dou are obviously higher than those in other two similar crops, which has high development and utilization value. References: [1] Liu Ping, Wu Shide. Determination of copper, zinc, manganese, sodium and magnesium in fragrant rice and rice by atomic absorption spectrometry [J]. China Gong * * * Health Journal, 2002,23 (3): 5282528. [2], Du Zhu. Atomic absorption spectrometry and its application [j].11(4): 67271.[3] Yan Bing, Yang Jun, Zhou Jing. Determination of several nutrient elements in leaves of Malus auratus by flame atomic absorption spectrometry [J]. Journal of Natural Science, Harbin Normal University, 2003, 19(4):77280. [4] Wang Xiumin. Determination of potassium, sodium, calcium and magnesium in wheat seeds by atomic absorption spectrometry [J]. Journal of Hebei Agricultural University, 2003,26 (4): 90293. [5] Wang Ping, Zhang,. Black rice, black beans, black sesame seeds. 2( 1):952 98.[6] Meicun, Beigu, Yuangu. Counter2 icdedetection byicp2aesfordetermination finorga2o2 Icanion in Watersolution Oncology YusingWitterionics Status Arypase [J]. An Naijin,1998,70 (5): 9362942. [7] Donneger, Ege

A. Evaluation of digestion procedure for determination of trace elements by flame atomic absorption spectrometry [J]. Analchimata, 2004,520 (1/2): 2172222. [8] balasa Brahmanian, Pugalentif. Determination of Total Chromium in Wastewater by Inductively Coupled Plasma Atomic Emission Spectrometry [J]. Taranta,1999,50 (3): 4572

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(Continued from page 62) Raw water and treated water of domestic sewage from sewage treatment plant are respectively taken, and after pretreatment, they are determined according to the standard colorimetric method in the literature [1] and this method. See table 1 for the results.

. Table 1 Comparison Table of Chromaticity Results Measured by Visual Colorimetry and Spectrophotometry 1

Visual Colorimetry and Spectrophotometric Determination Colorimetric Basis of Chromaticity Value 20050403 Inlet 20050403 Outlet 2005003 Outlet 200507 Inlet 200507 Outlet 200507 Outlet 200507 Outlet 200507 Outlet Visual Colorimetry 15 ~ 20 10 About 655/kloc- Kloc-0/. 1 10.8 8.4 As can be seen from the table 1, the results obtained by the standard colorimetric method of chromium and cobalt are within a certain range, and the results obtained by this method are a certain value, and the results obtained by the two methods are consistent. The advantage of this method is that the standard curve is established in advance, and only the water sample is pretreated for each determination, and then the absorbance is determined, and the instrument automatically calculates the chromaticity of the water sample. The operation is simple, the result is accurate and the human error is reduced. References: [1] Editorial Committee of Monitoring and Analysis Methods for Water and Wastewater of State Environmental Protection Bureau. Monitoring and analysis methods of water and wastewater [M]. Fourth edition. Beijing: China Environment Press, 2002. [2] GB11903-1989 determination of water color [56?