Determination method for generation potential of carbon-containing disinfection by-product in amino acid chlorination process

Abstract

The invention discloses a method for determining the generation potential of a carbon-containing disinfection by-product in an amino acid chlorination process, and belongs to the field of water body detection. The determination method comprises the following steps: S1, taking amino acid as TOC to form a sample solution, and adjusting the pH value of the sample solution; s2, chlorine is added, and the chlorine adding amount and the culture time are determined; s3, measuring the concentration of carbon-containing disinfection byproducts in the sample solution, wherein the carbon-containing disinfection byproducts comprise halogenated acetaldehyde and halogenated ketone; and S4, determining the concentration of the carbon-containing disinfection by-product / the concentration of the amino acid, wherein the obtained result is the generation potential of the corresponding carbon-containing disinfection by-product. By determining the chlorine dosage calculation formula of the chlorination reaction in the determination mode of the generation potential of the carbon-containing disinfection by-products, the generation potential of various carbon-containing disinfection by-products in the free amino acid chlorination process can be accurately evaluated, and the repeatability and reliability of the determination result are convenient for data comparison and verification among different laboratories.

Description

Technical Field

[0001] The present invention belongs to the field of water body detection, and particularly relates to a method for determining the formation potential of carbonaceous disinfection by-products during the chlorination of amino acids. Background Art

[0002] With the increasing social concern about drinking water safety, significant progress has been made in the research on water disinfection by-products (DBPs). Currently, more than 700 disinfection by-products have been identified, among which trihalomethanes (THMs) and haloacetic acids (HAAs) are the main carbonaceous disinfection by-products (C-DBPs) in drinking water. These substances have received extensive attention due to their cytotoxicity, genotoxicity, and carcinogenicity. However, recent studies have found that some novel disinfection by-products, such as haloacetaldehydes (HALs) and haloketones (HKs), may pose a far greater potential hazard to human health than THMs and HAAs. These novel disinfection by-products have higher cytotoxicity and genotoxicity and are the key driving factors for cytotoxicity in drinking water.

[0003] Free amino acids are the key precursors for the formation of these carbonaceous disinfection by-products (C-DBPs). In source water, the concentration of free amino acids is usually 1 / 10 of that of combined amino acids, with an average concentration of about 406 nmol / L (about 52 μg / L). Although its concentration is lower than that of combined amino acids, studies have shown that free amino acids have a higher molar yield of disinfection by-products during chlorination. Therefore, it is particularly urgent to develop effective methods to control the formation of disinfection by-products during the chlorination of free amino acids.

[0004] The control of C-DBPs formation during the chlorination of free amino acids can be divided into three ways: (1) Source control: controlling the content of free amino acids or precursors of C-DBPs in the source water before disinfection to avoid the generation of C-DBPs from the source; (2) Process control: adjusting the water disinfection process to reduce the formation amount of C-DBPs; (3) End control: directly removing the formed C-DBPs after disinfection. In source control, conventional processes are difficult to effectively remove free amino acids in the source water, and the removal rate is only 40%. In process control, due to the complex and different formation mechanisms of C-DBPs, it is difficult for water plants to find a suitable disinfection process to comprehensively control the formation of C-DBPs. In end control, once C-DBPs are formed, they are difficult to remove, and since the precursors of C-DBPs still exist, even if the water plant has removed the C-DBPs in the water after disinfection, it is very likely that C-DBPs will be generated again under certain subsequent suitable conditions. Therefore, removing the precursors of DBPs in water to the greatest extent possible is the relatively most effective method, and the formation potential (FP) of C-DBPs is usually used to characterize the content level of such precursors.

[0005] Currently, the measurement methods for the formation potential (FP) of C-DBPs are continuously optimized, such as optimizing the chlorine dosage, disinfection time, and combined factors of pH-temperature, etc., to improve the accuracy of FP testing. However, the research on the optimal FP testing models for various C-DBPs during the chlorination of free amino acids is still in the development stage. Future research needs to further explore the influence of different factors on FP and develop more accurate and efficient FP testing models to better evaluate and control the formation of C-DBPs during the chlorination of free amino acids. Summary of the Invention

[0006] To solve the above technical problems, the present invention provides a method for measuring the formation potential of carbon-containing disinfection by-products during the chlorination of amino acids. This measurement method has high precision, good repeatability, and is convenient for comparison and verification.

[0007] The technical solution of the present invention is as follows:

[0008] The present invention provides a method for measuring the formation potential of carbon-containing disinfection by-products during the chlorination of amino acids, including the following steps:

[0009] S1: Using amino acids as TOC, forming a sample solution, and adjusting the pH value of the sample solution;

[0010] S2: Adding chlorine to determine the chlorine dosage and incubation time;

[0011] S3: Measuring the concentration of carbon-containing disinfection by-products in the sample solution, and the carbon-containing disinfection by-products include haloacetaldehydes and haloketones;

[0012] S4: Dividing the measured concentration of the carbon-containing disinfection by-products by the concentration of the amino acids, and the obtained result is the corresponding formation potential of the carbon-containing disinfection by-products;

[0013] Among them, the chlorine dosage calculation formula for the formation potential of haloacetaldehydes during the measurement is: Cl (mM) = X × M, where X can be any one of 8, 10, 16, 30, and M is the molar mass of the amino acid;

[0014] When measuring the formation potential of haloketones,

[0015] When the number of carbon atoms in the amino acid is less than 4, the chlorine dosage calculation formula for the chlorination reaction is: Cl (mM) = X × M, where X can be any one of 8, 10, 16, 30, and M is the molar mass of the amino acid;

[0016] When the number of carbon atoms in the amino acid is greater than or equal to 4, the chlorine dosage calculation formula for the chlorination reaction is: the residual chlorine remains at 1 ± 0.2 mg / L after 24 hours of the chlorination reaction.

[0017] Further, in the method for measuring the formation potential of haloacetaldehyde, the chlorine dosage calculation formula for the chlorination reaction is: Cl (mM) = 15 × M, where M is the molar mass of the amino acid.

[0018] Further, the amino acid is aspartic acid, alanine, glycine or serine.

[0019] Further, when the precursor is sufficient and the mass ratio of chlorine to the amino acid is less than 4:1, the formation potential of haloacetaldehyde increases with the increase of chlorine dosage;

[0020] When the precursor is insufficient and the mass ratio of chlorine to the amino acid is less than or equal to 1:1, the formation potential of haloacetaldehyde increases with the increase of chlorine dosage;

[0021] When the precursor is insufficient and the mass ratio of chlorine to the amino acid is greater than 1:1, as the chlorine dosage increases, the formation potential of haloacetaldehyde does not increase.

[0022] Further, when the amino acid is alanine, glycine or serine, the chlorine dosage calculation formula for the chlorination reaction to measure the formation potential of haloketone is: Cl (mM) = X × M, where X can be any number among 8, 10, 16, 30, and M is the molar mass of the amino acid; when the amino acid is aspartic acid, the chlorine dosage calculation formula for the chlorination reaction to measure the formation potential of haloketone is: the residual chlorine after 24 h of the chlorination reaction remains at 1 ± 0.2 mg / L.

[0023] Further, use 10 mM phosphate buffer solution to adjust the pH value of the sample solution so that the pH value of the sample solution is 7.

[0024] Further, the incubation time in step S2 is 24 hours, and it is necessary to incubate in the dark during the incubation process.

[0025] Further, the sample solution also includes phosphate buffer solution, bromide and iodide. The concentration of the phosphate buffer solution is 10 mM, the concentration of the bromide is 200 μg / L, the concentration of the iodide is 20 μg / L, the concentration of the amino acid is 10 mg / L, and the chlorination reaction of the sample solution is carried out in a brown glass bottle.

[0026] Further, measuring the concentration of carbonaceous disinfection by-products in the sample solution in step S3 includes the following steps:

[0027] S31: Based on the chlorine dosage calculation formula in the measurement method of the formation potential of various carbonaceous disinfection by-products, after determining the chlorine dosage, carry out the chlorination reaction;

[0028] S32: After the reaction ends, quench the residual chlorine in the solution with ascorbic acid at a molar residual chlorine concentration of 120% to terminate the continuous reaction;

[0029] S33: Use the method of liquid-liquid extraction to obtain an extract containing carbonaceous disinfection by-products;

[0030] S4 Analyze the extract by GC-MS method.

[0031] Further, the method of liquid-liquid extraction includes:

[0032] Acidify the quenched sample with concentrated sulfuric acid, then add sodium sulfate and methyl tert-butyl ether, let it stand after the reaction, and collect the organic layer;

[0033] Repeat the liquid-liquid extraction process again to obtain the extract;

[0034] Remove the moisture from the extract through a column containing sodium sulfate, concentrate it under nitrogen, and transfer it to a gas chromatography vial.

[0035] The beneficial technical effects of the present invention are:

[0036] The present invention discloses a method for determining the formation potential of carbonaceous disinfection by-products during the chlorination of amino acids. By measuring the formation potential (FP) of various carbonaceous disinfection by-products (such as haloacetaldehydes HALs, haloketones HKs, etc.) during the chlorination of free amino acids, it is possible to accurately evaluate the risk of generating C-DBPs during the chlorination of different amino acids. This method provides a scientific basis for the control of disinfection by-products in the water treatment process. The present invention improves the accuracy of FP testing by optimizing the chlorine dosage, improves the repeatability and reliability of the measurement results, and facilitates data comparison and verification between different laboratories. Through the method for determining the formation potential of carbonaceous disinfection by-products during the chlorination of amino acids of the present invention, it is possible to provide clear guidance for the optimization of chlorine dosage in the actual water treatment process, help reduce the generation of C-DBPs, effectively reduce the content of these harmful substances in drinking water, and thus improve the safety of water quality. Description of the Drawings

[0037] Figure 1 is a flowchart of the method for determining the formation potential of carbonaceous disinfection by-products in line with the present invention;

[0038] Figure 2 is a bar chart of the formation potential of carbonaceous disinfection by-products under the best model in line with the present invention. Detailed Embodiments

[0039] In order to better understand the technical means of the present invention and implement it in accordance with the content of the specification, the following further describes in detail the specific implementation manners of the present invention in combination with the accompanying drawings and embodiments. The following embodiments are used to illustrate the present invention but not to limit the scope of the present invention.

[0040] Please refer to Figure 1 as shown, the present invention provides a method for determining the formation potential of carbon-containing disinfection by-products during the chlorination of amino acids, and calculates the formation potential of carbon-containing disinfection by-products under the optimal model during the chlorination of different amino acids according to the Figure 1 determination method shown, as shown in Figure 2 .

[0041] Please continue to refer to Figure 1 and Figure 2 as shown, a method for determining the formation potential of carbon-containing disinfection by-products during the chlorination of amino acids includes the following steps:

[0042] S1: Use amino acids as TOC to form a sample solution and adjust the pH value of the sample solution. The amino acids are aspartic acid (Asp), alanine (Ala), glycine (Gly), or serine (Ser). Use 10 mM phosphate buffer to adjust the pH value of the sample solution so that the pH value of the sample solution is 7. The sample solution also includes phosphate buffer, bromide, and iodide. The concentration of the phosphate buffer is 10 mM, the concentration of the bromide is 200 μg / L, the concentration of the iodide is 20 μg / L, and the concentration of the amino acids is 10 mg / L.

[0043] S2: Add chlorine and determine the chlorine dosage and incubation time. Optionally, the incubation time is 24 hours, and during the incubation process, it is necessary to incubate in the dark. Therefore, the chlorination reaction of the sample solution is carried out in a brown glass bottle.

[0044] S3: Measure the concentration of carbon-containing disinfection by-products in the sample solution. The carbon-containing disinfection by-products include haloacetaldehydes (HALs) and haloketones (HKs);

[0045] Furthermore, measuring the concentration of carbon-containing disinfection by-products in the sample solution in step S3 includes the following steps:

[0046] S31: Based on the chlorine dosage calculation formula for the chlorination reaction in the determination method of the formation potential of various carbon-containing disinfection by-products, after determining the chlorine dosage, carry out the chlorination reaction;

[0047] S32: After the reaction ends, quench the residual chlorine in the solution with ascorbic acid with a 120% molar residual chlorine concentration to terminate the continuous reaction;

[0048] S33: Use the method of liquid-liquid extraction to obtain an extract containing carbonaceous disinfection by-products.

[0049] Further, the method of liquid-liquid extraction includes:

[0050] Acidify the quenched sample with concentrated sulfuric acid, then add sodium sulfate and methyl tert-butyl ether, let it stand after reaction, and collect the organic layer;

[0051] Repeat the liquid-liquid extraction process again to obtain an extract;

[0052] Remove moisture from the extract through a column containing sodium sulfate, concentrate it under nitrogen, and transfer it to a gas chromatography vial.

[0053] S34: Analyze the extract by GC-MS method. Further, for GC-MS instrument analysis, an Agilent 7890 gas chromatograph - 5977 mass spectrometer and an HP-5MS column are used for internal standard quantification.

[0054] S4: Divide the measured concentration of the carbonaceous disinfection by-product by the concentration of the amino acid, and the resulting value is the formation potential of the corresponding carbonaceous disinfection by-product.

[0055] Among them, the calculation formula for the chlorine dosage in the chlorination reaction in the measurement method of the formation potential of haloacetaldehydes (HALs) is: Cl (mM) = X × M, where X is any one of 8, 10, 16, 30, and M is the molar mass of the amino acid. Preferably, X = 15.

[0056] When measuring the formation potential of haloketones (HKs), when the number of carbon atoms in the amino acid is less than 4, the calculation formula for the chlorine dosage in the chlorination reaction is: Cl (mM) = X × M, where X can be any one of 8, 10, 16, 30, and M is the molar mass of the amino acid. For example, when the amino acid is alanine, glycine, or serine, the calculation formula for the chlorine dosage in the chlorination reaction for measuring the formation potential of haloketones is: Cl (mM) = X × M, where X can be any one of 8, 10, 16, 30, and M is the molar mass of the amino acid.

[0057] When the number of carbon atoms in the amino acid is greater than or equal to 4, the calculation formula for the chlorine dosage in the chlorination reaction is: the residual chlorine after 24 hours of chlorination reaction remains at 1 ± 0.2 mg / L. For example, when the amino acid is aspartic acid, the calculation formula for the chlorine dosage in the chlorination reaction for measuring the formation potential of haloketones is: the residual chlorine after 24 hours of chlorination reaction remains at 1 ± 0.2 mg / L.

[0058] The present invention can accurately evaluate the formation potential of various carbonaceous disinfection by-products during the chlorination of free amino acids by determining the chlorine dosage calculation formula for the chlorination reaction in the measurement method of the formation potential of carbonaceous disinfection by-products. Moreover, the repeatability and reliability of the measurement results facilitate data comparison and verification between different laboratories. Through a method for measuring the formation potential of carbonaceous disinfection by-products during the chlorination of amino acids according to the present invention, it can provide clear guidance for optimizing the chlorine dosage in the actual water treatment process, contribute to reducing the formation of C-DBPs, effectively reduce the content of these harmful substances in drinking water, and thus improve the safety of water quality.

[0059] Example 1

[0060] For haloacetaldehydes (HALs), the chlorine dosage calculation formula in its optimal FP measurement method is Cl (mM) = X × M, where X is any one of 8, 10, 16, 30, and M is the molar mass of the amino acid. Further, in Example 1, the chlorine dosage is Cl (mM) = 15 × M, where M is the molar mass of the amino acid.

[0061] Specifically, prepare four sample solutions, and add one amino acid to each sample solution.

[0062] Take a 125 mL brown glass bottle, add 10 mM phosphate buffer (pH = 7), 200 μg / L bromide, 20 μg / L iodide, and 10 mg / L amino acid as TOC and chlorine into the bottle. Incubate in the dark in an incubator at 25 °C for 24 h.

[0063] Quench the residual chlorine: After the reaction, quench the residual chlorine in the solution with ascorbic acid at 120% molar residual chlorine concentration to terminate the continuous reaction.

[0064] Liquid-liquid extraction: In a 125 mL brown bottle, acidify 100 mL of the quenched sample with concentrated sulfuric acid (pH < 1). Then add 15 g of sodium sulfate and 8 mL of methyl tert-butyl ether (MTBE), shake by hand for 1 minute, and let stand for 1 minute. Collect the organic layer and transfer it into a 20 ml glass test tube. Repeat the liquid-liquid extraction procedure again. The obtained extract is passed through a column containing 3 g of sodium sulfate to remove moisture, concentrated to 200 μL under nitrogen, and transferred to a 2 ml gas chromatography vial. Add 10 μL of 1,2-dibromopropane internal standard (25 mg / L) for GC-MS instrument analysis.

[0065] Instrument analysis: The instrument analysis of the sample is carried out using an Agilent 7890 gas chromatography-5977 mass spectrometry combined instrument and an HP-5MS column for internal standard quantification.

[0066] The specific parameters are as follows: The chromatographic column is an HP-5ms chromatographic column, with a model of 30m x 0.25mm x 0.25μm. The carrier gas is ultra-high purity helium (purity greater than 99.999%), and the helium carrier gas is a constant flow rate (1.2 mL / min). The inlet temperature is 220°C. Injection method: Split injection is adopted, the injection volume is 1 μL, and the split ratio is 5:1. The temperature program is: maintain at an initial temperature of 35°C for 2 min, then increase the temperature to 100°C at a rate of 4°C / min and hold for 2 min, then increase the temperature to 130°C at a rate of 9°C / min and hold for 1 min, and finally increase the temperature to 220°C at a rate of 12°C / min and hold for 1 min. The ion source temperature and quadrupole temperature are 230°C and 150°C respectively, and the electron energy is 70 eV. Sample analysis is carried out in the selected ion monitoring (SIM) mode.

[0067] The formation potential (FP) of haloacetaldehydes in the four amino acids is shown in Table 1.

[0068] Table 1 Formation potential (FP) of haloacetaldehydes (HALs) (μg / mg)

[0069]

[0070] It can be seen from Table 1 that when the chlorine dosage is Cl (mM) = 15 × M, where M is the molar mass of the amino acid. The formation potentials of haloacetaldehydes in the four amino acids are 12.98 μg / mg, 19.05 μg / mg, 2.1 μg / mg, and 2.39 μg / mg respectively. That is, during the chlorination process, aspartic acid (Asp) mainly produces TCAL (9.97 μg / mg) and BDCAL (1.5 μg / mg). This indicates that aspartic acid is one of the important precursors of haloacetaldehydes (HALs) during the chlorination process. The formation potential of alanine (Ala) is the highest, reaching 19.05 μg / mg, and mainly produces BDCAL (9.63 μg / mg) and TCAL (3.85 μg / mg). This shows that alanine is the main precursor of haloacetaldehydes during the chlorination process, and its formation potential is significantly higher than that of other amino acids. The formation potential is 2.1 μg / mg, mainly producing BDCAL (1.08 μg / mg) and TCAL (0.32 μg / mg). The formation potential of glycine is relatively low, but it can still produce a certain amount of haloacetaldehydes, mainly producing BDCAL (0.98 μg / mg) and BAL (0.82 μg / mg). The formation potential of serine is also relatively low, but the types produced are relatively diverse.

[0071] From the data in Table 1, it can be seen that there are significant differences in the formation potential of haloacetaldehydes (HALs) generated by different amino acids during chlorination. Alanine (Ala) and aspartic acid (Asp) are the main precursors of haloacetaldehydes, with relatively high formation potential. The formation potential of glycine (Gly) and serine (Ser) is relatively low, but they can still generate a certain amount of haloacetaldehydes. Therefore, during the drinking water disinfection process, special attention needs to be paid to the concentrations of alanine and aspartic acid to effectively control the formation of haloacetaldehydes and reduce the impact of disinfection by-products on water quality.

[0072] Comparative Examples 1-4

[0073] The chlorine dosages in Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4 were respectively Cl (mg / L) = 3×DOC + 8×NH3–N + 10, Cl (mM) = 10×M, Cl (mg / L) = 3×DOC, and the residual chlorine remained at 1 mg / L after 24 h of chlorination reaction. Among them, M is the molar mass of the amino acid. Other steps were carried out for experiments and detections according to the method of Example 1, and the results are shown in Table 2.

[0074] Table 2 Formation potential of haloacetaldehydes (μg / mg) of typical amino acids under different chlorine dosages

[0075]

[0076] As can be seen from Table 2, for Asp, the total formation potential of haloacetaldehydes (HALs) under different chlorine dosages (the sum of 7 HANs) was 13.0 μg / mg, 13.0 μg / mg, 10.8 μg / mg, 7.2 μg / mg, and 13.0 μg / mg respectively. It can be seen that the formation of haloacetaldehydes (HALs) by Asp during chlorination is determined by the amount of chlorine used (chlorine dosage).

[0077] When the precursor is sufficient and the mass ratio of chlorine to the amino acid is less than 4:1, the formation potential of the haloacetaldehyde increases with the increase of chlorine dosage.

[0078] When the precursor is insufficient and the mass ratio of chlorine to the amino acid is less than or equal to 1:1, the formation potential of the haloacetaldehyde increases with the increase of chlorine dosage.

[0079] When the precursor is insufficient and the mass ratio of chlorine to the amino acid is greater than 1:1, as the chlorine dosage increases, the formation potential of the haloacetaldehyde does not increase. This means that the precursor has been completely converted into haloacetaldehyde. At this time, the organic precursor is the limiting factor for the formation potential of haloacetaldehyde.

[0080] For Ala, the total HALs generation potential under different chlorine dosages (sum of 7 HANs) is 7.1 μg / mg, 11.4 μg / mg, 6.9 μg / mg, 4.7 μg / mg and 19.1 μg / mg, respectively. That is, the HALs generation potential under the chlorine dosage in Example 1 is the highest, indicating that the chlorine dosage may have reached the optimal condition at this time, maximizing the HALs generation potential of Ala.

[0081] Furthermore, the chlorine dosages were 40.0 mg / L, 80.0 mg / L, 30.0 mg / L, 23.0 mg / L and 120 mg / L, respectively, indicating that the HALs formation of Ala was also determined by the chlorine dosage and was in good agreement with the chlorine dosage. In other words, the HALs formation potential of Ala was also determined by the chlorine dosage and was highly correlated with the chlorine dosage.

[0082] For Ser, the total potential of halogenated acetaldehydes (HALs) under different chlorine dosages (the sum of 7 HANs) is 0.6 μg / mg, 0.4 μg / mg, 0.9 μg / mg, 0.4 μg / mg and 2.4 μg / mg, respectively. It can be seen that the formation rules of Ser and Ala are the same and are also affected by the amount of chlorine.

[0083] For Gly, the total potential for the formation of halogenated acetaldehydes (HALs) under different chlorine dosages (the sum of 7 HANs) is 0.1 μg / mg, 0.7 μg / mg, 2.7 μg / mg, 0.1 μg / mg and 2.1 μg / mg, respectively. The chlorine dosages of Comparative Examples 1-4 and Example 1 are 40.0 mg / L, 95.0 mg / L, 30.0 mg / L, 66.0 mg / L and 142 mg / L, respectively. The results show that Gly is a special free amino acid. When the mass ratio of chlorine to Gly is less than 4:1, Gly hardly forms halogenated acetaldehyde. When the mass ratio of chlorine to glycine is greater than 6.6:1, as the amount of chlorine increases, the formation of halogenated acetaldehyde first decreases and then increases.

[0084] As can be seen from the above, the halogenated acetaldehyde generation potential of Asp, Ala and Ser is mainly determined by the chlorine dosage and is highly correlated with the chlorine dosage. Gly shows a particularity, and its halogenated acetaldehyde generation potential shows a trend of first decreasing and then increasing under a specific chlorine dosage.

[0085] Therefore, the best formation potential determination method for halogenated acetonitrile is: the chlorine dosage calculation formula is Cl (mM) = X × M, wherein X is any number among 8, 10, 16, 30, and M is the molar mass of the amino acid.

[0086] Example 2

[0087] For halogenated ketones (HKs), when the number of carbon atoms in the amino acid is greater than or equal to 4, the calculation formula for the chlorine dosage in the chlorination reaction is: the residual chlorine remains at 1 ± 0.2 mg / L after 24 hours of chlorination reaction. For example, aspartic acid. When the number of carbon atoms in the amino acid is less than 4, the calculation formula for the chlorine dosage in the chlorination reaction is: Cl (mM) = X × M, where X can be any one of 8, 10, 16, 30, and M is the molar mass of the amino acid. For example, alanine, glycine, or serine.

[0088] The chlorine dosage of each amino acid is carried out in the following five ways:

[0089] (1) Cl (mg / L) = 3 × DOC + 8 × NH3–N + 10;

[0090] (2) Cl (mM) = 10 × M, where M is the molar mass of the amino acid;

[0091] (3) Cl (mM) = 15 × M, where M is the molar mass of the amino acid;

[0092] (4) Cl (mg / L) = 3 × DOC

[0093] (5) The residual chlorine remains at 1 ± 0.2 mg / L after 24 hours of chlorination reaction. Where M is the molar mass of the amino acid.

[0094] Other steps are carried out for experiments and detections according to the method of Example 1, and the results are shown in Table 3.

[0095] Table 3 Formation potential (FP) (μg / mg) of halogenated ketones (HKs) under different chlorine dosages

[0096]

[0097] As can be seen from Table 3, for aspartic acid (Asp), in chlorine dosage methods (1) and (2): the formation potential is 0.4 μg / mg for both, indicating that these two methods have little effect on the formation of halogenated ketones of Asp. The formation potentials of chlorine dosage methods (3) and (4) are 0.6 μg / mg and 0.9 μg / mg respectively, indicating that increasing the chlorine dosage can improve the formation of halogenated ketones of Asp. The formation potential of chlorine dosage method (5) is 1.1 μg / mg, indicating that chlorine dosage method (5) can significantly improve the formation potential of halogenated ketones of Asp. Therefore, when the amino acid is aspartic acid, the calculation formula for the chlorine dosage in the chlorination reaction for determining the formation potential of halogenated ketones is: the residual chlorine remains at 1 ± 0.2 mg / L after 24 hours of chlorination reaction.

[0098] For alanine (Ala), the formation potentials of chlorine dosing methods (1) and (2) are 0.3 μg / mg and 0.4 μg / mg respectively. The formation potentials of chlorine dosing methods (4) and (5) are 0.4 μg / mg and 0.3 μg / mg respectively. The formation potential of chlorine dosing method (3) is 0.9 μg / mg, indicating that the formation of halo ketones from Ala can be increased under this chlorine dosing condition. Therefore, when the amino acid is alanine, the chlorine dose calculation formula for the chlorination reaction to determine the formation potential of halo ketones is: Cl (mM) = 15×M, where X can be any one of 8, 10, 16, 30, and M is the molar mass of the amino acid.

[0099] For glycine (Gly), chlorine dosing methods (1) and (2): the formation potentials are 0.02 μg / mg and 0.2 μg / mg respectively, indicating that increasing the chlorine dosage can improve the formation of halo ketones from Gly. Chlorine dosing methods (4) and (5): the formation potentials are both 0 μg / mg, indicating that these two methods have no effect on the formation of halo ketones from Gly. The formation potential of chlorine dosing method (3) is 0.4 μg / mg, indicating that the formation of halo ketones from Gly can be significantly increased under this chlorine dosing method. Therefore, when the amino acid is glycine, the chlorine dose calculation formula for the chlorination reaction to determine the formation potential of halo ketones is: Cl (mM) = 15×M, where X can be any one of 8, 10, 16, 30, and M is the molar mass of the amino acid.

[0100] For serine (Ser), chlorine dosing methods (1) and (2): the formation potentials are 0.03 μg / mg and 0.2 μg / mg respectively, indicating that increasing the chlorine dosage can improve the formation of halo ketones from Ser. Chlorine dosing methods (4) and (5): the formation potentials are 0 μg / mg and 0.01 μg / mg respectively, indicating that these two methods have little effect on the formation of halo ketones from Ser. The formation potential of chlorine dosing method (3) is 0.4 μg / mg, indicating that the formation of halo ketones from Ser can be significantly increased under this chlorine dosing method. Therefore, when the amino acid is serine, the chlorine dose calculation formula for the chlorination reaction to determine the formation potential of halo ketones is: Cl (mM) = 15×M, where X can be any one of 8, 10, 16, 30, and M is the molar mass of the amino acid.

[0101] Example 3

[0102] In Example 3, the chlorine dosage was such that the residual chlorine remained at 1 ± 0.2 mg / L after 24 h of chlorination reaction. Other steps were carried out for experiments and detections according to the method of Example 1. The results of the formation potentials of halo ketones formed from different amino acids are shown in Table 4.

[0103] Table 4 Formation potential (FP) of halo ketones (HKs) (μg / mg)

[0104]

[0105] As can be seen from Table 4, under the current chlorination conditions, aspartic acid (Asp) is the main precursor for the formation of haloacetones. The formation potential of haloacetones (HKs) during chlorination mainly focuses on CP (chloroacetone), with a formation potential of 0.96 μg / mg, accounting for the vast majority of the total formation potential, approximately 90.6%. This indicates that when the chlorine dosage is appropriate, aspartic acid is sufficient to undergo partial chlorination reactions but not sufficient to form a large amount of other haloacetones. The formation potential of haloacetones generated from other amino acids is relatively low, indicating that their contribution to haloacetones under the current chlorination conditions is small.

[0106] Example 5

[0107] In Example 5, the calculation formula for the chlorine dosage of the chlorination reaction for determining the formation potential of haloacetones is: Cl (mM) = X × M, where X can be any number among 8, 10, 16, and 30, and M is the molar mass of the amino acid. Other steps are carried out for experiments and detections according to the method of Example 1. The results of the formation potential of haloacetones generated from different amino acids are shown in Table 5.

[0108] Table 5 Formation potential (FP) of haloacetones (HKs) (μg / mg)

[0109]

[0110]

[0111] By comparing Table 4 and Table 5, it can be seen that under the chlorine dosage conditions of Example 5, the formation potential of haloacetones from aspartic acid is relatively low. For other amino acids under these chlorine dosage conditions, the formation potential of haloacetones is relatively high. Moreover, 1,1,1-TCP (1,1,1-trichloroacetone) is the main haloacetone formed during the chlorination of all amino acids, and its formation potential accounts for the vast majority of the total formation potential.

[0112] In summary, for the method for determining the formation potential of carbonaceous disinfection by-products during the chlorination of amino acids in the present invention, by determining the calculation formula for the chlorine dosage of the chlorination reaction in the method for determining the formation potential of carbonaceous disinfection by-products, the formation potential of various carbonaceous disinfection by-products during the chlorination of free amino acids can be accurately evaluated. Moreover, the repeatability and reliability of the measurement results facilitate data comparison and verification between different laboratories. Through the method for determining the formation potential of carbonaceous disinfection by-products during the chlorination of amino acids in the present invention, it can provide clear guidance for the optimization of chlorine dosage in the actual water treatment process, contribute to reducing the formation of C-DBPs, effectively reduce the content of these harmful substances in drinking water, and thus improve the safety of water quality.

[0113] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process, characterized in that: The following steps are involved: S1: Using amino acids as TOC to form a sample solution and adjusting the pH value of the sample solution; S2: adding chlorine, determining the chlorine dosage and incubation time; S3: determining the concentration of carbon-containing disinfection byproducts in the sample solution, wherein the carbon-containing disinfection byproducts include halogenated acetaldehydes and halogenated ketones; S4: measuring the concentration of the carbon-containing disinfection by-product / the concentration of the amino acid, and the result obtained is the corresponding carbon-containing disinfection by-product generation potential; The calculation formula of the chlorine dosage of the chlorination reaction in the determination method of the formation potential of haloacetaldehyde is: Cl (mM) = X × M, where X can be any number among 8, 10, 16, and 30, and M is the molar mass of the amino acid; When determining the formation potential of haloketones, When the number of carbon atoms in the amino acid is less than 4, the chlorine dosage calculation formula for the chlorination reaction is: Cl (mM) = X × M, where X can be any number among 8, 10, 16, and 30, and M is the molar mass of the amino acid; When the number of carbon atoms in the amino acid is greater than or equal to 4, the chlorine dosage calculation formula for the chlorination reaction is: the residual chlorine remains at 1±0.2 mg / L after 24 hours of chlorination reaction.

2. The method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process according to claim 1, characterized in that: The calculation formula of the chlorine dosage of the chlorination reaction in the determination method of the formation potential of haloacetaldehyde is: Cl (mM) = 15 × M, wherein M is the molar mass of the amino acid.

3. The method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process according to claim 1, characterized in that: The amino acid is aspartic acid, alanine, glycine or serine.

4. The method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process according to claim 1, characterized in that: When the precursor is sufficient and the mass ratio of chlorine to the amino acid is less than 4:1, the generation potential of the haloacetaldehyde increases with the increase of the chlorine dosage; When the precursor is insufficient and the mass ratio of chlorine to the amino acid is less than or equal to 1:1, the generation potential of the haloacetaldehyde increases with the increase of the chlorine dosage; When the precursor is insufficient and the mass ratio of chlorine to the amino acid is greater than 1:1, the chlorine dosage is increased without increasing the potential for generating the haloacetaldehyde.

5. The method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process according to claim 1, characterized in that: When the amino acid is alanine, glycine or serine, the chlorine dosage calculation formula for the chlorination reaction for determining the potential for the formation of halogenated ketones is: Cl (mM) = X × M, wherein X can be any number among 8, 10, 16, 30, and M is the molar mass of the amino acid; when the amino acid is aspartic acid, the chlorine dosage calculation formula for the chlorination reaction for determining the potential for the formation of halogenated ketones is: the residual chlorine is maintained at 1 ± 0.2 mg / L after 24 hours of chlorination reaction.

6. The method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process according to claim 1, characterized in that: The pH value of the sample solution was adjusted to 7 using 10 mM phosphate buffer.

7. The method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process according to claim 1, characterized in that: The culture time in step S2 is 24 hours, and the culture needs to be incubated in the dark.

8. The method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process according to claim 1, characterized in that: The sample solution also includes phosphate buffer, bromide and iodide, the concentration of the phosphate buffer is 10mM, the concentration of the bromide is 200μg / L, the concentration of the iodide is 20μg / L, the concentration of the amino acid is 10mg / L, and the chlorination reaction of the sample solution is carried out in a brown glass bottle.

9. The method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process according to claim 1, characterized in that: Determining the concentration of carbon-containing disinfection byproducts in the sample solution in step S3 comprises the following steps: S31: Based on the chlorine dosage calculation formula of the chlorination reaction in the determination method of the concentration generation potential of various carbon-containing disinfection by-products, after determining the chlorine dosage, the chlorination reaction is carried out; S32: After the reaction is completed, ascorbic acid with a molar residual chlorine concentration of 120% is used to quench the residual chlorine in the solution to terminate the reaction; S33: using a liquid-liquid extraction method to obtain an extract of carbon-containing disinfection by-products; S34: Analyze the extract using GC-MS method.

10. The method for determining the potential for formation of carbon-containing disinfection by-products in the amino acid chlorination process according to claim 9, characterized in that: The liquid-liquid extraction method comprises: The quenched sample was acidified with concentrated sulfuric acid, and then sodium sulfate and methyl tert-butyl ether were added. After the reaction, the sample was allowed to stand and the organic layer was collected. Repeat the liquid-liquid extraction process again to obtain an extract; The extract was passed through a column containing sodium sulfate to remove moisture, concentrated to 50 Å under nitrogen, and transferred to a gas chromatography bottle.

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