Water treatment agent sodium acetate content field rapid detection reagent, preparation method and detection method

Abstract

The application discloses a water treatment agent sodium acetate content field rapid detection reagent, a preparation method and a detection method. The reagent comprises a chromogenic agent, and the chromogenic agent is a water solution of ferrous chloride and hydrochloric acid, wherein the volume ratio of ferrous chloride to hydrochloric acid is 50:1. The detection method comprises the following steps: step 1, moving the water treatment agent sodium acetate content field rapid detection reagent to a transparent glass test tube with a threaded plug to prepare a ready-to-use sodium acetate visual detection reagent bottle; step 2, taking the sodium acetate visual detection reagent bottle in step 1, adding a water treatment agent sodium acetate sample into the bottle, mixing uniformly, and comparing with a standard colorimetric card to obtain the content of the water treatment sodium acetate sample. The application can determine the result by visual comparison after the reaction is completed (only 1 minute is needed), and the whole process from sample treatment to conclusion takes no more than 5 minutes, the detection efficiency is improved by 6 times, and the application is especially suitable for field rapid screening scenes.

Description

Technical Field

[0001] This invention relates to the field of water quality testing technology, and in particular to a rapid on-site detection reagent, preparation method, and detection method for sodium acetate content in water treatment agents. Background Technology

[0002] Sodium acetate is currently the most common and widely used external carbon source in wastewater treatment plants. However, the quality of the products varies greatly, with many substandard products being produced using waste acid as raw material. Testing for the content of industrial-grade sodium acetate is mostly conducted in laboratories. Relevant standard testing methods include the industry standard HG / T5959-2021 "Sodium Acetate as a Carbon Source for Biochemical Treatment of Wastewater" and the group standard T / CASMES20-2022 "Industrial Sodium Acetate". HG / T5959-2021 uses acid-base titration, and the presence of other acids can affect the test results. T / CASMES20-2022 uses potentiometric titration, and improper handling of the perchloric acid used in this method may cause an explosion.

[0003] Other detection methods for sodium acetate include spectrophotometry, conductivity methods, ion chromatography, and high-performance liquid chromatography. National Patent CN114152692A discloses a method for simultaneously determining industrial-grade sodium acetate and citric acid using ion chromatography, revealing that the detection method separates sodium acetate and citric acid using an ion chromatograph, thus achieving simultaneous detection of both. National Patent CN113340834A discloses a rapid method for determining the sodium acetate content in an industrial-grade sodium acetate solution, revealing that the detection method uses ultraviolet-visible spectrophotometry to detect the content of industrial-grade sodium acetate. National Patent CN119224069A discloses a rapid method for determining the sodium acetate content in an industrial-grade sodium acetate solution, revealing that the detection method uses the conductivity of a sodium acetate standard solution to plot a working curve, and then detects the content in the actual sample. National Patent CN118671226A discloses a method for detecting the acetate content in sodium nitroprusside using high performance liquid chromatography. The method reveals that the retention time of sodium nitroprusside and acetate is separated by gradient elution, thereby achieving accurate determination of the acetate content in sodium nitroprusside.

[0004] All of these testing methods require bringing samples of the sodium acetate water treatment agent back to a specialized laboratory for analysis by professional technicians. Most methods also require expensive, large-scale precision instruments, and the results can be delayed by hours or even days. However, the dosage of sodium acetate is directly related to water treatment effectiveness and production costs. If its content cannot be controlled in a timely manner, it will not only lead to a passive and delayed adjustment of the wastewater treatment process, but may also cause fluctuations in treatment effectiveness due to dosage imbalances, significantly increasing operating costs.

[0005] Therefore, it is necessary to provide a reagent and method for determining the sodium acetate content in water treatment agents that is easy to operate and can be used for rapid on-site detection. Summary of the Invention

[0006] This invention aims to solve the problems of the inability to quickly detect the content of sodium acetate in water treatment agents on-site and the cumbersome testing procedures, and provides a reagent, preparation method and detection method for rapid on-site detection of sodium acetate content in water treatment agents.

[0007] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: A rapid on-site detection reagent for sodium acetate content in water treatment agents includes a colorimetric reagent, wherein the colorimetric reagent is an aqueous solution of ferrous chloride and hydrochloric acid, and the volume ratio of ferrous chloride to hydrochloric acid is 50:1.

[0008] Furthermore, the ferrous chloride used is analytical grade ferrous chloride tetrahydrate, and the hydrochloric acid used is atomic fluorescence grade hydrochloric acid.

[0009] Preferably, the concentration of ferrous chloride tetrahydrate is 200 g / L, and the volume ratio of hydrochloric acid in the system is 2%. Under this specific acidic environment, the highly specific reaction between ferrous ions and sodium acetate is achieved. The synergistic effect of the above parameters ensures the stability of the reaction color and the resistance to interference.

[0010] The present invention also provides a rapid on-site detection reagent for the sodium acetate content of a water treatment agent as described in claim 1, comprising the following steps: Weigh out a certain amount of ferrous chloride tetrahydrate, pure water, and hydrochloric acid, mix them evenly, let stand overnight, and filter the supernatant into a glass reagent bottle for storage after it turns bright green.

[0011] This invention also provides a method for rapid on-site detection of sodium acetate content in water treatment agents, comprising the following steps: Step 1: Transfer the sodium acetate content rapid on-site test reagent for water treatment agent into a transparent glass test tube with a screw-stopper to make a ready-to-use sodium acetate visual test reagent bottle; Step 2: Take the sodium acetate visual test reagent bottle from Step 1, add the sodium acetate sample (water treatment agent), mix well, and compare with the standard colorimetric card to obtain the content of the sodium acetate sample to be tested.

[0012] Furthermore, the preparation method of the standard colorimetric card in step 2 is as follows: Step 21: Prepare analytical grade sodium acetate standard solutions with mass fractions of 17%, 18%, 19%, 20%, and 21%; Step 22: Take 6 sodium acetate visual test reagent bottles and add 0 mL, 0.90 mL of 17% sodium acetate, 0.90 mL of 18% sodium acetate, 0.90 mL of 19% sodium acetate, 0.90 mL of 20% sodium acetate, and 0.90 mL of 21% sodium acetate respectively. Mix well, and the colors will sequentially appear as bright green, bright green, yellow-green, light brown, orange-brown, and reddish-brown. Step 23: Take color photos and use drawing tools to create a standard color chart.

[0013] Furthermore, in step 2, the amount of sodium acetate sample added as a water treatment agent is 0.90 mL.

[0014] Furthermore, before testing the sodium acetate content of the water treatment agent, a preliminary judgment of the sodium acetate sample content needs to be made: transfer 0.90 mL of 20% sodium acetate standard solution and the sodium acetate sample of the water treatment agent to two sodium acetate visual test reagent bottles, mix well, and compare the colors of the two reagent bottles. If the reddish-brown color of the sodium acetate sample of the water treatment agent is lighter than the reddish-brown color of the 20% sodium acetate standard solution, then the sample content is less than 20%.

[0015] Specifically, the detection principle of this invention is based on the heterogeneous colorimetric reaction between ferrous ions (Fe²⁺) and sodium acetate (CH₃COONa) under specific conditions, enabling rapid detection of sodium acetate content in water treatment agent samples. The core reaction mechanism is as follows: In an acidic system, sodium acetate undergoes a complexation reaction with ferrous ions to form a reddish-brown soluble complex. The color depth of this complex is positively correlated with the sodium acetate concentration; that is, the higher the sodium acetate content, the darker the color of the reaction system, and vice versa. Qualitative identification and quantitative analysis of sodium acetate can be achieved through visual colorimetry.

[0016] The present invention has the following beneficial effects: 1. Detection efficiency is greatly improved, enabling "instant detection". Among the existing mainstream detection methods, titration requires manual control of the titration speed and observation of the endpoint, which is cumbersome and takes about 30 minutes per test; ion chromatography requires sample dilution pretreatment, instrument preheating, column equilibration and other processes, and usually takes more than 30 minutes per test.

[0017] This invention utilizes the intuitiveness of color reaction, allowing for visual comparison to determine the result after the reaction is complete (in just 1 minute). The entire process from sample processing to conclusion takes no more than 5 minutes, improving detection efficiency by 6 times, making it particularly suitable for rapid on-site screening scenarios.

[0018] 2. Strong anti-interference ability and higher detection specificity Existing titration methods (such as acid-base titration) are easily affected by other acidic / basic substances in the sample, leading to results that are too high or too low. In this invention, the complexation reaction between ferrous ions and acetate ions is highly specific. Under certain pH conditions, common anions (such as Cl⁻, SO4²⁻, NO3⁻) and organic substances such as sugars and proteins do not participate in the reaction. It can be directly detected without additional purification steps, and its anti-interference ability is significantly better than that of traditional methods. 3. Low operating threshold, no professional technicians required. Existing instrumental analysis methods (such as chromatography) require operators to master professional skills such as instrument calibration, parameter setting, and spectral interpretation, and the instrument maintenance costs are high; titration methods are highly dependent on experience in endpoint judgment and are prone to result deviations due to human error.

[0019] The core operation of this invention consists of only three steps: "sample addition—reaction—colorimetry," which can be mastered without complex training. Using a pre-made standard colorimetric card (marked with color gradients corresponding to different concentrations), ordinary personnel can directly compare the differences between the sample and the standard color level, achieving "foolproof" operation and reducing reliance on professionals.

[0020] 4. The equipment cost is extremely low, making it suitable for grassroots promotion. The purchase cost of a single ion chromatograph is over 100,000 yuan, and it requires supporting laboratory facilities. This invention requires only basic equipment such as glass test tubes and pipettes (total cost less than 1,000 yuan), and does not require continuous investment in consumables (such as chromatographic columns and standard solutions), reducing equipment costs by more than 99%, making it especially suitable for low-cost demand scenarios.

[0021] 5. Wider range of applications, overcoming environmental limitations Existing instrumental analysis methods are limited by equipment size and power requirements, making them unsuitable for use outside the laboratory; titration methods require a stable operating table and are not suitable for on-site mobile testing. All operations of this invention can be completed at room temperature, and the core equipment is easy to carry and can be used directly in non-laboratory environments such as production workshops, thus solving the pain point of "laboratory constraints" of traditional methods. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process of the present invention; Figure 2 Standard colorimetric cards for visually detecting the reaction of sodium acetate solutions of different mass fractions with sodium acetate reagent. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] like Figure 1 The diagram shown is a schematic representation of the process of this invention.

[0026] Example 1 The effect of ferrous chloride concentration was investigated: Ferrous chloride (FeCl₂·4H₂O) solutions with mass concentrations of 20 g / L, 60 g / L, 100 g / L, 200 g / L, 300 g / L, and 400 g / L were prepared sequentially. During dissolution, hydrochloric acid was added at a volume fraction of 1% to inhibit the hydrolysis of ferrous chloride. The solutions initially appeared yellow and turbid. After standing overnight, the upper part of the solution turned bright green, and a small amount of red precipitate formed at the bottom. To prevent the precipitation from affecting the solution, filtration was performed after preparation. 10.00 mL of each of the above ferrous chloride solutions was accurately transferred to 15 mL transparent reagent bottles. Then, a 20% sodium acetate solution was added dropwise to each bottle while mixing, until the solution color just changed. The experimental phenomena showed that the solution color gradually deepened with increasing ferrous chloride concentration (see Table 1). Considering the distinguishability of the solution color, when the ferrous chloride concentration is 200 g / L, the solution color is significantly different from that of solutions of other concentrations, which can meet the observation requirements of subsequent experiments. Therefore, 200 g / L was selected as the experimental concentration of the ferrous chloride solution.

[0027] Table 1. Color changes of 20% sodium acetate reacting with different concentrations of rapid detection reagents. Example 2 The effect of acidity on ferrous chloride was investigated: A 200 g / L ferrous chloride (FeCl2·4H2O) solution was prepared. During the dissolution process, hydrochloric acid was added sequentially at volume fractions of 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, and 3.0% to prepare solutions with different acidities. 10.00 mL of each acidity solution was accurately transferred to a 15 mL transparent glass reagent bottle, and then a 20% sodium acetate solution was added dropwise to each bottle while mixing. As the acidity of ferrous chloride increased, the amount of 20% sodium acetate solution required for the ferrous chloride solution to change color also gradually increased (see Table 2). Considering the convenience of actual operation and reagent costs, the hydrochloric acid addition ratio was determined to be 2.0%.

[0028] Table 2. Amount required for the reaction of 20% sodium acetate with rapid detection reagents of different acidities. Example 3 The final preparation method for the sodium acetate visual detection reagent is as follows: Weigh 200.00g of ferrous chloride tetrahydrate into a 1000mL beaker, add about 900mL of pure water and 20.0mL of hydrochloric acid, stir thoroughly to dissolve, transfer to a 1000mL volumetric flask, dilute to the mark with pure water, mix well, let stand overnight, and after the supernatant turns bright green, filter into a glass reagent bottle for storage.

[0029] Preparation of sodium acetate visual test reagent bottle: Accurately transfer 10.00 mL of the above rapid test reagent into a 15 mL transparent glass bottle with a screw stopper, seal, and store in the dark until use.

[0030] Example 4 Preparation of sodium acetate standard colorimetric cards: Prepare analytical grade sodium acetate standard solutions with mass fractions of 17%, 18%, 19%, 20%, and 21%, respectively. Weigh 17.00 g, 18.00 g, 19.00 g, 20.00 g, and 21.00 g of analytical grade anhydrous sodium acetate, respectively, and dissolve them in 83.00 g, 82.00 g, 81.00 g, 80.00 g, and 79.00 g of pure water, respectively, and mix thoroughly. Take six sodium acetate visual test reagent bottles and add 0 mL, 0.90 mL of 17% sodium acetate, 0.90 mL of 18% sodium acetate, 0.90 mL of 19% sodium acetate, 0.90 mL of 20% sodium acetate, and 0.90 mL of 21% sodium acetate, respectively, and mix thoroughly. The colors will sequentially appear as bright green, bright green, yellowish green, light brown, orange-brown, and reddish-brown. Take color photographs and use WPS drawing tools to create the standard colorimetric cards as follows. Figure 2 When the sodium acetate content is below 17%, it appears bright green; when the sodium acetate content is between 17% and 18%, it appears yellowish-green; when the sodium acetate content is between 18.0% and 19.0%, it appears light brown; when the sodium acetate content is between 19% and 20%, it appears orange-brown; and when the sodium acetate content is above 20%, it appears reddish-brown.

[0031] Example 5 Determining the shelf life of the sodium acetate visual test reagent: Prepare the sodium acetate visual test reagent according to the steps above. After preparation, store it for 1 day, 3 days, 5 days, 10 days, 15 days, 25 days, 31 days, and 45 days respectively. Then, react the sodium acetate visual test reagent with 20% analytical grade sodium acetate standard solution with different shelf lives and compare the results with the standard colorimetric card. The reaction color of this rapid test reagent with sodium acetate after 3 to 31 days is basically consistent with the colorimetric card. The reagent stored for 45 days shows a darker color than the standard colorimetric card when used to test sodium acetate samples. Therefore, the ferrous chloride rapid test reagent can be stored and used for one month.

[0032] Example 6 A rapid on-site detection method for sodium acetate content in water treatment agents includes the following steps: Step 1: Preliminary judgment of sodium acetate content in water treatment agent sodium acetate sample: Take two sodium acetate visual test reagent bottles, add 0.90 mL of 20% sodium acetate standard solution and 0.90 mL of water treatment agent sodium acetate sample to each bottle respectively, mix well and compare the colors. If the color of the water treatment agent sodium acetate sample is lighter than that of the 20% sodium acetate standard solution, it indicates that the content of sodium acetate in the water treatment agent sample is less than 20%.

[0033] Step 2: Take one sodium acetate visual test reagent bottle, add 0.90 mL of sodium acetate sample for water treatment, mix well, and compare with the standard color chart. When comparing the color with the standard color chart, it should be observed under sufficient natural light or LED light, with white as the background to avoid interference from other colors. The content range of sodium acetate sample for water treatment is detected by the corresponding color of the color chart.

[0034] Example 7 To verify the accuracy of the sodium acetate visual detection reagent, eight sodium acetate samples from different batches of water treatment agents with varying sodium acetate contents were selected. Ion chromatography was used to detect the sample contents, which were 8.40%, 16.8%, 18.8%, 19.0%, 20.0%, 24.8%, 14.7%, and 18.4% respectively. Following the detection method of the sodium acetate visual detection reagent, the colors of the eight samples were, in order, bright green, bright green, light brown, light brown, orange-brown, reddish-brown, bright green, and yellow-green. The color identification results were consistent with the ion chromatography results, as shown in Table 3.

[0035] Table 3 Comparison of results for visual detection reagents and ion chromatography methods for detecting sodium acetate samples used as a water treatment agent. Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0036] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A rapid on-site detection reagent for sodium acetate content in water treatment agents, characterized in that, The reagent includes a colorimetric agent, which is an aqueous solution of ferrous chloride and hydrochloric acid, wherein the volume ratio of ferrous chloride to hydrochloric acid is 50:

1.

2. The rapid on-site detection reagent for sodium acetate content in water treatment agents according to claim 1, characterized in that, The ferrous chloride used is analytical grade ferrous chloride tetrahydrate, and the hydrochloric acid used is atomic fluorescence grade hydrochloric acid.

3. A method for preparing a rapid on-site detection reagent for sodium acetate content in a water treatment agent as described in claim 1, characterized in that, Includes the following steps: Weigh out a certain amount of ferrous chloride tetrahydrate, pure water, and hydrochloric acid, mix them evenly, let stand overnight, and filter the supernatant into a glass reagent bottle for storage after it turns bright green.

4. A rapid on-site detection method for sodium acetate content in water treatment agents, characterized in that, Includes the following steps: Step 1: Transfer the reagent described in any one of claims 1-2 into a transparent glass test tube with a threaded stopper to prepare a ready-to-use sodium acetate visual detection reagent bottle; Step 2: Take the sodium acetate visual test reagent bottle from Step 1, add the sodium acetate sample (water treatment agent), mix well, and compare with the standard colorimetric card to obtain the content of the sodium acetate sample to be tested.

5. The method for rapid on-site detection of sodium acetate content in a water treatment agent according to claim 4, characterized in that, The preparation method of the standard colorimetric card in step 2 is as follows: Step 21: Prepare analytical grade sodium acetate standard solutions with mass fractions of 17%, 18%, 19%, 20%, and 21%; Step 22: Take 6 sodium acetate visual test reagent bottles and add 0 mL, 0.90 mL of 17% sodium acetate, 0.90 mL of 18% sodium acetate, 0.90 mL of 19% sodium acetate, 0.90 mL of 20% sodium acetate, and 0.90 mL of 21% sodium acetate respectively. Mix well, and the colors will successively appear as bright green, bright green, yellow-green, light brown, orange-brown, and reddish-brown. Step 23: Take color photos and use drawing tools to create a standard color chart.

6. The method for rapid on-site detection of sodium acetate content in water treatment agents according to claim 4, characterized in that, In step 2, 0.90 mL of sodium acetate sample, a water treatment agent, was added.

7. The method for rapid on-site detection of sodium acetate content in a water treatment agent according to claim 4, characterized in that, Before testing the sodium acetate content of the water treatment agent, a preliminary judgment of the sodium acetate sample content is required: transfer 0.90 mL of 20% sodium acetate standard solution and the sodium acetate sample of the water treatment agent into two sodium acetate visual test reagent bottles, mix well, and compare the colors of the two reagent bottles. If the reddish-brown color of the sodium acetate sample of the water treatment agent is lighter than the reddish-brown color of the 20% sodium acetate standard solution, the sample content is less than 20%.

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