Water quality sulfate detection reagent and preparation method thereof, water quality sulfate detection method

Abstract

The invention discloses a water quality sulfate detection reagent and a preparation method thereof, a water quality sulfate detection method, wherein the water quality sulfate detection reagent includes a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is a permanganate compound, the precipitant liquid includes a precipitant and a precipitation stabilizer, the precipitant is a soluble barium salt, the precipitation stabilizer includes an acid solution and a surfactant, the acid solution concentration in the precipitant liquid is 0~0.5mol / L, and the reducing agent is at least one of ascorbic acid, sodium ascorbate, and sodium thiosulfate. When the water quality sulfate detection reagent of the present invention is used for water sample detection, it can show significant advantages such as high sensitivity, good selectivity, wide measurement range and short test time, and is very suitable for on-site rapid determination of sulfate content in water samples under various application scenarios.

Description

Technical Field

[0001] The invention belongs to the technical field of water quality detection, and in particular relates to a water quality sulfate detection reagent and a preparation method thereof, and a water quality sulfate detection method. Background Art

[0002] Sulfate ion (SO4 2- ) is a common component in natural water bodies. When its concentration increases and enters the industrial water system, it will accelerate the corrosion of iron pipes and concrete structures, especially affecting the safety and life of infrastructure such as bridges and tunnels. In urban water supply systems, high concentrations of sulfate can cause scaling in water pipes, reduce water flow efficiency, increase maintenance costs and the frequency of pipe replacement, and impose a burden on municipal management. Although low concentrations of sulfate are harmless to the human body, sulfate in water exceeding 250 milligrams per liter (mg / L) may cause gastrointestinal discomfort or diarrhea, posing a health risk to sensitive groups such as infants and the elderly. Therefore, accurate and rapid determination of sulfate content in water is very important for environmental protection and public health monitoring.

[0003] At present, the widely used methods for determining sulfate are barium sulfate gravimetric method, barium sulfate turbidimetric method, and precision instrumental analysis method. The barium sulfate gravimetric method has high accuracy, but the operation is cumbersome, the test time is long, and it is not suitable for environmental field use. The barium sulfate turbidimetric method is difficult to quantify visually due to its white color and lack of color tone change. Precision instrumental analysis methods (such as ion chromatography, barium chromate photometry, and indirect atomic absorption spectrometry) are suitable for batch testing of low-content samples and can provide highly accurate results, but they usually require professional equipment and technicians and are not conducive to rapid on-site detection. In addition, Chinese patent CN109612987 A also discloses a method for preparing sulfate test paper, which is easy to use and suitable for preliminary screening; however, its sensitivity is low and the preparation process is relatively complicated, which limits its possibility of widespread application. In summary, although the existing sulfate detection methods perform well under laboratory conditions, they still face many challenges in practical applications, especially in scenarios requiring rapid response and portability.

[0004] Therefore, there is an urgent need for a water quality sulfate detection reagent and a preparation method thereof, and a water quality sulfate detection method to solve the deficiencies of the existing technical problems. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a water quality sulfate detection reagent and a preparation method thereof, and a water quality sulfate detection method. When the water quality sulfate detection reagent of the present invention is used for water sample detection, it can show significant advantages such as high sensitivity, good selectivity, wide measurement range (0~1000 mg / L) and short test time, and is very suitable for on-site rapid determination of sulfate content in water samples in various application scenarios.

[0006] To achieve the above objectives, the first aspect of the present invention provides a water quality sulfate detection reagent, comprising a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is a permanganate compound, the precipitant liquid comprises a precipitant and a precipitation stabilizer, the precipitant is a soluble barium salt, and the precipitation stabilizer comprises an acid solution and a surfactant; the acid solution concentration in the precipitant solution is 0~0.5mol / L, and the reducing agent is at least one of ascorbic acid, sodium ascorbate, and sodium thiosulfate.

[0007] Compared with the prior art, the water quality sulfate detection reagent of the present invention includes a colorant liquid, a precipitant liquid, and a reducing agent, wherein the colorant in the colorant liquid is an oxidizing and colored permanganate compound, and the precipitant is a soluble barium salt; when the water quality sulfate detection reagent contacts the water sample to be tested, the soluble barium salt reacts with the sulfate in the water sample to form an insoluble barium sulfate precipitate; during the formation of barium sulfate, the permanganate ions in the permanganate compound interact with the barium sulfate to form a red mixed crystal, which is very stable and will not disappear due to subsequent washing or the action of the reducing agent. In order to ensure the accuracy of the test results, after the colored barium sulfate is precipitated, the excess permanganate ions in the solution are converted into a colorless state by a reducing agent, which ensures that the color change finally observed is caused only by the red mixed crystal formed by barium sulfate and permanganate ions, and the concentration change of sulfate ions in the water sample can be intuitively reflected by observing the red depth of the suspension. Therefore, when the water quality sulfate detection reagent of the present invention is used for water sample detection, it can show significant advantages such as high sensitivity, good selectivity, a wide measurement range (0~1000 mg / L) and short test time, and is very suitable for on-site rapid determination of sulfate content in water samples in various application scenarios.

[0008] Furthermore, the permanganate compound of the present invention is potassium permanganate.

[0009] Furthermore, the concentration of potassium permanganate in the colorant solution of the present invention is 20-60 mmol / L.

[0010] Furthermore, the soluble barium salt of the present invention is barium chloride, and the concentration of barium chloride in the precipitant solution is 52-240 g / L.

[0011] Furthermore, the acid solution of the present invention is hydrochloric acid.

[0012] Furthermore, the acid concentration in the precipitant solution of the present invention is 0.1 mol / L.

[0013] Furthermore, the surfactant of the present invention is an anionic surfactant and / or a nonionic surfactant.

[0014] Furthermore, the surfactant of the present invention is Triton X-100, and the concentration of Triton X-100 in the precipitant solution is greater than or equal to 3 g / L.

[0015] Accordingly, the second aspect of the present invention provides a method for preparing a water quality sulfate detection reagent, the steps comprising: (1) Preparation of colorant solution Dissolving a colorant in water and stirring evenly to obtain a colorant liquid; (2) Preparation of precipitant solution Dissolving a precipitant and a precipitant stabilizer in water and stirring evenly to obtain a precipitant solution; (3) Preparation of reducing agent The reducing agent is sieved and quantitatively packaged into reagent powder packages of 0.05~0.1g / package.

[0016] Accordingly, the third aspect of the present invention further provides a method for detecting sulfate in water quality, using the water quality sulfate detection reagent mentioned above or the water quality sulfate detection reagent prepared by the preparation method of the water quality sulfate detection reagent mentioned above, comprising the following steps: (1) Take 1.5 mL of the water sample to be tested into a test tube, add 0.2 mL of colorant solution, 0.1 mL of precipitant solution, and a packet of reducing agent in sequence, shake well, tighten the tube cap, and let it react for 1 minute; (2) Use a standard colorimetric card to perform color comparison and semi-quantitatively determine the sulfate content in the water sample to be tested; or draw a standard curve and use a colorimeter to measure and quantitatively determine the sulfate content in the water sample to be tested.

[0017] Compared with the prior art, in the water quality sulfate detection method of the present invention, a standard colorimetric card can be used to perform semi-quantitative testing on the sulfate content in various water qualities, or a UV / visible spectrophotometer, a portable water quality detector and other equipment can be used to perform quantitative determination of water quality sulfate; this detection method has a simple testing process and rapid color development, which can greatly save the testing cost of on-site monitoring.

[0018] Furthermore, the preparation method of the standard colorimetric card of the present invention comprises the steps of: ① Use pure water to prepare sulfate standard solutions with concentrations of 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively; ② Take 1.5mL of 50mg / L sulfate standard solution into the test tube, add 0.2mL colorant solution, 0.1mL precipitant solution, and a packet of reducing agent in sequence, shake well and tighten the tube cap, let it react for 1 minute, then place the test tube on a white background, observe the solution color from the side and find the corresponding standard color on the Pantone color card; ③ Repeat step ② to test the sulfate standard solutions with concentrations of 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively and find the corresponding standard colors; ④ Prepare a standard colorimetric card based on the color values ​​of standard colors at each concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the standard colorimetric card for the water quality sulfate detection reagent in Example 1 of the present invention. DETAILED DESCRIPTION

[0020] The water quality sulfate detection reagent of the present invention comprises a colorant liquid, a precipitant liquid and a reducing agent; the colorant in the colorant liquid is a permanganate compound, the precipitant liquid comprises a precipitant and a precipitation stabilizer, the precipitant is a soluble barium salt, and the precipitation stabilizer comprises an acid solution and a surfactant.

[0021] The permanganate compound is potassium permanganate. Potassium permanganate has strong oxidizing properties. If the concentration is too high, it will affect personal safety. If the concentration is too low, it will affect the degree of coloring and thus affect the sensitivity of the reagent. Therefore, the concentration of potassium permanganate in the coloring agent liquid is 20-60 mmol / L; for example, the concentration of potassium permanganate may be, but is not limited to, 20 mmol / L, 30 mmol / L, 40 mmol / L, 50 mmol / L, and 60 mmol / L; preferably, the concentration of potassium permanganate is 30-50 mmol / L.

[0022] The soluble barium salt is barium chloride, and the concentration of barium chloride in the precipitant solution is 52-240 g / L. Within this concentration range, barium chloride can ensure sufficient reaction with sulfate ions in the water sample to be tested to generate a sufficient amount of barium sulfate precipitation, so that even trace amounts of sulfate ions can be effectively detected, which improves the sensitivity of the detection.

[0023] The acid solution is hydrochloric acid; hydrochloric acid can provide the system with the necessary acidic environment, which can prevent the formation of barium carbonate and barium phosphate precipitation and improve the selectivity of the reaction; in addition, under neutral to alkaline pH conditions, when a reducing agent is used to remove excess permanganate ions, a brown suspension of manganese dioxide will be generated, which will affect the color of the suspension. Therefore, by maintaining acidic conditions, the above situation can be avoided and the sensitivity of the test results can be ensured. In addition, hydrochloric acid can provide chloride ions for the system, and chloride ions can promote the coprecipitation of permanganate and barium sulfate, which increases the speed of red mixed crystal generation and ensures the stability of the red mixed crystal structure.

[0024] The concentration of the acid in the precipitant solution is 0-0.5 mol / L. Selecting an appropriate acid concentration is crucial to ensuring the accuracy of the test results. Specifically, if the acid concentration is too high, the solubility of the barium sulfate precipitate will increase, causing part of the barium sulfate precipitate to redissolve in the solution. Therefore, the acid concentration within this range can provide the necessary acidic environment and avoid the above problems, thereby ensuring the stability of the barium sulfate precipitate and the accuracy of the test results. Preferably, the concentration of the acid in the precipitant solution is 0.1 mol / L.

[0025] Wherein, the surfactant is an anionic surfactant and / or a nonionic surfactant. The barium sulfate precipitate precipitated in the reaction will be easily adsorbed on the container. Considering that the container needs to be used repeatedly, it is necessary to add a reagent to prevent the barium sulfate precipitate from adhering. Experiments have shown that the use of a surfactant can reduce the adhesion of the precipitate.

[0026] The surfactant is a nonionic surfactant; the nonionic surfactant has an excellent effect in preventing barium sulfate from precipitating and adsorbing on the surface of the container.

[0027] The surfactant is Triton X-100, which can form an effective protective layer on the surface of the container, significantly reducing the adsorption of barium sulfate precipitation, ensuring that the container can be reused efficiently and cleanly. Specifically, when the concentration of Triton X-100 in the precipitant solution is greater than or equal to 3 g / L, the measurement result is stable.

[0028] Wherein, the reducing agent is at least one of ascorbic acid, sodium ascorbate, and sodium thiosulfate. Preferably, the reducing agent is ascorbic acid, because when ascorbic acid is added to the reaction system, the reaction is completed instantaneously, and this instantaneous reaction characteristic greatly improves the speed and accuracy of detection.

[0029] The preparation method of the water quality sulfate detection reagent of the present invention comprises the following steps: (1) Preparation of colorant solution Dissolving a colorant in water and stirring evenly to obtain a colorant liquid; (2) Preparation of precipitant solution Dissolving a precipitant and a precipitant stabilizer in water and stirring evenly to obtain a precipitant solution; (3) Preparation of reducing agent The reducing agent is sieved and quantitatively packaged into reagent powder packages of 0.05~0.1g / package.

[0030] Among them, the preparation of the colorant liquid includes: preparing a potassium permanganate solution according to the method for preparing a potassium permanganate standard stock solution in GB11892-1989, then titrating it with a sodium oxalate standard solution to determine its concentration to obtain a colorant, and then dissolving the colorant in water to obtain a colorant liquid of a target concentration; the colorant liquid is packaged in glass bottles, preferably brown glass bottles, and most preferably brown glass dropper bottles.

[0031] Specifically, the preparation of the precipitant solution includes: adding barium chloride dihydrate, hydrochloric acid, and a surfactant into water in a certain mass ratio, stirring and dissolving to obtain a precipitant solution, wherein the concentrations of barium chloride, hydrochloric acid, and the surfactant in the precipitant solution are all within the target concentration range; and the precipitant solution is packaged in glass bottles or plastic bottles.

[0032] Specifically, the preparation of the reducing agent includes: after passing the reducing agent through a 40-80 mesh sieve, quantitatively packaging the reducing agent into reducing agent powder packages using aluminum foil on an automatic powder packaging machine, with each package containing 0.05-0.1 g.

[0033] The water quality sulfate detection method of the present invention may include the following steps: (1) Take 1.5 mL of the water sample to be tested into a test tube, add 0.2 mL of colorant solution, 0.1 mL of precipitant solution, and a packet of reducing agent in sequence, shake well, tighten the tube cap, and let it react for 1 minute; (2) Use a standard colorimetric card to perform color comparison and semi-quantitatively determine the sulfate content in the water sample to be tested; or draw a standard curve and use a colorimeter to measure and quantitatively determine the sulfate content in the water sample to be tested.

[0034] The preparation method of the standard colorimetric card comprises the following steps: ① Use pure water to prepare sulfate standard solutions with concentrations of 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively; ② Take 1.5mL of 50mg / L sulfate standard solution into the test tube, add 0.2mL colorant solution, 0.1mL precipitant solution, and a packet of reducing agent in sequence, shake well and tighten the tube cap, let it react for 1 minute, then place the test tube on a white background, observe the solution color from the side and find the corresponding standard color on the Pantone color card; ③ Repeat step ② to test the sulfate standard solutions with concentrations of 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively and find the corresponding standard colors; ④ Prepare a standard colorimetric card based on the color values ​​of standard colors at each concentration.

[0035] In order to better illustrate the purpose, technical scheme and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments and drawings. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention.

[0036] Example 1 The present embodiment provides a water quality sulfate detection reagent, including a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is potassium permanganate, the precipitant liquid includes a precipitant and a precipitation stabilizer, the precipitant is barium chloride, and the precipitation stabilizer includes hydrochloric acid and Triton X-100; the concentration of potassium permanganate in the colorant liquid is 30 mmol / L, the concentration of barium chloride in the precipitant liquid is 55.4 g / L, the concentration of hydrochloric acid in the precipitant liquid is 0.1 mol / L, and the concentration of Triton X-100 in the precipitant liquid is 3g / L; the reducing agent is ascorbic acid.

[0037] This embodiment also provides a method for preparing the above-mentioned water quality sulfate detection reagent, the steps comprising: (1) Preparation of colorant liquid: Weigh 3.2g potassium permanganate into a 2L beaker, add 1L distilled water, stir with a glass rod to dissolve it; then heat and boil the prepared solution for 2 hours, pour it into a brown reagent bottle after cooling, let it stand in a dark place for 2 days, filter it with a microporous glass funnel, store the filtrate in a brown reagent bottle, titrate its concentration C with sodium oxalate standard solution, add ultrapure water to dilute its concentration to 30 mmol / L colorant solution, and fill the colorant solution into a brown glass dropper bottle; (2) Preparation of precipitant solution Dissolve 65g of barium chloride dihydrate, 100mL of 1mol / L hydrochloric acid, and 3g of Triton X-100 in water and dilute to 1L to prepare a precipitant solution, and then dispense the precipitant solution into polyethylene plastic dropper bottles; (3) Preparation of reducing agent After ascorbic acid is passed through a 40-80 mesh sieve, it is quantitatively packaged into reducing reagent powder packages using aluminum foil on an automatic powder packaging machine, with each package containing 0.05 g.

[0038] Example 2 The present embodiment provides a water quality sulfate detection reagent, including a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is potassium permanganate, the precipitant liquid includes a precipitant and a precipitation stabilizer, the precipitant is barium chloride, and the precipitation stabilizer includes hydrochloric acid and Triton X-100; the concentration of potassium permanganate in the colorant liquid is 40 mmol / L, the concentration of barium chloride in the precipitant liquid is 55.4 g / L, the concentration of hydrochloric acid in the precipitant liquid is 0.1 mol / L, and the concentration of Triton X-100 in the precipitant liquid is 3 g / L; the reducing agent is ascorbic acid.

[0039] This embodiment also provides a method for preparing the above-mentioned water quality sulfate detection reagent, the steps comprising: (1) Preparation of colorant liquid: Weigh 3.2g potassium permanganate and place it in a 2L beaker, add 1L distilled water, stir with a glass rod to dissolve it; then heat and boil the prepared solution for 2 hours, pour it into a brown reagent bottle after cooling, let it stand in a dark place for 2 days, filter it with a microporous glass funnel, store the filtrate in a brown reagent bottle, titrate its concentration C with sodium oxalate standard solution, add ultrapure water to dilute its concentration to 40 mmol / L colorant solution, and fill the colorant solution into a brown glass dropper bottle; (2) Preparation of precipitant solution Dissolve 65g of barium chloride dihydrate, 100mL of 1mol / L hydrochloric acid, and 3g of Triton X-100 in water and dilute to 1L to prepare a precipitant solution, and then dispense the precipitant solution into polyethylene plastic dropper bottles; (3) Preparation of reducing agent After ascorbic acid is passed through a 40-80 mesh sieve, it is quantitatively packaged into reducing reagent powder packages using aluminum foil on an automatic powder packaging machine, with each package containing 0.05 g.

[0040] Example 3 The present embodiment provides a water quality sulfate detection reagent, including a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is potassium permanganate, the precipitant liquid includes a precipitant and a precipitation stabilizer, the precipitant is barium chloride, and the precipitation stabilizer includes hydrochloric acid and Triton X-100; the concentration of potassium permanganate in the colorant liquid is 50 mmol / L, the concentration of barium chloride in the precipitant liquid is 55.4 g / L, the concentration of hydrochloric acid in the precipitant liquid is 0.1 mol / L, and the concentration of Triton X-100 in the precipitant liquid is 3 g / L; the reducing agent is ascorbic acid.

[0041] This embodiment also provides a method for preparing the above-mentioned water quality sulfate detection reagent, the steps comprising: (1) Preparation of colorant liquid: Weigh 3.2g potassium permanganate into a 2L beaker, add 1L distilled water, stir with a glass rod to dissolve it; then heat and boil the prepared solution for 2 hours, pour it into a brown reagent bottle after cooling, let it stand in a dark place for 2 days, filter it with a microporous glass funnel, store the filtrate in a brown reagent bottle, titrate its concentration C with sodium oxalate standard solution, add ultrapure water to dilute its concentration to 50 mmol / L colorant solution, and fill the colorant solution into a brown glass dropper bottle; (2) Preparation of precipitant solution Dissolve 65g of barium chloride dihydrate, 100mL of 1mol / L hydrochloric acid, and 3g of Triton X-100 in water and dilute to 1L to prepare a precipitant solution, and then dispense the precipitant solution into polyethylene plastic dropper bottles; (3) Preparation of reducing agent After ascorbic acid is passed through a 40-80 mesh sieve, it is quantitatively packaged into reducing reagent powder packages using aluminum foil on an automatic powder packaging machine, with each package containing 0.05 g.

[0042] Example 4 The present embodiment provides a water quality sulfate detection reagent, including a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is potassium permanganate, the precipitant liquid includes a precipitant and a precipitation stabilizer, the precipitant is barium chloride, and the precipitation stabilizer includes hydrochloric acid and Triton X-100; the concentration of potassium permanganate in the colorant liquid is 40 mmol / L, the concentration of barium chloride in the precipitant liquid is 102.28 g / L, the concentration of hydrochloric acid in the precipitant liquid is 0.1 mol / L, and the concentration of Triton X-100 in the precipitant liquid is 3 g / L; the reducing agent is ascorbic acid.

[0043] This embodiment also provides a method for preparing the above-mentioned water quality sulfate detection reagent, the steps comprising: (1) Preparation of colorant liquid: Weigh 3.2g potassium permanganate and place it in a 2L beaker, add 1L distilled water, stir with a glass rod to dissolve it; then heat and boil the prepared solution for 2 hours, pour it into a brown reagent bottle after cooling, let it stand in a dark place for 2 days, filter it with a microporous glass funnel, store the filtrate in a brown reagent bottle, titrate its concentration C with sodium oxalate standard solution, add ultrapure water to dilute its concentration to 40 mmol / L colorant solution, and fill the colorant solution into a brown glass dropper bottle; (2) Preparation of precipitant solution Dissolve 120g of barium chloride dihydrate, 100mL of 1mol / L hydrochloric acid, and 3g of Triton X-100 in water and dilute to 1L to prepare a precipitant solution, and then dispense the precipitant solution into polyethylene plastic dropper bottles; (3) Preparation of reducing agent After ascorbic acid is passed through a 40-80 mesh sieve, it is quantitatively packaged into reducing reagent powder packages using aluminum foil on an automatic powder packaging machine, with each package containing 0.05 g.

[0044] Example 5 The present embodiment provides a water quality sulfate detection reagent, including a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is potassium permanganate, the precipitant liquid includes a precipitant and a precipitation stabilizer, the precipitant is barium chloride, and the precipitation stabilizer includes hydrochloric acid and Triton X-100; the concentration of potassium permanganate in the colorant liquid is 40 mmol / L, the concentration of barium chloride in the precipitant liquid is 204.55 g / L, the concentration of hydrochloric acid in the precipitant liquid is 0.1 mol / L, and the concentration of Triton X-100 in the precipitant liquid is 3 g / L; the reducing agent is ascorbic acid.

[0045] This embodiment also provides a method for preparing the above-mentioned water quality sulfate detection reagent, the steps comprising: (1) Preparation of colorant liquid: Weigh 3.2g potassium permanganate and place it in a 2L beaker, add 1L distilled water, stir with a glass rod to dissolve it; then heat and boil the prepared solution for 2 hours, pour it into a brown reagent bottle after cooling, let it stand in a dark place for 2 days, filter it with a microporous glass funnel, store the filtrate in a brown reagent bottle, titrate its concentration C with sodium oxalate standard solution, add ultrapure water to dilute its concentration to 40 mmol / L colorant solution, and fill the colorant solution into a brown glass dropper bottle; (2) Preparation of precipitant solution Dissolve 240g of barium chloride dihydrate, 100mL of 1mol / L hydrochloric acid, and 3g of Triton X-100 in water and dilute to 1L to prepare a precipitant solution, and then dispense the precipitant solution into polyethylene plastic dropper bottles; (3) Preparation of reducing agent After ascorbic acid is passed through a 40-80 mesh sieve, it is quantitatively packaged into reducing reagent powder packages using aluminum foil on an automatic powder packaging machine, with each package containing 0.05 g.

[0046] Example 6 The present embodiment provides a water quality sulfate detection reagent, including a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is potassium permanganate, the precipitant liquid includes a precipitant and a precipitation stabilizer, the precipitant is barium chloride, and the precipitation stabilizer includes nitric acid and Triton X-100; the concentration of potassium permanganate in the colorant liquid is 30 mmol / L, the concentration of barium chloride in the precipitant liquid is 55.4 g / L, the concentration of nitric acid in the precipitant liquid is 0.1 mol / L, and the concentration of Triton X-100 in the precipitant liquid is 3g / L; the reducing agent is ascorbic acid.

[0047] This embodiment also provides a method for preparing the above-mentioned water quality sulfate detection reagent, the steps comprising: (1) Preparation of colorant liquid: Weigh 3.2g potassium permanganate into a 2L beaker, add 1L distilled water, stir with a glass rod to dissolve it; then heat and boil the prepared solution for 2 hours, pour it into a brown reagent bottle after cooling, let it stand in a dark place for 2 days, filter it with a microporous glass funnel, store the filtrate in a brown reagent bottle, titrate its concentration C with sodium oxalate standard solution, add ultrapure water to dilute its concentration to 30 mmol / L colorant solution, and fill the colorant solution into a brown glass dropper bottle; (2) Preparation of precipitant solution Dissolve 65g of barium chloride dihydrate, 100mL of 1mol / L nitric acid, and 3g of Triton X-100 in water and dilute to 1L to prepare a precipitant solution, and then dispense the precipitant solution into polyethylene plastic dropper bottles; (3) Preparation of reducing agent After ascorbic acid is passed through a 40-80 mesh sieve, it is quantitatively packaged into reducing reagent powder packages using aluminum foil on an automatic powder packaging machine, with each package containing 0.05 g.

[0048] Comparative Example 1 The comparative example provides a water quality sulfate detection reagent, comprising a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is potassium permanganate, the precipitant liquid comprises a precipitant and a precipitation stabilizer, the precipitant is barium chloride, and the precipitation stabilizer comprises hydrochloric acid and Triton X-100; the concentration of potassium permanganate in the colorant liquid is 30 mmol / L, the concentration of barium chloride in the precipitant liquid is 55.4 g / L, the concentration of hydrochloric acid in the precipitant liquid is 0.1 mol / L, and the concentration of Triton X-100 in the precipitant liquid is 3g / L; the reducing agent is oxalic acid.

[0049] This comparative example also provides a method for preparing the above-mentioned water quality sulfate detection reagent, the steps comprising: (1) Preparation of colorant liquid: Weigh 3.2g potassium permanganate into a 2L beaker, add 1L distilled water, stir with a glass rod to dissolve it; then heat and boil the prepared solution for 2 hours, pour it into a brown reagent bottle after cooling, let it stand in a dark place for 2 days, filter it with a microporous glass funnel, store the filtrate in a brown reagent bottle, titrate its concentration C with sodium oxalate standard solution, add ultrapure water to dilute its concentration to 30 mmol / L colorant solution, and fill the colorant solution into a brown glass dropper bottle; (2) Preparation of precipitant solution Dissolve 65g of barium chloride dihydrate, 100mL of 1mol / L hydrochloric acid, and 3g of Triton X-100 in water and dilute to 1L to prepare a precipitant solution, and then dispense the precipitant solution into polyethylene plastic dropper bottles; (3) Preparation of reducing agent After oxalic acid is passed through a 40-80 mesh sieve, it is quantitatively packaged into reducing reagent powder packages using aluminum foil on an automatic powder packaging machine, with each package containing 0.05 g.

[0050] Comparative Example 2 The comparative example provides a water quality sulfate detection reagent, comprising a colorant liquid, a precipitant liquid, and a reducing agent; the colorant in the colorant liquid is potassium permanganate, the precipitant liquid comprises a precipitant and a precipitation stabilizer, the precipitant is barium chloride, and the precipitation stabilizer comprises hydrochloric acid and Triton X-100; the concentration of potassium permanganate in the colorant liquid is 30 mmol / L, the concentration of barium chloride in the precipitant liquid is 55.4 g / L, the concentration of hydrochloric acid in the precipitant liquid is 1 mol / L, and the concentration of Triton X-100 in the precipitant liquid is 3g / L; the reducing agent is ascorbic acid.

[0051] This comparative example also provides a method for preparing the above-mentioned water quality sulfate detection reagent, the steps comprising: (1) Preparation of colorant liquid: Weigh 3.2g potassium permanganate into a 2L beaker, add 1L distilled water, stir with a glass rod to dissolve it; then heat and boil the prepared solution for 2 hours, pour it into a brown reagent bottle after cooling, let it stand in a dark place for 2 days, filter it with a microporous glass funnel, store the filtrate in a brown reagent bottle, titrate its concentration C with sodium oxalate standard solution, add ultrapure water to dilute its concentration to 30 mmol / L colorant solution, and fill the colorant solution into a brown glass dropper bottle; (2) Preparation of precipitant solution Dissolve 65g of barium chloride dihydrate, 100mL of 10mol / L hydrochloric acid, and 3g of Triton X-100 in water and dilute to 1L to prepare a precipitant solution, and then dispense the precipitant solution into polyethylene plastic dropper bottles; (3) Preparation of reducing agent After ascorbic acid is passed through a 40-80 mesh sieve, it is quantitatively packaged into reducing reagent powder packages using aluminum foil on an automatic powder packaging machine, with each package containing 0.05 g.

[0052] Use pure water to prepare sulfate standard solutions with concentrations of 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L, respectively, take 1.5 mL and add them to the test tubes, respectively, add the water quality sulfate detection reagents (0.2 mL colorant solution, 0.1 mL precipitant solution, and a pack of reducing agent) of Examples 1 to 6 and Comparative Examples 1 to 2, respectively, shake well and tighten the tube cap, and let it stand for 1 minute to react; use the WF30 portable spectrophotometer produced by Shenzhen Weifu Optoelectronics Technology Co., Ltd. and select a 1 cm cuvette as the sample pool, contact the 1 cm cuvette with the photometric part of the equipment, and measure the chromaticity of the sample a sample. And use a 1 cm cuvette filled with pure water as a reference sample, measure its chromaticity a water; and correct by subtracting a water from a sample; that is, use Δa=a sample-a water as the red intensity of the colored suspension in each standard solution sample; the test results are shown in Table 1.

[0053] Table 1

[0054] From the results in Table 1, it can be seen that the water quality sulfate detection reagents of Examples 1 to 6 show a stable and increasing Δa value (red intensity) in sulfate solutions within a concentration range of 50 to 1000 mg / L, that is, as the sulfate concentration increases, the color change produced by the reagent is also correspondingly enhanced, which indicates that the detection reagent of the present invention can provide consistent and reliable response characteristics within a concentration range of 0 to 1000 mg / L. In addition, the water quality sulfate detection reagents of Examples 1 to 5 can still show a stable and increasing Δa value (red intensity) when detecting sulfate samples within a concentration range of 1000 to 2000 mg / L, which indicates that the water quality sulfate detection reagents in Examples 1 to 5 can be effectively used for quantitative analysis of sulfate within a concentration range of 0 to 2000 mg / L. However, under the high concentration condition of 2000 mg / L, the Δa value of Example 6 is significantly lower than that of Example 1, which indicates that the sensitivity of the water quality sulfate detection reagent of Example 6 decreases at high concentrations. This shows that compared with the selection of nitric acid, the selection of hydrochloric acid containing chloride ions helps to promote the co-precipitation reaction between permanganate and barium sulfate, thereby accelerating the formation of red mixed crystals and enhancing their structural stability, thereby improving the sensitivity and response efficiency of the reagent under high concentration conditions.

[0055] Comparing the data of Comparative Example 1, it is found that the Δa values ​​are very close at all concentrations, and there is almost no difference between low concentrations (50 to 200 mg / L) and high concentrations (1000 to 2000 mg / L); this indicates that the reagent of Comparative Example 1 is insensitive to changes in sulfate concentration. This insensitivity may be because the oxalic acid reducing agent used in Comparative Example 1 cannot quickly and effectively reduce the remaining permanganate ions to a colorless state. Due to the insufficient reduction efficiency of oxalic acid, the color reaction cannot be significantly distinguished regardless of the change in sulfate concentration, thereby affecting the sensitivity of the detection results.

[0056] By comparing the data of Example 1 and Comparative Example 2, it is found that at a concentration of 50 to 2000 mg / L, the Δa value of Comparative Example 2 is generally lower than that of Example 1, especially at high concentrations (500 to 2000 mg / L), its growth trend is not as obvious as that of Example 1, and even decreases at the highest concentration; this may be because the high concentration of hydrochloric acid promotes the dissolution of the formed precipitate, thereby reducing the red mixed crystals, resulting in inaccurate measurement results and reduced sensitivity.

[0057] The four samples were further tested using the water quality sulfate detection reagent of Example 1.

[0058] (1) Actual sample Sample A: hot spring water; Sample B: industrial boiler water; Sample C: circulating cooling water; Sample D: circulating fluid of biological desulfurization system.

[0059] (2) Preparation of standard colorimetric cards The steps include: ① Use pure water to prepare sulfate standard solutions with concentrations of 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively; ② Take 1.5 mL of 50 mg / L sulfate standard solution into a test tube, add 0.2 mL of colorant solution, 0.1 mL of precipitant solution, and a packet of reducing agent in Example 1 in sequence, shake well and tighten the tube cap, let it react for 1 minute, then place the test tube on a white background, observe the solution color from the side and find the corresponding standard color on the Pantone color card; ③ Repeat step ② to test the sulfate standard solutions with concentrations of 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively and find the corresponding standard colors; ④According to the color value of each concentration standard color, Figure 1 Standard colorimetric chart shown.

[0060] (3) Drawing of standard curve This sample is not suitable for the visible absorption photometry method of measuring transmitted light because the color development product is a suspended particle. In order to numerically evaluate the color intensity of the suspension, a portable spectrophotometer is used, and a 1cm cuvette is used as a sample cell. The 1cm cuvette is in contact with the photometric part of the equipment to measure the chromaticity a sample. First, water is placed in a 1cm cuvette, the chromaticity a water is measured, and the correction is made by subtracting a water from a sample; that is, Δa=a sample-a water is used as the red intensity of the colored suspension. The steps include: a. Use pure water to prepare sulfate standard solutions with concentrations of 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively; b. Take 1.5 mL of 50 mg / L sulfate standard solution into a test tube, add 0.2 mL of colorant solution, 0.1 mL of precipitant solution, and a packet of reducing agent in Example 1, shake well, tighten the tube cap, let it stand for 1 minute, and then test Δa on a portable spectrocolorimeter; c. Repeat step (b) to test the sulfate standard solutions with concentrations of 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively; d. Draw a standard curve based on the relationship between color difference (Δa) and concentration (C). The standard curve equation is: Δa = 1E-08C 3 -5E-05C 2 +0.0531C+1.1136, the test range is 0~2000mg / L, where C is the sulfate concentration and Δa is the sample chromaticity.

[0061] (4) Sample testing Take 1.5mL of four samples respectively and add them to the colorimetric tubes respectively, add 0.2mL colorant solution, 0.1mL precipitant solution and a pack of reducing agent of Example 1, shake well and tighten the tube cap, let it stand for 1 minute and place the colorimetric tube on a white PVC plate to remove the background color interference, observe the color of the solution from the side, select the color scale of the colorimetric card with the same or similar color tone as the solution in the tube to indicate the concentration of sulfate in the sample solution, and use a portable spectrophotometer to test the color of the sample, and substitute it into the above standard curve equation to calculate the sulfate content; and use the 4.2 ion chromatography method in GB / T5750.5-2023 and the sulfate test paper (200~1600mg / L) produced by Guangdong Huankai Biotechnology Co., Ltd. for comparison. Among them, if the water sample test result exceeds the range, it can be appropriately diluted and tested. The test results of the four water samples are shown in Table 2 below.

[0062] Table 2 Test results of four water samples

[0063] Note: If the actual sample D is out of range, dilute it 10 times and retest. The above water sample D test results are obtained by multiplying the measured data by the dilution factor. When testing samples by ion chromatography, it is necessary to dilute the samples with water to a range of 0.75~12.0mg / L.

[0064] As can be seen from the results of Table 2, when using the water quality sulfate detection reagent of the present invention, the test results of the colorimetric card method, the portable instrument method, and the ion chromatography method are relatively consistent, proving the reliability and accuracy of the water quality sulfate detection reagent of the present invention for detecting water quality sulfate. Moreover, compared with the traditional test paper method, the colorimetric card method and the portable instrument method of the present invention can more sensitively detect lower concentrations of sulfate, providing higher detection accuracy. Due to its fast, accurate and sensitive characteristics, the water quality sulfate detection reagent of the present invention is very suitable for a variety of application scenarios, including but not limited to boiler water management, hot spring water measurement, and circulating fluid management of biological desulfurization devices.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A water quality sulfate detection reagent, characterized in that: It comprises a colorant liquid, a precipitant liquid and a reducing agent; the colorant in the colorant liquid is a permanganate compound, the precipitant liquid comprises a precipitant and a precipitation stabilizer, the precipitant is a soluble barium salt, and the precipitation stabilizer comprises an acid solution and a surfactant; the acid solution concentration in the precipitant liquid is 0-0.5 mol / L, and the reducing agent is at least one of ascorbic acid, sodium ascorbate and sodium thiosulfate.

2. The water quality sulfate detection reagent according to claim 1, characterized in that: The permanganate compound is potassium permanganate; the concentration of potassium permanganate in the colorant solution is 20-60 mmol / L.

3. The water quality sulfate detection reagent according to claim 1, characterized in that: The soluble barium salt is barium chloride, and the concentration of barium chloride in the precipitant solution is 52-240 g / L.

4. The water quality sulfate detection reagent according to claim 1, characterized in that: The acid solution is hydrochloric acid.

5. The water quality sulfate detection reagent according to claim 1, characterized in that: The acid concentration in the precipitant solution is 0.1 mol / L.

6. The water quality sulfate detection reagent according to claim 1, characterized in that: The surfactant is an anionic surfactant and / or a nonionic surfactant.

7. The water quality sulfate detection reagent according to claim 1, characterized in that: The surfactant is Triton X-100, and the concentration of Triton X-100 in the precipitant solution is greater than or equal to 3 g / L.

8. The method for preparing a water quality sulfate detection reagent according to any one of claims 1 to 7, characterized in that the steps include: (1) Preparation of colorant solution Dissolving the colorant in water and stirring evenly to obtain a colorant liquid; (2) Preparation of precipitant solution Dissolving the precipitant and the precipitation stabilizer in water and stirring evenly to obtain a precipitant solution; (3) Preparation of reducing agent The reducing agent is sieved and quantitatively packaged into reagent powder packages of 0.05-0.1 g / package.

9. A method for detecting sulfate in water, characterized in that: The water quality sulfate detection reagent prepared by the preparation method of the water quality sulfate detection reagent according to any one of claims 1 to 7 or the water quality sulfate detection reagent according to claim 8 comprises the following steps: (1) Take 1.5 mL of the water sample to be tested into a test tube, add 0.2 mL of the colorant solution, 0.1 mL of the precipitant solution, and a pack of the reducing agent in sequence, shake well, tighten the tube cap, and let it react for 1 minute; (2) Use a standard colorimetric card to perform color comparison and semi-quantitatively determine the sulfate content in the water sample to be tested; or draw a standard curve and use a colorimeter to measure and quantitatively determine the sulfate content in the water sample to be tested.

10. The method for detecting sulfate in water according to claim 9, characterized in that: The preparation method of the standard colorimetric card comprises the steps of: ① Use pure water to prepare sulfate standard solutions with concentrations of 50 mg / L, 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively; ② Take 1.5mL of 50mg / L sulfate standard solution into a test tube, add 0.2mL of the colorant solution, 0.1mL of the precipitant solution, and a pack of the reducing agent in sequence, shake well and tighten the tube cap, let it react for 1 minute, then place the test tube on a white background, observe the solution color from the side and find the corresponding standard color on the Pantone color card; ③ Repeat step ② to test the sulfate standard solutions with concentrations of 100 mg / L, 200 mg / L, 500 mg / L, 1000 mg / L, and 2000 mg / L respectively and find the corresponding standard colors; ④ Prepare a standard colorimetric card based on the color values ​​of standard colors at each concentration.

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