A method for degrading chlorothalonil in water

Abstract

The present application relates to sewage treatment technical field, provide a kind of degradation of chlorothalonil in water method.The present application provides a kind of method for treating chlorothalonil in water using papermaking by-product sodium lignosulfonate: sodium lignosulfonate is mixed with chlorothalonil aqueous solution, the content of sodium lignosulfonate is 1.00~100.49mg / L, under high-pressure mercury lamp, the photolysis half-life of chlorothalonil is 156.82~3.82min, compared with control group (chlorothalonil aqueous solution without sodium lignosulfonate) degradation rate increases 1.09~85.01 times, and no toxic metabolite 4-OH chlorothalonil is generated.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically, to a method for degrading chlorothalonil in water. Background Technology

[0002] Chlorothalonil (CTL), developed as a substitute for organotin compounds, is a third-generation, highly effective, broad-spectrum fungicide widely used worldwide. It is primarily used to prevent fungal diseases in fruits, vegetables, and other plants. Its mechanism of action involves interacting with glyceraldehyde-3-phosphate dehydrogenase in fungal cells, disrupting enzyme activity and causing metabolic disruption that leads to cell death. Chlorothalonil is highly toxic to aquatic organisms and amphibians, and exhibits strong mutagenicity in humans. Long-term, high-volume use of chlorothalonil can lead to aquatic pollution. The metabolite of chlorothalonil is 4-OH chlorothalonil, which is far more toxic than the parent compound and is readily produced during degradation. Currently, the main methods for treating chlorothalonil in water are biodegradation and chemical degradation. Biodegradation utilizes microorganisms to treat chlorothalonil in water, but the main degradation product is highly toxic 4-OH chlorothalonil, which is detrimental to the environment and aquatic organisms. Furthermore, as a fungicide, chlorothalonil requires specific treatment of the microorganisms to reach an active state, increasing treatment costs. Treatment with novel materials (such as nanomaterials) can also easily produce 4-hydroxychlorothalonil, increasing environmental risks. Other treatment technologies, including activated carbon adsorption and coagulation, cannot ultimately degrade the chlorothalonil parent compound. Summary of the Invention

[0003] To safely and efficiently remove chlorothalonil from water, this invention provides a method for the efficient degradation of chlorothalonil in water using the inexpensive surfactant sodium lignosulfonate.

[0004] To achieve the objective of this invention, this invention provides a method for degrading chlorothalonil in water, which involves adding sodium lignosulfonate to the water to be treated containing chlorothalonil and then subjecting it to light treatment.

[0005] The molar ratio of chlorothalonil to sodium lignosulfonate is 1:1 to 1:100, and the concentration of chlorothalonil in the water to be treated is less than 0.5 mg / L.

[0006] Preferably, the molar ratio of chlorothalonil to sodium lignosulfonate is 1:1, 1:5, 1:10, 1:20, 1:50 or 1:100.

[0007] In the aforementioned method, the concentration of chlorothalonil in the water to be treated is 1.88 μmol / L, and the content of added sodium lignosulfonate is ≤100.49 mg / L (preferably 1.00~100.49 mg / L).

[0008] The aforementioned method involves dissolving sodium lignosulfonate into an aqueous solution or adding it directly to the water to be treated.

[0009] Furthermore, the temperature of the water to be treated is 20~28℃ (preferably 25℃).

[0010] Furthermore, sodium lignosulfonate was added to the water to be treated containing chlorothalonil, and after ultrasonic dissolution, it was subjected to light treatment.

[0011] Preferably, the ultrasonic conditions are: power 600W, operating frequency 40KHz.

[0012] In this invention, the illumination can be high-pressure mercury lamp irradiation, or xenon lamp irradiation or ultraviolet lamp irradiation. High-pressure mercury lamp irradiation is preferred.

[0013] Furthermore, the illuminance of the high-pressure mercury lamp is 8000~100001x, and the power is 150W.

[0014] Furthermore, the xenon lamp has a luminous intensity of 6000~7500 lx and a power of 500W.

[0015] Furthermore, the UV lamp has a light intensity of 75~95 lx and a power of 10W.

[0016] This invention also provides the application of sodium lignosulfonate in the degradation of chlorothalonil.

[0017] The mechanism of action of sodium lignosulfonate on chlorothalonil is as follows: when sodium lignosulfonate aqueous solution is exposed to light, it generates cavities, which directly participate in the photochemical degradation of chlorothalonil without generating highly toxic 4-hydroxychlorothalonil, and thus promotes the degradation.

[0018] Sodium ligninsulfonate (SL) is an anionic surfactant. Its sulfonic acid groups make it readily soluble in water. Its molecular structure possesses both hydrophilic groups (such as sulfonic acid groups, phenyl hydroxyl groups, carboxyl groups, and alcohol hydroxyl groups) and hydrophobic groups (such as aromatic, aliphatic, and carbon chain groups), thus exhibiting excellent surface activity. Sodium ligninsulfonate shows broad application prospects in many fields, especially in the preparation of polymers and concrete, where it is widely used as an admixture and plays a crucial role. Compared to other admixtures, sodium ligninsulfonate has many advantages such as low cost and environmental friendliness, making it highly favored in industrial production.

[0019] Other surfactants, such as Tween 20, Tween 80, sodium dodecylbenzenesulfonate, calcium dodecylbenzenesulfonate, and PVA-1788, have no significant effect on the photodegradation of chlorothalonil.

[0020] By employing the above technical solution, the present invention has at least the following advantages and beneficial effects: Based on the photodegradation phenomenon of chlorothalonil aqueous solution under artificial light source conditions, this invention provides a method for promoting the degradation of chlorothalonil using sodium lignosulfonate. Sodium lignosulfonate is mixed with chlorothalonil aqueous solution, and the content of sodium lignosulfonate is 1.00~100.49 mg / L. Under high-pressure mercury lamp, the photodegradation half-life of chlorothalonil is 156.82~3.82 min, which is 1.09~85.01 times higher than that of the control group (chlorothalonil aqueous solution without sodium lignosulfonate), and no highly toxic metabolite 4-OH chlorothalonil is produced. Detailed Implementation

[0021] This invention provides a method for treating chlorothalonil, an organic pollutant in water. More specifically, this invention relates to a method for treating chlorothalonil-contaminated wastewater using inexpensive sodium lignosulfonate, including pretreatment of natural water bodies and agricultural water pollution, as well as high-concentration industrial pollution.

[0022] The present invention adopts the following technical solution: A method for treating water with chlorothalonil using sodium lignosulfonate: The sodium lignosulfonate is dissolved into an aqueous solution or directly added to the water to be treated. The concentration of chlorothalonil is 1.88 μmol / L, and the dosage of sodium lignosulfonate is 1.00~100.49 mg / L. Under the condition of high-pressure mercury lamp irradiation intensity of 8000~10000 lx, the photodegradation half-life of chlorothalonil is 156.82~3.82 min, which is 1.09~85.01 times higher than that of the control group (chlorothalonil aqueous solution without sodium lignosulfonate), and no highly toxic metabolite 4-OH chlorothalonil is produced.

[0023] Furthermore, the water to be treated is ultrapure water.

[0024] Furthermore, the illumination is provided by a high-pressure mercury lamp.

[0025] Furthermore, chlorothalonil and sodium lignosulfonate are mixed in a molar ratio of 1:1 to 1:100, preferably in a molar ratio of 1:1, 1:5, 1:10, 1:20, 1:50 or 1:100.

[0026] Furthermore, the content of sodium lignosulfonate in the 1.88 μmol / L chlorothalonil aqueous solution is ≤100.49 mg / L, more preferably 1.00~100.49 mg / L.

[0027] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available products.

[0028] Example 1: Different concentrations of sodium lignosulfonate under high-pressure mercury lamp irradiation can promote the photodegradation of chlorothalonil aqueous solution.

[0029] A standard solution of chlorothalonil and sodium lignosulfonate was prepared with methanol to a concentration of 500 mg / L. A standard solution of sodium lignosulfonate was prepared with ultrapure water to a concentration of 500 mg / L. A certain amount of each standard solution was transferred to a 100 mL stoppered volumetric flask. The concentration of chlorothalonil and sodium lignosulfonate was set at 1.88 μmol / L. The chlorothalonil:sodium lignosulfonate molar ratios of 1:0, 1:1, 1:5, 1:10, 1:20, 1:50, and 1:100 were added to the stock solution. After dilution with pure water, the solution was solubilized by ultrasound (600 W, 40 kHz) for 3 minutes to ensure homogeneity, resulting in a mixed solution of chlorothalonil and sodium lignosulfonate. 5 mL of the prepared mixed reaction solution was transferred to a stoppered quartz test tube and subjected to photolysis under a high-pressure mercury lamp. A dark control group was also established. High-pressure mercury lamp illuminance of 8000~10000 lx, power of 150W, temperature of 25℃. Sampling times were set at 0, 120, 240, 360, 480, 600, and 720 min for chlorothalonil to sodium lignosulfonate molar ratios of 1:0 and 1:1, respectively; at 1:5 and 1:10, respectively; and at 0, 30, 60, 90, 120, 150, and 180 min for a chlorothalonil to sodium lignosulfonate molar ratio of 1:20, respectively. The molar ratios of chlorothalonil to sodium lignosulfonate were 1:50 and 1:100, with sampling times of 0, 3, 6, 9, 12, 15, and 18 min, respectively. In the mixed system of chlorothalonil (1.88 μmol / L) and sodium lignosulfonate, the addition of sodium lignosulfonate at molar ratios of 1, 5, 10, 20, 50, and 100 times to a 1.88 μmol / L chlorothalonil solution increased the degradation rate of chlorothalonil by 1.09, 5.37, 12.90, 30.2, 64.67, and 85.01 times, respectively, under high-pressure mercury lamp irradiation. The degradation rate was positively correlated with the dosage of sodium lignosulfonate in the system, indicating that the higher the dosage of sodium lignosulfonate, the more significant the photosensitization effect.

[0030] Photosensitive degradation mechanism of sodium lignosulfonate on chlorothalonil aqueous solution

[0031] Chlorothalonil standard was prepared into a standard solution with a concentration of 500 mg / L using methanol, sodium lignosulfonate standard was prepared into a standard solution with a concentration of 500 mg / L using ultrapure water, and potassium iodide standard was prepared.

[0032] Since iodide ions can effectively form iodine, they can be used to assess the participation of holes in photocatalytic reactions, as shown in the following reaction equation: <![CDATA[I ● +I 1- →I2 ●- ]]> <![CDATA[h++I2 ●- →I2]]> Under dark conditions, chlorothalonil, chlorothalonil and sodium lignosulfonate, chlorothalonil and potassium iodide, and chlorothalonil, potassium iodide, and sodium lignosulfonate solutions showed no degradation of chlorothalonil within a certain time. Aqueous solutions of chlorothalonil (1.88 μmol / L) mixed with sodium lignosulfonate and potassium iodide at molar ratios of 1:0:0, 1:1:0, 1:0:1, and 1:1:1 were prepared and subjected to photodegradation under high-pressure mercury lamp irradiation. Under high-pressure mercury lamp irradiation, the half-life of chlorothalonil alone was 285.25 min; when chlorothalonil was mixed with sodium lignosulfonate, the half-life decreased to 149.06 min; when chlorothalonil was mixed with potassium iodide, the half-life was 185.33 min; and when chlorothalonil, potassium iodide, and sodium lignosulfonate were mixed, the half-life was 162.71 min. This indicates that potassium iodide can promote the photodegradation of chlorothalonil, shortening its half-life from 285.25 min to 185.33 min and increasing the degradation rate by 53.9%. In the sodium lignosulfonate reaction system, however, the half-life of chlorothalonil increased from 149.06 min to 162.71 min, and the degradation rate decreased by 8.4%. It is speculated that light exposure to the sodium lignosulfonate aqueous solution generates cavities, which directly participate in the photochemical degradation of chlorothalonil, thus promoting its degradation.

[0033] Degradation of chlorothalonil aqueous solution by sodium lignosulfonate under xenon lamp and ultraviolet lamp irradiation

[0034] A standard solution of chlorothalonil was prepared with methanol to a concentration of 500 mg / L, and a standard solution of sodium lignosulfonate was prepared with ultrapure water to a concentration of 500 mg / L. A certain amount of each chlorothalonil and sodium lignosulfonate standard solution was transferred to a 100 mL stoppered volumetric flask. Assuming a concentration of 1.88 μmol / L for both chlorothalonil and sodium lignosulfonate, the mother liquor was added at chlorothalonil:sodium lignosulfonate molar ratios of 1:0, 1:1, 1:5, 1:10, 1:20, 1:50, and 1:100. After dilution with pure water, the mixture was ultrasonically dissolved for 3 minutes to ensure homogeneity, resulting in a mixed solution of chlorothalonil and sodium lignosulfonate. 5 mL of the prepared mixed reaction solution was transferred to a stoppered quartz test tube and subjected to photolysis under a xenon lamp and an ultraviolet lamp. When xenon lamp irradiation intensity was 6000~7500 lx and power was 500 W, and ultraviolet lamp irradiation intensity was 75~95 lx and power was 10 W, the degradation rate of chlorothalonil was increased by 0.7 times, 3.70 times, 6.83 times, 12.86 times, 30.06 times and 48.68 times respectively under xenon lamp irradiation, and by 1.9 times, 11.4 times, 17.55 times, 34.95 times, 100.78 times and 145.78 times respectively under ultraviolet lamp irradiation (Table 1).

[0035] Table 1. Degradation of chlorothalonil aqueous solution by sodium lignosulfonate under xenon lamp and ultraviolet lamp irradiation.

[0036] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for degrading chlorothalonil in water, characterized in that, Sodium lignosulfonate was added to the water to be treated containing chlorothalonil, and then subjected to light treatment. The molar ratio of chlorothalonil to sodium lignosulfonate is 1:1, 1:5, 1:10, 1:20, 1:50, or 1:

100. The concentration of chlorothalonil in the water to be treated is 1.88 μmol / L. The content of sodium lignosulfonate added is 1.00~100.49 mg / L. The water temperature to be treated is 20~28℃. Sodium lignosulfonate is dissolved into an aqueous solution and added to the water to be treated. The illumination is xenon lamp irradiation with a light intensity of 6000~7500 lx and a power of 500 W.

2. The method according to claim 1, characterized in that, Sodium lignosulfonate was added to the water containing chlorothalonil, and after ultrasonic dissolution, it was subjected to light treatment.

3. The method according to claim 2, characterized in that, Ultrasonic power 600W, operating frequency 40KHz.

4. The application of sodium lignosulfonate in the degradation of chlorothalonil, characterized in that, Sodium lignosulfonate was added to the water to be treated containing chlorothalonil, and then subjected to light treatment. The molar ratio of chlorothalonil to sodium lignosulfonate is 1:1, 1:5, 1:10, 1:20, 1:50, or 1:

100. The concentration of chlorothalonil in the water to be treated is 1.88 μmol / L. The content of sodium lignosulfonate added is 1.00~100.49 mg / L. The water temperature to be treated is 20~28℃. Sodium lignosulfonate is dissolved into an aqueous solution and added to the water to be treated. The illumination is xenon lamp irradiation with a light intensity of 6000~7500 lx and a power of 500 W.

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