A method for treating dibenzo-type organic pollutants in a water body

Abstract

The application discloses a method for treating dibenzene organic pollutants in water bodies, which comprises the following steps: electrolyzing wastewater to be treated and adding dithionite to carry out a redox reaction to obtain purified water; and the wastewater to be treated contains sodium chloride and dibenzene organic pollutants. The method for treating dibenzene organic pollutants in water bodies is carried out under normal temperature and pressure, is mild in reaction, is environmentally friendly, is easy to operate, is low in cost, has good degradation effect on dibenzene organic pollutants in the environment, and has great application potential in the field of environmental pollution treatment.

Description

Technical Field

[0001] This invention relates to the field of pollution treatment technology, and in particular to a method for treating dibenzo[a]oxa organic pollutants in water bodies. Background Technology

[0002] Persistent dibenzo[a]organic pollutants (PCPs) persist in the environment for a long time, pose a significant hazard, are difficult to treat, and exhibit bioaccumulation. Research on treatment technologies for these pollutants has been a hot topic in the environmental science and technology community. Among them, advanced oxidation processes (AOPs) possess the potential and capability to treat PCPs due to their ability to generate highly reactive free radicals.

[0003] Advanced oxidation processes have been widely used to remove dibenzo[a]oxalools (DAOs) from drinking water and wastewater. These pollutants are primarily generated in situ from highly reactive oxygen species, such as hydroxyl radicals (·OH) and sulfate radicals (SO4). ·- ), superoxide radicals (O2) ·- ) and singlet oxygen ( 1 O2). SO4 ·- It possesses advantages such as high stability, long lifespan, and high reactivity, utilizing SO4 ·- The degradation of dibenzo[a]oxane organic pollutants is a relatively new field that is gradually developing both domestically and internationally. Compared to ·OH, SO42- ·- It has a long lifetime (half-life of 4s) and a standard redox potential of 2.5V, which is close to that of the strong oxidizing agent ·OH.

[0004] Previous studies have shown that Cl·, ClO·, and Cl2 are produced by chlorination. ·- It has a good removal effect on dibenzo[a]pyrene organic pollutants in wastewater. Chlorination and SO42- ·- It also has the potential to combine. First, chloride ions can react with sulfate radicals to generate chlorine radicals (Equation 1). Chloride ions and chlorine radicals can interconvert to generate dichloro radical anions (Equation 2). Chlorine radicals can react with water and hydroxyl radicals to generate hypochlorite radicals (Equations 3 and 4), and hypochlorite radicals can also be converted into hydroxyl radicals and chloride ions (Equation 5).

[0005] Cl - +SO4 ·- →SO4 2- +Cl· (Equation 1)

[0006] Cl · +Cl -- →Cl2 ·- (Equation 2)

[0007] Cl · +OH -→ClOH ·- (Equation 3)

[0008] Cl · +H₂O→ClOH ·- +H + (Equation 4)

[0009] ClOH ·- →HO · +Cl - (Equation 5)

[0010] SO4 ·- Sulfate radicals can be produced by the decomposition of persulfates and sulfites under conditions of heating, ultraviolet light irradiation, or activation by metals. Sulfites include sulfites and dithionites (DTN). In practical applications, sulfate radicals are mainly generated in two ways: one is through energy excitation, primarily involving light, heat, and ultrasound; the other is through the activation and decomposition of persulfates by transition metal ions, such as cobalt ions (Co). 2+ ferrous ions Fe 2+ Ni ions + However, both methods have their own drawbacks. Energy-activated dithionite technology has high energy consumption and demanding technical conditions; the metal toxicity of transition metals introduced in transition metal activation technology may cause secondary pollution. These factors hinder the widespread application of dithionite technology in organic wastewater treatment.

[0011] However, existing chlorination and SO4 ·- Most advanced oxidation technologies require the addition of active chlorine, such as sodium hypochlorite, to induce the system to generate highly oxidizing free radicals. Summary of the Invention

[0012] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, the object of the present invention is to provide a method for treating dibenzo[a]oxane organic pollutants in water bodies.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] This invention provides a method for treating dibenzo[a]oxa organic pollutants in water, comprising the following steps:

[0015] The wastewater to be treated is electrolyzed and dithionite is added to carry out an oxidation-reduction reaction to obtain purified water; the wastewater to be treated contains sodium chloride and dibenzo[a]benzene organic pollutants.

[0016] In this invention, dithionite is added to water containing dibenzo[a]pyrene organic pollutants via electrolysis using an external power source. Dithionite has the property of hydrolyzing and acidifying water, promoting the generation of active chlorine from the background chlorine in the water during electrolysis. The active chlorine generated by DTN activation produces sulfate free radicals (SO42-) during the reaction. ·- ), chlorine radicals (Cl· / Cl2) ·- The generated free radicals, such as hypochlorite radicals (ClO·) and hydroxyl radicals (·OH), are highly reactive groups. These highly reactive groups have high redox potentials and exhibit strong oxidizing properties, which can break the unsaturated chemical bonds in recalcitrant organic matter, thereby achieving a degradation effect.

[0017] In some embodiments of the present invention, the concentration of dibenzo[a]organic pollutants in the water is 1–20 μmol / L, such as 10–15 μmol / L.

[0018] In some embodiments of the present invention, the molar ratio of the dithionite and the dibenzo[a]pyrene organic pollutant is (10-600):1, such as (50-200):1.

[0019] In some embodiments of the present invention, the concentration of the dithionite is 50–400 μmol / L, such as 100–300 μmol / L, 180–280 μmol / L, etc.

[0020] In some embodiments of the present invention, the current intensity of the redox reaction is 5-100 mA, such as 5-50 mA, 5-30 mA, 8-25 mA, etc.

[0021] In some embodiments of the present invention, the concentration of sodium chloride in the water is 5-100 mM, such as 5-80 mM, 10-50 mM, etc.

[0022] In some embodiments of the present invention, the electrolysis time is at least 0.1 min, such as 0.1 to 60 min, and the electrolysis time is adjusted according to the amount of dibenzo[a]oxane organic pollutants in the water to be treated.

[0023] In some embodiments of the present invention, the redox reaction is carried out under stirring at a rate of 200–1000 r / min, such as 500–1000 r / min.

[0024] In some embodiments of the present invention, the reaction temperature of the redox reaction is 10-50°C, and generally, it can be carried out at room temperature such as 20-40°C (e.g., 25-25°C); the reaction time of the redox reaction is at least 30 min, such as at least 60 min, 60-120 min; the redox reaction time can be adjusted according to the amount of dibenzo[a]-type organic pollutants in the water to be treated or the content of such pollutants in the water.

[0025] In some embodiments of the present invention, the dibenzo-based organic pollutants include carbamazepine and / or oxcarbazepine.

[0026] In some embodiments of the present invention, the dithionite includes salts containing dithionite ions; the dithionite includes at least one of sodium dithionite, potassium dithionite, sodium hyposulfite, and potassium hyposulfite.

[0027] In some embodiments of the present invention, when the wastewater to be treated is coastal water, the coastal water contains sodium chloride, so there is no need to add additional sodium chloride; when the wastewater to be treated is wastewater that does not contain sodium chloride, additional sodium chloride needs to be added.

[0028] The beneficial effects of this invention are:

[0029] The method for treating dibenzo[a] organic pollutants in water bodies according to the present invention is carried out under normal temperature and pressure conditions. The reaction is mild, environmentally friendly, easy to operate, low in cost, and has a good degradation effect on dibenzo[a] organic pollutants in the environment. It has great application potential in the field of environmental pollution control. Attached Figure Description

[0030] Figure 1 This is a graph showing the degradation rate of carbamazepine treated by in-situ electrolysis using background chlorine in conjunction with DTN oxidation in Example 1 of the present invention.

[0031] Figure 2 This is a graph showing the degradation rate of carbamazepine-containing organic wastewater in situ using background chlorine in synergistic DTN degradation at different DTN concentrations in Example 2 of the present invention.

[0032] Figure 3 This is a graph showing the degradation rate of carbamazepine-containing organic wastewater in situ using background chlorine in synergistic DTN degradation under different current intensities in Example 3 of the present invention.

[0033] Figure 4 This is a graph showing the degradation rate of carbamazepine-containing organic wastewater in situ using background chlorine in synergistic DTN degradation at different electrolyte concentrations in Example 4 of the present invention. Detailed Implementation

[0034] The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0035] Example 1

[0036] This embodiment describes the treatment of wastewater containing carbamazepine, and the specific process is as follows:

[0037] Take three opaque reaction vessels (numbered 1 to 3 respectively), add organic wastewater containing 2 μmol / L carbamazepine (simulated wastewater) to each, and add NaCl containing 5 mmol / L (simulated coastal water salinity) to each. The pH value of each reactor is 7.0, the reaction temperature is 30℃, and the three reactors are shaken to ensure uniform reaction.

[0038] An external power source was applied to reaction vessel 1 with a current intensity of 10 mA (EO-Cl). Sodium dithionite solution was added to reaction vessel 2 to a concentration of 100 μmol / L (DTN). An external power source was applied to reaction vessel 3 with a current intensity of 10 mA and sodium dithionite solution to a concentration of 100 μmol / L (EO-Cl / DTN). After 60 minutes, the reaction was essentially complete. The remaining concentration of carbamazepine in the wastewater was measured, and the results are shown in Table 1 below. Figure 1 As shown.

[0039] Table 1

[0040] Reactor number Reactor 1 Reactor 2 Reactor 3 Carbamazepine degradation rate (%) 43.9 0.5 75.5

[0041] From Table 1, Figure 1 It was found that when using external power source electrolysis and sodium dithionite alone, the degradation rates of carbamazepine within 60 minutes were 54.9% and 0.5%, respectively; when using external power source and sodium dithionite in combination, the degradation rate of carbamazepine within 60 minutes was 75.5%. This indicates that dithionite can effectively activate the active chlorine generated by in-situ electrolysis, significantly promoting the oxidation of dibenzo[a]pyrene organic pollutants. It can activate dithionite to generate active groups, enabling effective degradation of carbamazepine. Its treatment effect is significantly better than that of electro-oxidation or dithionite alone.

[0042] Example 2

[0043] This embodiment uses different concentrations of dithionite to treat carbamazepine-containing wastewater. The specific process is as follows:

[0044] Seven opaque reaction vessels (numbered 1-7) were taken, and organic wastewater containing 2 μmol / L carbamazepine was added to each. The pH value of each reactor was 7.0, the reaction temperature was 30℃, and the electrolyte concentration was 5 mmol / L NaCl. An external power supply with a current intensity of 10 mA and sodium dithionite solution were applied to reaction vessel 1 to achieve a concentration of 0 μmol / L; an external power supply with a current intensity of 10 mA and sodium dithionite solution were applied to reaction vessel 2 to achieve a concentration of 50 μmol / L; and an external power supply with a current intensity of 10 mA and sodium dithionite solution were applied to reaction vessel 3 to achieve a concentration of 100 μmol / L. An external power source with a current intensity of 10 mA and sodium dithionite solution were applied to reaction vessel 4 to achieve a concentration of 150 μmol / L. An external power source with a current intensity of 10 mA and sodium dithionite solution were applied to reaction vessel 5 to achieve a concentration of 200 μmol / L. An external power source with a current intensity of 10 mA and sodium dithionite solution were applied to reaction vessel 6 to achieve a concentration of 250 μmol / L. An external power source with a current intensity of 10 mA and sodium dithionite solution were applied to reaction vessel 7 to achieve a concentration of 500 μmol / L. After 60 minutes, the reaction was essentially complete. The residual concentration of carbamazepine in the wastewater was then measured, and the results are shown in Table 2 below. Figure 2 As shown.

[0045] Table 2

[0046]

[0047] From Table 2, Figure 2 It can be seen that, with the increase of dithionite concentration, under the same reaction conditions, the degradation rate of carbamazepine initially increases and then decreases after 60 minutes of reaction. When the dithionite concentration is 250 μmol / L, the degradation rate of carbamazepine reaches a maximum of over 80%.

[0048] Example 3

[0049] This embodiment uses different electrolysis currents to treat carbamazepine-containing wastewater. The specific process is as follows:

[0050] Five opaque reaction vessels (numbered 1-5) were used, and organic wastewater containing 2 μmol / L carbamazepine was added to each. The reaction temperature was 30℃, and the electrolyte concentration was 5 mmol / L NaCl. The five reactors were shaken to ensure uniform reaction. Sodium disulfite solution was simultaneously added to each of the five reaction vessels to a concentration of 250 μmol / L. An external power supply was applied, and the current intensity in the five reactors was adjusted to 5 mA, 10 mA, 15 mA, 20 mA, 30 mA, and 50 mA, respectively, and continued for 60 minutes until the reaction was essentially complete. The remaining concentration of carbamazepine in the wastewater was then measured, and the results are shown in Table 3 below. Figure 3 As shown.

[0051] Table 3

[0052]

[0053] From Table 3, Figure 3 It can be seen that under different reaction current intensities, the degradation rate of carbamazepine increases with the increase of current intensity. Considering both energy consumption and degradation rate, 10mA is taken as the optimal current intensity.

[0054] Example 4

[0055] This embodiment describes the treatment of carbamazepine-containing wastewater at different electrolyte concentrations. The specific process is as follows:

[0056] Five opaque reaction vessels were used, and NaCl solution was added to each vessel to achieve concentrations of 5 mmol / L, 10 mmol / L, 20 mmol / L, 30 mmol / L, and 50 mmol / L, respectively. The reaction temperature was 30℃, and the five reactors were shaken to ensure uniform reaction. An external current of 10 mA and sodium dithionite solution of 250 μmol / L were simultaneously applied to each of the five reaction vessels. The pH values ​​in the five reactors were adjusted to 7.0 using 0.1 mol / L NaOH solution and 0.1 mol / L dilute H₂SO₄, respectively. After 60 minutes, the reaction was essentially complete. The residual concentration of carbamazepine in the wastewater was then measured, and the results are shown in Table 4 below. Figure 4 As shown.

[0057] Table 4

[0058]

[0059] From Table 4, Figure 4 It can be seen that, under different electrolyte concentrations, the degradation rate of carbamazepine generally increases with the increase of the concentration of the electrolyte NaCl.

[0060] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for treating dibenzo[a]oxa organic pollutants in water, characterized in that: Includes the following steps: The wastewater to be treated is added to dithionite for electrolysis to carry out an oxidation-reduction reaction, thereby obtaining purified water; the wastewater to be treated contains sodium chloride and dibenzo[a]pyroxene organic pollutants; the current intensity of the oxidation-reduction reaction is 5-100 mA; the concentration of sodium chloride in the wastewater to be treated is 5-100 mM.

2. The method for treating dibenzo[a]oxa organic pollutants in water according to claim 1, characterized in that: The concentration of dibenzo[a]oxa organic pollutants in the wastewater to be treated is 1–20 μmol / L.

3. The method for treating dibenzo[a]oxa organic pollutants in water according to claim 1, characterized in that: The molar ratio of dithionite to dibenzo[a]pyrene organic pollutant is (10–600):

1.

4. The method for treating dibenzo[a]oxa organic pollutants in water according to claim 1, characterized in that: The current intensity of the redox reaction is 5–50 mA.

5. The method for treating dibenzo[a]oxa organic pollutants in water according to claim 1, characterized in that: The concentration of sodium chloride in the wastewater to be treated is 5–80 mM.

6. The method for treating dibenzo[a]oxa organic pollutants in water according to claim 1, characterized in that: The electrolysis time is at least 0.1 min.

7. The method for treating dibenzo[a]oxa organic pollutants in water according to claim 1, characterized in that: The redox reaction is carried out under stirring at a rate of 200–1000 r / min; and / or the reaction temperature is 10–50 °C.

8. The method for treating dibenzo[a]oxa organic pollutants in water according to claim 1, characterized in that: The dibenzo[a]organic pollutants include carbamazepine and / or oxcarbazepine.

9. The method for treating dibenzo[a]oxa organic pollutants in water according to claim 1, characterized in that: The dithionite includes salts containing dithionite ions; the dithionite includes at least one of sodium dithionite, potassium dithionite, sodium hyposulfite, and potassium hyposulfite.

10. The method for treating dibenzo[a]oxa organic pollutants in water according to claim 1, characterized in that: When the wastewater to be treated is coastal water, no additional sodium chloride is required; when the wastewater to be treated is wastewater that does not contain sodium chloride, additional sodium chloride needs to be added.

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