Method for treating methyl orange wastewater by dual-wavelength ultraviolet and ozone micro-nano bubble cooperation

Abstract

The application discloses a kind of dual-wavelength ultraviolet light synergistic ozone micro-nano bubble treatment methyl orange wastewater method, belong to wastewater treatment technical field.The method is first to the micro-nano bubble generator is carried out organic solvent ultrasonic cleaning, deionized water flushing and drying pretreatment, then preparation ozone micro-nano bubble water, finally under the condition of stirring ozone micro-nano bubble water is mixed with methyl orange solution, through UV-222 and UV-254 dual-wavelength ultraviolet lamp irradiation realizes methyl orange degradation.The application combines the synergistic effect of ozone micro-nano bubble and dual-wavelength ultraviolet light, strengthens hydroxyl radical generation and organic matter photolysis, improves methyl orange decolorization and mineralization efficiency, can also photolyze debromination to avoid bromate byproduct, whole process does not need to add reagent, no sludge is generated, equipment system is simple and easy to control, applicable to the treatment of methyl orange azo dye wastewater, with good engineering application value.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment and relates to a method for treating methyl orange wastewater by combining dual-wavelength ultraviolet light with ozone micro-nano bubbles. Background Technology

[0002] Methyl orange, a typical azo dye, is widely used in industrial production such as textiles, printing and dyeing, and papermaking. Traditional treatment methods, such as biochemical treatment, coagulation sedimentation, adsorption, and Fenton process, have drawbacks such as low treatment efficiency, large amounts of additives required, secondary pollution, and high operating costs. Biochemical treatment is difficult to degrade methyl orange and other recalcitrant organic pollutants; coagulation treatment produces a large amount of chemical sludge; adsorption has limited adsorbent capacity and is difficult to regenerate; and Fenton process produces a large amount of iron sludge and has high energy consumption.

[0003] Ozone mass transfer efficiency is a key factor affecting oxidation effectiveness. Ozone micro / nanobubbles, due to their small size, large specific surface area, high interfacial zeta potential, and long residence time, show great promise for applications in wastewater treatment. Meanwhile, ultraviolet (UV) synergistic ozone micro / nanobubble technology has attracted significant attention because it can more efficiently generate highly oxidizing hydroxyl radicals (·OH) and promote ozone decomposition, reducing ozone leakage.

[0004] UV-222 far-ultraviolet light has high photon energy, and organic pollutants exhibit a higher molar absorptivity at 222 nm wavelength. This allows for efficient direct photolysis of micro-pollutants and the efficient generation of active species through the photolysis of oxidant precursors. However, components in the water matrix have a strong absorption capacity for 222 nm ultraviolet light, potentially competing with pollutants and oxidant precursors for ultraviolet photons. In contrast, UV-254 ultraviolet light has a longer penetration distance, and its molar absorptivity for bromide ions and dissolved organic matter (DOM) in dyeing and printing wastewater is significantly lower than that at 222 nm. It is less affected by the light shielding effect of such matrices and can penetrate to deeper water layers to achieve uniform irradiation of pollutants. Therefore, further research is needed on ultraviolet light combined with ozone micro / nanobubble technology.

[0005] In the prior art, patent CN 117735700 A discloses a UV-enhanced ozone micro-nano bubble method for efficiently removing water. Methods for simultaneously weakening the bromate formation potential of organic pollutants, involving ultraviolet light intensities of 0.1-100 mW / cm². 2 However, this technical solution does not address the wavelength of ultraviolet light, nor does it mention the combined use of UV-222 and UV-254.

[0006] Patent CN 121342283 A discloses a process for treating advanced oxidative dyeing and printing wastewater by continuously introducing ozone generated by an ozone generator into a reactor under ultraviolet light irradiation. The wavelength of the irradiation is 185 nm to 285 nm, and the intensity is 90 μW / cm². 2 ~200 μW / cm 2 However, this technical solution does not mention the combined use of UV-222 and UV-254, and it also uses an additional oxidant, which is prone to causing secondary pollution and is not economical. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for treating methyl orange wastewater using dual-wavelength ultraviolet light synergistically combined with ozone micro-nano bubbles. Targeting the issues of high color intensity, poor biodegradability, low degradation efficiency, and easy secondary pollution associated with traditional treatment processes for methyl orange azo dye wastewater, this method employs a dual-wavelength ultraviolet light combination of UV-222 and UV-254 to construct a highly efficient activation and deep-penetration synergistic irradiation system. This overcomes the technical shortcomings of existing single-wavelength ultraviolet light synergistic ozone technologies, such as the difficulty in simultaneously achieving adequate water penetration and interfacial oxidation capacity, and low ozone mass transfer efficiency. Simultaneously, it utilizes ultraviolet light to break down carbon... Bromine bond (C The process achieves debromination by Br, avoids the formation of bromate byproducts, significantly improves the treatment efficiency and operational safety of dyeing and printing wastewater, and has no secondary pollution, is environmentally friendly and energy-saving, thus having important engineering application value.

[0008] This invention provides a method for treating methyl orange using dual-wavelength ultraviolet light in conjunction with ozone micro-nano bubbles, the specific steps of which are as follows: (1) Preparation of ozone micro-nano bubbles: Start the micro-nano bubble generator to generate micro-nano bubbles, input oxygen into the ozone generator to generate ozone, input ozone into the micro-nano bubble generator to obtain ozone micro-nano bubbles; (2) Degradation of methyl orange solution: Ozone micro-nano bubbles are introduced into the solution containing methyl orange, and UV-222 ultraviolet light and UV-254 ultraviolet light are set above the solution for irradiation. Stirring can achieve the treatment of methyl orange in the solution.

[0009] In one embodiment of the present invention, the ozone micro-nano bubble particle size in step (1) is 100-300 nm.

[0010] In one embodiment of the present invention, the concentration of ozone in the solution through which ozone micro-nano bubbles are introduced in step (2) is 10-30 mg / L.

[0011] In one embodiment of the present invention, the concentration of ozone in the solution through which ozone micro-nano bubbles are introduced in step (2) is 12-18 mg / L.

[0012] In one embodiment of the present invention, the pH of the solution containing methyl orange in step (2) is 3.0-11.0.

[0013] In one embodiment of the present invention, the concentration of methyl orange in the solution containing methyl orange in step (2) is less than 100 mg / L. In one embodiment of the present invention, the UV-222 ultraviolet light in step (2) can be emitted using a KrCl* krypton chloride excimer ultraviolet lamp with a wavelength of 222nm and a power of 15W.

[0014] In one embodiment of the present invention, the UV-254 ultraviolet light in step (2) can be emitted using a low-pressure mercury ultraviolet lamp with a power of 15W.

[0015] In one embodiment of the present invention, the UV-222 ultraviolet irradiation dose rate in step (2) is 0.5~0.7mW / cm². 2 .

[0016] In one embodiment of the present invention, the UV-254 ultraviolet irradiation dose rate in step (2) is 0.3~0.5mW / cm². 2 .

[0017] In one embodiment of the present invention, the UV-222 ultraviolet irradiation dose rate in step (2) is 0.6 mW / cm². 2 The UV-254 ultraviolet light irradiation dose rate is 0.48 mW / cm². 2 .

[0018] In one embodiment of the present invention, the stirring speed in step (2) is 50-100 r / min.

[0019] In one embodiment of the present invention, the ozone micro-nano bubbles generated in step (1) can be first introduced into water to form ozone micro-nano bubble water, and then the ozone micro-nano bubble water is mixed with a solution containing methyl orange, and UV-222 and UV-254 ultraviolet light are set to irradiate the mixed solution to treat the methyl orange.

[0020] In one embodiment of the present invention, the concentration of ozone in the ozone micro-nano bubble water is 10-30 mg / L.

[0021] Beneficial effects High degradation efficiency and significant synergistic effect: This invention combines ozone micro-nano bubbles with the complementary advantages of UV-222 and UV-254 dual-wavelength ultraviolet light, which enhances the generation of hydroxyl radicals and the photolysis of organic matter, and greatly improves the decolorization rate and mineralization depth of methyl orange.

[0022] Safe, environmentally friendly, and free of secondary pollution: Dual-wavelength ultraviolet light can break down the chain and debrominate to avoid bromate byproducts. No reagents need to be added throughout the process, no sludge is generated, and ozone emissions are reduced. The treatment process is green and environmentally friendly.

[0023] The process is easy to control and highly practical: The equipment system of this invention is simple, the operating parameters are controllable and can be intelligently adjusted, it has a wide pH range adaptability to wastewater, and it is easy to integrate into engineering and apply on a large scale. Attached Figure Description

[0024] Figure 1 The images show the decolorization effects of methyl orange in Examples 1, 1, 2, and 3.

[0025] Figure 2 The images show the mineralization effects of methyl orange in Examples 1, 1, 2, and 3.

[0026] Figure 3 The images show the decolorization effects of methyl orange on comparative examples 1, 4, 5, 6, and 7.

[0027] Figure 4 The images show the mineralization effects of methyl orange in Comparative Examples 1, 4, 5, 6, and 7. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the embodiments.

[0029] System operation method: The oxygen pipe of the oxygen cylinder is connected to the air inlet of the ozone generator, the ozone outlet pipe is connected to the air inlet of the micro-nano bubble generator, and the bubble water outlet pipe and water inlet pipe are connected to the reaction vessel, so that the reaction solution circulates between the micro-nano bubble generator and the reaction vessel; at the same time, the ultraviolet lamp tube (UV-222, UV-254) above the liquid surface of the reaction vessel and the constant temperature water bath are turned on.

[0030] TOC Testing Method: The Total Organic Carbon (TOC) analyzer is a specialized instrument for measuring the total organic carbon content in samples. Designed in accordance with relevant standards such as HJ 501-2009 and ISO 8245, it boasts high detection accuracy and good stability. This equipment is used to test the total organic carbon content in industrial wastewater samples. It quantifies the TOC value by measuring the concentration of carbon dioxide after the conversion of organic carbon in the sample, thereby assessing the degree of organic pollution or the level of organic matter content in the sample. The instrument automatically calculates and outputs the TOC value of the sample via a digital display.

[0031] The main technical parameters of the total organic carbon analyzer include a measurement range of 0.01-5000 mg / L, a detection limit of ≤0.01 mg / L, an analysis time of ≤3 min / sample, a sample injection volume of 10 μL-2000 μL, an adjustable combustion furnace temperature range of 680℃-1000℃, an instrument weight of approximately 35 kg, and dimensions of 450×350×500 mm.

[0032] Colorimetric testing method: The UV-2600 ultraviolet-visible spectrophotometer is a specialized instrument for ultraviolet-visible spectral analysis, accurately used for the detection of colorimetric properties of methyl orange solutions. Designed in accordance with relevant standards such as GB / T 26798 and ISO7886, it employs an advanced dual-beam optical system, exhibiting high wavelength accuracy, photometric precision, and good stability. The concentration of the methyl orange solution is determined by measuring its absorption of visible light at a specific wavelength. During the detection process, the methyl orange solution sample is first transferred to a cuvette and placed in the instrument's sample cell. By setting parameters such as the detection wavelength (464nm) and scanning range, and combining this with a pre-plotted methyl orange concentration-absorbance standard curve, the sample concentration is calculated, and thus its colorimetric value is obtained.

[0033] The main technical parameters of the UV-Vis spectrophotometer include a wavelength range of 200-1400 nm, wavelength accuracy of ±0.8 nm, wavelength repeatability of 0.3 nm, photometric accuracy of ±0.004 Abs (0-0.5 Abs), photometric range of 0-200%T, instrument weight of approximately 20 kg, and dimensions of 545×245×260 mm.

[0034] In the examples and comparative examples, KrCl* excimer UV lamps were used with a wavelength of 222 nm and specifications of 9W (0.36 mW / cm²). 2 ), 15W (0.60 mW / cm) 2 ), 21W (0.84 mW / cm) 2 Low-pressure mercury ultraviolet lamps were used, with a wavelength of 254nm and specifications of 9W (0.288 mW / cm²). 2 ), 15W (0.48 mW / cm) 2 ), 21W (0.672 mW / cm) 2 ).

[0035] Example 1 A method for treating methyl orange wastewater using dual-wavelength ultraviolet light synergistically combined with ozone micro-nano bubbles, comprising the following steps: (1) The micro-nano bubble generator was ultrasonically cleaned with ethanol for 30 min, rinsed with deionized water 3 times, and dried at 80℃ to obtain the cleaned micro-nano bubble generator.

[0036] (2) Inject 1 L of deionized water into the reaction vessel at a temperature of 25°C, then place the reaction vessel in a constant temperature water bath at 25°C; start the micro-nano bubble generator to stably generate micro-nano bubble water, and wait for the bubble particle size to stabilize at 100-300 nm; the bubble concentration ≥ 10 8 Oxygen with a flow rate of 300 mL / min and a purity greater than 99% is fed into the ozone generator via a flow meter; after the generated ozone flow rate stabilizes at 150 mL / min, it is fed into the micro-nano bubble generator, a sample is taken and the ozone concentration in the water is determined by the indigo method to obtain ozone micro-nano bubble water; (3) Under stirring conditions of 60 r / min, 20 mg of methyl orange was first dissolved in deionized water (0.2 L), stirred evenly, and then ozone micro-nano bubble water (0.8 L) was poured in. The total reaction solution was kept to 1 L, the final concentration of methyl orange was 20 mg / L, and the final concentration of ozone in the water was 16 mg / L. 5 mL samples were taken at 0, 30, 60, 90, 120, 150, and 180 s, in triplicate, and the absorbance was detected by UV-2600 to analyze the degree of decolorization of methyl orange. 15 mL samples were taken at 0, 20, 40, 60, and 120 min, in triplicate, and the total organic carbon (TOC) was detected by a total organic carbon analyzer to analyze the degree of mineralization of methyl orange.

[0037] Comparative Example 1 Referring to Example 1, the difference from Example 1 is that in step (3), UV-222 (KrCl* excimer ultraviolet lamp, 15W) and UV-254 (low-pressure mercury ultraviolet lamp, 15W) were added above the surface of the reaction solution. The power ratio of UV-222 to UV-254 was 5:5, the total power was maintained at 30W, and the ultraviolet irradiation dose rate was 1.08 mW / cm. 2 .

[0038] Comparative Example 2 Referring to Comparative Example 1, the difference from Comparative Example 1 is that in step (2), the pH value of the deionized water is adjusted to 3.

[0039] Comparative Example 3 Referring to Comparative Example 1, the difference from Comparative Example 1 is that in step (2), the pH value of the deionized water is adjusted to 11.

[0040] The chromogenic group of methyl orange has an absorbance peak at 464 nm. The experiment uses the change of the peak at this wavelength to correspond to the change of methyl orange concentration, which actually refers to the change of methyl orange color.

[0041] from Figure 1It can be seen that: In Example 1, the decolorization efficiency of O3-MNBs alone for methyl orange is generally low, with methyl orange concentrations of 14.883 mg / L and 1.25 mg / L at 30 s and 180 s, respectively; In Comparative Example 1, the O3-MNBs-UV system reached a methyl orange concentration of 0.847 mg / L at 150 s, showing a higher decolorization efficiency; In Comparative Example 2, the O3-MNBs-UV system, due to being in an acidic environment, inhibited ozone self-decomposition, prolonged half-life, stabilized ozone solubility in water, and greatly enhanced direct oxidation by ozone, thus resulting in a higher decolorization efficiency and better effect for methyl orange; Similarly, In Comparative Example 3, the O3-MNBs-UV system, due to being in an alkaline environment, experienced an explosive chain reaction of ozone self-decomposition, generating a large amount of more oxidizing ·OH, which not only improved the decolorization efficiency of methyl orange but also enhanced the degree of decolorization.

[0042] from Figure 2 It can be seen that: in Example 1, the TOC of the standalone O3-MNBs system was 3.841 mg / L and 3.461 mg / L at 20 min and 120 min, respectively. Due to the direct photolysis of dual-wavelength ultraviolet light and the increase of ·OH, the mineralization rate and degree of the O3-MNBs-UV system in Comparative Example 1 were significantly improved, with TOC of 2.687 mg / L and 2.164 mg / L at 20 min and 120 min, respectively. The O3-MNBs-UV system in Comparative Example 2 under acidic conditions performed poorly, with TOC of 6.653 mg / L and 5.411 mg / L at 20 min and 120 min, respectively, because ozone decomposition was inhibited under acidic conditions, resulting in lower ·OH production and insufficient mineralization capacity of ozone itself. The O3-MNBs-UV system in Comparative Example 3 under alkaline conditions performed better, with TOC of 5.824 mg / L and 1.244 mg / L at 20 min and 1.244 mg / L, respectively. The concentration of mg / L indicates that the mineralization initiation rate is relatively slow at 20 min because it takes time for ozone to decompose and generate ·OH. At 40 min, the degree of mineralization has significantly exceeded that of other systems because the ·OH generated by ozone in an alkaline environment has a higher oxidation-reduction potential and stronger mineralization ability.

[0043] Comparative Example 4 Referring to Example 1, the difference from Example 1 is that in step (3), two UV-222 lamps (15W) were added above the surface of the reaction solution, with a total power of 30W and an ultraviolet irradiation dose rate of 1.2 mW / cm². 2 .

[0044] Comparative Example 5 Referring to Example 1, the difference from Example 1 is that in step (3), two UV-254 lamps (15W) were added above the surface of the reaction solution, with a total power of 30W and an ultraviolet irradiation dose rate of 0.96 mW / cm. 2 .

[0045] Comparative Example 6 Referring to Example 1, the difference from Example 1 is that in step (3), UV-222 (9W) and UV-254 (21W) lamps were added above the surface of the reaction solution, with a power ratio of 3:7, a total power of 30W, and an ultraviolet irradiation dose rate of 1.032 mW / cm². 2 .

[0046] Comparative Example 7 Referring to Example 1, the difference from Example 1 is that in step (3), UV-222 (21W) and UV-254 (9W) lamps were added above the surface of the reaction solution, with a power ratio of 7:3, a total power of 30W, and an ultraviolet irradiation dose rate of 1.128 mW / cm². 2 .

[0047] Table 1. Methyl orange concentration (mg / L)

[0048] from Figure 3 It can be seen that: in Example 1, the simple O3-MNBs process has limited decolorization efficiency for pollutants and the reaction slows down in the later stages, with a concentration of 1.250 mg / L at 180 s; in Comparative Example 1, the O3-MNBs-UV (5:5) system, due to the introduction of a specific ratio of 222nm and 254nm dual-wavelength ultraviolet light, has a faster decolorization speed and a deeper degree (concentration of 0.827 mg / L at 180 s), and its synergistic effect is the most significant. In contrast, the O3-MNBs-UV-222 system in Comparative Example 4 mainly relies on the strong direct photolysis effect of 222nm ultraviolet light on organic matter, resulting in faster decolorization in the early stages of the reaction, but weak penetration ability and limited effect in the later stages; the O3-MNBs-UV-254 system in Comparative Example 5 relies on the efficient catalytic decomposition of ozone to produce ·OH by 254nm ultraviolet light, which has strong indirect oxidation ability, so its decolorization efficiency and depth are better than that of simple O3-MNBs. It is worth noting that the O3-MNBs-UV (3:7) system in Comparative Example 6 and the O3-MNBs-UV (7:3) system in Comparative Example 7 further revealed the influence of power ratio: UV-222 with shorter wavelength has an advantage in the early stage (strong photon energy, direct photolysis), while UV-254 with longer wavelength is more conducive to deep decolorization in the later stage (wide range of action, decomposition of O3 to produce ·OH). However, the overall effect of both is not as good as the optimal ratio of 5:5, which achieves the best synergy between direct photolysis and free radical oxidation.

[0049] Table 2 Total Organic Carbon Content (TOC, mg / L)

[0050] from Figure 4 It can be seen that the simple O3-MNBs process in Example 1 has limited TOC removal capacity. After 120 min, the TOC concentration is still as high as 3.461 mg / L, indicating that its mineralization of organic matter is incomplete. The O3-MNBs-UV (5:5) system in Comparative Example 1 showed the strongest organic matter mineralization capacity, with the lowest TOC concentration (2.164 mg / L) at 120 min. This is due to the efficient synergy of dual-wavelength ultraviolet light on ozone decomposition and direct chain scission of organic matter, which promotes the complete conversion of pollutants into CO2 and H2O. Although the O3-MNBs-UV-222 system in Comparative Example 4 has a certain mineralization effect, its mechanism focuses more on direct photolysis and is insufficient for deep oxidation of complex organic molecules, so the TOC removal rate is the lowest (120 min, 3.205 mg / L). The O3-MNBs-UV-254 system in Comparative Example 5 has excellent performance in mineralization degree due to the characteristic of generating strong oxidizing ·OH with high efficiency under 254nm ultraviolet light (120 min, 2.983 mg / L), which is significantly better than O3-MNBs alone. Data from the O3-MNBs-UV (3:7) system in Comparative Example 6 and the O3-MNBs-UV (7:3) system in Comparative Example 7 confirm the dominant role of UV-254 in the mineralization process: the mineralization effect of the O3-MNBs-UV (3:7) system, with a higher proportion of 254nm UV light (2.751 mg / L), is close to the optimal 5:5 system, while the effect of the O3-MNBs-UV (7:3) system, with a higher proportion of 222nm UV light (3.110 mg / L), is relatively weaker. In summary, the O3-MNBs-UV (5:5) system achieves rapid decolorization while also achieving the most thorough organic mineralization, demonstrating its comprehensive advantages as a deep processing technology.

[0051] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for treating methyl orange using dual-wavelength ultraviolet light synergistically with ozone micro / nanobubbles, characterized in that, The specific steps are as follows: (1) Preparation of ozone micro-nano bubbles: Start the micro-nano bubble generator to generate micro-nano bubbles, input oxygen into the ozone generator to generate ozone, input ozone into the micro-nano bubble generator to obtain ozone micro-nano bubbles; (2) Degradation of methyl orange solution: Ozone micro-nano bubbles are introduced into a solution containing methyl orange, and UV-222 ultraviolet light and UV-254 ultraviolet light are placed above the solution for irradiation. Stirring can achieve the treatment of methyl orange in the solution. The ozone concentration in the solution through which ozone micro-nano bubbles are introduced is 10-30 mg / L; the UV-222 ultraviolet irradiation dose rate is 0.5~0.7 mW / cm². 2 The UV-254 ultraviolet light irradiation dose rate is 0.3~0.5 mW / cm². 2 .

2. The method according to claim 1, characterized in that, In step (1), the ozone micro-nano bubble particle size is 100-300 nm.

3. The method according to claim 1, characterized in that, In step (2), the concentration of ozone in the solution through which ozone micro-nano bubbles are introduced is 12-18 mg / L.

4. The method according to claim 1, characterized in that, The pH of the solution containing methyl orange in step (2) is 3.0-11.

0.

5. The method according to claim 1, characterized in that, In step (2), the concentration of methyl orange in the solution containing methyl orange is less than 100 mg / L.

6. The method according to claim 1, characterized in that, In step (2), the UV-222 ultraviolet light is emitted using a KrCl* krypton chloride excimer ultraviolet lamp with a wavelength of 222nm and a power of 15W.

7. The method according to claim 1, characterized in that, In step (2), UV-254 ultraviolet light is emitted using a low-pressure mercury ultraviolet lamp with a power of 15W.

8. The method according to claim 1, characterized in that, The stirring speed in step (2) is 50-100 r / min.

9. The method according to claim 1, characterized in that, The ozone micro-nano bubbles generated in step (1) are first introduced into water to form ozone micro-nano bubble water. Then, the ozone micro-nano bubble water is mixed with a solution containing methyl orange, and UV-222 and UV-254 ultraviolet light are used to treat the methyl orange in the mixed solution.

10. The method according to claim 9, characterized in that, The ozone concentration in ozone micro-nano bubble water is 10-30 mg / L.

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