Concentrated waste acid purification process and device based on ultraviolet catalytic oxidation

Abstract

The invention discloses a concentrated waste acid purification process and device based on ultraviolet catalytic oxidation, and belongs to the technical field of industrial waste acid recycling and advanced oxidation water treatment. The method specifically comprises the following steps: introducing air or oxygen into the waste liquid for aeration; under irradiation of 185 nm ultraviolet light, ozone (O3) is generated in situ; meanwhile, adding hydrogen peroxide (H2O2), and activating under the irradiation of 254 nm ultraviolet light to generate hydroxyl radicals (. OH); organic polycarboxylic acid is added as a micro-zone pH buffering agent. According to the method disclosed by the invention, the pH 1t; the method has the advantages that 1, efficient deep oxidation without adding a metal catalyst and adjusting pH in a strong acid environment is realized, the treated waste acid is high in purity and can be directly recycled, and the method is high in treatment efficiency, low in operation cost and free of secondary pollution;

Description

Technical Field

[0001] This invention relates to the field of industrial waste acid resource utilization and advanced oxidation water treatment technology, specifically a concentrated waste acid purification process and device based on ultraviolet photocatalytic oxidation. Background Technology

[0002] Industrial waste acids (such as sulfuric acid from acetylene purification and semiconductor etching waste acids) often contain high concentrations of recalcitrant organic matter, making direct disposal costly. Traditional UV / hydrogen peroxide processes suffer from low activation efficiency of hydrogen peroxide under strong acid conditions (pH < 1), resulting in poor treatment outcomes. While UV / Fenton processes can effectively degrade organic matter, they require the introduction of Fe... 2+ Using metal ions as catalysts severely impacts the purity and economic value of subsequent acid recovery. If an external ozone generator is used in conjunction with hydrogen peroxide, there are issues such as high equipment investment and operating costs, and safety and disposal risks associated with ozone exhaust. Although some improved technologies exist, such as the solution disclosed in existing patent (CN113582336A), this approach still relies on high doses of H2O2 or pH adjustment, which not only increases operating costs but may also generate secondary pollution.

[0003] In summary, existing technologies cannot simultaneously meet the three key requirements of high efficiency, low cost, and no secondary pollution.

[0004] Therefore, it is necessary to provide a concentrated waste acid purification process and apparatus based on ultraviolet photocatalytic oxidation to solve the problems mentioned in the background art. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides the following technical solution: A concentrated waste acid purification process and apparatus based on ultraviolet photocatalytic oxidation, characterized by comprising the following steps: Step 1 185nm UV / H2O2 process

[0006] S11. Aeration is performed by introducing oxygen-containing gas into the waste acid to be treated. S12. The waste acid is irradiated with ultraviolet light with a wavelength of 185 nm, so that the oxygen-containing gas generates ozone (O3) in situ under the action of ultraviolet light. S13. Add hydrogen peroxide (H2O2) to the waste acid and irradiate it with ultraviolet light with a wavelength of 254 nm to activate the hydrogen peroxide and generate hydroxyl radicals (·OH). The second step is the 254nm UV / H2O2 process. S21. Hydrogen peroxide (H2O2) and organic polycarboxylic acids are added to the waste acid after step S13. The organic polycarboxylic acids act as micro-zone pH buffers to promote the generation of hydroxyl radicals (·OH). S22. The waste acid is irradiated with ultraviolet light at a wavelength of 254 nm. Without adjusting the pH or adding a metal catalyst, organic pollutants are degraded synergistically through direct oxidation by O3 and oxidation by hydroxyl radicals (·OH).

[0007] Preferably, the irradiation intensity of the 185 nm ultraviolet light is 5–20 mW / cm². 2 The intensity of the 254 nm ultraviolet light irradiation is 20–40 mW / cm². 2 The reaction time is 30-60 minutes.

[0008] Preferably, the oxygen-containing gas is air or oxygen, and the gas flow rate is 0.1–2 L / min·L.

[0009] Preferably, the organic polycarboxylic acid is at least one of citric acid, oxalic acid, and tartaric acid.

[0010] Preferably, the concentration of the organic polycarboxylic acid is 0.01–0.1 wt%.

[0011] Preferably, the amount of hydrogen peroxide (H2O2) added is determined by the control system through segmented addition after detecting the TOC and UVT indicators of the influent.

[0012] The specific calculation formula is as follows: ; Q H2O2 This represents the required oxidant dosage (mg / L); TOC in TOC (mg / L) in the influent representing waste acid; TOC out This represents the desired TOC (mg / L) of the waste acid effluent; M H2O2 =34 g / mol; M TOC =12g / mol; The default value for the oxidation efficiency coefficient is between 0.5 and 0.9. It can be verified by measuring the UVT value of the waste acid. When UVT ≥ 80% is high, 0.5 can be selected as the coefficient. When UVT ≤ 50% is low, 0.9 can be selected as the coefficient. When UVT is between the two, a coefficient between 0.5 and 0.9 can be selected. The default safety factor is 1-1.5.

[0013] Preferably, the waste acid is waste hydrochloric acid, waste sulfuric acid, or a mixed acid, with a TOC concentration of 100–5000 mg / L and a pH < 1.

[0014] A concentrated waste acid purification device based on ultraviolet photocatalytic oxidation, characterized in that it comprises: The reactor body is a sealed cavity resistant to strong acid corrosion; The ultraviolet light source unit includes at least one set of ultraviolet lamps emitting a wavelength of 185nm and at least one set of ultraviolet lamps emitting a wavelength of 254nm; A gas distribution unit is located at the bottom of the reactor body and is used to introduce oxygen-containing gas into the waste acid; The reagent dosing unit includes a hydrogen peroxide storage tank and an organic polycarboxylic acid storage tank connected to the reactor, and is equipped with a metering pump; Preferably, the system also includes a control system connected to the online water quality monitoring instrument and the reagent dosing unit, wherein the control system is configured to control the amount of hydrogen peroxide added based on the monitored TOC and UVT data.

[0015] Preferably, the inner wall of the reactor body is lined with PTFE, PFA or quartz material.

[0016] Preferably, the ultraviolet lamp is a low-pressure mercury lamp, and the 185nm ultraviolet lamp can emit 185nm and 254nm ultraviolet light simultaneously. The transmittance of the outer quartz sleeve is ≥ 90% at a wavelength of 185nm and ≥ 95% at a wavelength of 254nm.

[0017] Preferably, the online water quality monitoring instrument includes at least an online TOC analyzer and a UV254 sensor.

[0018] Compared with the prior art, the present invention provides a concentrated waste acid purification process and device based on ultraviolet photocatalytic oxidation, which has the following beneficial effects: (1) Achieved efficient deep removal of organic matter under strong acid environment: This invention creatively couples two advanced oxidation pathways: ozone (O3) generated in situ by 185nm ultraviolet light and hydrogen peroxide (H2O2) activated by 254nm ultraviolet light to generate hydroxyl radicals (·OH), forming a "synergistic effect of direct oxidation and free radical oxidation" in concentrated waste acid with pH<1.

[0019] (2) It ensures the purity of the regenerated acid and prevents secondary pollution: the entire process does not require pH adjustment and no Na is added. + Fe 2+ Impurities are eliminated, ensuring the purity of the purified waste acid, achieving efficient degradation of waste acid, and providing clean raw materials for subsequent acid recovery.

[0020] (3) It leverages the unique synergistic effect of two oxidants in a strong acid medium: Under strong acidic conditions (pH<1), through the synergistic effect of two oxidants, O3 rapidly degrades easily oxidizable substances, and hydroxyl radicals (·OH) treat stubborn pollutants, thereby increasing the total oxidation efficiency by more than 30%.

[0021] (4) An intelligent oxidant precision dosing and cost control system was established: Based on the pollutant oxidation equivalent, a dynamic calculation model of H2O2 theoretical demand was established and the oxidant dosage was adjusted in combination with the actual on-site operating conditions. Compared with the traditional reagent dosing method, the reagent dosage can be reduced by more than 15%, effectively reducing the operating cost.

[0022] (5) It provides a highly integrated and safe and reliable integrated equipment solution: the 185 / 254 nm dual-wavelength UV lamp can be integrated into one design, and since ozone (O3) is generated in situ, there is no risk of ozone tail gas leakage, no tail gas treatment unit is required, and the complexity of the system is reduced by avoiding the need for external ozone equipment. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that terms such as "upper", "lower", "left", "right", and "middle" used in this specification are only for clarity of description and are not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of this application.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0027] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0028] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0029] As used herein, the term “at least one of…” is intended to be synonymous with “one or more of…”. For example, “at least one of A, B, and C” explicitly includes only A, only B, only C, and combinations thereof.

[0030] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than about 4.5," which should be interpreted to include all the values ​​and ranges described above. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0031] Because ozone (O3) can be generated in situ and continuously under oxygen-containing atmospheres (such as aeration), an external ozone generator is not required. The corresponding reaction equation is as follows:

[0032] ; Considering that a strongly acidic environment is conducive to the stable existence of ozone (O3) and that direct oxidation is the main process under these conditions, it is particularly suitable for treating substances containing specific functional groups (such as benzene rings, etc.). Ozone (O3) has a standard oxidation potential of 2.07 V (pH independent) and can directly oxidize most organic compounds (such as phenols, amines, and unsaturated bonds). Unlike hydroxyl radicals (·OH), ozone (O3) oxidation is selective, but it is more stable in strong acids.

[0033] Under strongly acidic conditions (pH < 2): hydrogen peroxide (H2O2) is protonated to... The reactivity decreases. The reaction rate between ozone (O3) and hydrogen peroxide (H2O2) decreases significantly. Literature reports that the reaction rate at pH=2 is 1–2 orders of magnitude lower than at pH=7. Therefore, in strong acids, ozone (O3) and hydrogen peroxide (H2O2) do not react significantly; they can coexist and each play its role. The corresponding reaction equations are as follows: (High selectivity) (Non-selective, broad-spectrum) In strong acid waste liquid, O3 and H2O2 / UV can work synergistically rather than antagonistically to form a dual pathway of "direct oxidation + free radical oxidation", thereby improving the overall degradation efficiency.

[0034] Example 1 Combination Figure 1 This embodiment provides a concentrated waste acid purification process and apparatus based on ultraviolet photocatalytic oxidation, specifically including: The sample was taken from synthetic waste acid from a chemical plant. Testing showed TOC = 500 mg / L and UVT of the raw water = 90%. [The following appears to be a separate, unrelated sentence:] [Setting...] =0.5 and =1, calculation shows that the hydrogen peroxide (H2O2) dosage is approximately 2575.7 mg / L (calculated at a concentration of 27.5%). The actual operating process parameters are: Step 1 185nm UV / H2O2 process

[0035] The gas flow rate was controlled at 0.5 L / min·L, and the ultraviolet light intensity was 10 mW / cm². 2 The reaction time was 30 minutes, and 1545.4 mg / L of hydrogen peroxide (H2O2) was added.

[0036] The second step is the 254nm UV / H2O2 process. Oxalic acid was added at a dosage of 0.05 wt%, with an ultraviolet light intensity of 25 mW / cm². 2 The reaction time was 30 minutes, and 1030.3 mg / L of hydrogen peroxide (H2O2) was added.

[0037] After the above two-stage oxidation treatment, the TOC of the waste acid was reduced to 8.7 mg / L, and the treatment effect met the company's subsequent process or emission requirements.

[0038] Comparative Example 1A In comparison, the other treatment conditions were the same as in Example 1, and the same waste acid was treated. The difference was that no oxalic acid was added during the 254nm UV / H2O2 process, while the other conditions were exactly the same as in Example 1.

[0039] After treatment, the TOC of the waste acid was 21.8 mg / L, which failed to meet the company's requirements.

[0040] Comparative Example 1B In comparison, the other treatment conditions were the same as in Example 1, and the same waste acid was treated. The difference was that only the 185nm UV / H2O2 process was used, the entire reaction lasted 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0041] After treatment, the TOC of the waste acid was 117.4 mg / L, which failed to meet the company's requirements.

[0042] Comparative Example 1C In comparison, the other treatment conditions were the same as in Example 1, and the same waste acid was treated. The difference was that only the 254nm UV / H2O2 process was used, the entire reaction lasted 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0043] After treatment, the TOC of the waste acid was 163.2 mg / L, which failed to meet the company's requirements.

[0044] Comparative Example 1D In contrast, the waste acid was treated using a traditional O3 / H2O2 process, with ozone dosage of 20 mg / L and hydrogen peroxide (H2O2) dosage the same as in Example 1.

[0045] After treatment, the TOC of the waste acid was 385.2 mg / L, which failed to meet the company's requirements.

[0046] The specific test results are shown in Table 1: Table 1

[0047] Example 2 Combination Figure 1 This embodiment provides a concentrated waste acid purification process and apparatus based on ultraviolet photocatalytic oxidation, specifically including: The sample was taken from synthetic waste acid from a chemical plant. Testing showed TOC = 1200 mg / L and UVT of the raw water = 75%. [The following appears to be a separate, unrelated sentence:] [Setting...] =0.75 and =1.2, and the calculation shows that the hydrogen peroxide (H2O2) dosage is approximately 11127.3 mg / L (calculated at a concentration of 27.5%). The actual operating process parameters are: Step 1 185nm UV / H2O2 process The gas flow rate was controlled at 1 L / min·L, and the ultraviolet light intensity was 15 mW / cm. 2 The reaction time was 45 minutes, and 6676.4 mg / L of hydrogen peroxide (H2O2) was added.

[0048] The second step is the 254nm UV / H2O2 process. Oxalic acid was added at a dosage of 0.08 wt%, with a UV intensity of 35 mW / cm². 2 The reaction time was 45 minutes, and 4450.9 mg / L of hydrogen peroxide (H2O2) was added.

[0049] After the above two-stage oxidation treatment, the TOC of the waste acid was reduced to 6.8 mg / L, and the treatment effect met the company's subsequent process or emission requirements.

[0050] Comparative Example 2A In comparison, the other treatment conditions were the same as in Example 2, and the same waste acid was treated. The difference was that no oxalic acid was added during the 254nm UV / H2O2 process, while the other conditions were exactly the same as in Example 2.

[0051] After treatment, the TOC of the waste acid was 36.4 mg / L, which failed to meet the company's requirements.

[0052] Comparative Example 2B In comparison, the other treatment conditions were the same as in Example 1, and the same waste acid was treated. The difference was that only the 185nm UV / H2O2 process was used for the entire reaction for 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0053] After treatment, the TOC of the waste acid was 155.2 mg / L, which failed to meet the company's requirements.

[0054] Comparative Example 2C In comparison, the other treatment conditions were the same as in Example 1, and the same waste acid was treated. The difference was that only the 254nm UV / H2O2 process was used for the entire reaction for 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0055] After treatment, the TOC of the waste acid was 128.4 mg / L, which failed to meet the company's requirements.

[0056] Comparative 2D In contrast, the waste acid was treated using a traditional O3 / H2O2 process, with ozone dosage of 30 mg / L and hydrogen peroxide (H2O2) dosage the same as in Example 2.

[0057] After treatment, the TOC of the waste acid was 306.4 mg / L, which failed to meet the company's requirements.

[0058] The specific test results are shown in Table 2: Table 2

[0059] Example 3 Combination Figure 1 This embodiment provides a concentrated waste acid purification process and apparatus based on ultraviolet photocatalytic oxidation, specifically including: The sample was waste acid generated during the production process of a chemical company. Testing showed TOC = 3000 mg / L and UVT of the raw water = 50%. [The following is a separate, unrelated sentence:] The sample was set... =0.9 and =1.5, calculations show that the hydrogen peroxide (H2O2) dosage is approximately 41727.3 mg / L (converted to a concentration of 27.5%). The actual operating process parameters are: Step 1 185nm UV / H2O2 process The gas flow rate was controlled at 1.5 L / min·L, and the ultraviolet light intensity was 20 mW / cm². 2 The reaction time was 60 minutes, and 29209.1 mg / L of hydrogen peroxide (H2O2) was added.

[0060] The second step is the 254nm UV / H2O2 process. Oxalic acid was added at a dosage of 0.08 wt%, with an ultraviolet light intensity of 40 mW / cm², a reaction time of 60 minutes, and hydrogen peroxide (H₂O₂) at a concentration of 12518.2 mg / L.

[0061] After the above two-stage oxidation treatment, the TOC of the waste acid was reduced to 6.8 mg / L, and the treatment effect met the company's subsequent process or emission requirements.

[0062] Comparative Example 3A In comparison, the other treatment conditions were the same as in Example 1, and the same waste acid was treated. The difference was that no oxalic acid was added during the 254nm UV / H2O2 process, and the other conditions were exactly the same as in Example 3.

[0063] After treatment, the TOC of the waste acid was 17.8 mg / L, which failed to meet the company's requirements.

[0064] Comparative Example 3B In comparison, the other treatment conditions were the same as in Example 1, and the same waste acid was treated. The difference was that only the 185nm UV / H2O2 process was used for the entire reaction for 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0065] After treatment, the TOC of the waste acid was 268.5 mg / L, which failed to meet the company's requirements.

[0066] Comparative Example 3C In comparison, the other treatment conditions were the same as in Example 1, and the same waste acid was treated. The difference was that only the 254nm UV / H2O2 process was used for the entire reaction for 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0067] After treatment, the TOC of the waste acid was 198.8 mg / L, which failed to meet the company's requirements.

[0068] Comparative 3D In contrast, the waste acid was treated using a traditional O3 / H2O2 process, with ozone dosage of 30 mg / L and hydrogen peroxide (H2O2) dosage being the same as in Example 3.

[0069] After treatment, the TOC of the waste acid was 298.4 mg / L, which failed to meet the company's requirements.

[0070] The specific test results are shown in Table 3: Table 3

[0071] Example 4 Combination Figure 1 This embodiment provides a concentrated waste acid purification process and apparatus based on ultraviolet photocatalytic oxidation, specifically including: The sample was taken from synthetic waste acid from a pesticide company. Testing showed TOC = 245 mg / L and UVT of the raw water = 90%. =0.5 and =1, and calculations show that the hydrogen peroxide (H2O2) dosage is approximately 1262.1 mg / L (calculated at a concentration of 27.5%). The actual operating process parameters are: Step 1 185nm UV / H2O2 process The gas flow rate was controlled at 0.5 L / min·L, and the ultraviolet light intensity was 5 mW / cm². 2 The reaction time was 30 minutes, and 819.1 mg / L of hydrogen peroxide (H2O2) was added.

[0072] The second step is the 254nm UV / H2O2 process. Oxalic acid was added at a dosage of 0.05 wt%, with an ultraviolet light intensity of 20 mW / cm². 2 The reaction time was 30 minutes, and 443 mg / L of hydrogen peroxide (H2O2) was added.

[0073] After the above two-stage oxidation treatment, the TOC of the waste acid was reduced to 6.5 mg / L, and the treatment effect met the company's subsequent process or emission requirements.

[0074] Comparative Example 4A In comparison, the other treatment conditions were the same as in Example 4, and the same waste acid was treated. The difference was that no oxalic acid was added during the 254nm UV / H2O2 process, while the other conditions were exactly the same as in Example 4.

[0075] After treatment, the TOC of the waste acid was 12.4 mg / L, which failed to meet the company's requirements.

[0076] Comparative Example 4B In comparison, the other treatment conditions were the same as in Example 4, and the same waste acid was treated. The difference was that only the 185nm UV / H2O2 process was used, the entire reaction lasted 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0077] After treatment, the TOC of the waste acid was 68.5 mg / L, which failed to meet the company's requirements.

[0078] Comparative Example 4C In comparison, the other treatment conditions were the same as in Example 4, and the same waste acid was treated. The difference was that only the 254nm UV / H2O2 process was used, the entire reaction lasted 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0079] After treatment, the TOC of the waste acid was 75.7 mg / L, which failed to meet the company's requirements.

[0080] Comparative 4D In contrast, the waste acid was treated using a traditional O3 / H2O2 process, with ozone dosage of 15 mg / L and hydrogen peroxide (H2O2) dosage the same as in Example 4.

[0081] After treatment, the TOC of the waste acid was 170.8 mg / L, which failed to meet the company's requirements.

[0082] The specific test results are shown in Table 4: Table 4

[0083] Example 5 Combination Figure 1 This embodiment provides a concentrated waste acid purification process and apparatus based on ultraviolet photocatalytic oxidation, specifically including: The sample was waste acid generated during the production process of a pharmaceutical company. Testing showed TOC = 3545 mg / L and UVT of the raw water = 50%. [The following is a separate, unrelated sentence:] The sample was set as waste acid generated during the production process of a pharmaceutical company. =0.9 and =1.5, calculations show that the hydrogen peroxide (H2O2) dosage is approximately 49308 mg / L (converted to a concentration of 27.5%). The actual operating process parameters are: Step 1 185nm UV / H2O2 process The gas flow rate was controlled at 1.5 L / min·L, and the ultraviolet light intensity was 20 mW / cm². 2 The reaction time was 60 minutes, and 34759 mg / L of hydrogen peroxide (H2O2) was added.

[0084] The second step is the 254nm UV / H2O2 process. Oxalic acid was added at a dosage of 0.08 wt%, with a UV intensity of 40 mW / cm². 2 The reaction time was 60 minutes, and 14549 mg / L of hydrogen peroxide (H2O2) was added.

[0085] After the above two-stage oxidation treatment, the TOC of the waste acid was reduced to 7.9 mg / L, and the treatment effect met the company's subsequent process or emission requirements.

[0086] Comparative Example 5A In comparison, the other treatment conditions were the same as in Example 5, and the same waste acid was treated. The difference was that no oxalic acid was added during the 254nm UV / H2O2 process, while the other conditions were exactly the same as in Example 5.

[0087] After treatment, the TOC of the waste acid was 21.3 mg / L, which failed to meet the company's requirements.

[0088] Comparative Example 5B In contrast, the other treatment conditions were the same as in Example 5, and the same waste acid was treated. The difference was that only the 185nm UV / H2O2 process was used for the entire reaction for 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0089] After treatment, the TOC of the waste acid was 254.2 mg / L, which failed to meet the company's requirements.

[0090] Comparative Example 5C In comparison, the other treatment conditions were the same as in Example 1, and the same waste acid was treated. The difference was that only the 254nm UV / H2O2 process was used for the entire reaction for 60 minutes, and all hydrogen peroxide (H2O2) was added to this process.

[0091] After treatment, the TOC of the waste acid was 188.7 mg / L, which failed to meet the company's requirements.

[0092] Comparative 5D In contrast, the waste acid was treated using a conventional O3 / H2O2 process, with ozone dosage of 30 mg / L and hydrogen peroxide (H2O2) dosage the same as in Example 5.

[0093] After treatment, the TOC of the waste acid was 302.8 mg / L, which failed to meet the company's requirements.

[0094] The specific test results are shown in Table 5: Table 5

[0095] In summary, the two-stage ultraviolet catalytic oxidation method adopted in this invention, compared with single-wavelength oxidation processes (Comparative Examples B and C), processes lacking photosensitizers (Comparative Example A), or traditional oxidation processes (Comparative Example D), achieves a significant improvement in TOC removal efficiency under the same total oxidant dosage, and the final effluent water quality can stably meet the needs of enterprises.

[0096] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0097] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A concentrated waste acid purification process based on ultraviolet photocatalytic oxidation, characterized in that, Includes the following steps: Step 1 185nm UV / H2O2 process S11. Aeration is performed by introducing oxygen-containing gas into the waste acid to be treated. S12. The waste acid is irradiated with ultraviolet light with a wavelength of 185 nm, so that the oxygen-containing gas generates ozone (O3) in situ under the action of ultraviolet light. S13. Add hydrogen peroxide (H2O2) to the waste acid and irradiate it with ultraviolet light with a wavelength of 254 nm to activate the hydrogen peroxide (H2O2) and generate hydroxyl radicals (·OH). The second step is the 254nm UV / H2O2 process. S21. Hydrogen peroxide (H2O2) and organic polycarboxylic acids are added to the waste acid after step S13. The organic polycarboxylic acids act as micro-zone pH buffers to promote the generation of hydroxyl radicals (·OH). S22. Using ultraviolet light with a wavelength of 254 nm to irradiate the waste acid, under conditions of no pH adjustment and no addition of metal catalysts, the direct oxidation by ozone (O3) and the oxidation by hydroxyl radicals (·OH) synergistically degrade organic pollutants.

2. The concentrated waste acid purification process based on ultraviolet photocatalytic oxidation as described in claim 1, characterized in that, The irradiation intensity of the 185 nm ultraviolet light is 5–20 mW / cm², the irradiation intensity of the 254 nm ultraviolet light is 20–40 mW / cm², and the reaction time is 30–60 min.

3. The concentrated waste acid purification process based on ultraviolet photocatalytic oxidation as described in claim 1, characterized in that, The oxygen-containing gas is air or oxygen, and the gas flow rate is 0.1–2 L / min·L.

4. The concentrated waste acid purification process based on ultraviolet photocatalytic oxidation according to claim 1, characterized in that, The organic polycarboxylic acid is at least one of citric acid, oxalic acid, and tartaric acid.

5. The concentrated waste acid purification process based on ultraviolet photocatalytic oxidation according to claim 1, characterized in that, The concentration of the organic polycarboxylic acid is 0.01–0.1 wt%.

6. The concentrated waste acid purification process based on ultraviolet photocatalytic oxidation according to claim 1, characterized in that, The amount of hydrogen peroxide (H2O2) added needs to be measured based on the TOC and UVT levels of the influent, and then the control system will add it in stages. The specific calculation formula is as follows: ; in This represents the required oxidant dosage (mg / L); TOC in TOC (mg / L) in the influent representing waste acid; TOC out This represents the desired TOC (mg / L) level for the waste acid effluent. =34 g / mol; M TOC =12g / mol; The default value for the oxidation efficiency coefficient is between 0.5 and 0.

9. It can be verified by measuring the UVT value of the waste acid. When UVT ≥ 80% is high, 0.5 can be selected as the coefficient. When UVT ≤ 50% is low, 0.9 can be selected as the coefficient. When UVT is between the two, a coefficient between 0.5 and 0.9 can be selected. The default safety factor is 1-1.

5.

7. The concentrated waste acid purification process based on ultraviolet photocatalytic oxidation according to claim 1, characterized in that, The waste acid is waste hydrochloric acid, waste sulfuric acid, or a mixed acid, with a TOC concentration of 100–5000 mg / L and a pH < 1.

8. A concentrated waste acid purification device for implementing any one of claims 1-7 based on ultraviolet photocatalytic oxidation, characterized in that, include: The reactor body is a sealed cavity resistant to strong acid corrosion; The ultraviolet light source unit includes at least one set of ultraviolet lamps emitting a wavelength of 185nm and at least one set of ultraviolet lamps emitting a wavelength of 254nm; A gas distribution unit is located at the bottom of the reactor body and is used to introduce oxygen-containing gas into the waste acid; The reagent dosing unit includes a hydrogen peroxide storage tank and an organic polycarboxylic acid storage tank connected to the reactor, and is equipped with a metering pump.

9. The concentrated waste acid purification device based on ultraviolet photocatalytic oxidation according to claim 8, characterized in that, It also includes a control system connected to the online water quality monitoring instrument and the reagent dosing unit, the control system being configured to control the amount of hydrogen peroxide added based on the monitored TOC and UVT data.

10. The concentrated waste acid purification device based on ultraviolet photocatalytic oxidation according to claim 8, characterized in that, The inner wall of the reactor body is lined with PTFE, PFA or quartz material.

11. The concentrated waste acid purification device based on ultraviolet photocatalytic oxidation according to claim 8, characterized in that, The ultraviolet lamp is a low-pressure mercury lamp. The 185nm ultraviolet lamp can emit 185nm and 254nm ultraviolet light simultaneously. The transmittance of the outer quartz sleeve is ≥ 90% at a wavelength of 185nm and ≥ 95% at a wavelength of 254nm.

12. The concentrated waste acid purification device based on ultraviolet photocatalytic oxidation according to claim 8, characterized in that, The online water quality monitoring instrument includes at least an online TOC analyzer and a UV254 sensor.

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