A method for removing organic pollutants from wastewater using a photo-excited carbon dioxide conversion chemical oxidation system.
The chemical oxidation system that converts carbon dioxide into peroxybicarbonate through photo-excitation solves the problem of the difficulty in efficiently removing organic wastewater pollutants in existing technologies, and achieves a highly efficient oxidation effect without catalysts or acid requirements.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LANZHOU INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-01-31
- Publication Date
- 2026-05-26
AI Technical Summary
Existing technologies for treating recalcitrant organic wastewater have limitations such as stringent requirements on water pH, the need to add acid and alkali reagents for adjustment, secondary pollution from iron sludge, and ineffective decomposition of hydrogen peroxide by the Hubble-Weiss reaction, which restrict the application potential of chemical oxidation methods.
A chemical oxidation system based on photo-excited carbon dioxide conversion is adopted. Carbon dioxide is used as an oxidant to generate peroxybicarbonate under photoexcitation. Through photolysis and activation of hydrogen peroxide, a variety of reactive oxygen species are generated, which synergistically enhance the oxidation and removal of organic pollutants, avoiding the need for catalysts and acidity, and achieving zero secondary pollution.
It significantly improves the utilization rate of hydrogen peroxide and the yield of reactive oxygen species, achieving efficient and economical oxidative removal of organic pollutants under mild reaction conditions, without the need for catalysts or acid adjustment.
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Abstract
Description
Technical Field
[0001] This invention relates to a method for removing organic pollutants from wastewater using a photo-excited carbon dioxide conversion chemical oxidation system, belonging to the field of advanced oxidation technology. Background Technology
[0002] With the rapid development of my country's economy, a large amount of recalcitrant organic wastewater is generated from industry, agriculture, and animal husbandry. Simultaneously, these recalcitrant organic pollutants are gradually entering environmental water bodies, causing widespread impact, posing significant challenges to treatment, and resulting in substantial harm to environmental ecosystems. Therefore, there is an urgent need to develop economical and efficient methods and technologies for treating organic pollutants in wastewater. Although based on Fe... 2+ Fenton oxidation, which activates and decomposes hydrogen peroxide, can effectively oxidize and degrade organic pollutants in wastewater, but it still has many problems, such as: strict requirements on the pH range of the water body, requiring the addition of acid and alkali reagents to adjust the pH, increasing operating costs; the addition of ferrous catalysts easily produces iron sludge, causing secondary pollution; changes in the system's pH value lead to catalyst leaching and deactivation; and the presence of the Haber-Wes reaction makes it impossible to inhibit the ineffective decomposition of hydrogen peroxide. The photo-Fenton method developed in recent years, although it can enhance mass transfer and improve treatment efficiency, still cannot overcome the above shortcomings, limiting the application potential of chemical oxidation methods for removing organic pollutants from wastewater. Therefore, developing a novel chemical oxidation system that can efficiently utilize hydrogen peroxide, is low-cost, and produces no secondary pollution for the removal of organic pollutants from wastewater is of great significance. Summary of the Invention
[0003] The purpose of this invention is to provide a method for removing organic pollutants from wastewater using a photo-excited carbon dioxide conversion chemical oxidation system. This system innovatively uses carbon dioxide as the oxidant feedstock. Under photoexcitation, it improves the utilization rate of hydrogen peroxide and the yield of reactive oxygen species by altering the reaction pathway of hydrogen peroxide, significantly enhancing the oxidation and removal capacity of organic pollutants in wastewater. Simultaneously, the reaction system requires no catalyst, has no acidity requirements, produces no secondary pollution, and operates under mild reaction conditions, exhibiting excellent economic efficiency and broad application prospects.
[0004] To achieve the above-mentioned objectives, the specific technical solution adopted by the present invention includes:
[0005] Carbon dioxide is passed into organic wastewater containing carbonates, and hydrogen peroxide is added. Under irradiation with a light source of 380 nm to 850 nm wavelength, the mixture is stirred at room temperature for 2 to 5 minutes to generate the oxidant peroxybicarbonate. Under photoexcitation, pollutant molecules change from the ground state to the excited state, significantly increasing their reactivity. The energy of the photons can not only directly photodegrade organic pollutants but also activate and decompose peroxybicarbonate to produce various reactive oxygen species such as OH and CO3. - ·、O2 -·、 1 O2 and hydrogen peroxide can also be rapidly activated and decomposed to generate hydroxyl radicals; at the same time, the heat generated during the light irradiation process increases the mass transfer rate of the reaction system, thereby synergistically removing organic pollutants from wastewater through oxidation.
[0006] The chemical reaction equations that occur during the photoexcitation process are as follows:
[0007]
[0008] The carbonate is one or a combination of two or more of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate. The concentration of the carbonate in the organic wastewater is 0.1 mmol / L to 3 mol / L. The molar ratio of the carbonate to hydrogen peroxide is 0.1:1 to 20:1. The pH of the organic wastewater is 6 to 10.
[0009] The organic pollutants include antibiotics, endocrine disruptors, pesticides, azo dyes, phenol, chlorophenols, polychlorinated biphenyls, aniline compounds, and polycyclic aromatic hydrocarbons.
[0010] In summary, this invention innovatively utilizes CO2 as a raw material to induce a series of chemical reactions between CO2 and hydrogen peroxide in organic wastewater containing carbonates under specific wavelength light irradiation conditions, generating peroxybicarbonate. Under photoexcitation conditions, pollutant molecules transform from the ground state to the excited state, significantly increasing reactivity. The energy of photons can not only directly photodegrade organic pollutants but also activate and decompose peroxybicarbonate to generate various reactive oxygen species. Hydrogen peroxide can also be rapidly activated and decomposed to generate hydroxyl radicals. Simultaneously, the heat energy generated during light irradiation enhances the mass transfer rate of the reaction system, thereby synergistically and effectively removing organic pollutants from wastewater. Compared to Fenton oxidation and photo-Fenton oxidation technologies, this method requires no catalyst, does not require acidic reaction conditions, and produces no secondary pollution. By converting hydrogen peroxide into peroxybicarbonate under light irradiation, it alters the traditional reaction pathway of hydrogen peroxide activation and decomposition, thereby improving the utilization rate of hydrogen peroxide and the yield of reactive oxygen species, and avoiding the ineffective decomposition of hydrogen peroxide. Therefore, this method has excellent economic benefits and application potential. Detailed Implementation
[0011] To make the objectives, technical solutions, and advantages of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the following embodiments. The specific embodiments described are only for explaining the invention and are not intended to limit the invention.
[0012] Example 1
[0013] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 315 nm to 400 nm, CO2 gas was passed into a 100 mg / L tetracycline wastewater containing 0.5 mol / L sodium carbonate, and 0.5 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 8.4. After stirring the reaction at room temperature for 5 minutes, the tetracycline degradation rate was 99%.
[0014] Comparative Example 1
[0015] The light source was turned off, and CO2 gas was introduced into a 100 mg / L tetracycline wastewater containing 0.5 mol / L sodium carbonate. 0.5 mol / L hydrogen peroxide was added, and the pH of the wastewater was measured to be approximately 8.4. After stirring the reaction at room temperature for 5 minutes, the tetracycline degradation rate was 23%.
[0016] Example 2
[0017] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 315 nm to 400 nm, CO2 gas was passed into 100 mg / L oxytetracycline wastewater containing 3 mol / L sodium carbonate, and 0.5 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 10.0. After stirring the reaction at room temperature for 3 minutes, the degradation rate of oxytetracycline was 96.5%.
[0018] Comparative Example 2
[0019] The aforementioned light source was turned off, and CO2 gas was introduced into a 100 mg / L oxytetracycline wastewater containing 5 mol / L sodium carbonate. 0.5 mol / L hydrogen peroxide was added, and the pH of the wastewater was measured to be approximately 9.0. After stirring the reaction at room temperature for 3 minutes, the oxytetracycline degradation rate was 28.3%.
[0020] Example 3
[0021] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 315 nm to 400 nm, CO2 gas was passed into 50 mg / L p-chlorophenol wastewater containing 0.1 mol / L sodium carbonate, and 1 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 8.0. After stirring the reaction at 25 °C for 40 minutes, the degradation rate of p-chlorophenol was 96%.
[0022] Comparative Example 3
[0023] The aforementioned light source was turned off, and CO2 gas was introduced into a 50 mg / L p-chlorophenol wastewater containing 0.1 mol / L sodium carbonate. 1 mol / L hydrogen peroxide was added, and the pH of the wastewater was measured to be approximately 8.0. 0.8 g / L of alumina-supported copper oxide catalyst was added, and the reaction was stirred at 25 °C for 40 minutes, resulting in a 78% degradation rate of p-chlorophenol.
[0024] Example 4
[0025] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 315 nm to 400 nm, CO2 gas was passed into anthracene wastewater containing 5 mmol / L sodium carbonate at a concentration of 25 mg / L. 5 mmol / L hydrogen peroxide was also added, and the pH of the wastewater was measured to be approximately 8.0. After stirring at 60°C for 30 minutes, the degradation rate of anthracene was 97%.
[0026] Comparative Example 4
[0027] The aforementioned light source was turned off, and CO2 gas was introduced into anthracene wastewater containing 5 mmol / L sodium carbonate at a concentration of 25 mg / L. 5 mmol / L hydrogen peroxide was added, and the pH of the wastewater was measured to be approximately 8.0. 0.2 g / L of hydroxyapatite-supported nickel oxide catalyst was added, and the reaction was stirred at 60 °C for 30 minutes, resulting in an anthracene degradation rate of 75%.
[0028] Example 5
[0029] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 315 nm ~ 400 nm, CO2 gas was passed into 100 mg / L bisphenol A wastewater containing 3 mol / L sodium carbonate, and 0.5 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 9.8. After stirring the reaction at room temperature for 5 minutes, the degradation rate of bisphenol A was 93.5%.
[0030] Example 6
[0031] Under irradiation conditions of a light source with a power of 100 W and a wavelength of 400 nm to 830 nm, CO2 gas was passed into a 50 mg / L imidacloprid wastewater containing 0.2 mol / L potassium carbonate, and 0.2 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 6.0. After stirring the reaction at room temperature for 5 minutes, the imidacloprid degradation rate was 89%.
[0032] Example 7
[0033] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 400 nm to 830 nm, CO2 gas was passed into 100 mg / L methyl orange wastewater containing 1 mol / L sodium bicarbonate, and 1 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 7.6. After stirring the reaction at room temperature for 5 minutes, the degradation rate of methyl orange was 96%.
[0034] Example 8
[0035] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 400 nm to 830 nm, CO2 gas was passed into 50 mg / L Acid Red wastewater containing 1 mol / L sodium bicarbonate, and 0.5 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 7.8. After stirring the reaction at room temperature for 5 minutes, the degradation rate of Acid Red was 95%.
[0036] Example 9
[0037] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 470 nm ~ 500 nm, CO2 gas was passed into 50 mg / L phenol wastewater containing 0.5 mol / L sodium bicarbonate, and 0.5 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 6.0. After stirring the reaction at room temperature for 5 minutes, the phenol degradation rate was 92%.
[0038] Example 10
[0039] Under irradiation conditions of a 100 W light source with a wavelength of 470 nm to 500 nm, CO2 gas was passed into 80 mg / L o-dichlorophenol wastewater containing 0.5 mol / L potassium carbonate, and 0.5 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 6.9. After stirring the reaction at room temperature for 5 minutes, the degradation rate of o-dichlorophenol was 97%.
[0040] Example 11
[0041] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 640 nm to 780 nm, CO2 gas was passed into 50 mg / L polychlorinated biphenyl (PCB) wastewater containing 2 mol / L sodium carbonate, and 1 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 8.8. After stirring the reaction at room temperature for 3 minutes, the PCB degradation rate was 97%.
[0042] Example 12
[0043] Under irradiation conditions of a light source with a power of 100 W and a wavelength of 470 nm ~ 500 nm, CO2 gas was passed into a 100 mg / L toluene wastewater containing 1 mol / L potassium carbonate, and 0.5 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 7.7. After stirring the reaction at room temperature for 3 minutes, the toluene degradation rate was 99%.
[0044] Example 13
[0045] Under irradiation conditions of a 100 W light source with a wavelength of 640 nm ~ 780 nm, CO2 gas was passed into a 50 mg / L polyvinyl alcohol wastewater containing 1 mol / L sodium bicarbonate, and 0.5 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 8.5. After stirring the reaction at room temperature for 5 minutes, the polyvinyl alcohol degradation rate was 92%.
[0046] Example 14
[0047] Under irradiation conditions of a light source with a power of 100 W and a wavelength of 640 nm to 780 nm, CO2 gas was passed into 100 mg / L aniline wastewater containing 0.1 mol / L potassium carbonate, and 0.1 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 7.8. After stirring the reaction at room temperature for 5 minutes, the aniline degradation rate was 96%.
[0048] Example 15
[0049] Under irradiation conditions of a light source with a power of 25 W and a wavelength of 505 nm to 515 nm, CO2 gas was passed into 100 mg / L fluorene wastewater containing 2 mol / L sodium carbonate, and 1 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 9. After stirring the reaction at room temperature for 3 minutes, the fluorene degradation rate was 89%.
[0050] Example 16
[0051] Under irradiation conditions of a 100 W light source with a wavelength of 315 nm to 400 nm, CO2 gas was passed into a 50 mg / L benzo[a]pyrene wastewater containing 0.5 mol / L sodium carbonate, and 0.5 mol / L hydrogen peroxide was added. The pH of the wastewater was measured to be approximately 8.5. After stirring the reaction at room temperature for 5 minutes, the benzo[a]pyrene degradation rate was 95%.
[0052] In summary, under photoluminescence, a novel advanced oxidation system that converts CO2 into peroxybicarbonate can rapidly oxidize and degrade various aquatic organic pollutants, including antibiotics, endocrine disruptors, pesticides, azo dyes, phenol, chlorophenol, polychlorinated biphenyls, aniline compounds, and polycyclic aromatic hydrocarbons. This system boasts advantages such as simple operation, low cost, and high efficiency, demonstrating broad application prospects. Comparative experiments show that keeping other reaction conditions constant and turning off the light source significantly reduces the degradation rate of organic pollutants. This indicates that photoirradiation is a necessary condition for this oxidation system. Furthermore, under the same conditions, compared to reactions involving a catalyst, the photo-excitation process significantly improves the pollutant degradation rate. In subsequent applications, the concentration of sodium or potassium carbonate or hydroxide, hydrogen peroxide, or photoirradiation intensity can be appropriately adjusted based on the concentration of organic pollutants in the wastewater to achieve even better oxidation and removal effects.
[0053] The above are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Any changes or modifications made based on the scope of the patent and the contents of the specification of the present invention should fall within the protection scope of the technical solution of the present invention.
Claims
1. A method for removing organic pollutants from wastewater using a photo-excited carbon dioxide conversion chemical oxidation system, characterized in that: Carbon dioxide is passed into organic wastewater containing carbonates, and hydrogen peroxide is added. Under irradiation with a light source of 470 nm to 850 nm wavelength, the mixture is stirred at room temperature for 2 to 5 minutes to generate the oxidant peroxybicarbonate. Under photoexcitation, pollutant molecules change from the ground state to the excited state, significantly increasing their reactivity. The energy of the photons can not only directly photodegrade organic pollutants but also activate and decompose peroxybicarbonate to produce various reactive oxygen species such as OH and CO3. - ·、O2 - ·、 1 O2; hydrogen peroxide can also be rapidly activated and decomposed to generate hydroxyl radicals; at the same time, the heat energy generated during the light irradiation process increases the mass transfer rate of the reaction system, thereby synergistically removing organic pollutants from wastewater through oxidation. The chemical reactions that occur during photoexcitation are as follows: ； The method requires no catalyst throughout the process, and the initial pH of the organic wastewater is 6-10.
2. The method for removing organic pollutants from wastewater using a photo-excited carbon dioxide conversion chemical oxidation system as described in claim 1, characterized in that: The carbonate is one or a combination of two or more of sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate.
3. The method for removing organic pollutants from wastewater using a photo-excited carbon dioxide conversion chemical oxidation system as described in claim 1, characterized in that: The concentration of the carbonate in the organic wastewater is 0.1 mmol / L to 3 mol / L.
4. The method for removing organic pollutants from wastewater using a photo-excited carbon dioxide conversion chemical oxidation system as described in claim 1, characterized in that: The molar ratio of carbonate to hydrogen peroxide is 0.1:1 to 20:
1.
5. The method for removing organic pollutants from wastewater using a photo-excited carbon dioxide conversion chemical oxidation system as described in claim 1, characterized in that: The organic pollutants include antibiotics, endocrine disruptors, pesticides, azo dyes, phenol, chlorophenols, polychlorinated biphenyls, aniline compounds, and polycyclic aromatic hydrocarbons.