Phthalocyanine catalytic oxidation method for removing nitrite nitrogen and application
Through the catalytic oxidation reaction of ammonium sulfonate cobalt phthalocyanine, the oxygen molecules in water are activated and nitrite is converted into nitrate, which solves the problem of low removal efficiency and pollution of nitrite nitrogen in water, and achieves high efficiency, environmental protection and economical Water purification effect.
Patent Information
- Application Number
- CN202411225881.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-03
- Publication Date
- 2024-12-13
AI Technical Summary
The prior art is not efficient, costly and may cause secondary pollution in removing nitroso nitrogen in water bodies, and lacks an efficient, pollution-free, energy-saving and economical treatment method.
Using ammonium sulfonate cobalt phthalocyanine as a catalyst, the oxygen molecules in water are activated through catalytic oxidation reaction, and nitrite is converted into nitrate, thereby reducing the toxicity of nitrite nitrogen, and using its water solubility and stability in a neutral environment. Long-term use.
It achieves efficient, environmentally friendly and long-lasting removal of nitroso nitrogen, significantly reduces the toxicity of nitroso nitrogen, avoids secondary pollution, and has a small amount of catalyst and low cost. It is suitable for aquaculture and industrial sewage treatment.
Abstract
Description
Technical Field
[0001] The present invention belongs to the field of catalytic science and technology, and is a method for catalytic oxidation removal of nitrite nitrogen developed based on the activation effect of cobalt phthalocyanine catalyst on oxygen molecules. Sulfonic ammonium phthalocyanine cobalt is used as a catalyst to catalyze the activation and oxidation of dissolved oxygen in water to convert nitrite into nitrate, thereby reducing the toxicity of nitrite nitrogen to water bodies, and can be used for the treatment of nitrite nitrogen in aquaculture, industrial sewage and environmental water. Background Art
[0002] With the development of aquaculture, industry and urbanization, water pollution is becoming increasingly serious. - ) is a common water pollutant and an intermediate product of the nitrogen cycle. It is mainly transformed from ammonia nitrogen under the action of microorganisms and has attracted widespread attention. It mainly comes from industrial emissions, domestic sewage and agricultural pollution, such as planting, animal husbandry and aquaculture in agriculture. Nitrite nitrogen not only has a serious impact on the ecosystem, but also poses a potential hazard to human health through the food chain. Studies have shown that nitrite nitrogen has toxic effects such as carcinogenicity, teratogenicity and mutagenicity. Long-term exposure to a nitrite nitrogen polluted environment will pose a serious threat to human health. Therefore, finding an efficient and low-cost method for removing nitrite nitrogen and improving the removal efficiency of nitrite nitrogen are of great research significance for improving the quality of my country's water environment and ensuring the safety of drinking water for the people.
[0003] Common nitrogen-containing wastewater treatment technologies include physical, chemical and biological methods. The physical method uses substances with high adsorption capacity to effectively absorb NO2 - Adsorbed into the structure of these substances themselves, many products contain adsorbent components, which have the significant advantages of rapid reaction and low cost. However, if the amount is too much, it will increase the cost.
[0004] Chemical methods usually adopt oxidation and reduction methods. For example, oxidation method can significantly and effectively oxidize nitrite with H2O2 under the catalytic effect of UV light. Oxidation method can also remove nitrite under the catalysis of sodium hypochlorite. Sodium hypochlorite can not only effectively and quickly remove nitrite, but also has a removal rate of up to 89.1%. Reduction method, for example, cast iron chips have excellent ability in nitrite removal. The amount of cast iron chips used is proportional to the effect of nitrite removal, that is, the greater the amount of cast iron chips used, the more significant the removal effect. Under weak acidic conditions, Fe in cast iron chips can effectively reduce nitrite to nitrogen or ammonia nitrogen, thereby effectively removing nitrite. In addition, when the catalyst acts together with H2, the reduction removal efficiency of nitrite is significantly improved, and nitrite can be efficiently converted into N2, accompanied by a by-product NH4 +The generation of. For example, oxygen vacancies will appear on the supported palladium catalyst. This characteristic allows the nitrite in the aquaculture water to be rapidly catalytically reduced by the catalyst. In addition, there is the nitrite reduction and removal technology catalyzed by a bimetallic catalyst. Under the action of the catalyst, nitrite nitrogen is mainly converted into nitrogen gas, accounting for up to 98%, and ammonia, achieving efficient nitrite treatment. This method can completely reduce and remove nitrite nitrogen with an initial concentration of 100 mg / L. Its significant advantages are simple operation and high degree of automation, and it is especially suitable for small water treatment systems. However, in the application of chemical methods, if the operation is improper, it may cause secondary pollution of the water body and cause potential toxic effects on aquatic organisms.
[0005] Biological method usually uses microorganisms to treat water quality, such as photosynthetic bacteria, nitrifying bacteria, Candida, Bacillus megaterium and Lactobacillus brevis. Nitrifying bacteria are unique among these microorganisms. They can degrade sodium nitrite with excessive concentration in water into non-toxic substances, such as nitrogen and nitrates, by absorbing and converting it. Under the action of nitrifying bacteria, sodium nitrite can be converted into nitrate in an aerobic environment, thereby purifying water quality. When the environment is hypoxic, sodium nitrite will be reduced to nitrogen oxides or nitrogen by denitrifying bacteria. In theory, nitrifying bacteria and denitrifying bacteria should be able to effectively reduce the content of sodium nitrite. However, since these bacteria are chemoautotrophic bacteria, their growth and reproduction speed is relatively slow, and they are restricted by many factors such as water environment, survival rate and preservation technology. Therefore, the method of using denitrifying bacteria and nitrifying bacteria to degrade sodium nitrite is not ideal in practical applications.
[0006] In addition to the above three methods, there is also an electrode biofilm denitrification technology that combines biological reduction with electrochemistry. The significant advantages of electrode biofilm denitrification technology are easy control, stable effect and high removal efficiency. The electrode biofilm method has excellent denitrification efficiency and can achieve a nitrite removal efficiency of up to 93%.
[0007] In general, some important achievements have been made in the removal of nitrite nitrogen from water bodies, providing valuable experience and inspiration for the development of this field. However, there are still problems such as low removal efficiency and high treatment costs. It is necessary to find more efficient, pollution-free, energy-saving and economical methods to deeply remove nitrite nitrogen from water bodies.
[0008] Based on the technical background of denitrification, it is proposed to select a catalyst to catalyze and activate oxygen molecules to oxidize nitrite nitrogen into nitro nitrogen, such as metal phthalocyanine molecules. When metal phthalocyanine is used as a catalyst, its structure is similar to human hemoglobin. This similarity enables it to have the ability to carry oxygen molecules and activate oxygen molecules. Metal phthalocyanine and its derivatives, especially water-soluble cobalt phthalocyanine compounds, have excellent biomimetic photocatalytic oxidation performance and can exert catalytic performance even under low temperature conditions. Cobalt phthalocyanine is usually used to catalyze oxidative desulfurization. After research, it was found that tetrasulfonate ammonium phthalocyanine cobalt and binuclear hexasulfonate ammonium phthalocyanine cobalt as desulfurization catalysts also have the function of catalytic oxidation conversion of nitrite nitrogen into nitro nitrogen. In theory, it is possible for oxygen to oxidize nitrite to nitrate, as shown in formulas (1) and (2), and practice has also proved that it is feasible. To this end, relevant research was conducted and a phthalocyanine catalytic oxidation method and application for converting nitrite nitrogen were proposed.
[0009] NO3 - +2H + +2e=NO2 - +H2O 0.934E° / V (1)
[0010] O2+4H + +4e=2H2O 1.229E° / V (2) Summary of the invention
[0011] (I) The purpose of the present invention is to provide a method for converting nitrite nitrogen into nitro nitrogen by catalytic oxidation using ammonium sulfonate phthalocyanine cobalt, which is suitable for removing nitrite nitrogen from an aqueous phase.
[0012] (II) Technical solution:
[0013] (1) Catalytic oxidation reaction of nitrite nitrogen conversion. Sulfonated ammonium phthalocyanine cobalt is used as a catalyst for activating oxygen, and a solution of a certain concentration is prepared. A certain volume of the solution is taken, and then a certain volume of a prepared sodium nitrite solution of a certain concentration is absorbed. After mixing, the solution is left to stand at room temperature or stirred magnetically for a certain period of time to perform a catalytic oxidation reaction to remove nitrite nitrogen.
[0014] (2) Color analysis of nitrite nitrogen removal rate. After the above reaction has been carried out for a certain period of time, add a certain volume of p-aminobenzenesulfonic acid of a certain concentration, mix well, and let stand for a certain period of time. Then add a certain volume of naphthylethylenediamine hydrochloride solution of a certain concentration, add water to make up to a certain volume, mix well, let stand for a certain period of time, and measure the absorbance (A) at a specific wavelength. According to the above method, the absorbance (A0) of the system in which the catalyst solution is replaced by the same volume of distilled water is measured. In order to avoid the influence of phthalocyanine color on the analysis results, add the same volume of phthalocyanine solution after the color reaction, and then make up to a certain volume.
[0015] Nitrite ion removal rate = [(A0-A) / A0] × 100% (3)
[0016] (III) Advantages and effects
[0017] (1) Environmentally friendly and harmless. Animal experiments have shown that the ammonium, sodium and potassium salts of cobalt phthalocyanine sulfonate are safe and non-toxic and do not cause any pollution to the environment. The method of removing nitrite nitrogen by catalytic oxidation of ammonium sulfonate cobalt phthalocyanine does not require the addition of an external oxidant and will not cause secondary pollution.
[0018] (2) Long-lasting and effective. Phthalocyanine compounds have relatively stable physical and chemical properties in a near-neutral environment and can be used in water environments for a long time. Ammonium sulfonate phthalocyanine cobalt has good water solubility and is easy to disperse. It has a significant effect in catalytic oxidation to remove nitrite nitrogen. It is used in small amounts and is long-lasting and effective. DETAILED DESCRIPTION
[0019] Example 1
[0020] Catalytic oxidation of nitrite. At room temperature, sulfonated ammonium phthalocyanine cobalt is used as a catalyst for activating oxygen and prepared into a 0.5 mg / mL solution. Take 2 mL of the solution and then absorb 1 mL of a 5 μg / mL NaNO2 solution. Let the reaction stand for a certain period of time at room temperature to carry out the phthalocyanine catalytic oxidation reaction to remove nitrite.
[0021] Example 2
[0022] Analysis method of nitrite removal rate. After a certain period of time of phthalocyanine catalytic oxidation to remove nitrite, add 1mL of 0.4% p-aminobenzenesulfonic acid to the reaction system at room temperature, mix well, and let stand for 5 minutes. Then add 0.5mL of 0.2% naphthylethylenediamine hydrochloride solution, add water to make up to 10mL, mix well, let stand for 15 minutes, and measure the absorbance (A) at 538nm. According to the above method, replace the catalyst solution with 2mL of distilled water, add 2mL of 0.5mg / mL phthalocyanine solution after the system develops color reaction, then make up to 10mL, and measure the absorbance (A0). Then calculate the nitrite removal rate according to formula (3).
[0023] A0 can also be considered as the value after the oxygen in the water body acts on nitrite without adding a catalyst, and its value changes little. Therefore, under the experimental conditions without adding a catalyst, the effect of oxygen in the water body on nitrite can be ignored.
[0024] Example 3
[0025] Using tetrasulfonate ammonium phthalocyanine cobalt as a catalyst, the denitrification reaction was carried out for 1 day as in Example 1. The nitrite nitrogen removal rate in the system was measured and calculated as in Example 2, and was 52.1%.
[0026] Example 4
[0027] Using hexasulfonated ammonium binuclear phthalocyanine cobalt as a catalyst, the denitrification reaction was carried out for 1 day as in Example 1. The nitrite nitrogen removal rate in the system was measured and calculated as in Example 2, and was 32.3%.
[0028] Example 5
[0029] Using tetrasulfonated ammonium phthalocyanine cobalt as a catalyst, 1 mL of 5 μg / mL NaNO2 solution was added to the reaction system 5 times over 5 days, 0.2 mL each time, as in Example 1. After 5 days of reaction, the nitrite nitrogen removal rate in the system was measured and calculated as in Example 2, which was 62.5%.
[0030] Example 6
[0031] Using hexasulfonated ammonium dinuclear phthalocyanine cobalt as a catalyst, 1 mL of a 5 μg / mL NaNO2 solution was added to the reaction system 5 times over 5 days, 0.2 mL each time, as in Example 1. After 5 days of reaction, the nitrite nitrogen removal rate in the system was measured and calculated as in Example 2, which was 40.2%.
[0032] Example 7
[0033] Simulate the removal of nitrous oxide from aquaculture water. Based on the calculation of 100g / 2 mu, the concentration of tetrasulfonate ammonium phthalocyanine cobalt catalyst in water is 7.5×10 -5 mg / mL, the concentration of sodium nitrite in the simulation system should be 5×10 -7 mg / L, i.e. 0.5ppm. Take 2mL of catalyst solution and 1mL of sodium nitrite for reaction. Sodium nitrite is added over 5 days, 0.2mL at a time. According to the above data, the concentration of tetrasulfonic acid aminophthalocyanine cobalt in the experiment is 3.25×10 -4 mg / mL, the concentration of sodium nitrite is 5×10 -6 μg / mL. The color analysis was the same as in Example 2, and the nitrite nitrogen removal rate after 5 days was 90.9%. According to this removal rate, the residual nitrite nitrogen after removal was 0.046ppm, which was lower than 0.1ppm. This value was within the safety range required for aquaculture water.
[0034] Example 8
[0035] As in Example 7, the catalyst was replaced with hexasulfonated ammonium binuclear cobalt phthalocyanine, and the removal rate of nitrite nitrogen was 65.0%.
[0036] Example 9
[0037] For example, the tetrasulfonate ammonium phthalocyanine cobalt solution used in Examples 1 and 4, and the hexasulfonate ammonium binuclear phthalocyanine cobalt solution used in Examples 7 and 8, have no significant change in catalytic ability after being placed for 10 days after preparation, and their catalytic ability is stable and long-lasting.
Claims
1. A phthalocyanine catalytic oxidation method for removing nitrite and its application, It is characterized in that The following steps are involved: (1) preparing a solution, preparing a certain concentration of ammonium phthalocyanine cobalt sulfonate catalyst solution, preparing a certain concentration of sodium nitrite solution as a sample solution to be removed nitrite nitrogen, preparing a certain concentration of p-aminobenzenesulfonic acid solution as a color developer 1, and preparing a certain concentration of naphthylethylenediamine hydrochloride solution as a color developer 2. (2) Ammonium sulfonate cobalt phthalocyanine is used to catalyze oxidation to remove nitrite nitrogen. At room temperature, a certain amount of ammonium sulfonate cobalt phthalocyanine solution is added to a certain amount of sodium nitrite solution, the mixture is evenly mixed and allowed to stand for catalytic oxidation reaction. (3) Spectral analysis: After the above reaction has been in progress for a certain period of time, add a sufficient amount of p-aminobenzenesulfonic acid solution, mix well, and let stand for 5 minutes. Then add a corresponding amount of naphthylethylenediamine hydrochloride solution, add water to make up to 10 mL, mix well, let stand for 15 minutes, and measure the absorbance (A) at 538 nm. The catalyst solution in the above method is added after color development and made up to the volume, and the absorbance A is measured. 0 According to [(A 0 -A) / A 0 ]×100% to calculate the nitrite nitrogen removal rate.
2. The ammonium sulfonate cobalt phthalocyanine according to claim 1 is tetrasulfonate cobalt phthalocyanine or hexasulfonate binuclear cobalt phthalocyanine. Tetrasulfonate cobalt phthalocyanine has a better effect in removing nitrite nitrogen.
3. According to claim 1, the concentration of the ammonium sulfonate phthalocyanine cobalt solution used in the laboratory is 0.5 mg / mL, and the concentration used in the simulated removal of nitrite nitrogen from water is 3.25×10 -4 mg / mL.
4. The temperature for removing nitrite nitrogen according to claim 1 is room temperature, which is the laboratory experimental temperature and has a certain range of variation, varying by about 5°C around 25°C.
5. The catalytic oxidation according to claim 1 is to oxidize the oxygen in the water without adding an external oxidant. In the presence of a catalyst, the oxygen in the water can oxidize the nitrite nitrogen.
6. The catalyst for removing nitrite-nitrogen according to claim 1, ammonium sulfonate phthalocyanine cobalt, is stable in water and can be stored for more than 10 days without significant changes in its catalytic effect.