Aluminum-based ozone heterogeneous catalyst as well as preparation method and application thereof

Abstract

The invention provides an aluminum-based ozone heterogeneous catalyst as well as a preparation method and application thereof, and belongs to the technical field of wastewater treatment. The aluminum-based ozone heterogeneous catalyst is prepared from the following raw materials in parts by weight: 70-80 parts of an aluminum source compound, 5-10 parts of a binder, 5-10 parts of a pore forming agent, 1-5 parts of an auxiliary agent and 8-12 parts of an active component. According to the aluminum-based ozone heterogeneous catalyst disclosed by the invention, the active components are uniformly distributed in the catalyst, and the synergistic effect among the active components catalyzes ozone oxidation, so that the ozone oxidation catalysis efficiency of the catalyst is greatly improved, and the ozone utilization rate in a whole reaction system is improved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to an aluminum-based ozone heterogeneous catalyst, its preparation method, and its application. Background Technology

[0002] With increasingly stringent standards for wastewater treatment plant effluent, membrane treatment processes are frequently incorporated to ensure effluent quality meets these standards. While membrane treatment processes offer high efficiency, they do not remove organic pollutants at the source, resulting in membrane concentrate with high organic content. Compared to conventional industrial wastewater, RO membrane concentrate is characterized by a greater variety of organic compounds, higher concentrations, higher salt content, and greater treatment challenges. In RO membrane concentrate treatment, evaporation and crystallization are inherently energy-intensive, and the complex composition of the organic matter after evaporation can affect salt recovery. Therefore, finding efficient methods to treat organic pollutants in RO membrane concentrate has become a hot topic in industrial applications.

[0003] Ozone, a component of ozone oxidation technology, possesses a high redox potential and strong redox capacity, offering advantages such as high efficiency in treating organic matter, small footprint, simple operation, and no secondary pollution, making it widely used in wastewater treatment. However, the reaction between ozone and organic matter exhibits selectivity, with a lower reaction rate with certain organic compounds, leading to incomplete mineralization. To address this issue, a heterogeneous ozone catalyst is added to the ozone oxidation system to catalyze the decomposition of ozone into more reactive oxygen species with higher oxidizing power.

[0004] Heterogeneous catalysts mainly consist of two parts: a support and an active component. The support primarily determines the physical properties of the catalyst, while the active component is closely related to the catalyst's ozone-catalyzing activity. Chinese invention patent application CN105618080 A discloses a method for preparing a heterogeneous catalyst for treating reverse osmosis concentrate, in which one or more active components are loaded onto the surface of an alumina support, achieving efficient wastewater treatment. Chinese invention patent application CN105771968A discloses a method for preparing an aluminum-based catalyst, mainly by loading multiple active components onto the surface of a support, reducing the catalyst's manufacturing cost. However, due to the complexity of organic matter in wastewater, the active component is affected by the type and content of organic matter in the wastewater. Chinese invention patent application CN120094597 A discloses a formulation for preparing an aluminum-based catalyst suitable for engineering applications, using petrochemical wastewater as the treatment target and combining analysis of the types and contents of organic matter.

[0005] Therefore, it is of great significance to provide an aluminum-based heterogeneous ozone catalyst with high ozone catalytic oxidation efficiency, good catalyst stability, simple preparation process, and low cost. Summary of the Invention

[0006] The purpose of this invention is to provide an aluminum-based heterogeneous ozone catalyst, its preparation method, and its application, in order to solve the technical problems of low ozone catalytic oxidation efficiency, lack of catalyst specificity, complex RO concentrate quality, high treatment difficulty, and high cost in the prior art.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides an aluminum-based heterogeneous ozone catalyst, prepared from raw materials comprising the following parts by weight: 70-80 parts of aluminum source compound, 5-10 parts of adhesive 5-10 parts of pore-forming agent, 1-5 parts of auxiliary agent 8-12 parts of active ingredient.

[0008] Furthermore, the aluminum source compound includes one or more of aluminum hydroxide, boehmite, aluminum nitrate, and aluminum alkoxides.

[0009] Furthermore, the adhesive includes one or more of polyvinyl alcohol, polyethylene glycol, and methylcellulose.

[0010] Furthermore, the pore-forming agent includes one or more of starch, carbon powder, and polymer microspheres.

[0011] Furthermore, the additives include peptizing agents, surfactants, plasticizers, and alkali metal oxides; The colloidal solvent includes nitric acid and / or acetic acid; The surfactant includes hexadecyltrimethylammonium bromide and / or block copolymers; The plasticizer includes one or more of glycerol, polyvinyl alcohol, and citric acid; The alkali metal oxides include one or more of sodium oxide, potassium oxide, and lithium oxide.

[0012] Furthermore, the active component includes manganese salt and / or cerium salt; The manganese salt includes one or more of manganese nitrate, manganese acetate, and manganese chloride, and the cerium salt includes one or more of cerium nitrate, cerium acetate, and cerium chloride.

[0013] This invention provides a method for preparing the aforementioned aluminum-based heterogeneous ozone catalyst, comprising the following steps: 1) The aluminum source compound, binder, pore-forming agent, additives and active components are mixed and then granulated to obtain raw material balls; 2) The raw material pellets were calcined to obtain an aluminum-based ozone heterogeneous catalyst.

[0014] Furthermore, the particle size of the raw material balls is 4~8mm.

[0015] Furthermore, the calcination temperature is 600~700℃, the calcination time is 5~6h, and the calcination heating rate is 5~10℃ / min.

[0016] The present invention also provides an application of the aluminum-based ozone heterogeneous catalyst described above in the advanced treatment of RO concentrate.

[0017] The beneficial effects of this invention are: 1) The manganese-cerium bimetallic supported aluminum-based ozone heterogeneous catalyst prepared in this invention has higher efficiency and more stable treatment efficiency for treating recalcitrant organic pollutants in RO wastewater compared with single-metal catalytic ozone oxidation. 2) The active components of the present invention are uniformly distributed inside the catalyst, and can catalyze ozone oxidation through the synergistic effect between the active components, which greatly increases the efficiency of the catalyst in catalyzing ozone oxidation, improves the ozone utilization rate in the entire reaction system, and reduces the problem of loss or shedding of active components on the surface of heterogeneous catalysts. 3) The aluminum-based ozone heterogeneous catalyst of the present invention has a simple preparation method and a simple preparation process. The raw materials for catalyst production are inexpensive and are currently being produced in large quantities in industry, making it suitable for engineering applications. Attached Figure Description

[0018] Figure 1 The results of the pilot test of catalytic ozone oxidation of RO concentrate wastewater by the catalyst of this invention are shown in the left figure, which shows the COD of the influent and effluent of ozone oxidation and heterogeneous catalytic ozone oxidation, and the COD removal rate and O / C ratio of ozone oxidation and heterogeneous catalytic ozone oxidation. Figure 2 This is a comparison chart of the effluent COD and COD removal rate between the heterogeneous catalyst of this invention and a commercially available catalyst. Detailed Implementation

[0019] This invention provides an aluminum-based heterogeneous ozone catalyst, prepared from raw materials comprising the following parts by weight: 70-80 parts of aluminum source compound, 5-10 parts of adhesive 5-10 parts of pore-forming agent, 1-5 parts of auxiliary agent 8-12 parts of active ingredient.

[0020] In this invention, the content of the aluminum source compound is preferably 70-78 parts by weight, and more preferably 70-75 parts by weight.

[0021] In this invention, the aluminum source compound includes one or more of aluminum hydroxide, boehmite, aluminum nitrate and aluminum alkoxide, preferably one or more of aluminum hydroxide, aluminum nitrate and aluminum alkoxide, and more preferably aluminum hydroxide and / or aluminum nitrate.

[0022] In this invention, the content of the adhesive is preferably 6 to 9 parts by weight, and more preferably 7 to 8 parts by weight.

[0023] In this invention, the adhesive comprises one or more of polyvinyl alcohol, polyethylene glycol, and methylcellulose, preferably polyvinyl alcohol and / or polyethylene glycol, and more preferably polyethylene glycol.

[0024] In this invention, the content of the pore-forming agent is preferably 6 to 9 parts by weight, and more preferably 7 to 8 parts by weight.

[0025] In this invention, the pore-forming agent includes one or more of starch, toner, and polymer microspheres, preferably starch and / or toner.

[0026] In this invention, the content of the auxiliary agent is preferably 2 to 4 parts by weight, and more preferably 3 parts.

[0027] In this invention, the additives include peptizing agents, surfactants, plasticizers, and alkali metal oxides; The colloidal solvent includes nitric acid and / or acetic acid, preferably nitric acid; The surfactant includes hexadecyltrimethylammonium bromide (CTAB) and / or block copolymers (E... P E (preferably cetyltrimethylammonium bromide (CTAB)); The plasticizer includes one or more of glycerol, polyvinyl alcohol and citric acid, preferably glycerol and / or polyvinyl alcohol, and more preferably polyvinyl alcohol; The alkali metal oxide includes one or more of sodium oxide, potassium oxide and lithium oxide, preferably potassium oxide and / or sodium oxide, and more preferably sodium oxide.

[0028] In this invention, the content of the active component is preferably 9 to 11 parts by weight, and more preferably 10 parts by weight.

[0029] In this invention, the active component includes manganese salt and / or cerium salt; The manganese salt includes one or more of manganese nitrate, manganese acetate, and manganese chloride, preferably manganese nitrate and / or manganese acetate, and more preferably manganese nitrate; the cerium salt includes one or more of cerium nitrate, cerium acetate, and cerium chloride, preferably cerium nitrate and / or cerium acetate, and more preferably cerium nitrate.

[0030] In this invention, the mass ratio of manganese salt to cerium salt is 0~10:10~0, preferably 1~9:1~9, and more preferably 2~8:2~8.

[0031] In this invention, the electron transfer generated by the redox reaction between manganese (II) / Mn(III) and Mn(III) / Mn(IV), as well as the oxygen migration inside the oxide lattice oxygen, are all conducive to the catalytic ozone reaction. Cerium itself has special electronic orbitals and Ce(III) / Ce(IV) redox pairs, which allow oxygen vacancies on the surface of cerium oxide to store and release oxygen, ensuring the electron transfer efficiency on the catalyst surface, thereby enhancing the conversion of ozone into active oxygen.

[0032] This invention provides a method for preparing the aforementioned aluminum-based heterogeneous ozone catalyst, comprising the following steps: 1) The aluminum source compound, binder, pore-forming agent, additives and active components are mixed and then granulated to obtain raw material balls; 2) The raw material pellets were calcined to obtain an aluminum-based ozone heterogeneous catalyst.

[0033] In this invention, the particle size of the raw material balls is 4-8 mm, preferably 5-7 mm, and more preferably 6 mm.

[0034] In this invention, the calcination temperature is 600~700℃, preferably 620~680℃, and more preferably 650℃; the calcination time is 5~6h, preferably 5.2~5.8h, and more preferably 5.4~5.6h; the calcination heating rate is 5~10℃ / min, preferably 6~9℃ / min, and more preferably 7~8℃ / min.

[0035] The present invention also provides an application of the aluminum-based ozone heterogeneous catalyst described above in the advanced treatment of RO concentrate.

[0036] In this invention, the method of using aluminum-based ozone heterogeneous catalyst in the deep treatment of RO concentrate is as follows: After adding aluminum-based ozone heterogeneous catalyst to RO concentrate, ozone is introduced at a rate of 40-80 mg / L. Samples are taken periodically for analysis. After the reaction is completed, the ozone is turned off, and the COD of samples taken at different times is measured. The catalytic ozone oxidation efficiency of the catalyst is compared by the COD removal rate.

[0037] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0038] Examples 1-11

[0039] 70 parts aluminum hydroxide, 10 parts polyethylene glycol, 5 parts starch, 5 parts sodium oxide, and 10 parts active ingredient (Mn in Examples 1-11) were mixed. 2+ Ce 3+ The mass ratios were 10:0, 9:1, 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8, 1:9, and 0:10, respectively. After mixing, the mixture was granulated to obtain raw material balls with a particle size of 6 mm. The temperature was increased to 650℃ at a heating rate of 5℃ / min, and then the raw material pellets were calcined at high temperature for 6 hours. After calcination, the pellets were allowed to stand and cool to obtain an aluminum-based ozone heterogeneous catalyst.

[0040] The aluminum-based heterogeneous ozone catalysts prepared in Examples 1-11 were used to conduct heterogeneous catalytic ozone oxidation experiments. The method was as follows: Aluminum-based heterogeneous ozone catalysts were added to RO concentrate (the basic water quality of the RO concentrate is shown in Table 1), and then ozone was introduced at a rate of 60 mg / L. Samples were taken periodically for analysis. After the reaction was completed, the ozone was turned off, and the COD of samples taken at different times was measured. The catalytic ozone oxidation efficiency of the catalyst was compared by the COD removal rate. The experimental results are shown in Table 2.

[0041] Table 1. Basic water quality of RO concentrate in the embodiments of the present invention.

[0042] Table 2. Experimental results of catalytic ozone oxidation treatment of RO concentrate with different proportions of active components in Examples 1-11.

[0043] As shown in Table 2, the catalytic efficiency first increases and then decreases with the increase of the proportion of cerium, which proves that the catalyst with a mass ratio of manganese to cerium of 5:5 has the fastest electron transfer rate, the highest ozone catalytic efficiency, and a COD removal rate of 74.71%.

[0044] The treatment efficiency of the optimal aluminum-based heterogeneous ozone catalyst prepared in Examples 1-11 for catalytic ozone oxidation of RO concentrate was tested. During the pilot-scale test, the influent COD results were as follows: Figure 1As shown, the system operated continuously for 31 days under the conditions of ozone dosage of 90 mg / L, catalyst packing thickness of 20 cm, residence time of 60 min, and reflux ratio of 150%. The experimental results showed that the COD of the influent was higher than 80 mg / L, while the COD of the treated RO wastewater effluent was lower than 30 mg / L, with COD removal rates exceeding 70% and O / C ratios between 1.3 and 1.5. In contrast, the COD removal rate of ozone oxidation alone was only 30-35%, and the ozone utilization rate was 3.0-4.5 (ΔO3 / ΔCOD represents the amount of COD removed by a unit of ozone; the lower the value, the better the wastewater treatment effect within the reaction system). This demonstrates that the addition of the heterogeneous ozone catalyst significantly improved ozone utilization under the same conditions. The pilot-scale heterogeneous catalytic ozone oxidation system showed stable treatment effects on RO concentrate wastewater, and the effluent quality met all wastewater discharge standards.

[0045] The organic matter and its relative proportion in the influent and effluent are shown in Tables 3 and 4. The influent contains 100 kinds of organic matter, among which the organic matter with the largest proportion is 2-methyl-undecane, dodecane, 5-propyl-nonane, 2,5-dimethyl-decadecane, and 2,6,11,15-tetramethyl-hexadecane. Considering that the influent of the small-scale test has been biochemically treated, these pollutants are all non-biodegradable organic pollutants. After the wastewater is treated by the heterogeneous catalyst catalytic ozone reaction, the organic pollutants in the wastewater change. The effluent contains 37 kinds of organic matter, among which short-chain organic matter disappears, and long-chain organic matter is broken down to generate small molecule organic matter. This proves that the hydroxyl radicals generated in the catalytic ozone oxidation system can remove organic matter in water, and the generated hydroxyl radicals can effectively reduce the COD value of water. The effluent can meet the discharge standards, and the remaining organic matter in the effluent provides the remaining COD in the effluent.

[0046] Table 3. Types and contents of organic matter in the influent of RO wastewater in a small-scale test.

[0047] Table 4. Types and contents of organic matter in the influent of RO wastewater in a small-scale test.

[0048] Tables 3 and 4 show that the types and quantities of organic pollutants in the water changed before and after the reaction. The presence of the same substance indicates that the substance was not degraded. The different proportions are because the types of organic matter in the water changed, resulting in different proportions.

[0049] Comparative Examples 1-4

[0050] The catalysts are heterogeneous ozone catalysts purchased from Jiangxi Huihua Technology Co., Ltd. (catalyst 1), Shandong Senyang Environmental Technology Co., Ltd. (catalyst 2), Henan Haoquan Water Treatment Materials Co., Ltd. (catalyst 3), and Wuxi Kaixi Catalyst Co., Ltd. (catalyst 4).

[0051] The heterogeneous ozone catalysts of Comparative Examples 1-4 and Example 6 were used for catalytic ozone oxidation treatment of RO concentrate wastewater. When the inlet ozone concentration was 40 mg / L, the inlet flow rate was 0.2 L / min, the catalyst loading was 50 g / L, and the effective volume of the reaction column in the small-scale test was 3 L, the experimental results are as follows: Figure 2 As shown.

[0052] Depend on Figure 2 It can be seen that the heterogeneous catalyst prepared by this invention has a much higher efficiency in catalyzing ozone than commercially available catalysts.

[0053] As can be seen from the above embodiments, the present invention provides an aluminum-based heterogeneous ozone catalyst, its preparation method, and its application. The aluminum-based heterogeneous ozone catalyst of the present invention is prepared from raw materials comprising the following parts by weight: 70-80 parts of aluminum source compound, 5-10 parts of binder, 5-10 parts of pore-forming agent, 1-5 parts of additive, and 8-12 parts of active component. The aluminum-based heterogeneous ozone catalyst of the present invention significantly increases the catalytic ozone oxidation efficiency and improves the ozone utilization rate in the entire reaction system through the uniform distribution of active components within the catalyst and the synergistic effect between the active components.

[0054] The above description is only a preferred embodiment 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. An aluminum-based heterogeneous ozone catalyst, characterized in that, It is prepared from raw materials comprising the following parts by weight: 70-80 parts of aluminum source compound, 5-10 parts of adhesive 5-10 parts of pore-forming agent, 1-5 parts of auxiliary agent 8-12 parts of active ingredient.

2. The aluminum-based ozone heterogeneous catalyst according to claim 1, characterized in that, The aluminum source compound includes one or more of aluminum hydroxide, boehmite, aluminum nitrate, and aluminum alkoxides.

3. The aluminum-based ozone heterogeneous catalyst according to claim 1 or 2, characterized in that, The adhesive includes one or more of polyvinyl alcohol, polyethylene glycol, and methylcellulose.

4. The aluminum-based ozone heterogeneous catalyst according to claim 3, characterized in that, The pore-forming agent includes one or more of starch, carbon powder, and polymer microspheres.

5. The aluminum-based ozone heterogeneous catalyst according to claim 4, characterized in that, The additives include peptizing agents, surfactants, plasticizers, and alkali metal oxides; The colloidal solvent includes nitric acid and / or acetic acid; The surfactant includes hexadecyltrimethylammonium bromide and / or block copolymers; The plasticizer includes one or more of glycerol, polyvinyl alcohol, and citric acid; The alkali metal oxides include one or more of sodium oxide, potassium oxide, and lithium oxide.

6. The aluminum-based ozone heterogeneous catalyst according to claim 4 or 5, characterized in that, The active components include manganese salts and / or cerium salts; The manganese salt includes one or more of manganese nitrate, manganese acetate, and manganese chloride, and the cerium salt includes one or more of cerium nitrate, cerium acetate, and cerium chloride.

7. A method for preparing an aluminum-based ozone heterogeneous catalyst according to any one of claims 1 to 6, characterized in that, Includes the following steps: 1) The aluminum source compound, binder, pore-forming agent, additives and active components are mixed and then granulated to obtain raw material balls; 2) The raw material pellets were calcined to obtain an aluminum-based ozone heterogeneous catalyst.

8. The method for preparing the aluminum-based ozone heterogeneous catalyst according to claim 7, characterized in that, The raw material balls have a particle size of 4~8mm.

9. The method for preparing the aluminum-based ozone heterogeneous catalyst according to claim 8, characterized in that, The calcination temperature is 600~700℃, the calcination time is 5~6h, and the calcination heating rate is 5~10℃ / min.

10. The application of the aluminum-based ozone heterogeneous catalyst according to any one of claims 1 to 6 in the advanced treatment of RO concentrate.

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