A high-performance catalyst and its method for recycling high-salt brine of mirabilite

Abstract

The present invention belongs to the field of wastewater treatment technology, and specifically relates to a high-performance catalyst and a method for recovering a high-salt sodium sulfate salt thereof. The preparation method of the high-performance catalyst comprises the following steps: (1) dissolving magnesium salt, iron salt, lanthanum salt and cerium salt in water, and uniformly dispersing them by ultrasonication to obtain an impregnation solution; (2) placing a γ-alumina carrier in the impregnation solution, stirring evenly, and obtaining a precursor solution after standing; (3) drying the precursor solution and calcining it in a muffle furnace, and obtaining a high-performance catalyst after calcination. In the present invention, the active component is loaded onto the surface and interior of the γ-alumina solid phase carrier material in the form of a salt solution by impregnation, and the loaded target element is formed into a catalyst with catalytic activity through processes such as calcination and activation. The present invention solves the problem of low catalytic efficiency of heterogeneous ozone catalysts prepared from single metal oxides in actual wastewater treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and particularly relates to a high-performance catalyst and a method for recovering glauber salt high-salt water using the catalyst. Background Art

[0002] High-salinity wastewater, due to the presence of large amounts of salt and organic pollutants, can have serious impacts on soil, water, and plant and animal ecosystems. For plants and animals, the salt in wastewater disrupts cellular osmotic pressure, inhibiting growth, impacting animal health, and reducing the survival rate of seedlings. Continuous exposure to high-salinity conditions can significantly reduce species abundance. For soil, the use of untreated saline wastewater for irrigation can leave salt residue in the soil, leading to a series of problems such as salinization and depletion of soil resources. Land salinization caused by high-salinity wastewater discharge can also affect plant growth. For water bodies, the discharge of high-salinity wastewater can negatively impact the use of drinking water and other freshwater resources, leading to salinization. The presence of recalcitrant organic pollutants in high-salinity wastewater can also pollute water bodies, affecting the growth and abundance of aquatic organisms, thereby damaging the aquatic ecosystem. Therefore, the treatment of high-salinity wastewater is essential.

[0003] Sodium sulfate (sodium sulfate) is a major component of high-salt wastewater in many industrial processes, such as those in the silica, chemical fiber, metallurgy, and printing and dyeing industries. Discharge of untreated sodium sulfate-rich wastewater into the environment not only results in significant resource waste but also triggers a series of environmental pollution and water shortage issues, severely hindering sustainable development. Consequently, treatment technologies for sodium sulfate-rich wastewater have garnered widespread attention from researchers both domestically and internationally, and research on sulfate-rich wastewater treatment continues to grow.

[0004] Currently, the commonly used methods for treating high-salinity wastewater can be divided into three categories: biological treatment, physical and chemical treatment, and advanced oxidation. In recent years, numerous advanced oxidation technologies have been gradually applied to wastewater treatment, such as ultraviolet-photocatalytic oxidation, electrochemical oxidation, wet chemical oxidation, and heterogeneous ozone oxidation. Among them, heterogeneous catalytic ozone oxidation technology has excellent characteristics such as high mineralization and no secondary pollution. However, issues such as catalyst stability and ozone utilization efficiency have become important factors restricting the further promotion and application of this technology. Heterogeneous catalytic ozone oxidation technology, also known as heterogeneous catalytic ozone oxidation technology, has been widely used in the field of advanced wastewater treatment in recent years due to its advantages such as catalyst recyclability, no secondary pollution, high mineralization of organic pollutants in wastewater, and high ozone utilization efficiency. The addition of a heterogeneous catalyst to ozone oxidation can facilitate the decomposition of ozone and generate free radicals with stronger oxidizing ability, thereby triggering a redox chain reaction. The heterogeneous catalytic process can increase the degradation rate of organic matter. Therefore, it is of great practical and research significance to develop an ozone catalyst that is suitable for various conditions and various process wastewaters, is easy to prepare, and is low-cost, so as to improve the utilization rate and reaction rate of ozone and reduce the COD in the wastewater. Summary of the Invention

[0005] In order to solve the technical problem in the prior art that ozone catalytic oxidation catalysts cannot effectively reduce the COD of wastewater, the present invention provides a high-performance catalyst and a method for recovering sodium sulphate high-salt water.

[0006] A high-performance catalyst, the preparation method of which comprises the following steps:

[0007] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is (8-14): (6-8): (1.5-3): 1;

[0008] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and allow to stand to obtain a precursor solution;

[0009] (3) The precursor solution is dried and then calcined in a muffle furnace at 450-700°C to obtain a high-performance catalyst.

[0010] The use of a carrier to prepare a supported catalyst can greatly improve the catalytic activity of the catalyst. Among the selection of catalysts, carrier materials that are easy to obtain, low in price, stable in nature, and highly corrosion-resistant are most suitable for industrial water treatment. On the one hand, they can reduce the cost and save costs. On the other hand, their strong corrosion resistance can be applied to complex industrial water quality, and their stable properties can increase the number of uses of the catalyst and prevent the dissolution of metal elements from causing secondary pollution of the water body. Supported catalysts mainly utilize the surface properties of the carrier to further improve the catalytic activity of the catalyst in catalytic ozone oxidation; this can increase the specific surface area of the catalyst and increase the active sites of the catalyst. Among them, the present invention uses γ-alumina as a catalyst carrier, which is due to the advantages of γ-alumina having a large specific surface area, high mechanical strength, and controllable surface acidity and alkalinity.

[0011] Heterogeneous ozone catalysts prepared from single metal oxides suffer from acid resistance, easy metal element dissolution, and low catalytic efficiency in actual wastewater treatment. To address these issues, the present invention addresses the microstructure of the elements and prepares a multi-component composite catalyst by adding metal components such as magnesium salts, iron salts, lanthanum salts, and cerium salts.

[0012] Among them, magnesium, as an alkaline earth metal, can be loaded with its oxide MgO, which can change the acid-base properties of the catalyst surface. MgO can also regulate pH in water. When the initial pH of the water is neutral or alkaline, MgO can effectively slow down the pH drop caused by small-molecule organic acids produced by oxidation, thereby ensuring the efficiency of ozone catalysis in producing •OH. When the initial pH of the water is weakly acidic, MgO, as a weakly alkaline substance, can raise the pH to a certain level. Based on this, MgO's role in regulating the pH of the water during the experiment is a key factor in MgO's ozone catalytic effect. The variable valence state and rapid electron transfer characteristics of iron allow the valence state of iron ions to change during ozone catalytic oxidation, thereby achieving electron transfer, thereby improving catalytic activity and ozone catalytic oxidation efficiency.

[0013] Although the active components of the catalysts used in this experiment are all the same four metal oxides: magnesium, iron, lanthanum, and cerium, the catalytic activity of the catalysts prepared with different active component ratios varies significantly. This is because a specific active component ratio significantly enhances the synergistic effect between the active components, promoting the decomposition of ozone and the production of large quantities of strong oxidizing species such as hydroxyl radicals. Under certain compositions, MgO and iron oxides exhibit a strong synergistic catalytic effect. On the one hand, MgO disperses in a specific crystal form around the iron oxide, enhancing the oxygen-cooperating capacity of the iron oxides in different valence states during their mutual conversion, thus facilitating the adsorption of ozone molecules by the catalyst during the ozone oxidation reaction. On the other hand, MgO and iron oxides form specific active centers on the catalyst surface. These active centers provide a large number of oxidative sites, promoting the decomposition of ozone, accelerating electron transfer, and promoting the continuous production of hydroxyl radicals through a free radical chain reaction. The presence of a large number of hydroxyl radicals accelerates the oxidative degradation of organic matter and improves the removal rate of COD in water. On the other hand, the addition of lanthanum and cerium salts improves the dispersion of metal oxides on the γ-alumina support surface, increasing the catalyst's specific surface area and significantly enhancing catalytic activity. The lanthanum salt, which has a smaller atomic radius, should be used in greater amounts than the cerium salt to further improve the dispersion of the metal oxide. Furthermore, the mass ratio of magnesium salt, iron salt, lanthanum salt, and cerium salt is (9-12):(6-8):(1.5-3):1. By adjusting the ratio of each element, catalytic efficiency can be further improved.

[0014] To improve metal element utilization, the present invention applies active components in the form of a salt solution to the surface and interior of a γ-alumina solid-phase support material through impregnation. Once impregnation equilibrium is reached, the γ-alumina support is separated from the impregnation solution and, through calcination and other activation processes, the loaded target elements are transformed into a catalytically active catalyst. This impregnation method allows for direct production of the catalyst support, eliminating the catalyst forming step. This significantly reduces the amount of active components used and manufacturing costs, a particularly important aspect for rare metal elements with high catalytic effects.

[0015] Furthermore, the ultrasonic power in step (1) is 200-400W.

[0016] Furthermore, in step (1), the magnesium salt, iron salt, lanthanum salt and cerium salt are respectively selected from magnesium nitrate (Mg(NO3)2), iron nitrate (Fe(NO3)3), lanthanum nitrate (La(NO3)3) and cerium nitrate (Ce(NO3)3).

[0017] Furthermore, in step (2), the average particle size of the γ-alumina carrier is 200-800 nm; and the ratio of the mass of the γ-alumina carrier to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt and cerium salt is (7-10):1.

[0018] Furthermore, in step (2), the stirring rate is 200-400 rpm; and the standing time is 8-12 h.

[0019] Furthermore, in step (3), the drying is carried out in an oven at 70-90° C.; the roasting time is 5-7 h.

[0020] Furthermore, the calcination temperature is 500-600° C. If the calcination temperature is too low, the oxide crystal form may be imperfect; if the calcination temperature is too high, the support structure may collapse, which is not conducive to increasing the surface area.

[0021] In another aspect, the present invention also provides a method for recovering sodium sulphite from sodium sulphite-rich brine using a high-performance catalyst. The process for recovering sodium sulphite from sodium sulphite-rich brine comprises the following steps: first, subjecting the sodium sulphite-rich brine to tubular membrane filtration, acid adjustment and neutralization, spiral membrane ultrafiltration, ozone catalytic oxidation, and nanofiltration membrane separation to produce sodium sulphite nanofiltration concentrate; then, evaporating and crystallizing the sodium sulphite nanofiltration concentrate to obtain the sodium sulphite product; wherein the high-performance catalyst is added to the ozone catalytic oxidation process for catalytic oxidation. Using the catalyst prepared by the present invention in the sodium sulphite recovery process can substantially reduce the COD content in the wastewater and improve the purity of the sodium sulphite product.

[0022] Furthermore, in the ozone catalytic oxidation process, the dosage of the high-performance catalyst is 4-70 g / L, the ozone concentration is 30-70 ppm, and the pH is 8-14.

[0023] Beneficial effects: The present invention loads the active components in the form of salt solution onto the surface and interior of the γ-alumina solid phase carrier material by impregnation, and through processes such as roasting and activation, the loaded target elements are formed into a catalyst with catalytic activity. The catalyst carrier prepared by the impregnation method can be obtained directly, eliminating the step of catalyst molding. Starting from the microstructure of the elements, the present invention prepares a multi-component composite catalyst by adding metal components such as magnesium salts, iron salts, lanthanum salts, and cerium salts. It solves the problems of heterogeneous ozone catalysts prepared from single metal oxides in actual wastewater treatment, such as acid resistance, easy dissolution of metal elements, and low catalytic efficiency. The catalyst prepared by the present invention is used in the recovery process of sodium sulfate, which can fully reduce the COD in wastewater and improve the purity of sodium sulfate products. DETAILED DESCRIPTION

[0024] The present invention will be explained in more detail below through specific embodiments. However, it should be understood that the specific functional details disclosed in this specification should not be interpreted as limiting, but only as the basis for the claims and as a representative basis for teaching those skilled in the art to employ the present invention in different ways in virtually any appropriate detailed embodiment.

[0025] Example 1

[0026] A high-performance catalyst, the preparation method of which comprises the following steps:

[0027] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 9:6:1.5:1; the ultrasonic power is 200W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0028] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 7:1; the stirring rate is 200 rpm; and the standing time is 8 hours;

[0029] (3) The precursor solution is dried and then calcined in a muffle furnace at 500°C to obtain a high-performance catalyst; the drying is carried out in an oven at 70°C; the calcination time is 7h.

[0030] Example 2

[0031] A high-performance catalyst, the preparation method of which comprises the following steps:

[0032] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonic dispersion to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 12:8:3:1; the ultrasonic power is 400W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0033] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 10:1; the stirring rate is 400 rpm; and the standing time is 12 h;

[0034] (3) The precursor solution is dried and calcined in a muffle furnace at 600°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 90°C; the calcination time is 5 hours.

[0035] Example 3

[0036] A high-performance catalyst, the preparation method of which comprises the following steps:

[0037] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 9:8:1.5:1; the ultrasonic power is 200W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0038] (2) The γ-alumina support was placed in the impregnation solution, stirred evenly, and allowed to stand to obtain a precursor solution; the average particle size of the γ-alumina support was 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt was 10:1; the stirring rate was 200 rpm; and the standing time was 10.5 h;

[0039] (3) The precursor solution was dried and then calcined in a muffle furnace at 600°C to obtain a high-performance catalyst; the precursor solution was dried in an oven at 90°C for 5.2 hours.

[0040] Example 4

[0041] A high-performance catalyst, the preparation method of which comprises the following steps:

[0042] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 9.5:6.5:2:1; the ultrasonic power is 250W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0043] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 250 rpm; and the standing time is 9 hours;

[0044] (3) The precursor solution was dried and calcined in a muffle furnace at 520°C to obtain a high-performance catalyst. The solution was dried in an oven at 75°C for 6.2 h.

[0045] Example 5

[0046] A high-performance catalyst, the preparation method of which comprises the following steps:

[0047] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 11:7.5:2.6:1; the ultrasonic power is 350W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0048] (2) The γ-alumina support was placed in the impregnation solution, stirred evenly, and allowed to stand to obtain a precursor solution; the average particle size of the γ-alumina support was 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt was 9:1; the stirring rate was 350 rpm; and the standing time was 11 h;

[0049] (3) The precursor solution was dried and calcined in a muffle furnace at 580°C to obtain a high-performance catalyst; the precursor solution was dried in an oven at 85°C for 5.6 hours.

[0050] Example 6

[0051] A high-performance catalyst, the preparation method of which comprises the following steps:

[0052] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 10:7:2:1; the ultrasonic power is 300W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0053] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 300 rpm; and the standing time is 10 h;

[0054] (3) The precursor solution is dried and then calcined in a muffle furnace at 450°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 80°C; the calcination time is 6 hours.

[0055] Example 7

[0056] A high-performance catalyst, the preparation method of which comprises the following steps:

[0057] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 10:7:2:1; the ultrasonic power is 300W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0058] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 300 rpm; and the standing time is 10 h;

[0059] (3) The precursor solution is dried and then calcined in a muffle furnace at 700°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 80°C; the calcination time is 6 hours.

[0060] Example 8

[0061] A high-performance catalyst, the preparation method of which comprises the following steps:

[0062] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonic dispersion to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 8:7:2:1; the ultrasonic power is 300W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0063] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 300 rpm; and the standing time is 10 h;

[0064] (3) The precursor solution is dried and calcined in a muffle furnace at 550°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 80°C for 6 hours.

[0065] Example 9

[0066] A high-performance catalyst, the preparation method of which comprises the following steps:

[0067] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 14:7:2:1; the ultrasonic power is 300W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0068] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 300 rpm; and the standing time is 10 h;

[0069] (3) The precursor solution is dried and calcined in a muffle furnace at 550°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 80°C for 6 hours.

[0070] Example 10

[0071] A high-performance catalyst, the preparation method of which comprises the following steps:

[0072] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 10:7:2:1; the ultrasonic power is 300W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0073] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 300 rpm; and the standing time is 10 h;

[0074] (3) The precursor solution is dried and calcined in a muffle furnace at 550°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 80°C for 6 hours.

[0075] Comparative Example 1

[0076] A high-performance catalyst, the preparation method of which comprises the following steps:

[0077] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonic dispersion to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 0:14:4:2; the ultrasonic power is 300W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of cerium nitrate in the impregnation solution is 0.3wt%;

[0078] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 300 rpm; and the standing time is 10 h;

[0079] (3) The precursor solution is dried and calcined in a muffle furnace at 550°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 80°C for 6 hours.

[0080] Comparative Example 2

[0081] A high-performance catalyst, the preparation method of which comprises the following steps:

[0082] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonic dispersion to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 15.4:0:3.1:1.5; the ultrasonic power is 300W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0083] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 300 rpm; and the standing time is 10 h;

[0084] (3) The precursor solution is dried and calcined in a muffle furnace at 550°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 80°C for 6 hours.

[0085] Comparative Example 3

[0086] A high-performance catalyst, the preparation method of which comprises the following steps:

[0087] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 11.8:8.2:0:0; the ultrasonic power is 300W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0088] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 300 rpm; and the standing time is 10 h;

[0089] (3) The precursor solution is dried and calcined in a muffle furnace at 550°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 80°C for 6 hours.

[0090] Comparative Example 4

[0091] A high-performance catalyst, the preparation method of which comprises the following steps:

[0092] (1) Dissolve magnesium salt, iron salt, lanthanum salt and cerium salt in water and disperse them uniformly by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 10:7:1:2; the ultrasonic power is 300W; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; the concentration of magnesium nitrate in the impregnation solution is 3wt%;

[0093] (2) Place the γ-alumina support in the impregnation solution, stir evenly, and let it stand to obtain a precursor solution; the average particle size of the γ-alumina support is 500 nm; the ratio of the mass of the γ-alumina support to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the stirring rate is 300 rpm; and the standing time is 10 h;

[0094] (3) The precursor solution is dried and calcined in a muffle furnace at 550°C to obtain a high-performance catalyst; the precursor solution is dried in an oven at 80°C for 6 hours.

[0095] Performance testing:

[0096] BET analysis and catalytic performance analysis were performed on the high-performance catalysts prepared in Examples 1-10 and Comparative Examples 1-4. Using sodium sulfate high-salt wastewater as the raw material, the COD degradation rate in the wastewater was tested using an ozone catalytic oxidation system with a high-performance catalyst dosage of 5 g / L, an ozone concentration of 40 ppm, and a solution pH of 10 for a reaction time of 75 minutes.

[0097] The sodium sulfate high-salt brine was sequentially subjected to tubular membrane filtration, acid adjustment and neutralization, spiral membrane ultrafiltration, ozone catalytic oxidation, and nanofiltration membrane separation processes to produce sodium sulfate nanofiltration concentrate. The sodium sulfate nanofiltration concentrate was then evaporated and crystallized to obtain the sodium sulfate product, and the sodium sulfate purity was tested. The ozone catalytic oxidation process was performed using the high-performance catalysts prepared in Examples 1-10 and Comparative Examples 1-4, respectively, at a dosage of 45 g / L, an ozone concentration of 60 ppm, and a solution pH of 10. The test results are shown in Table 1.

[0098]

[0099]

[0100] As can be seen from Table 1, the present invention loads the active component in the form of a salt solution onto the surface and interior of a γ-alumina solid support material by impregnation, and through processes such as roasting and activation, the loaded target element forms a catalyst with catalytic activity. The catalyst carrier prepared by the impregnation method can be directly obtained, eliminating the step of catalyst molding. Starting from the microstructure of the elements, the present invention prepares a multi-component composite catalyst by adding metal components such as magnesium salts, iron salts, lanthanum salts, and cerium salts. It solves the problems of heterogeneous ozone catalysts prepared from single metal oxides in actual wastewater treatment, such as acid resistance, easy dissolution of metal elements, and low catalytic efficiency. The catalyst prepared by the present invention is used in the recovery process of sodium sulfate, which can fully reduce the COD in wastewater and improve the purity of sodium sulfate products. Specifically, it can be seen from Example 10 and Comparative Examples 1-3 that magnesium salts, iron salts and rare earth elements in a specific ratio can play a synergistic role. On the one hand, MgO will be dispersed around the iron oxide in a certain crystal form, improving the oxygen-cooperating ability of iron oxides of different valence states in the process of mutual conversion, which is beneficial to the adsorption of ozone molecules by the catalyst in the catalytic ozone oxidation reaction; on the other hand, MgO and iron oxide will form specific active centers on the catalyst surface. These active centers can provide a large number of oxidative active sites, which will promote the decomposition of ozone, accelerate the transfer of electrons, and promote the continuous production of hydroxyl radicals by free radical chain reactions. The presence of a large number of hydroxyl radicals accelerates the oxidative degradation of organic matter and improves the removal rate of COD in water. On the other hand, the addition of lanthanum salts and cerium salts improves the dispersion of metal oxides on the surface of the γ-alumina carrier, which can increase the specific surface area of the catalyst and greatly improve the catalytic activity. As can be seen from Comparative Example 4, the amount of lanthanum salt with a smaller atomic radius should be more than that of cerium salt to better improve the dispersion of metal oxides.

[0101] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0102] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A high performance catalyst, characterized in that: The preparation method comprises the following steps: (1) dissolving magnesium salt, iron salt, lanthanum salt and cerium salt in water and uniformly dispersing by ultrasonication to obtain an impregnation solution; the mass ratio of magnesium salt, iron salt, lanthanum salt and cerium salt is 10:7:2:1; the magnesium salt, iron salt, lanthanum salt and cerium salt are selected from magnesium nitrate, iron nitrate, lanthanum nitrate and cerium nitrate respectively; (2) placing the γ-alumina carrier in the impregnation solution, stirring evenly, and allowing to stand to obtain a precursor solution; the ratio of the mass of the γ-alumina carrier to the sum of the mass of the four salts of magnesium salt, iron salt, lanthanum salt, and cerium salt is 8:1; the average particle size of the γ-alumina carrier is 200-800 nm; (3) The precursor solution is dried and then calcined in a muffle furnace at 550°C to obtain a high-performance catalyst.

2. The high performance catalyst according to claim 1, characterized in that The ultrasonic power in step (1) is 200-400W.

3. The high performance catalyst according to claim 1, characterized in that In step (2), the stirring rate is 200-400 rpm; and the standing time is 8-12 h.

4. The high performance catalyst according to claim 1, characterized in that In step (3), the drying is carried out in an oven at 70-90°C; the roasting time is 5-7h.

5. A method for recovering glauber salt high-salt water using the high-performance catalyst according to any one of claims 1 to 4, characterized in that: The following steps are involved: First, the sodium sulphate high-salt water is sequentially filtered through a tubular membrane, acidified for neutralization, a spiral membrane ultrafiltration, ozone catalytic oxidation, and a nanofiltration membrane separation process to obtain sodium sulphate nanofiltration concentrated water; then, the sodium sulphate nanofiltration concentrated water is evaporated and crystallized to obtain the product sodium sulphate; wherein, the ozone catalytic oxidation process is added with the high-performance catalyst for catalytic oxidation.

6. The method for recovering glauber salt high-salt water using the high-performance catalyst as claimed in claim 5, wherein: In the ozone catalytic oxidation process, the dosage of the high-performance catalyst is 4-70 g / L, the ozone concentration is 30-70 ppm, and the pH is 8-14.

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