Device for degrading COD (Chemical Oxygen Demand), use method of device, catalyst, preparation method of catalyst and application of catalyst

Abstract

The invention provides a device for degrading COD (Chemical Oxygen Demand), a use method of the device, a catalyst, a preparation method of the catalyst and application of the catalyst, and solves the problems of large occupied area, poor COD removal effect under a high-salt condition and overlong reaction time of a COD removal device in current practical engineering. According to the invention, multi-stage adsorption and catalytic in-situ degradation are combined with a multifunctional adsorption catalytic reaction and a multi-stage advanced oxidation technology. According to the catalyst, coal gangue and / or gasification slag and carbon and ferric oxide of fly ash are subjected to an in-situ oxidation-reduction reaction, a multivalent multi-scale catalyst material is prepared, and additional catalyst raw materials and a complex preparation process are not needed. The device for degrading COD comprises an advanced oxidation in-situ reaction unit, an ozone aeration adding unit, an oxidizing agent and acid-base adding unit, a mixing unit, a produced water recycling unit and a control unit.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial wastewater treatment, and specifically relates to a device for degrading COD, a use method thereof, a catalyst, and a preparation method and application thereof. Background Art

[0002] Mine brine is the concentrated brine produced by the mine water produced during coal mining after desalination and reverse osmosis treatment. In 2019, the amount of mine water produced in my country was about 7.1 billion m 3 , and among them Na + , Ca 2+ , Cl - 、SO4 2- Plasma mass concentration is as high as 1000mg / L-4000mg / L, and even exceeds 40000mg / L in some cases. Direct discharge will cause surface water pollution (increased salt content), soil salinization, reduction of surface vegetation, shallow surface groundwater pollution and other hazards to the ecological environment. In addition, more than 70% of my country's coal resources are distributed in water-scarce provinces such as Shanxi, Shaanxi, Xinjiang and Inner Mongolia. If the mine water generated by a large amount of coal mining activities is not treated and recycled in time, the water shortage in these areas will be further aggravated.

[0003] At present, the mine water treatment process built in the Inner Mongolia-Shaanxi region mainly includes three links: desalination, secondary concentration and evaporation crystallization salt separation; among them, the core process of desalination and secondary concentration is the use of reverse osmosis concentration technology, and the auxiliary process includes pre-treatment processes such as hardness removal and impurity removal to meet the reverse osmosis water inlet requirements. In the actual operation of the project, the impurities and chemical oxygen demand (COD) content in the concentrated brine after the mine water is concentrated by two-stage reverse osmosis is high, which in turn affects the stability of the subsequent evaporation crystallization process and the quality of the crystallized salt. Therefore, effective means must be taken before evaporation crystallization to partially remove the COD in the concentrated brine after reverse osmosis concentration.

[0004] Advanced Oxidation Process (AOP) is commonly used in the current industry to degrade COD in high-salt wastewater. However, the traditional Fenton advanced oxidation process will not only be accompanied by the formation of iron sludge during the COD degradation process, which is not conducive to the subsequent evaporation equipment operation and the quality of crystallized salt, but also in actual engineering applications, there are problems such as the short half-life of oxygen-active substances in the reaction process, such as hydroxyl radicals, and low redox potential, resulting in poor COD removal effect.

[0005] Chinese patent CN110342740B discloses a purification method and purification system for salt-containing organic wastewater, wherein the wastewater produced in the pre-treatment process is subjected to membrane separation and concentration to obtain concentrated product water and recyclable reused water; the concentrated product water is subjected to organic separation treatment to obtain separated wastewater; the pH of the separated wastewater is adjusted to acidic, and then subjected to Fenton oxidation treatment to obtain pre-oxidation product water; after adjusting the pH of the pre-oxidation product water, a biochemical oxidation treatment is performed to obtain biochemical product water, which is then mixed with the salt-containing organic wastewater for recycling. However, in actual engineering applications, the concentrated solution after membrane separation and concentration has a high salt content, and the treatment effect is not ideal.

[0006] Chinese patent application CN113562903A provides a multi-cycle oxidation device and treatment process for high-salinity and refractory COD wastewater treatment, in which catalyst and hydrogen peroxide are added to the wastewater, which flows into the reaction tank, stays in the first reaction tank for 10min-1.5h, stays in the second reaction tank for 10min-1.5h, and finally neutralizes in the neutralization tank, and flows into the sedimentation tank after pH adjustment. In actual engineering applications, there are problems such as multiple tanks, complex processes, high investment, and poor treatment effects.

[0007] Chinese patent CN107500456B discloses a device and method for treating high COD wastewater using a composite advanced oxidation process, the device includes a hydrogen peroxide catalytic treatment unit, an ozone catalytic oxidation treatment unit, an ozone generator, and a waste gas processor. The ultraviolet lamp used has a short lifespan and poor light transmittance in the wastewater, which affects the operating efficiency and stability of the system; the ultraviolet lamp generates severe heat, and the additional temperature control system increases the complexity and energy consumption of the device; and there are many process devices, which easily causes unstable operation of the device.

[0008] In actual industrial wastewater zero-discharge projects, after secondary reverse osmosis concentration, the TDS (total dissolved solids) is greater than 50g / L. Ozone + hydrogen peroxide or ozone + metal catalysts are often used for COD degradation treatment. The COD removal device occupies a large area and the reaction time is too long. In the actual treatment process, the cost of metal catalysts is relatively high, and the catalysts are mostly fixed at the bottom of the reaction device, resulting in particulate matter in the wastewater and catalytic reaction products being deposited on the catalyst surface, affecting the effect of the catalyst in degrading COD. The COD degradation rate does not exceed 50%. Summary of the invention

[0009] The purpose of the present invention is to solve the problems in current practical projects such as high catalyst cost, large COD removal device footprint, poor COD removal effect under high salt conditions, and long reaction time, and to provide a COD degradation device and use method, a catalyst, and its preparation method and application.

[0010] To achieve the above purpose, the technical solution provided by the present invention is:

[0011] A method for preparing a multifunctional adsorption catalyst is characterized in that it comprises the following steps:

[0012] 1) Preprocessing

[0013] The dried and cooled raw material 1 is ground to a particle size between 0.3 mm and 3 mm for standby use (put into a dryer for standby use, and considering the adsorption performance and use performance, the raw material 1 with a particle size between 0.3 mm and 3 mm is selected); the raw material 1 is one or a mixture of coal gangue and gasified slag; wherein the mass fraction of iron oxide in the raw material 1 is 1%-10%, the mass fraction of aluminum oxide is 10%-40%, the mass fraction of silicon dioxide is 30%-50%, the mass fraction of carbon is 3%-20%, and the remainder is doped inorganic elements such as K, P, Ba, S, etc.;

[0014] The fly ash with a dried particle size between 10 μm and 50 μm is set aside (put in a dryer for standby); wherein the mass fraction of iron oxide in the fly ash is 3%-10%, the mass fraction of aluminum oxide is 10%-30%, the mass fraction of silicon dioxide is 30%-50%, the mass fraction of unburned carbon is 1%-10%, and the remainder is doped inorganic elements such as K, P, Ba, and S; the above fly ash can be fluidized bed fly ash collected from power plants and sieved through a 500-mesh sieve;

[0015] Only by using the raw materials 1 and fly ash of the above specifications can the multifunctional adsorption catalyst required by the present invention be prepared;

[0016] 2) Activation

[0017] 2.1) The fly ash pretreated in step 1) and the raw material 1 are weighed in a mass ratio of 1:1-3:1, and water is added and stirred to form a first slurry of 10wt%-60wt%;

[0018] 2.2) adding oxalic acid to the first slurry obtained in step 2.1), followed by heating and stirring to react, and after the reaction is completed, drying the product by spray drying to obtain a first composite material;

[0019] In step 2), the product is dried by spray drying, so that the ferrous oxalate and the carrier are dispersed and fully contacted, laying a foundation for the subsequent formation of nano-scale catalytic materials;

[0020] 3) Alkali leaching

[0021] The first composite material obtained in step 2) is mixed with water to prepare a second slurry with a concentration of 10wt% to 60wt%, and an inorganic alkali solution (such as sodium hydroxide) is added to the second slurry to adjust the pH of the second slurry to 10-12, followed by heating and stirring to react, and after the reaction is completed, the product is dried by spray drying to obtain a second composite material;

[0022] Similarly, in step 3), the product is dried by spray drying, which can fully expose the iron oxide and provide sites, further laying the foundation for the subsequent formation of nano-scale catalytic materials;

[0023] 4) Sintering

[0024] The second composite material obtained in step 3) is placed in a circulating inert atmosphere and subjected to rotary sintering to obtain a multifunctional adsorption catalyst. The sintering process is specifically as follows:

[0025] The first stage: sintering temperature is 600℃-800℃, sintering time is 1h-2h, and mixed particles are obtained;

[0026] The second stage: the sintering temperature is 1100℃-1300℃, and the sintering time is 1h-2h to make the mixed particles bond.

[0027] The purpose of rotary sintering is to prevent the material from agglomerating or compacting during sintering, which would affect the product quality. The first stage of sintering in the sintering process uses raw material one and residual carbon in fly ash as reducing agents for thermal reduction reaction. The second stage of sintering uses raw material one and silicates and aluminates in fly ash as binders to prepare a composite material with a planetary structure, that is, a multifunctional adsorption catalyst containing nano-iron and multivalent states of iron oxide and ferrous oxide, which needs to be cooled and stored in a dryer for later use.

[0028] Further, in step 1), the drying temperature of raw material 1 is 80°C-120°C, the drying time is 0.5h-2h, raw material 1 is ground in a high-energy ball mill, the speed of the high-energy ball mill is 500r / min-1000r / min, and the ball milling time is 0.5h-2h;

[0029] The drying temperature of fly ash is 80℃-120℃, and the drying time is 0.5h-2h;

[0030] In step 2.2), after oxalic acid is added to the first slurry, its molar concentration is 0.1 mol / L-1 mol / L (i.e., the molar concentration of oxalic acid in the first slurry after addition); the reaction temperature is 60°C-80°C, the reaction time is 0.5h-2h, and the stirring speed is 500r / min-2000r / min; the amount of oxalic acid required is to remove calcium carbonate and generate ferrous oxalate with iron oxide, laying a foundation for subsequent reduction to elemental iron;

[0031] The product is dried by spray drying at a temperature of 150°C-300°C and a pressure of 0.1Mpa-1Mpa;

[0032] In step 3), after the inorganic alkali solution is added to the second slurry, its molar concentration is 0.1mol / L-3mol / L (i.e., the molar concentration of the inorganic alkali solution in the second slurry after addition); the reaction temperature is 60°C-80°C, the reaction time is 0.5h-2h, and the stirring speed is 500r / min-2000r / min;

[0033] The product is dried by spray drying at a temperature of 150°C-300°C and a pressure of 0.1Mpa-1Mpa;

[0034] In step 4), the second composite material obtained in step 3) is placed in a high-temperature tubular furnace and sintered in a nitrogen atmosphere with a circulation flow rate of 10L / min-30L / min, which can achieve the effect of uniform heating and dispersed sintering; wherein the rotation speed of the high-temperature tubular furnace is 50r / min-200r / min, and the heating rate is 5℃ / min-15℃ / min.

[0035] The preparation mechanism of the above multifunctional adsorbent catalyst is:

[0036] First, a large-size raw material (coal gangue and / or gasified slag) and a small-size fly ash powder are obtained by grinding and screening with a high-energy ball mill, and a fly ash + raw material mixture is prepared according to a specific mass ratio;

[0037] Second, oxalic acid is used to activate the mixture. The oxalic acid is soaked to remove calcium carbonate in the mixture, dredge the pores, and react with iron oxide to form ferrous oxalate;

[0038] Third, use alkali solution to leach silicon dioxide and aluminum oxide, dredge the pores, improve the adsorption performance of fly ash and raw material one, and expose the iron oxide contained in the mixture to provide sites for subsequent reduction modification;

[0039] Fourth, a high-temperature in-situ reduction reaction is carried out under the protection of an inert gas. First, the ferrous oxide produced by the decomposition of ferrous oxalate is reduced by using the residual carbon in the raw material 1 and the fly ash. At the same time, the iron oxide exposed on the surface of the solid particles is reduced to generate nano-iron, which is directly adsorbed on the surface of the fly ash and the raw material 1 in situ. By controlling the sintering reaction time, reaction temperature and other conditions, the amount of iron oxide and ferrous oxide reduced to nano-iron is controlled. Secondly, at a certain rotation speed and after high-temperature sintering, the raw material 1 and the fly ash adhere to each other under the action of their own silicates and aluminates to form a catalyst composite material with a planetary structure of a certain particle size.

[0040] The multifunctional adsorption catalyst prepared by the above preparation method is a carbon-based multifunctional catalytic material doped with inorganic elements, presenting a planetary structure, and comprising a carrier part and a catalytic part;

[0041] The carrier part is a spherical, flaky or irregularly shaped porous structure with a size of 1 mm to 50 mm, a pore size of 1 nm to 1000 nm, and a porosity of 10% to 80%;

[0042] The catalytic part is attached to the surface or pore size of the carrier part, and has a particle size of 1nm-100nm.

[0043] Furthermore, the catalytic part is nano-iron, iron oxide and ferrous oxide.

[0044] At the same time, the present invention also provides the use of the multifunctional adsorption catalyst prepared by the above preparation method in degrading COD of concentrated brine in mines.

[0045] Based on the application of the multifunctional adsorption catalyst, the present invention provides a COD degradation device, which is special in that it includes an advanced oxidation in-situ reaction unit, an ozone aeration dosing unit, an oxidizing agent and acid-base dosing unit, a mixing unit, a produced water recovery unit and a control unit;

[0046] The advanced oxidation in-situ reaction unit includes a plurality of reaction tanks connected in series along the water flow direction. The number of reaction tanks can be adjusted according to the specification requirements of the COD degradation device, such as 2-5, generally 3 are sufficient, which are sequentially referred to as: a primary reaction tank, a secondary reaction tank and a tertiary reaction tank along the water flow direction;

[0047] The tank body of each reaction tank is a double-layer hollow structure, the outer layer is the outer shell of the reaction tank, the inner layer is a water-permeable shell, and the cavity between the outer layer and the inner layer is filled with the multifunctional adsorption catalyst prepared by the above-mentioned preparation method; the water-permeable shell is evenly provided with a number of water-permeable holes; a water inlet pipe and a water outlet pipe are respectively provided at both ends of the tank body; wherein the water inlet pipe is coaxially arranged with the tank body, and its pipe diameter is smaller than the hole diameter of the water-permeable shell, and the water outlet pipe is arranged at the end of the tank body corresponding to the cavity between the outer layer and the inner layer, and the water inlet flow rate is greater than the water outlet flow rate, so as to ensure that the incoming water can enter the cavity through the water-permeable holes and stay there, and fully contact with the multifunctional adsorption catalyst to improve the catalytic efficiency; each reaction tank is arranged in series, the water inlet pipe of the odd-numbered reaction tank is located at the top of the tank body, and the water inlet pipe of the even-numbered reaction tank is located at the bottom of the tank body;

[0048] The ozone aeration dosing unit adds ozone to the first reaction tank (i.e., the primary reaction tank) of the advanced oxidation in-situ reaction unit; the oxidant and acid-base dosing unit adds the oxidant and acid-base to the mixing unit, and the oxidant and acid-base are fully and evenly mixed with the wastewater to be degraded entering the mixing unit before entering the advanced oxidation in-situ reaction unit;

[0049] The wastewater to be degraded enters the water production recovery unit after being degraded in the advanced oxidation in-situ reaction unit;

[0050] The control unit is a conventional control unit, which is used to control the normal operation and coordination of each unit.

[0051] Furthermore, the oxidizing agent and acid-base dosing unit includes a storage tank and a metering pump;

[0052] The mixing unit includes a pipeline mixer and a water inlet pump;

[0053] The oxidizing agent and acid and alkali in the storage tank are pumped into the pipeline mixer through the metering pump, and the wastewater to be degraded is pumped into the pipeline mixer through the inlet pump;

[0054] The ozone aeration and dosing unit comprises an ozone generator and a multiphase flow pump; the ozone generated by the ozone generator is pumped into the first reaction tank of the advanced oxidation in-situ reaction unit through the multiphase flow pump;

[0055] The produced water recovery unit comprises a produced water tank and a tail gas destruction component; the degraded waste water is collected in the produced water tank; and the unreacted ozone is processed and discharged through the tail gas destruction component.

[0056] Furthermore, the diameter of the water-permeable holes on the water-permeable shell is 0.01 mm-1 mm, and the porosity is 10%-50%;

[0057] The multiphase flow pump pumps ozone into the first reaction tank of the advanced oxidation in-situ reaction unit, and keeps its flow rate within the range of 10L / min-300L / min, so as to ensure that the multifunctional adsorption catalyst in the first reaction tank is in a suspended fluidized state and fully contacts with the wastewater to be degraded;

[0058] The oxidizing agent is hypochlorite, permanganate, perchlorate, persulfate, percarbonate or potassium ferrate, and the dosage thereof is 10 mg / L -1000 mg / L;

[0059] The alkali in the acid and alkali is sodium hydroxide, and the acid is hydrochloric acid or sulfuric acid. After pH adjustment, the pH in the reaction tank is between 3-10, preferably between 3-7;

[0060] The filling amount of the multifunctional adsorption catalyst is 30%-70% of the volume of the cavity between the outer layer and the inner layer of the tank.

[0061] Furthermore, the wastewater to be degraded has a COD of 200 mg / L-1500 mg / L, a TDS of 50 g / L-200 g / L, and a pH of 7-10;

[0062] The method for using the above-mentioned COD degradation device is special in that it comprises the following steps:

[0063] S1. The wastewater to be degraded enters the pipeline mixer through the water inlet pump, and the oxidizing agent and acid and alkali are pumped from the storage tank into the pipeline mixer through the metering pump to be fully and evenly mixed with the wastewater to be degraded, and enter the first reaction tank of the advanced oxidation in-situ reaction unit through the water inlet pipe;

[0064] S2. The wastewater to be degraded mixed with oxidizing agents and acid and alkali enters the first reaction tank through the water-permeable holes on the water-permeable shell and enters the cavity between the outer layer and the inner layer of the tank. At the same time, the ozone generated by the ozone generator is pumped into the bottom of the first reaction tank through a multiphase flow pump and enters the cavity between the outer layer and the inner layer of the tank, so that the multifunctional adsorption catalyst is in a suspended fluidized state; the wastewater to be degraded is fully contacted with the multifunctional adsorption catalyst and ozone for in-situ degradation; the wastewater treated in the first reaction tank (including the residual ozone therein) is degraded step by step in subsequent reaction tanks; the reaction time in the advanced oxidation in-situ reaction unit is 10-60 minutes;

[0065] S3. After the degradation is completed, the degradation water enters the water production tank through the outlet pipe of the last reaction tank, and the unreacted ozone is degraded by the tail gas destruction component and then discharged.

[0066] Concept and principle of the present invention:

[0067] In view of the current situation in which the COD degradation efficiency of mine brine is low, the catalyst cost is high, and the investment and floor space of the degradation device are large, the present invention combines multifunctional adsorption catalytic reaction and multi-stage advanced oxidation technology through a multi-stage "adsorption + catalytic in-situ degradation". Among them, the multifunctional adsorption catalytic reaction can efficiently adsorb COD substances, prolong the time of multifunctional advanced oxidation catalytic degradation of COD, reduce the floor space of the entire degradation device, and reduce the project investment cost; when treating the influent, an oxidizing agent is added through a pipeline mixer to fully mix the influent and the oxidizing agent, and ozone is introduced into the bottom of the reaction tank through a multiphase flow pump. The wastewater enters the cavity of the reaction tank filled with a multifunctional adsorption catalyst, and the COD in the wastewater is adsorbed by the multifunctional adsorption catalyst. The adsorbed COD is catalytically degraded in situ by the oxidizing agent and ozone, and the treated wastewater enters the subsequent multiple reaction tanks in turn to re-adsorb and degrade the undegraded small molecule COD, thereby ensuring the degradation efficiency of COD. At the same time, the multifunctional adsorption catalyst used uses coal gangue, gasification slag, and fly ash solid waste as raw materials, which reduces the cost of catalyst preparation. The entire device uses cylindrical tubular reaction tanks in series, which greatly reduces the floor space and investment of the entire reaction device.

[0068] Advantages of the present invention:

[0069] 1. The raw materials of the multifunctional adsorption catalyst prepared by the present invention are coal gangue, gasification slag and fly ash, all of which are solid wastes, and no chemical reagents and raw materials are added. It has the innovation of resource recycling, and the multifunctional adsorption catalyst prepared by the present invention has the functions of adsorption and catalytic degradation of COD; the porous adsorption and aluminate adsorption properties of coal gangue, gasification slag and fly ash are used, and the specific surface area and porosity of coal gangue, gasification slag and fly ash are improved through simple grinding and acid-base pretreatment, thereby improving the adsorption performance; the carbon and iron oxide inherent in coal gangue, gasification slag and fly ash are used to carry out in-situ redox reaction to prepare multivalent and multi-scale catalyst materials without adding catalyst raw materials and complicated preparation processes.

[0070] 2. Nano-iron, iron oxide and ferrous oxide exist on the surface and in the pores of the multifunctional adsorption catalyst prepared by the present invention, which releases ferrous ions to catalyze the in-situ oxidation agent and ozone degradation of organic matter. Coal gangue, gasification slag and fly ash serve as ferrous ion catalyst carriers and have a complexing effect at the same time, which can continuously release a certain amount of ferrous ions, maintain catalytic degradation activity, prevent a large amount of iron ions from consuming oxidants, and reduce the output of iron mud.

[0071] 3. The COD degradation device of the present invention comprises an advanced oxidation in-situ reaction unit, an ozone aeration dosing unit, an oxidant and acid-base dosing unit, a mixing unit, a water production recovery unit and a control unit; after the COD components are fully mixed with the oxidant, they enter the reaction tank and are adsorbed by a multifunctional adsorption catalyst. On the multifunctional adsorption catalyst, OH· and SO4 generated by the oxidant and ozone catalysis are .- The multifunctional adsorption catalyst has the functions of adsorption and catalytic oxidation. Nano-iron, iron ions, ozone, and oxidizing agents (such as persulfate) catalyze multifunctional catalytic reactions on the surface of the catalyst material. Nano-iron has the characteristics of high catalytic activity, many active sites and large contact area, and can efficiently and fully degrade the adsorbed COD. The adsorption and oxidation processes are carried out simultaneously. The whole process has the advantages of long COD residence time, high degradation efficiency and multi-stage oxidation. It is suitable for high-salinity wastewater and ordinary wastewater, with high treatment rate and good effect, and is suitable for promotion and use.

[0072] 4. The COD degradation device of the present invention adopts a pre-oxidation-multi-stage series deep oxidation design, and degrades COD through a pre-oxidation-multi-stage series in-situ reaction. The oxidant is fully mixed with the influent water through a pipeline mixer at the water inlet end, and ozone is only added at the bottom of the first reaction tank in the advanced oxidation in-situ reaction unit. In the subsequent reaction tanks, the unreacted ozone and oxidant can be fully utilized. A cylindrical tubular reaction tank is used. When the ozone gas is introduced, the ozone flow rate is adjusted according to the filling amount of the multifunctional adsorption catalyst, so that the entire multifunctional adsorption catalyst is in a suspended fluidized state in the tank body, so that the solid, liquid and gas three phases are fully contacted, the oxidation efficiency is improved, and the occurrence of catalyst fouling is reduced. The entire device has the characteristics of uniform water discharge, no dead angle in the oxidation reaction, sufficient oxidation reaction, compact equipment, small footprint, small catalyst loss, simple replacement of consumables, less ozone and oxidant addition, and high utilization efficiency.

[0073] 5. The present invention couples the nano-adsorption process (specifically the catalytic part of the multifunctional adsorption catalyst) with the multifunctional advanced oxidation process in situ. The multifunctional adsorption catalyst has the advantages of large specific surface area, good adsorption effect, no need for frequent regeneration, long service life and easy replacement. Adsorption, ozone catalysis and oxidant catalysis occur in situ on the surface of the catalyst material, and it has the advantages of high adsorption efficiency, long oxidation time, high oxidation efficiency and multifunctional oxidation. The multifunctional adsorption catalyst has the advantages of strong chemical corrosion resistance, multiple reaction sites, high active catalysis, no need for external energy, low cost, strong durability and good effect. The catalyst loss is small, there is no residual metal ions in the produced water, and the impact on subsequent treatment processes is small.

[0074] 6. The multifunctional adsorption catalyst prepared by the present invention uses solid waste (coal gangue, gasification slag, fly ash) as raw materials, which can not only fully realize the reuse of solid waste, but also can use the iron oxide of solid waste to generate the catalytic part in situ. In the preparation process of the multifunctional adsorption catalyst, calcium carbonate in the raw material is first removed by soaking in oxalic acid, the pores are unblocked, and the ferrous oxalate is generated by reacting with the iron oxide; then, the silicon dioxide and aluminum oxide are leached with inorganic alkali solution to unblock the pores, improve the adsorption performance of the solid waste, and at the same time, the iron oxide contained in the raw material is exposed to provide sites for subsequent reduction modification; finally, a high-temperature in-situ reduction reaction is carried out under the protection of an inert gas, and the residual carbon in the raw material is used to further reduce the ferrous oxide generated by the decomposition of ferrous oxalate and the iron oxide exposed on the surface of the raw material to generate nano-iron, which is adsorbed on the surface of the raw material in situ, and provides a catalytic function together with the unreduced iron oxide and ferrous oxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 This is a SEM image of the multifunctional adsorption catalyst prepared in Example 2;

[0076] Figure 2 The schematic diagram of the structure of the device for degrading COD of the present invention is shown in FIG.

[0077] 1-water inlet pump, 2-pipeline mixer, 3-storage tank, 4-metering pump, 5-water inlet pipe, 6-water permeable shell, 7-outer shell, 8-ozone generator, 9-multiphase flow pump, 10-water outlet pipe, 11-multifunctional adsorption catalyst, 12-tail gas destruction component, 13-water production tank;

[0078] Figure 3 This is a comparison chart of the catalytic effects of different catalyst combinations. DETAILED DESCRIPTION

[0079] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0080] 1. Multifunctional adsorption catalyst

[0081] The multifunctional adsorption catalyst includes a carrier part and a catalytic part, and the overall structure is planetary. The carrier part is a spherical, sheet-like or irregularly shaped porous structure with a size of 1mm-50mm, a pore size of 1nm-1000nm, and a porosity of 10%-80%. The catalytic part is attached to the surface or pore size of the carrier part, and the particle size is 1nm-100nm.

[0082] The preparation method of the multifunctional adsorption catalyst is to first activate the carrier part with acid to remove the impurities inside, then neutralize it with alkali, and the catalytic part (derived from coal gangue, gasification slag and fly ash) is attached to the surface and pore size of the carrier part through oxygen-free sintering. The multifunctional adsorption catalyst can activate ozone and oxidizing agents at the same time to improve the efficiency of oxidative removal of COD. Specifically, it includes the following steps:

[0083] 1) Preprocessing

[0084] Grind the dried and cooled coal gangue and / or gasified slag to a particle size of 0.3 mm-3 mm and put it into a dryer for standby use; wherein the mass fraction of iron oxide in the coal gangue and gasified slag is 1%-10%, the mass fraction of aluminum oxide is 10%-40%, the mass fraction of silicon dioxide is 30%-50%, the mass fraction of carbon is 3%-20%, and the remainder is doped inorganic elements such as K, P, Ba, S, etc.; the drying temperature is 80°C-120°C, the drying time is 0.5h-2h, and the coal gangue and / or gasified slag is placed in a high-energy ball mill for grinding, the speed of the high-energy ball mill is 500r / min-1000r / min, and the ball milling time is 0.5h-2h;

[0085] The fly ash with a drying particle size between 10 μm and 50 μm is placed in a dryer for standby use; wherein the mass fraction of iron oxide in the fly ash is 3%-10%, the mass fraction of aluminum oxide is 10%-30%, the mass fraction of silicon dioxide is 30%-50%, the mass fraction of unburned carbon is 1%-10%, and the remainder is doped inorganic elements such as K, P, Ba, and S; the drying temperature of the fly ash is 80°C-120°C, and the drying time is 0.5h-2h; the above fly ash can be fluidized bed fly ash collected from power plants;

[0086] 2) Activation

[0087] 2.1) The fly ash pretreated in step 1) and coal gangue / or gasified slag are weighed in a mass ratio of 1:1-3:1, and water is added and stirred to form a first slurry of 10wt%-60wt%;

[0088] 2.2) adding oxalic acid to the first slurry obtained in step 2.1), followed by heating and stirring to react, and spray drying the product after the reaction is completed to obtain a first composite material; wherein, after the oxalic acid is added to the first slurry, its molar concentration is 0.1 mol / L-1 mol / L; the reaction temperature is 60°C-80°C, the reaction time is 0.5h-2h, the stirring speed is 500 r / min-2000r / min; the drying temperature is 150°C-300°C, and the pressure is 0.1Mpa-1Mpa;

[0089] 3) Alkali leaching

[0090] The first composite material obtained in step 2) is mixed with water to prepare a second slurry with a concentration of 10wt%-60wt%, and a sodium hydroxide solution is added to the second slurry to adjust the pH of the second slurry to 10-12, followed by heating and stirring to react, and after the reaction is completed, the product is spray-dried to obtain a second composite material; wherein, after the second slurry is added, the molar concentration of sodium hydroxide is 0.1mol / L-3mol / L; the reaction temperature is 60℃-80℃, the reaction time is 0.5h-2h, the stirring speed is 500r / min-2000r / min; the drying temperature is 150℃-300℃, and the pressure is 0.1Mpa-1Mpa;

[0091] 4) Sintering

[0092] The second composite material obtained in step 3) is placed in a high-temperature tube furnace and sintered in a nitrogen atmosphere with a circulation flow rate of 10L / min-30L / min to obtain a multifunctional adsorption catalyst. The sintering process includes:

[0093] The first stage: the temperature is 600℃-800℃, the time is 1h-2h, and mixed particles are obtained;

[0094] The second stage: the temperature is 1100℃-1300℃, the time is 1h-2h, so that the mixed particles are bonded;

[0095] The rotation speed of the high-temperature tube furnace is 50r / min-200r / min, and the heating rate is 5℃ / min-15℃ / min; the first stage of sintering is to use coal gangue, gasification slag and residual carbon in fly ash as reducing agents for thermal reduction reaction; the second stage of sintering is to use silicates and aluminates in coal gangue, gasification slag and fly ash as binders to prepare a multifunctional adsorption catalyst with a certain particle size (the size of the carrier part is 1mm-50mm, and the particle size of the catalytic part is 1nm-100nm) with a planetary structure, wherein the pore size of the carrier part is 1nm-1000nm, and the porosity is 10%-80%; the multifunctional adsorption catalyst is a composite material containing nano-iron and multivalent states of iron oxide and ferrous oxide, which is stored in a dryer for standby use after cooling.

[0096] Example 1

[0097] 1) Preprocessing

[0098] The dried and cooled coal gangue is ground to a particle size of 0.3 mm and placed in a dryer for standby use; wherein the mass fraction of iron oxide in the coal gangue is 1%, the mass fraction of aluminum oxide is 40%, the mass fraction of silicon dioxide is 30%, the mass fraction of carbon is 20%, and the remainder is doped inorganic elements such as K, P, Ba, and S; the drying temperature is 80°C, the drying time is 0.5h, and the coal gangue is placed in a high-energy ball mill for grinding, the speed of the high-energy ball mill is 500r / min, and the ball milling time is 0.5h;

[0099] The fly ash with a particle size of 10 μm is dried and placed in a dryer for later use; wherein the mass fraction of iron oxide in the fly ash is 3%, the mass fraction of aluminum oxide is 30%, the mass fraction of silicon dioxide is 30%, the mass fraction of unburned carbon is 10%, and the remainder is doped inorganic elements such as K, P, Ba, and S; the drying temperature of the fly ash is 80°C, and the drying time is 0.5h; the above fly ash can be fluidized bed fly ash collected from power plants;

[0100] 2) Activation

[0101] 2.1) The fly ash and coal gangue pretreated in step 1) are weighed in a mass ratio of 1:1, and water is added and stirred to form a 10wt% first slurry;

[0102] 2.2) adding oxalic acid to the first slurry obtained in step 2.1), followed by heating and stirring to react, and spray drying the product after the reaction is completed to obtain a first composite material; wherein the molar concentration of oxalic acid after being added to the first slurry is 0.1 mol / L; the reaction temperature is 60°C, the reaction time is 0.5h, the stirring speed is 500r / min; the drying temperature is 150°C, and the pressure is 0.1Mpa;

[0103] 3) Alkali leaching

[0104] The first composite material obtained in step 2) is mixed with water to prepare a 10wt% second slurry, and a sodium hydroxide solution is added to the second slurry, the pH of the second slurry is adjusted to 10, and then heated and stirred to react, and after the reaction is completed, the product is spray-dried to obtain a second composite material; wherein, after the second slurry is added, the molar concentration of sodium hydroxide is 0.1 mol / L; the reaction temperature is 60°C, the reaction time is 0.5h, and the stirring speed is 500r / min; the drying temperature is 150°C, and the pressure is 0.1Mpa;

[0105] 4) Sintering

[0106] The second composite material obtained in step 3) is placed in a high-temperature tube furnace and sintered in a nitrogen atmosphere with a circulation flow rate of 10 L / min to obtain a multifunctional adsorption catalyst. The sintering process includes:

[0107] The first stage: the temperature is 600℃, the time is 1h, and the mixed particles are obtained;

[0108] The second stage: the temperature is 1100℃, the time is 1h, so that the mixed particles are bonded;

[0109] The rotation speed of the high-temperature tubular furnace is 50r / min, and the heating rate is 5℃ / min; the first stage of sintering is to use the residual carbon of coal gangue and fly ash as a reducing agent for thermal reduction reaction; the second stage of sintering is to use the silicate and aluminate in the coal gangue and fly ash as a binder to prepare a multifunctional adsorption catalyst with a certain particle size (the size of the carrier part is 1mm, and the particle size of the catalytic part is 1nm) with a planetary structure; the multifunctional adsorption catalyst is a composite material containing nano-iron and multivalent states of iron oxide and ferrous oxide, which is stored in a dryer after cooling for use.

[0110] Example 2

[0111] 1) Preprocessing

[0112] The dried and cooled coal gangue is ground to a particle size of 3 mm and placed in a dryer for standby use; the mass fraction of iron oxide in the coal gangue is 10%, the mass fraction of aluminum oxide is 10%, the mass fraction of silicon dioxide is 50%, the mass fraction of carbon is 3%, and the remainder is doped inorganic elements such as K, P, Ba, and S; the drying temperature is 120°C, the drying time is 2 hours, and the coal gangue is placed in a high-energy ball mill for grinding, the speed of the high-energy ball mill is 1000r / min, and the ball milling time is 2 hours;

[0113] The fly ash with a particle size of 50 μm is dried and placed in a dryer for later use; wherein the mass fraction of iron oxide in the fly ash is 10%, the mass fraction of aluminum oxide is 10%, the mass fraction of silicon dioxide is 50%, the mass fraction of unburned carbon is 1%, and the remainder is doped inorganic elements such as K, P, Ba, and S; the drying temperature of the fly ash is 120°C, and the drying time is 2 hours; the above fly ash can be fluidized bed fly ash collected from power plants;

[0114] 2) Activation

[0115] 2.1) The fly ash pretreated in step 1) and the raw material 1 are weighed in a mass ratio of 1:1, and water is added and stirred to form a 60wt% first slurry;

[0116] 2.2) adding oxalic acid to the first slurry obtained in step 2.1), followed by heating and stirring to react, and spray drying the product after the reaction is completed to obtain a first composite material; wherein after the addition of oxalic acid, the concentration of oxalic acid in the slurry is 1 mol / L; the reaction temperature is 80°C, the reaction time is 2h, the stirring speed is 1000r / min; the drying temperature is 300°C, and the pressure is 1Mpa;

[0117] 3) Alkali leaching

[0118] The first composite material obtained in step 2) is mixed with water to prepare a 60wt% second slurry, and a sodium hydroxide solution is added to the second slurry, the pH of the second slurry is adjusted to 12, and then heated and stirred to react, and after the reaction is completed, the product is spray-dried to obtain a second composite material; wherein, after the second slurry is added, the molar concentration of sodium hydroxide is 3 mol / L; the reaction temperature is 80°C, the reaction time is 2h, the stirring speed is 2000r / min; the drying temperature is 300°C, and the pressure is 1Mpa;

[0119] 4) Sintering

[0120] The second composite material obtained in step 3) is placed in a high-temperature tube furnace and sintered in a nitrogen atmosphere with a circulation flow rate of 30 L / min to obtain a multifunctional adsorption catalyst. The sintering process includes:

[0121] The first stage: the temperature is 800℃, the time is 2h, and the mixed particles are obtained;

[0122] The second stage: the temperature is 1300℃, the time is 2h, so that the mixed particles are bonded;

[0123] The rotation speed of the high-temperature tube furnace is 200r / min, and the heating rate is 15℃ / min; the first stage of sintering is to use the residual carbon of coal gangue and fly ash as a reducing agent for thermal reduction reaction; the second stage of sintering is to use the silicate and aluminate in the coal gangue and fly ash as a binder to prepare a multifunctional adsorption catalyst with a certain particle size (the size of the carrier part is 3mm, and the particle size of the catalytic part is 100nm) with a planetary structure; the multifunctional adsorption catalyst is a composite material containing nano-iron and multivalent states of iron oxide and ferrous oxide, which is stored in a dryer after cooling for use.

[0124] Example 3

[0125] 1) Preprocessing

[0126] The dried and cooled raw material 1 (mixture of coal gangue and gasified slag) is ground to a particle size of 2 mm and placed in a dryer for standby use; the mass fraction of iron oxide in the raw material 1 is 5%, the mass fraction of aluminum oxide is 20%, the mass fraction of silicon dioxide is 40%, the mass fraction of carbon is 8%, and the remainder is doped inorganic elements such as K, P, Ba, S, etc.; the drying temperature is 100°C, the drying time is 1.5h, and the raw material 1 is placed in a high-energy ball mill for grinding, the speed of the high-energy ball mill is 800r / min, and the ball milling time is 1.5h;

[0127] The fly ash with a dried particle size of 30 μm is placed in a dryer for standby use; wherein the mass fraction of iron oxide in the fly ash is 5%, the mass fraction of aluminum oxide is 20%, the mass fraction of silicon dioxide is 40%, the mass fraction of unburned carbon is 3%, and the remainder is doped inorganic elements such as K, P, Ba, and S; the drying temperature of the fly ash is 100°C, and the drying time is 1.5 hours; the above fly ash can be fluidized bed fly ash collected from power plants;

[0128] 2) Activation

[0129] 2.1) The fly ash pretreated in step 1) and the raw material 1 are weighed in a mass ratio of 2:1, and water is added and stirred to form a 50wt% first slurry;

[0130] 2.2) adding oxalic acid to the first slurry obtained in step 2.1), followed by heating and stirring to react, and spray drying the product after the reaction is completed to obtain a first composite material; wherein the molar concentration of oxalic acid after being added to the first slurry is 0.6 mol / L; the reaction temperature is 70°C, the reaction time is 1.5 h, the stirring speed is 1500 r / min; the drying temperature is 200°C, and the pressure is 0.6 MPa;

[0131] 3) Alkali leaching

[0132] The first composite material obtained in step 2) is mixed with water to prepare a 30wt% second slurry, and a sodium hydroxide solution is added to the second slurry, the pH of the second slurry is adjusted to 11.5, and then heated and stirred to react. After the reaction is completed, the product is spray-dried to obtain a second composite material; wherein, after the second slurry is added, the molar concentration of sodium hydroxide is 2.5 mol / L; the reaction temperature is 70°C, the reaction time is 1.5h, the stirring speed is 1000r / min; the drying temperature is 200°C, and the pressure is 0.6Mpa;

[0133] 4) Sintering

[0134] The second composite material obtained in step 3) is placed in a high-temperature tube furnace and sintered in a nitrogen atmosphere with a circulation flow rate of 20 L / min to obtain a multifunctional adsorption catalyst. The sintering process includes:

[0135] The first stage: the temperature is 700℃, the time is 1.5h, and the mixed particles are obtained;

[0136] The second stage: the temperature is 1200℃, the time is 1.5h, so that the mixed particles are bonded;

[0137] The rotation speed of the high-temperature tube furnace is 150r / min, and the heating rate is 10℃ / min; the first stage sintering is to use raw material one and residual carbon in fly ash as reducing agents for thermal reduction reaction; the second stage sintering is to use raw material one and silicate and aluminate in fly ash as binders to prepare a multifunctional adsorption catalyst with a certain particle size (the size of the carrier part is 2.6mm, and the particle size of the catalytic part is 10nm) with a planetary structure; the multifunctional adsorption catalyst is a composite material containing nano-iron and multivalent states of iron oxide and ferrous oxide, which is stored in a dryer after cooling for use.

[0138] Figure 1This is a SEM photo of the multifunctional adsorption catalyst prepared in Example 2. It can be seen from the figure that the multifunctional adsorption catalyst mainly includes a carrier part and a catalytic part. The carrier part is spherical with a particle size of millimeters, and the nano-scale catalytic part is well supported on the surface and in the pores of the carrier part. Table 1 is the XRF characterization analysis of the gangue-fly ash carrier material used in Example 2 (without sintering in step 4) and the obtained multifunctional adsorption catalyst. It can be seen from the table that compared with the gangue-fly ash carrier material, the multifunctional adsorption catalyst prepared by the above method of the present invention has a greatly increased content of the catalytic element Fe. The main reason is that after acid-base treatment and reduction, the iron element contained in the mixture is exposed to form iron oxide, ferrous oxide and nano-iron, which increases the proportion of iron elements and thus increases the catalyst active sites.

[0139] Table 1 XRF analysis of multifunctional adsorption catalyst materials

[0140]

[0141] 2. Device for efficiently degrading COD in concentrated brine in mines

[0142] like Figure 2 As shown, the device includes an advanced oxidation in-situ reaction unit, an ozone aeration dosing unit, an oxidant and acid-base dosing unit, a mixing unit, a water production recovery unit and a control unit.

[0143] In this embodiment, the advanced oxidation in-situ reaction unit includes three reaction tanks connected in series along the water flow direction, namely, a primary reaction tank, a secondary reaction tank, and a tertiary reaction tank. The tank body of each reaction tank is a cylinder with a double-layer hollow structure; the outer layer has a diameter of 100mm-1000mm and a thickness of 1mm-100mm, which is the outer shell of the reaction tank; the inner layer has a diameter of 50mm- 500mm, thickness 1mm-10mm, for the water-permeable shell; the cavity between the outer layer and the inner layer is filled with the multifunctional adsorption catalyst developed by the present invention, and the filling amount is 30%-70% of the volume of the cavity between the outer layer and the inner layer of the tank; a number of water-permeable holes are evenly arranged on the water-permeable shell, the aperture of the water-permeable hole is 0.01mm-1mm, and the porosity is 10%-50%; both ends of the reaction tank body are closed, and a water inlet pipe and a water outlet pipe are coaxially arranged respectively, wherein the water inlet pipe is coaxially arranged with the tank body, and its pipe diameter is smaller than the aperture of the water-permeable shell, and the water outlet pipe is arranged at the end of the tank body corresponding to the cavity between the outer layer and the inner layer, and when in use, the water inlet flow rate is greater than the water outlet flow rate, ensuring that the incoming water can enter the cavity through the water-permeable holes and stay, and fully contact with the multifunctional adsorption catalyst to improve the catalytic efficiency; the reaction tank is made of 2205 duplex stainless steel as a whole, and of course, polymer materials can also be used. The three reaction tanks are arranged in series, the water outlet pipe of the primary reaction tank is connected with the water inlet pipe of the secondary reaction tank, the water outlet pipe of the secondary reaction tank is connected with the water inlet pipe of the tertiary reaction tank, and the water inlet pipes of the primary reaction tank and the tertiary reaction tank are located at the top of the tank body, and the water inlet tank of the secondary reaction tank is located at the bottom of the tank body. In this way, even the COD that is not degraded in the primary reaction tank can be fully degraded in the secondary reaction tank.

[0144] The oxidant and acid-base dosing unit includes a storage tank, a metering pump, and related valves and pipes. The storage tank (can also be a box) is used to store a certain amount of oxidant and acid-base. It is made of plastic materials such as PP, PVC, PE, etc. and has a volume of 1m 3 -5m 3 The metering pump adopts a diaphragm metering pump, made of UPVC, with a flow rate of 10L / h-200L / h. The dosage is adjusted according to the inlet water quality and COD content, and the oxidant and acid and alkali are added through the relevant valve pipeline. The oxidant is hypochlorite, permanganate, perchlorate, persulfate, percarbonate or potassium ferrate, and the dosage is 10mg / L-1000mg / L. The alkali in the acid and alkali is sodium hydroxide, and the acid is hydrochloric acid or sulfuric acid. After pH adjustment, the pH in the reaction tank is between 3-10, preferably between 3-7.

[0145] The mixing unit includes a pipeline mixer and an inlet pump. The pipeline mixer is a three-way pipeline mixer, which allows the inlet water to be evenly mixed with the oxidant and the acid and alkali. It is made of carbon steel, lined with rubber inside, and has a diameter of 50 mm-500 mm. The incoming water is passed into the pipeline mixer through the inlet pump, where it is fully and homogeneously mixed with the oxidant and the acid and alkali. It then enters the primary reaction tank through the inlet pipe, and the water flows through the permeable holes of the inner permeable shell into the cavity between the outer layer and the inner layer. The COD components in the water are adsorbed by the multifunctional adsorption catalyst and catalytically oxidized and degraded. The produced water enters the secondary reaction tank and the tertiary reaction tank in turn, and enters the produced water recovery unit after further oxidation.

[0146] The ozone aeration dosing unit includes an ozone generator, a multiphase flow pump and a gas-liquid stabilization tank. Ozone is generated by the ozone generator, and then passed into the bottom of the primary reaction tank through the multiphase flow pump, and enters the reaction tank to participate in the oxidation reaction. Among them, the ozone generator produces 10kg / h-50kg / h of ozone, and the concentration is 100mg / L-210mg / L; the multiphase flow pump is made of duplex steel, and the flow rate is 10L / min-300L / min. The multifunctional adsorption catalyst in the reaction tank can be in a suspended fluidized state by adjusting the ozone flow rate;

[0147] The produced water recovery unit includes a produced water tank and a tail gas destruction component. The produced water treated by the above-mentioned advanced oxidation in-situ reaction unit enters the produced water tank, and the unreacted ozone contained in the produced water is degraded and discharged through the tail gas destruction component. The volume of the produced water tank is 1m 3 -100m 3 The water tank is made of PP, PVC, PE or FRP; the exhaust gas destruction components include demister, demister, destruction tower, catalyst, induced draft fan, etc., which are existing equipment.

[0148] The control unit is used to control the normal operation and coordination of each unit.

[0149] The method for using the above-mentioned device for efficiently degrading COD of concentrated brine in mines comprises the following steps:

[0150] S1. The wastewater to be degraded enters the pipeline mixer through the water inlet pump, and the oxidizing agent and acid and alkali are pumped from the storage tank into the pipeline mixer through the metering pump to be fully and homogeneously mixed with the wastewater to be degraded, and enter the reaction tank through the water inlet pipe of the primary reaction tank of the advanced oxidation in-situ reaction unit;

[0151] S2. After the wastewater to be degraded mixed with oxidizing agents and acid and alkali enters the primary reaction tank, it enters the cavity between the outer layer and the inner layer of the tank through the permeable holes on the permeable shell. At the same time, the ozone generated by the ozone generator is pumped into the bottom of the primary reaction tank through a multiphase flow pump and enters the cavity between the outer layer and the inner layer of the tank, so that the multifunctional adsorption catalyst is in a suspended fluidized state; the wastewater to be degraded is fully contacted with the multifunctional adsorption catalyst and ozone for in-situ degradation (in this process, the COD component in the wastewater is adsorbed by the multifunctional adsorption catalyst, and the adsorbed COD component is catalyzed by the oxidizing agent and the hydroxyl free radical OH· and sulfate free radical SO4 ·- The wastewater treated in the primary reaction tank is further degraded in the secondary and tertiary reaction tanks (the unremoved COD is further adsorbed by the multifunctional adsorption catalyst in the secondary and tertiary reaction tanks, and the unreacted oxidant and ozone degrade the COD components); the whole reaction time is 10min-60min;

[0152] S3. After the degradation is completed, the degradation water enters the water production tank through the outlet pipe of the tertiary reaction tank. The unreacted ozone is degraded by the tail gas destruction component and then discharged, which will not damage the atmospheric environment.

[0153] Example 4

[0154] 100L of secondary reverse osmosis brine with TDS of 52618mg / L and COD of 456mg / L was pumped into pipeline mixer 2 through inlet pump 1, and 5mmol / L Na2S2O8 solution was added into pipeline mixer 2 through metering pump 4 at a dosage of 50L / h. In pipeline mixer 2, Na2S2O8 solution was fully mixed with influent, and the mixed solution entered into primary reaction tank through inlet pipe 5. COD component in influent was adsorbed by multifunctional adsorption catalyst, and influent was adsorbed by permeable water. The water-permeable hole of the shell 6 enters the cavity between the outer layer and the inner layer, 148 mg / L of ozone is generated by the ozone generator 8, and then passed into the bottom of the primary reaction tank through the multiphase flow pump 9 and enters the reaction tank to participate in the oxidation reaction. The adsorbed COD components are catalytically oxidized by ozone and oxidizing agents, and then enter the subsequent reaction tank through the outlet pipe 10 of the primary reaction tank. After the three-stage reaction (a total of 10 minutes), the produced water enters the water tank 13, and the remaining tail gas is treated by the tail gas destruction component 12 and then discharged. According to the test, the COD in the produced water is 113 mg / L, and the COD removal rate is 75.2%.

[0155] Example 5

[0156] 100L of secondary reverse osmosis brine with TDS of 53176mg / L and COD of 528mg / L of mine water is pumped into the pipeline mixer 2 through the water inlet pump 1, and 6mmol / L NaClO4 solution is added into the pipeline mixer 2 through the metering pump 4 at a dosage of 80L / h. In the pipeline mixer 2, the NaClO4 solution is fully mixed with the influent, and the mixed solution enters the primary reaction tank through the water inlet pipe 5. The COD component in the influent is adsorbed by the multifunctional adsorption catalyst, and the influent enters the cavity between the outer layer and the inner layer through the water permeable holes of the permeable shell 6. 130mg / L of ozone is generated by the ozone generator 8, and then passed into the bottom of the primary reaction tank through the multiphase flow pump 9 and enters the reaction tank to participate in the oxidation reaction. After catalytic oxidation by ozone and oxidizing agent, it enters the subsequent reaction tank through the outlet pipe 10 of the primary reaction tank. The produced water after the tertiary reaction (30min in total) enters the produced water tank 13, and the remaining tail gas is treated by the tail gas destruction component 12 and then discharged. Through testing, the COD in the produced water was 127.5 mg / L and the removal rate was 75.9%.

[0157] Example 6

[0158] 100L The secondary reverse osmosis concentrated brine of mine water with TDS of 61689 mg / L and COD of 696 mg / L is pumped into the pipeline mixer 2 through the water inlet pump 1, and 10 mmol / L KMnO4 solution is added into the pipeline mixer 2 through the metering pump 4 at a dosage of 52 L / h. In the pipeline mixer 2, the KMnO4 solution is fully mixed with the influent, and the mixed solution enters the primary reaction tank through the water inlet pipe 5. The COD component in the influent is adsorbed by the multifunctional adsorption catalyst, and the influent enters the cavity between the outer layer and the inner layer through the water permeable holes of the permeable shell 6. 151 mg / L of ozone is generated by the ozone generator 8, and then passed into the bottom of the primary reaction tank through the multiphase flow pump 9 and enters the reaction tank to participate in the oxidation reaction. After catalytic oxidation by ozone and oxidizing agent, it enters the subsequent reaction tank through the outlet pipe 10 of the primary reaction tank. The produced water after the tertiary reaction (60 minutes in total) enters the produced water tank 13, and the remaining tail gas is treated by the tail gas destruction component 12 and then discharged. Through testing, the COD in the produced water was 139.2 mg / L and the removal rate was 80%.

[0159] Example 7

[0160] 100L of secondary reverse osmosis brine with TDS of 52618 mg / L and COD of 820 mg / L was pumped into the pipeline mixer 2 through the inlet pump 1, and 7 mmol / L Na2S2O8 solution was added into the pipeline mixer 2 through the metering pump 4 at a dosage of 50L / h. In the pipeline mixer 2, the Na2S2O8 solution was fully mixed with the inlet water, and the mixed solution entered the primary reaction tank through the inlet pipe 5. The COD component in the inlet water was adsorbed by the multifunctional adsorption catalyst, and the inlet water entered the cavity between the outer layer and the inner layer through the permeable holes of the permeable shell 6. 150 mg / L of ozone is generated by the ozone generator 8, and then passed into the bottom of the primary reaction tank through the multiphase flow pump 9 and enters the reaction tank to participate in the oxidation reaction. The adsorbed COD components are catalytically oxidized by ozone and oxidizing agents, and then enter the subsequent reaction tank through the primary reaction tank outlet pipe 10. The final effluent re-enters the front-end water inlet circulation treatment. The produced water after 60 minutes of reaction enters the produced water tank 13, and the remaining tail gas is treated by the tail gas destruction component 12 and then discharged. The produced water after 60 minutes passed the test, and the COD in the produced water was 185mg / L, with a removal rate of 77.4%.

[0161] In order to verify the degradation effect of the present invention, the present invention and the existing process are also compared:

[0162] Comparative Example 1: The degradation was carried out using an ozone oxidation process, and the other conditions were the same as those in Example 6.

[0163] Comparative Example 2: Degradation was carried out using a persulfate oxidation process, and other conditions were the same as those in Example 6.

[0164] Comparative Example 3: Degradation was carried out using ozone + persulfate oxidation process, and other conditions were the same as those in Example 6.

[0165] The results are as follows Figure 3 As shown in the figure, it can be seen that after 60 minutes of reaction (in actual engineering and experiments, the reaction control time is about 60 minutes), the overall COD degradation tends to be stable. Compared with comparative examples 1-3, the COD degradation efficiency of Example 6 of the present invention can be as high as 80%.

[0166] In summary, the multifunctional adsorption catalyst, the device and the method for degrading COD of the present invention can efficiently remove COD in a short time and have a good application prospect.

[0167] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.

Claims

1. A method for preparing a multifunctional adsorption catalyst, characterized in that: The following steps are involved: 1) Preprocessing The dried and cooled raw material 1 is ground to a particle size between 0.3 mm and 3 mm for standby use; the raw material 1 is one or a mixture of coal gangue and gasified slag; wherein the mass fraction of iron oxide in the raw material 1 is 1%-10%, the mass fraction of aluminum oxide is 10%-40%, the mass fraction of silicon dioxide is 30%-50%, and the mass fraction of carbon is 3%-20%; Dry fly ash with a particle size between 10 μm and 50 μm for standby use; wherein the mass fraction of iron oxide in the fly ash is 3%-10%, the mass fraction of aluminum oxide is 10%-30%, the mass fraction of silicon dioxide is 30%-50%, and the mass fraction of unburned carbon is 1%-10%; 2) Activation 2.1) The fly ash pretreated in step 1) and the raw material 1 are weighed in a mass ratio of 1:1-3:1, and water is added and stirred to form a first slurry of 10wt%-60wt%; 2.2) adding oxalic acid to the first slurry obtained in step 2.1), followed by heating and stirring to react, and after the reaction is completed, drying the product by spray drying to obtain a first composite material; 3) Alkali leaching The first composite material obtained in step 2) is mixed with water to prepare a second slurry with a concentration of 10wt% to 60wt%, and an inorganic alkali solution is added to the second slurry to adjust the pH value of the second slurry to 10-12, followed by heating and stirring to react, and after the reaction is completed, the product is dried by spray drying to obtain a second composite material; 4) Sintering The second composite material obtained in step 3) is placed in a circulating inert atmosphere and subjected to rotary sintering to obtain a multifunctional adsorption catalyst. The sintering process is specifically as follows: The first stage: sintering temperature is 600℃-800℃, sintering time is 1h-2h; The second stage: the sintering temperature is 1100℃-1300℃, and the sintering time is 1h-2h.

2. The method for preparing the multifunctional adsorption catalyst according to claim 1, characterized in that: In step 1), the drying temperature of raw material 1 is 80°C-120°C, the drying time is 0.5h-2h, and raw material 1 is ground in a high-energy ball mill, the speed of the high-energy ball mill is 500r / min-1000r / min, and the ball milling time is 0.5h-2h; The drying temperature of fly ash is 80℃-120℃, and the drying time is 0.5h-2h; In step 2.2), after oxalic acid is added to the first slurry, its molar concentration is 0.1mol / L-1mol / L; the reaction temperature is 60℃-80℃, the reaction time is 0.5h-2h, and the stirring speed is 500r / min-2000r / min; the product is dried by spray drying at a temperature of 150℃-300℃ and a pressure of 0.1Mpa-1Mpa; In step 3), after the inorganic alkali solution is added to the second slurry, its molar concentration is 0.1mol / L-3mol / L; the reaction temperature is 60°C-80°C, the reaction time is 0.5h-2h, and the stirring speed is 500r / min-2000r / min; the product is dried by spray drying at a temperature of 150°C-300°C and a pressure of 0.1Mpa-1Mpa; In step 4), the second composite material obtained in step 3) is placed in a high-temperature tube furnace and sintered in a nitrogen atmosphere with a circulation flow rate of 10L / min-30L / min; wherein the rotation speed of the high-temperature tube furnace is 50r / min-200r / min, and the heating rate is 5℃ / min-15℃ / min.

3. A multifunctional adsorption catalyst, characterized in that: Prepared by the preparation method according to any one of claims 1-2, comprising a carrier part and a catalytic part; The carrier part is a porous structure with a pore size of 1nm-1000nm; The catalytic part is attached to the surface or pores of the carrier part, and has a particle size of 1nm-100nm.

4. The multifunctional adsorption catalyst according to claim 3, characterized in that: The catalytic part is nano iron, iron oxide and ferrous oxide.

5. Use of the multifunctional adsorption catalyst prepared by the preparation method according to any one of claims 1-2 in degrading COD in concentrated brine in mines.

6. A device for degrading COD, characterized in that: It includes an advanced oxidation in-situ reaction unit, an ozone aeration dosing unit, an oxidant and acid-base dosing unit, a mixing unit, a produced water recovery unit and a control unit; The advanced oxidation in-situ reaction unit includes a plurality of reaction tanks connected in series along the water flow direction; The tank body of each reaction tank is a double-layer hollow structure, the outer layer is the outer shell of the reaction tank, the inner layer is a water-permeable shell, and the cavity between the outer layer and the inner layer is filled with the multifunctional adsorption catalyst prepared by the preparation method described in any one of claims 1-2; a plurality of water-permeable holes are evenly arranged on the water-permeable shell; and a water inlet pipe and a water outlet pipe are respectively arranged at both ends of the tank body; The ozone aeration dosing unit adds ozone to the first reaction tank of the advanced oxidation in-situ reaction unit; the oxidant and acid-base dosing unit adds the oxidant and acid-base to the mixing unit, and the oxidant and acid-base are fully and evenly mixed with the wastewater to be degraded entering the mixing unit before entering the advanced oxidation in-situ reaction unit; The wastewater to be degraded enters the water production recovery unit after being degraded in the advanced oxidation in-situ reaction unit.

7. The device for degrading COD according to claim 6, characterized in that: The oxidizing agent and acid-base dosing unit comprises a storage tank and a metering pump; The mixing unit includes a pipeline mixer and a water inlet pump; The oxidizing agent and acid and alkali in the storage tank are pumped into the pipeline mixer through the metering pump, and the wastewater to be degraded is pumped into the pipeline mixer through the water inlet pump; The ozone aeration and dosing unit comprises an ozone generator and a multiphase flow pump; the ozone generated by the ozone generator is pumped into the first reaction tank of the advanced oxidation in-situ reaction unit through the multiphase flow pump; The produced water recovery unit comprises a produced water tank and a tail gas destruction component; the degraded waste water is collected in the produced water tank; and the unreacted ozone is processed and discharged through the tail gas destruction component.

8. The device for degrading COD according to claim 7, characterized in that: The diameter of the water permeable holes on the water permeable shell is 0.01mm-1mm, and the porosity is 10%-50%; The multiphase flow pump pumps ozone into the first reaction tank of the advanced oxidation in-situ reaction unit, and keeps its flow rate within the range of 10L / min-300L / min; The oxidizing agent is hypochlorite, permanganate, perchlorate, persulfate, percarbonate or potassium ferrate, and the dosage thereof is 10 mg / L-1000 mg / L; The alkali in the acid and alkali is sodium hydroxide, and the acid is hydrochloric acid or sulfuric acid. After pH adjustment, the pH in the reaction tank is between 3 and 10; The filling amount of the multifunctional adsorption catalyst is 30%-70% of the volume of the cavity between the outer layer and the inner layer of the tank.

9. The device for degrading COD according to claim 8, characterized in that: The COD of the wastewater to be degraded is 200mg / L-1500mg / L, TDS is 50g / L-200g / L, and pH is 7-10.

10. The method for using the COD degradation device according to claim 9, characterized in that: The following steps are involved: S1. The wastewater to be degraded enters the pipeline mixer through the water inlet pump, and the oxidizing agent and acid and alkali are pumped from the storage tank into the pipeline mixer through the metering pump to be fully and evenly mixed with the wastewater to be degraded, and enter the first reaction tank of the advanced oxidation in-situ reaction unit through the water inlet pipe; S2. The wastewater to be degraded mixed with oxidizing agents and acid and alkali enters the first reaction tank through the water-permeable holes on the water-permeable shell and enters the cavity between the outer layer and the inner layer of the tank. At the same time, the ozone generated by the ozone generator is pumped into the bottom of the first reaction tank through a multiphase flow pump and enters the cavity between the outer layer and the inner layer of the tank, so that the multifunctional adsorption catalyst is in a suspended fluidized state; the wastewater to be degraded is fully contacted with the multifunctional adsorption catalyst and ozone, and is degraded in situ; the wastewater treated in the first reaction tank is degraded step by step in subsequent reaction tanks; S3. After the degradation is completed, the degradation water enters the water production tank through the outlet pipe of the last reaction tank, and the unreacted ozone is degraded by the tail gas destruction component and then discharged.

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