Metal-based water purifying agent for sewage treatment and preparation method thereof

Abstract

The application discloses a metal-based water purifying agent for sewage treatment and a preparation method thereof, and belongs to the technical field of water purifying agent processing, and is used for solving the technical problem that the settling performance and stability of the water purifying agent in the prior art need to be further improved, and specifically comprises the following steps: stirring a mixed solution and modified sludge-based carbon in a reaction kettle, heating to 45-55 DEG C, and standing for 2-4 hours to obtain the metal-based water purifying agent; the application is characterized in that: the broken sludge block and the activated bamboo chips treated by microwaves are modified by a zinc chloride solution to obtain pretreated sludge, the pretreated sludge powder is modified by calcium carbonate, and further combined with nano-Fe3O4 particles to prepare modified sludge-based carbon; the modified sludge-based carbon is combined with coal gasification fine slag regenerated metal-based gel to form the metal-based water purifying agent, so that the settling performance of the metal-based water purifying agent in sewage treatment is improved, and the stability of the metal-based water purifying agent is also improved.

Description

Technical Field

[0001] This invention relates to the field of water purification agent processing technology, specifically to a metal-based water purification agent for wastewater treatment and its preparation method. Background Technology

[0002] With the acceleration of industrialization and urbanization, wastewater commonly contains pollutants that are difficult to degrade, such as heavy metal ions, organic dyes, and phosphorus fluorides. Traditional treatment methods are unable to meet the requirements of high efficiency, low consumption, and resource utilization.

[0003] Metal-based water purification agents have attracted widespread attention in the field of wastewater treatment due to their strong flocculation, high adsorption, and adjustable structural stability. Currently, the most commonly used metal-based water purification agents mainly include inorganic polymeric flocculants based on polyvalent metal ions such as aluminum, iron, and manganese, such as polyaluminum chloride, polyferric sulfate, and their composite derivatives. To improve their adsorption performance and selectivity, researchers generally use materials such as carbon, silicon, and clay for loading modification, or introduce functional groups such as carboxyl, amino, and sulfonic acid groups, as well as nanotechnology, to achieve effective complexation, sedimentation, and separation between metal ions and pollutants.

[0004] In existing technologies, on the one hand, traditional aluminum-iron flocculants are prone to hydrolysis and instability under fluctuating acid and alkali conditions, and have limited efficiency in treating low concentrations of organic pollutants. On the other hand, modification methods often rely on physical doping or single functional group modification, resulting in weak interfacial bonding between metal colloids and matrix materials, making them easy to separate and be lost in water, and difficult to achieve high selective adsorption in complex water bodies. In addition, the adsorbent material structure lacks multi-scale pores and directional functional group layout, resulting in low utilization of adsorption sites, and non-magnetic or weakly magnetic water purification agents are difficult to effectively recover, limiting their industrial recycling. Summary of the Invention

[0005] The purpose of this invention is to provide a metal-based water purification agent for wastewater treatment and its preparation method, in order to solve the technical problem that the sedimentation performance and stability of existing water purification agents need to be further improved.

[0006] The objective of this invention can be achieved through the following technical solution: a method for preparing a metal-based water purification agent for wastewater treatment, comprising the following steps:

[0007] S1. Place the coal gasification fine slag and hydrochloric acid aqueous solution in a reactor and stir. Heat the reactor to 70-80℃ and keep it at the temperature for 1-2 hours. Then, process the solution to obtain the filtrate.

[0008] The reaction principle for preparing the filtrate is as follows:

[0009] During the reaction, Al2O3, Fe3O4 and Fe2O3 contained in the coal gasification fine slag are converted into trivalent aluminum ions, divalent iron ions and trivalent iron ions under the action of hydrochloric acid aqueous solution. They dissolve in hydrochloric acid aqueous solution, and insoluble impurities are removed by filtration to obtain a filtrate containing trivalent aluminum ions, divalent iron ions and trivalent iron ions.

[0010] S2. Place the filtrate, potassium permanganate, and polyacrylamide in a reaction vessel, and add sodium hydroxide aqueous solution to adjust the pH to 2.5 ± 0.3 to obtain a mixed solution;

[0011] The reaction principle for preparing the mixture is as follows:

[0012] During the reaction, ferrous ions in the filtrate are oxidized to ferric ions by potassium permanganate. The polyacrylamide molecular chain contains polar groups such as -CONH and -NH, exhibiting excellent complexing and coordination abilities, and can react with Fe... 3+ Al 3+ Metal ions form complexes through electron pairs. Adjusting the pH of the filtrate system with sodium hydroxide aqueous solution can promote polymerization while avoiding the formation of Fe(OH)3 precipitate, resulting in a mixed solution.

[0013] S3. Place the mixture and modified sludge-based carbon in a reactor and stir. Heat to 45-55℃ and let stand for 2-4 hours to obtain a metal-based water purification agent.

[0014] The preparation reaction principle of metal-based water purification agents is as follows:

[0015] During the reaction, the surface of the modified sludge-based char is rich in functional groups such as carboxyl, hydroxyl, and amino groups, which can interact with Fe through electrostatic adsorption, hydrogen bonding, and coordination bonds. 3+ Al 3+ Complexes combine to form interfacial complex structures such as Fe-OC and Al-OC. After standing at 45-55℃ for 2-4 hours, the metal colloids can be further polymerized into long-chain structures. The metal colloids slowly deposit and cross-link on the carbon surface to form a stable structure, ultimately obtaining a stable, uniform, and composite water purification agent material.

[0016] Further, in step S1, the ratio of the coal gasification fine slag to the hydrochloric acid aqueous solution is 5-10g:80-100mL, and the concentration of the hydrochloric acid aqueous solution is 1-3mol / L. The post-treatment step includes: after the reaction is completed, the reaction system is cooled to room temperature and filtered to obtain the filtrate; in step S2, the ratio of the filtrate, potassium permanganate, and polyacrylamide is 40-60mL:0.1-0.2g:0.2-0.4g, and the concentration of the sodium hydroxide aqueous solution is 2-10wt%; in step S3, the ratio of the mixed solution to the modified sludge-based carbon is 60-80mL:2-4g.

[0017] Furthermore, the modified sludge-based char is prepared by the following steps:

[0018] A1. Place the pretreated sludge powder, calcium carbonate and deionized water in a reactor and stir. Heat the reactor to 75-85℃ and keep it at that temperature for 6-8 hours. After post-treatment, the modified sludge-based carbon crude product is obtained.

[0019] A2. After uniformly mixing the modified sludge-based carbon crude product and nano-iron oxide particles, calcination is carried out to obtain modified sludge-based carbon.

[0020] The reaction principle for preparing modified sludge-based char is as follows:

[0021] During the reaction, the organic matter in the sludge undergoes thermal dehydration, carbon-hydrogen bond breaking, and aromatization during the heating process of 550-950℃, forming a carbon skeleton and generating layered or porous carbon materials in situ. At high temperature, nano-iron oxide particles are partially embedded in the surface or pores of the carbon skeleton to form a stable composite structure, thus obtaining modified sludge-based carbon.

[0022] Further, in step A1, the ratio of the pretreated sludge powder, calcium carbonate, and deionized water is 4-6g:4-6g:50-70mL. The post-treatment step includes: after the reaction is completed, the reaction system is cooled to room temperature, and the product is transferred to an oven at 100-110℃ and dried for 20-24h to obtain modified sludge-based carbon crude product; in step A2, the weight ratio of the modified sludge-based carbon crude product and nano-iron oxide particles is 4-6:0.5-1.

[0023] Further, in step A2, the preparation method of the modified sludge-based carbon is as follows: the crude modified sludge-based carbon and nano-ferric oxide particles are mixed evenly and then added to a tube furnace. The temperature is increased to 550-650℃ at a rate of 5℃ / min, and the reaction is maintained for 0.5-1h. Then, the temperature is increased to 850-950℃ at a rate of 10℃ / min, and the reaction is maintained for 0.5-1h. After the product cools to room temperature, it is washed 2-4 times with deionized water, transferred to an oven at a temperature of 70-80℃, dried to constant weight, and passed through a 300-mesh sieve to obtain the modified sludge-based carbon.

[0024] Furthermore, the pretreated sludge is prepared by the following steps:

[0025] B1. Crush the sludge blocks and sieve them to obtain sludge powder;

[0026] B2. Microwave activation treatment is applied to bamboo shavings to obtain activated bamboo shavings;

[0027] The reaction principle for preparing activated bamboo chips is as follows:

[0028] During the reaction, microwave heating at 400-600W rapidly vaporizes the moisture and volatiles in the bamboo chips, triggering an internal micro-explosion effect. This quickly depolymerizes the cellulose, hemicellulose, and lignin structures in the bamboo chips, forming primary pyrolysis channels. This induces a porous structure and increases its specific surface area in a short time. Activated bamboo chips, acting as a pore-directing agent for biochar and a carbonaceous auxiliary framework, can improve the quality of subsequent composite carbon structures, ultimately yielding activated bamboo chips.

[0029] B3. Place the sludge powder, activated bamboo chips and zinc chloride solution in a reaction vessel and stir. Let it stand at room temperature for 20-24 hours. The resulting pretreated sludge is then obtained through post-treatment.

[0030] The reaction principle for preparing pretreated sludge is as follows:

[0031] During the reaction, zinc chloride acts as a classic chemical activator, which can dehydrate organic matter and promote the rearrangement of the carbon skeleton structure. During room temperature impregnation, zinc ions complex with the hydroxyl and carboxyl groups of organic matter in sludge powder and activated bamboo chips, breaking the colloidal and humic network in the sludge and providing a pre-activation path for subsequent pyrolysis. In the subsequent carbonization process, zinc chloride plays a triple role as a template, dehydrator and expansion agent, which can promote the formation of microporous structure in modified sludge-based carbon, and finally obtain pretreated sludge.

[0032] Furthermore, in step B3, the ratio of the sludge powder, activated bamboo chips, and zinc chloride solution is 5-7g:1-3g:10-15mL, and the concentration of the zinc chloride solution is 30-40wt%. The post-treatment step includes: after the reaction is completed, the mixture is filtered, and the filter cake is transferred to an oven at a temperature of 50-60℃ and dried to constant weight to obtain pretreated sludge.

[0033] Furthermore, the method for preparing the activated bamboo chips is as follows: bamboo chips are added to a microwave generator with a power set to 400-600W and processed for 3-5 minutes to obtain activated bamboo chips.

[0034] The present invention also provides a metal-based water purifier for wastewater treatment, which is prepared by the above-described method for preparing a metal-based water purifier for wastewater treatment.

[0035] The present invention has the following beneficial effects:

[0036] 1. This invention modifies crushed sludge blocks and microwave-treated activated bamboo chips with zinc chloride solution to obtain pretreated sludge. This pretreated sludge has a loose structure, abundant functional groups, and obvious pores, exhibiting excellent adsorption performance and loading capacity. Treatment with calcium carbonate under medium-temperature hydrothermal conditions promotes a synergistic effect between calcium carbonate and the organic matter and inorganic minerals in the pretreated sludge. During subsequent calcination or heat treatment, some calcium carbonate decomposes to generate CO2 gas, forming numerous micropores and mesopores, thereby significantly increasing the specific surface area and pore volume of the sludge-based carbon. This rich hierarchical porous structure provides ample adsorption sites for subsequent loading of metal ions or oxide particles. Finally, through composite calcination with nano-ferric oxide particles, a modified sludge with good magnetic responsiveness is formed. Mud-based charcoal provides an ideal three-dimensional support carrier for metal-based water purifiers, enhancing the fixation efficiency of polymerized iron and aluminum ions and preventing their hydrolysis and precipitation loss. Simultaneously, the abundant carboxyl and hydroxyl groups on the charcoal surface generate complexes and bridging interfaces with metal ions, promoting the formation of stable structures such as Fe-OC and Fe-O-Si, thus improving the colloidal stability and structural integrity of the purifier. Furthermore, its highly developed porous structure provides rapid channels for pollutant adsorption, interfacial reactions, and reaction product diffusion. Synergistically working with the polymerization system in the mixed liquid, it forms a three-in-one composite purification mechanism of flocculation, adsorption, and oxidation, improving the flocculation and sedimentation rate, turbidity reduction rate, and magnetic recovery capability of metal-based water purifiers in treating complex phosphorus-containing wastewater.

[0037] 2. This invention utilizes activated bamboo chips prepared through microwave treatment. The surface of these chips develops numerous pores and active functional groups such as hydroxyl and carboxyl groups. In subsequent steps, these activated bamboo chips can interact with sludge powder and zinc chloride solution to form a composite carbon-based precursor. The addition of activated bamboo chips improves the pore structure of the sludge carbon, creating a porous composite network with organic matter and cellulose as its framework. This increases the ratio of micropores to mesopores, significantly enhancing the specific surface area and adsorption capacity. Furthermore, the volatile organic compounds released during the carbonization process help form interconnected channels, resulting in a more developed internal pore structure, which is beneficial for the uniform loading of Fe3O4 particles and metal complexes. In addition, the introduction of activated bamboo chips can regulate the chemical properties of the carbon surface; its oxygen-containing functional groups can complex or hydrogen bond with metal ions, improving the carbon's ability to adsorb Fe. 3+ Mn 4 + The ability to fix metal components prevents the aggregation and loss of metal particles during preparation and use, further improving the turbidity reduction rate and stability of metal-based water purifiers, and further reducing their settling time.

[0038] 3. This invention modifies pretreated sludge micro-powder with calcium carbonate and further combines it with nano-iron oxide particles to prepare modified sludge-based carbon. The porous structure of the modified sludge-based carbon provides a large number of adsorption sites for metal-based adsorbents, effectively immobilizing polynuclear hydroxyl metal complexes in the mixed liquid and preventing their aggregation or precipitation deactivation, thereby improving the dispersion stability and reactivity of metal-based water purification agents. Furthermore, the polar functional groups such as carboxyl and hydroxyl groups on the surface of the modified sludge-based carbon can interact with Fe... 3+ Mn 4+ When metal ions form chemical complexes or bridging bonds, a stable metal-carbon interface structure is generated, which improves the settling performance of metal-based water purifiers. In addition, modified sludge-based carbon can also adsorb various organic matter and heavy metal ions in sewage through physical adsorption, pore capture, and π-π stacking, achieving synergistic effects of flocculation and adsorption. This composite structure of inorganic metal colloids and porous carbon carriers not only improves the turbidity reduction rate but also enhances the removal effect on recalcitrant organic pollutants. The introduced nano-iron oxide particles endow the modified sludge-based carbon with good magnetic response characteristics, enabling the water purifier to be quickly separated and reused through an external magnetic field during the recycling process after water treatment, reducing operating costs and improving the sustainability of materials. Detailed Implementation

[0039] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The coal gasification slag used in this invention has an average particle size of 23.9 μm, a ferric oxide content of 8.6%, and an alumina content of 14%.

[0041] The polyacrylamide used in this invention has a pH value of 10-14, complies with national standards, and its main component is acrylamide.

[0042] The nano-ferric oxide particles used in this invention have a purity greater than 99.2% and a specific surface area of ​​10-30 m². 2 / g, with a particle size of 200nm;

[0043] The bamboo shavings used in this invention have an average particle size of 80-100 mesh.

[0044] The sludge blocks used in this invention have an effective sludge particle size greater than 70%, and are also known as anaerobic granular sludge.

[0045] Example 1

[0046] This embodiment provides a method for preparing pretreated sludge for use in metal-based water purification agents for wastewater treatment, comprising the following steps:

[0047] Step I: Preparation of sludge micro powder

[0048] Sludge blocks are added to a crusher for crushing and then passed through a 60-mesh sieve to obtain sludge powder.

[0049] Step II: Preparation of activated bamboo shavings

[0050] Add bamboo shavings to a microwave generator with a power of 400W and process for 3 minutes to obtain activated bamboo shavings.

[0051] Step III: Preparation of pretreated sludge

[0052] Weigh out 50g of sludge powder, 10g of activated bamboo chips and 100mL of 30wt% zinc chloride solution and place them in a reaction vessel. Stir and let stand at room temperature for 20h. After the reaction is complete, filter the mixture and transfer the filter cake to an oven at 50℃. Dry the cake to constant weight to obtain pretreated sludge.

[0053] Example 2

[0054] This embodiment provides a method for preparing pretreated sludge for use in metal-based water purification agents for wastewater treatment, comprising the following steps:

[0055] Step I: Preparation of sludge micro powder

[0056] Sludge blocks are added to a crusher for crushing and then passed through a 60-mesh sieve to obtain sludge powder.

[0057] Step II: Preparation of activated bamboo shavings

[0058] Add bamboo shavings to a microwave generator with a power of 500W and process for 4 minutes to obtain activated bamboo shavings.

[0059] Step III: Preparation of pretreated sludge

[0060] Weigh out 60g of sludge powder, 20g of activated bamboo chips and 125mL of 35wt% zinc chloride solution and place them in a reaction vessel. Stir and let stand at room temperature for 22h. After the reaction is complete, filter the mixture and transfer the filter cake to an oven at 55℃. Dry the cake to constant weight to obtain pretreated sludge.

[0061] Example 3

[0062] This embodiment provides a method for preparing pretreated sludge for use in metal-based water purification agents for wastewater treatment, comprising the following steps:

[0063] Step I: Preparation of sludge micro powder

[0064] Sludge blocks are added to a crusher for crushing and then passed through a 60-mesh sieve to obtain sludge powder.

[0065] Step II: Preparation of activated bamboo shavings

[0066] Add bamboo shavings to a microwave generator with a power of 600W and process for 5 minutes to obtain activated bamboo shavings.

[0067] Step III: Preparation of pretreated sludge

[0068] Weigh out 70g of sludge powder, 30g of activated bamboo chips and 150mL of 40wt% zinc chloride solution and place them in a reaction vessel. Stir and let stand at room temperature for 24h. After the reaction is complete, filter the mixture and transfer the filter cake to an oven at 60℃. Dry the cake to constant weight to obtain pretreated sludge.

[0069] Example 4

[0070] This embodiment provides a method for preparing modified sludge-based carbon for use in metal-based water purification agents for wastewater treatment, comprising the following steps:

[0071] Step ①: Preparation of modified sludge-based charcoal crude product

[0072] Weigh 40g of the pretreated sludge powder prepared in Example 1, 40g of calcium carbonate and 500mL of deionized water and place them in a reaction vessel and stir. Heat the reaction vessel to 75°C and keep it at that temperature for 6 hours. After the reaction is complete, wait for the reaction system to cool to room temperature and transfer the product to an oven at 100°C and dry it for 20 hours to obtain the modified sludge-based carbon crude product.

[0073] Step 2: Preparation of modified sludge-based carbon

[0074] Weigh out 40g of modified sludge-based char crude product and 5g of nano-ferric oxide particles, mix them evenly, and add them to a tube furnace. Heat the furnace to 550℃ at a rate of 5℃ / min and keep it at that temperature for 0.5h. Then heat the furnace to 850℃ at a rate of 10℃ / min and keep it at that temperature for 0.5h. After the product cools to room temperature, wash it twice with deionized water, transfer it to an oven at 70℃, dry it to constant weight, and pass it through a 300-mesh sieve to obtain modified sludge-based char.

[0075] Example 5

[0076] This embodiment provides a method for preparing modified sludge-based carbon for use in metal-based water purification agents for wastewater treatment, comprising the following steps:

[0077] Step ①: Preparation of modified sludge-based charcoal crude product

[0078] Weigh 50g of the pretreated sludge powder prepared in Example 2, 50g of calcium carbonate and 600mL of deionized water and place them in a reaction vessel and stir. Heat the reaction vessel to 80°C and keep it at that temperature for 7 hours. After the reaction is complete, wait for the reaction system to cool to room temperature and transfer the product to an oven at 105°C and dry it for 22 hours to obtain the modified sludge-based carbon crude product.

[0079] Step 2: Preparation of modified sludge-based carbon

[0080] Weigh out 50g of modified sludge-based char crude product and 7g of nano-ferric oxide particles, mix them evenly, and add them to a tube furnace. Heat the furnace to 600℃ at a rate of 5℃ / min and keep it at that temperature for 1 hour. Then heat the furnace to 900℃ at a rate of 10℃ / min and keep it at that temperature for 1 hour. After the product cools to room temperature, wash it three times with deionized water, transfer it to an oven at 75℃, dry it to constant weight, and pass it through a 300-mesh sieve to obtain modified sludge-based char.

[0081] Example 6

[0082] This embodiment provides a method for preparing modified sludge-based carbon for use in metal-based water purification agents for wastewater treatment, comprising the following steps:

[0083] Step ①: Preparation of modified sludge-based charcoal crude product

[0084] Weigh 60g of the pretreated sludge powder prepared in Example 3, 60g of calcium carbonate and 700mL of deionized water and place them in a reaction vessel and stir. Heat the reaction vessel to 85°C and keep it at that temperature for 8 hours. After the reaction is complete, wait for the reaction system to cool to room temperature and transfer the product to an oven at 110°C and dry it for 24 hours to obtain the modified sludge-based carbon crude product.

[0085] Step 2: Preparation of modified sludge-based carbon

[0086] Weigh out 60g of modified sludge-based char crude product and 10g of nano-ferric oxide particles, mix them evenly, and add them to a tube furnace. Heat the furnace to 650℃ at a rate of 5℃ / min and keep it at that temperature for 1 hour. Then heat the furnace to 950℃ at a rate of 10℃ / min and keep it at that temperature for 1 hour. After the product cools to room temperature, wash it four times with deionized water, transfer it to an oven at 80℃, dry it to constant weight, and pass it through a 300-mesh sieve to obtain modified sludge-based char.

[0087] Example 7

[0088] This embodiment provides a method for preparing a metal-based water purification agent for wastewater treatment, comprising the following steps:

[0089] Step 1: Prepare filtrate

[0090] Weigh 50g of coal gasification fine slag and 800mL of 1mol / L hydrochloric acid aqueous solution and place them in a reaction vessel and stir. Heat the reaction vessel to 70℃ and keep it at that temperature for 1h. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, and obtain the filtrate.

[0091] Step 2: Preparation of the mixture

[0092] Weigh out 400 mL of filtrate, 1 g of potassium permanganate and 2 g of polyacrylamide and place them in a reaction vessel. Add 2 wt% sodium hydroxide aqueous solution to adjust the pH to 2.5 to obtain a mixed solution.

[0093] Step 3: Preparation of metal-based water purification agent

[0094] Weigh 600 mL of the mixture and 20 g of the modified sludge-based carbon prepared in Example 4 and place them in a reaction vessel. Stir, heat to 45 °C, and let stand for 2 h to obtain a metal-based water purification agent.

[0095] Example 8

[0096] This embodiment provides a method for preparing a metal-based water purification agent for wastewater treatment, comprising the following steps:

[0097] Step 1: Prepare filtrate

[0098] Weigh out 75g of coal gasification fine slag and 900mL of 2mol / L hydrochloric acid aqueous solution and place them in a reaction vessel. Stir the mixture and heat the reaction vessel to 75℃. Keep the temperature for 1.5h. After the reaction is complete, wait for the reaction system to cool to room temperature and filter to obtain the filtrate.

[0099] Step 2: Preparation of the mixture

[0100] Weigh out 500 mL of filtrate, 1.5 g of potassium permanganate and 3 g of polyacrylamide and place them in a reaction vessel. Add 5 wt% sodium hydroxide aqueous solution to adjust the pH to 2.6 to obtain a mixed solution.

[0101] Step 3: Preparation of metal-based water purification agent

[0102] Weigh 700 mL of the mixture and 30 g of the modified sludge-based carbon prepared in Example 4 into a reaction vessel and stir. Heat to 50 °C and let stand for 3 h to obtain a metal-based water purification agent.

[0103] Example 9

[0104] This embodiment provides a method for preparing a metal-based water purification agent for wastewater treatment, comprising the following steps:

[0105] Step 1: Prepare filtrate

[0106] Weigh 100g of coal gasification fine slag and 1000mL of 3mol / L hydrochloric acid aqueous solution and place them in a reaction vessel and stir. Heat the reaction vessel to 80℃ and keep it at that temperature for 2 hours. After the reaction is complete, wait for the reaction system to cool to room temperature, filter it, and obtain the filtrate.

[0107] Step 2: Preparation of the mixture

[0108] Weigh out 600 mL of filtrate, 2 g of potassium permanganate and 4 g of polyacrylamide and place them in a reaction vessel. Add 10 wt% sodium hydroxide aqueous solution to adjust the pH to 2.8 to obtain a mixed solution.

[0109] Step 3: Preparation of metal-based water purification agent

[0110] Weigh 800 mL of the mixture and 40 g of the modified sludge-based carbon prepared in Example 4, place them in a reaction vessel and stir. Heat to 55 °C and let stand for 4 h to obtain a metal-based water purification agent.

[0111] Comparative Example 1

[0112] The difference between this comparative example and Example 9 is that the addition of activated bamboo chips is omitted in step III when preparing the pretreated sludge.

[0113] Comparative Example 2

[0114] The difference between this comparative example and Example 9 is that calcium carbonate was omitted in step ① when preparing the modified sludge-based carbon crude product.

[0115] Comparative Example 3

[0116] The difference between this comparative example and Example 9 is that, in step ② when preparing modified sludge-based carbon, the addition of nano-iron oxide particles is omitted.

[0117] Performance testing:

[0118] 100 mL of 0.1 g / mL kaolin aqueous solution was selected to simulate sewage suspension, and 6 g of the metal-based water purification agent prepared in Examples 7-9 and Comparative Examples 1-3 was added. The turbidity reduction rate and sedimentation time reduction rate of the metal-based water purification agent prepared in Examples 7-9 and Comparative Examples 1-3 were tested in accordance with the standard T / CECS 10356-2024 "Flocculants for Wastewater Treatment of Washed Sand and Gravel Aggregates".

[0119] The stability of the metal-based water purification agents prepared in Examples 7-9 and Comparative Examples 1-3 was evaluated in accordance with the standard YS / T 802-2012 "Flocculants for Alumina Production".

[0120] 100 mL of simulated phosphorus-containing wastewater with a phosphorus content of 10 mg / L was selected, and 0.05 g of the metal-based water purification agent prepared in Examples 7-9 and Comparative Examples 1-3 was added for adsorption testing. The total phosphorus content of the simulated phosphorus-containing wastewater purified by the metal-based water purification agent prepared in Examples 7-9 and Comparative Examples 1-3 was calculated with reference to the standard GB 18918-2002 "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants".

[0121] Metal-based water purification agents were added to phosphorus-containing wastewater samples for purification. After stirring and reaction, the recovered metal-based water purification agents were adsorbed and weighed. The magnetic recovery rate was calculated using the formula: In the formula: m0 is the weight of the metal-based water purification agent before water purification, and m1 is the weight of the metal-based water purification agent magnetically recovered after water purification. Specific data are shown in Table 1.

[0122] Table 1 - Performance Test Data for Each Sample

[0123] Project Group Example 7 Example 8 Example 9 Comparative Example 1 Comparative Example 2 Comparative Example 3 Turbidity reduction rate / % 98 99 98 79 74 85 Settling time reduction rate / % 84 87 85 68 63 71 Stability / month 12 13 13 8 7 9 <![CDATA[Total phosphorus content / mg·L -1 > 0.3 0.2 0.2 0.7 0.8 0.4 Magnetic recovery rate / % 88 89 87 73 76 23

[0124] Data Analysis:

[0125] Comparative analysis of the data in Table 1 reveals that, compared to the purification process without the use of the metal-based water purifier prepared in this invention, the turbidity reduction rate is 99%, the sedimentation time reduction rate is 84%, it can be stably stored for 13 months, the magnetic recovery rate is 89%, and the total phosphorus content of the purified wastewater is 0.2 mg·L⁻¹. -1 The data in this invention are all superior to those in the comparative example. This invention modifies the crushed sludge blocks and microwave-treated activated bamboo chips with zinc chloride solution to obtain pretreated sludge. The pretreated sludge powder is then modified with calcium carbonate and further combined with nano-iron oxide particles to prepare modified sludge-based carbon. The modified sludge-based carbon is then combined with metal-based gel regenerated from coal gasification fine slag to generate a metal-based water purification agent. This not only improves the settling performance of the metal-based water purification agent in wastewater treatment but also enhances its stability.

[0126] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a metal-based water purification agent for wastewater treatment, characterized in that, Includes the following steps: S1. Place the coal gasification fine slag and hydrochloric acid aqueous solution in a reactor and stir. Heat the reactor to 70-80℃ and keep it at the temperature for 1-2 hours. Then, process the solution to obtain the filtrate. S2. Place the filtrate, potassium permanganate, and polyacrylamide in a reaction vessel, and add sodium hydroxide aqueous solution to adjust the pH to 2.5 ± 0.3 to obtain a mixed solution; S3. Place the mixture and modified sludge-based carbon in a reactor and stir. Heat to 45-55℃ and let stand for 2-4 hours to obtain a metal-based water purification agent. The modified sludge-based char is prepared by the following steps: A1. Place the pretreated sludge powder, calcium carbonate and deionized water in a reactor and stir. Heat the reactor to 75-85℃ and keep it at that temperature for 6-8 hours. After post-treatment, the modified sludge-based carbon crude product is obtained. A2. After uniformly mixing the modified sludge-based carbon crude product and nano-iron oxide particles, calcination is carried out to obtain modified sludge-based carbon. The pretreated sludge is prepared by the following steps: B1. Crush the sludge blocks and sieve them to obtain sludge powder; B2. Microwave-activated bamboo shavings are then obtained. B3. Place the sludge powder, activated bamboo chips and zinc chloride solution in a reaction vessel and stir. Let it stand at room temperature for 20-24 hours. The post-treatment yields the pretreated sludge. The method for preparing activated bamboo chips is as follows: bamboo chips are added to a microwave generator with a power set to 400-600W and processed for 3-5 minutes to obtain activated bamboo chips.

2. The method for preparing a metal-based water purification agent for wastewater treatment according to claim 1, characterized in that, In step S1, the ratio of the coal gasification fine slag to the hydrochloric acid aqueous solution is 5-10g:80-100mL, and the concentration of the hydrochloric acid aqueous solution is 1-3mol / L; in step S2, the ratio of the filtrate, potassium permanganate, and polyacrylamide is 40-60mL:0.1-0.2g:0.2-0.4g, and the concentration of the sodium hydroxide aqueous solution is 2-10wt%; in step S3, the ratio of the mixed solution to the modified sludge-based carbon is 60-80mL:2-4g.

3. The method for preparing a metal-based water purification agent for wastewater treatment according to claim 1, characterized in that, In step A1, the ratio of the amount of pretreated sludge powder, calcium carbonate, and deionized water is 4-6g:4-6g:50-70mL; in step A2, the weight ratio of the modified sludge-based carbon crude product and nano-iron oxide particles is 4-6:0.5-1.

4. The method for preparing a metal-based water purification agent for wastewater treatment according to claim 1, characterized in that, In step A2, the modified sludge-based carbon is prepared by mixing the crude modified sludge-based carbon and nano-ferric oxide particles evenly and then adding them to a tube furnace. The temperature is increased to 550-650℃ at a rate of 5℃ / min and kept at this temperature for 0.5-1h. Then, the temperature is increased to 850-950℃ at a rate of 10℃ / min and kept at this temperature for 0.5-1h. After the product cools to room temperature, it is washed 2-4 times with deionized water, transferred to an oven at 70-80℃, dried to constant weight, and passed through a 300-mesh sieve to obtain the modified sludge-based carbon.

5. The method for preparing a metal-based water purification agent for wastewater treatment according to claim 1, characterized in that, In step B3, the ratio of the amount of sludge powder, activated bamboo chips and zinc chloride solution is 5-7g:1-3g:10-15mL, and the concentration of the zinc chloride solution is 30-40wt%.

6. A metal-based water purification agent for wastewater treatment, characterized in that, The metal-based water purifier for wastewater treatment is prepared using a method described in any one of claims 1-5.