Porous ceramsite adsorption material prepared from straw biochar and rare earth tailings as well as preparation method and application of porous ceramsite adsorption material

Abstract

The invention provides a porous ceramsite adsorption material prepared from straw biochar and rare earth tailings as well as a preparation method and application of the porous ceramsite adsorption material, and belongs to the technical field of environmental functional adsorption materials. The preparation method of the porous ceramsite adsorption material using the straw biochar and the rare earth tailings comprises the following steps: sequentially performing acid pickling and drying on the straw biochar to obtain acidified biomass charcoal; the rare earth tailings are subjected to ball milling, and tailings fine powder is obtained; mixing the acidified biomass charcoal, the tailing fine powder, the attapulgite and the wood chips to obtain a mixture; adding a binding agent and water into the mixture, and sequentially performing kneading and extrusion molding to obtain a ceramsite precursor; and calcining the ceramsite precursor in a protective atmosphere to obtain the porous ceramsite adsorption material. The technical problems that a traditional adsorption material is low in adsorption capacity, poor in strength and difficult to recycle are solved through ternary compounding of the acidified biomass charcoal, the rare earth tailings and the attapulgite and in combination with wood chip pore-forming, segmented calcination and acid pickling pretreatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental functional adsorption materials, and particularly relates to a porous ceramsite adsorption material using straw biochar and rare earth tailings and a preparation method and application thereof. BACKGROUND

[0002] With the rapid development of industry, the problem of combined pollution of heavy metal ions (such as Pb 2+ , Cd 2+ , Cr 6+ ) and organic pollutants (such as phenol, methyl orange, methylene blue) in water bodies is increasingly prominent, which seriously threatens the ecological environment and human health. At present, the adsorption method has become one of the mainstream technologies for water pollution treatment due to its simple operation and high efficiency, but the existing adsorption materials still have significant limitations: 1) High raw material cost and strong resource dependence: Traditional adsorption materials (such as activated carbon, zeolite) depend on natural mineral resources (such as high-quality clay, shale), or need complex preparation process (such as high-temperature activation of activated carbon), which not only consumes non-renewable resources, but also has high production cost, making it difficult to be widely applied; 2) Disconnection between solid waste treatment and pollution control: The annual output of agricultural waste straw is huge, and most of them are treated by incineration, which easily causes air pollution; the rare earth tailings produced by rare earth smelting are long-term stacked due to their complex composition and low utilization rate, which occupies land resources, and the heavy metals and harmful components contained in the tailings also penetrate and pollute the soil and groundwater, so the disposal of these two kinds of solid wastes has become an environmental problem; 3) Conflict between adsorption performance and structural stability: Although some new adsorption materials improve the adsorption capacity through porous structure, they have the problem of low strength due to the existence of pores, such as the poor mechanical strength of pure biomass carbon adsorbent, which is easy to be broken and lost in water; traditional ceramsite has high strength, but its pore structure is single and the adsorption sites are insufficient, so the treatment effect on combined pollutants is not good; 4) Insufficient environmental protection in the process: Some adsorption materials use toxic and harmful modifiers in the preparation process, or the raw materials are oxidized without protective atmosphere during calcination (such as the loss of biomass carbon), which not only reduces the performance of the product, but also may cause secondary pollution, which does not meet the green and environmental protection requirements of the industry.

[0003] Therefore, it is of great significance to provide a porous ceramsite adsorption material which can realize high-value utilization of solid waste, low-cost preparation, high-performance adsorption and structural stability. SUMMARY

[0004] In order to solve the above technical problems, the purpose of the present application is to provide a porous ceramsite adsorption material using straw biochar and rare earth tailings and a preparation method and application thereof.

[0005] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions: The application provides a preparation method of porous ceramsite adsorption material using straw biochar and rare earth tailings, and comprises the following steps: 1) sequentially performing acid washing and drying on the straw biochar to obtain acidified biomass charcoal; 2) performing ball milling on the rare earth tailings to obtain tailing fine powder; 3) mixing the acidified biomass charcoal, the tailing fine powder, attapulgite and wood chips to obtain a mixture; 4) adding a binding agent and water to the mixture, and sequentially performing kneading and extrusion molding to obtain a ceramsite precursor; 5) calcining the ceramsite precursor in a protective atmosphere to obtain the porous ceramsite adsorption material.

[0006] Further, in the step 1), the acid washing reagent is a hydrochloric acid or sulfuric acid solution, and the molar concentration of the hydrochloric acid or sulfuric acid solution is 1-5 mol / L; The acid washing is performed under stirring, the stirring speed is 100-300 r / min, and the acid washing time is 2-6 h.

[0007] Further, in the step 1), the mass-volume ratio of the straw biochar and the acid washing reagent is 1 g:5-10 mL; The drying temperature is 100-120 DEG C, and the drying time is 4-8 h.

[0008] Further, in the step 2), the ball-to-material ratio of the ball milling is 8-12:1, the ball milling speed is 200-350 r / min, and the ball milling time is 1-3 h; The particle size of the tailing fine powder is ≤100 μm.

[0009] Further, in the step 3), the mass ratio of the acidified biomass charcoal, the tailing fine powder, the attapulgite and the wood chips is 5-20:30-60:10-30:5-15; The mixing is performed under stirring, the mixing speed is 200-400 r / min, and the mixing time is 10-30 min.

[0010] Further, in the step 4), the mass ratio of the mixture, the binding agent and water is 100:3-10:20-40; The binding agent is one or more of cement, sodium silicate, bentonite, starch and sodium carboxymethyl cellulose.

[0011] Further, in the step 4), the kneading temperature is 20-30 DEG C, and the kneading time is 15-40 min; In the extrusion process, the rotation speed of the screw is 30-60 r / min, the temperature is 25-50 DEG C, and the feeding speed is 10-20 kg / h. The ceramic particle precursor has a particle size of 3-10 mm.

[0012] Further, in the step 5), the protective atmosphere is nitrogen or argon. The calcination process comprises the following steps: firstly, increasing the temperature to 200-300 DEG C at a rate of 2-5 DEG C / min, and keeping the temperature for 1-2 h; and then increasing the temperature to 700-900 DEG C at a rate of 5-10 DEG C / min, and calcining for 2-5 h.

[0013] The application further provides a porous ceramic particle adsorption material prepared by the preparation method.

[0014] The application further provides application of the porous ceramic particle adsorption material in adsorption of heavy metal ions and / or organic pollutants in a water body, wherein the heavy metal ions include one or more of lead ions, cadmium ions and chromium ions, and the organic pollutants include one or more of phenol, methyl orange and methylene blue.

[0015] The application has the following beneficial effects: 1) The application realizes high-value utilization of solid waste, effectively reduces cost and pollution, and realizes collaborative utilization of two typical solid wastes by optimizing raw material combination and process design: after acid modification, the straw is converted into a high-activity adsorption carrier to avoid environmental pollution caused by incineration; the rare earth tailings are finely ground by ball milling, and the SiO2, Al2O3 and rare earth oxides (such as La2O3 and CeO2) contained therein not only serve as adsorption active sites, but also participate in the construction of the ceramic skeleton, effectively solving the problem of tailing accumulation pollution. 2) The application builds a multi-stage adsorption system by using multiple raw materials, and the acidified biomass charcoal provides natural microporous structure and active sites such as carboxyl and hydroxyl groups to preferentially adsorb organic pollutants; the metal oxides in the rare earth tailings powder strengthen the adsorption of heavy metals through ion exchange and complexation; the interlayer channels of the attapulgite supplement the adsorption capacity for small molecule pollutants; the through-type mesoporous structure formed by the calcination of wood chips accelerates the diffusion of pollutants, and the final product has a saturation adsorption capacity for heavy metal ions far exceeding that of traditional ceramic particles, and can simultaneously treat composite contaminated water bodies; 3) The application uses a combination of a binding agent and a segmented calcination process to form a glass phase-crystal phase composite skeleton, significantly improving the compressive strength and porosity of the ceramic particles, effectively solving the contradiction between porosity and strength, and meeting the loading and impact resistance requirements in actual water treatment. 4) The method of the present application does not use toxic and harmful reagents, and adopts a protective atmosphere to avoid oxidation loss of biomass charcoal, and the calcination product of sawdust and organic binder is only CO2 and H2O, without secondary pollution; and the process parameters are controllable, realizing large-scale production; 5) The porous ceramic adsorbent material prepared by the present application can be directly applied to industrial wastewater, domestic sewage, and contaminated surface water in different scenarios, and shows high adsorption capacity for Pb 2+ , Cd 2+ , Cr 6+ and other heavy metal ions, and phenol, methyl orange, methylene blue and other organic pollutants, and can be recycled through acid washing and heat regeneration, further reducing the treatment cost, and having significant economic and environmental benefits. DETAILED DESCRIPTION

[0016] The present application provides a preparation method of porous ceramic adsorbent material using straw biochar and rare earth tailings, comprising the following steps: 1) sequentially acid washing and drying the straw biochar to obtain acidified biomass charcoal; 2) ball milling the rare earth tailings to obtain tailing fine powder; 3) mixing the acidified biomass charcoal, tailing fine powder, attapulgite and sawdust to obtain a mixture; 4) adding a binder and water to the mixture, and sequentially kneading and extruding to obtain a ceramic granule precursor; 5) calcining the ceramic granule precursor under a protective atmosphere to obtain a porous ceramic adsorbent material.

[0017] In the present application, in step 1), the acid washing reagent used is hydrochloric acid or sulfuric acid solution, and the molar concentration of the hydrochloric acid or sulfuric acid solution is 1-5 mol / L, preferably 2-4 mol / L, and further preferably 3 mol / L; The acid washing is carried out under stirring, and the stirring speed is 100-300 r / min, preferably 150-250 r / min, and further preferably 200 r / min; the acid washing time is 2-6 h, preferably 3-5 h, and further preferably 4 h.

[0018] In the present application, the straw biochar (prepared by straw pyrolysis) surface is easy to attach ash (such as CaCO3, MgO and other inorganic impurities) and residual organic matter, which can block the natural pores of the carbon and cover the surface active groups (such as carboxyl-COOH, hydroxyl-OH), thereby directly reducing its adsorption capacity. In the pickling process, by using strong acid to react with metal oxides / carbonates in the ash, the pore blockage is effectively removed, the porous structure of the biochar is restored and expanded, and the pore size distribution is more uniform. In addition, the acid solution in the pickling process also etches the carbon surface, increases the number of micropores and mesopores, and introduces more negatively charged active groups, providing more binding sites for the subsequent adsorption of positively charged heavy metal ions in water.

[0019] In the present application, in step 1), the mass-volume ratio of straw biochar and pickling reagent is 1g:5~10mL, preferably 1g:6~9mL, and further preferably 1g:7~8mL; The drying temperature is 100~120℃, preferably 105~115℃, and further preferably 110℃; the drying time is 4~8h, preferably 5~7h, and further preferably 6h.

[0020] In the present application, drying can effectively remove free moisture, prevent residual moisture from rapidly evaporating during calcination, and thus avoid the cracking phenomenon of ceramsite. In addition, this process does not damage the already formed porous structure, ensuring that the acidified biomass charcoal remains in a dry powder state, thereby facilitating subsequent mixing with other raw materials in precise mass proportions, effectively ensuring the stability and consistency of the formula.

[0021] In the present application, in step 2), the ball-to-material ratio of ball milling is 8~12:1, preferably 9~11:1, and further preferably 10:1; the rotation speed of ball milling is 200~350r / min, preferably 230~320r / min, and further preferably 250~300r / min; the ball milling time is 1~3h, preferably 1.5~2.5h, and further preferably 2h; The particle size of the tailings fine powder is ≤100μm, preferably ≤95μm, and further preferably ≤90μm.

[0022] In the present application, the specific surface area of the tailings fine powder increases significantly, exposing more metal oxide active sites that can effectively adsorb heavy metal ions through ion exchange and complexation; in addition, the hydroxyl group can also adsorb organic pollutants. At the same time, fine powder particles are more easily mixed with acidified biomass charcoal, attapulgite and other raw materials, thereby avoiding stress concentration points during the molding process and reducing the risk of ceramsite cracking during subsequent calcination.

[0023] In the present application, in the step 3), the mass ratio of the acidified biomass charcoal, tailing fine powder, palygorskite and sawdust is 5-20:30-60:10-30:5-15, preferably 7-18:35-55:15-25:8-12, and further preferably 10-15:40-50:20:10.

[0024] In the present application, the acidified biomass charcoal provides a natural porous structure, and meanwhile the active groups on its surface and the metal oxides of the tailing fine powder form adsorption site complementation, improving the treatment capacity for composite pollutants; the tailing fine powder is used for auxiliary adsorption, on the one hand, the metal oxides are used to strengthen adsorption; on the other hand, in the subsequent calcination, the clay minerals of the palygorskite and the tailing fine powder have a sintering reaction to form the inorganic framework of the ceramsite, ensuring the mechanical strength of the product; the palygorskite is a layered clay mineral, which has excellent cohesiveness and ion exchange capacity, and the interlayer channel can be used as a secondary adsorption site to adsorb small-molecule organic pollutants or trace heavy metal ions, and meanwhile, the layered structure will retain part of the pores after calcination, supplementing the porosity of the ceramsite; the sawdust is a natural organic material as a green pore-forming agent and pore-controlling agent, which is uniformly dispersed in the material during the mixing stage, and will be completely decomposed during the subsequent calcination to form through-type pores.

[0025] In the present application, the mixing is carried out under stirring, the rotating speed of the mixing is 200-400 r / min, preferably 250-350 r / min, and further preferably 300 r / min; the mixing time is 10-30 min, preferably 15-25 min, and further preferably 20 min.

[0026] In the present application, the stirring at 200-400 r / min can ensure that the four raw materials are uniformly dispersed at the micro level, avoiding excessive pore formation caused by local aggregation of the sawdust, and uneven adsorption performance caused by insufficient tailing in local areas, thereby ensuring the performance consistency of each ceramsite.

[0027] In the present application, in the step 4), the mass ratio of the mixed material, the binding agent and water is 100:3-10:20-40, preferably 100:4-9:25-35, and further preferably 100:5-8:30. The binding agent is one or more of cement, sodium silicate, bentonite, starch and sodium carboxymethyl cellulose, preferably one or more of cement, sodium silicate, bentonite and sodium carboxymethyl cellulose, and further preferably one or more of cement, sodium silicate and sodium carboxymethyl cellulose.

[0028] In this invention, the binder is used to fill the gaps between raw material particles, fixing the material particles through physical and chemical bonding, thereby preventing breakage during extrusion. In addition, the inorganic binder reacts with tailings and attapulgite during subsequent calcination, further enhancing the strength of the ceramsite.

[0029] In this invention, in step 4), the kneading temperature is 20~30℃, preferably 22~28℃, and more preferably 24~26℃; the kneading time is 15~40min, preferably 20~35min, and more preferably 25~30min. During the extrusion molding process, the screw rotation speed is 30~60 r / min, preferably 35~55 r / min, more preferably 40~50 r / min; the temperature is 25~50℃, preferably 30~45℃, more preferably 35~40℃; and the feeding speed is 10~20 kg / h, preferably 12~18 kg / h, more preferably 14~16 kg / h. The particle size of the ceramsite precursor is 3~10mm, preferably 4~9mm, and more preferably 5~8mm.

[0030] In this invention, in step 5), the protective atmosphere is nitrogen or argon, preferably argon.

[0031] In this invention, a protective atmosphere is used to prevent the biochar from being oxidized, thereby avoiding the collapse of its porous structure and loss of adsorption performance; at the same time, the rare earth oxides in the tailings are prevented from being oxidized, so as not to affect its complexation and reduction adsorption capacity for pollutants, and to ensure the stable adsorption activity of the final product.

[0032] In this invention, the calcination process is as follows: first, the temperature is raised to 200-300°C at a rate of 2-5°C / min, and held for 1-2 hours; then, the temperature is raised to 700-900°C at a rate of 5-10°C / min, and calcined for 2-5 hours.

[0033] Preferably, the temperature is first raised to 220-280℃ at a rate of 2.5-4.5℃ / min and held for 1.2-1.8h, then raised to 750-850℃ at a rate of 6-9℃ / min and calcined for 2.5-4.5h.

[0034] A further preferred method involves first heating to 240-260°C at a rate of 3-4°C / min and holding at that temperature for 1.4-1.6 hours, then heating to 800°C at a rate of 7-8°C / min and calcining for 3-4 hours.

[0035] In this invention, the first stage of calcination aims to remove residual free and bound water in the precursor, preventing rapid evaporation of moisture in the subsequent high-temperature stage and thus avoiding cracks inside the ceramsite. This process enables the precursor to form a preliminary rigid structure, laying the foundation for subsequent high-temperature sintering. The second stage of calcination is used to construct a glass-crystal composite framework, significantly improving the compressive strength of the ceramsite. The pre-reserved pores formed after the decomposition of wood chips are interconnected with the natural pores of biochar, forming a multi-level pore structure at the micron-nano scale, providing sufficient channels for pollutant adsorption. In addition, high-temperature calcination keeps the carbon structure of biochar stable, further exposing the active sites of rare earth oxides and metal oxides in the tailings, ensuring that the final product has excellent adsorption performance.

[0036] This invention provides a porous ceramic particle adsorbent material prepared by the aforementioned preparation method.

[0037] The present invention also provides an application of the porous ceramic adsorbent material described above in the adsorption of heavy metal ions and / or organic pollutants in water, wherein the heavy metal ions include one or more of lead ions, cadmium ions and chromium ions, and the organic pollutants include one or more of phenol, methyl orange and methylene blue.

[0038] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0039] Example 1

[0040] 1g of corn stalks were acid-washed with 8mL of 2mol / L hydrochloric acid while stirring at a speed of 200r / min. The acid washing was completed after 4h and the pH was washed to 7.0. Then, the stalks were dried at 110℃ for 6h to obtain acidified biochar. Rare earth tailings with a particle size of 100 μm were ball-milled in a planetary ball mill at a speed of 280 r / min. The ball-to-material ratio was 10:1. After 2 hours of ball milling, the tailings were passed through a 150-mesh sieve to obtain fine tailings powder. Acidified biochar, tailings fine powder, attapulgite and wood chips in a mass ratio of 10:45:20:10 were mixed at a speed of 300 r / min for 20 min to obtain a mixture. Add 5g of bentonite and 30g of water to 100g of mixture, knead at 25℃ for 30min, and then extrude using an SJ35 single screw extruder with a screw speed of 45r / min, a die head temperature of 35℃, a feed rate of 15kg / h, and a cutter speed of 90r / min to obtain a ceramic particle precursor with a particle size of 5mm. The ceramsite precursor was first heated to 250℃ at a rate of 3℃ / min under a nitrogen atmosphere and held at that temperature for 1.5h. Then, it was heated to 750℃ at a rate of 8℃ / min and calcined for 3h. Finally, it was cooled in the furnace to obtain porous ceramsite adsorbent material.

[0041] The performance of the porous ceramsite adsorbent material prepared in Example 1 was tested. The test results showed that the specific surface area (BET adsorption method) was 286 m². 2 / g, compressive strength (universal testing machine, loading rate 1mm / min) is 6.2MPa, Pb 2+ The adsorption capacity (100 mg / L Pb(NO3)2 solution, adsorption time 120 min) was 125 mg / g, the methyl orange adsorption capacity (50 mg / L methyl orange solution, adsorption time 120 min) was 85 mg / g, and the recovery rate (ceramsite collected after standing sedimentation for 30 min, and the mass recovery rate calculated) was 96.3%.

[0042] Example 2

[0043] 1g of wheat straw was acid-washed with 6mL of 3mol / L hydrochloric acid while stirring at a speed of 250r / min. The acid washing was completed after 3h and the pH was washed to 6.8. Then it was dried at 105℃ for 5h to obtain acidified biochar. Rare earth tailings were ball-milled in a planetary ball mill at a speed of 300 r / min with a ball-to-material ratio of 11:1. After 1.5 hours of ball milling, the tailings were passed through a 200-mesh sieve to obtain fine tailings powder. Acidified biochar, tailings fine powder, attapulgite and wood chips in a mass ratio of 15:50:15:8 were mixed at a speed of 400 r / min for 15 min to obtain a mixture. Add 4g of sodium carboxymethyl cellulose and 25g of water to 100g of the mixture, knead at 28℃ for 25min, and then extrude it using an SJ35 single-screw extruder with a screw speed of 50r / min, a die head temperature of 40℃, a feed rate of 15kg / h, and a cutter speed of 100r / min to obtain a ceramic particle precursor with a particle size of 8mm. The ceramsite precursor was first heated to 280℃ at a rate of 4℃ / min under a nitrogen atmosphere and held at that temperature for 1.0 h. Then, it was heated to 800℃ at a rate of 10℃ / min and calcined for 2.5 h. Finally, it was cooled in the furnace to obtain porous ceramsite adsorbent material.

[0044] The performance of the porous ceramic adsorbent material prepared in Example 2 was tested. The test results showed that the specific surface area was 312 m². 2 / g, compressive strength is 5.8MPa, Pb 2+The adsorption capacity was 118 mg / g, the adsorption capacity of methyl orange was 89 mg / g, and the recovery rate was 95.7%.

[0045] Example 3

[0046] Compared with Example 1, the difference is that in Example 3, 3g of sodium silicate, 2g of bentonite and 35g of water were added to 100g of the mixture.

[0047] The performance of the porous ceramic adsorbent material prepared in Example 3 was tested. The test results showed that the specific surface area was 265 m². 2 / g, compressive strength is 6.5MPa, Pb 2+ The adsorption capacity was 98 mg / g, the adsorption capacity of methyl orange was 78 mg / g, and the recovery rate was 97.1%.

[0048] Comparative Example 1

[0049] Compared with Example 1, the difference is that acidified biochar was not added in Comparative Example 1, and tailings fine powder, attapulgite and wood chips were mixed in a mass ratio of 60:25:10.

[0050] The porous ceramsite adsorbent material prepared in Comparative Example 1 was used as a sample for performance testing. The test results showed a specific surface area of ​​128 m². 2 / g, compressive strength is 4.2MPa, Pb 2+ The adsorption capacity was 45 mg / g, the adsorption capacity of methyl orange was 32 mg / g, and the recovery rate was 94.5%.

[0051] Comparative Example 2

[0052] Compared with Example 1, the difference is that tailings fine powder was not added in Comparative Example 2, and acidified biochar, attapulgite and wood chips were mixed in a mass ratio of 50:30:15.

[0053] The porous ceramsite adsorbent material prepared in Comparative Example 2 was used as a sample for performance testing. The test results showed a specific surface area of ​​220 m². 2 / g, compressive strength is 2.1MPa, Pb 2+ The adsorption capacity was 68 mg / g, the adsorption capacity of methyl orange was 65 mg / g, and the recovery rate was 82.3%.

[0054] Comparative Example 3

[0055] Compared with Example 1, the difference is that no sawdust was added in Comparative Example 3, and acidified biochar, tailings powder and attapulgite were mixed in a mass ratio of 10:45:20.

[0056] The porous ceramic adsorbent material prepared in Comparative Example 3 was used as a sample for performance testing. The test results showed a specific surface area of ​​156 m².2 / g, compressive strength is 6.0MPa, Pb 2+ The adsorption capacity was 72 mg / g, the adsorption capacity of methyl orange was 48 mg / g, and the recovery rate was 95.1%.

[0057] Comparative Example 4

[0058] Compared with Example 1, the difference is that Comparative Example 4 uses a single heating rate for calcination, directly heating to 750°C at 5°C / min and calcining for 4.5 hours.

[0059] The porous ceramsite adsorbent material prepared in Comparative Example 4 was used as a sample for performance testing. The test results showed a specific surface area of ​​205 m². 2 / g, compressive strength is 3.8MPa, Pb 2+ The adsorption capacity was 85 mg / g, the adsorption capacity of methyl orange was 62 mg / g, and the recovery rate was 88.7%.

[0060] Comparative Example 5

[0061] Compared with Example 1, the difference is that in Comparative Example 5, the corn stalks were directly dried without acid washing.

[0062] The porous ceramic adsorbent material prepared in Comparative Example 5 was used as a sample for performance testing. The test results showed a specific surface area of ​​185 m². 2 / g, compressive strength is 5.0MPa, Pb 2+ The adsorption capacity was 75 mg / g, the adsorption capacity of methyl orange was 55 mg / g, and the recovery rate was 95.2%.

[0063] As can be seen from the above embodiments, the present invention provides a porous ceramsite adsorbent material utilizing straw biochar and rare earth tailings, its preparation method, and its application, comprising the following steps: sequentially acid-washing and drying the straw biochar to obtain acidified biochar; ball-milling the rare earth tailings to obtain tailings fine powder; mixing the acidified biochar, tailings fine powder, attapulgite, and sawdust to obtain a mixture; adding a binder and water to the mixture, and sequentially kneading and extruding to obtain a ceramsite precursor; calcining the ceramsite precursor under a protective atmosphere to obtain the porous ceramsite adsorbent material. As can be seen from Examples 1-3 and Comparative Examples 1-5, the adsorbent material prepared by the method of the present invention possesses the following excellent properties: a specific surface area higher than 265 m². 2 / g, compressive strength not less than 5.8MPa, Pb 2+With an adsorption capacity of not less than 98 mg / g and a recovery rate of greater than 95.7%, this invention is significantly superior to the comparative example. This invention utilizes a ternary composite of acidified biochar, rare earth tailings, and attapulgite, combined with wood chip pore-forming, segmented calcination, and acid washing pretreatment techniques. This effectively solves the technical challenges of traditional adsorption materials in terms of adsorption capacity, strength, and recovery. It not only achieves waste-to-waste treatment (such as the resource utilization of straw and tailings) but also ensures the material's potential for industrial applications (high strength, easy recovery, and flexible processing).

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing porous ceramsite adsorbent material using straw biochar and rare earth tailings, characterized in that, Includes the following steps: 1) The straw biochar is sequentially acid-washed and dried to obtain acidified biochar; 2) Ball mill the rare earth tailings to obtain fine tailings powder; 3) Mix acidified biochar, tailings fine powder, attapulgite, and wood chips to obtain a mixture; 4) Add binder and water to the mixture, and knead and extrude in sequence to obtain the ceramsite precursor; 5) The ceramsite precursor is calcined under a protective atmosphere to obtain porous ceramsite adsorbent material.

2. The method for preparing porous ceramsite adsorbent material using straw biochar and rare earth tailings according to claim 1, characterized in that, In step 1), the pickling reagent used is hydrochloric acid or sulfuric acid solution, and the molar concentration of hydrochloric acid or sulfuric acid solution is 1~5 mol / L. The pickling is carried out by stirring at a speed of 100-300 r / min for 2-6 h.

3. The method for preparing porous ceramsite adsorbent material using straw biochar and rare earth tailings according to claim 2, characterized in that, In step 1), the mass-to-volume ratio of straw biochar to acid washing reagent is 1g:5~10mL; The drying temperature is 100~120℃, and the drying time is 4~8h.

4. The method for preparing porous ceramsite adsorbent material using straw biochar and rare earth tailings according to claim 3, characterized in that, In step 2), the ball-to-material ratio of the ball mill is 8~12:1, the ball mill speed is 200~350 r / min, and the ball milling time is 1~3 h; The particle size of the tailings fine powder is ≤100μm.

5. The method for preparing porous ceramsite adsorbent material using straw biochar and rare earth tailings according to claim 1, 2, or 4, characterized in that, In step 3), the mass ratio of acidified biochar, tailings fine powder, attapulgite and wood chips is 5~20:30~60:10~30:5~15; The mixing is carried out by stirring at a speed of 200-400 r / min for a time of 10-30 min.

6. The method for preparing porous ceramsite adsorbent material using straw biochar and rare earth tailings according to claim 5, characterized in that, In step 4), the mass ratio of the mixture, binder and water is 100:3~10:20~40; The binder is one or more of cement, sodium silicate, bentonite, starch, and sodium carboxymethyl cellulose.

7. The method for preparing porous ceramsite adsorbent material using straw biochar and rare earth tailings according to claim 6, characterized in that, In step 4), the kneading temperature is 20~30℃ and the kneading time is 15~40min; During the extrusion molding process, the screw speed is 30~60 r / min, the temperature is 25~50℃, and the feeding speed is 10~20 kg / h; The particle size of the ceramsite precursor is 3~10mm.

8. The method for preparing porous ceramsite adsorbent material using straw biochar and rare earth tailings according to claim 6 or 7, characterized in that, In step 5), the protective atmosphere is nitrogen or argon. The calcination process involves first heating the temperature to 200-300℃ at a rate of 2-5℃ / min and holding it at that temperature for 1-2 hours, then heating the temperature to 700-900℃ at a rate of 5-10℃ / min and calcining for 2-5 hours.

9. A porous ceramic adsorbent material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the porous ceramic adsorbent material according to claim 9 in the adsorption of heavy metal ions and / or organic pollutants in water, characterized in that, The heavy metal ions include one or more of lead ions, cadmium ions and chromium ions, and the organic pollutants include one or more of phenol, methyl orange and methylene blue.