A permeable concrete brick loaded with metal-organic framework material and preparation method thereof

Abstract

The present invention discloses a kind of permeable concrete brick of load metal organic framework material and its preparation method, the method comprises the following steps: a silicon aluminum material is mixed with an alkali activator to prepare a geopolymer slurry, an organic amine reagent is added, and the modified geopolymer slurry is obtained by stirring evenly after mixing; an aggregate is added to the modified geopolymer slurry, and after stirring evenly, it is loaded into a test mold, and demoulding is obtained after standing for 1 2d to obtain a geopolymer permeable concrete brick, a metal salt solution is evenly sprayed on the geopolymer permeable concrete brick, and steam curing is performed for 3 5h before taking it out; an organic ligand solution is evenly sprayed on the geopolymer permeable concrete brick after curing, and then steam curing is performed for 18 22h. After curing is completed, it is taken out and dried in an oven at 80 120 ℃ for 20 30h to obtain a permeable concrete brick of load metal organic framework material. The permeable concrete brick prepared by the present invention has good adsorption efficiency and can give play to excellent water purification function in actual application.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials, and in particular relates to a permeable concrete brick loaded with a metal-organic framework material and a preparation method thereof. Background Art

[0002] With the rapid development of industries such as metal electroplating facilities, mining operations, fertilizer industry, tanneries, batteries, paper industry and pesticides, heavy metal wastewater is increasingly discharged into the environment directly or indirectly. Wastewater contaminated by heavy metals entering the environment will have serious impacts on ecosystems and human health.

[0003] Pervious concrete is composed of interstitially graded coarse aggregate bonded to a cement paste, sometimes with the addition of chemical admixtures or supplementary cementitious materials. Because pervious concrete contains little or no fine aggregate, its structure contains numerous open voids, allowing large quantities of water and air to flow through these interconnected macroscopic voids. Pervious concrete offers numerous environmental benefits, including controlling stormwater runoff, restoring groundwater supplies, improving water quality, and reducing water and soil pollution. The two most essential components of pervious concrete are cement paste and aggregate, both of which have the ability to remove pollutants from solution. The water purification capacity of pervious concrete is significantly influenced by the adsorption capacity of its paste. This is because the strongly alkaline conditions (pH > 12) formed by cement hydration lead to metal precipitation or adsorption of heavy metal ions to cement hydration products, such as calcium-silica monohydrate (CSH) gel. Therefore, pervious concrete has a certain water purification capacity, and its adsorption capacity for heavy metals can be enhanced by modifying its paste, thereby improving water purification effectiveness.

[0004] Metal-organic frameworks (MOFs, also known as porous coordination polymers or PCPs) are an emerging class of porous materials composed of metal-containing nodes (also known as secondary building units or SBUs) and organic linkers, which are fixed in place by multidentate organic molecules through coordination bonds to form a cage-like structure. Due to the high surface area, adjustable pore size, open metal sites and ordered crystal structure of MOFs (which can be further adjusted by changing the type and nature of the metal and ligands and post-synthesis modification), MOFs can be used in a variety of applications. MOFs are widely used in energy storage, carbon fixation, liquid separation, purification, gas storage, photoluminescence, heterogeneous catalysis, drug delivery, sensing and adsorption. In addition, MOFs can be synthesized on a large scale using low-cost and simple methods. In the past decade, various MOF materials have been reported to be effective in the adsorption and removal of heavy metal ions, including Pb 2+ 、Cd 2+ 、Hg 2+ Cr 3+ Cr 6+ 、As 3+ and As 5+The tunable physicochemical properties and highly ordered porous structure of MOFs make them promising next-generation adsorption materials for the effective removal of heavy metal ions. Currently, there is considerable research on MOFs as adsorbents, and research on MOF composites is also increasing. Existing studies have shown that loading MOFs onto other materials can help them achieve more efficient adsorption. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a permeable concrete brick loaded with metal-organic framework material and a preparation method thereof in response to the shortcomings of the existing technology. The permeable concrete brick provided by the present invention has good adsorption efficiency and can exert excellent water purification function in actual use.

[0006] The technical solution adopted by the present invention to solve the above-mentioned problems is:

[0007] A method for preparing a permeable concrete brick loaded with a metal-organic framework material comprises the following steps:

[0008] A geopolymer slurry is prepared by mixing a silicon-aluminum material with an alkali activator, and an organic amine reagent is added to the geopolymer slurry, and the mixture is stirred uniformly to obtain a modified geopolymer slurry;

[0009] Aggregate is added to the modified geopolymer slurry, and after being stirred evenly, the slurry is loaded into a test mold, and after standing for 1-2 days, the slurry is demoulded to obtain a geopolymer permeable concrete brick, and a metal salt solution is evenly sprayed on the geopolymer permeable concrete brick, and the brick is steam-cured for 3-5 hours before being taken out;

[0010] The organic ligand solution is evenly sprayed on the cured geopolymer permeable concrete brick, and then steam cured for 18-22 hours. After the curing is completed, the brick is taken out and dried in an oven at 80-120° C. for 20-30 hours to obtain the permeable concrete brick loaded with the metal-organic framework material.

[0011] In the above scheme, the organic ligand solution is a mixture of an organic ligand and an organic solvent, wherein the molar ratio of the organic ligand to the organic solvent in the organic ligand solution is 1:(10-15); the organic ligand is one of trimesic acid, terephthalic acid, 2-methylimidazole, benzimidazole, and imidazole; and the organic solvent is one of methanol, ethanol, and dimethylamide.

[0012] In the above scheme, the metal salt solution includes a metal salt and the organic solvent, wherein the molar ratio of the metal salt to the organic solvent in the metal salt solution is 1:(8-17); wherein the metal salt is one of aluminum nitrate, aluminum chloride, cobalt nitrate hexahydrate, zinc nitrate, and zinc chloride.

[0013] In the above scheme, the molar ratio of the metal salt to the organic ligand is (0.25-5):1.

[0014] In the above scheme, the mass ratio of the silica-alumina material, the alkaline activator and the organic amine reagent is (3-3.2):(0.9-1):(0.2-0.4); the volume ratio of the permeable concrete brick slurry is 0.39-0.48, that is, the volume ratio of the modified polymer slurry to the aggregate is (0.39-0.48):1; the water-cement ratio of the permeable concrete brick is 0.43-0.46.

[0015] In the above scheme, the silicon-alumina material is one of fly ash, metakaolin, slag, coal gangue, steel slag, or a mixture of any of them; the aggregate is crushed stone or pebbles for construction, wherein the particle size of the aggregate is 4.75-16 mm and single graded.

[0016] In the above scheme, the alkaline activator is one of sodium hydroxide, sodium silicate, potassium hydroxide, potassium silicate or a mixed aqueous solution of any of them; the modulus M(SiO2) / n(Na2O) of the alkaline activator is 0.5-2, and the alkali equivalent is 5-20%.

[0017] In the above solution, the organic amine reagent is one of ethylenediamine reagent and propylenediamine reagent; the purity of the organic amine reagent is 98wt%-99wt%.

[0018] In the above scheme, the steam curing conditions are: relative humidity greater than 90% and temperature of 40-80°C.

[0019] The present invention also claims protection for the permeable concrete brick loaded with metal-organic framework material prepared by the method for preparing the permeable concrete brick loaded with metal-organic framework material.

[0020] In the present invention, there are more active functional groups in the geopolymer, but there is a lack of functional groups that can be directly connected to MOF, so it is difficult to load MOF by direct use. The present invention first modifies the geopolymer slurry with an organic amine reagent to load functional groups that can better connect to MOF, and then sprays organic ligands and metal salt solutions separately during the steam curing process of permeable concrete bricks to generate MOF structures during the steam curing process and connect with the permeable concrete bricks. The improvement of the water purification function of MOF in permeable concrete is mainly related to the special structure of MOF itself. It is woven by metal ions and secondary structural blocks (organic ligands) through strong coordination bonds (network synthesis), thereby forming an open framework with high permanent porosity. When the MOF material is loaded on the cement slurry, thanks to the unique network structure of the MOF material, a large number of pores will appear in the cement slurry. The higher specific surface area and pores are conducive to the adsorption of heavy metal ions and other harmful substances by the cement slurry loaded with MOF material. There are a large number of active groups such as hydroxyl groups on the surface of geopolymers. Adding organic solvents can link functional groups that are more conducive to heavy metal binding to the geopolymer, making the geopolymer-loaded MOF structure simpler. On the other hand, modification with organic amine reagents can improve the mechanical properties of the geopolymer. Reusing the steam curing process of concrete bricks, the MOF structure is loaded on the permeable concrete by spraying metal salt solution and organic ligand solution. The two form a strong bond, and the raw material preparation cost is low and the production process is simple. Therefore, loading metal-organic framework materials (MOFs) on permeable concrete helps to improve the water purification performance of permeable concrete and can greatly increase its ability to adsorb heavy metal ions and other harmful substances, which has a relatively broad application prospect.

[0021] Compared with the existing technology, the beneficial effects of the present invention are:

[0022] (1) The present invention provides a method for preparing a permeable concrete brick loaded with a metal-organic framework material. The MOF material is combined with the permeable concrete. The structural characteristics of the MOF are utilized to enhance the adsorption of heavy metal ions by the slurry, thereby improving the water purification performance of the permeable concrete and contributing to environmental protection. Simultaneously, the structure of the geopolymer slurry provides a certain degree of protection for the MOF material, ensuring its adsorption.

[0023] (2) The preparation method of a permeable concrete brick loaded with metal-organic framework material provided by the present invention is simple to operate, has a concise work flow, and has low raw material cost, and can be well applied in actual production. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be fully and clearly described below in conjunction with specific embodiments, but the described embodiments are only some embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] In a specific embodiment, the ethylenediamine reagent, cobalt nitrate hexahydrate, zinc chloride, and ethanol used are purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; 2-methylimidazole, benzimidazole, and imidazole are purchased from Wuhan Puluofu Biotechnology Co., Ltd.; water uses laboratory-made deionized water; sodium silicate is purchased from Jiashan County Yourui Refractory Material Co., Ltd. to produce SP38 water glass, whose modulus (i.e., the molar ratio of SiO2 and Na2O) is 3.3, the Na2SiO3 content is 35.5%, the Na2O content is 8.53%, and the SiO2 content is 26.98%; sodium hydroxide is a white granular solid particle purchased from Sinopharm Chemical Reagent Co., Ltd., and its content is ≥96%; the slag used in the experiment is S95-grade granulated blast furnace slag powder produced by a company in Wuhan.

[0026] Example 1

[0027] Take 47.70g NaOH, 95.69g SP38 water glass (Na2SiO3 content is 35.5%), and 133.03g water to prepare an alkaline activator, take 451.79g slag, add the alkaline activator thereto, mix well, then add 45.53g ethylenediamine reagent, and stir evenly to obtain a modified polymer slurry.

[0028] 1655 g of construction gravel with a particle size of 9.5-13.2 mm was added to the mixed modified geopolymer slurry, and the mixture was placed in a stirring pot and stirred thoroughly for 1-2 minutes.

[0029] Pour the concrete into a 100mm×100mm×100mm cubic test mold and remove it from the mold after it has been left to stand for 1 day.

[0030] Take 5.82g of cobalt nitrate hexahydrate and 10ml of ethanol to prepare cobalt nitrate solution, spray it evenly on the six sides of the concrete brick, send the concrete brick to the curing room for steam curing for 4 hours and then take it out.

[0031] An organic ligand solution was prepared by mixing 2.76g of 2-methylimidazole with 20ml of ethanol. The solution was then evenly sprayed onto the six surfaces of the permeable concrete brick. The brick was then steam-cured for 20 hours. After removal, the brick was dried in an 85°C oven for 24 hours to obtain the metal-organic framework-loaded permeable concrete brick. The steam curing conditions were: relative humidity greater than 90% and temperature 60°C.

[0032] Example 2

[0033] Take 47.70g NaOH, 95.69g SP38 water glass (Na2SiO3 content is 35.5%), and 133.03g water to prepare an alkaline activator, take 451.79g slag, add the alkaline activator thereto, mix well, then add 45.53g ethylenediamine reagent, and stir evenly to obtain a modified polymer slurry.

[0034] 1655 g of construction gravel with a particle size of 9.5-13.2 mm was added to the mixed modified geopolymer slurry, and the mixture was placed in a stirring pot and stirred thoroughly for 1-2 minutes.

[0035] Pour the concrete into a 100mm×100mm×100mm cubic test mold and remove it from the mold after it has been left to stand for 1 day.

[0036] Prepare zinc chloride solution by mixing 1.96g zinc chloride with 10ml ethanol, and spray it evenly on the six sides of the concrete brick. Send the concrete brick to the curing room for steam curing for 4 hours and then take it out.

[0037] An organic ligand solution was prepared by mixing 2.29g of imidazole with 20ml of ethanol. The solution was then evenly sprayed onto the six surfaces of the permeable concrete brick. The brick was then steam-cured for 20 hours and then dried in an 85°C oven for 24 hours to produce the metal-organic framework-loaded permeable concrete brick. Steam curing conditions were: relative humidity greater than 90% and temperature 60°C.

[0038] Example 3

[0039] Take 47.70g NaOH, 95.69g SP38 water glass (Na2SiO3 content is 35.5%), and 133.03g water to prepare an alkaline activator, take 451.79g slag, add the alkaline activator thereto, mix well, then add 45.53g ethylenediamine solution, and stir evenly to obtain a modified polymer slurry.

[0040] 1655 g of construction gravel with a particle size of 9.5-13.2 mm was added to the mixed modified geopolymer slurry, and the mixture was placed in a stirring pot and stirred thoroughly for 1-2 minutes.

[0041] Pour the concrete into a 100mm×100mm×100mm cubic test mold and remove it from the mold after it has been left to stand for 1 day.

[0042] Prepare a cobalt nitrate solution by mixing 5.68 g of cobalt nitrate hexahydrate with 10 ml of ethanol, and spray the solution evenly on the six sides of the concrete brick. Send the concrete brick to the curing room for steam curing for 4 hours and then take it out.

[0043] An organic ligand solution was prepared by mixing 3.97g of benzimidazole with 20ml of ethanol. The solution was then evenly sprayed onto the six surfaces of the permeable concrete brick. The brick was then steam-cured for 20 hours and then dried in an 85°C oven for 24 hours to produce the metal-organic framework-loaded permeable concrete brick. Steam curing conditions were: relative humidity greater than 90% and temperature 60°C.

[0044] Comparative Example 1

[0045] The permeable concrete bricks of this comparative example were prepared in the same steps as those of Example 1, except that the ethylenediamine reagent was not mixed into the geopolymer and the metal salt solution and the organic ligand solution were not sprayed during steam curing. Thus, the permeable concrete bricks were prepared using ordinary geopolymer permeable concrete.

[0046] Comparative Example 2

[0047] The permeable concrete bricks of this comparative example were prepared in the same steps as those of Example 1, except that the ethylenediamine reagent was not mixed into the geopolymer. That is, the geopolymer permeable concrete was prepared by spraying the metal salt solution and the organic ligand solution without modification by ethylenediamine.

[0048] The permeable concrete brick samples prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to a water permeability test and a 28-day compressive strength test. The results are shown in Table 1, and all of them meet the permeable concrete performance requirements.

[0049] Table 1

[0050] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Permeability coefficient (mm / s) 11.76 11.59 11.62 12.09 11.88 28d compressive strength (MPa) 14.95 14.64 14.83 15.20 15.10

[0051] The permeable concrete brick samples prepared in Examples 1-3 and Comparative Example were placed on Pb 2+ The static adsorption test of Pb(OH)2 with a concentration of 500 mg / L was carried out. 2+ Residual concentration to determine Pb 2+ The removal rate is used to judge the water purification effect. The experimental results of the embodiment and the comparative example are shown in Table 2:

[0052] Table 2

[0053] Test items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 <![CDATA[Pb 2+ Removal rate]]> 96.5％ 96.7％ 97.1％ 72.6％ 78.3％

[0054] In summary, the permeable concrete brick loaded with metal-organic framework material provided by the present invention has good adsorption efficiency and can exert excellent water purification function in practical application.

[0055] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art who, within the technical scope disclosed by the present invention, makes equivalent substitutions or changes based on the technical solutions and improved concepts of the present invention shall be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a permeable concrete brick loaded with a metal-organic framework material, characterized in that: The following steps are involved: A geopolymer slurry is prepared by mixing a silicon-aluminum material with an alkali activator, and an organic amine reagent is added to the geopolymer slurry, and the mixture is stirred uniformly to obtain a modified geopolymer slurry; Aggregate is added to the modified geopolymer slurry, and after being stirred evenly, the slurry is loaded into a test mold, and after standing for 1-2 days, the slurry is demoulded to obtain a geopolymer permeable concrete brick, and a metal salt solution is evenly sprayed on the geopolymer permeable concrete brick, and the brick is steam-cured for 3-5 hours before being taken out; The organic ligand solution is evenly sprayed on the cured geopolymer permeable concrete brick, and then steam-cured for 18-22 hours. After the curing is completed, the brick is taken out and dried in an oven at 80-120° C. for 20-30 hours to obtain the permeable concrete brick loaded with the metal-organic framework material; The organic amine reagent is one of ethylenediamine reagent and propylenediamine reagent; The mass ratio of the silicon-aluminum material, the alkaline activator and the organic amine reagent is (3-3.2): (0.9-1): (0.2-0.4).

2. The method for preparing a permeable concrete brick loaded with a metal-organic framework material according to claim 1, characterized in that: The organic ligand solution is a mixture of an organic ligand and an organic solvent, wherein the molar ratio of the organic ligand to the organic solvent in the organic ligand solution is 1:(10-15); the organic ligand is one of trimesic acid, terephthalic acid, 2-methylimidazole, benzimidazole, and imidazole; and the organic solvent is one of methanol, ethanol, and dimethylamide.

3. The method for preparing a permeable concrete brick loaded with a metal-organic framework according to claim 2, characterized in that: The metal salt solution comprises a metal salt and the organic solvent, wherein the molar ratio of the metal salt to the organic solvent in the metal salt solution is 1:(8-17); wherein the metal salt is one of aluminum nitrate, aluminum chloride, cobalt nitrate hexahydrate, zinc nitrate, and zinc chloride.

4. The method for preparing a permeable concrete brick loaded with a metal-organic framework according to claim 3, characterized in that: The molar ratio of the metal salt to the organic ligand is (0.25-5):

1.

5. The method for preparing a permeable concrete brick loaded with a metal-organic framework according to claim 1, characterized in that: The permeable concrete brick mortar ratio is 0.39-0.48, and the water-cement ratio is 0.43-0.

46.

6. The method for preparing a permeable concrete brick loaded with a metal-organic framework according to claim 1, characterized in that: The alumina-silica material is one of fly ash, metakaolin, slag, coal gangue, and steel slag, or a mixture of any of the above. The aggregate is crushed stone or pebbles for construction. The aggregate has a particle size of 4.75-16 mm and is single-graded.

7. The method for preparing a permeable concrete brick loaded with a metal-organic framework according to claim 1, characterized in that: The alkaline activator is one of sodium hydroxide, sodium silicate, potassium hydroxide, potassium silicate or a mixed aqueous solution of any of them; the modulus M(SiO2) / n(Na2O) of the alkaline activator is 0.5-2, and the alkali equivalent is 5-20%.

8. The method for preparing a permeable concrete brick loaded with a metal-organic framework according to claim 1, characterized in that: The purity of the organic amine reagent is 98 wt %-99 wt %.

9. The method for preparing a permeable concrete brick loaded with a metal-organic framework according to claim 1, characterized in that: The steam curing conditions are: relative humidity greater than 90% and temperature of 40-80°C.

10. A permeable concrete brick loaded with a metal-organic framework material, prepared by the method for preparing a permeable concrete brick loaded with a metal-organic framework material according to any one of claims 1 to 9.