Coal gangue-based 4A molecular sieve composite adsorption material and preparation method thereof

Abstract

The invention relates to the field of adsorption materials, in particular to a coal gangue-based 4A molecular sieve composite adsorption material and a preparation method thereof, and is used for solving the problems that an existing coal gangue-based 4A molecular sieve adsorption material is poor in adsorption capacity and not ideal in heavy metal ion removal effect. According to the preparation method, coal gangue is used for preparing the coal gangue-based 4A molecular sieve, resource utilization of the coal gangue is achieved, the production cost of the adsorption material is reduced, meanwhile, pollution of the coal gangue to the environment is reduced, the coal gangue-based 4A molecular sieve composite adsorption material provides a large number of adsorption sites through the coal gangue-based 4A molecular sieve, and the adsorption efficiency is improved. The nano zero-valent iron is utilized to play a reducing role, a large number of carboxyl groups are utilized to chelate metal ions, and under the synergistic effect of the nano zero-valent iron, the carboxyl groups and the metal ions, effective adsorption and removal of heavy metal ions in a water body are jointly achieved, so that the overall purification effect is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of adsorption materials, and particularly relates to a coal gangue-based 4A zeolite composite adsorption material and a preparation method thereof. Background Art

[0002] As the main by-product generated during coal mining and coal washing, the main components of coal gangue include silicate, aluminosilicate and a small amount of various elements such as iron and magnesium. It has long been regarded as waste. Long-term open-air stacking not only occupies land resources, but also causes environmental pollution to soil, water source and air. As a material with excellent adsorption performance, 4A zeolite has been widely used in water treatment, air purification and other aspects.

[0003] The silicon-aluminum oxides rich in coal gangue can theoretically be used as a natural raw material for preparing zeolite materials. Preparing 4A zeolite from coal gangue can not only reduce environmental pollution, but also improve resource utilization rate. However, the 4A zeolite prepared from existing coal gangue has poor adsorption capacity, low adsorption efficiency when used as an adsorbent for metal ions in water, and the removal effect on heavy metal ions is not ideal.

[0004] Therefore, it is of great practical significance to develop a coal gangue-based 4A zeolite composite adsorption material and a preparation method thereof. Summary of the Invention

[0005] In order to overcome the above technical problems, the purpose of the present invention is to provide a coal gangue-based 4A zeolite composite adsorption material and a preparation method thereof, which solve the problems that the existing coal gangue-based 4A zeolite adsorption material has poor adsorption capacity and unsatisfactory removal effect on heavy metal ions.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A preparation method of a coal gangue-based 4A zeolite composite adsorption material includes the following steps:

[0008] Step a1: Add coal gangue-based 4A zeolite, ferrous sulfate heptahydrate, polyethylene glycol, absolute ethanol and deionized water into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a constant pressure dropping funnel, introduce nitrogen protection, and stir and react at a temperature of 25-30 °C and a stirring rate of 300-400 r / min for 10-20 min. Then, while stirring, gradually dropwise add a sodium borohydride solution, control the dropping rate to be 1-2 drops / s. After the dropping is completed, continue to stir and react for 1-2 h. After the reaction is completed, centrifuge the reaction product, wash the precipitate with distilled water 3-5 times, and then place it in a vacuum drying oven and dry it at a temperature of 60-65 °C for 3-4 h to obtain a zero-valent iron-loaded composite zeolite;

[0009] Step a2: Add absolute ethanol and deionized water into a three-necked flask equipped with a stirrer, a thermometer and a gas pipe. Introduce nitrogen for protection. Stir and react for 3 - 5 min under the conditions of a temperature of 25 - 30 °C and a stirring rate of 300 - 400 r / min. Then adjust the pH to 9 - 9.5 with ammonia water. After that, add the zero-valent iron-loaded composite molecular sieve and continue to stir and react for 20 - 30 min under the condition of heating to 80 - 85 °C. Then add KH-560 silane coupling agent and continue to stir and react for 2 - 3 h. After the reaction is completed, centrifuge the reaction product, place the precipitate in a vacuum drying oven, and dry it for 2 - 3 h under the condition of a temperature of 60 - 65 °C to obtain the epoxy composite molecular sieve;

[0010] Step a3: Add the epoxy composite molecular sieve, iminodiacetonitrile and anhydrous tetrahydrofuran into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 10 - 15 min under the conditions of a temperature of 25 - 30 °C and a stirring rate of 300 - 400 r / min. Then heat to 60 - 65 °C and continue to stir and react for 5 - 6 h. After the reaction is completed, cool the reaction product to room temperature, then centrifuge it, wash the precipitate with anhydrous acetone for 3 - 5 times, and then place it in a vacuum drying oven and dry it for 1 - 2 h under the condition of a temperature of 60 - 65 °C to obtain the cyano composite molecular sieve;

[0011] Step a4: Add the cyano composite molecular sieve, potassium hydroxide, absolute ethanol and deionized water into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 10 - 15 min under the conditions of a temperature of 25 - 30 °C and a stirring rate of 300 - 400 r / min. Then heat to 95 - 100 °C and continue to stir and react for 20 - 30 h. After the reaction is completed, cool the reaction product to room temperature, then pour it into a hydrochloric acid solution, then let it stand for 3 - 5 h, then centrifuge it, wash the precipitate with distilled water for 3 - 5 times, and then place it in a vacuum drying oven and dry it for 8 - 10 h under the condition of a temperature of 50 - 55 °C to obtain the coal gangue-based 4A molecular sieve composite adsorbent material.

[0012] As a further scheme of the present invention: The dosage ratio of the coal gangue-based 4A molecular sieve, ferrous sulfate heptahydrate, polyethylene glycol, absolute ethanol, deionized water and sodium borohydride solution in step a1 is 2 g: 3 - 3.5 g: 2 - 2.2 mL: 40 - 50 mL: 40 - 50 mL: 50 - 60 mL.

[0013] As a further scheme of the present invention: The polyethylene glycol in step a1 is PEG-400; the molar concentration of the sodium borohydride solution is 0.03 - 0.05 mol / L.

[0014] As a further solution of the present invention: the dosage ratio of the absolute ethanol, deionized water, zero-valent iron-loaded composite molecular sieve, and KH-560 silane coupling agent in step a2 is 80-90 mL: 20-30 mL: 10 g: 0.5-2.5 g.

[0015] As a further solution of the present invention: the mass fraction of the ammonia water in step a2 is 25-27%.

[0016] As a further solution of the present invention: the dosage ratio of the epoxy composite molecular sieve, iminodiacetonitrile, and anhydrous tetrahydrofuran in step a3 is 10 g: 1.8-3.4 g: 90-100 mL.

[0017] As a further solution of the present invention: the dosage ratio of the cyano composite molecular sieve, potassium hydroxide, absolute ethanol, and deionized water in step a4 is 10 g: 35-40 g: 80-90 mL: 80-90 mL.

[0018] As a further solution of the present invention: the mass fraction of the hydrochloric acid solution in step a4 is 20-25%.

[0019] As a further solution of the present invention: the coal gangue-based 4A molecular sieve is prepared by the following steps:

[0020] Step b1: The coal gangue powder is ball-milled and passed through a 200-mesh sieve, then placed in an atmosphere furnace, and low-temperature oxidized at a temperature of 350-370 °C for 1 h, then cooled with the furnace, then added to a hydrochloric acid solution, and stirred and reacted at a temperature of 70-75 °C and a stirring rate of 300-400 r / min for 2-3 h, then centrifuged, the precipitate is washed with distilled water 3-5 times, and then placed in a vacuum drying oven and dried at a temperature of 70-75 °C for 3-4 h to obtain acid-treated coal gangue powder;

[0021] Step b2: The acid-treated coal gangue powder is placed in an atmosphere furnace and heated to a high temperature of 700-750 °C at a heating rate of 5 °C / min for 1.5-2 h, then cooled with the furnace, then sodium carbonate is added, and high-temperature calcined at 800-850 °C for 1.5-2 h, then cooled with the furnace to obtain calcined coal gangue powder;

[0022] Step b3: The calcined coal gangue powder is added to deionized water, then ultrasonically treated at an ultrasonic frequency of 35-45 kHz for 20-60 min, then vacuum filtered, sodium aluminate and sodium hydroxide are added to the filtrate, and the molar ratio of SiO 2 to Al 2 O 3 is adjusted to 2.0, and the molar ratio of Na 2 O to SiO2 The molar ratio is 1.8, and then the mixture is stirred and reacted for 2 - 3 h under the conditions of a temperature of 60 - 65 °C and a stirring rate of 500 - 600 r / min. Then, it is placed in a hydrothermal reaction kettle and hydrothermally crystallized at a temperature of 90 - 95 °C for 5 - 6 h to obtain coal gangue-based 4A zeolite.

[0023] As a further scheme of the present invention: The main chemical components of the coal gangue powder in step b1 are: w(SiO 2 )=59.9%, w(Al 2 O 3 ) = 24.6%, w(Fe 2 O 3 ) = 4.7%, w(TiO 2 ) = 0.94%, w(CaO) = 8.9%, w(MgO) = 0.96% and w(other) = 1.91%, and w(loss on ignition) = 12.86%.

[0024] As a further scheme of the present invention: The dosage ratio of the coal gangue powder to the hydrochloric acid solution in step b1 is 10 g: 60 - 70 mL.

[0025] As a further scheme of the present invention: The molar concentration of the hydrochloric acid solution in step b1 is 6 mol / L.

[0026] As a further scheme of the present invention: The dosage ratio of the acid-treated coal gangue powder to sodium carbonate in step b2 is 10 g: 12 - 13 g.

[0027] As a further scheme of the present invention: The dosage ratio of the calcined coal gangue powder to deionized water in step b3 is 10 g: 120 - 130 mL.

[0028] As a further scheme of the present invention: A coal gangue-based 4A zeolite composite adsorbent material is prepared by the preparation method of the coal gangue-based 4A zeolite composite adsorbent material as described above.

[0029] The beneficial effects of the present invention:

[0030] A coal gangue-based 4A molecular sieve composite adsorbent and its preparation method of the present invention realize the resource utilization of coal gangue by using coal gangue to prepare coal gangue-based 4A molecular sieve, reduce the production cost of the adsorbent, and at the same time reduce the environmental pollution caused by coal gangue. Moreover, the coal gangue-based 4A molecular sieve has a rich pore structure and a large specific surface area, which can provide a large number of adsorption sites. Then, sodium borohydride is used as a reducing agent to convert ferrous ions provided by ferrous sulfate heptahydrate into nano-zero-valent iron, which is then loaded into the micropores inside the coal gangue-based 4A molecular sieve to obtain a zero-valent iron-loaded composite molecular sieve. Nano-zero-valent iron can adsorb a variety of heavy metal ions due to its high specific surface area, strong reducing ability, excellent adsorption property and high reaction activity, which can further improve the adsorption effect. Then, the zero-valent iron-loaded composite molecular sieve is modified with KH-560 silane coupling agent. The grafting effect of KH-560 silane coupling agent enhances the binding force between components, improves the stability of the composite adsorbent, and can also introduce a large number of epoxy groups to obtain an epoxy composite molecular sieve. Then, the epoxy composite molecular sieve reacts with iminodiacetonitrile. The epoxy groups on the epoxy composite molecular sieve react with the imino groups on iminodiacetonitrile, thereby introducing a large number of cyano groups to obtain a cyano composite molecular sieve. Then, the cyano groups on the cyano composite molecular sieve are hydrolyzed to form a large number of carboxyl groups. The large number of carboxyl groups can form stable complexes with heavy metal ions, enhancing the adsorption ability of heavy metal ions, and obtaining a coal gangue-based 4A molecular sieve composite adsorbent. Therefore, the coal gangue-based 4A molecular sieve composite adsorbent uses the coal gangue-based 4A molecular sieve to provide a large number of adsorption sites, uses nano-zero-valent iron to play a reducing role, and uses a large number of carboxyl groups to chelate metal ions. Under the synergistic effect of the three, it jointly realizes the effective adsorption and removal of heavy metal ions in water, thus greatly improving the overall purification effect. Detailed implementation mode

[0031] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

[0032] Example 1:

[0033] This example is a preparation method of a coal gangue-based 4A molecular sieve composite adsorbent, including the following steps:

[0034] Step S1: Grind 10 g of coal gangue powder through a 200-mesh sieve by ball milling, then place it in an atmosphere furnace and oxidize it at a low temperature of 350 °C for 1 h, then cool it with the furnace. After that, add it to 60 mL of hydrochloric acid solution with a molar concentration of 6 mol / L, stir and react at a temperature of 70 °C and a stirring rate of 300 r / min for 2 h, then centrifuge, wash the precipitate with distilled water 3 times, and then place it in a vacuum drying oven and dry it at a temperature of 70 °C for 3 h to obtain acid-treated coal gangue powder;

[0035] Step S2: Place 10 g of acid-treated coal gangue powder in an atmosphere furnace, heat it up to 700 °C at a heating rate of 5 °C / min and calcine it at a high temperature for 1.5 h, then cool it with the furnace. After that, add 12 g of sodium carbonate and calcine it at a high temperature of 800 °C for 1.5 h, then cool it with the furnace to obtain calcined coal gangue powder;

[0036] Step S3: Add 10 g of calcined coal gangue powder to 120 mL of deionized water, then ultrasonically treat it for 20 min under the condition of an ultrasonic frequency of 35 kHz, then vacuum filter. Add sodium aluminate and sodium hydroxide to the filtrate to adjust the molar ratio of SiO 2 to Al 2 O 3 to be 2.0, and the molar ratio of Na 2 O to SiO 2 to be 1.8. Then stir and react at a temperature of 60 °C and a stirring rate of 500 r / min for 2 h, and then place it in a hydrothermal reaction kettle and hydrothermally crystallize at a temperature of 90 °C for 5 h to obtain coal gangue-based 4A zeolite;

[0037] Step S4: Add 2 g of coal gangue-based 4A zeolite, 3 g of ferrous sulfate heptahydrate, 2 mL of polyethylene glycol PEG-400, 40 mL of absolute ethanol, and 40 mL of deionized water to a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant-pressure dropping funnel. Introduce nitrogen for protection and stir and react at a temperature of 25 °C and a stirring rate of 300 r / min for 10 min. Then, while stirring, gradually add dropwise 50 mL of sodium borohydride solution with a molar concentration of 0.03 mol / L, control the dropping rate to be 1 drop / s. After the dropping is completed, continue to stir and react for 1 h. After the reaction is completed, centrifuge the reaction product, wash the precipitate with distilled water 3 times, and then place it in a vacuum drying oven and dry it at a temperature of 60 °C for 3 h to obtain zero-valent iron-loaded composite zeolite;

[0038] Step S5: Add 80 mL of absolute ethanol and 20 mL of deionized water into a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube. Introduce nitrogen for protection. Stir and react for 3 min under the conditions of a temperature of 25 °C and a stirring rate of 300 r / min. Then adjust the pH to 9 with 25% ammonia water. Then add 10 g of zero-valent iron-loaded composite molecular sieve and continue to stir and react for 20 min under the condition of heating to 80 °C. Then add 0.5 g of KH-560 silane coupling agent and continue to stir and react for 2 h. After the reaction is completed, centrifuge the reaction product, place the precipitate in a vacuum drying oven, and dry it for 2 h under the condition of a temperature of 60 °C to obtain epoxy composite molecular sieve;

[0039] Step S6: Add 10 g of epoxy composite molecular sieve, 1.8 g of iminodiacetonitrile and 90 mL of absolute tetrahydrofuran into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 10 min under the conditions of a temperature of 25 °C and a stirring rate of 300 r / min. Then continue to stir and react for 5 h under the condition of heating to 60 °C. After the reaction is completed, cool the reaction product to room temperature, then centrifuge, wash the precipitate with absolute acetone 3 times, then place it in a vacuum drying oven, and dry it for 1 h under the condition of a temperature of 60 °C to obtain cyano composite molecular sieve;

[0040] Step S7: Add 10 g of cyano composite molecular sieve, 35 g of potassium hydroxide, 80 mL of absolute ethanol and 80 mL of deionized water into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 10 min under the conditions of a temperature of 25 °C and a stirring rate of 300 r / min. Then continue to stir and react for 20 h under the condition of heating to 95 °C. After the reaction is completed, cool the reaction product to room temperature, then pour it into a 20% hydrochloric acid solution, then let it stand for 3 h, then centrifuge, wash the precipitate with distilled water 3 times, then place it in a vacuum drying oven, and dry it for 8 h under the condition of a temperature of 50 °C to obtain coal gangue-based 4A molecular sieve composite adsorbent material.

[0041] Example 2:

[0042] This example is a preparation method of a coal gangue-based 4A molecular sieve composite adsorbent material, including the following steps:

[0043] Step S1: Grind 10 g of coal gangue powder through a 200-mesh sieve, then place it in an atmosphere furnace, perform low-temperature oxidation at 360 °C for 1 h, then cool it with the furnace, then add it to 65 mL of hydrochloric acid solution with a molar concentration of 6 mol / L, stir and react at 72 °C and a stirring rate of 350 r / min for 2.5 h, then centrifuge, wash the precipitate with distilled water 4 times, then place it in a vacuum drying oven, and dry it for 3.5 h under the condition of a temperature of 72 °C to obtain acid-treated coal gangue powder;

[0044] Step S2: Place 10 g of acid-treated coal gangue powder in an atmosphere furnace, heat it at a heating rate of 5 °C / min to a high temperature of 725 °C and calcine for 1.5 h, then cool it with the furnace. After that, add 12.5 g of sodium carbonate and calcine at 825 °C for 1.5 h, and then cool it with the furnace to obtain calcined coal gangue powder;

[0045] Step S3: Add 10 g of calcined coal gangue powder to 125 mL of deionized water, then ultrasonically treat it for 40 min under the condition of an ultrasonic frequency of 40 kHz, then vacuum filter. Add sodium aluminate and sodium hydroxide to the filtrate to adjust the molar ratio of SiO 2 to Al 2 O 3 to be 2.0, and the molar ratio of Na 2 O to SiO 2 to be 1.8. Then stir and react at a temperature of 62 °C and a stirring rate of 550 r / min for 2.5 h. After that, place it in a hydrothermal reaction kettle and hydrothermally crystallize at 92 °C for 5.5 h to obtain coal gangue-based 4A zeolite;

[0046] Step S4: Add 2 g of coal gangue-based 4A zeolite, 3.2 g of ferrous sulfate heptahydrate, 2.1 mL of polyethylene glycol PEG-400, 45 mL of absolute ethanol, and 45 mL of deionized water to a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant pressure dropping funnel. Pass in nitrogen for protection and stir and react at a temperature of 28 °C and a stirring rate of 350 r / min for 15 min. Then, while stirring, gradually add 55 mL of sodium borohydride solution with a molar concentration of 0.04 mol / L dropwise, control the dropping rate to be 1 drop / s. After dropping, continue to stir and react for 1.5 h. After the reaction is completed, centrifuge the reaction product, wash the precipitate 4 times with distilled water, and then place it in a vacuum drying oven and dry it at 62 °C for 3.5 h to obtain zero-valent iron-loaded composite zeolite;

[0047] Step S5: Add 85 mL of absolute ethanol and 25 mL of deionized water to a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Pass in nitrogen for protection and stir and react at a temperature of 28 °C and a stirring rate of 350 r / min for 4 min. Then adjust the pH to 9.2 with 26% ammonia water. After that, add 10 g of zero-valent iron-loaded composite zeolite and continue to stir and react at 82 °C for 25 min. Then add 1.5 g of KH-560 silane coupling agent and continue to stir and react for 2.5 h. After the reaction is completed, centrifuge the reaction product, and place the precipitate in a vacuum drying oven and dry it at 62 °C for 2.5 h to obtain epoxy composite zeolite;

[0048] Step S6: Add 10 g of epoxy composite molecular sieve, 2.6 g of iminodiacetonitrile, and 95 mL of anhydrous tetrahydrofuran into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 12 min under the conditions of a temperature of 28 °C and a stirring rate of 350 r / min. Then, continue to stir and react for 5.5 h under the condition of heating to 62 °C. After the reaction is completed, cool the reaction product to room temperature, then centrifuge, wash the precipitate 4 times with anhydrous acetone, and then place it in a vacuum drying oven and dry it for 1.5 h under the condition of a temperature of 62 °C to obtain cyano composite molecular sieve;

[0049] Step S7: Add 10 g of cyano composite molecular sieve, 38 g of potassium hydroxide, 85 mL of anhydrous ethanol, and 85 mL of deionized water into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 12 min under the conditions of a temperature of 28 °C and a stirring rate of 350 r / min. Then, continue to stir and react for 25 h under the condition of heating to 98 °C. After the reaction is completed, cool the reaction product to room temperature, then pour it into a hydrochloric acid solution with a mass fraction of 22%, then let it stand for 4 h, then centrifuge, wash the precipitate 4 times with distilled water, and then place it in a vacuum drying oven and dry it for 9 h under the condition of a temperature of 52 °C to obtain a coal gangue-based 4A molecular sieve composite adsorption material.

[0050] Example 3:

[0051] This example is a preparation method of a coal gangue-based 4A molecular sieve composite adsorption material, including the following steps:

[0052] Step S1: Pass 10 g of coal gangue powder through a 200-mesh sieve by ball milling, then place it in an atmosphere furnace and perform low-temperature oxidation at 370 °C for 1 h, then cool it with the furnace, then add it into 70 mL of hydrochloric acid solution with a molar concentration of 6 mol / L, stir and react for 3 h under the conditions of a temperature of 75 °C and a stirring rate of 400 r / min, then centrifuge, wash the precipitate 5 times with distilled water, and then place it in a vacuum drying oven and dry it for 4 h under the condition of a temperature of 75 °C to obtain acid-treated coal gangue powder;

[0053] Step S2: Place 10 g of acid-treated coal gangue powder in an atmosphere furnace, heat it to 750 °C at a heating rate of 5 °C / min and perform high-temperature calcination for 2 h, then cool it with the furnace, then add 13 g of sodium carbonate, and perform high-temperature calcination at 850 °C for 2 h, then cool it with the furnace to obtain calcined coal gangue powder;

[0054] Step S3: Add 10 g of calcined coal gangue powder into 130 mL of deionized water, then perform ultrasonic treatment for 60 min under the condition of an ultrasonic frequency of 45 kHz, then vacuum filter, add sodium aluminate and sodium hydroxide to the filtrate to adjust SiO2 The molar ratio with Al 2 O 3 is 2.0, and the molar ratio of Na 2 O to SiO 2 is 1.8. Then, it is stirred and reacted for 3 h under the conditions of a temperature of 65 °C and a stirring rate of 600 r / min. After that, it is placed in a hydrothermal reaction kettle and hydrothermally crystallized at 95 °C for 6 h to obtain coal gangue-based 4A zeolite;

[0055] Step S4: Add 2 g of coal gangue-based 4A zeolite, 3.5 g of ferrous sulfate heptahydrate, 2.2 mL of polyethylene glycol PEG-400, 50 mL of absolute ethanol, and 50 mL of deionized water into a three-necked flask equipped with a stirrer, a thermometer, a gas pipe, and a constant-pressure dropping funnel. Introduce nitrogen for protection and stir and react for 20 min under the conditions of a temperature of 30 °C and a stirring rate of 400 r / min. Then, while stirring, gradually add 60 mL of sodium borohydride solution with a molar concentration of 0.05 mol / L dropwise, control the dropping rate at 2 drops / s. After the dropping is completed, continue to stir and react for 2 h. After the reaction is completed, centrifuge the reaction product, wash the precipitate 5 times with distilled water, and then place it in a vacuum drying oven and dry it at 65 °C for 4 h to obtain zero-valent iron-loaded composite zeolite;

[0056] Step S5: Add 90 mL of absolute ethanol and 30 mL of deionized water into a three-necked flask equipped with a stirrer, a thermometer, and a gas pipe. Introduce nitrogen for protection and stir and react for 5 min under the conditions of a temperature of 30 °C and a stirring rate of 400 r / min. Then, adjust the pH to 9.5 with 27% ammonia water. After that, add 10 g of zero-valent iron-loaded composite zeolite and continue to stir and react at 85 °C for 30 min. Then, add 2.5 g of KH-560 silane coupling agent and continue to stir and react for 3 h. After the reaction is completed, centrifuge the reaction product, and place the precipitate in a vacuum drying oven and dry it at 65 °C for 3 h to obtain epoxy composite zeolite;

[0057] Step S6: Add 10 g of epoxy composite zeolite, 3.4 g of iminodiacetonitrile, and 100 mL of anhydrous tetrahydrofuran into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 15 min under the conditions of a temperature of 30 °C and a stirring rate of 400 r / min. Then, raise the temperature to 65 °C and continue to stir and react for 6 h. After the reaction is completed, cool the reaction product to room temperature, then centrifuge it, wash the precipitate 5 times with anhydrous acetone, and then place it in a vacuum drying oven and dry it at 65 °C for 2 h to obtain cyano composite zeolite;

[0058] Step S7: Add 10 g of cyano composite molecular sieve, 40 g of potassium hydroxide, 90 mL of absolute ethanol, and 90 mL of deionized water into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 15 min under the conditions of a temperature of 30 °C and a stirring rate of 400 r / min. Then, raise the temperature to 100 °C and continue to stir and react for 30 h. After the reaction is completed, cool the reaction product to room temperature, then pour it into a hydrochloric acid solution with a mass fraction of 25%. Then, let it stand for 5 h, and then centrifuge. Wash the precipitate 5 times with distilled water, and then place it in a vacuum drying oven and dry it at a temperature of 55 °C for 10 h to obtain a coal gangue-based 4A molecular sieve composite adsorbent material.

[0059] Comparative Example 1:

[0060] This comparative example is a preparation method of a coal gangue-based 4A molecular sieve composite adsorbent material, including the following steps:

[0061] Step S1: Pass 10 g of coal gangue powder through a 200-mesh sieve by ball milling, then place it in an atmosphere furnace, and carry out low-temperature oxidation at a temperature of 370 °C for 1 h. Then, cool it with the furnace. Then, add it to 70 mL of hydrochloric acid solution with a molar concentration of 6 mol / L, and stir and react for 3 h under the conditions of a temperature of 75 °C and a stirring rate of 400 r / min. Then, centrifuge. Wash the precipitate 5 times with distilled water, and then place it in a vacuum drying oven and dry it at a temperature of 75 °C for 4 h to obtain acid-treated coal gangue powder;

[0062] Step S2: Place 10 g of acid-treated coal gangue powder in an atmosphere furnace, and raise the temperature to 750 °C at a heating rate of 5 °C / min and carry out high-temperature calcination for 2 h. Then, cool it with the furnace. Then, add 13 g of sodium carbonate and carry out high-temperature calcination at 850 °C for 2 h. Then, cool it with the furnace to obtain calcined coal gangue powder;

[0063] Step S3: Add 10 g of calcined coal gangue powder to 130 mL of deionized water, then carry out ultrasonic treatment for 60 min under the condition of an ultrasonic frequency of 45 kHz. Then, carry out vacuum filtration. Add sodium aluminate and sodium hydroxide to the filtrate to adjust the molar ratio of SiO 2 to Al 2 O 3 to be 2.0, and the molar ratio of Na 2 O to SiO 2 to be 1.8. Then, stir and react for 3 h under the conditions of a temperature of 65 °C and a stirring rate of 600 r / min. Then, place it in a hydrothermal reaction kettle and carry out hydrothermal crystallization at 95 °C for 6 h to obtain a coal gangue-based 4A molecular sieve composite adsorbent material.

[0064] Comparative Example 2:

[0065] This comparative example is a preparation method of a coal gangue-based 4A molecular sieve composite adsorbent material, including the following steps:

[0066] Step S1: Grind 10 g of coal gangue powder through a 200-mesh sieve by ball milling, then place it in an atmosphere furnace, perform low-temperature oxidation at a temperature of 370 °C for 1 h, then cool it with the furnace, then add it to 70 mL of hydrochloric acid solution with a molar concentration of 6 mol / L, stir and react at a temperature of 75 °C and a stirring rate of 400 r / min for 3 h, then centrifuge, wash the precipitate 5 times with distilled water, and then place it in a vacuum drying oven and dry it at a temperature of 75 °C for 4 h to obtain acid-treated coal gangue powder;

[0067] Step S2: Place 10 g of acid-treated coal gangue powder in an atmosphere furnace, heat it to a high temperature of 750 °C at a heating rate of 5 °C / min and calcine for 2 h, then cool it with the furnace, then add 13 g of sodium carbonate, and calcine at 850 °C for 2 h, then cool it with the furnace to obtain calcined coal gangue powder;

[0068] Step S3: Add 10 g of calcined coal gangue powder to 130 mL of deionized water, then perform ultrasonic treatment for 60 min under the condition of an ultrasonic frequency of 45 kHz, then vacuum filter, add sodium aluminate and sodium hydroxide to the filtrate, adjust the molar ratio of SiO 2 to Al 2 O 3 to be 2.0, and the molar ratio of Na 2 O to SiO 2 to be 1.8, then stir and react at a temperature of 65 °C and a stirring rate of 600 r / min for 3 h, then place it in a hydrothermal reaction kettle and perform hydrothermal crystallization at 95 °C for 6 h to obtain coal gangue-based 4A molecular sieve;

[0069] Step S4: Add 2 g of coal gangue-based 4A molecular sieve, 3.5 g of ferrous sulfate heptahydrate, 2.2 mL of polyethylene glycol PEG-400, 50 mL of absolute ethanol, and 50 mL of deionized water to a three-necked flask equipped with a stirrer, thermometer, gas pipe, and constant-pressure dropping funnel, introduce nitrogen protection, stir and react at a temperature of 30 °C and a stirring rate of 400 r / min for 20 min, then dropwise add 60 mL of sodium borohydride solution with a molar concentration of 0.05 mol / L drop by drop while stirring, control the dropping rate to be 2 drops / s, continue to stir and react for 2 h after dropping, centrifuge the reaction product after the reaction, wash the precipitate 5 times with distilled water, and then place it in a vacuum drying oven and dry it at a temperature of 65 °C for 4 h to obtain a coal gangue-based 4A molecular sieve composite adsorbent material.

[0070] Comparative Example 3:

[0071] This comparative example is a preparation method of a coal gangue-based 4A molecular sieve composite adsorption material, including the following steps:

[0072] Step S1: 10 g of coal gangue powder is ball-milled and sieved through a 200-mesh sieve, then placed in an atmosphere furnace and low-temperature oxidized at a temperature of 370 °C for 1 h, then cooled with the furnace, then added to 70 mL of hydrochloric acid solution with a molar concentration of 6 mol / L, and stirred and reacted at a temperature of 75 °C and a stirring rate of 400 r / min for 3 h, then centrifuged, the precipitate is washed 5 times with distilled water, and then placed in a vacuum drying oven and dried at a temperature of 75 °C for 4 h to obtain acid-treated coal gangue powder;

[0073] Step S2: 10 g of acid-treated coal gangue powder is placed in an atmosphere furnace and heated to a high temperature of 750 °C at a heating rate of 5 °C / min and calcined for 2 h, then cooled with the furnace, then 13 g of sodium carbonate is added, and calcined at 850 °C for 2 h, then cooled with the furnace to obtain calcined coal gangue powder;

[0074] Step S3: 10 g of calcined coal gangue powder is added to 130 mL of deionized water, then ultrasonically treated at an ultrasonic frequency of 45 kHz for 60 min, then vacuum filtered, sodium aluminate and sodium hydroxide are added to the filtrate to adjust the molar ratio of SiO 2 to Al 2 O 3 to 2.0 and the molar ratio of Na 2 O to SiO 2 to 1.8, then stirred and reacted at a temperature of 65 °C and a stirring rate of 600 r / min for 3 h, then placed in a hydrothermal reaction kettle and hydrothermally crystallized at 95 °C for 6 h to obtain coal gangue-based 4A molecular sieve;

[0075] Step S4: 90 mL of absolute ethanol and 30 mL of deionized water are added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, nitrogen protection is introduced, and stirred and reacted at a temperature of 30 °C and a stirring rate of 400 r / min for 5 min, then adjusted to pH 9.5 with 27% ammonia water, then 10 g of coal gangue-based 4A molecular sieve is added and the temperature is raised to 85 °C and stirred and reacted for another 30 min, then 2.5 g of KH-560 silane coupling agent is added and stirred and reacted for 3 h. After the reaction is completed, the reaction product is centrifuged, and the precipitate is placed in a vacuum drying oven and dried at a temperature of 65 °C for 3 h to obtain epoxy composite molecular sieve;

[0076] Step S5: Add 10 g of epoxy composite molecular sieve, 3.4 g of iminodiacetonitrile, and 100 mL of anhydrous tetrahydrofuran into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 15 min under the conditions of a temperature of 30°C and a stirring rate of 400 r / min. Then, raise the temperature to 65°C and continue stirring and reacting for 6 h. After the reaction is completed, cool the reaction product to room temperature, then centrifuge, wash the precipitate with anhydrous acetone 5 times, and then place it in a vacuum drying oven and dry it at a temperature of 65°C for 2 h to obtain a cyano composite molecular sieve;

[0077] Step S6: Add 10 g of cyano composite molecular sieve, 40 g of potassium hydroxide, 90 mL of anhydrous ethanol, and 90 mL of deionized water into a three-necked flask equipped with a stirrer and a thermometer. Stir and react for 15 min under the conditions of a temperature of 30°C and a stirring rate of 400 r / min. Then, raise the temperature to 100°C and continue stirring and reacting for 30 h. After the reaction is completed, cool the reaction product to room temperature, then pour it into a hydrochloric acid solution with a mass fraction of 25%, then let it stand for 5 h, then centrifuge, wash the precipitate with distilled water 5 times, and then place it in a vacuum drying oven and dry it at a temperature of 55°C for 10 h to obtain a coal gangue-based 4A molecular sieve composite adsorption material.

[0078] Performance test:

[0079] Use CuSO 4 ·5H 2 0, MnSO 4 ·H 2 0 and deionized water to prepare copper sulfate solution and manganese sulfate solution with a concentration of 200 mg / L as simulated wastewater containing Cu 2+ and Mn 2+ ;

[0080] Add the coal gangue-based 4A molecular sieve composite adsorption materials of Examples 1-3 and Comparative Examples 1-3 into 50 mL of wastewater containing Cu 2+ and Mn 2+ at an addition amount of 1 g / L, then place it in a water bath constant temperature oscillator for oscillating adsorption for 12 h, then filter it with a 0.45 μm needle filter, and use a PerkinElmer PinAAcle 900 series atomic absorption spectrometer to measure the concentrations of Cu 2+ and Mn 2+ in the filtrate, and calculate their removal rate η. Among them, the calculation formula is:

[0081] η=(C 0 -C e ) / C 0 ×100%;

[0082] In the formula:

[0083] C 0 and C e are the mass concentrations of metal ions (Cu 2+ and Mn 2+ ) in the solution before and after adsorption, in mg / L.

[0084] The test results are shown in the following table:

[0085]

[0086] Referring to the data in the above table, by comparing Example 3 with Comparative Example 1, it can be known that loading nano-zero-valent iron and introducing a large number of carboxyl groups can significantly improve the heavy metal ion adsorption effect of the coal gangue-based 4A zeolite composite adsorbent material. By comparing Example 3 with Comparative Example 2, it can be known that introducing a large number of carboxyl groups can significantly improve the heavy metal ion adsorption effect of the coal gangue-based 4A zeolite composite adsorbent material. By comparing Example 3 with Comparative Example 3, it can be known that loading nano-zero-valent iron can significantly improve the heavy metal ion adsorption effect of the coal gangue-based 4A zeolite composite adsorbent material. Therefore, considering the three aspects together, it can be found that loading nano-zero-valent iron and introducing a large number of carboxyl groups can significantly improve the heavy metal ion adsorption ability. According to Examples 1-3, it can be known that the coal gangue-based 4A zeolite composite adsorbent material of the present application has excellent heavy metal ion adsorption effect.

[0087] In the description of this specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0088] The above content is only an example and explanation of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined by this application, they should all belong to the protection scope of the present invention.

Claims

1. A method for preparing a gangue-based 4A molecular sieve composite adsorption material, characterized in that: The following steps are involved: Step a1: stirring the gangue-based 4A molecular sieve, ferrous sulfate heptahydrate, polyethylene glycol, anhydrous ethanol and deionized water for reaction, then adding sodium borohydride solution dropwise while stirring, and continuing to stir the reaction after the addition is completed. After the reaction is completed, the reaction product is centrifuged, and the precipitate is washed and dried to obtain a zero-valent iron-loaded composite molecular sieve; Step a2: Anhydrous ethanol and deionized water are stirred for reaction, and then the pH is adjusted with ammonia water, and then the loaded zero-valent iron composite molecular sieve and KH-560 silane coupling agent are added and continued to stir and react. After the reaction is completed, the reaction product is centrifuged and the precipitate is dried to obtain the epoxy composite molecular sieve; Step a3: stirring the epoxy composite molecular sieve, iminodiacetonitrile and anhydrous tetrahydrofuran for reaction, cooling the reaction product after the reaction is completed, and then centrifuging it, washing and drying the precipitate to obtain the cyano composite molecular sieve; Step a4: Stir the cyano composite molecular sieve, potassium hydroxide, anhydrous ethanol and deionized water for reaction. After the reaction is completed, cool the reaction product and then pour it into a hydrochloric acid solution. Then, let it stand and centrifuge it, wash and dry the precipitate to obtain a coal gangue-based 4A molecular sieve composite adsorption material.

2. The method for preparing a gangue-based 4A molecular sieve composite adsorption material according to claim 1, characterized in that: The amount ratio of the gangue-based 4A molecular sieve, ferrous sulfate heptahydrate, polyethylene glycol, anhydrous ethanol, deionized water and sodium borohydride solution in step a1 is 2g: 3-3.5g: 2-2.2mL: 40-50mL: 40-50mL: 50-60mL; the polyethylene glycol is PEG-400; and the molar concentration of the sodium borohydride solution is 0.03-0.05mol / L.

3. The method for preparing a gangue-based 4A molecular sieve composite adsorption material according to claim 1, characterized in that: The dosage ratio of the anhydrous ethanol, deionized water, loaded zero-valent iron composite molecular sieve and KH-560 silane coupling agent in step a2 is 80-90 mL: 20-30 mL: 10 g: 0.5-2.5 g; the mass fraction of the ammonia water is 25-27%.

4. The method for preparing a gangue-based 4A molecular sieve composite adsorption material according to claim 1, characterized in that: The usage ratio of the epoxy composite molecular sieve, iminodiacetonitrile and anhydrous tetrahydrofuran in step a3 is 10g:1.8-3.4g:90-100mL.

5. The method for preparing a gangue-based 4A molecular sieve composite adsorption material according to claim 1, characterized in that: The usage ratio of the cyano composite molecular sieve, potassium hydroxide, anhydrous ethanol and deionized water in step a4 is 10g:35-40g:80-90mL:80-90mL; the mass fraction of the hydrochloric acid solution is 20-25%.

6. The method for preparing a gangue-based 4A molecular sieve composite adsorption material according to claim 1, characterized in that: The gangue-based 4A molecular sieve is prepared by the following steps: Step b1: ball-milling and sieving the gangue powder, then oxidizing it, then cooling it in the furnace and adding it to a hydrochloric acid solution, then stirring it for reaction, then centrifuging, washing and drying it to obtain acid-treated gangue powder; Step b2: calcining the acid-treated coal gangue powder, cooling it with the furnace, adding sodium carbonate to continue calcining, and then cooling it with the furnace to obtain calcined coal gangue powder; Step b3: Add calcined gangue powder to deionized water, then perform ultrasonic treatment, and then vacuum filter, add sodium aluminate and sodium hydroxide to the filtrate, adjust the molar ratio of SiO2 to Al2O3 to 2.0, and the molar ratio of Na2O to SiO2 to 1.8, then stir the reaction and hydrothermal crystallize to obtain gangue-based 4A molecular sieve.

7. The method for preparing a gangue-based 4A molecular sieve composite adsorption material according to claim 6, characterized in that: The main chemical components of the gangue powder in step b1 are: w(SiO2)=59.9%, w(Al2O3)=24.6%, w(Fe2O3)=4.7%, w(TiO2)=0.94%, w(CaO)=8.9%, w(MgO)=0.96% and w(others)=1.91%, and w(loss on ignition)=12.86%; The usage ratio of the coal gangue powder and the hydrochloric acid solution is 10g:60-70mL; the molar concentration of the hydrochloric acid solution is 6mol / L.

8. The method for preparing a gangue-based 4A molecular sieve composite adsorption material according to claim 6, characterized in that: The usage ratio of the acid-treated coal gangue powder and sodium carbonate in step b2 is 10g:12-13g.

9. The method for preparing a gangue-based 4A molecular sieve composite adsorption material according to claim 6, characterized in that: The usage ratio of the calcined coal gangue powder and deionized water in step b3 is 10g:120-130mL.

10. A gangue-based 4A molecular sieve composite adsorption material, characterized in that: The gangue-based 4A molecular sieve composite adsorption material is prepared by the preparation method of the gangue-based 4A molecular sieve composite adsorption material according to any one of claims 1 to 9.

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