Carbon dioxide fixing core crystal prilling seed, and preparation method and application thereof

Abstract

The application provides a seed crystal for carbon dioxide fixation, and a preparation method and application thereof, and belongs to the technical field of environmental protection and water treatment. The seed crystal comprises a carrier material and basic active sites loaded on the carrier material; and the material of the basic active sites comprises one or more of alkali metal oxides and alkaline earth metal oxides. The seed crystal provided by the application can be applied to a seed crystal granulation process, the basic active sites on the surface of the seed crystal can consume a large amount of hydrogen ions, accelerate the dissolution and hydrolysis process of gaseous carbon dioxide, convert the gaseous carbon dioxide into carbonate ions in a high-efficient manner, and then induce metal ions to crystallize on the surface of the seed crystal in the form of carbonate precipitation, so that carbonate granules are formed, and the mineralization and fixation of carbon dioxide and the high-efficient removal and granulation recovery of metal ions in wastewater are simultaneously achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of environmental protection and water treatment, and particularly relates to a core crystal granulation seed for fixing carbon dioxide and a preparation method and application thereof. BACKGROUND

[0002] Carbon neutralization, carbon sequestration and carbon dioxide mineralization are currently hot topics in the field of environmental protection. The emission of a large amount of carbon dioxide in industrial waste gas into the atmosphere will cause climate warming, and the emission of metal ions in industrial wastewater poses a serious threat to the ecological environment and human health. Therefore, developing efficient carbon sequestration technology and metal ion removal and recovery technology has become an urgent need in the field of environmental protection.

[0003] Traditional carbon sequestration technologies mostly rely on natural carbon sinks such as forests, oceans, etc., but the carbon sequestration capacity of these natural carbon sinks is limited and is affected by many factors. Carbon dioxide mineralization technology, on the other hand, converts carbon dioxide into stable carbonate minerals through chemical reactions, thereby achieving long-term stable carbon sequestration. However, most current carbon dioxide mineralization technologies have problems such as high cost and low efficiency, which limit their widespread application.

[0004] At the same time, industrial wastewater contains a large amount of metal ions such as calcium, manganese, lead, nickel, cobalt, etc. These metal ions not only pose a threat to aquatic ecosystems, but also can be enriched through the food chain, ultimately endangering human health. Traditional metal ion removal technologies such as chemical precipitation, ion exchange, membrane separation, etc. can remove some metal ions, but often have problems such as high treatment cost and serious secondary pollution.

[0005] In summary, existing carbon sequestration technologies and industrial wastewater treatment technologies have shortcomings and cannot meet environmental protection needs. Therefore, developing a new type of carbon sequestration technology to achieve efficient and low-cost carbon dioxide mineralization and simultaneously solving the problems of metal ion removal and recovery in industrial wastewater has become a pressing problem in the field of environmental protection. SUMMARY

[0006] In view of the shortcomings of the prior art, the present application aims to provide a core crystal granulation seed for fixing carbon dioxide and a preparation method and application thereof. The core crystal granulation seed can simultaneously achieve carbon dioxide mineralization and fixation, and efficient removal and granulation recovery of metal ions in wastewater.

[0007] To achieve this purpose, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a core crystal granulation seed for fixing carbon dioxide, which comprises a carrier material and alkaline active sites loaded on the carrier material.

[0009] The material of the basic active site includes one or more of alkali metal oxides and alkaline earth metal oxides.

[0010] The seed crystal provided by the present application is designed and synthesized based on the principle of core crystal granulation reaction. Core crystal granulation is a new process for treating metal wastewater. The technology induces heterogeneous crystallization reaction of metal ions on the surface of the seed crystal by adding seed crystal in water, to realize the removal and recovery of metals. The existing finished seed crystal, such as quartz sand, dolomite, and garnet, only plays an inducing precipitation role as a heterogeneous crystal nucleus in the process of removing metals by core crystal granulation, and cannot simultaneously realize efficient carbon dioxide mineralization.

[0011] The seed crystal provided by the present application can be applied to the core crystal granulation process to fix carbon dioxide and remove metal ions. In the core crystal granulation reaction process, the basic active points on the surface of the seed crystal can consume a large number of hydrogen ions, accelerate the dissolution and hydrolysis process of gaseous carbon dioxide, and convert it into carbonate, and then induce metal ions to crystallize on the surface of the seed crystal in the form of carbonate precipitation to form carbonate granules, thereby simultaneously realizing the mineralization and fixation of carbon dioxide and the efficient removal and granulation recovery of metal ions in wastewater.

[0012] In some embodiments of the present application, the alkali metal oxide includes one or more of Na2O, K2O, and Rb2O.

[0013] In some embodiments of the present application, the alkaline earth metal oxide includes CaO.

[0014] In some embodiments of the present application, the carrier material includes one or more of alumina, molecular sieve, zeolite, activated carbon, and mesoporous silica.

[0015] In some embodiments of the present application, the mesh number of the seed crystal is 60-80 mesh.

[0016] The mesh number of the seed crystal is kept in the above range to ensure that the seed crystal presents a stable fluidized state in the core crystal granulation process, thereby improving the carbon dioxide conversion performance of the seed crystal and the removal efficiency of metals to meet the needs of experimental or production applications.

[0017] In a second aspect, the present application provides a preparation method of the seed crystal according to the first aspect, and the preparation method includes the following steps:

[0018] (1) mixing a carrier material with a solution of a basic active site precursor, so that the basic active site precursor is loaded on the carrier material, and drying to obtain a carrier material loaded with a basic active site precursor;

[0019] (2) calcining the carrier material loaded with the basic active site precursor in a protective atmosphere to decompose the basic active site precursor to form basic active sites, thereby obtaining the seed crystal.

[0020] In the present application, the carrier material acts as the "skeleton" of the seed crystal, providing a pore structure for the loading of basic sites; and interacts with the basic active site precursor to promote the activation and conversion of the basic active site precursor to basic sites, thereby creating active sites with extremely high basicity on the surface of the carrier material.

[0021] The metal ions in the basic active site precursor can be embedded in the interstitial gaps of the carrier lattice, and the original oxygen vacancies of the carrier material act as natural "traps" to capture metal atoms and release electrons. Under the action of the electron-induced effect, the released electrons preferentially flow to the adjacent lattice oxygen ions (O 2- ), increasing the electron cloud density of the O 2- , improving the electron-donating ability and coordination ability of the lattice oxygen, and ultimately promoting the formation of active sites (such as K2O, Na2O, Rb2O, CaO, etc.) and generating super strong basicity.

[0022] In the present application, the selection of the carrier material has a direct impact on the performance and application value of the seed crystal. For example, the physical and chemical properties of the carrier material (such as specific surface area and pore size distribution) directly affect the loading efficiency, dispersion, and number and distribution of the basic active sites.

[0023] In the present application, the carrier material should have good physical and chemical stability, be able to withstand certain changes in acidity and alkalinity, and avoid unnecessary chemical reactions or structural changes during the reaction process; carrier materials with high specific surface area can help increase the loading capacity of the basic active sites, increase the contact opportunities between metal ions and carbon dioxide during the nucleation and granulation process, and improve the reaction efficiency; the carrier material should also have a certain mechanical strength to ensure that it can maintain a stable and good fluidized state during the nucleation and granulation process. In the present application, the preferred carrier material includes one or more of alumina, molecular sieve, zeolite, activated carbon, and mesoporous silica, which have the following advantages:

[0024] Alumina: has excellent physical and chemical stability, thermal stability, and mechanical strength, and has a rich surface of hydroxyl groups that can interact with the basic guest to promote the generation of super strong basic active sites;

[0025] Molecular sieve: has a large specific surface area, typically between 300-1000 m 2 / g, has a regular pore structure, and has good thermal and chemical stability;

[0026] Zeolite: has a three-dimensional open channel structure, provides abundant space for the dispersion and loading of the precursor of the basic active site, and the specific surface area can reach hundreds of m 2 / g, and the specific surface area of the modified Y-type zeolite can be maintained in the range of 550-650 m 2 / g.

[0027] Activated carbon: has a very high specific surface area, usually between 500-1500 m 2 / g, and even up to 2000 m 2 / g, and has abundant microporous, mesoporous and macroporous structures inside, and shows good chemical stability at high temperature and strong alkali environment.

[0028] In some embodiments of the present application, the precursor of the basic active site is one or more of the hydroxides of the metal elements in the basic active site, strong acid and strong base salts, and preferably nitrates of the metal elements in the basic active site.

[0029] As a non-limiting example, the precursor of the basic active site in the present application can include one or more of potassium nitrate, potassium fluoride, potassium hydroxide, sodium nitrate, calcium nitrate and rubidium nitrate.

[0030] In some embodiments of the present application, the ratio of the molar amount of the metal elements in the solution of the precursor of the basic active site to the mass of the carrier material is 0.25-1.7 mmol / g; for example, it can be 0.25 mmol / g, 0.3 mmol / g, 0.4 mmol / g, 0.5 mmol / g, 0.6 mmol / g, 0.7 mmol / g, 0.8 mmol / g, 0.9 mmol / g, 1 mmol / g, 1.2 mmol / g, 1.3 mmol / g, 1.5 mmol / g, 1.6 mmol / g or 1.7 mmol / g, etc. However, the present application is not limited to the listed values, and other unlisted values within this range are also applicable.

[0031] In the present application, the ratio of the precursor of the basic active site to the carrier material directly affects the number and distribution of the basic active sites loaded on the surface of the carrier material. When the ratio of the precursor of the basic active site is low, the generated basic active sites are less, which can result in a lower efficiency of the seed crystal in removing metal ions and mineralizing carbon dioxide. As the ratio of the precursor of the basic active site increases, the number of basic active sites in the seed crystal also increases accordingly until the seed crystal reaches the optimal performance. However, when the ratio of the precursor of the basic active site is too high, the basic active sites on the surface of the carrier will be in an overloading state, which on the one hand increases the cost, and on the other hand can cause the carrier pores to be blocked, the specific surface area to decrease, and the contact of gas, liquid and solid to be limited, thereby reducing the activity of the seed crystal.

[0032] In some embodiments of the present application, the concentration of the metal element in the solution of the basic active site precursor is 0.1-0.5 mol / L; for example, it can be 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L or 0.5 mol / L, etc. However, the present application is not limited to the listed values, and other unlisted values within the range are also applicable.

[0033] In the present application, when the basic active site precursor solution sufficiently infiltrates the carrier material, the concentration of the solution is directly related to the loading amount of the carrier material. If the concentration of the basic active site precursor solution is too low, the generated basic active sites are less, and the efficiency of the seed to remove metal ions and mineralize carbon dioxide is low. If the concentration of the basic active site precursor solution is too high, the basic active sites in the seed are too much, which can cause the carrier pore to be blocked, the activity of the seed to be reduced, and even the structure of the carrier material to collapse.

[0034] In some embodiments of the present application, the mass-to-volume ratio of the carrier material to the solution of the basic active site precursor is 300-400 g / L; for example, it can be 300 g / L, 310 g / L, 320 g / L, 330 g / L, 340 g / L, 350 g / L, 360 g / L, 370 g / L, 380 g / L, 390 g / L or 400 g / L, etc. However, the present application is not limited to the listed values, and other unlisted values within the range are also applicable.

[0035] In some embodiments of the present application, the mixing in step (1) is carried out under stirring.

[0036] In some embodiments of the present application, the temperature of the mixing in step (1) is 40-50℃; for example, it can be 40℃, 42℃, 43℃, 45℃, 46℃, 48℃ or 50℃, etc. However, the present application is not limited to the listed values, and other unlisted values within the range are also applicable.

[0037] In some embodiments of the present application, the mixing time in step (1) is 3-5 h; for example, it can be 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 4.8 h or 5 h, etc. However, the present application is not limited to the listed values, and other unlisted values within the range are also applicable.

[0038] In some embodiments of the present application, the temperature of the drying in step (1) is 60-80℃, for example, it can be 60℃, 62℃, 65℃, 68℃, 70℃, 72℃, 75℃, 78℃ or 80℃, etc. However, the present application is not limited to the listed values, and other values not listed in this range are also applicable.

[0039] In some embodiments of the present application, the time of the drying in step (1) is 24-36h; for example, it can be 24h, 26h, 28h, 30h, 32h, 34h or 36h, etc. However, the present application is not limited to the listed values, and other values not listed in this range are also applicable.

[0040] In the present application, the role of calcination is to decompose the basic active site precursor, thereby forming basic active sites on the carrier material. Those skilled in the art can select appropriate calcination conditions according to the types of basic active site precursor and carrier material.

[0041] As a non-limiting example in the present application, the temperature of the calcination in step (2) is 600-800℃; for example, it can be 600℃, 620℃, 630℃, 650℃, 660℃, 680℃, 700℃, 720℃, 730℃, 750℃, 760℃, 780℃ or 800℃, etc. However, the present application is not limited to the listed values, and other values not listed in this range are also applicable.

[0042] As a non-limiting example in the present application, the time of the calcination in step (2) is 2-4h; for example, it can be 2h, 2.2h, 2.5h, 2.8h, 3h, 3.2h, 3.5h, 3.8h or 4h, etc. However, the present application is not limited to the listed values, and other values not listed in this range are also applicable.

[0043] In the present application, the generation and distribution of basic active sites are related to the calcination temperature and time. If the calcination temperature is too low, it may lead to low decomposition efficiency of the basic active site precursor, or even unable to decompose. If the calcination temperature is too high, it may lead to sintering of the carrier material and destruction of the pore structure. If the calcination time is too short, it may lead to incomplete decomposition of the basic active site precursor.

[0044] In some embodiments of the present application, the heating rate of the calcination in step (2) is 5-8℃ / min; for example, it can be 5℃ / min, 5.5℃ / min, 6℃ / min, 6.5℃ / min, 7℃ / min, 7.5℃ / min or 8℃ / min, etc. However, the present application is not limited to the listed values, and other values not listed in this range are also applicable.

[0045] In some embodiments of the present application, the preparation method further comprises the following steps: before the mixing in step (1), sequentially grinding, 60-80 mesh sieving, washing and drying the carrier material.

[0046] In the present application, the method of washing and drying is not particularly limited and can be routinely selected by those skilled in the art. As a non-limiting example, the carrier material can be thoroughly washed with deionized water or ethanol and then dried in an oven at a temperature of 80-100℃ for 4-6 hours to ensure that the carrier material is completely dry.

[0047] In some embodiments of the present application, the preparation method further comprises the following steps: after the calcination in step (2), cooling and re-sieving the seed crystals. This is to remove possible impurities and substandard particles to ensure that the size and performance of the seed crystals meet the requirements.

[0048] In a third aspect, the present application provides a seed crystal as described in the first aspect or prepared by the preparation method of the second aspect for use in fixing carbon dioxide and removing metal ions.

[0049] In the present application, the metal ions are metal ions that can react with carbonate to form carbonate precipitates, including but not limited to one or more of calcium ions, zinc ions, manganese ions, lead ions, cadmium ions, nickel ions and cobalt ions.

[0050] Compared with the prior art, the present application has the following beneficial effects:

[0051] The seed crystal provided by the present application is designed and synthesized based on the principle of core crystal granulation reaction and can be applied in the core crystal granulation process to fix carbon dioxide and remove metal ions. In the core crystal granulation reaction process, the basic active sites on the surface of the seed crystal can consume a large number of hydrogen ions, accelerate the dissolution and hydrolysis process of the gas carbon dioxide, convert it into carbonate, and then induce the rapid crystallization of metal ions in the form of carbonate precipitates on the surface of the seed crystal, forming carbonate granules, thereby simultaneously achieving the mineralization and fixation of carbon dioxide and the efficient removal and granulation recovery of metal ions in wastewater, having significant environmental friendliness and resource recycling value, and having a wide application prospect in the fields of wastewater treatment and carbon dioxide emission reduction. DETAILED DESCRIPTION

[0052] The technical solutions of the present application are further illustrated by the specific embodiments below. Those skilled in the art should understand that the specific embodiments are only to help understand the present application and should not be regarded as a specific limitation of the present application.

[0053] Example 1

[0054] The embodiment provides a core crystal granulation seed, which comprises a carrier coconut shell activated carbon and basic active sites K2O loaded on the carrier coconut shell activated carbon.

[0055] In the embodiment, the preparation method of the core crystal granulation seed is as follows:

[0056] Coconut shell activated carbon with high specific surface area (strength 95%, specific surface area about 950 m 2 / g) is selected as a carrier material. First, grinding and screening treatment is performed to obtain coconut shell activated carbon with a mesh size of 60-80, which is repeatedly cleaned with deionized water for three times and dried in an oven at 80 DEG C for 6 hours to constant weight; 5.06 g of KNO3 is dissolved in 200 mL of deionized water to prepare a potassium nitrate solution with a concentration of 0.25 mol / L; 60 g of the pretreated coconut shell activated carbon carrier is added into the potassium nitrate solution, and stirring is continuously performed at 45 DEG C for 4 hours to allow the potassium nitrate to be fully loaded, and then the potassium nitrate loaded coconut shell activated carbon is dried in an oven at 70 DEG C for 32 hours; then the potassium nitrate loaded coconut shell activated carbon is placed in a covered crucible and heated to 700 DEG C at a heating rate of 6 DEG C / min under a nitrogen atmosphere, and kept for 3 hours; after calcination, the potassium nitrate loaded coconut shell activated carbon is naturally cooled, and screening is performed again to obtain core crystal granulation seeds with a mesh size of 60-80 (named as FC-ac).

[0057] The nickel-containing wastewater is treated by using the commercial seed garnet and the seed FC-ac provided in the embodiment respectively, and the carbon fixation and metal ion removal capacity of the seed is investigated, and the steps are as follows:

[0058] The seed is added into a core crystal granulation reactor, the effective height of the reactor is 184 cm, the effective volume is 2.92 L, and the seed filling height is 25% of the effective height of the core crystal granulation reactor; the nickel-containing wastewater is introduced into the core crystal granulation reactor, the concentration of nickel ions in the wastewater is 200 mg / L, the influent pH is 9, and the influent flow rate is 35 L / h; at the same time, carbon dioxide is introduced, and the flow rate is 60 mL / min; the hydraulic retention time of the wastewater in the reactor is 5 min, and the effluent quality is detected after 10 min of effluent.

[0059] When the commercial seed garnet is added, the concentration of nickel ions in the effluent after treatment is 130 mg / L, and the removal rate of nickel ions is calculated to be 35%; the effluent turbidity fluctuates in the range of 50-80 NTU; the crystallization product is light green; and analysis of the crystallization product shows that the crystallization product is mainly composed of nickel carbonate.

[0060] When the seed FC-ac provided in the embodiment is added, the concentration of nickel ions in the effluent after treatment is 30 mg / L, and the removal rate of nickel ions is calculated to be 85%; the effluent turbidity is stably maintained below 20 NTU; the crystallization product is light green; and analysis of the crystallization product shows that the crystallization product is mainly composed of nickel carbonate.

[0061] Therefore, the seed crystal FC-ac provided in the embodiment has a significantly higher removal efficiency of nickel ions in wastewater than the garnet. Moreover, since the nickel ions are converted into nickel carbonate, the seed crystal FC-ac has a significantly higher carbon dioxide mineralization and fixation efficiency than the garnet.

[0062] Example 2

[0063] The present embodiment provides a core crystal prilling seed, which comprises a carrier 5A molecular sieve and K2O basic active sites loaded on the carrier 5A molecular sieve.

[0064] In the present embodiment, the preparation method of the core crystal prilling seed is as follows:

[0065] 5A molecular sieve (spherical, specific surface area of about 900 m 2 / g) is selected as the carrier material. First, grinding and screening treatment is performed to obtain 60-80 mesh molecular sieve, which is repeatedly washed three times with deionized water and dried in an oven at 100°C for 4h to constant weight; 6.07g of KNO3 is dissolved in 200mL of deionized water to prepare a 0.3mol / L potassium nitrate solution; 70g of the pretreated molecular sieve carrier is added to the above potassium nitrate solution, continuously stirred at 40°C for 5 hours to allow the potassium nitrate to be fully loaded, and then dried in an oven at 80°C for 24 hours to obtain a potassium nitrate-loaded molecular sieve; then it is placed in a covered crucible and heated to 600°C at a heating rate of 8°C / min under a nitrogen atmosphere, and kept for 2 hours; after calcination is completed, it is naturally cooled, and screening is performed again to obtain 60-80 mesh core crystal prilling seed (named FC-ms).

[0066] Commercial seed dolomite and the seed crystal FC-ms provided in the present embodiment are used to treat manganese-containing wastewater respectively to investigate the carbon fixation and metal ion removal capacity of the seed crystal, and the steps are as follows:

[0067] The seed crystal is added to the core crystal prilling reactor, the effective height of the reactor is 184cm, the effective volume is 2.92L, and the seed crystal filling height is 25% of the effective height of the core crystal prilling reactor; the manganese-containing wastewater is introduced into the core crystal prilling reactor, the concentration of manganese ions in the wastewater is 400mg / L, the influent pH is 9.6, and the influent flow rate is 35L / h; at the same time, carbon dioxide is introduced, and the flow rate is 80mL / min; the hydraulic retention time of the wastewater in the reactor is 5min, and the effluent quality is detected after 10min of effluent.

[0068] When the ordinary seed crystal dolomite is added, the concentration of manganese ions in the effluent after treatment is 276mg / L, and the removal rate of manganese ions is calculated to be 31%; the effluent turbidity fluctuates in the range of 70-90NTU; the crystallization product is pink; and analysis of the crystallization product shows that it is mainly composed of manganese carbonate.

[0069] When the seed crystal FC-ms provided in the embodiment is added, the concentration of manganese ions in the effluent after treatment is 55 mg / L, and the removal rate of manganese ions is calculated to be 86.25%. The effluent turbidity is stably maintained below 28 NTU, and the crystalline product is pink. Analysis of the crystalline product shows that it is mainly composed of manganese carbonate.

[0070] It can be seen that the removal efficiency of manganese ions in wastewater by the seed crystal FC-ms provided in the embodiment is significantly higher than that by dolomite. Since the manganese ions are converted into manganese carbonate, the mineralization and fixation efficiency of carbon dioxide by the seed crystal FC-ms is also significantly higher than that by dolomite.

[0071] Example 3

[0072] The present embodiment provides a core crystal granulation seed, which comprises a carrier Y zeolite and a basic active site CaO loaded on the carrier Y zeolite.

[0073] In the present embodiment, the preparation method of the core crystal granulation seed is as follows:

[0074] Y zeolite (20-40 mesh, specific surface area about 650 m 2 / g) is selected as the carrier material. First, grinding and screening treatment is performed to obtain Y zeolite of 60-80 mesh, which is repeatedly washed with anhydrous ethanol and deionized water for three times, and dried in an oven at 90°C for 5h to constant weight. 13.13g of Ca(NO3)2 is dissolved in 200mL of deionized water to prepare a calcium nitrate solution with a concentration of 0.4mol / L. 80g of pretreated Y zeolite is added to the above calcium nitrate solution, and stirred at 50°C for 5 hours to allow the calcium nitrate to be fully loaded, and then dried in an oven at 70°C for 30 hours to obtain Y zeolite loaded with calcium nitrate. Then, it is placed in a covered crucible and heated to 600°C at a heating rate of 7°C / min under a nitrogen atmosphere, and kept for 3 hours. After calcination, it is naturally cooled, and screened again to obtain core crystal granulation seed of 60-80 mesh (named FC-zeo).

[0075] Commercial seed quartz sand and the seed crystal FC-zeo provided in the present embodiment are used to treat cobalt-containing wastewater respectively to investigate the carbon fixation and metal ion removal capacity of the seed crystal. The steps are as follows:

[0076] The seed crystal is added into the core crystal prilling reactor, the effective height of the reactor is 184 cm, the effective volume is 2.92 L, and the seed crystal filling height is 25% of the effective height of the core crystal prilling reactor; the wastewater containing cobalt is introduced into the core crystal prilling reactor, the concentration of cobalt ions in the wastewater is 300 mg / L, the pH of the inlet water is 10, and the inlet water flow is 35 L / h; at the same time, carbon dioxide is introduced, and the flow is 70 mL / min; the hydraulic retention time of the wastewater in the reactor is 5 min, and the water quality is detected after 10 min of water outlet.

[0077] When the ordinary seed crystal quartz sand is added, after treatment, the concentration of cobalt ions in the effluent is 215 mg / L, and the removal rate of cobalt ions is calculated to be 28.3%; the effluent turbidity fluctuates in the range of 60-90 NTU; the crystallization product is light red; and analysis of the crystallization product shows that it is mainly composed of cobalt carbonate.

[0078] When the seed crystal FC-zeo provided in the embodiment is added, after treatment, the concentration of cobalt ions in the effluent is 37 mg / L, and the removal rate of cobalt ions is calculated to be 87.6%; the effluent turbidity is stably maintained below 17 NTU; the crystallization product is light red; and analysis of the crystallization product shows that it is mainly composed of cobalt carbonate.

[0079] It can be seen that the removal efficiency of cobalt ions in wastewater by the seed crystal FC-zeo provided in the embodiment is significantly higher than that of quartz sand. And since the cobalt ions are converted into cobalt carbonate, the carbon dioxide mineralization and fixation efficiency of the seed crystal FC-zeo is also significantly higher than that of quartz sand.

[0080] Example 4

[0081] The seed crystal provided in the embodiment is prepared by the method of Example 2, and the difference is that the concentration of the potassium nitrate solution is 0.8 mol / L.

[0082] The same method as in Example 2 is used to investigate the carbon fixation and metal ion removal capacity of the seed crystal provided in the embodiment. After treatment with the seed crystal provided in the embodiment, the concentration of manganese ions in the effluent is 142 mg / L, and the removal rate of manganese ions is calculated to be 64.5%; the effluent turbidity is stably maintained at about 42 NTU; the crystallization product is pink; and analysis of the crystallization product shows that it is mainly composed of manganese carbonate.

[0083] Compared with Example 2, due to the higher concentration of the potassium nitrate solution in the embodiment, the basic active sites on the surface of the carrier are excessively loaded, the carrier pores are blocked, and the activity of the seed crystal is reduced, so the removal efficiency of manganese ions and the mineralization and fixation efficiency of carbon dioxide of the seed crystal provided in the embodiment decrease.

[0084] The foregoing is merely illustrative of the various implementations of the present disclosure and the general principles thereof. Numerous modifications can be made to these illustrations, and equivalents can be substituted therefor, without departing from the scope of the present disclosure. The specific embodiments commensurate with the specific application are intended to be illustrative only and not limiting of the scope of the application as set forth in the following claims.

Claims

1. An application of a nucleus crystal granulation seed, characterized in that, The seed crystal is used to fix carbon dioxide and remove metal ions, and the seed crystal includes a carrier material and basic active sites loaded on the carrier material; The materials for the basic active sites include one or more of alkali metal oxides and alkaline earth metal oxides; The carrier material includes one or more of alumina, molecular sieve, zeolite, activated carbon, and mesoporous silica.

2. The application according to claim 1, characterized in that, The alkali metal oxide includes one or more of Na₂O, K₂O, and Rb₂O; And / or, the alkaline earth metal oxide includes CaO.

3. The application according to claim 1 or 2, characterized in that, The seed crystals have a mesh size of 60-80.

4. The application according to claim 1, characterized in that, The method for preparing the seed crystals includes the following steps: (1) Mix the carrier material with a solution of the basic active site precursor, so that the basic active site precursor is loaded on the carrier material, and dry it to obtain the carrier material loaded with the basic active site precursor; (2) The carrier material loaded with the basic active site precursor is calcined in a protective atmosphere to decompose the basic active site precursor to form basic active sites, thereby obtaining the seed crystal.

5. The application according to claim 4, characterized in that, The precursor of the basic active site is one or more of the following: hydroxide of the metal element in the basic active site, strong acid and strong base salt.

6. The application according to claim 5, characterized in that, The precursor of the basic active site is the nitrate of the metal element in the basic active site.

7. The application according to claim 4, characterized in that, The molar ratio of the metal element in the solution of the basic active site precursor to the mass of the carrier material is 0.25-1.7 mmol / g.

8. The application according to claim 4, characterized in that, The concentration of the metal element in the solution of the basic active site precursor is 0.1-0.5 mol / L.

9. The application according to claim 4, 7 or 8, characterized in that, The mass-to-volume ratio of the carrier material to the solution of the basic active site precursor is 300-400 g / L.

10. The application according to claim 4, characterized in that, The mixing described in step (1) is carried out under stirring conditions.

11. The application according to claim 4, characterized in that, The mixing temperature in step (1) is 40-50 ℃.

12. The application according to claim 4, characterized in that, The mixing time in step (1) is 3-5 h.

13. The application according to claim 4, characterized in that, The drying temperature in step (1) is 60-80 ℃ and the time is 24-36 h.

14. The application according to claim 4, characterized in that, The calcination temperature in step (2) is 600-800℃.

15. The application according to claim 4, characterized in that, The calcination time in step (2) is 2-4 h.

16. The application according to claim 4, characterized in that, The heating rate for calcination in step (2) is 5-8℃ / min.

17. The application according to claim 4, characterized in that, The preparation method further includes the following steps: Before mixing in step (1), the carrier material is ground, sieved through a 60-80 mesh sieve, washed and dried in sequence; And / or, after the calcination described in step (2), the seed crystals are cooled and sieved.

18. The application according to claim 1, characterized in that, The metal ions include one or more of calcium ions, zinc ions, manganese ions, lead ions, cadmium ions, nickel ions, and cobalt ions.