Nucleation granulation seed crystal for fixing carbon dioxide as well as preparation method and application of nucleation granulation seed crystal

Abstract

The invention provides a nucleation granulation seed crystal for fixing carbon dioxide as well as a preparation method and application of the nucleation granulation seed crystal, and belongs to the technical field of environmental protection and water treatment. The seed crystal comprises a carrier material and alkaline active sites loaded on the carrier material; the materials of the alkaline active sites comprise one or more of alkali metal oxides and alkaline earth metal oxides. The seed crystal provided by the invention can be applied to a nucleation granulation process, alkaline active sites on the surface of the seed crystal can consume a large amount of hydrogen ions and accelerate the dissolution and hydrolysis process of gas carbon dioxide, so that the gas carbon dioxide is efficiently converted into carbonate, and then metal ions are induced to rapidly crystallize on the surface of the seed crystal in a carbonate precipitation form to form carbonate granules; therefore, mineralization fixation of carbon dioxide and efficient removal and granulation recovery of metal ions in wastewater are synchronously realized.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection and water treatment, and in particular relates to a nuclear crystal granulation seed for fixing carbon dioxide and a preparation method and application thereof. Background Art

[0002] Carbon neutrality, carbon fixation, and carbon dioxide mineralization are currently hot topics in the field of environmental protection. The large amount of carbon dioxide in industrial waste gas emitted into the atmosphere will cause global warming, while the emission of metal ions in industrial wastewater poses a serious threat to the ecological environment and human health. Therefore, the development of efficient carbon fixation 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 and oceans, but the carbon sequestration capacity of these natural carbon sinks is limited and is affected by many factors. Carbon dioxide mineralization technology converts carbon dioxide into stable carbonate minerals through chemical reactions, thereby achieving long-term and stable carbon sequestration. However, most current carbon dioxide mineralization technologies have problems such as high cost and low efficiency, which limits 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 accumulate through the food chain, ultimately endangering human health. Although traditional metal ion removal technologies such as chemical precipitation, ion exchange, and membrane separation can remove some metal ions, they often have problems such as high treatment costs and serious secondary pollution.

[0005] In summary, the existing carbon fixation technology and industrial wastewater treatment technology are both insufficient and difficult to meet environmental protection needs. Therefore, developing a new carbon fixation technology to achieve efficient and low-cost carbon dioxide mineralization and solve the problem of metal ion removal and recovery in industrial wastewater has become an urgent problem to be solved in the current environmental protection field. Summary of the invention

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

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a core crystal granulation seed for fixing carbon dioxide, the seed comprising a carrier material and alkaline active sites supported on the carrier material;

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

[0010] The crystal seeds provided by the present invention are designed and synthesized based on the principle of nuclear crystal granulation reaction. Nuclear crystal granulation is a new process for treating metal wastewater. This technology adds crystal seeds to water to induce metal ions to undergo heterogeneous crystallization reaction on the surface of the crystal seeds, thereby achieving the metal removal and recovery process. Existing finished crystal seeds, such as quartz sand, dolomite, garnet, etc., only play an inducing precipitation role as heterogeneous crystal nuclei in the process of nuclear crystal granulation to remove metals, and cannot simultaneously achieve efficient carbon dioxide mineralization.

[0011] The seed crystal provided by the present invention can be applied to the nuclear crystal granulation process to fix carbon dioxide and remove metal ions. During the nuclear crystal granulation reaction, the alkaline active sites on the surface of the seed crystal can consume a large number of hydrogen ions, accelerate the dissolution and hydrolysis of gaseous carbon dioxide, and efficiently convert it into carbonate ions, thereby inducing metal ions to rapidly crystallize on the surface of the seed crystal in the form of carbonate precipitation to form carbonate granulation bodies, thereby simultaneously achieving the mineralization fixation of carbon dioxide and the efficient removal and granulation recovery of metal ions in wastewater.

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

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

[0014] In some embodiments of the present invention, the support material includes one or more of alumina, molecular sieves, zeolites, activated carbon and mesoporous silica.

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

[0016] The mesh size of the seed crystals is kept within the above range to ensure that the seed crystals are in a stable fluidized state during the nuclear crystal granulation process, thereby improving the carbon dioxide conversion performance and metal removal efficiency of the seed crystals to meet the needs of experimental or production applications.

[0017] In a second aspect, the present invention provides a method for preparing the seed crystal according to the first aspect, the preparation method comprising the following steps:

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

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

[0020] In the present invention, the carrier material acts as the "skeleton" of the seed crystal, providing a porous structure for the loading of the alkaline sites; it interacts with the alkaline active site precursor, promotes the activation and conversion of the alkaline active site precursor to the alkaline site, thereby creating active sites with extremely high alkalinity on the surface of the carrier material.

[0021] The metal ions in the alkaline active site precursor can be embedded in the carrier lattice gap. The original oxygen vacancies in the carrier material act as natural "traps" to capture metal atoms and release electrons. Under the action of the electron induction effect, the released electrons preferentially flow to the adjacent lattice oxygen ions (O 2- ), which increases the density of its electron cloud, O 2- The electron-donating capacity is improved and the coordination ability of lattice oxygen is strengthened, which ultimately promotes the formation of active sites (such as K2O, Na2O, Rb2O, CaO, etc.) and produces super strong alkalinity.

[0022] In the present invention, the selection of carrier materials has a direct impact on the performance and application value of the seed crystals. For example, the physicochemical properties (specific surface area, pore size distribution, etc.) of the carrier materials directly affect the loading efficiency, dispersion, and number and distribution of the alkaline active sites.

[0023] In the present invention, the carrier material should have good physical and chemical stability, be able to withstand certain changes in pH, and avoid unnecessary chemical reactions or structural changes during the reaction; a carrier material with a high specific surface area helps to increase the loading amount of alkaline active sites, increase the contact opportunities between metal ions and carbon dioxide during the nucleus crystal granulation process, and improve the reaction efficiency; the carrier material should also have a certain mechanical strength to ensure that a stable and good fluidized state can be maintained during the nucleus crystal granulation process. In the present invention, the preferred carrier material includes one or more of alumina, molecular sieves, zeolites, activated carbon, and mesoporous silica, and these materials have the following advantages:

[0024] Alumina: It has excellent physical and chemical stability, thermal stability and mechanical strength. It has abundant hydroxyl groups on its surface, which can interact with alkaline guests and promote the formation of super-alkaline active sites.

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

[0026] Zeolite: It has a three-dimensional smooth pore structure, which provides abundant space for the dispersion and loading of alkaline active site precursors, and its specific surface area can reach hundreds of m 2 / g, the specific surface area of ​​the modified Y-type zeolite can be maintained at 550-650m 2 / g range;

[0027] Activated carbon: has a very high specific surface area, usually 500-1500m 2 / g, and some can even reach up to 2000m 2 / g, with abundant micropores, mesopores and macropores inside, and exhibits good chemical stability under high temperature and strong alkaline environment.

[0028] In some embodiments of the present invention, the alkaline active site precursor is one or more of a hydroxide of a metal element in the alkaline active site, a strong acid and a strong base salt, and preferably a nitrate of a metal element in the alkaline active site.

[0029] As a non-limiting example, the alkaline active site precursor in the present invention may 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 invention, the ratio of the molar amount of the metal element in the solution of the alkaline active site precursor to the mass of the support 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 invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0031] In the present invention, the ratio of alkaline active site precursor to carrier material can directly affect the quantity and distribution of the alkaline active sites on the carrier material surface. When the ratio of alkaline active site precursor is low, the alkaline active sites generated by the load are less, which may cause the efficiency of the seed in removing metal ions and mineralizing and fixing carbon dioxide to be low. As the ratio of alkaline active site precursor increases, the number of alkaline active sites in the seed also increases accordingly, until the seed reaches optimal performance. However, when the ratio of alkaline active site precursor is too high, the alkaline active sites on the carrier surface can be in an overloaded state, which increases the cost on the one hand, and may cause the carrier pores to be blocked on the other hand, and the specific surface area is reduced, which limits the contact of gas, liquid, and solid, and reduces the activity of the seed.

[0032] In some embodiments of the present invention, the concentration of the metal element in the solution of the alkaline 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 invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0033] In the present invention, when the alkaline active site precursor solution fully 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 alkaline active site precursor solution is too low, the alkaline active sites generated by the loading are relatively small, and the efficiency of the seed crystal in removing metal ions and mineralizing and fixing carbon dioxide is relatively low; if the concentration of the alkaline active site precursor solution is too high, there will be too many alkaline active sites in the seed crystal, which may cause the carrier pores to be blocked, reduce the activity of the seed crystal, and even cause the structure of the carrier material to collapse.

[0034] In some embodiments of the present invention, the mass volume ratio of the support material to the solution of the alkaline 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 invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0035] In some embodiments of the present invention, the mixing in step (1) is performed under stirring conditions.

[0036] In some embodiments of the present invention, the mixing temperature in step (1) is 40-50° C., for example, 40° C., 42° C., 43° C., 45° C., 46° C., 48° C. or 50° C. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

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

[0038] In some embodiments of the present invention, the drying temperature in step (1) is 60-80° C., for example, 60° C., 62° C., 65° C., 68° C., 70° C., 72° C., 75° C., 78° C. or 80° C. However, the present invention is not limited to the listed values, and other values ​​not listed within the range are also applicable.

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

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

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

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

[0043] In the present invention, the generation and distribution of alkaline active sites are related to the calcination temperature and time. If the calcination temperature is too low, the decomposition efficiency of the alkaline active site precursor may be low or even unable to be decomposed; if the calcination temperature is too high, the support material may be sintered and the pore structure may be destroyed. If the calcination time is too short, the decomposition of the alkaline active site precursor may be incomplete.

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

[0045] In some embodiments of the present invention, the preparation method further comprises the following steps: before the mixing in step (1), the carrier material is sequentially ground, sieved with a 60-80 mesh sieve, washed and dried.

[0046] In the present invention, there is no particular limitation on the cleaning and drying methods, and those skilled in the art can routinely select. As a non-limiting example, the carrier material can be thoroughly cleaned with deionized water or ethanol, and then placed in an oven and dried at a temperature of 80-100° C. for 4-6 hours to ensure that the carrier material is completely dry.

[0047] In some embodiments of the present invention, the preparation method further comprises the following steps: after the calcination in step (2), the seed crystals are cooled and screened again to remove possible impurities and particles that do not meet the requirements, so as to ensure that the size and performance of the seed crystals meet the requirements.

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

[0049] In the present invention, 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 invention has the following beneficial effects:

[0051] The crystal seeds provided by the present invention are designed and synthesized based on the principle of nuclear crystal granulation reaction, and can be applied to the nuclear crystal granulation process to fix carbon dioxide and remove metal ions. In the nuclear crystal granulation reaction process, the alkaline active sites on the surface of the crystal seeds can consume a large number of hydrogen ions, accelerate the dissolution and hydrolysis process of gaseous carbon dioxide, and efficiently convert it into carbonate ions, thereby inducing metal ions to rapidly crystallize on the surface of the crystal seeds in the form of carbonate precipitation to form carbonate granulation bodies, thereby simultaneously realizing the mineralization fixation of carbon dioxide and the efficient removal and granulation recovery of metal ions in wastewater, having significant environmental friendliness and resource recovery value, and having broad application prospects in the fields of wastewater treatment and carbon dioxide emission reduction. DETAILED DESCRIPTION

[0052] The technical solution of the present invention is further described below by means of specific implementation methods. It should be understood by those skilled in the art that the specific implementation methods are only used to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0053] Example 1

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

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

[0056] Choose coconut shell activated carbon with high specific surface area (strength 95%, specific surface area about 950m 2 / g) as a carrier material. First, grind and screen to obtain 60-80 mesh coconut shell activated carbon, wash it repeatedly three times with deionized water, and dry it in an oven at 80°C for 6h to constant weight; dissolve 5.06g KNO3 in 200mL deionized water to prepare a potassium nitrate solution with a concentration of 0.25mol / L; add 60g of pretreated coconut shell activated carbon carrier to the above potassium nitrate solution, stir continuously at 45°C for 4 hours to fully load potassium nitrate, and then dry it in an oven at 70°C for 32 hours to obtain coconut shell activated carbon loaded with potassium nitrate; then place it in a covered crucible, heat it to 700°C at a heating rate of 6°C / min under a nitrogen atmosphere, and keep it warm for 3 hours; after calcination, cool it naturally and screen it again to obtain 60-80 mesh nuclear crystal granulation seeds (named FC-ac).

[0057] Commercial seed garnet and the seed FC-ac provided in this embodiment were used to treat nickel-containing wastewater, respectively, to investigate the carbon fixation and metal ion removal capabilities of the seed, and the steps were as follows:

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

[0059] When ordinary seed garnet is added, the concentration of nickel ions in the effluent after treatment is 130 mg / L. The calculation shows that the removal rate of nickel ions is 35%. The turbidity of the effluent fluctuates in the range of 50-80 NTU. The crystallized product is light green. Analysis of the crystallized product shows that it is mainly composed of nickel carbonate.

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

[0061] It can be seen that the removal efficiency of nickel ions in wastewater by the seed crystal FC-ac provided in this embodiment is significantly higher than that of garnet. And because nickel ions are converted into nickel carbonate, the mineralization and fixation efficiency of carbon dioxide by the seed crystal FC-ac is also significantly higher than that of garnet.

[0062] Example 2

[0063] This embodiment provides a nucleation granulation seed, which includes a carrier 5A type molecular sieve and alkaline active sites K2O loaded on the carrier 5A type molecular sieve.

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

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

[0066] Commercial seed dolomite and the seed FC-MS provided in this example were used to treat manganese-containing wastewater, respectively, to investigate the carbon fixation and metal ion removal capabilities of the seed, and the steps were as follows:

[0067] Seed crystals were added into a nuclear crystal granulation reactor, the effective height of the reactor was 184 cm, the effective volume was 2.92 L, and the seed crystal filling height was 25% of the effective height of the nuclear crystal granulation reactor; manganese-containing wastewater was introduced into the nuclear crystal granulation reactor, the concentration of manganese ions in the wastewater was 400 mg / L, the inlet pH was 9.6, and the inlet flow rate was 35 L / h; carbon dioxide was introduced at the same time, and the flow rate was 80 mL / min; the hydraulic retention time of the wastewater in the reactor was 5 min, and the effluent water quality was detected 10 min after the start of effluent.

[0068] When ordinary seed dolomite is added, the concentration of manganese ions in the effluent after treatment is 276 mg / L. The calculation shows that the removal rate of manganese ions is 31%. The turbidity of the effluent fluctuates in the range of 70-90 NTU. The crystallized product is pink. Analysis of the crystallized product shows that it is mainly composed of manganese carbonate.

[0069] When the seed crystal FC-ms provided in this embodiment is added, the concentration of manganese ions in the effluent after treatment is 55 mg / L. The removal rate of manganese ions is calculated to be 86.25%, and the turbidity of the effluent is stably maintained below 28 NTU. The crystallized product is pink, and analysis of the crystallized 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 this embodiment is significantly higher than that of dolomite. And because 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 of dolomite.

[0071] Example 3

[0072] This embodiment provides a nucleus crystal granulation seed, which includes a carrier Y-type zeolite and alkaline active site CaO loaded on the carrier Y-type zeolite.

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

[0074] Select Y-type zeolite (20-40 mesh, specific surface area of ​​about 650m 2 / g) as a carrier material. First, grind and screen to obtain a 60-80 mesh Y-type zeolite, wash it repeatedly three times with anhydrous ethanol and deionized water respectively, and dry it in an oven at 90°C for 5h to constant weight; dissolve 13.13g Ca(NO3)2 in 200mL deionized water to prepare a calcium nitrate solution with a concentration of 0.4mol / L; add 80g of the pretreated Y-type zeolite to the above calcium nitrate solution, stir continuously at 50°C for 5 hours to fully load the calcium nitrate, and then dry it in an oven at 70°C for 30 hours to obtain a Y-type zeolite loaded with calcium nitrate; then place it in a covered crucible, heat it to 600°C at a heating rate of 7°C / min in a nitrogen atmosphere, and keep it warm for 3 hours; after calcination, cool it naturally, and screen it again to obtain a 60-80 mesh nucleus crystal granulation seed (named FC-zeo).

[0075] Commercial seed quartz sand and the seed FC-zeo provided in this embodiment were used to treat cobalt-containing wastewater, respectively, to investigate the carbon fixation and metal ion removal capabilities of the seed, and the steps were as follows:

[0076] Seed crystals were added into a nuclear crystal granulation reactor, the effective height of the reactor was 184 cm, the effective volume was 2.92 L, and the seed crystal filling height was 25% of the effective height of the nuclear crystal granulation reactor; cobalt-containing wastewater was introduced into the nuclear crystal granulation reactor, the concentration of cobalt ions in the wastewater was 300 mg / L, the inlet pH was 10, and the inlet flow rate was 35 L / h; carbon dioxide was introduced at the same time, and the flow rate was 70 mL / min; the hydraulic retention time of the wastewater in the reactor was 5 min, and the effluent water quality was detected 10 min after the start of effluent.

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

[0078] When the seed crystal FC-zeo provided in this embodiment is added, the concentration of cobalt ions in the effluent after treatment is 37 mg / L. The removal rate of cobalt ions is calculated to be 87.6%, and the turbidity of the effluent is stably maintained below 17 NTU. The crystalline product is light red, and analysis of the crystalline 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 this embodiment is significantly higher than that of quartz sand. And because the cobalt ions are converted into cobalt carbonate, the mineralization and fixation efficiency of carbon dioxide by the seed crystal FC-zeo is also significantly higher than that of quartz sand.

[0080] Example 4

[0081] This embodiment provides a nuclear crystal granulation seed, and the preparation method thereof is different from that of Embodiment 2 only in that the concentration of the potassium nitrate solution is 0.8 mol / L.

[0082] The carbon fixation and metal ion removal capabilities of the seed crystals provided in this embodiment were investigated using the same method as in Example 2. After the seed crystals provided in this embodiment were added, the concentration of manganese ions in the effluent was 142 mg / L, and the removal rate of manganese ions was calculated to be 64.5%, the effluent turbidity was stably maintained at about 42 NTU, the crystallized product was pink, and the crystallized product was found to be mainly composed of manganese carbonate.

[0083] Compared with Example 2, since the concentration of the potassium nitrate solution in this example is relatively high, the alkaline active sites on the surface of the carrier are overloaded, the carrier pores are blocked, and the activity of the seed crystals is reduced. Therefore, the efficiency of removing manganese ions and the mineralization and fixation efficiency of carbon dioxide by the seeds provided in this example are reduced.

[0084] The above description is only a specific embodiment of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to the embodiments described herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A carbon dioxide fixation core crystal granulation seed, characterized in that: The seed crystals include a support material and alkaline active sites supported on the support material; The material of the basic active site includes one or more of an alkali metal oxide and an alkaline earth metal oxide.

2. The seed crystal 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 comprises CaO.

3. The seed crystal according to claim 1 or 2, characterized in that The support material includes one or more of alumina, molecular sieve, zeolite, activated carbon and mesoporous silica; Preferably, the mesh size of the seed crystal is 60-80 mesh.

4. A method for preparing a seed crystal according to any one of claims 1 to 3, characterized in that: The preparation method comprises the following steps: (1) mixing a support material with a solution of an alkaline active site precursor so that the alkaline active site precursor is loaded on the support material, and drying to obtain a support material loaded with the alkaline active site precursor; (2) calcining the carrier material carrying the alkaline active site precursor in a protective atmosphere to decompose the alkaline active site precursor to form alkaline active sites, thereby obtaining the seed crystal.

5. The preparation method according to claim 4, characterized in that: The alkaline active site precursor is one or more of a hydroxide of a metal element in the alkaline active site, a strong acid and a strong base salt, and is preferably a nitrate of a metal element in the alkaline active site; Preferably, the ratio of the molar amount of the metal element in the solution of the alkaline active site precursor to the mass of the support material is 0.25-1.7 mmol / g; Preferably, the concentration of the metal element in the solution of the alkaline active site precursor is 0.1-0.5 mol / L; Preferably, the mass volume ratio of the support material to the solution of the alkaline active site precursor is 300-400 g / L.

6. The preparation method according to claim 4 or 5, characterized in that: The mixing in step (1) is carried out under stirring conditions; Preferably, the mixing temperature in step (1) is 40-50°C; Preferably, the mixing time in step (1) is 3-5h; Preferably, the drying temperature in step (1) is 60-80° C. and the drying time is 24-36 hours.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The calcination temperature in step (2) is 600-800°C; Preferably, the calcination time in step (2) is 2-4 hours; Preferably, the heating rate of the calcination in step (2) is 5-8°C / min.

8. The preparation method according to any one of claims 4 to 7, characterized in that: The preparation method further comprises the following steps: Before the mixing in step (1), the carrier material is ground, sieved with a 60-80 mesh sieve, washed and dried in sequence; And / or, after the calcination in step (2), the seed crystals are cooled and sieved.

9. Use of the seed crystal according to any one of claims 1 to 3 or the seed crystal prepared by the preparation method according to any one of claims 4 to 8 in fixing carbon dioxide and removing metal ions.

10. The use according to claim 9, 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.