Urease-carbonic anhydrase concerted catalysis carbon sequestration method
Through the carbon sequestration method catalyzed by urease-carbonic anhydrase, combined with the use of humic acid, the problems of low carbon sequestration efficiency and poor stability in the prior art are solved, and efficient and stable carbon storage is achieved.
Patent Information
- Application Number
- CN202510278689.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-10
- Publication Date
- 2025-06-10
AI Technical Summary
The existing enzymatic mineralization technology is not very effective in carbon sequestration in farmland, and the enzyme catalytic process is greatly affected by environmental factors, resulting in low carbon sequestration efficiency.
The carbon sequestration method is adopted by the urease-carbonic anhydrase-coalic anhydrase synergistically catalyzed by adding urea, urease and carbonic anhydrase to the calcium source solution to generate calcium carbonate precipitation, and urease is used to catalyze the hydrolysis of urea to produce ammonia and carbon dioxide. The carbonic anhydrase accelerates the equilibrium reaction between carbon dioxide and water, promotes the formation of calcium carbonate, and improves the stability of calcium carbonate by adding humic acid.
The carbon sequestration efficiency is significantly improved, the formation rate of calcium carbonate precipitation is enhanced, and the long-term stability of carbon storage is improved through the addition of humic acid.
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Figure CN120114976A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of carbon sequestration, and particularly to a carbon sequestration method co-catalyzed by urease and carbonic anhydrase. Background Art
[0002] As the main storage reservoir of the global carbon cycle, soil converts carbon dioxide into carbonate forms (such as calcium carbonate, CaCO 3 ) through mineralization and fixes it in the soil, which is of great significance for mitigating climate change. As an important enzyme in the soil, urease can catalyze the hydrolysis of urea (CO(NH 2 )) 2 to generate ammonia (NH 3 ) and carbon dioxide, and provide conditions for the generation of carbonate ions (CO 3 2- ) by increasing the local pH value. However, the enzymatic hydrolysis process of urea in farmland may lead to carbon dioxide emissions and increase the risk of greenhouse gas emissions. Enzymatic mineralization is a green and sustainable carbon sequestration pathway that converts carbon dioxide in the environment into stable mineral forms through biochemical reactions. To mitigate the risk of greenhouse gas emissions, enzymatic mineralization has been used in the field of carbon sequestration. However, due to the large influence of environmental factors on the catalytic process of enzymes, the carbon sequestration efficiency is not high.
[0003] In view of this, it is necessary to design an improved carbon sequestration method co-catalyzed by urease and carbonic anhydrase to solve the above problems. Summary of the Invention
[0004] The purpose of the present invention is to provide a carbon sequestration method co-catalyzed by urease and carbonic anhydrase.
[0005] To achieve the above-mentioned invention purpose, the present invention provides a carbon sequestration method co-catalyzed by urease and carbonic anhydrase, including the following steps:
[0006] Adding urea, urease and carbonic anhydrase to a calcium source solution to obtain a carbon sequestration stock solution; allowing the carbon sequestration stock solution to stand for carbon sequestration to generate calcium carbonate precipitate.
[0007] Preferably, the pH of the carbon sequestration stock solution is 4-9.
[0008] Preferably, the concentration of urea in the carbon sequestration stock solution is 5 mM, the concentration of urease in the carbon sequestration stock solution is 2 mg / L, and the concentration of carbonic anhydrase in the carbon sequestration stock solution is 15 nM.
[0009] Preferably, the concentration of Ca 2+ in the calcium source solution is 5 mM.
[0010] Preferably, the ionic strength of the carbon sequestration stock solution is 1-100 mM.
[0011] Preferably, the temperature during the standing process is 25 °C and the time is 40 min.
[0012] Preferably, the carbon sequestration stock solution further comprises humic acid. After adding the humic acid, the concentration of humic acid in the carbon sequestration stock solution is 0 - 0.5 mg / L.
[0013] Preferably, the calcium source solution is CaCl 2 solution.
[0014] Preferably, the pH of the carbon sequestration stock solution is 7.
[0015] Preferably, the concentration of the humic acid is 0.5 mg / L.
[0016] The beneficial effects of the present invention are as follows:
[0017] 1. The carbon sequestration method by the synergistic catalysis of urease - carbonic anhydrase provided by the present invention uses urease and carbonic anhydrase together for carbon sequestration. It can utilize urease to catalyze the hydrolysis of urea to generate ammonia and carbon dioxide, and utilize carbonic anhydrase to accelerate the equilibrium reaction between carbon dioxide and water, promoting the formation of calcium carbonate, effectively improving the carbon sequestration efficiency; in addition, the present invention also adds a certain amount of humic acid to convert the calcium carbonate precipitate from amorphous to a more stable crystal phase, thereby enhancing the long - term stability of carbon storage.
[0018] 2. The carbon sequestration method by the synergistic catalysis of urease - carbonic anhydrase provided by the present invention controls the carbon sequestration conditions under specific conditions (pH, ionic strength), providing excellent external conditions for the formation of calcium carbonate and facilitating the formation of calcium carbonate precipitate. Description of the Drawings
[0019] Figure 1 It is the treatment results of four treatment groups in Example 1 of the present invention;
[0020] Figure 2 It is the graph of the calcium carbonate particle production amount and particle size results of four treatment groups in Example 1 of the present invention;
[0021] Figure 3 It is the in - situ Raman spectrum change graph of the phase change of calcium carbonate over time in the system under the treatment conditions of the UC group in Example 1 of the present invention;
[0022] Figure 4 It is the graph of the calcium carbonate particle number production amount and particle size results in Examples 1 - 4 of the present invention;
[0023] Figure 5 It is the in - situ Raman spectrum change graph of the phase change of calcium carbonate over time in the system under the treatment conditions of Example 4 of the present invention;
[0024] Figure 6This is the statistical analysis result of the number of calcium carbonate particles generated and the particle size under the pH conditions corresponding to Example 4 and Examples 5 to 6 of the present invention;
[0025] Figure 7 This is the statistical analysis result of the number of calcium carbonate particles generated and the particle size under the ionic strength conditions corresponding to Example 4 and Examples 7 to 8 of the present invention. Detailed implementation manners
[0026] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0027] Here, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, while other details less related to the present invention are omitted.
[0028] In addition, it should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.
[0029] The carbon fixation method by the synergistic catalysis of urease and carbonic anhydrase provided by the present invention includes the following steps: adding urea, urease and carbonic anhydrase to a calcium source solution to obtain a carbon fixation stock solution, and subjecting it to carbon fixation by standing at 25 °C for 40 min to generate calcium carbonate precipitate. Among them, the concentration of Ca in the calcium source solution is 5 mM, and it can be a CaCl solution; the concentration of urea in the carbon fixation stock solution is 5 mM, the concentration of urease in the carbon fixation stock solution is 2 mg / L, and the concentration of carbonic anhydrase in the carbon fixation stock solution is 15 nM. 2+ solution; the concentration of urea in the carbon fixation stock solution is 5 mM, the concentration of urease in the carbon fixation stock solution is 2 mg / L, and the concentration of carbonic anhydrase in the carbon fixation stock solution is 15 nM. 2 solution; the concentration of urea in the carbon fixation stock solution is 5 mM, the concentration of urease in the carbon fixation stock solution is 2 mg / L, and the concentration of carbonic anhydrase in the carbon fixation stock solution is 15 nM.
[0030] In the above technical solution, by synergistically fixing carbon with urease and carbonic anhydrase, urease can be used to catalyze the hydrolysis of urea to generate ammonia and carbon dioxide, and carbonic anhydrase can be used to accelerate the equilibrium reaction between carbon dioxide and water, promoting the generation of HCO, effectively promoting the generation of calcium carbonate precipitate, and improving the carbon fixation efficiency. Compared with the traditional single enzymatic mineralization reaction technology, the above method significantly increases the precipitation rate of calcium carbonate, and can show stronger adaptability and flexibility under different environmental conditions. The present invention has strong controllability, can optimize the carbon fixation effect according to different environmental conditions, and has broad application potential, especially in the fields of soil carbon sequestration and climate change mitigation. 3- In the above technical solution, by synergistically fixing carbon with urease and carbonic anhydrase, urease can be used to catalyze the hydrolysis of urea to generate ammonia and carbon dioxide, and carbonic anhydrase can be used to accelerate the equilibrium reaction between carbon dioxide and water, promoting the generation of HCO, effectively promoting the generation of calcium carbonate precipitate, and improving the carbon fixation efficiency. Compared with the traditional single enzymatic mineralization reaction technology, the above method significantly increases the precipitation rate of calcium carbonate, and can show stronger adaptability and flexibility under different environmental conditions. The present invention has strong controllability, can optimize the carbon fixation effect according to different environmental conditions, and has broad application potential, especially in the fields of soil carbon sequestration and climate change mitigation.
[0031] In some embodiments, the pH of the carbon sequestration stock solution is 4 - 9, such as 4, 7, 9, etc., preferably 7; the ionic strength is 1 - 100 mM. In the above technical solution, by controlling the pH and ionic strength of the carbon sequestration stock solution under the above conditions, excellent conditions can be provided for the formation of calcium carbonate.
[0032] Specifically, in some embodiments, to further improve the carbon sequestration efficiency and the stability of calcium carbonate precipitation, humic acid can be added to the carbon sequestration stock solution, and the concentration of humic acid in the resulting mixture after adding humic acid is 0 - 0.5 mg / L. In some other embodiments, organic matter containing humic acid, such as soil, can also be added. By adding a certain amount of humic acid, not only can the formation of calcium carbonate precipitation be accelerated, but also the transformation of amorphous calcium carbonate (ACC) to a stable crystal phase can be promoted, thereby enhancing the long-term stability of carbon storage.
[0033] The following further illustrates the carbon sequestration method with synergistic catalysis of urease - carbonic anhydrase provided by the present invention in combination with specific embodiments:
[0034] Example 1
[0035] This example provides a carbon sequestration method with synergistic catalysis of urease - carbonic anhydrase, which is carried out as follows: Add urea, urease, and carbonic anhydrase to a 5 mM CaCl 2 solution to ensure that in the carbon sequestration stock solution after uniform mixing, the concentration of urea is 5 mM, the urease concentration is 2 mg / L, and the carbonic anhydrase concentration is 15 nM, labeled as the UC group.
[0036] In addition, to compare the differences in carbon sequestration effects when only several of urea, urease, and carbonic anhydrase are added, three other treatment groups are also set, labeled as the CK group, U group, and C group respectively. Among them, the composition of the CK group is 5 mM CaCl 2 solution and 5 mM urea, the composition of the U group is 5 mM CaCl 2 solution, 5 mM urea and 2 mg / L urease, and the composition of the C group is 5 mM CaCl 2 solution and 15 nM carbonic anhydrase. The pH of the four treatment groups is 7.0, and the ionic strength is 1 mM.
[0037] The carbon sequestration stock solutions obtained from the above four treatment groups are introduced into the AFM liquid cell. In the ScanAsyst mode, using a ScanAsyst fluid + probe (the main component of the probe tip is Si, the spring constant is 0.7 N / m, and the tip radius is 2 nm), set a constant flow rate of 1 mL / h to ensure the conditions of steady-state kinetic nucleation, and in-situ observe the growth process of amorphous calcium carbonate (ACC) on the mica (001) surface, and count the density and particle size changes of calcium carbonate particles under different conditions. The results are as Figure 1 shown.Figure 1 A is the treatment result of the CK group. As can be seen from the figure, almost no white particles are visible on the surface of the mica sheet. This is because under this condition, the hydrolysis efficiency of urea is low, and the generated carbon dioxide and bicarbonate ions are insufficient to form calcium carbonate precipitation; Figure 1 B is the treatment result of the U group. As can be seen from the figure, obvious white particles appear on the surface of the mica sheet. The number of particles is small and the distribution is relatively sparse. This indicates that the addition of urease can catalyze the hydrolysis of urea to generate some carbon dioxide, thereby promoting the formation of calcium carbonate. However, due to the low utilization efficiency of carbon dioxide, the further generation of precipitation is limited; Figure 1 C is the treatment result of the C group. As can be seen from the figure, the white particles on the surface of the mica sheet compared with Figure 1 B, the number has increased significantly, and the particle distribution is more uniform. This shows that carbonic anhydrase promotes the precipitation of calcium carbonate by accelerating the reaction of carbon dioxide with water to generate more bicarbonate ions. However, due to the lack of an additional carbon dioxide source provided by urea hydrolysis, the number of particles is still limited; Figure 1 D is the treatment result of the UC group. As can be seen from the figure, the number of calcium carbonate precipitates on the mica sheet in this group is the largest and the distribution is the most dense. This shows that the synergistic effect of urease and carbonic anhydrase greatly improves the generation efficiency of calcium carbonate. Urease provides an abundant carbon dioxide source, while carbonic anhydrase accelerates the utilization of carbon dioxide, thereby significantly enhancing the generation of calcium carbonate precipitation and facilitating the improvement of carbon sequestration efficiency.
[0038] Further statistical analysis of the calcium carbonate particle generation amounts in the four treatment groups shows that the results are as Figure 2 shown in A. The results indicate that the calcium carbonate particle generation amount in the UC group is 2 times that of the C group and 2.8 times that of the U group, and the particle number in the CK group is almost negligible; the particle size results are as Figure 2 shown in B. The results indicate that there is no significant difference in the particle sizes of the calcium carbonate particles generated by different treatment groups, indicating that the addition of enzymes mainly affects the generation number of particles and has no obvious regulatory effect on the particle size.
[0039] Under the treatment conditions of the UC group, the in-situ Raman spectrum change diagram of the phase change of calcium carbonate in the system is as Figure 3 shown. As can be seen from the figure, in the initial stage, the characteristic peak at 1080 cm -1 mainly appears in the Raman spectrum, indicating that the system is mainly composed of ACC (amorphous calcium carbonate); as time goes by, ACC gradually transforms into stable calcite, and its characteristic peak at 1085 cm -1 gradually increases and finally dominates. The whole phase change process is relatively slow, and it takes about 4 h to completely transform into calcite.
[0040] Examples 2 to 4
[0041] Examples 2 to 4 are different from the UC group in Example 1 in that different concentrations of humic acid are added, and carbon sequestration is achieved in the following manner: Urea, urease, carbonic anhydrase, and soil organic matter humic acid are added to a 5 mM CaCl 2 solution to ensure that in the carbon sequestration stock solution after uniform mixing, the concentration of urea is 5 mM, the concentration of urease is 2 mg / L, the concentration of carbonic anhydrase is 15 nM, and the concentration of humic acid is 0 - 0.5 mg / L. The humic acid concentrations in Examples 1 to 4 are shown in Table 1. The number of calcium carbonate particles under different humic acid concentrations is as Figure 4 shown in A. It can be seen from the figure that as the humic acid concentration increases, the growth rate of the number of calcium carbonate particles significantly accelerates. And at 40 min, the number of particles in the 0.5 mg / L HA group is the largest, far greater than other groups, indicating that the addition of HA can promote the formation of calcium carbonate in the dual-enzyme system, and its promoting effect increases with the increase of HA concentration; the results of the particle size of calcium carbonate particles are as Figure 4 shown in B. The results show that there are significant differences in the particle size of the generated calcium carbonate particles under different HA concentrations. As the HA concentration increases from 0 mg / L to 0.5 mg / L, the particle size gradually increases, indicating that HA can not only promote the formation of calcium carbonate, but also play a significant role in the growth and aggregation of particles.
[0042] Under the treatment conditions of Example 4, the in-situ Raman spectroscopy change diagram of the phase transformation of calcium carbonate in the system with time is as Figure 5 shown. Comparing it with Figure 4 , it can be seen that after adding humic acid, ACC (1080 cm -1 characteristic peak) is still the main component in the initial stage, but its conversion rate is significantly accelerated. At about 40 min, ACC gradually transforms into vaterite (1089 / 1075 cm -1 characteristic peak); as time continues to pass, at 70 min, the characteristic peak of calcite dominates, indicating that the presence of humic acid significantly shortens the time for the transformation of ACC to stable calcite and promotes the diversity of the crystal phase transformation path.
[0043] Table 1 Humic acid concentration settings in Examples 1 to 4
[0044] Item Humic acid concentration (mg / L) Example 1 0 Example 2 0.01 Example 3 0.1 Example 4 0.5
[0045] Examples 5 to 6
[0046] Examples 5 to 6 are different from Example 4 only in that the pH of the system is different from that of Example 4, and the remaining experimental conditions are the same as those of Example 4. The pH of Example 5 is 4.0, and the pH of Example 6 is 9.0. The statistical analysis results of the number of calcium carbonate particles generated under the corresponding pH conditions of Example 4 and Examples 5 to 6 are as Figure 6 shown in A, and the statistical analysis results of the particle size are asFigure 6 As shown in Figure B, it can be seen from the figure that when pH = 7, the number and rate of calcium carbonate particle formation are the highest, indicating that neutral conditions are most favorable for the formation of calcium carbonate; when pH = 9, the number of particles is the second, indicating that alkaline conditions have a certain promoting effect on calcium carbonate formation, but the effect is lower than that of neutral conditions; when pH = 4, the number of particles is the least and the formation rate is the lowest, indicating that calcium carbonate formation is inhibited under acidic conditions; this may be related to the relatively high solubility of calcium carbonate under acidic conditions. There is no significant difference in the particle size of calcium carbonate particles formed under different pH conditions, indicating that pH has little effect on particle size regulation and mainly affects the formation rate and number of particles.
[0047] Examples 7 to 8
[0048] The differences between Examples 7 to 8 and Example 4 are only as follows: the ionic strength of the system is different from that of Example 4, and the rest of the experimental conditions are the same as those of Example 4. The ionic strength of Example 7 is 10 mM, and the ionic strength of Example 8 is 100 mM. The statistical analysis results of the number of calcium carbonate particles formed under the corresponding ionic strength conditions of Example 4 and Examples 7 to 8 are as Figure 7 shown in Figure A, and the statistical analysis results of the particle size are as Figure 7 shown in Figure B. It can be seen from the figure that as the ionic strength increases, the number of particles shows a significant downward trend, and the formation rate also decreases accordingly, indicating that a lower ionic strength is beneficial to the formation of calcium carbonate, and high ionic strength has a strong inhibitory effect on calcium carbonate formation. This may be because the process of aggregation and nucleation of bicarbonate ions and calcium ions is inhibited under high ionic strength; there is no significant difference in the particle size of calcium carbonate particles formed under different ionic strengths, indicating that ionic strength has little effect on particle size but significantly affects the efficiency and number of particle formation. Although both pH and ionic strength have significant effects on the formation number and rate of calcium carbonate, neither of them has an obvious regulatory effect on particle size, indicating that their main role is to regulate the nucleation and formation efficiency of particles rather than the particle growth process.
[0049] The above examples are only used to illustrate the technical solutions of the present invention and are not restrictive. Although the present invention has been described in detail with reference to preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.
Claims
1. A carbon fixation method using urease-carbonic anhydrase synergistic catalysis, characterized in that: The steps include: Urea, urease and carbonic anhydrase are added to a calcium source solution to obtain a carbon fixation stock solution; the carbon fixation stock solution is allowed to stand to fix carbon and generate calcium carbonate precipitation.
2. The carbon fixation method according to claim 1, characterized in that: The pH of the carbon-fixing stock solution is 4-9.
3. The carbon fixation method according to claim 1 or 2, characterized in that: The concentration of urea in the carbon-fixing stock solution is 5 mM, the concentration of urease in the carbon-fixing stock solution is 2 mg / L, and the concentration of carbonic anhydrase in the carbon-fixing stock solution is 15 nM.
4. The carbon fixation method according to claim 1, characterized in that: The calcium source solution contains Ca 2+ The concentration is 5mM.
5. The carbon fixation method according to claim 1, characterized in that: The ionic strength of the carbon-fixing stock solution is 1-100 mM.
6. The carbon fixation method according to claim 1, characterized in that: The temperature of the static process is 25°C and the time is 40 minutes.
7. The carbon fixation method according to claim 1, characterized in that: The carbon-fixing stock solution also includes humic acid. After the humic acid is added, the concentration of humic acid in the carbon-fixing stock solution is 0-0.5 mg / L.
8. The carbon fixation method according to claim 1, wherein the calcium source solution is a CaCl2 solution.
9. The carbon fixation method according to claim 2, characterized in that: The pH of the carbon-fixing stock solution is 7.
10. The carbon fixation method according to claim 7, characterized in that: The concentration of the humic acid is 0.5 mg / L.