Method for promoting microalgae carbon sequestration by amine degradation product based on amine method carbon capture

Abstract

The invention discloses a method for promoting microalgae carbon sequestration based on amine degradation products of amine method carbon capture. The method specifically comprises the following steps: (1) extracting and separating an amine degradation product; (2) adding the extracted amine degradation product into a microalgae culture solution; (3) inoculating microalgae into the culture solution containing the amine degradation product; (4) introducing flue gas CO2 into the culture solution, adjusting the pH value to 7-8, and stopping introducing gas; (5) when the pH value rises to 10-11, repeating the step (4) until the microalgae reach a mature period; and (6) harvesting a mature microalgae product. An amino functional group in the amine degradation product reacts with CO2, so that the mass transfer process of CO2 is enhanced; besides, most of amine degradation products are carboxylic acid amine salts, and as amphoteric compounds, the amine degradation products have a good pH buffering effect and can effectively reduce damage to microalgae cells in the high-concentration CO2 ventilation process. Meanwhile, the carboxylic acid amine salt is beneficial to hydrolysis of a product after CO2 is absorbed into inorganic carbonate, so that the carbon sequestration efficiency of the microalgae is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental control and pollution control, and particularly relates to a method for promoting microalgae carbon fixation by amine degradation products based on amine carbon capture. Background Art

[0002] The world's annual CO emissions from the combustion of fossil fuels such as oil, coal, and natural gas 2 More than 35Gt, atmospheric CO 2 The concentration continues to increase, and the global environmental problems it causes, such as greenhouse effect, sea level rise, and extreme climate, are becoming increasingly serious. 2 Long-term stable concentrated emission source. CO after combustion 2 Capture technology is the key to achieving CO 2 An effective way to control and reduce concentration. Chemical absorption, especially the method using organic alcohol amine aqueous solution as absorbent, has become the preferred technology for promoting global carbon emission reduction and achieving China's "dual carbon" goals due to its efficient separation ability and absorbent activity. Commonly used organic amine solvents include monoethanolamine (MEA), 2-amino-2-methyl-1-propanol (AMP), hydroxyethylethylenediamine (AEEA) or piperazine (PZ).

[0003] Since flue gas often contains smoke, H 2 O, O 2 、SO x Impurities such as CO2 can poison the amine solution, and the absorption tower of the capture system usually operates at a higher temperature. 2 The process of irreversible chemical reaction with impurity molecules in the flue gas and the generation of stable substances is called absorbent degradation. 2 The concentration is about 10%, which makes oxidative degradation the main degradation mechanism during absorbent degradation. Studies have shown that the oxidative degradation of all amines produces carboxylic acids, such as formic acid, acetic acid or glycolic acid. Carboxylic acids react with amines to form heat-stable salts. The formation of carboxylic acids and their reaction with amines are the main part of the oxidative degradation reaction. These acids can cause corrosion and scaling problems in the capture device, and because they react with amines to form heat-stable salts (HSSs) or heat-stable amine salts (HSASs), they aggravate the degradation reaction of amines. Since carboxylic acids are more acidic than carbonic acid, these heat-stable salts cannot be desorbed in the desorber and eventually accumulate in the solution. The degradation of the absorbent not only leads to the loss of absorbent and CO 2The decline in absorption capacity also requires regular replenishment of absorbents, thereby increasing operating costs. At the same time, phenomena such as corrosion and solution foaming caused by degradation products also shorten the equipment life, and volatile degradation products may also pollute the environment. Therefore, it becomes crucial to regularly clean up amine degradation products. Currently, there is still a lack of mature technologies for the effective treatment of amine degradation products after cleaning. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for promoting microalgae carbon sequestration by amine degradation products based on amine-based carbon capture, to solve the existing problems in the treatment of amine degradation products, effectively improve the environmental impact, and at the same time enhance the carbon sequestration performance of microalgae.

[0005] To achieve the above purpose, a method for promoting microalgae carbon sequestration by amine degradation products based on amine-based carbon capture according to the present invention includes introducing amine degradation products into the microalgae culture system to improve the carbon sequestration efficiency of microalgae, thereby providing a new technical path for carbon emission reduction and environmental protection. The specific steps are as follows:

[0006] (1) Extract and separate amine degradation products;

[0007] (2) Add the extracted amine degradation products to the microalgae culture solution;

[0008] (3) Inoculate microalgae into the culture solution containing amine degradation products;

[0009] (4) Introduce flue gas CO 2 , adjust the pH to 7 - 8 and then stop ventilation;

[0010] (5) When the pH value rises to 10 - 11, repeat step (4) until the microalgae reach the mature stage;

[0011] (6) Harvest the mature microalgae products.

[0012] Specifically, in step (1), the extractant is a non-polar organic solvent, and the non-polar organic solvent includes but is not limited to ether or benzene.

[0013] Specifically, in step (1), the amine degradation products are mainly carboxylamine salts, which are formed by the reaction of carboxylic acids and amines. The carboxylic acids include but are not limited to formic acid, acetic acid or glycolic acid, and the amines include but are not limited to monoethanolamine, 2-amino-2-methyl-1-propanol, hydroxyethyl ethylenediamine or piperazine.

[0014] Specifically, in step (2), the mass ratio of amine degradation products to the microalgae culture solution is 0.05 - 0.15%.

[0015] Specifically, the microalgae described in step (3) are algae at any growth stage, preferably microalgae at the logarithmic growth stage. The microalgae include but are not limited to Chlorella pyrenoidosa, Scenedesmus, Spirulina, etc., and the initial concentration of the microalgae is 0.1 - 0.3 g / L.

[0016] Specifically, the flue gas CO 2 in step (4) is a mixed gas of 10 - 15% CO 2 and 90 - 85% N 2 , and the flue gas ventilation rate is 10 - 100 mL / min.

[0017] Specifically, in step (6), a solid-liquid separation method is used to harvest the microalgae product.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The present invention can realize the reuse of amine degradation products based on amine-based carbon capture;

[0020] (2) The amine degradation products contain amino functional groups, and the mass transfer process of CO 2 is strengthened by reacting with CO 2 ;

[0021] (3) Most of the amine degradation products are carboxylate amines. As amphoteric compounds, they have good pH buffering effects and can effectively reduce the damage to microalgae cells during the ventilation process of high-concentration CO 2 ;

[0022] (4) The carboxylate amines help the products after absorbing CO 2 to hydrolyze into inorganic carbonates, thereby significantly improving the carbon fixation efficiency of microalgae. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a curve graph of the change in microalgae biomass concentration under the addition of MEA and different MEA carboxylates.

[0024] Figure 2 It is a curve graph of the change in microalgae biomass concentration under the addition of AMP and different AMP carboxylates.

[0025] Figure 3 It is a curve graph of the change in the pH of the culture solution under the addition of MEA and different MEA carboxylates.

[0026] Figure 4 It is a curve graph of the change in the concentration of dissolved inorganic carbon in the culture solution under the addition of MEA and different MEA carboxylates

[0027] Figure 5 It is a bar graph of the total superoxide dismutase activity of microalgae under the addition of MEA and different MEA carboxylates.

[0028] Figure 6 Scanning electron micrographs of microalgae cells with the addition of blank (a), MEA (b), MEA formate (c), MEA acetate (d), and MEA glycolate (e). Detailed implementation manners

[0029] To more clearly illustrate the content of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0030] The BG-11 liquid medium used in the following examples of the present invention has the composition shown in Tables 1 and 2. The distilled water and the dissolved chemical reagents in the medium are sterilized using a high-temperature and high-pressure sterilizer at a temperature of 121 °C for 30 min.

[0031] Table 1 BG-11 medium

[0032]

[0033] Table 2 Composition of solution A5 in Table 1

[0034]

[0035]

[0036] Example 1

[0037] (1) Inoculate the concentrated Chlorella pyrenoidosa algal solution into 1.0 L of BG-11 culture medium at an initial biomass concentration of 0.15 g / L, and pre-culture the microalgae under the following conditions: the temperature is 25 °C, the LED lamp tube provides illumination, the illumination intensity is 4000 Lux, the light-dark ratio is 12 h:12 h, and a 15% CO 2 + 85% N 2 mixed gas is aerated into the culture medium at a flow rate of 50 mL / min until the pH of the microalgae culture medium drops between 7 and 8;

[0038] (2) Wait until the pH rises to 10 - 11, repeat the above steps, and culture until the microalgae reach the mature stage;

[0039] (3) Measure the biomass concentration every 24 h, and measure DIC every 50 min after aeration;

[0040] (4) Centrifuge the microalgae culture medium to harvest microalgae cells, measure the SOD enzyme activity, and scan the morphology of the microalgae cells.

[0041] Example 2

[0042] (1) Add 0.05 wt% MEA and 0.05 wt% AMP to 1.0 L of BG-11 culture medium respectively.

[0043] (2) Inoculate the concentrated Chlorella pyrenoidosa algal solution into 1.0 L of BG-11 culture medium at an initial biomass concentration of 0.15 g / L, and pre-culture the microalgae under the following conditions: the temperature is 25 °C, the LED lamp tube provides light, the light intensity is 4000 Lux, the light-dark ratio is 12 h:12 h, and a mixture of 15% CO 2 + 85% N 2 is aerated into the culture medium at a flow rate of 50 mL / min until the pH of the microalgae culture medium drops to between 7 and 8;

[0044] (3) Wait until the pH rises to 10 - 11, repeat the above steps, and culture until the microalgae reach the mature stage;

[0045] (4) Measure the biomass concentration every 24 h, and measure DIC every 50 min after aeration;

[0046] (5) Centrifuge the microalgae culture medium to harvest microalgae cells, measure the SOD enzyme activity, and scan the morphology of microalgae cells.

[0047] Example 3

[0048] (1) Use the same mass of MEA and AMP as in Example 2, and respectively react with equimolar formic acid at 120 °C to prepare MEA formate and AMP formate, simulating one of the degradation products of MEA and AMP;

[0049] (2) Add the prepared MEA formate and AMP formate to 1.0 L of BG-11 culture medium respectively.

[0050] (3) Inoculate the concentrated Chlorella pyrenoidosa algal solution into 1.0 L of BG-11 culture medium at an initial biomass concentration of 0.15 g / L, and pre-culture the microalgae under the following conditions: the temperature is 25 °C, the LED lamp tube provides light, the light intensity is 4000 Lux, the light-dark ratio is 12 h:12 h, and a mixture of 15% CO 2 + 85% N 2 is aerated into the culture medium at a flow rate of 50 mL / min until the pH of the microalgae culture medium drops to between 7 and 8;

[0051] (4) Wait until the pH rises to 10 - 11, repeat the above steps, and culture until the microalgae reach the mature stage;

[0052] (5) Measure the biomass concentration every 24 h, and measure DIC every 50 min after aeration;

[0053] (6) Centrifuge the microalgae culture medium to harvest microalgae cells, measure the SOD enzyme activity, and scan the morphology of microalgae cells.

[0054] Example 4

[0055] (1) Use the same mass of MEA and AMP as in Example 2, and react them with equimolar acetic acid at 120 °C respectively to prepare MEA acetate and AMP acetate, simulating one of the degradation products of MEA and AMP;

[0056] (2) Add the prepared MEA acetate and AMP acetate to 1.0 L of BG-11 culture medium respectively.

[0057] (3) Inoculate the Chlorella pyrenoidosa concentrated algal solution into 1.0 L of BG-11 culture medium at an initial biomass concentration of 0.15 g / L, and pre-culture the microalgae under the following conditions: the temperature is 25 °C, the LED lamp provides light, the light intensity is 4000 Lux, the light-dark ratio is 12 h:12 h, and a 15% CO 2 + 85% N 2 mixed gas is aerated into the culture medium at a flow rate of 50 mL / min until the pH of the microalgae culture medium drops between 7 and 8;

[0058] (4) Wait until the pH rises to 10 - 11, repeat the above steps, and culture until the microalgae reach the mature stage;

[0059] (5) Measure the biomass concentration every 24 h, and measure DIC every 50 min after aeration;

[0060] (6) Centrifuge the microalgae culture medium, harvest the microalgae cells, measure the SOD enzyme activity, and scan the microalgae cell morphology.

[0061] Example 5

[0062] (1) Use the same mass of MEA and AMP as in Example 2, and react them with equimolar glycolic acid at 120 °C respectively to prepare MEA glycolate and AMP glycolate, simulating one of the degradation products of MEA and AMP;

[0063] (2) Add the prepared MEA glycolate and AMP glycolate to 1.0 L of BG-11 culture medium respectively.

[0064] (3) Inoculate the Chlorella pyrenoidosa concentrated algal solution into 1.0 L of BG-11 culture medium at an initial biomass concentration of 0.15 g / L, and pre-culture the microalgae under the following conditions: the temperature is 25 °C, the LED lamp provides light, the light intensity is 4000 Lux, the light-dark ratio is 12 h:12 h, and a 15% CO 2 + 85% N 2 mixed gas is aerated into the culture medium at a flow rate of 50 mL / min until the pH of the microalgae culture medium drops between 7 and 8;

[0065] (4) Wait until the pH rises to 10 - 11, repeat the above steps, and cultivate until the microalgae reach the mature stage;

[0066] (5) Measure the biomass concentration every 24 h, and measure DIC every 50 min after aeration;

[0067] (6) Centrifuge the microalgae culture solution, harvest the microalgae cells, measure the SOD enzyme activity, and scan the morphology of the microalgae cells.

[0068] In Examples 1 - 5, the microalgae biomass concentration was measured every 24 h by the split - tube spectrophotometry at a wavelength of 680 nm.

[0069] The biomass productivity in Examples 1 - 5 was calculated by measuring the microalgae biomass concentration during the growth process. The calculation formula is as follows:

[0070]

[0071] P X : Maximum biomass productivity, g / (L·d);

[0072] t 0 : Starting time, d;

[0073] t 1 : Ending time, d;

[0074] M 0 : Biomass mass measured at the starting measurement time t 0 ; g;

[0075] M 1 : Biomass mass measured at the starting measurement time t 1 ; g.

[0076] Figure 1 is the curve graph of the change in microalgae biomass concentration under the addition of MEA and different MEA carboxylates. As shown in the figure, the addition of 0.05 wt% MEA can slightly increase the microalgae biomass concentration in the initial stage of cultivation, but after the 7th day of cultivation, the enhancing effect of MEA disappears and shows a negative effect; while the addition of different MEA carboxylates with relative mass can significantly increase the microalgae biomass concentration and is significantly higher than the enhancing effect of MEA. The maximum biomass concentrations corresponding to the blank, MEA, MEA formate, MEA acetate, and MEA glycolate are 0.85 g / L, 0.81 g / L, 0.95 g / L, 0.96 g / L, and 0.94 g / L respectively. MEA acetate achieves the maximum value, which is 12.9% higher than the blank culture group, and the microalgae growth reaches the stable stage at the 12th day of cultivation.

[0077] Figure 2It is a graph showing the change in microalgae biomass concentration under the addition of AMP and different AMP carboxylates. As shown in the graph, both 0.05 wt% AMP and different AMP carboxylates with relative mass can increase the biomass concentration of microalgae. The increasing order is: AMP glycolate > AMP acetate > AMP formate > AMP > blank. The corresponding maximum biomass concentrations are 1.26 g / L, 1.23 g / L, 1.17 g / L, 1.11 g / L, and 1.03 g / L respectively. AMP glycolate achieves the maximum value, which is 22.3% higher than the blank culture group. The growth of microalgae reaches the stationary phase at 12 days of cultivation.

[0078] Figure 3 It is a graph showing the change in pH of the culture solution under the addition of MEA and different MEA carboxylates. As shown in the graph, in the culture systems with the addition of MEA and MEA carboxylates, the rising rate of pH is higher than that of the blank control group, and in the culture systems with the addition of MEA carboxylates, the rising rate is more significant. The reason for this phenomenon is that the faster the growth rate of microalgae, the faster the consumption rate of inorganic salts, resulting in an accelerated rising rate of pH value.

[0079] Figure 4 It is a graph showing the change in the concentration of dissolved inorganic carbon in the culture solution under the addition of different MEA and MEA carboxylates. As shown in the graph, in the culture system with the addition of MEA, the concentration of dissolved inorganic carbon is lower than that of the blank control group, and the decreasing rate of dissolved inorganic carbon is equivalent to that of the blank group. While in the culture systems with the addition of MEA carboxylates, the concentration of dissolved inorganic carbon is higher than that of the blank control group, and the decreasing rate of dissolved inorganic carbon is also significantly higher than that of the blank control group.

[0080] Figure 5 It is a bar graph of the total superoxide dismutase activity of microalgae under the addition of different MEA and MEA carboxylates. SOD maintains the redox balance of microalgae cells by converting superoxide anion radicals into oxygen and hydrogen peroxide, thereby protecting cells from damage. As shown in the graph, compared with the blank control group, the SOD activity increases in the culture system with the addition of MEA, while the SOD activity decreases in the culture systems with the addition of MEA carboxylates. This indicates that MEA carboxylates have less toxicity to microalgae cells than MEA, and MEA carboxylates can reduce the damage of high-concentration CO2 to microalgae cells through pH buffering.

[0081] Figure 6 It is a scanning electron micrograph of microalgae cells under the addition of blank (a), MEA (b), MEA formate (c), MEA acetate (d), and MEA glycolate (e). As shown in the graph, MEA, MEA formate, MEA acetate, and MEA glycolate all have certain effects on the surface morphology of microalgae cells, but the effects of MEA carboxylates are significantly less than those of MEA.

Claims

1. A method for promoting microalgae carbon fixation by amine degradation products based on amine carbon capture, characterized in that: The specific steps include: (1) extracting and separating the amine degradation products; (2) adding the amine degradation products obtained by extraction to the microalgae culture solution; (3) inoculating microalgae into a culture solution containing amine degradation products; (4) Add flue gas CO2 to the culture medium, adjust the pH to 7-8, and then stop aeration; (5) When the pH value rises to 10 to 11, repeat step (4) until the microalgae reaches maturity; (6) Harvesting mature microalgae products.

2. The method for promoting microalgae carbon fixation by amine degradation products based on amine carbon capture according to claim 1, characterized in that: The extractant described in step (1) is a non-polar organic solvent, and the non-polar organic solvent is ether or benzene.

3. The method for promoting microalgae carbon fixation by amine degradation products based on amine carbon capture according to claim 1, characterized in that: In step (1), the amine degradation product is mainly carboxylic acid amine salt, which is generated by the reaction of carboxylic acid and amine, wherein the carboxylic acid is formic acid, acetic acid or glycolic acid, and the amine is monoethanolamine, 2-amino-2-methyl-1-propanol, hydroxyethylethylenediamine or piperazine.

4. The method for promoting microalgae carbon fixation by amine degradation products based on amine carbon capture according to claim 1, characterized in that: In step (2), the mass ratio of the amine degradation product to the microalgae culture solution is 0.05-0.15%.

5. The method for promoting microalgae carbon fixation by amine degradation products based on amine carbon capture according to claim 1, characterized in that: In step (3), the microalgae are microalgae in the logarithmic growth phase, the microalgae are Chlorella, Corallina or Spirulina, and the initial concentration of the microalgae is 0.1-0.3 g / L.

6. The method for promoting microalgae carbon fixation by amine degradation products based on amine carbon capture according to claim 1, characterized in that: The flue gas CO2 in step (4) is a mixed gas of 10-15% CO2 and 90-85% N2, and the flue gas ventilation rate is 10-100 mL / min.

7. The method for promoting microalgae carbon fixation by amine degradation products based on amine carbon capture according to claim 1, characterized in that: In step (6), the microalgae product is harvested by a solid-liquid separation method.

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