Method for producing biological energy based on natural semiconductor mineral-microalgae photoelectric conversion complex

Abstract

The invention relates to a method for producing biological energy based on a natural semiconductor mineral-microalgae photoelectric conversion complex, which comprises the following steps of: sequentially performing impurity removal, grinding and sieving on natural semiconductor minerals with a photoelectric conversion function to obtain natural semiconductor mineral particles, and performing lipophilic modification on the particles to obtain the biological energy based on the natural semiconductor mineral-microalgae photoelectric conversion complex. And co-culturing the modified microparticles and the microalgae, inducing the microalgae to synthesize more extracellular polymeric substances, adhering the microparticles to the body surface of the microalgae, and constructing physical and chemical association by using lipophilic functional groups of the microparticles and microalgae membrane lipid to construct the natural semiconductor mineral-microalgae photoelectric conversion complex. The natural semiconductor minerals in the complex convert light energy into electric energy, the converted electric energy is transmitted to the microalgae through physical and chemical association, and the microalgae take the received converted electric energy as additional supplementary energy to synthesize more clean biological energy sources such as biological oil, hydrogen, ethanol, methane and the like. And the efficiency of producing clean biological energy by the microalgae is improved.

Description

Technical Field

[0001] The present invention belongs to the field of new energy technology, and specifically relates to a method for producing bioenergy based on a natural semiconductor mineral-microalgae photoelectric conversion complex. Background Art

[0002] Using wastewater and waste gas as nutrient sources, and using the photosynthetic system of microalgae (hereinafter referred to as microalgae) to convert light energy into chemical energy and then synthesize bioenergy such as oil, hydrogen, and ethanol, can achieve an organic combination of carbon fixation, emission reduction, and production capacity. However, the photosynthetic system of microalgae has become highly stable after nearly 100 million years of evolution, and it is very difficult to improve its own light energy conversion efficiency.

[0003] The process of photosynthesis in microalgae begins by collecting light energy and releasing electrons in the center of photosynthetic system II (PSII) to convert light energy into electrical energy. The released electrons are then transferred to reductases through a series of electron carriers for various biochemical processes, including CO2 fixation, nutrient absorption, and lipid synthesis. At the same time, the protons produced by photosynthesis can drive the production of adenosine triphosphate, which serves as a key energy substrate in the growth and lipid production processes of microalgae. Therefore, improving the light energy collection and conversion of microalgae PSII will improve the efficiency of these processes. Studies have shown that the efficiency of microalgae PSII in capturing and converting light energy can be improved through a variety of biological methods such as constructing mutagenesis, selecting new algae strains, and genetic engineering. However, since the photosynthetic system of microalgae has become very stable after long-term evolution, it is very difficult to improve the photosynthetic efficiency of microalgae itself. It is necessary to develop extracellular auxiliary technologies to further improve the photosynthetic efficiency of microalgae and contribute to the early realization of large-scale production of microalgae bioenergy.

[0004] In this context, developing extracellular auxiliary technologies for the photosynthetic system of microalgae is of great value for improving microalgae growth and lipid production. Summary of the invention

[0005] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for producing bioenergy based on a natural semiconductor mineral-microalgae photoelectric conversion complex, which is specifically achieved through the following technical solutions: A method for producing bioenergy based on a natural semiconductor mineral-microalgae photoelectric conversion complex, the method comprising the following steps: S1: Soaking the natural semiconductor in a mixed liquid to remove microorganisms and metal oxide impurities on the surface of the natural semiconductor mineral; S2: Wash the natural semiconductor after impurities removal with distilled water for 3-5 times, and dry it at a temperature of 30-60°C after washing; S3: Grind the dried natural semiconductor mineral into particles using an ultrafine pulverizer, and pass through a 400-mesh sieve to obtain natural semiconductor mineral particles for later use; S4: transferring the natural semiconductor mineral particles into anhydrous ethanol water, using ultrasonic dispersion to disperse them uniformly, adding sodium hexametaphosphate and 3-(trimethoxysilyl)propyl methacrylate to the anhydrous ethanol, reacting under continuous stirring, centrifuging, collecting the precipitate, and drying the precipitate to obtain modified particles; S5: adding the modified microparticles into a culture solution of microalgae in a certain proportion, adding a quaternary ammonium salt surfactant, and obtaining a mixed culture solution of microalgae; S6: placing the microalgae mixed culture solution under environmental conditions suitable for the growth of microalgae, using continuous light culture, and culturing the microalgae until the algae cell density reaches a maximum value; S7: Centrifuge the mixed culture solution of microalgae, collect algae cells, and re-inoculate the algae cells into a low-nitrogen element culture solution or a low-sulfur element culture solution to induce the microalgae to synthesize bioenergy.

[0006] Furthermore, the natural semiconductor includes any one of nannosite, goethite, and hematite.

[0007] Furthermore, the mixed liquid in S1 includes 1 mol / L nitric acid aqueous solution, 1 mol / L NaOH aqueous solution, 95% ethyl acetate aqueous solution (v / v) and 80% (v / v) ethanol aqueous solution, and the natural semiconductor is immersed in the mixed liquid for 1-3 hours.

[0008] Furthermore, the mass concentration w / v of sodium hexametaphosphate in S4 is 1-3%, the mass concentration w / v of 3-(trimethoxysilyl)propyl methacrylate is 2-5%, the reaction time is 0.5-3h, the centrifugation conditions are: 6000-8000 rpm, 10 min, 4°C, and the drying temperature is 30-60°C.

[0009] Furthermore, in S5, the mass ratio of the microparticles to the dry weight of the microalgae is 1:10-100, and the quaternary ammonium salt surfactant is dodecyl dimethyl benzyl ammonium chloride, and the amount added is such that the final concentration of the surfactant is 0.01-0.1 mg / L.

[0010] Furthermore, the microalgae are selected from green algae or blue algae, including but not limited to Chlamydomonas reinhardtii, Chlorella pyrenoidosa, Chlorella sorokinensis, Spirulina, Scenedesmus, the environmental temperature for the growth of green algae is 25-28°C, and the environmental temperature for the growth of blue algae is 30-35°C.

[0011] Furthermore, the light intensity of the light culture in S6 was 50-250 µmol / cm 2 / sec.

[0012] Furthermore, the centrifugation conditions in S7 are 6000-8000 rpm, 10 min, 4°C, the low nitrogen element culture medium refers to the culture medium with a total nitrogen concentration of less than 10 mg / L, and the low sulfur element culture medium refers to the culture medium with a total sulfur concentration of less than 1 mg / L.

[0013] Furthermore, bioenergy includes but is not limited to bio-oil, bio-hydrogen, bio-ethanol, and bio-methane.

[0014] The present invention removes impurities, grinds, and sieves natural semiconductor minerals with photoelectric conversion functions in sequence, chemically modifies natural semiconductor mineral particles, improves the lipophilicity of natural semiconductor minerals, co-cultivates the modified natural semiconductor mineral particles with microalgae, adds an inducer, induces the microalgae to synthesize and secrete more extracellular polymers, adheres the natural semiconductor minerals to the surface of the microalgae, and uses the lipophilic functional groups of the natural semiconductor minerals to establish chemical associations with the membrane lipids of the microalgae. The natural semiconductor minerals convert light energy into electrical energy, and the converted electrical energy is transmitted to the microalgae, and the microalgae uses the converted electrical energy as additional supplementary energy to synthesize more bio-oil, hydrogen, ethanol, methane and other bio-energy, thereby improving the efficiency of microalgae in producing bio-energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a scanning electron microscope image of the natural mineral and microalgae complex prepared in the example; Figure 2 This is a diagram of the photoelectric conversion efficiency of natural semiconductor minerals in the composite prepared in the example; Figure 3 A comparison chart of the maximum photosynthetic electron transfer rate of the microalgae in the complex prepared in the example and the maximum photosynthetic electron transfer rate of the microalgae alone; Figure 4 The figure is a comparison chart of the oil content and oil yield of the microalgae in the composite prepared in the example and the oil content and oil yield of the microalgae alone. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings in order to better understand the technical solution. Example

[0017] A method for producing bioenergy based on a natural semiconductor mineral-microalgae photoelectric conversion complex: Step 1): Soak the natural semiconductor mineral hematite in 1 mol / L nitric acid aqueous solution, 1 mol / L NaOH aqueous solution, 95% ethyl acetate aqueous solution (v / v) and 80% (v / v) ethanol aqueous solution for 3 h to remove impurities such as microorganisms and metal oxides on the surface of the hematite; Step 2): Wash the impurity-free hematite 3 times with distilled water, and then dry at 60°C; Step 3): Grind the hematite into particles using an ultrafine pulverizer, pass through a 400-mesh sieve to obtain hematite particles for later use; Step 4): The hematite particles were transferred into anhydrous ethanol water (w / v=1:100), dispersed evenly using ultrasound, 2% (w / v) sodium hexametaphosphate and 1.5% (w / v) 3-(trimethoxysilyl) propyl methacrylate were added to the anhydrous ethanol, reacted for 3 h under continuous stirring conditions, centrifuged (8000 rpm, 10 min, 4°C) to collect the precipitate, and dried the precipitate at 60°C to obtain modified particles; Step 5): Add the modified microparticles to the culture solution of Scenedesmus in a certain ratio (w / w=1:50), add a certain concentration of dodecyldimethylbenzylammonium chloride (final concentration is 0.1 mg / L), and obtain a mixed culture solution of Scenedesmus; Step 6): Place the mixed culture solution of Scenedesmus in an environment suitable for the growth of microalgae (25°C, continuous light culture, light intensity 200 µmol / cm2 / sec), and culture the Scenedesmus cell density to the maximum value (the absorbance value of the algae solution at 680 nm OD680 = 2.10); Step 7): The mixed culture solution of Scenedesmus was centrifuged (6000 rpm, 10 min, 4°C), the algal cells were collected, and the algal cells were re-inoculated into a low-nitrogen (total nitrogen concentration <9 mg / L) culture solution under the environmental conditions for the growth of microalgae (25°C, continuous light culture, light intensity 200 µmol / cm 2 / sec), inducing microalgae to synthesize more oil.

[0018] The scanning electron microscope image of the natural mineral and microalgae complex prepared in the above embodiment is as follows: Figure 1 As shown, from Figure 1 It can be seen that after the synthesis steps of the present invention, a close combination of natural minerals and microalgae can be obtained.

[0019] The photoelectric conversion efficiency of the natural semiconductor mineral in the composite prepared in this embodiment is as follows: Figure 2 As shown by Figure 2 It can be seen that natural semiconductor minerals with photoelectric conversion capabilities can convert solar energy into electrical energy, and their highest photoelectric conversion efficiency is 3.2×10-2µA.

[0020] The maximum photosynthetic electron transfer rate of the microalgae in the complex prepared in this embodiment is compared with the maximum photosynthetic electron transfer rate of the microalgae alone. Figure 3 As shown by Figure 3It can be seen that the maximum photoelectron transfer efficiency of the microalgae in the natural semiconductor mineral-microalgae photoelectric conversion complex constructed by the present invention is significantly greater than that of the microalgae itself, indicating that the constructed complex provides more photoelectrons for the microalgae than the microalgae itself.

[0021] The oil content and oil yield of the microalgae in the composite prepared in this example are compared with the oil content and oil yield of the microalgae alone. Figure 4 As shown by Figure 4 It can be seen that the microalgae oil content and oil yield in the natural semiconductor mineral-microalgae photoelectric conversion complex constructed by the present invention are significantly higher than those of the microalgae themselves, indicating that the constructed complex can significantly promote the clean bioenergy production efficiency of microalgae.

[0022] It was measured that the oil content and yield of Scenedesmus in the complex constructed in this example were 41.34% and 18.97 mg / L / d, respectively, which were significantly higher than 31.80% and 13.51 mg / L / d when Scenedesmus was cultured under the same conditions (p < 0.01).

Claims

1. A method for producing bioenergy based on a natural semiconductor mineral-microalgae photoelectric conversion complex, characterized in that: The method uses the following steps: S1: Soaking the natural semiconductor in a mixed liquid to remove microorganisms and metal oxide impurities on the surface of the natural semiconductor mineral; S2: Wash the natural semiconductor after impurities removal with distilled water for 3-5 times, and dry it at a temperature of 30-60°C after washing; S3: Grind the dried natural semiconductor mineral into particles using an ultrafine pulverizer, and pass through a 400-mesh sieve to obtain natural semiconductor mineral particles for later use; S4: transferring the natural semiconductor mineral particles into anhydrous ethanol water, using ultrasonic dispersion to disperse them uniformly, adding sodium hexametaphosphate and 3-(trimethoxysilyl)propyl methacrylate to the anhydrous ethanol, reacting under continuous stirring, centrifuging, collecting the precipitate, and drying the precipitate to obtain modified particles; S5: adding the modified microparticles into a culture solution of microalgae in a certain proportion, adding a quaternary ammonium salt surfactant, and obtaining a mixed culture solution of microalgae; S6: placing the microalgae mixed culture solution under environmental conditions suitable for the growth of microalgae, using continuous light culture, and culturing the microalgae until the algae cell density reaches a maximum value; S7: Centrifuge the mixed culture solution of microalgae, collect algae cells, and re-inoculate the algae cells into a low-nitrogen element culture solution or a low-sulfur element culture solution to induce the microalgae to synthesize bioenergy.

2. A method for producing bioenergy based on a natural semiconductor mineral-microalgae photoelectric conversion complex as claimed in claim 1, characterized in that: Natural semiconductors include any of nannosite, goethite, and hematite.

3. The method for producing bioenergy based on natural semiconductor mineral-microalgae photoelectric conversion complex according to claim 1, characterized in that: The mixed liquid in S1 includes 1 mol / L nitric acid aqueous solution, 1 mol / L NaOH aqueous solution, 95% ethyl acetate aqueous solution (v / v) and 80% (v / v) ethanol aqueous solution. The natural semiconductor is immersed in the mixed liquid for 1-3 hours.

4. The method for producing bioenergy based on natural semiconductor mineral-microalgae photoelectric conversion complex according to claim 1, characterized in that: The mass concentration w / v of sodium hexametaphosphate in S4 is 1-3%, the mass concentration w / v of 3-(trimethoxysilyl)propyl methacrylate is 2-5%, the reaction time is 0.5-3h, the centrifugation conditions are: 6000-8000 rpm, 10 min, 4°C, and the drying temperature is 30-60°C.

5. The method for producing bioenergy based on natural semiconductor mineral-microalgae photoelectric conversion complex according to claim 1, characterized in that: The mass ratio of microparticles to microalgae dry weight in S5 is 1:10-100, and the quaternary ammonium salt surfactant is dodecyl dimethyl benzyl ammonium chloride, and the amount added is such that the final concentration of the surfactant is 0.01-0.1 mg / L.

6. The method for producing bioenergy based on natural semiconductor mineral-microalgae photoelectric conversion complex according to claim 1, characterized in that: The microalgae are green algae or blue algae, including but not limited to Chlamydomonas reinhardtii, Chlorella pyrenoidosa, Chlorella sorokinensis, Spirulina, Scenedesmus. The environmental temperature for the growth of green algae is 25-28°C, and the environmental temperature for the growth of blue algae is 30-35°C.

7. The method for producing bioenergy based on natural semiconductor mineral-microalgae photoelectric conversion complex according to claim 1, characterized in that: The light intensity for S6 light culture is 50-250 µmol / cm 2 / sec.

8. The method for producing bioenergy based on natural semiconductor mineral-microalgae photoelectric conversion complex according to claim 1, characterized in that: The centrifugation conditions in S7 are 6000-8000 rpm, 10 min, 4°C. The low-nitrogen culture medium refers to a culture medium with a total nitrogen concentration of less than 10 mg / L, and the low-sulfur culture medium refers to a culture medium with a total sulfur concentration of less than 1 mg / L.

9. The method for producing bioenergy based on natural semiconductor mineral-microalgae photoelectric conversion complex according to claim 1, characterized in that: Bioenergy includes but is not limited to bio-oil, bio-hydrogen, bio-ethanol and bio-methane.

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