Sodium alginate / nanocellulose bioactive capsule as well as preparation method and application thereof

Abstract

The invention discloses a sodium alginate / nanocellulose bioactive capsule as well as a preparation method and application thereof. Microcystic toxins in a water body can be efficiently removed. The preparation method comprises the following steps: firstly, dissolving sodium alginate and carboxymethyl cellulose nanofibers in deionized water, and stirring to ensure full dissolution; secondly, adding a functional degrading bacterium suspension into the solution, preferably adding charcoal, uniformly mixing and degassing to form a double-gel biological mixed solution; and finally, dropwise adding the mixed solution into a cross-linking agent solution through a physical cross-linking method, and cross-linking to form the bioactive capsule. The capsule combines the biodegradability and biocompatibility of sodium alginate and carboxymethyl cellulose nanofibers, the high specific surface area of biochar enhances the physical adsorption capacity, and the biodegradation effect of functional degrading bacteria realizes the synergistic effect of physical adsorption and biodegradation, so that the biodegradability and biocompatibility of sodium alginate and carboxymethyl cellulose nanofibers are improved. The microcystic toxin pollution in water bodies of lakes and rivers can be effectively treated.

Description

Technical Field

[0001] The invention relates to the field of water treatment, and in particular to a sodium alginate / nanocellulose bioactive capsule, a preparation method and application thereof. Background Art

[0002] Climate change and the interference of human production and life have led to the occurrence of eutrophication of water bodies, thus triggering large-scale algal blooms. After the algal bloom, the cyanobacteria and other cells in it will release algal organic matter into the surrounding water bodies at a specific stage, including microcystins (MCs), posing a serious threat to the safety of the water environment. Although existing methods have attempted to solve the problem of microcystin pollution caused by eutrophication of water bodies and algal blooms, they still have significant deficiencies in removal efficiency, environmental adaptability and cost-effectiveness. A more efficient, economical and environmentally friendly solution is urgently needed.

[0003] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0004] The main purpose of the present invention is to overcome the defects existing in the above-mentioned background technology and provide sodium alginate / nanocellulose bioactive capsules, preparation methods and applications.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] In a first aspect of the present invention, a method for preparing a sodium alginate / nanocellulose bioactive capsule comprises the following steps:

[0007] S1, dissolving sodium alginate and carboxymethyl cellulose nanofibers in deionized water, and stirring to fully dissolve them;

[0008] S2, adding a functional degradation bacterial suspension, preferably also adding biochar, stirring and mixing, and degassing to obtain a double gel biological mixed solution;

[0009] S3. Through the physical cross-linking method, the double gel mixed solution is dropped into the cross-linking agent CaCl2 solution for cross-linking to obtain a bioactive capsule.

[0010] Furthermore, the cross-linking agent solution is a CaCl2 solution.

[0011] Furthermore, the concentration of the CaCl2 solution is 1.5%, and the cross-linking time is 40 minutes.

[0012] Furthermore, the method further includes the step of culturing the functional degradation bacteria used in step S2.

[0013] Furthermore, the cultivation of the functional degradation bacteria includes: using LB liquid culture medium to activate and revive the freeze-dried and preserved microcystin-degrading functional bacteria, placing them in a shaking incubator for static cultivation, transferring the revived functional bacteria to LB solid culture medium for cultivation, screening pure bacteria and transferring them to liquid culture medium for expanded cultivation; taking out the cultured bacterial liquid to centrifuge and separate the functional bacteria, and dispersing and suspending them in physiological saline.

[0014] Furthermore, the weight ratio of the sodium alginate to the carboxymethyl cellulose nanofibers is 2.5:1.

[0015] Furthermore, the added amount of the biochar is 6% of the weight of the sodium alginate.

[0016] Furthermore, the OD600 value of the functional degradation bacteria suspension is 2.0.

[0017] In the second aspect of the present invention, sodium alginate / nanocellulose bioactive capsules are prepared by the method described.

[0018] In the third aspect of the present invention, the sodium alginate / nanocellulose bioactive capsules prepared by the method are used to remove microcystins in water.

[0019] The present invention has the following beneficial effects:

[0020] The present invention provides an efficient and environmentally friendly sodium alginate / nanocellulose bioactive capsule, a preparation method and an application thereof, which effectively solve the problem of removing microcystins in water bodies. The method utilizes sodium alginate and carboxymethyl cellulose nanofibers, two high-performance biomaterials with biodegradability, biocompatibility and green economy, to construct a tough hydrogel shell through physical cross-linking to form an interpenetrating polymer network. Further preferably, by carrying biochar, not only the physical adsorption capacity of the capsule is enhanced, but also a good growth environment is provided for functional degradation bacteria due to its rich pore structure and high specific surface area. This design realizes the synergistic effect of physical adsorption and biodegradation, and effectively improves the removal efficiency of microcystins. In addition, the source of biochar is the resource utilization of agricultural and forestry waste, which further emphasizes the environmental protection characteristics of the present invention. Through this innovative capsule preparation method, the present invention can construct a degradation system that is resistant to interference from environmental factors, which is particularly suitable for the effective treatment of microcystin pollution in lakes and rivers, and provides an innovative solution for water environment safety.

[0021] Other beneficial effects of the embodiments of the present invention will be further described below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a comparison chart of the removal performance of the composite materials prepared in Examples 1 and 2 of the present invention and Comparative Example 1.

[0023] Figure 2 These are SEM images of the composite materials prepared in Examples 1 and 2 of the present invention and Comparative Example 1.

[0024] Figure 3 The removal efficiency of microcystin under the influence of coexisting ions of the sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsules prepared in Example 1 of the present invention.

[0025] Figure 4 The removal efficiency of microcystin at different initial pH values ​​of sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsules and equal amounts of functional degradation bacteria prepared in Example 1 of the present invention.

[0026] Figure 5 The sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsules prepared in Example 1 of the present invention and the removal efficiency of microcystin under different initial pH and coexistence of natural organic matter.

[0027] Figure 6 The kinetic curve of the degradation of microcystin in actual lake and river water by sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsules prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0028] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope and application of the present invention.

[0029] Hydrogel encapsulation is an effective solution to enhance the biodegradation of microcystins. Sodium alginate and carboxymethyl cellulose nanofibers are high-performance biomaterials with biodegradability, biocompatibility and green economy. At the same time, biochar can be obtained from the resource utilization of agricultural and forestry wastes. It is not only cheap and environmentally friendly, but also has a high specific surface area and rich pore structure. Therefore, for the purpose of green, economical and efficient removal of microcystins, the present invention combines sodium alginate and carboxymethyl cellulose nanofibers with a crosslinking agent (preferably Ca 2+ ) cross-linked to construct a selective tough hydrogel shell, preferably also equipped with biochar that can enhance the physical adsorption of microcystins and the biological action of functional bacteria, firmly encapsulate the functional degradation bacteria, enhance the physical adsorption-biodegradation synergistic removal of microcystins, and achieve effective treatment of microcystin pollution in lakes and rivers.

[0030] The present invention provides a method for preparing a sodium alginate / nanocellulose bioactive capsule, comprising the following steps:

[0031] S1, dissolving sodium alginate and carboxymethyl cellulose nanofibers in deionized water, and stirring to fully dissolve them;

[0032] S2, adding a functional degradation bacterial suspension, preferably also adding biochar, stirring and mixing, and degassing to obtain a double gel biological mixed solution;

[0033] S3. Through the physical cross-linking method, the double gel mixed solution is dropped into the cross-linking agent solution for cross-linking to obtain a bioactive capsule.

[0034] In some embodiments, the cross-linking agent solution is a CaCl2 solution.

[0035] The embodiment of the present invention also provides a sodium alginate / nanocellulose bioactive capsule prepared by the method.

[0036] The embodiment of the present invention also provides an application of the sodium alginate / nanocellulose bioactive capsule prepared by the method for removing microcystins in water.

[0037] The present invention achieves the selective removal of microcystin by encapsulating functional degradation bacteria in sodium alginate / carboxymethyl cellulose nanofiber double gel, constructs a degradation system resistant to interference from environmental factors, and involves the construction of an interpenetrating polymer network, the assembly of active capsules, and the synergistic removal of microcystin by physical adsorption-biodegradation. Sodium alginate / carboxymethyl cellulose nanofiber double gel bioactive capsules encapsulating functional degradation bacteria are prepared by a physical crosslinking method, and the efficient removal of microcystin in lake and river water bodies is achieved through the synergistic effect of physical adsorption and biodegradation.

[0038] The specific embodiments of the present invention are further described below.

[0039] The present invention aims at the problem of poor removal efficiency of microcystin, and proposes a sodium alginate / nanocellulose composite bioactive capsule and a preparation method and application thereof. Experimental results show that the sodium alginate / nanocellulose composite bioactive capsule can achieve efficient removal of microcystin.

[0040] A method for preparing a sodium alginate / nanocellulose bioactive capsule comprises the following steps:

[0041] Step 1: Cultivation of functional degradation bacteria

[0042] The freeze-dried and preserved microcystin-degrading functional bacteria were activated and revived using LB liquid culture medium, and placed in a shaking incubator for static culture. The revived bacteria were transferred to LB solid culture medium by streaking on a plate, and then the pure bacteria were screened and transferred to liquid culture medium for further expansion. Finally, the cultured bacterial solution was taken out and centrifuged at 7000r / min for 3min. After the functional bacteria were separated, they were re-dispersed and suspended in physiological saline and the OD600 value of the bacterial suspension was controlled to be 2.0.

[0043] Step 2: Encapsulation of bioactive capsules

[0044] 1.0 g of sodium alginate and 0.4 g of carboxymethyl cellulose nanofibers were dissolved in 32 mL of deionized water at 25 ° C, and stirred thoroughly with a magnetic stirrer to fully dissolve. The functional degradation bacteria suspension was added to the sodium alginate / carboxymethyl cellulose nanofiber double gel solution, preferably biochar, and stirred at room temperature for 2 hours to fully mix, and stood for 2 hours to degas, thereby obtaining a double gel biological mixed solution. Through the physical cross-linking method, the double gel mixed solution was dripped into a 1.5% CaCl2 solution at a rate of 100 mL / h using a medical syringe pump for cross-linking for 40 minutes for encapsulation, and the bioactive capsules were obtained and then fully washed with physiological saline.

[0045] The obtained composite material sodium alginate / nanocellulose bioactive capsules were used for the selective removal of microcystin toxins; and the effects of initial pH value and coexisting ions on the removal performance of the composite material and its removal performance in actual lake and river water environments were investigated.

[0046] Embodiment 1:

[0047] The freeze-dried and preserved microcystin-degrading functional bacteria were activated and revived using LB liquid culture medium, and placed in a shaking incubator for static culture (30°C). The revived bacteria were transferred to LB solid culture medium (30°C) by streaking on a plate and cultured for 1 day. After 2 days, pure bacteria were screened and transferred to liquid culture medium for further expansion and culture for 1.5 days. Subsequently, the cultured bacterial solution was taken out and centrifuged at 7000r / min for 3 minutes. After separating the functional bacteria, they were re-dispersed and suspended in physiological saline and the OD600 value of the bacterial suspension was controlled to be 2.0. Activation recovery, streaking on a plate, and transfer inoculation were all carried out in a clean bench.

[0048] 1.0g SA and 0.4g CNF were dissolved in 32mL deionized water at 25°C and stirred for 5h by a magnetic stirrer to fully dissolve. 8mL of the degrading bacteria suspension and 0.06g of biochar were added to the sodium alginate / carboxymethyl cellulose nanofiber double gel solution and stirred for 2h at room temperature to fully mix it and stand for 2h to degas, thereby obtaining a sodium alginate / carboxymethyl cellulose nanofiber-biochar biological mixed solution. Then, the biological mixed solution was dripped into a 1.5% CaCl2 solution at a rate of 100mL / h by a medical syringe pump for cross-linking for 40min, and a sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsule (SA / CNF-BC Bio Capsule) was obtained and then fully washed with saline.

[0049] The capsule combines the biodegradability and biocompatibility of sodium alginate and carboxymethyl cellulose nanofibers, the high specific surface area of ​​biochar to enhance the physical adsorption capacity, and the biodegradation effect of functional degrading bacteria, achieving a synergistic effect of physical adsorption and biodegradation, and can efficiently treat microcystin pollution in lake and river waters.

[0050] Comparative Example 1:

[0051] 1.0g of SA and 0.4g of CNF were dissolved in 32mL of deionized water at 25°C and stirred for 5h by a magnetic stirrer to fully dissolve them. 8mL of saline and 0.06g of biochar were added to the sodium alginate / carboxymethyl cellulose nanofiber double gel solution and stirred for 2h at room temperature to fully mix it and stand for 2h to degas, thereby obtaining a sodium alginate / carboxymethyl cellulose nanofiber-biochar mixed solution. Then, the mixed solution was dripped into a 1.5% CaCl2 solution at a rate of 100mL / h by a medical syringe pump for cross-linking for 40min, and a sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsule (SA / CNF-BC Capsule) was obtained and then fully washed with saline.

[0052] Embodiment 2:

[0053] The freeze-dried and preserved microcystin-degrading functional bacteria were activated and revived using LB liquid culture medium, and placed in a shaking incubator for static culture (30°C). The revived bacteria were transferred to LB solid culture medium (30°C) by streaking on a plate and cultured for 1 day. After 2 days, pure bacteria were screened and transferred to liquid culture medium for further expansion and culture for 1.5 days. Subsequently, the cultured bacterial solution was taken out and centrifuged at 7000r / min for 3 minutes. After separating the functional bacteria, they were re-dispersed and suspended in physiological saline and the OD600 value of the bacterial suspension was controlled to be 2.0. Activation recovery, streaking on a plate, and transfer inoculation were all carried out in a clean bench.

[0054] 1.0g of SA and 0.4g of CNF were dissolved in 32mL of deionized water at 25°C and stirred for 5h by a magnetic stirrer to fully dissolve. 8mL of the degrading bacteria suspension was added to the sodium alginate / carboxymethyl cellulose nanofiber double gel solution and stirred for 2h at room temperature to fully mix it and stand for 2h to degas, thereby obtaining a sodium alginate / carboxymethyl cellulose nanofiber biological mixed solution. The biological mixed solution was then dripped into a 1.5% CaCl2 solution at a rate of 100mL / h by a medical syringe pump for cross-linking for 40min to obtain a sodium alginate / carboxymethyl cellulose nanofiber bioactive capsule (SA / CNF Bio Capsule) and then fully washed with saline.

[0055] Figure 1The removal performance comparison of the composite materials prepared in Examples 1 and 2 of the present invention and Comparative Example 1 is shown. It can be seen from the figure that SA / CNF Bio Capsule and SA / CNF-BC Bio Capsule can remove microcystin to less than 1 μg / L within 24 hours, and SA / CNF-BC Bio Capsule has a higher removal efficiency under the synergistic effect of biochar adsorption and functional degradation bacteria degradation.

[0056] Figure 2 The SEM images of the composite materials prepared in Examples 1 and 2 of the present invention and Comparative Example 1 are shown. It can be seen from the figure that the biochar and the functional degradation bacteria are evenly distributed on the surface of the gel layer. In the SA / CNF-BC Bio Capsule, the functional degradation bacteria are either attached to the gel or to the surface of the biochar, which is beneficial to the capture and degradation of microcystin by the capsule.

[0057] Figure 3 The removal efficiency of microcystin under the influence of coexisting ions of sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsules prepared in Example 1 of the present invention is shown. It can be seen from the figure that in addition to high concentrations of CO3 2- In addition, the other coexisting anions and cations will not have a significant effect on the removal of microcystins, which reflects the excellent anti-ion interference ability of the active capsule.

[0058] Figure 4 The removal efficiency of microcystin at different initial pH values ​​of sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsules and equal amounts of functional degradation bacteria prepared in Example 1 of the present invention is shown. As can be seen from the figure, the gel shell well protects the activity of the functional degradation bacteria inside the capsule, allowing the functional degradation bacteria to maintain efficient degradation of microcystin in an acidic and alkaline environment.

[0059] Figure 5 The removal efficiency of microcystin under different initial pH and natural organic matter coexistence of sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsules prepared in Example 1 of the present invention is shown. It can be seen from the figure that the presence of natural organic matter in different pH environments basically does not interfere with the removal of microcystin, which is related to the selective permeability of the gel shell to natural organic matter.

[0060] Figure 6 The kinetic curve of the degradation of microcystins in actual lake and river water by the sodium alginate / carboxymethyl cellulose nanofiber-biochar bioactive capsule prepared in Example 1 of the present invention is shown. As can be seen from the figure, the active capsule exhibits excellent microcystin degradation effect on actual river and lake water contaminated by microcystin.

[0061] In summary, the present invention proposes a method for preparing and applying an efficient and environmentally friendly sodium alginate / nanocellulose bioactive capsule, which can achieve efficient removal of microcystins in water. By utilizing sodium alginate and carboxymethyl cellulose nanofibers, two biodegradable and biocompatible biomaterials, the present invention constructs a tough and selective hydrogel shell, which enhances its stability and selectivity through physical cross-linking with a cross-linking agent. Preferably, the introduction of biochar provides excellent physical adsorption capacity due to its high specific surface area and rich pore structure. The encapsulation of functional degrading bacteria makes the capsule biologically active and can further remove microcystins through the biodegradation process. The synergistic effect of this physical adsorption and biodegradation greatly improves the removal efficiency and constructs a stable degradation system that can resist interference from environmental factors. The bioactive capsule prepared by the present invention not only improves the removal efficiency of microcystins, but is also suitable for pollution treatment of lakes and rivers, providing an innovative and efficient solution for water environment safety.

[0062] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A method for preparing sodium alginate / nanocellulose bioactive capsules, characterized in that: The steps include: S1, dissolving sodium alginate and carboxymethyl cellulose nanofibers in deionized water, and stirring to fully dissolve them; S2, adding a functional degradation bacterial suspension, preferably also adding biochar, stirring and mixing, and degassing to obtain a double gel biological mixed solution; S3. Through the physical cross-linking method, the double gel mixed solution is dropped into the cross-linking agent solution for cross-linking to obtain a bioactive capsule.

2. The preparation method according to claim 1, characterized in that The cross-linking agent solution is a CaCl2 solution.

3. The preparation method according to claim 2, characterized in that: The concentration of the CaCl2 solution is 1.2%-1.8%, and the cross-linking time is 30-60 minutes.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The method further includes the step of culturing the functional degradation bacteria used in step S2.

5. The preparation method according to claim 4, characterized in that: The culturing of the functional degradation bacteria comprises: using LB liquid culture medium to activate and revive the microcystin degradation functional bacteria preserved by freeze-drying, placing the microcystin degradation functional bacteria in a shaking incubator for static culture, transferring the revived functional bacteria to LB solid culture medium for culture, screening the pure bacteria and transferring them to liquid culture medium for expanded culture; taking out the cultured bacterial liquid, centrifugally separating the functional bacteria, and dispersing and suspending them in physiological saline.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The weight ratio of the sodium alginate to the carboxymethyl cellulose nanofibers is between 2.5:1 and 3.5:

1.

7. The preparation method according to claim 6, characterized in that: The added amount of the biochar is 6%-8% of the weight of the sodium alginate.

8. The preparation method according to any one of claims 5 to 7, characterized in that: The OD600 value of the functional degradation bacteria suspension is 1.9-2.

1.

9. Sodium alginate / nanocellulose bioactive capsules prepared by the method according to any one of claims 1 to 8.

10. Use of the sodium alginate / nanocellulose bioactive capsules prepared by the method according to any one of claims 1 to 8 for removing microcystins in water.

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