Long-acting slow-release microcapsule water purifying agent as well as preparation method and application thereof

Abstract

The invention relates to the field of environmental remediation materials and slow release, and discloses a long-acting slow-release microcapsule water purifying agent and a preparation method and application thereof.The microcapsule water purifying agent is prepared from core materials of co-immobilized microbial inoculum pellets and Fe < 3 + >-biochar compounds and shell materials of chitosan-humic acid composite materials, the preparation method comprises the following steps: mixing co-immobilized microbial agent pellets with a Fe < 3 + >-charcoal compound, and forming a three-dimensional communicated pore channel structure through a freeze-drying technology to obtain a core material; dispersing the core material in a chitosan-humic acid composite material to form a water-phase emulsion, dropwise adding a chloroform solution containing Tween 80 into a water bath at 40 DEG C to form a W / O type emulsion, adding a genipin cross-linking agent, and completing interfacial polymerization under ultrasonic assistance to obtain a core-shell material; and carrying out ethanol gradient dehydration and supercritical drying on the core-shell material to prepare the microcapsule water purifying agent with high stability and long action period.

Description

Technical Field

[0001] The present invention belongs to the field of environmental restoration materials and sustained-release technology, and specifically relates to a long-acting sustained-release microcapsule water purifier and a preparation method and application thereof. Background Art

[0002] Existing river and lake water purification agents (such as microbial agents and denitrification and phosphorus removal agents) generally have problems such as uncontrollable release rate, susceptibility to decomposition and inactivation by environmental factors (pH, water flow erosion), and the need for frequent addition. These problems result in low agent utilization rate (less than 30%), high cost, and easy to cause secondary pollution.

[0003] Traditional microcapsule technology mostly uses a single wall material (such as sodium alginate), which has defects such as low encapsulation rate (≤60%) and short sustained-release period (<7 days), making it difficult to adapt to the long-term management needs of complex river and lake environments.

[0004] In addition, existing river and lake water purification agents (such as flocculants, adsorbents, microbial preparations, etc.) have the following technical bottlenecks: ① Short action time: Traditional agents are directly exposed to the water environment and are easily affected by water erosion, light decomposition or biodegradation, resulting in an effective action time of less than 48 hours; ② Poor environmental adaptability: The release rate of the agent is difficult to match the dynamic concentration of water pollutants, which can easily lead to excessive release in the early stage and cause ecological risks, or insufficient concentration in the later stage affecting the purification effect; ③ Functional loss: Active ingredients (such as nano iron powder, enzyme preparations) are easily oxidized and ineffective during storage and transportation, and require low-temperature storage, which increases costs.

[0005] At the same time, existing microencapsulation technology applications in the water treatment field are mostly focused on single functional materials (such as coated phosphorus removal fillers), lacking a systematic solution for complex water purification agent systems. Therefore, there is an urgent need to develop a water purifier that combines enhanced stability with long-term sustained release. Summary of the Invention

[0006] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a long-acting sustained-release microcapsule water purifier and its preparation method and application, and to improve the stability of the water purifier and extend the action period through microencapsulation technology.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] A long-lasting and sustained-release microcapsule water purifier, comprising a core material and a shell material, wherein the core material comprises: co-immobilized bacterial agent beads and Fe 3 +-biochar composite; the shell material is a chitosan-humic acid composite material;

[0009] The preparation method of the co-immobilized bacterial agent pellets comprises the following steps:

[0010] A. Bacterial activation: Nitrosomonas sp. and aerobic Pseudomonas sp. were cultured in liquid culture medium until the logarithmic phase, the ammonia nitrogen concentration was 200-250 mg / L, and the bacterial solution concentration reached 1×10 8 CFU / mL;

[0011] B. Co-immobilization step:

[0012] ① First embedding: Mix the aerobic Pseudomonas precipitate with 40-45g / L sodium alginate solution, add 15-20g / L calcium chloride solution and cross-link for 4-6h to form initial pellets;

[0013] ② Second embedding: Mix the Nitrosomonas precipitate with sodium alginate, add the initial pellets, and then drop 15-20 g / L calcium chloride solution for cross-linking for 4-6 hours to obtain co-immobilized bacterial pellets;

[0014] The Fe 3 The preparation method of the +-biochar composite comprises the following steps: mixing peanut shells with ferric nitrate, pyrolyzing them at 500-550℃ with oxygen limitation for 2-3h, and obtaining magnetic Fe 3 +-biochar composite;

[0015] The preparation method of the chitosan-humic acid composite material comprises the following steps:

[0016] ① Chitosan solution: dissolve chitosan in 1-3% acetic acid solution to prepare a 2 wt% chitosan solution;

[0017] ② Humic acid pretreatment: extracted from river and lake sediments, passed through a 100-mesh sieve and mixed with chitosan solution in a volume ratio of 1:3 to form a uniform chitosan-humic acid composite material.

[0018] Preferably, the particle size of the co-immobilized bacterial agent pellets is 0.3 to 0.5 cm.

[0019] Preferably, the mass ratio of the peanut shells to the ferric nitrate is 5:1.

[0020] Preferably, the co-immobilized bacterial agent pellets and Fe 3 The mass ratio of the +-biochar composite was 3:2.

[0021] Preferably, the Fe 3 +-Specific surface area of biochar composite ≥ 400m 2 / g, pore volume ≥ 0.2cm 3 / g,Fe 3 +Loading capacity ≥15mg / g.

[0022] Preferably, the core material is doped with graphene quantum dots, and the weight percentage of the graphene quantum dots is 0.5-1 wt%.

[0023] Preferably, the chitosan has a deacetylation degree of 90%.

[0024] A method for preparing a long-acting sustained-release microcapsule water purifier comprises the following steps:

[0025] S1. Core construction: Co-immobilized bacterial pellets and Fe 3 +-biochar composites were mixed and freeze-dried to form a three-dimensional interconnected pore structure, with the porosity adjusted to 55±5% to obtain the core material;

[0026] S2. Shell coating: ① Disperse the core material in the chitosan-humic acid composite material to form an aqueous emulsion; ② Add a chloroform solution containing Tween 80 dropwise in a 40°C water bath to form a W / O emulsion; ③ Add 0.1-0.5 mol / L genipin crosslinker and complete interfacial polymerization under ultrasound assistance for 1-2 hours to obtain a core-shell material;

[0027] S3. Post-treatment: ① Gradient dehydration: The core-shell material is dehydrated with 30%, 50%, 70%, and 90% ethanol in a gradient manner for 10 minutes each, and finally dehydrated twice with 100% ethanol, each time for 10 to 20 minutes; ② Supercritical drying: Dry in supercritical CO2 fluid for 2 to 3 hours at a pressure of 6 to 9 MPa and a temperature of 38 to 45°C to obtain a long-acting sustained-release microcapsule water purifier.

[0028] Preferably, the particle size of the microcapsule water purifier is 300-500 μm.

[0029] The invention discloses an application of a long-acting slow-release microcapsule water purifier, wherein the long-acting slow-release microcapsule water purifier is applied to water purification or deep treatment of eutrophic rivers and lakes.

[0030] Beneficial effects of the present invention:

[0031] The present invention adopts a core-shell structure to prepare a long-acting slow-release microcapsule water purifier, wherein the core is loaded with a composite water purification active ingredient nitrifying bacteria-denitrifying bacteria co-immobilized bacteria agent and a phosphorus-locking agent Fe3+-biochar complex, Fe 3 +-Biochar composites fix phosphorus through electrostatic adsorption and release Fe under anaerobic conditions 2 + Promote denitrification, form a "adsorption-biodegradation" coupling mechanism, and use the freeze-drying technology to utilize the co-immobilized bacterial pellets and Fe 3+-Biochar composite forms three-dimensional interconnected channels with porosity controlled in the range of 45-55%. The outer shell is composed of pH-responsive chitosan-humic acid composite membrane to achieve adaptive release control of water quality. When the pH of the water body is greater than 7 (eutrophication characteristics), the chitosan-humic acid shell swells and accelerates the release of nitrifying bacteria and denitrifying bacteria. When the pH of the water body is less than 6.5, the chitosan-humic acid shell dissolves and the release rate increases by 4-6 times. Under neutral conditions (pH=7-8), it maintains a slow-release state with a release rate of less than 20% / day. When the water temperature rises (>25℃, algae active period), the graphene quantum dots incorporated into the inner core accelerate pore expansion and achieve enhanced release in the high temperature period.

[0032] The microcapsule water purifier prepared by the present invention has an embedding rate of ≥90%, the sustained-release period in flowing water bodies is extended to 30-45 days, the utilization rate of the water purifier is increased to more than 75%, and the chitosan, humic acid, etc. used are natural degradable materials, without the risk of microplastic residues, and the degradation products can promote the mineralization of organic matter in the bottom mud. In addition, pilot tests in eutrophic rivers show that the total nitrogen and total phosphorus removal rates can reach 82% and 76%, which are significantly improved compared with traditional agents (45% and 50%). The frequency of agent addition is reduced from once a week to once a month, and the comprehensive operation and maintenance costs are greatly reduced. Moreover, after running for 72 hours in a simulated flowing water body (flow rate of 0.2 m / s), the microcapsule structure integrity rate is ≥90%, achieving the dual goals of long-term sustained release and ecological safety of the water purifier, and is suitable for water purification or in-depth treatment of eutrophic rivers and lakes. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0034] Example 1 A method for preparing co-immobilized bacterial agent pellets comprises the following steps:

[0035] A. Bacterial activation: Nitrosomonas sp. and aerobic Pseudomonas sp. were cultured in liquid culture medium until the logarithmic phase, the ammonia nitrogen concentration was 250 mg / L, and the bacterial liquid concentration reached 1×10 8 CFU / mL;

[0036] B. Co-immobilization step:

[0037] ① First embedding: aerobic Pseudomonas sediment was mixed with 45g / L sodium alginate solution, and 20g / L calcium chloride solution was added dropwise for cross-linking for 6h to form initial pellets;

[0038] ② Second embedding: The Nitrosomonas precipitate was mixed with 45 g / L sodium alginate solution, and after adding the initial pellets, 20 g / L calcium chloride solution was dripped into the pellets for cross-linking for 5 hours to obtain co-immobilized bacterial pellets with a particle size of 0.3 cm.

[0039] Example 2 A Fe 3 The preparation method of the +-biochar composite comprises the following steps: mixing peanut shells and ferric nitrate in a mass ratio of 5:1, pyrolyzing them at 550 ° C with oxygen limitation for 2 h, and obtaining magnetic Fe 3 +-Biochar composite.

[0040] Example 3 A method for preparing a chitosan-humic acid composite material comprises the following steps:

[0041] ① Chitosan solution: Chitosan (90% deacetylation) was dissolved in 1% acetic acid solution to prepare a 2 wt% chitosan solution;

[0042] ② Humic acid pretreatment: extracted from river and lake sediments, passed through a 100-mesh sieve and mixed with chitosan solution in a volume ratio of 1:3 to form a uniform chitosan-humic acid composite material.

[0043] Example 4 A method for preparing a long-acting sustained-release microcapsule water purifier comprises the following steps:

[0044] S1. Core construction: The co-immobilized bacterial pellets prepared in Example 1 and the Fe 3 The +-biochar composite was mixed in a mass ratio of 3:2, and a three-dimensional interconnected pore structure was formed by freeze-drying technology. The porosity was adjusted to 51% to obtain the core material;

[0045] S2, shell coating: ① disperse the core material in the chitosan-humic acid composite material prepared in Example 3 to form an aqueous emulsion; ② add a chloroform solution containing Tween 80 dropwise in a 40°C water bath to form a W / O type emulsion; ③ add 0.2 mol / L genipin crosslinker and complete interfacial polymerization under ultrasound assistance for 2 h to obtain a core-shell material;

[0046] S3. Post-treatment: ① Gradient dehydration: The core-shell material was dehydrated with 30%, 50%, 70%, and 90% ethanol in a gradient manner for 10 minutes each, and finally dehydrated with 100% ethanol twice, each time for 15 minutes; ② Supercritical drying: Drying in supercritical CO2 fluid for 2 hours at a pressure of 8 MPa and a temperature of 40°C to obtain a long-acting sustained-release microcapsule water purifier.

[0047] Example 5 A method for preparing a long-acting sustained-release microcapsule water purifier comprises the following steps:

[0048] S1. Core construction: The co-immobilized bacterial pellets prepared in Example 1 and the Fe3 The +-biochar composite was mixed in a mass ratio of 3:2, and a three-dimensional interconnected pore structure was formed by freeze-drying technology. The porosity was adjusted to 55% to obtain the core material;

[0049] S2, shell coating: ① disperse the core material in the chitosan-humic acid composite material prepared in Example 3 to form an aqueous emulsion; ② add a chloroform solution containing Tween 80 dropwise in a 40°C water bath to form a W / O type emulsion; ③ add 0.4 mol / L genipin crosslinker and complete interfacial polymerization under ultrasound assistance for 1 h to obtain a core-shell material;

[0050] S3. Post-treatment: ① Gradient dehydration: The core-shell material was dehydrated with 30%, 50%, 70%, and 90% ethanol in a gradient manner for 10 minutes each, and finally dehydrated with 100% ethanol twice, each time for 15 minutes; ② Supercritical drying: Drying in supercritical CO2 fluid for 2 hours at a pressure of 8 MPa and a temperature of 40°C to obtain a long-acting sustained-release microcapsule water purifier.

[0051] Example 6 A method for preparing a long-acting sustained-release microcapsule water purifier comprises the following steps:

[0052] S1. Core construction: The co-immobilized bacterial pellets prepared in Example 1 and the Fe 3 The +-biochar composite was mixed in a mass ratio of 3:2, and a three-dimensional interconnected pore structure was formed by freeze-drying technology. The porosity was adjusted to 58% to obtain the core material;

[0053] S2, shell coating: ① the core material was dispersed in the chitosan-humic acid composite material prepared in Example 3 to form an aqueous emulsion; ② a chloroform solution containing Tween 80 was added dropwise in a 40°C water bath to form a W / O type emulsion; ③ 0.5 mol / L genipin crosslinker was added and interfacial polymerization was completed under ultrasound assistance for a reaction time of 1.5 h to obtain a core-shell material;

[0054] S3. Post-treatment: ① Gradient dehydration: The core-shell material was dehydrated with 30%, 50%, 70%, and 90% ethanol in a gradient manner for 10 minutes each, and finally dehydrated with 100% ethanol twice, each time for 15 minutes; ② Supercritical drying: Drying in supercritical CO2 fluid for 2 hours at a pressure of 8 MPa and a temperature of 40°C to obtain a long-acting sustained-release microcapsule water purifier.

[0055] Example 7 A method for preparing a long-acting sustained-release microcapsule water purifier comprises the following steps:

[0056] S1, core construction: the co-immobilized bacterial agent beads prepared in Example 1 and the Fe 3+-Biochar composite and graphene quantum dots were mixed in a mass ratio of 3:2:0.05, and a three-dimensional interconnected pore structure was formed by freeze-drying technology. The porosity was adjusted to 58% to obtain the core material;

[0057] S2, shell coating: ① the core material was dispersed in the chitosan-humic acid composite material prepared in Example 3 to form an aqueous emulsion; ② a chloroform solution containing Tween 80 was added dropwise in a 40°C water bath to form a W / O type emulsion; ③ 0.5 mol / L genipin crosslinker was added and interfacial polymerization was completed under ultrasound assistance for a reaction time of 1.5 h to obtain a core-shell material;

[0058] S3. Post-treatment: ① Gradient dehydration: The core-shell material was dehydrated with 30%, 50%, 70%, and 90% ethanol in a gradient manner for 10 minutes each, and finally dehydrated with 100% ethanol twice, each time for 15 minutes; ② Supercritical drying: Drying in supercritical CO2 fluid for 2 hours at a pressure of 8 MPa and a temperature of 40°C to obtain a long-acting sustained-release microcapsule water purifier.

[0059] Performance testing

[0060] The microcapsule water purifiers prepared in Examples 4-7 were subjected to performance testing:

[0061] ① Stability test: After running in simulated flowing water (flow rate 0.2m / s) for 72h, the microcapsule structure integrity rate is ≥90%.

[0062] ② Long-term stability: The microcapsule embedding rate is ≥90%, the sustained-release period in flowing water is extended to 30-45 days, and the utilization rate of the water purifier is increased to more than 75%.

[0063] ③ Embedding efficiency: The bacterial distribution was observed by laser confocal microscopy, and the bacterial embedding rate was ≥85%.

[0064] ④Sustained-release performance: The dialysis method was used to simulate the water environment to measure the cumulative release of phosphorus within 30 days. The initial release rate was <15%, and the cumulative release rate within 30 days was >85%.

[0065] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0066] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention, and such changes and modifications fall within the scope of the invention as claimed.

Claims

1. A long-acting sustained-release microcapsule water purifier, characterized in that: It includes a core material and a shell material, wherein the core material includes: co-immobilized bacterial agent beads and Fe 3+ -biochar composite; the shell material is a chitosan-humic acid composite material; The preparation method of the co-immobilized bacterial agent pellets comprises the following steps: A. Bacterial activation: Nitrosomonas sp. and aerobic Pseudomonas sp. were cultured in liquid culture medium until the logarithmic phase, the ammonia nitrogen concentration was 200-250 mg / L, and the bacterial solution concentration reached 1×10 8 CFU / mL; B. Co-immobilization step: ① First embedding: Mix the aerobic Pseudomonas precipitate with 40-45g / L sodium alginate solution, add 15-20g / L calcium chloride solution and cross-link for 4-6h to form initial pellets; ② Second embedding: Mix the Nitrosomonas precipitate with sodium alginate, add the initial pellets, and then drop 15-20 g / L calcium chloride solution for cross-linking for 4-6 hours to obtain co-immobilized bacterial pellets; The Fe 3+ The preparation method of the biochar composite comprises the following steps: mixing peanut shells with ferric nitrate, pyrolyzing them at 500-550℃ with oxygen limitation for 2-3h, and obtaining magnetic Fe 3+ - Biochar composites; The preparation method of the chitosan-humic acid composite material comprises the following steps: ① Chitosan solution: dissolve chitosan in 1-3% acetic acid solution to prepare a 2 wt% chitosan solution; ② Humic acid pretreatment: extracted from river and lake sediments, passed through a 100-mesh sieve and mixed with chitosan solution in a volume ratio of 1:3 to form a uniform chitosan-humic acid composite material.

2. The long-acting sustained-release microcapsule water purifier according to claim 1, characterized in that: The particle size of the co-immobilized bacterial agent pellets is 0.3 to 0.5 cm.

3. The long-acting sustained-release microcapsule water purifier according to claim 1, characterized in that: The mass ratio of the peanut shells to the ferric nitrate is 5:

1.

4. The long-acting sustained-release microcapsule water purifier according to claim 1, characterized in that: The co-immobilized bacterial agent beads and Fe 3+ -Biochar composite has a mass ratio of 3:

2.

5. The long-acting sustained-release microcapsule water purifier according to claim 1, characterized in that: The Fe 3+ - Specific surface area of biochar composite ≥ 400m 2 / g, pore volume ≥ 0.2cm 3 / g,Fe 3+ Loading capacity ≥15mg / g.

6. The long-acting sustained-release microcapsule water purifier according to claim 1, characterized in that: The core material is doped with graphene quantum dots, and the weight percentage of the graphene quantum dots is 0.5-1 wt%.

7. The long-acting sustained-release microcapsule water purifier according to claim 1, characterized in that: The chitosan has a deacetylation degree of 90%.

8. The method for preparing the long-acting sustained-release microcapsule water purifier according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Core construction: Co-immobilized bacterial pellets and Fe 3+ -Biochar composites were mixed and freeze-dried to form a three-dimensional interconnected pore structure with a porosity controlled to 55±5% to obtain the core material; S2. Shell coating: ① Disperse the core material in the chitosan-humic acid composite material to form an aqueous emulsion; ② Add a chloroform solution containing Tween 80 dropwise in a 40°C water bath to form a W / O emulsion; ③ Add 0.1-0.5 mol / L genipin crosslinker and complete interfacial polymerization under ultrasound assistance for 1-2 hours to obtain a core-shell material; S3. Post-treatment: ① Gradient dehydration: The core-shell material is dehydrated with 30%, 50%, 70%, and 90% ethanol in a gradient manner for 10 minutes each, and finally dehydrated twice with 100% ethanol, each time for 10 to 20 minutes; ② Supercritical drying: Dry in supercritical CO2 fluid for 2 to 3 hours at a pressure of 6 to 9 MPa and a temperature of 38 to 45°C to obtain a long-acting sustained-release microcapsule water purifier.

9. The method for preparing the long-acting sustained-release microcapsule water purifier according to claim 8, characterized in that: The particle size of the microcapsule water purifier is 300-500 μm.

10. The use of the long-acting sustained-release microcapsule water purifier according to claim 1, characterized in that: The long-acting slow-release microcapsule water purifier is used for water purification or deep treatment of eutrophic rivers and lakes.