A bio-based polyurethane foam loaded with wood vinegar solution that has a killing effect on cyanobacteria

Abstract

The present invention provides a bio-based polyurethane foam with a killing effect on cyanobacteria that carries wood vinegar, belonging to the field of cyanobacteria management and organic waste utilization. The bio-based polyurethane foam includes the following components, and the mass fractions of each component are: 48-50 parts of polyols, 30-35 parts of polyphenyl polymethylene polyisocyanates, 2-3 parts of polyethylene glycol chitosan, 1-1.5 parts of quaternary ammonium salt chitosan, 0.1-0.2 parts of pore openers, 1-2 parts of chain extenders, 1-1.5 parts of chemical foaming agents, 1-2 parts of foam stabilizers, and 0.3-0.5 parts of amine catalysts. Wherein polyethylene glycol chitosan is used as a cross-linking agent, which is modified by polyethylene glycol methyl ether and chitosan. The prepared bio-based polyurethane loaded wood vinegar foam presents hydrophilic, porous and algae-removing characteristics. The bio-based polyurethane loaded wood vinegar foam can efficiently remove cyanobacteria blooms for a long time, and has good biodegradability.

Description

Technical Field

[0001] The present invention relates to the fields of cyanobacteria treatment and organic waste utilization, and particularly relates to a bio-based polyurethane foam loaded with wood vinegar liquid and having a killing effect on cyanobacteria. Background Art

[0002] The eutrophication of lake water bodies causes cyanobacteria to multiply in large numbers from July to October every year, forming a covering layer of dozens of centimeters on the water surface, resulting in the phenomenon of water blooms. The water bloom phenomenon of cyanobacteria will lead to water quality deterioration, block the filter, consume a large amount of dissolved oxygen in the water body, produce secondary metabolites, especially harmful metabolites such as microcystins, which not only bring adverse effects to the water body and aquatic organisms, but also restrict the development of social economy.

[0003] Currently, the common methods for removing cyanobacteria are divided into physical methods, chemical methods and biological methods. Physical methods usually adopt filtration, but often have high costs, time-consuming and laborious; biological methods have slow effects and it is difficult to achieve universality for algae; chemical methods such as coagulation based on iron salts or aluminum salts, although simple and efficient, have serious secondary pollution. Therefore, an efficient and safe method for removing algae needs to be developed urgently. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of existing algae removal methods and effectively utilize the by-product - wood vinegar liquid generated in the production carbon process, which is an environmentally friendly algae removal method.

[0005] The present invention solves the technical problems by adopting the following technical solutions:

[0006] The present invention discloses a preparation method of a bio-based polyurethane foam loaded with wood vinegar liquid and having a killing effect on cyanobacteria, which is characterized in that the steps are as follows:

[0007] (1) By mass, add 1 part of chitosan, 5 parts of polyethylene glycol methyl ether and 25 parts of 1% acetic acid aqueous solution by mass percentage to a reactor, heat up to 60 - 65 °C, start stirring, after reacting for 6 - 8 h, dry at 110 - 130 °C and -0.1 MPa for 1 - 2 h to obtain polyethylene glycolated chitosan;

[0008] (2) Mix polyol, polyethylene glycolated chitosan, quaternary ammonium salt chitosan, chemical blowing agent, foam stabilizer, amine catalyst, cell opener and chain extender, stir at 3000 r / min for 3 - 5 min, then add polyphenyl polymethylene polyisocyanate, stir at a speed of 3000 r / min for 10 - 15 s and pour into a mold for foaming, cure at 60 °C for 2 - 4 h, and then place at room temperature for 24 h to obtain a bio-based polyurethane foam material;

[0009] (3) adding deionized water to dilute the wood vinegar to a concentration of 5%, and then soaking the bio-based polyurethane foam obtained above in 10 mL of 5% wood vinegar for 2-4 h to allow the polyurethane foam to absorb the wood vinegar, thereby obtaining a polyurethane foam loaded with wood vinegar.

[0010] Preferably, the polyurethane foam is prepared from the following main components, and the mass proportions of each component are: 48-50 parts of polyol, 30-35 parts of polyphenyl polymethylene polyisocyanate, 2-3 parts of polyethylene glycol chitosan, 1-2 parts of chain extender, 1-1.5 parts of quaternary ammonium salt chitosan, 1-2 parts of foam stabilizer, 0.3-0.5 parts of amine catalyst, 1-1.5 parts of chemical foaming agent, and 0.1-0.2 parts of cell opener.

[0011] Preferably, the polyol is any one of polylactic acid polyol with a number average molecular weight of 400-600 and polyethylene glycol with a number average molecular weight of 2000-3000, or a mixture of the two.

[0012] Preferably, the structural formula of the PEGylated chitosan is:

[0013]

[0014] where n 1 =10,n 2 =15.

[0015] Preferably, the isocyanate is polyphenylpolymethylene polyisocyanate (PAPI).

[0016] Preferably, the chain extender is any one of dimethylaminopropylamine diisopropyl alcohol (DPA) and N,N-dimethylethanolamine (DMEA) or a mixture of the two.

[0017] Preferably, the amine catalyst is N,N-dimethylcyclohexylamine or triethylenediamine.

[0018] Preferably, the polyurethane chemical foaming agent is deionized water.

[0019] Preferably, the foam stabilizer is AK8805.

[0020] Preferably, the polyurethane cell opener is ZLY-1900.

[0021] Preferably, the composition ratio of the wood vinegar has a certain range, and the wood vinegar contains about 80% to 9% water and about 10% to 20% organic components, wherein the organic components are composed of the following components by mass percentage: 30-50% acetic acid, 5-15% formic acid, 1-5% phenol, 5-15% 2-methoxyphenol, and 5-15% 2-methoxy-4-methylphenol.

[0022] Preferably, the test algal species is Microcystis aeruginosa (M. aeruginosa), purchased from the Institute of Hydrobiology, Chinese Academy of Sciences, with the number FACHB-1319.

[0023] Preferably, the cell density of the Microcystis aeruginosa is 1.42×10 7 cells / L.

[0024] Preferably, a preparation method of a bio-based polyurethane foam loaded with wood vinegar solution and having a killing effect on cyanobacteria is provided, and a bio-based polyurethane foam loaded with wood vinegar solution and having a killing effect on cyanobacteria is prepared.

[0025] The beneficial effects of the present invention are mainly reflected in the following aspects:

[0026] Wood vinegar solution is a by-product generated during the process of biomass carbonization. Organic acids and phenolic substances are the main organic substances in wood vinegar solution, and they are also the main components endowing wood vinegar solution with bactericidal, deodorizing, and antibacterial functions. However, directly adding wood vinegar solution is likely to cause too high a concentration in a local area, polluting the environment. At the same time, after adding wood vinegar solution, its auto-oxidation or photo-degradation will be accelerated under natural conditions, making it unable to continuously inhibit the growth of algae. To overcome this problem, the present invention uses bio-based polylactic acid polyol and polyethylene glycol as soft segments, and prepares hydrophilic polyurethane foam by one-step foaming method with polyphenyl polymethylene polyisocyanate. By regulating the mass ratio of polyethylene glycol to polylactic acid polyol, the foam has high water absorption rate and can adsorb a large amount of wood vinegar solution. At the same time, the introduced tertiary amine groups in the foam combine with acetic acid and phenolic substances in the wood vinegar solution through dynamic covalent bonds, realizing the pH-responsive slow release of the wood vinegar solution, and greatly improving the utilization rate of the wood vinegar solution.

[0027] The surface of cyanobacteria cells is negatively charged. Due to electrostatic repulsion, it can ensure its stable suspension and reproduction in water. Quaternary ammonium chitosan is positively charged and can eliminate the surface electrostatic effect of cyanobacteria cells, thus causing cyanobacteria to flocculate. However, since directly adding chitosan into water cannot recover quaternary ammonium chitosan, the algae removal efficiency is low. To overcome this problem, chitosan can be grafted onto polyol through a chemical reaction. At the same time, quaternized chitosan is added during the reaction of chitosan polyol and polyisocyanate to prepare hydrophilic polyurethane foam, which can increase the ability of polyurethane foam to continuously kill cyanobacteria. Through the synergistic killing of wood vinegar solution and quaternized chitosan in the bio-based polyurethane foam, the generation and proliferation of cyanobacteria in water can be effectively curbed.

[0028] The process of the present invention is simple and easy to implement. The wood vinegar solution used is obtained by condensing the waste gas generated in the carbon production process, with an environmentally friendly source, and provides an effective way for the utilization of organic waste.

[0029] The present invention utilizes the water absorption of polyurethane foam to load wood vinegar in the polyurethane foam, which plays a role of slow release and greatly increases the contact time between wood vinegar and blue algae.

[0030] The tertiary amine groups introduced into the foam utilized in the present invention are combined with acetic acid and phenolic substances in wood vinegar through dynamic covalent bonds, thereby achieving pH-responsive sustained release of wood vinegar, and greatly improving the utilization rate of wood vinegar;

[0031] The invention provides the foam with a long-lasting antibacterial property through chitosan grafting modification and quaternization treatment, and finally realizes effective inhibition of blue algae in water bodies through the synergistic effect of the slow release of wood vinegar and the quaternized chitosan. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 : is a flow chart of the preparation method of the bio-based polyurethane foam of the present invention;

[0033] Figure 2 : is the removal rate of Microcystis aeruginosa in each embodiment and comparative example;

[0034] Figure 3 : Optical photographs of the Microcystis aeruginosa samples in various embodiments and comparative examples at different times;

[0035] Figure 4 : It is a characterization diagram of the speed of releasing wood vinegar from polyurethane foam in each embodiment and comparative example. DETAILED DESCRIPTION

[0036] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied by other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the features in the following embodiments and embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are to describe specific specific embodiments, rather than to limit the scope of protection of the present invention.

[0037] In one embodiment of the present invention, the polyurethane foam is prepared from the following main components, and the mass proportions of each component are: 48-50 parts of polyol, 30-35 parts of polyphenyl polymethylene polyisocyanate, 2-3 parts of polyethylene glycol chitosan, 1-2 parts of chain extender, 1-1.5 parts of quaternary ammonium salt chitosan, 1-2 parts of foam stabilizer, 0.3-0.5 parts of amine catalyst, 1-1.5 parts of chemical foaming agent, and 0.1-0.2 parts of cell opener.

[0038] In an embodiment of the present invention, the polyol is any one or a combination of two of polylactic acid polyol with a number average molecular weight of 400 - 600 and polyethylene glycol with a number average molecular weight of 2000 - 3000. That is, the polyol can be selected from any one of the above-listed types, such as polylactic acid polyol and polyethylene glycol, or the polyol can also be a combination of the two above-listed compositions, where the mass ratio of polylactic acid polyol to polyethylene glycol is 1:3, 1:2, or 1:1. The isocyanate is polyphenyl polymethylene polyisocyanate (PAPI). The chain extender is a mixture of one or two of dimethylaminopropylamine diisopropanol (DPA) and N,N-dimethylethanolamine (DMEA). That is, the chain extender can be selected from any one of the above-listed types, for example, the chain extender is dimethylaminopropylamine diisopropanol or N,N-dimethylethanolamine, or the chain extender can also be a combination of the two above-listed compositions, where the mass ratio of the two is 1:1. The foam stabilizer is AK8805, and the amine catalyst is N,N-dimethylcyclohexylamine or triethylenediamine.

[0039] The algal species used in the experiment was Microcystis aeruginosa, purchased from the Institute of Hydrobiology, Chinese Academy of Sciences, with the number FACHB-1319. After the algal species was obtained, it was cultured with BG-11 medium. The amplification culture ratio was set as algal liquid:BG-11 medium = 1:3. The light intensity was controlled at 2000 - 2100 lx using a photometer, the temperature was (25 ± 0.5) °C, and the light-dark ratio was 12 h:12 h. The cell density was observed with an optical microscope. The cyanobacteria cell density used in this experiment was 1.42×10 7 cells / L.

[0040] Please refer to Figure 1 , a preparation method of a bio-based polyurethane foam loaded with wood vinegar liquid and having a killing effect on cyanobacteria, comprising the following steps:

[0041] S1. By mass, add 1 part of chitosan, 5 parts of polyethylene glycol methyl ether, and 25 parts of 1% acetic acid aqueous solution by mass to a reactor, heat up to 60 - 65 °C, start stirring, and after reacting for 6 - 8 h, dry at 110 - 130 °C and -0.1 MPa for 1 - 2 h to obtain polyethylene glycolated chitosan;

[0042] For example, the temperature for heating up can be any value within the above temperature range, such as 60 °C, 63 °C, or 65 °C, etc.; the stirring time can be any value within the above time range, such as 6 h, 7 h, or 8 h, etc.; the dehydration temperature can be any value within the above temperature range, such as 110 °C, 120 °C, or 130 °C, etc.; the drying time can be any value within the above time range, such as 1 h, 1.5 h, or 2 h, etc.

[0043] S2. Mix the polyol, polyethylene glycol-modified chitosan, quaternary ammonium salt chitosan, chemical foaming agent, foam stabilizer, catalyst, cell-opening agent and chain extender, stir at 3000 r / min for 3 - 5 min, then add polyphenyl polymethylene polyisocyanate, stir at a rotation speed of 3000 r / min for 10 - 15 s, pour into a mold for foaming, cure at 60 °C for 2 - 4 h, and then place at room temperature for 24 h to obtain the bio-based polyurethane foam material;

[0044] For example, the stirring time can be any value within the above time range such as 3 min, 4 min or 5 min, and the curing time can be any value within the above time range such as 2 h, 2.5 h or 4 h.

[0045] Add deionized water to dilute the wood vinegar liquid to a concentration of 5%, then soak the above-obtained bio-based polyurethane foam in 10 mL of 5% wood vinegar liquid for 2 - 4 h to make the polyurethane foam absorb the wood vinegar liquid, and obtain the polyurethane foam loaded with wood vinegar liquid;

[0046] For example, the soaking time can be any value within the above time range such as 2 h, 3 h or 4 h.

[0047] Perform GC - MS detection on the wood vinegar liquid. The undiluted wood vinegar liquid contains 80% to 90% water and 10% to 20% organic components. The organic components by mass percentage are as follows: acetic acid 30 - 50%, formic acid 5 - 15%, phenol 1 - 5%, 2-methoxyphenol 5 - 15%, 2-methoxy-4-methylphenol 5 - 15%.

[0048] The technical solutions of the present invention will be described in detail through several specific examples below. Unless otherwise specified, the raw materials and reagents used in the following examples are all commercially available products, or can be prepared by conventional methods in the art, and the instruments used in the examples can be commercially purchased.

[0049] Example 1

[0050] By mass fraction, add 1 part of chitosan, 5 parts of polyethylene glycol methyl ether and 25 parts of 1% acetic acid aqueous solution to a reactor, heat up to 60 - 65 °C, start stirring, and after reacting for 6 - 8 h, dry at 110 - 130 °C and -0.1 MPa for 1 - 2 h to obtain polyethylene glycol-modified chitosan (PEG-g-CS).

[0051] The raw materials for preparing bio-based polyurethane foam include, by mass, 16 parts of polylactic acid polyol, 32 parts of polyethylene glycol, 35 parts of polyphenyl polymethylene polyisocyanate, 2 parts of polyethylene glycol chitosan, 1 part of quaternary ammonium salt chitosan, 1 part of foam stabilizer AK8805, 0.3 parts of amine catalyst triethylenediamine, 1 part of chemical foaming agent deionized water, 1 part of chain extender dimethylaminopropylamine diisopropanol, and 0.1 part of cell opener ZLY-1900.

[0052] Accurately weighed polyol, quaternary ammonium salt chitosan, polyethylene glycol chitosan, chemical foaming agent, foam stabilizer, amine catalyst, chain extender and pore opener are added to the paper cup in sequence, mixed evenly to obtain component A, put into the paper cup, and control the temperature at 37°C; weighed polyphenyl polymethylene polyisocyanate component B is added and stirred with a stirrer at a high speed of 3000 r / min. When the material turns white, pour the mixture of components A and B into a pre-prepared container, let it stand at room temperature for foaming, take out the obtained polyurethane foam, place it in a constant temperature blast drying oven at 60°C for curing for 2 h, and then leave it at room temperature for 24 h before cutting it into 3×3×1 cm squares.

[0053] Deionized water was added to dilute the wood vinegar to a concentration of 5%. The organic component of 5% wood vinegar was 1%, and the organic components by mass percentage were as follows: acetic acid 50%; formic acid 15%; phenol 5%; 2-methoxyphenol 15%; 2-methoxy-4-methylphenol 15%. The bio-based polyurethane foam obtained above was then immersed in 10 mL of 5% wood vinegar for 2 h to allow the polyurethane foam to absorb the wood vinegar, thereby obtaining a polyurethane foam loaded with wood vinegar.

[0054] Example 2

[0055] By weight, 1 part of chitosan, 5 parts of polyethylene glycol methyl ether and 25 parts of 1% acetic acid aqueous solution were added to the reactor, the temperature was raised to 60-65 ° C, stirring was started, and the reaction was carried out for 6-8 hours. Then, the reaction was dried at 110-130 ° C and -0.1 MPa for 1-2 hours to obtain polyethylene glycol chitosan (PEG-g-CS).

[0056] The raw materials for preparing bio-based polyurethane foam include, by mass, 12.5 parts of polylactic acid polyol, 37.5 parts of polyethylene glycol, 35 parts of polyphenyl polymethylene polyisocyanate, 2 parts of polyethylene glycol chitosan, 1 part of quaternary ammonium salt chitosan, 1 part of foam stabilizer AK8805, 0.3 parts of amine catalyst triethylenediamine, 1 part of chemical foaming agent deionized water, 1 part of chain extender dimethylaminopropylamine diisopropanol, and 0.1 part of cell opener ZLY-1900.

[0057] Accurately weigh polyols, quaternary ammonium salt chitosan, polyethylene glycol chitosan, chemical blowing agent, foam stabilizer, amine catalyst, chain extender and cell opener in sequence, add them into a paper cup, mix evenly to obtain Component A, put it into the paper cup, and control the temperature at 37 °C; add the weighed polyphenyl polymethylene polyisocyanate Component B and stir at a high speed of 3000 r / min with a stirrer. When the material turns white, pour the mixture of Component A and Component B into a pre-prepared container, let it foam at room temperature, take out the obtained polyurethane foam, place it in a constant temperature air blast drying oven at 60 °C for curing for 2 h, and then place it at room temperature for 24 h, and cut it into cubes with a size of 3×3×1 cm.

[0058] Add deionized water to dilute the wood vinegar liquid to a concentration of 5%. The organic components of the 5% wood vinegar liquid are 1%. The organic components by mass percentage are as follows: acetic acid 50%; formic acid 15%; phenol 5%; 2-methoxyphenol 15%; 2-methoxy-4-methylphenol 15%. Then soak the above-obtained bio-based polyurethane foam in 10 mL of 5% wood vinegar liquid for 2 h to make the polyurethane foam absorb the wood vinegar liquid, and obtain the polyurethane foam loaded with wood vinegar liquid.

[0059] Comparative Example 1

[0060] Observe the cell density with an optical microscope. Put 200 mL of algal liquid with a cyanobacteria cell density of 1.42×10 7 cells / L into a beaker and observe for 60 h.

[0061] Comparative Example 2

[0062] Add deionized water to dilute the wood vinegar liquid to a concentration of 5%. The organic components of the 5% wood vinegar liquid are 1%. The organic components by mass percentage are as follows: acetic acid 15%; phenol 5%; formic acid 5%; 2-methoxyphenol 15%; 2-methoxy-4-methylphenol 15%. Observe the cell density with an optical microscope. Put 200 mL of algal liquid with a cyanobacteria cell density of 1.42×10 7 cells / L into a beaker, then add 10 mL of 5% wood vinegar liquid and finally observe for 60 h.

[0063] Comparative Example 3

[0064] The raw materials used in this example were dehydrated. First, add polyols to a reactor equipped with mechanical stirring, place it in an oil bath at 110 °C, and stir for 2 h in an environment with a vacuum degree lower than -0.1 MPa to remove the water in the system.

[0065] The raw materials for preparing bio-based polyurethane foam include, by mass, 50 parts of polylactic acid polyol, 35 parts of polyphenyl polymethylene polyisocyanate, 1 part of foam stabilizer AK8805, 0.3 parts of amine catalyst triethylenediamine, 1 part of chemical foaming agent deionized water, 1 part of chain extender dimethylaminopropylamine diisopropanol, and 0.1 part of cell opener ZLY-1900.

[0066] Accurately weighed polyols, chemical foaming agents, foam stabilizers, catalysts, chain extenders and cell openers were added to the paper cups in sequence, mixed evenly to obtain component A, and placed in the paper cups, and the temperature was controlled at 37°C; weighed polyphenyl polymethylene polyisocyanate component B was added and stirred with a stirrer at a high speed of 3000 r / min. When the material turned white, the mixture of components A and B was poured into a pre-prepared container, and allowed to stand at room temperature for foaming. The obtained polyurethane foam was taken out and placed in a constant temperature blast drying oven for curing for 2 h, and then placed at room temperature for 24 h before being cut into 3×3×1 cm squares.

[0067] Deionized water was added to dilute the wood vinegar to a concentration of 5%. The organic component of 5% wood vinegar was 1%, and the organic components by mass percentage were as follows: acetic acid 50%; formic acid 15%; phenol 5%; 2-methoxyphenol 15%; 2-methoxy-4-methylphenol 15%. The bio-based polyurethane foam obtained above was then immersed in 10 mL of 5% wood vinegar for 2 h to allow the polyurethane foam to absorb the wood vinegar, thereby obtaining a polyurethane foam loaded with wood vinegar.

[0068] Comparative Example 4

[0069] The raw materials used in this example were dehydrated by first adding the polyol into a reactor equipped with a mechanical stirrer, placing it in an oil bath at 110°C, and stirring it for 2 hours in an environment with a vacuum degree of less than -0.1 MPa to remove water from the system.

[0070] The raw materials for preparing the bio-based polyurethane foam include, by weight: 50 parts of polyethylene glycol, 35 parts of polyphenyl polymethylene polyisocyanate, 1 part of foam stabilizer AK8805, 0.3 parts of amine catalyst triethylenediamine, 1 part of chemical foaming agent deionized water, and 0.1 part of cell opener ZLY-1900.

[0071] Accurately weigh polyols, chemical blowing agents, foam stabilizers, catalysts, and cell openers in sequence, add them to a paper cup, mix evenly to obtain Component A, place it in the paper cup, and control the temperature at 37 °C; add the weighed polyphenyl polymethylene polyisocyanate Component B and stir at a high speed of 3000 r / min with a stirrer. When the material turns white, pour the mixture of Component A and Component B into a pre-prepared container, let it foam at room temperature, take out the obtained polyurethane foam, place it in a constant temperature air blast drying oven for curing for 2 h, and then place it at room temperature for 24 h, and cut it into cubes of 3×3×1 cm.

[0072] Add deionized water to dilute the wood vinegar liquid to a concentration of 5%. The organic components of the 5% wood vinegar liquid are 1%. The organic components by mass percentage are as follows: acetic acid 50%; formic acid 15%; phenol 5%; 2-methoxyphenol 15%; 2-methoxy-4-methylphenol 15%. Then immerse the above-mentioned obtained bio-based polyurethane foam in 10 mL of 5% wood vinegar liquid for 2 h to allow the polyurethane foam to absorb the wood vinegar liquid, and obtain the wood vinegar liquid-loaded polyurethane foam.

[0073] Comparative Example 5

[0074] The raw materials used in this example were dehydrated. First, add polyols to a reactor equipped with mechanical stirring, place it in an oil bath at 110 °C, and stir for 2 hours in an environment with a vacuum degree lower than -0.1 MPa to remove the water in the system.

[0075] The raw materials for preparing the bio-based polyurethane foam include, by mass: 25 parts of polylactic acid polyol, 25 parts of polyethylene glycol, 35 parts of polyphenyl polymethylene isocyanate, 1 part of foam stabilizer AK8805, 0.3 part of amine catalyst triethylenediamine, 1 part of chemical blowing agent deionized water, 1 part of chain extender dimethylaminopropylamine diisopropanol, and 0.1 part of cell opener ZLY-1900.

[0076] Accurately weigh polyols, chemical blowing agents, foam stabilizers, amine catalysts, chain extenders, and cell openers in sequence, add them to a paper cup, mix evenly to obtain Component A, place it in the paper cup, and control the temperature at 37 °C; add the weighed polyphenyl polymethylene polyisocyanate Component B and stir at a high speed of 3000 r / min with a stirrer. When the material turns white, pour the mixture of Component A and Component B into a pre-prepared container, let it foam at room temperature, take out the obtained polyurethane foam, place it in a constant temperature air blast drying oven at 60 °C for curing for 2 h, and then place it at room temperature for 24 h, and cut it into cubes of 3×3×1 cm.

[0077] Deionized water was added to dilute the wood vinegar to a concentration of 5%. The organic component of 5% wood vinegar was 1%, and the organic components by mass percentage were as follows: acetic acid 50%; formic acid 15%; phenol 5%; 2-methoxyphenol 15%; 2-methoxy-4-methylphenol 15%. The bio-based polyurethane foam obtained above was then immersed in 10 mL of 5% wood vinegar for 2 h to allow the polyurethane foam to absorb the wood vinegar, thereby obtaining a polyurethane foam loaded with wood vinegar.

[0078] Comparative Example 6

[0079] The raw materials for preparing the bio-based polyurethane foam include, by mass, 16 parts of polylactic acid polyol, 32 parts of polyethylene glycol, 35 parts of polyphenyl polymethylene polyisocyanate, 1 part of quaternary ammonium salt chitosan, 1 part of foam stabilizer AK8805, 0.3 parts of amine catalyst triethylenediamine, 1 part of chemical foaming agent deionized water, and 0.1 part of cell opener ZLY-1900.

[0080] Accurately weighed polyol, quaternary ammonium salt chitosan, chemical foaming agent, foam stabilizer, amine catalyst and pore opening agent were added to the paper cup in sequence, mixed evenly to obtain component A, and placed in the paper cup, and the temperature was controlled at 37°C; weighed polyphenyl polymethylene polyisocyanate component B was added and stirred with a stirrer at a high speed of 3000 r / min. When the material turned white, the mixture of components A and B was poured into a pre-prepared container, and allowed to stand at room temperature for foaming. The obtained polyurethane foam was taken out, placed in a constant temperature blast drying oven at 60°C for curing for 2 h, and then placed at room temperature for 24 h before being cut into 3×3×1 cm squares.

[0081] Deionized water was added to dilute the wood vinegar to a concentration of 5%. The organic component of 5% wood vinegar was 1%, and the organic components by mass percentage were as follows: acetic acid 50%; formic acid 15%; phenol 5%; 2-methoxyphenol 15%; 2-methoxy-4-methylphenol 15%. The bio-based polyurethane foam obtained above was then immersed in 10 mL of 5% wood vinegar for 2 h to allow the polyurethane foam to absorb the wood vinegar, thereby obtaining a polyurethane foam loaded with wood vinegar.

[0082] Comparative Example 7

[0083] The raw materials used in this example were dehydrated by first adding the polyol into a reactor equipped with a mechanical stirrer, placing it in an oil bath at 110°C, and stirring it for 2 hours in an environment with a vacuum degree of less than -0.1 MPa to remove water from the system.

[0084] The raw materials for preparing bio-based polyurethane foam include, by mass, 16 parts of polylactic acid polyol, 32 parts of polyethylene glycol, 35 parts of polyphenyl polymethylene polyisocyanate, 1 part of quaternary ammonium salt chitosan, 1 part of foam stabilizer AK8805, 0.3 parts of amine catalyst triethylenediamine, 1 part of chemical foaming agent deionized water, 1 part of chain extender dimethylaminopropylamine diisopropanol, and 0.1 part of cell opener ZLY-1900.

[0085] Accurately weighed polyol, quaternary ammonium salt chitosan, chemical foaming agent, foam stabilizer, amine catalyst, chain extender and cell opener are added to the paper cup in sequence, mixed evenly to obtain component A, put into the paper cup, and control the temperature at 37°C; weighed polyphenyl polymethylene polyisocyanate component B is added and stirred with a stirrer at a high speed of 3000 r / min. When the material turns white, pour the mixture of components A and B into a pre-prepared container, let it stand at room temperature for foaming, take out the obtained polyurethane foam, place it in a constant temperature blast drying oven at 60°C for curing for 2 h, and then leave it at room temperature for 24 h before cutting it into 3×3×1 cm squares.

[0086] Deionized water was added to dilute the wood vinegar to a concentration of 5%. The organic component of 5% wood vinegar was 1%, and the organic components by mass percentage were as follows: acetic acid 50%; formic acid 15%; phenol 5%; 2-methoxyphenol 15%; 2-methoxy-4-methylphenol 15%. The bio-based polyurethane foam obtained above was then immersed in 10 mL of 5% wood vinegar for 2 h to allow the polyurethane foam to absorb the wood vinegar, thereby obtaining a polyurethane foam loaded with wood vinegar.

[0087] Test Case

[0088] Table 1

[0089] Sample Water absorption rate Degradation rate Algae removal rate Example 1 510% 31% 84% Example 2 670% 40% 92% Comparative example 1 / / 2% Comparative example 2 / / 16% Comparative example 3 80% 43% 3% Comparative example 4 910% 7% 38% Comparative example 5 340% 36% 63% Comparative example 6 470% 30% 70% Comparative example 7 480% 21% 74%

[0090] Water absorption test: The water absorption performance of the polyurethane foams of Examples 1-2 and Comparative Examples 1-7 was tested. The foam sheets were cut into 3×3×1 cm squares, dried in an oven for 24 h, and initially weighed Y I Then, it was immersed in 120 ml of distilled water. After equilibration at 37 °C for 48 h, the sample was removed from the water, suspended for 10 s to allow free drainage, excess water was absorbed with paper, and then weighed again to obtain Y W The water absorption rate Y is shown in formula (1):

[0091] Y=(Y W -Y I ) / Y I ×100% (1);

[0092] In formula (1): Y = water absorption; Y I= Initial mass of the foam; Y W = Mass after water absorption. The results are shown in Table 1. It can be seen from the test results that the water absorption performance of the bio-based polyurethane foams prepared in Examples 1-2 becomes better with the increase in the content of polyethylene glycol. In Comparative Example 3, since it only contains polylactic acid polyol, its hydrophilicity is poor, while in Comparative Example 4, it only contains polyethylene glycol and has good hydrophilicity and the highest water absorption rate. The water absorption performance of the bio-based polyurethane foams prepared in Comparative Examples 5-7 becomes better with the increase in the content of polyethylene glycol.

[0093] Algae removal rate test: The algae removal performance of Examples 1-2 and Comparative Examples 1-7 was tested. The polyurethane foam loaded with wood vinegar was placed in a beaker with 200 mL and a blue algae cell density of 1.42×10 7 cells / L for 60 h. First, 5 mL of the treated algal liquid was taken from the beaker and centrifuged at 4000 r / min for 10 min to remove the supernatant. Secondly, the microalgae were resuspended in 90% acetone (5 mL), and then stored in the dark at 4 °C for 24 h. Finally, the suspension was centrifuged at 4000 r / min for 15 min. The supernatant was collected for the determination of chlorophyll a concentration. The absorbance of the acetone solution at 630, 645, 663, and 750 nm was recorded using a UV-visible spectrophotometer. The chlorophyll a concentration (mg / L) was calculated by the following equation:

[0094] C = [11.64×(OD 663 - OD 750 ) - 2.16×(OD 645 - OD 750 ) + 0.10×(OD 630 - OD 750 )]×V 1 / V (2);

[0095] In Equation (2): C: Chlorophyll a concentration, mg / L; OD: Absorbance at each wavelength; V 1 : Volume of the acetone-based extract, mL; V: Sample volume, mL.

[0096] The algae removal efficiency W is shown in Equation (3):

[0097] W = (1 - C t / C 0 ) × 100% (3);

[0098] In Equation (3): W = Algae removal rate; C t = Chlorophyll a concentration of the treated algal liquid; C 0 = Initial chlorophyll a concentration of the algal liquid.

[0099] The algae removal results are shown in Table 1 and Figure 2, it can be seen from the test results that the algae removal rates of the bio-based polyurethane foams loaded with slow-release wood vinegar prepared in Examples 1 and 2 are significantly higher than those of Comparative Examples 1-4. In Examples 1 and 2, due to the presence of quaternary ammonium chitosan and polyethylene glycolated chitosan, and the slow release rate of the wood vinegar from the foams, the algae removal efficiency is high. In Comparative Example 2, wood vinegar was directly added, resulting in low algae removal efficiency; in Comparative Example 3, only polylactic acid polyol was contained, with poor hydrophilicity, low wood vinegar release efficiency, and no polyethylene glycolated chitosan and quaternary ammonium chitosan; in Comparative Example 4, polyethylene glycol was contained but no dimethylaminopropylamine diisopropanol chain extender, resulting in fast wood vinegar release and no polyethylene glycolated chitosan and quaternary ammonium chitosan; in Comparative Example 5, the absence of polyethylene glycolated chitosan and quaternary ammonium chitosan led to low algae removal efficiency. In Comparative Example 6, the algae removal efficiency was lower than that of Example 1 because it did not contain polyethylene glycolated chitosan.

[0100] Degradation rate test: The degradation performance of the polyurethanes of Examples 1-2 and Comparative Examples 1-7 was tested. The dried polyurethane foam was cut into a shape of 1 cm×1 cm×0.5 cm and weighed (W 0 ), then immersed in SBF (15 ml) respectively and placed in an incubator at 37 °C with shaking (120 r / min) for one week. Then the foam was transferred to a vacuum drying oven at 37 °C and dried for 72 hours, and then weighed (W T ). The test lasted for five cycles. The degradation rate (W%) is shown in Equation (4):

[0101] W%=(W 0 -W T ) / W 0 ×100% (4);

[0102] In Equation (4): W% = degradation rate; W 0 = initial mass; W T = mass of the foam after degradation.

[0103] The results are shown in Table 1. It can be seen from the test results that the algae removal rates of the bio-based polyurethane foams loaded with slow-release wood vinegar prepared in Examples 1-2 are significantly higher than those of Comparative Example 4. Because Comparative Example 4 only contains polyethylene glycol and no bio-based polyol, the degradation rates of Examples 1 and 2 are higher than those of Comparative Examples 6 and 7 because they contain polyethylene glycolated chitosan, which promotes their degradation. The reason for the relatively high degradation rate of Comparative Example 3 is that it only contains polylactic acid polyol, so the degradation rate is relatively high.

[0104] Slow release rate test: Deionized water with the content of wood vinegar diluted to 0.1% was added to a beaker. Then the polyurethane foam adsorbed with wood vinegar was placed in the beaker, and the ultraviolet-visible spectrophotometer was used to measure the change in the absorbance of phenolic substances in the water at 275 nm at intervals of 6 h to characterize the release rate of wood vinegar from the foam. The results are as Figure 4As shown. It can be seen from the figure that the rate of wood vinegar release from Examples 1 to 2 is slower than that of Comparative Example 4 because Comparative Example 4 only uses polyethylene glycol as the polyol, and its excellent hydrophilicity allows for rapid exchange with the external water body. At the same time, it does not contain dimethylaminopropylamine diisopropanol, and the acidic and phenolic substances in the wood vinegar cannot achieve pH-responsive slow release of the wood vinegar. The release rate of Example 2 is faster than that of Comparative Example 5 and Comparative Example 7 because it has a high content of polyethylene glycol and good hydrophilicity. The release rate of Comparative Example 6 is fast because it does not contain dimethylaminopropylamine diisopropanol, and the acidic and phenolic substances in the wood vinegar cannot achieve pH-responsive slow release of the wood vinegar.

[0105] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A bio-based polyurethane foam loaded with wood vinegar having a killing effect on blue algae, characterized in that: Bio-based polyurethane foam includes the following components, and the mass fraction of each component is: 48-50 parts of polyol; 30-35 parts of polyphenyl polymethylene polyisocyanate; 2-3 parts of PEGylated chitosan; 1-2 parts of chain extender; 1-1.5 parts of quaternary ammonium salt chitosan; 1-2 parts of foam stabilizer; 0.3-0.5 parts of amine catalyst; 1-1.5 parts of chemical foaming agent; 0.1-0.2 parts of pore opening agent; Wherein, the polyol is a mixture of polylactic acid polyol with a number average molecular weight of 400-600 and polyethylene glycol with a number average molecular weight of 2000-3000; The bio-based polyurethane foam is soaked in wood vinegar to obtain the wood vinegar-loaded bio-based polyurethane foam which has a killing effect on blue algae.

2. The bio-based polyurethane foam loaded with wood vinegar having a killing effect on blue algae according to claim 1, characterized in that: The structural formula of the PEGylated chitosan is: ； Where n1=10, n2=15.

3. The bio-based polyurethane foam loaded with wood vinegar having a killing effect on blue algae according to claim 1, characterized in that: The chain extender is any one of dimethylaminopropylamine, diisopropyl alcohol and N,N-dimethylethanolamine or a mixture of the two.

4. The bio-based polyurethane foam loaded with wood vinegar having a killing effect on blue algae according to claim 1, characterized in that: The amine catalyst is N,N-dimethylcyclohexylamine or triethylenediamine.

5. The bio-based polyurethane foam loaded with wood vinegar having a killing effect on blue algae according to claim 1, characterized in that: The wood vinegar contains 80% to 90% of water and 10% to 20% of organic components; the organic components are composed of the following by mass percentage: 30-50% of acetic acid, 5-15% of formic acid, 1-5% of phenol, 5-15% of 2-methoxyphenol, and 5-15% of 2-methoxy-4-methylphenol.

6. A method for preparing a bio-based polyurethane foam loaded with wood vinegar and having a killing effect on blue algae, characterized in that: The method is applied to prepare a bio-based polyurethane foam loaded with wood vinegar and having a killing effect on blue algae as described in any one of claims 1 to 5, comprising the following steps: Step (1), by weight, adding 1 part of chitosan, 5 parts of polyethylene glycol methyl ether and 25 parts of 1% acetic acid aqueous solution into a reactor, heating to 60-65°C, stirring, reacting for 6-8 hours, and drying at 110-130°C and -0.1MPa for 1-2 hours to obtain polyethylene glycol chitosan; Step (2), after mixing polyethylene glycol, polylactic acid polyol, polyethylene glycol chitosan, quaternary ammonium salt chitosan, chemical foaming agent, foam stabilizer, amine catalyst, cell opener and chain extender, stirring at 3000 r / min for 3-5 min, adding polyphenyl polymethylene polyisocyanate, stirring at 3000 r / min for 10-15 s, pouring into a mold for foaming, curing at 60°C for 2-4 h, and then leaving at room temperature for 24 h to obtain a bio-based polyurethane foam material; Step (3), adding deionized water to dilute the wood vinegar to a concentration of 5%, and soaking the bio-based polyurethane foam obtained in step (2) in 10 mL of 5% wood vinegar for 2-4 h to allow the polyurethane foam to absorb the wood vinegar, thereby obtaining a polyurethane foam loaded with wood vinegar.

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