Preparation method of quaternary ammonium salt type composite algaecide

Abstract

The invention discloses a quaternary ammonium salt type composite algaecide for preventing and controlling harmful algae in a reservoir water body and a preparation method of the quaternary ammonium salt type composite algaecide. According to the preparation method, gemini quaternary ammonium salt (dichlorinated 1, 1 '-([1, 1'-biphenyl]-4, 4 '-diyl) bis (N-benzyl-N, N-dimethyl ammonium), dichlorinated N, N'-([1, 1 '-biphenyl]-4, 4'-diyl bis (methylene)) bis (N, N '-(1, 1'-biphenyl]-4, 4 '-diyl bis (methylene)) is utilized to react with N, N'-(1, 1 '-biphenyl]-4, 4'-diyl) bis (N-benzyl-N, N- According to the present invention, N, N-dimethylpyridine-4-amine), dodecyl dimethyl benzyl ammonium bromide, dodecyl dimethyl benzyl ammonium chloride, hexadecyl dimethyl benzyl ammonium chloride, benzalkonium chloride, isothiazolinone and derivatives thereof are respectively subjected to synergistic algal inhibition, and are used for inhibiting common algal blooms in reservoir water. The quaternary ammonium salt type composite algaecide has a higher removal rate on harmful algae (such as microcystis aeruginosa) in a water body of a reservoir, can effectively control water bloom caused by the harmful algae in the water body, and is simple to prepare and good in algae removal effect.

Description

Technical Field

[0001] The present application relates to the field of chemistry, and to a quaternary ammonium salt type composite algaecide, and a preparation method and application thereof. Background Art

[0003] At present, the methods for eliminating microcystis blooms mainly include physical methods, biological methods and chemical methods. In terms of physical control, for algal blooms formed by unicellular algae, water diversion, water exchange, filtration and other measures are often used. There are also studies exploring the use of centrifugation, vibration and other means to separate or collect algal blooms from water bodies. For algal blooms formed by filamentous algae, they are usually treated by artificial salvage. Although this method is environmentally friendly and economical, it is extremely time-consuming and laborious when facing large-scale reproduction in water bodies. In addition, there are also studies trying to use ultrasound, electromagnetic fields and radiation technologies to control algal blooms, but due to their high application costs, promotion faces certain difficulties. In terms of chemical control, chemical methods, as the main means in practical applications, have the advantages of time saving, convenience and significant effects. It mainly uses heavy metal salts, herbicides and other substances to achieve algae removal effects through oxidation, heavy metal toxicity, flocculation and other effects. Especially in emergency situations in response to water blooms, chemical algae removal is favored because of its low dosage and quick effect. However, this method is also prone to secondary pollution of water bodies and ecological risks. For example, copper sulfate, which was used in the early days to control algae pollution, is now banned because of its high toxicity and serious harm to aquatic life.

[0004] Quaternary ammonium compounds (QACs), as a type of cationic surfactant, have a good inhibitory effect on microorganisms. They mainly destroy the cell membrane by changing the bilayer structure of phospholipids in the cell membrane, leading to the loss of substances in the cell, thereby killing the microorganisms. As algaecides, QACs have the advantages of good stability, low toxicity, non-irritation, and reliable action, and are particularly effective in removing bacteria and algae under alkaline conditions. Compared with ordinary surfactants, QACs have lower critical micelle concentrations, higher surface activity, and better wetting, solubilization, foaming and anti-algae activities. Since the cell surface of cyanobacteria represented by Microcystis is negatively charged, light in weight and has a special structure (there are air sacs in the cell), and most algae are phototactic and often float on the water surface during the day, the use of cationic surfactants to reduce the surface and interfacial tension between solids, liquids, and gases has become the preferred method for algae removal. Summary of the invention

[0005] The present invention aims to overcome the shortcomings of the existing technology and provide a method for preparing an effective quaternary ammonium salt type composite algaecide. The present invention utilizes gemini quaternary ammonium salt (dichlorinated 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium), dichlorinated N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine)) to respectively cooperate with quaternary ammonium salts such as dodecyldimethylbenzylammonium bromide, dodecyldimethylbenzylammonium chloride, hexadecyldimethylbenzylammonium chloride, benzalkonium chloride, isothiazolinone and its derivatives to inhibit algae, and is applied to inhibit common algae blooms in reservoir water bodies. The quaternary ammonium salt type composite algaecide has a higher removal rate for harmful algae (such as Microcystis aeruginosa) in reservoir water bodies, can effectively control the water bloom caused by harmful algae in water bodies, and the quaternary ammonium salt type composite algaecide is simple to prepare and has a good algae removal effect.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] The raw material components of the quaternary ammonium salt composite algaecide provided by the invention are: gemini quaternary ammonium salt (1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium dichloride), N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride), dodecyldimethylbenzylammonium bromide, dodecyldimethylbenzylammonium chloride, hexadecyldimethylbenzylammonium chloride, benzalkonium chloride and isothiazolinone.

[0008] In some embodiments of the present invention, the quaternary ammonium salt composite algaecide includes the following components in parts by mass: 1 part of 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride, 1 part of dodecyldimethylbenzylammonium bromide and 0.1 to 0.2 parts of isothiazolinone.

[0009] In some embodiments of the present invention, the quaternary ammonium salt composite algaecide includes the following components in parts by mass: 1 part of 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride, 1 part of dodecyldimethylbenzyl ammonium chloride and 0.1 to 0.2 parts of isothiazolinone.

[0010] In some embodiments of the present invention, the quaternary ammonium salt composite algaecide includes the following components in parts by mass: 1 part of 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride, 1 part of hexadecyldimethylbenzyl ammonium chloride and 0.1 to 0.2 parts of isothiazolinone.

[0011] In some embodiments of the present invention, the quaternary ammonium salt composite algaecide includes the following components in parts by mass: 1 part of 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride, 1 part of benzalkonium chloride and 0.1 to 0.2 parts of isothiazolinone.

[0012] In some embodiments of the present invention, the quaternary ammonium salt composite algaecide includes the following components in parts by mass: 1 part of N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine)) dichloride, 1 part of dodecyldimethylbenzyl ammonium bromide and 0.1 to 0.2 parts of isothiazolinone.

[0013] In some embodiments of the present invention, the quaternary ammonium salt composite algaecide includes the following components in parts by mass: 1 part of N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride, 1 part of dodecyldimethylbenzyl ammonium chloride and 0.1 to 0.2 parts of isothiazolinone.

[0014] In some embodiments of the present invention, the quaternary ammonium salt composite algaecide includes the following components in parts by mass: 1 part of N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride, 1 part of hexadecyldimethylbenzyl ammonium chloride and 0.1 to 0.2 parts of isothiazolinone.

[0015] In some embodiments of the present invention, the quaternary ammonium salt composite algaecide includes the following components in parts by mass: 1 part of N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride, 1 part of benzalkonium chloride and 0.1 to 0.2 parts of isothiazolinone.

[0016] In one embodiment of the present invention, the preparation method of the quaternary ammonium salt type composite algaecide comprises: mixing a gemini quaternary ammonium salt and a conventional algaecide, and dissolving them in water to obtain the quaternary ammonium salt type composite algaecide.

[0017] In an embodiment of the present invention, the final concentration of the quaternary ammonium salt composite algaecide in the algae-containing water body is 4 to 10 mg / L.

[0018] In an embodiment of the present invention, the treatment time of the quaternary ammonium salt type composite algaecide is 24 to 96 hours.

[0019] In an embodiment of the present invention, the test method is OD680, and the degree of algae removal in the water body is determined by the change in absorbance before and after.

[0020] In an embodiment of the present invention, the algae are harmful cyanobacteria, including but not limited to Microcystis aeruginosa.

[0021] Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant advantages:

[0022] 1. The present invention adopts a chemical control method, utilizing the algae-inhibiting properties of quaternary ammonium salts and isothiazolinones to inhibit the formation of algal blooms in water bodies.

[0023] 2. The quaternary ammonium salt type composite algaecide prepared by the present invention has a higher removal rate for harmful algae (such as Microcystis aeruginosa, etc.) in aquaculture water, and can effectively control the bloom caused by harmful algae in water bodies, and the preparation process of the quaternary ammonium salt type composite algaecide is simple and the cost is low;

[0024] 3. The quaternary ammonium salt composite algaecide prepared by the present invention can overcome the problems of toxic effects and drug resistance caused by high concentration of a single drug. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the algae removal effect of Example 1.

[0026] Figure 2 This is the algae removal effect of Example 2.

[0027] Figure 3 This is the algae removal effect of Example 3.

[0028] Figure 4 This is the algae removal effect of Example 4. Example

[0029] Unless otherwise indicated, implied from the context, or customary in the prior art, all parts and percentages in this application are based on weight, and the test and characterization methods used are all current as of the filing date of this application. Where applicable, the contents of any patent, patent application or publication referred to in this application are fully incorporated herein by reference, and their equivalent patent families are also incorporated by reference, especially the definitions of synthesis techniques, product and processing designs, polymers, comonomers, initiators or catalysts disclosed in these documents in the art. If the definition of a specific term disclosed in the prior art is inconsistent with any definition provided in this application, the definition of the term provided in this application shall prevail.

[0030] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solution of the present application. Unless otherwise specified, the reagents and raw materials used can be purchased through commercial channels. The experimental methods in the following examples that do not specify specific conditions are selected according to conventional methods and conditions, or according to the product specifications.

[0031] The materials and reagents used in this example, except for the gemini quaternary ammonium salt (1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium dichloride), N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride and 1,4-butanediyl-3,3'-bis-1-vinylpyridine dibromide), which are homemade compounds in this laboratory, all other substances are materials and reagents obtained from commercial sources.

[0032] Microcystis aeruginosa (FACHB-905) and BG-11 culture medium were provided by the Institute of Hydrobiology, Chinese Academy of Sciences. Gemini quaternary ammonium salts (1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium dichloride), N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine dichloride), 1,4-butanediyl-3,3'-bis-1-vinylpyridinium dibromide) were prepared in our laboratory. Dodecyldimethylbenzylammonium bromide and benzalkonium chloride were purchased from Shanghai Titan Technology Co., Ltd.

[0033] Microcystis aeruginosa was cultured in a light incubator using BG11 medium at a light intensity of 2000 lx, a light-dark ratio of 12h:12h, and a temperature of 25°C. Before the experiment, Microcystis aeruginosa was pre-cultured to ensure the biological activity and synchronous growth of the experimental algae. 100 mL of algae solution in the early exponential growth stage was taken from each group and divided into 250 mL transparent conical bottles for the experiment.

[0034] Example 1

[0035] In this embodiment, the preparation method of the quaternary ammonium salt type composite algaecide is as follows: 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride and dodecyldimethylbenzylammonium bromide are mixed in a mass ratio of 1:1, dissolved in ultrapure water, and prepared into a quaternary ammonium salt type composite algaecide with a concentration of 4 mg / L, 8 mg / L, and 10 mg / L in the water body, respectively.

[0036] Example 2

[0037] In this embodiment, the preparation method of the quaternary ammonium salt type composite algaecide is as follows: 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride and benzalkonium chloride are mixed in a mass ratio of 1:1, dissolved in ultrapure water, and prepared into a quaternary ammonium salt type composite algaecide with a concentration of 4 mg / L, 8 mg / L, and 10 mg / L in the water body, respectively.

[0038] Example 3

[0039] In this embodiment, the preparation method of the quaternary ammonium salt type composite algaecide is as follows: N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride and dodecyldimethylbenzyl ammonium bromide are mixed in a mass ratio of 1:1, dissolved in ultrapure water, and prepared into a quaternary ammonium salt type composite algaecide with a concentration of 4 mg / L, 8 mg / L, and 10 mg / L in the water body, respectively.

[0040] Example 4

[0041] In this embodiment, the preparation method of the quaternary ammonium salt type composite algaecide is as follows: N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridine-4-amine) dichloride and benzalkonium chloride are mixed in a mass ratio of 1:1, dissolved in ultrapure water, and prepared into a quaternary ammonium salt type composite algaecide with a concentration of 4 mg / L, 8 mg / L, and 10 mg / L in the water body, respectively.

[0042] Comparative Example

[0043] Compared with the above examples, sterile ultrapure water.

[0044] Experimental test analysis:

[0045] The algae removal effects of Examples 1-4 are as follows: Figure 1-4 As shown in Tables 1-4. The results show that all quaternary ammonium salt composite algaecides have excellent algaecide effects on Microcystis aeruginosa. Among them, the quaternary ammonium salt composite algaecide prepared by mixing N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride and dodecyldimethylbenzyl ammonium bromide in a mass ratio of 1:1 has the best algaecide effect. When the algaecide concentration in the water body is 4 mg / L, the removal rate of Microcystis aeruginosa reaches 88.35% within 24 hours. With the increase of algaecide concentration and algaecide time, the algaecide effect is enhanced.

[0046] Table 1 Algae removal rate of quaternary ammonium salt composite algaecide (1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium dichloride) and dodecyl dimethylbenzylammonium bromide)

[0047]

[0048] Table 2 Algae removal rate of quaternary ammonium salt composite algaecide (1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium dichloride) and benzalkonium chloride)

[0049]

[0050] Table 3 Algae removal rate of quaternary ammonium salt composite algaecide (dichloro N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) and dodecyl dimethylbenzyl ammonium bromide)

[0051]

[0052]

[0053] Table 4 Algae removal rate of quaternary ammonium salt composite algaecide (dichloro N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) and benzalkonium chloride)

[0054]

[0055] In summary, the present invention utilizes the gemini quaternary ammonium salt algaecide to synergistically inhibit algae with dodecyl dimethyl benzyl ammonium bromide, dodecyl dimethyl benzyl ammonium chloride, hexadecyl dimethyl benzyl ammonium chloride, benzalkonium chloride, isothiazolinone and its derivatives, and is applied to inhibit common algal blooms in reservoir water bodies. The quaternary ammonium salt type composite algaecide has a higher removal rate for harmful algae (such as Microcystis aeruginosa) in reservoir water bodies in a shorter time, can effectively control the water bloom caused by harmful algae, and the quaternary ammonium salt type composite algaecide has mild synthesis conditions, simple operation and good algae removal effect.

[0056] Next, the preparation method of the gemini quaternary ammonium salt algaecide will be described.

[0057] Example 5

[0058] In this embodiment, the preparation method of biphenyl dichlorobenzyl quaternary ammonium salt (dichloro 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) (LBBA)) comprises the following steps:

[0059]

[0060] Biphenyl dichlorobenzyl benzyl quaternary ammonium salt synthesis route 1

[0061] Biphenyl dichlorobenzyl, dimethylbenzylamine and dichloromethane solvent were charged into a three-necked flask with a stirring bar and a condenser at a feed ratio of 1:1.5, and reacted at 40°C for 12 hours. After the reaction, a large amount of white solid was precipitated. The white solid was added with petroleum ether to make a pulp, filtered, and vacuum dried to obtain product 1.

[0062] Example 6

[0063] This embodiment is basically the same as the above embodiment, with the following features:

[0064] In this embodiment, the preparation method of biphenyl dichlorobenzyl quaternary ammonium salt (dichloro N, N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N, N-dimethylpyridin-4-amine) (LBBD)) comprises the following steps:

[0065]

[0066] Biphenyl dichlorobenzyl benzyl quaternary ammonium salt synthesis route 2

[0067] Biphenyl dichlorobenzyl and dimethylaminopyridine with a feed ratio of 1:1.5 and solvent dichloromethane were placed in a three-necked flask with a stirrer and a condenser, and reacted at 40°C for 12 hours. After the reaction, a large amount of white solid was precipitated. The white solid was added with petroleum ether to make a pulp, filtered, and vacuum dried to obtain product 2.

[0068] Experimental test analysis:

[0069] The NMR results of the synthesized gemini quaternary ammonium salt are analyzed as follows:

[0070] Example 1: The results of H NMR analysis of biphenyl dichlorobenzyl benzyl quaternary ammonium salt (LBBA) are as follows: LBBA: 1H NMR (600MHz, Deuterium Oxide) δ7.78~7.72 (m, 4H), 7.58~7.53 (m, 4H), 7.52~7.46 (m, 4H), 7.46~7.42 (m, 6H), 4.49 (dd, J=11.6, 2.0Hz, 8H), 3.11~2.53 (m, 12H).

[0071] δ = 7.78 ~ 7.72ppm are the four hydrogens on the side of the biphenyl group close to each other; δ = 7.58 ~ 7.53ppm are the four hydrogens on the benzyl benzene ring close to the quaternary ammonium group; δ = 7.52 ~ 7.46ppm are the four hydrogens on the biphenyl group close to the quaternary ammonium group; δ = 7.46 ~ 7.42ppm are the remaining six hydrogens on the benzyl benzene ring; δ = 4.49ppm are the eight hydrogens on the methylene group directly connected to the quaternary ammonium group; δ = 3.11 ~ 2.53ppm are the twelve hydrogens on the four methyl groups directly connected to the quaternary ammonium group. The nuclear magnetic resonance results are consistent with the expected structure, and the above results can prove that biphenyl dichlorobenzyl benzyl quaternary ammonium salt has been successfully synthesized.

[0072] Example 2: The results of H NMR analysis of biphenyl dichlorobenzylpyridinium quaternary ammonium salt (LBBD) are as follows: LBBD: 1H NMR (600MHz, Deuterium Oxide) δ7.99~7.75 (m, 4H), 7.34 (d, J=11.0Hz, 4H), 7.28~7.18 (m, 4H), 6.69~6.55 (m, 4H), 5.11~5.04 (m, 4H), 3.02~2.91 (m, 12H).

[0073] δ = 7.99 ~ 7.75ppm are four hydrogen atoms close to the N atom on the pyridine ring; δ = 7.34ppm are four hydrogen atoms close to the quaternary ammonium group on the pyridine ring; δ = 7.28 ~ 7.18ppm are four hydrogen atoms close to each other on the biphenyl group; δ = 6.69 ~ 6.55ppm are four hydrogen atoms close to the quaternary ammonium group on the biphenyl group; δ = 5.11 ~ 5.04ppm are four hydrogen atoms on the methylene group directly connected to the quaternary ammonium group; δ = 3.02 ~ 2.91ppm are twelve hydrogen atoms on the four methyl groups directly connected to the quaternary ammonium group. The nuclear magnetic resonance results are consistent with the expected structure, and the above results can prove that the biphenyl dichlorobenzyl pyridine quaternary ammonium salt has been successfully synthesized.

[0074] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention of the present invention. Any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention should be equivalent replacement methods. As long as they meet the purpose of the invention of the present invention and do not deviate from the technical principles and inventive concepts of the present invention, they belong to the protection scope of the present invention.

Claims

1. A quaternary ammonium salt type composite algaecide, characterized in that: The invention is prepared from the following raw materials: a gemini quaternary ammonium salt and a traditional algaecide; the gemini quaternary ammonium salt comprises a gemini biphenyl dichlorobenzyl quaternary ammonium salt, and the gemini biphenyl dichlorobenzyl quaternary ammonium salt comprises N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethyldodeca / tetradec / hexadecyl-1-ammonium dichloride; 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium dichloride; N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride; N1,N4-didodeca / tetradec / hexadecyl-N1,N1,N4,N4-tetramethylbutane-1,4-diammonium dibromide; N 1 , N 4 -Dibenzyl-N 1 , N 1 , N 4 , N 4 -tetramethylbutane-1,4-diammonium; and N-dibromide 1 , N 1 , N 4 , N 4 -Tetramethyl-N 1 , N 4 - one or more of di(pyridin-4-yl)butane-1,4-diammonium; the traditional algaecide comprises one or more of dodecyldimethylbenzylammonium bromide, dodecyldimethylbenzylammonium chloride, hexadecyldimethylbenzylammonium chloride, benzalkonium chloride and isothiazolinone and its derivatives.

2. The quaternary ammonium salt composite algaecide according to claim 1, characterized in that: The quaternary ammonium salt composite algaecide comprises the following components in parts by mass: 1 part of 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride, 1 part of dodecyldimethylbenzylammonium bromide and 0.1-0.2 parts of isothiazolinone; Preferably, the quaternary ammonium salt composite algaecide comprises the following components in parts by mass: 1 part of 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride, 1 part of dodecyldimethylbenzyl ammonium chloride and 0.1-0.2 parts of isothiazolinone; Preferably, the quaternary ammonium salt composite algaecide comprises the following components in parts by mass: 1 part of 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride, 1 part of hexadecyldimethylbenzyl ammonium chloride and 0.1-0.2 parts of isothiazolinone; Preferably, the quaternary ammonium salt composite algaecide comprises the following components in parts by mass: 1 part of 1,1'-([1,1'-biphenyl]-4,4'-diyl)bis(N-benzyl-N,N-dimethylmethylammonium) dichloride, 1 part of benzalkonium chloride and 0.1-0.2 parts of isothiazolinone; Preferably, the quaternary ammonium salt composite algaecide comprises the following components in parts by mass: 1 part of N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine)) dichloride, 1 part of dodecyldimethylbenzyl ammonium bromide and 0.1-0.2 parts of isothiazolinone.

3. The preparation of the quaternary ammonium salt composite algaecide according to claim 1, characterized in that The quaternary ammonium salt composite algaecide comprises the following components in parts by mass: 1 part of N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride, 1 part of dodecyldimethylbenzyl ammonium chloride and 0.1-0.2 parts of isothiazolinone.

4. The quaternary ammonium salt composite algaecide according to claim 1, characterized in that: The quaternary ammonium salt composite algaecide comprises the following components in parts by mass: 1 part of N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride, 1 part of hexadecyldimethylbenzyl ammonium chloride and 0.1-0.2 parts of isothiazolinone.

5. The quaternary ammonium salt composite algaecide according to claim 1, characterized in that: The quaternary ammonium salt composite algaecide comprises the following components in parts by mass: 1 part of N,N'-([1,1'-biphenyl]-4,4'-diylbis(methylene))bis(N,N-dimethylpyridin-4-amine) dichloride, 1 part of benzalkonium chloride and 0.1-0.2 parts of isothiazolinone.

6. The method for preparing the quaternary ammonium salt composite algaecide according to any one of claims 1 to 5, characterized in that: The method comprises: mixing a gemini quaternary ammonium salt and a conventional algaecide, and dissolving them in water to obtain the quaternary ammonium salt type composite algaecide.

7. Use of the quaternary ammonium salt type composite algaecide described in claims 1 to 5 in algae removal or algae bloom control.

8. A method for removing algae from water, characterized in that: The method comprises the step of adding the quaternary ammonium salt composite algaecide according to any one of claims 1 to 5 to water containing algae for treatment.

9. The method according to claim 8, characterized in that The final concentration of the quaternary ammonium salt composite algaecide in the water to be treated is 4-10 mg / L.

10. The method according to any one of claims 8 to 9, characterized in that: The method determines the degree of algae removal in water by using the OD680 method.

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