Preparation method of environment-friendly organic quaternary ammonium salt modified clay capable of efficiently removing algae

Abstract

The invention belongs to the field of harmful algae bloom prevention and control, and particularly relates to a preparation method of environment-friendly organic quaternary ammonium salt modified clay capable of efficiently removing algae. The preparation method comprises the following steps: carrying out hydroxyl activation treatment on the surface of a raw material clay mineral, adding a silane-containing organic quaternary ammonium salt modifier (Si-QAC) after treatment, and regulating valence bond binding reaction between silane-containing groups in modifier molecules and active sites on the surface of the clay to obtain the organic quaternary ammonium salt modified clay. The preparation method has the advantages that accurate regulation and control and strong bonding of grafting modification of organic quaternary ammonium salt molecules on the surface of clay are realized by utilizing the valence bond action of silyl groups in the organic silicon quaternary ammonium salt molecules and active sites on the surface of the clay, and an efficient and stable algae removal composite material is obtained; a novel method is provided for precisely synthesizing the organic quaternary ammonium salt modified clay with good ecological safety.

Description

Technical Field

[0001] The invention belongs to the field of harmful algal bloom prevention and control, and specifically is a method for preparing environmentally friendly and efficient algae-removing organic quaternary ammonium salt modified clay. Background Art

[0002] Harmful Algal Blooms (HABs), also known as red tides, are an ecological abnormality caused by the explosive proliferation or aggregation of microorganisms in seawater. As a global marine ecological disaster, harmful algal blooms pose a huge threat to offshore ecological security, economic development and human health, and are listed as one of the three major offshore environmental problems today by relevant United Nations environmental organizations. Under the influence of human activities and global changes, the number of algae species causing harmful algal blooms has increased, the number of harmful methods has increased, and the trend of increasing harm continues to rise. According to incomplete statistics, there are more than 2,000 human poisoning incidents caused by red tides worldwide each year, with a mortality rate of 15%. my country is one of the countries with the most serious red tide hazards in the world, with more than 70 red tides occurring each year, resulting in economic losses of up to 30 billion yuan. In order to protect offshore ecological security, economic development and human health, safe and efficient red tide prevention and control measures are urgently needed.

[0003] Modified clay (MC) red tide control technology is the only large-scale red tide emergency treatment method currently used on site at home and abroad. At present, it has been successfully applied in more than 20 sea areas from south to north in my country, becoming an important technical guarantee for the control of harmful red tides in major events, sensitive seas and important economic development areas. In 2017, this technology went abroad for the first time, and then it was exported to the United States, Chile and other countries, becoming a widely recognized method for the control of harmful algal blooms at home and abroad.

[0004] Up to now, a series of modified clays such as inorganic modified clay, organic modified clay, microbial modified clay and composite modified clay have been developed for different application and treatment scenarios. Among them, organic quaternary ammonium salt modified clay (QAC-MC) has the characteristics of low dosage and high algae removal efficiency, and shows good applicability in the fine treatment of aquaculture water. However, the adsorption of ordinary organic quaternary ammonium salt modifiers (QAC) on the clay surface is mainly through physical effects such as electrostatic effect, van der Waals force and hydrophobic effect. Its adsorption stability is poor, and it is easy to cause the modifier to be desorbed from the clay surface, thereby affecting the stability and ecological safety of QAC-MC. Therefore, it is urgent to develop an organic quaternary ammonium salt modification method that can be stably combined with the clay surface and quantitatively controllable, so as to provide a type of modified material with higher stability and better ecological safety for the efficient treatment of harmful algal blooms. Summary of the invention

[0005] In view of the poor stability and unsatisfactory ecological safety of the existing organic quaternary ammonium salt modified clay, the purpose of the present invention is to provide an environmentally friendly and efficient algae removal method for preparing organic quaternary ammonium salt modified clay for harmful algal bloom control.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The invention discloses a method for preparing environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay. The surface of raw clay mineral is subjected to hydroxyl activation treatment, and after the treatment, a silane-containing organic quaternary ammonium salt modifier (Si-QAC) is added. The valence bond reaction between the silane-containing group in the modifier molecule and the active site on the clay surface is regulated to obtain the organic quaternary ammonium salt-modified clay.

[0008] The valence bond reaction between the silane-containing group in the modifier molecule and the active site on the clay surface is achieved by performing a hydroxyl activation treatment on the surface of the clay mineral, mixing the raw clay mineral with the silane-containing organic quaternary ammonium salt modifier (g: mmol) in a ratio of 5: (0.3-30), and reacting the mixture under heating conditions of 40-80° C. for 6-24 hours.

[0009] The silane-containing organic quaternary ammonium salt modifier (Si-QAC) contains a silicon group, an aliphatic hydrocarbon group and a nitrogen-containing group.

[0010] The structural formula of the silane-containing organic quaternary ammonium salt modifier (Si-QAC) is as shown in Formula 1:

[0011]

[0012] In the formula, R can be a C1-C20 alkoxy group or a C1-C20 halogenated alkoxy group; R 1 It can be C1-C20 alkyl, C1-C20 alkoxy, C1-C20 halogenated alkoxy, C1-C20 acyl, C1-C20 alkoxycarbonyl; R 2 can be H, C1-C20 alkyl, C1-C20 alkoxy, - It is an anion.

[0013] Preferably, R is a C1-C4 alkoxy group; R 1 and R 2 is a C1-C6 alkyl group, X - F - , Cl - Br - ,I - Halogen anions.

[0014] The activation treatment of hydroxyl groups on the clay surface refers to treating the clay mineral with acid or alkali, or introducing compounds containing active hydroxyl groups on the clay surface.

[0015] The acid or alkali treatment refers to placing the clay mineral in an acid or alkali solution, shaking and vibrating the solution at room temperature or under heating conditions for more than 1 hour, and then washing the solution with ethanol by centrifugation and drying.

[0016] The acid solution is made of inorganic acid; the alkaline solution is made of one or more of hydroxides, oxides or salts of alkali metals or alkaline earth metals.

[0017] The acid or alkali treatment is to mix the raw material kaolin with an acid or alkali solution in a mass ratio of 1:2 to 1:50 and then react.

[0018] The method of introducing the compound containing active hydroxyl groups on the surface of clay comprises dispersing clay mineral in a mixed solution containing anhydrous ethanol, ammonia water and water, uniformly dispersing the clay mineral by ultrasonication, and then slowly dropping a silicon-based precursor capable of reacting to generate a compound containing active hydroxyl groups into the mixed solution under heating and stirring conditions at 40 to 80° C. until the reaction is complete; wherein the mass ratio of the clay mineral to the silicon-based precursor is 5:1 to 5:50; and the silicon-based precursor is prepared from one or more of silanol, siloxane and silicate, preferably tetraethyl silicate (TEOS).

[0019] The clay minerals are aluminosilicate minerals, such as kaolin, montmorillonite, illite, attapulgite, halloysite, etc., and mixtures of two or more thereof.

[0020] An environmentally friendly and highly efficient algae-removing organic quaternary ammonium salt-modified clay prepared by the method can obtain organic quaternary ammonium salt-modified clay with high stability and good ecological safety.

[0021] An application of the environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay, wherein the organic quaternary ammonium salt-modified clay is used in removing harmful algal blooms in the environment.

[0022] The invention discloses a method for preparing environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay. After the surface of aluminosilicate mineral clay is subjected to hydroxyl activation treatment, an organic quaternary ammonium salt modifier (Si-QAC) containing a silane group is added, and the valence bond reaction between the silane group in the modifier molecule and the active site on the clay surface is regulated to achieve directional anchoring of the modifier on the clay surface, thereby obtaining a quaternary ammonium salt-modified clay material with high stability, good ecological safety and high efficiency in eliminating common harmful algal bloom organisms.

[0023] The advantages and positive effects of the present invention are:

[0024] The advantage of the present invention is that, by utilizing the molecular valence bond effect between the silane group in the Si-QAC molecule and the active site on the clay surface, precise regulation and strong bonding of the grafted modification of the organic quaternary ammonium salt molecules on the clay surface are achieved, thereby obtaining a composite material that not only can efficiently remove algae but also has high stability, thereby providing a new method for the precise synthesis of organic quaternary ammonium salt-modified clay with good ecological safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a comparison chart of the removal efficiency of Heterosigma akashiwo using silane-containing organic quaternary ammonium salt (Si-QAC) modified clay prepared by different surface hydroxyl activation methods provided in Example 1 of the present invention.

[0026] Figure 2 This is a comparison chart of the removal efficiency of Heterosigma akashiwo by Si-QAC modified clays containing different nitrogen-containing head groups provided in Example 2 of the present invention.

[0027] Figure 3 This is a comparison chart of the removal efficiency of Heterosigma akashiwo using Si-QAC modified clays containing different aliphatic hydrocarbon chain lengths provided in Example 3 of the present invention.

[0028] Figure 4 This is a comparison chart of the removal efficiency of modified clay on Heterosigma akashiwo obtained under different tetraethyl silicate (TEOS) addition ratios provided in Example 4 of the present invention.

[0029] Figure 5 This is a comparison chart of the removal efficiency of modified clay for Heterosigma akashiwo obtained under different trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPTAC) addition ratios provided in Example 5 of the present invention.

[0030] Figure 6 This is a comparison chart of the removal effects of different typical red tide algae by the optimized modified clay provided in Example 6 of the present invention.

[0031] Figure 7 This is a comparison chart of the surface potential and removal efficiency of Heterosigma akashiwo of the optimized prepared modified clay provided in Example 6 of the present invention and the common quaternary ammonium salt modified clay after multiple washings. DETAILED DESCRIPTION

[0032] The following specific examples further illustrate the method for preparing an environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay according to the present invention, which will help ordinary technicians in the field to understand the present invention more comprehensively, but will not limit the present invention in any way.

[0033] The modified clay of the present invention is a quaternary ammonium salt modifier (Si-QAC) containing a silane group, after the surface of the aluminosilicate mineral clay is subjected to a hydroxyl activation treatment. The valence bond reaction between the silane group in the modifier molecule and the active site on the clay surface is regulated to achieve directional anchoring of the modifier on the clay surface, thereby obtaining a quaternary ammonium salt modified clay material with high stability, good ecological safety and high efficiency in eliminating common harmful algal bloom organisms.

[0034] After the clay surface is subjected to hydroxyl activation treatment, the present invention adds a silane-containing organic quaternary ammonium salt modifier (Si-QAC), and by regulating the valence bond reaction between the silane group in the molecule and the active site on the clay surface, the directional anchoring of the modifier on the clay surface is achieved, thereby obtaining a class of organic quaternary ammonium salt-modified clay materials with high stability, good ecological safety, and high efficiency in eliminating common harmful algae blooms. The advantage of the present invention is that the valence bond effect between the silane group in the organosilicon quaternary ammonium salt molecule and the active site on the clay surface is utilized to achieve precise regulation and strong bonding of the grafting modification of the organic quaternary ammonium salt molecule on the clay surface, thereby obtaining an efficient and stable algae removal composite material, and providing a new method for accurately synthesizing organic quaternary ammonium salt-modified clay with good ecological safety.

[0035] Example 1

[0036] The mineral raw material used in the method of the present invention is commercially available washed kaolin. The clay is treated by different surface hydroxylation activation methods, and then a silicon-containing organic quaternary ammonium salt modifier (Si-QAC) is added. The valence bond reaction between the silane group in the molecule and the active site on the clay surface is regulated to achieve directional anchoring of the modifier on the clay surface, thereby obtaining organic quaternary ammonium salt modified clay. The specific preparation method is as follows:

[0037] Step 1: Activate the kaolin surface with acid, alkali and covalent grafting of active hydroxyl compounds respectively:

[0038] (1) Acid-activated clay: 10 g of raw kaolin was weighed and placed in 200 ml of a 4 mol / dm 3 The mixture was shaken and reacted for 6 days in a shaking table at room temperature in a hydrochloric acid solution. After that, it was washed by centrifugation three times with an ethanol and water solution in a volume ratio of 1:1, and then dried and crushed for standby use.

[0039] (2) Alkali-activated clay: 10 g of raw kaolin was weighed and placed in 200 ml of a 2 mol / dm 3 In sodium hydroxide solution, shake and vibrate on a shaker at room temperature for 6 days, then centrifuge and wash three times with ethanol and water solution in a volume ratio of 1:1, dry and crush for standby use;

[0040] (3) Covalent grafting of hydroxyl compounds: Weigh 5g of raw kaolin and place it in a three-necked flask with a capacity of 250ml, add 80ml of anhydrous ethanol, 4.6ml of ammonia water and 1.5ml of pure water respectively, and mix them evenly by ultrasonic for 30min. Then add tetraethyl silicate (TEOS) into the pressure-partial funnel at a mass ratio of 5:12 of Kaolin:TEOS, and then add it into the three-necked flask containing the activated kaolin mixture at a rate of 1 drop / s, and keep stirring for 6h at 60℃ for standby use;

[0041] Step 2: Weigh 5g of kaolin, alkali-activated kaolin, and acid-activated kaolin respectively, place them in a three-necked flask with a capacity of 250ml, then add 80ml of anhydrous ethanol and 1.5ml of pure water respectively, and mix them evenly by ultrasonication for 30min. Afterwards, add trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPTAC) into the flask at a ratio of 5:1 between the raw material clay mineral (Kaolin) and TPTAC (g: mmol), and keep stirring and heating at 60°C for 12h. After the reaction is completed, the resulting mixed solution is washed 3 times with anhydrous ethanol at a centrifugal speed of 5000r / min and a centrifugal time of 5min to obtain modified clay materials recorded as modified clay-I, II and III of the present invention (see Figure 1 );

[0042] Step 3: Add a certain amount of trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPTAC) to the product obtained in the above step 1-(3), and then keep stirring and heating at 60°C for 12 hours; wherein the addition ratio of TPTAC is based on the raw material kaolin (Kaolin), and the ratio of Kaolin to TPTAC (g: mmol) is 5:1. After the reaction is completed, the mixed solution is washed three times with anhydrous ethanol at a centrifugal speed of 5000r / min and a centrifugal time of 5min to obtain a modified clay material recorded as modified clay-IV of the present invention.

[0043] Example 2

[0044] The same steps and conditions as those for preparing the modified clay-IV of the present invention in Example 1 are used, except that the type of nitrogen-containing group of Si-QAC added in step 3 is changed. The specific implementation method is as follows:

[0045] Step 1. Weigh 4 portions of 5 g of raw kaolin and place them in a 250 ml three-necked flask, then add 80 ml of anhydrous ethanol, 4.6 ml of ammonia water and 1.5 ml of pure water, and mix them evenly by ultrasonication for 30 minutes, and then place them in a 60°C water bath for heating and stirring.

[0046] Step 2: Weigh the raw materials kaolin and tetraethyl silicate (TEOS) in a mass ratio of 5:12, place the weighed TEOS in a pressure dividing funnel, add it to the three-necked flask containing the kaolin mixture in step 1 at a rate of 1 drop / s, and keep stirring and heating at 60°C for 6h.

[0047] Step 3, select Si-QACs containing different types of nitrogen-containing head groups (primary, secondary, tertiary amines and quaternary ammonium), namely 3-aminopropyltrimethoxysilane (APTES), N-methyl-3-aminopropyltrimethoxysilane (MAPTES), [3-(N,N-dimethylamino)propyl]trimethoxysilane (DAPTES) and trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPTAC);

[0048] The product obtained in step 2 was mixed with the above-mentioned different Si-QACs respectively, and then stirred and heated at 60°C for 12 hours; wherein, the addition ratio of Si-QAC was based on the raw material kaolin (Kaolin), and the ratio of Kaolin to the above-mentioned different Si-QACs (g: mmol) was 5:1.

[0049] Step 4: Wash the mixed solution obtained in step 3 with anhydrous ethanol three times at a centrifugal speed of 5000 r / min for 5 minutes to obtain organic quaternary ammonium salt-modified clay containing different types of nitrogen-containing head groups.

[0050] Example 3

[0051] The same steps and conditions as in Example 2 were followed, except that the chain length of the aliphatic hydrocarbon group of Si-QAC added in step 3 was changed. The specific implementation method was as follows:

[0052] Step 1. Weigh 5 portions of 5 g of raw kaolin and place them in a 250 ml three-necked flask, then add 80 ml of anhydrous ethanol, 4.6 ml of ammonia water and 1.5 ml of pure water, and mix them evenly by ultrasonication for 30 minutes, and then place them in a 60°C water bath for heating and stirring.

[0053] Step 2: Weigh the raw materials kaolin and tetraethyl silicate (TEOS) in a mass ratio of 5:12, place the weighed TEOS in a pressure dividing funnel, add it to the three-necked flask containing the kaolin mixture in step 1 at a rate of 1 drop / s, and keep stirring and heating at 60°C for 6h.

[0054] Step 3: Select Si-QAC with different aliphatic hydrocarbon chain lengths, i.e., two R 2 The substituents are all C1, and the other R 2The substituents are C1, C6, C12, C14, and C18, respectively, i.e., trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPTAC), hexadecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride (TPHDAC), dodecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride (TPDDAC), tetradecyldimethyl(3-trimethoxysilylpropyl)ammonium chloride (TPTDAC), and dimethyloctadecyl[3-trimethoxysilylpropyl]ammonium chloride (TPODAC);

[0055] The product obtained in step 2 was mixed with the above-mentioned different Si-QACs respectively, and then stirred and heated at 60°C for 12 hours; wherein, the addition ratio of Si-QAC was based on the raw material kaolin (Kaolin), and the ratio of Kaolin to the above-mentioned different Si-QACs (g: mmol) was 5:1.

[0056] Step 4: Wash the mixed solution obtained in step 3 with anhydrous ethanol three times at a centrifugal speed of 5000 r / min for 5 minutes to obtain organic quaternary ammonium salt-modified clay containing different aliphatic hydrocarbon chain lengths.

[0057] Example 4

[0058] The same steps and conditions as in Example 3 were used, except that the type of the fixed Si-QAC was trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPTAC), and the addition ratio of tetraethyl silicate (TEOS) in step 2 was changed. The specific implementation method was as follows:

[0059] Step 1: Weigh 6 portions of 5 g of raw kaolin and place them in a 250 ml three-necked flask, then add 80 ml of anhydrous ethanol, 4.6 ml of ammonia water and 1.5 ml of pure water, and mix them evenly by ultrasonication for 30 minutes, and then place them in a 60°C water bath for heating and stirring.

[0060] Step 2: Weigh the raw materials kaolin and tetraethyl silicate (TEOS) according to the mass ratio of 5:3, 5:6, 5:12, 5:24, 5:36, and 5:48, respectively, place the weighed TEOS in a pressure dividing funnel, add it to the three-necked flask containing the kaolin mixture at a rate of 1 drop / s, and keep stirring and heating at 60°C for 6 hours.

[0061] Step 3: The different products obtained in the above step 2 are mixed with a certain proportion of trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPTAC), and then stirred and heated at 60°C for 12 hours; wherein the addition ratio of TPTAC is based on the raw material kaolin (Kaolin), and the ratio of Kaolin to TPTAC (g: mmol) is 5:2.

[0062] Step 4: Wash the mixed solution obtained in step 3 with anhydrous ethanol three times at a centrifugal speed of 5000 r / min for 5 minutes to obtain modified clay prepared under different tetraethyl silicate addition ratios.

[0063] Example 5

[0064] The same steps and conditions as those in Example 4 were used, except that the mass ratio of the raw materials kaolin (Kaolin) to tetraethyl silicate (TEOS) in step 2 was 5:12, and the addition ratio of Si-QAC was changed. The specific implementation method is as follows:

[0065] Step 1. Weigh 6 portions of 5g kaolin and place them in a 250ml three-necked flask, then add 80ml of anhydrous ethanol, 4.6ml of ammonia water and 1.5ml of pure water, and mix them evenly by ultrasonication for 30min, then place them in a 60℃ water bath for heating and stirring.

[0066] Step 2: Weigh the raw materials kaolin and tetraethyl silicate (TEOS) in a mass ratio of 5:12, put the weighed TEOS in a pressure dividing funnel, add it into the three-necked flask containing the kaolin mixture at a rate of 1 drop / s, and keep stirring and heating at 60°C for 6h.

[0067] Step 3, the product obtained in the above step 2 is mixed with different proportions of trimethyl [3- (trimethoxysilyl) propyl] ammonium chloride (TPTAC), and then kept stirring and heating at 60 ° C for 12 hours; wherein, the addition ratio of TPTAC is based on the raw material kaolin (Kaolin), and the ratio of Kaolin to TPTAC (g: mmol) is 5:0.3, 5:0.6, 5:1, 5:2, 5:6, 5:30.

[0068] Step 4: The mixed solution obtained in step 3 was washed three times with anhydrous ethanol at a centrifugal speed of 5000 r / min for 5 minutes to obtain modified clay prepared under different TPTAC addition ratios.

[0069] Example 6

[0070] The same steps and conditions as in Example 5 were followed, except that the ratio of Kaolin to TPTAC (g: mmol) was fixed at 5:2 and the number of centrifugal washes was changed. The specific implementation method is as follows:

[0071] Step 1. Weigh 6 portions of 5g kaolin and place them in a 250ml three-necked flask, then add 80ml of anhydrous ethanol, 4.6ml of ammonia water and 1.5ml of pure water, and mix them evenly by ultrasonication for 30min, then place them in a 60℃ water bath for heating and stirring.

[0072] Step 2: According to the mass ratio of Kaolin:TEOS of 5:12, a certain amount of TEOS was placed in a pressure funnel, and added into the three-necked flask containing the kaolin mixture at a rate of 1 drop / s, and heated at 60°C with stirring for 6 hours.

[0073] Step 3: Mix the product obtained in the above step 2 with a certain proportion of trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPTAC), and then stir and heat at 60°C for 12 hours; wherein the addition ratio of TPTAC is based on the raw material kaolin (Kaolin), and the ratio of Kaolin to TPTAC (g: mmol) is 5:2.

[0074] Step 4: Wash the mixed solution obtained in step 3 with anhydrous ethanol for 3, 4, 5, 6, 7, 8 and 9 times respectively at a centrifugal speed of 5000 r / min for 5 min to obtain modified clay, which is recorded as the optimized modified clay prepared by the present invention.

[0075] Comparative Example 1

[0076] 2.5 g of kaolin and 0.025 g of hexadecyltrimethylammonium chloride were weighed respectively and placed in 80 ml of deionized water. After mixing, the mixture was aged at 60°C for 3 h. Then, the mixture was washed with anhydrous ethanol for 3, 4, 5, 6, 7, 8, and 9 times at a centrifugal speed of 5000 r / min and a centrifugal speed of 5 min to obtain a modified clay material, which was recorded as ordinary quaternary ammonium salt modified clay.

[0077] Application Examples

[0078] The selection and cultivation process of experimental organisms are as follows: The experimental organisms are selected from common harmful algal bloom organisms in my country's coastal waters. According to their cell structure and cell size, the experimental algae species selected are Heterosigma akashiwo (H.akashiwo), Prorocentrum donghaiense (P.donghaiense) and A.anophagefferens. All conventional algae species are preserved in the Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Sciences. The seawater used to cultivate the algae species was taken from the coastal waters of Huangdao District, Qingdao, China. The seawater was filtered using a 0.45μm mixed fiber membrane when it was collected. Afterwards, it was sterilized with high-temperature steam in an autoclave, and L 1 The algae were cultured in the type medium under the conditions of (20±1)°C and light-dark ratio L:D=12h:12h.

[0079] The algae culture used 1 The specific preparation method of the culture medium is as follows: add 1 ml of 75 g / L NaNO 3, 1ml of 5g / L NaH 2 PO 4 ·H 2 O, 1mL of 30g / L Na 2 SiO 3 9H 2 O, 1mL of trace element solution, 0.5mL of f / 2 vitamin solution.

[0080] The algae removal experiment steps are as follows: add seawater to the obtained modified clay material to prepare a 50g / L modified clay suspension, and then take red tide algae in the middle and late exponential growth stages (algae cell density is about 1-2×10 6 cells / L) as the removal target, and put it in a 25mL colorimetric tube. Then, according to the modified clay concentration, a quantitative modified clay suspension was pipetted and added to the colorimetric tube containing the algae solution, and it was inverted and mixed and then left to incubate for 3 hours. After that, the algae solution 5 cm below the liquid surface was pipetted to measure the fluorescence value. The algae removal efficiency of modified clay is calculated as follows:

[0081] Algae removal efficiency (%) = [1-(living fluorescence value of experimental group / living fluorescence value of control group)] × 100%

[0082] 1) The organic quaternary ammonium salt modified clay prepared by different surface hydroxyl activation methods provided in Example 1 was used to remove Heterosigma akashiwo. The results are as follows: Figure 1 As shown. At a concentration of 0.1 g / L, the algae removal effect of using raw material kaolin (Kaolin) alone is poor, only 5.1%. The surface of Kaolin is directly modified with Si-QAC, and the algae removal efficiency of the modified clay-I of the present invention synthesized is 9.7%. The surface of Kaolin is acid or alkali activated and then modified with Si-QAC, and the algae removal efficiencies of the modified clay-II and III of the present invention synthesized are 14.6% and 21.8%, respectively. After the surface of Kaolin is covalently grafted with a silicon-containing hydroxyl compound and then modified with Si-QAC, the algae removal efficiency of the modified clay-IV of the present invention synthesized is 84.1%. This shows that the introduction of active silicon hydroxyl compounds on the clay surface can significantly improve the algae removal efficiency of the modified clay prepared by the present invention. Therefore, the treatment of introducing active silicon hydroxyl compounds on the clay surface is used as the best surface activation method in the method of the present invention.

[0083] 2) The Si-QAC modified clay with different nitrogen-containing head groups provided in Example 2 was used to remove Heterosigma akashiwo. The results are as follows: Figure 2As shown. There are obvious differences in the algae removal efficiency of organic quaternary ammonium salt-modified clays containing different nitrogen-containing groups, and the order of algae removal efficiency is: TPTAC (quaternary ammonium) > APTES (primary amine) > MAPTES (secondary amine) > DAPTES (tertiary amine). Therefore, the best nitrogen-containing head group for preparing organic quaternary ammonium salt-modified clay by the method of the present invention is quaternary ammonium.

[0084] 3) The Si-QAC modified clay with different aliphatic hydrocarbon chain lengths provided in Example 3 was used to remove Heterosigma akashiwo. The results are as follows: Figure 3 As shown. When the two R 2 The substituents are all C1, and the other R 2 When the substituents are C1, C6, C12, C14, and C18, respectively, as the length of the aliphatic hydrocarbon chain increases, the algae removal efficiency of the synthesized organic quaternary ammonium salt modified clay gradually decreases. 2 When the substituents are all C1, the algae removal efficiency of the synthetic modified clay is the highest, which is 84.1%. 2 Trimethyl[3-(trimethoxysilyl)propyl]ammonium chloride (TPTAC) whose substituents are all C1 is the best Si-QAC of the present invention.

[0085] 4) The modified clay obtained under different tetraethyl silicate (TEOS) addition ratios provided in Example 4 was used to remove Heterosigma akashiwo. The results are as follows: Figure 4 As shown. The algae removal efficiency of the organic quaternary ammonium salt modified clay synthesized by the method of the present invention shows a trend of first increasing and then decreasing with the increase of the TEOS addition ratio. When the mass ratio of Kaolin:TEOS is controlled at 5:12, an organic quaternary ammonium salt modified clay with excellent algae removal performance can be obtained. Under this ratio condition, when the modified clay is used at a concentration of 0.1g / L, a removal efficiency of 97% can be achieved for Heterosigma akashiwo.

[0086] 5) The modified clay material obtained under different TPTAC addition ratios provided in Example 5 was used to remove Heterosigma akashiwo. The results are as follows: Figure 5 As shown in the figure, the algae removal efficiency of the synthetic modified clay increases first and then decreases with the increase of the TPTAC addition ratio. When the Kaolin:TPTAC ratio is controlled at 5:1-5:6 (g:mmol), an organic quaternary ammonium salt modified clay with excellent algae removal performance can be obtained. Within this ratio condition range, when the modified clay is used at a concentration of 0.1g / L, the removal efficiency of more than 90% can be achieved for Heterosigma akashiwo.

[0087] 6) The modified clay provided in Example 6 (washed 3 times as an example) was set at different concentrations (i.e., 0.05, 0.1, 0.15, and 0.2 g / L) to perform removal experiments on Heterosigma akashiwo, Prorocentrum donghaiense, and Aureobasidium anophagenum. The results are as follows: Figure 6 As shown in the figure, the organic quaternary ammonium salt modified clay prepared by the present invention can achieve a removal efficiency of more than 90% for Heterosigma akashiwo at a concentration of 0.1 g / L; and for Prorocentrum donghaiense and Aureus antrophaeum, the organic quaternary ammonium salt modified clay prepared by the present invention can also achieve a removal efficiency of more than 90% when the concentration is 0.15 g / L.

[0088] In order to further analyze the stability of the organic quaternary ammonium salt modified clay prepared by the present invention, the optimized modified clay prepared by the present invention provided in Example 6 after multiple washings (i.e., washing with anhydrous ethanol for 3, 4, 5, 6, 7, 8, and 9 times) and the ordinary quaternary ammonium salt modified clay (Comparative Example 1) were compared in terms of removal efficiency and surface potential of Heterosigma akashiwo. The results are shown in FIG. Figure 7 As shown, at a concentration of 0.1 g / L, the algae removal efficiency of common quaternary ammonium salt modified clay after centrifugal washing for 3 times was 38%, and the surface potential was -3.2 mV; and with the increase of the number of centrifugal washings, the algae removal efficiency and surface potential of the common quaternary ammonium salt modified clay gradually decreased. After 9 centrifugal washings, its algae removal efficiency decreased to 10%, and the surface potential decreased to -10.8 mV. However, the algae removal efficiency and surface potential of the modified clay prepared by the present invention did not change significantly with the increase of the number of centrifugal washings, and its algae removal efficiency could be maintained at 90% ± 2%, and the surface potential could be maintained at 9.15 mV ± 0.15 mV.

[0089] This shows that ordinary quaternary ammonium salts have poor adsorption stability on the clay surface and are prone to desorption. The present invention utilizes the valence bond between the silane groups in the organosilicon quaternary ammonium salt molecules and the active sites on the clay surface to achieve strong bonding of the organic quaternary ammonium salt molecules for grafting and modification on the clay surface, thereby obtaining a type of organic quaternary ammonium salt-modified clay material with high stability, good ecological safety, and high efficiency in eliminating common harmful algal blooms.

Claims

1. A method for preparing environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay, characterized in that: The surface of the raw clay mineral is treated with hydroxyl activation, and then a silane-containing organic quaternary ammonium salt modifier (Si-QAC) is added. The valence bond reaction between the silane-containing group in the modifier molecule and the active site on the clay surface is regulated to obtain the organic quaternary ammonium salt modified clay.

2. The method for preparing the environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay according to claim 1, characterized in that: The valence bond reaction between the silane-containing group in the modifier molecule and the active site on the clay surface is achieved by performing a hydroxyl activation treatment on the surface of the clay mineral, mixing the raw clay mineral with the silane-containing organic quaternary ammonium salt modifier (g: mmol) in a ratio of 5: (0.3-30), and reacting the mixture under heating conditions of 40-80° C. for 6-24 hours.

3. The method for preparing the environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay according to claim 1 or 2, characterized in that: The silane-containing organic quaternary ammonium salt modifier (Si-QAC) contains a silicon group, an aliphatic hydrocarbon group and a nitrogen-containing group.

4. The method for preparing the environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay according to claim 3, characterized in that: The structural formula of the silane-containing organic quaternary ammonium salt modifier (Si-QAC) is as shown in general formula 1: In the formula, R can be C1-C20 alkoxy or C1-C20 haloalkoxy; R1 can be C1-C20 alkyl, C1-C20 alkoxy, C1-C20 haloalkoxy, C1-C20 acyl, C1-C20 alkoxycarbonyl; R2 can be H, C1-C20 alkyl, C1-C20 alkoxy, X - It is an anion.

5. The method for preparing the environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay according to claim 1 or 2, characterized in that: The activation treatment of hydroxyl groups on the clay surface refers to treating the clay mineral with acid or alkali, or introducing compounds containing active hydroxyl groups on the clay surface.

6. The method for preparing the environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay according to claim 5, characterized in that: The acid or alkali treatment refers to placing the clay mineral in an acid or alkali solution, shaking and vibrating the solution at room temperature or under heating conditions for more than 1 hour, and then washing the solution with ethanol by centrifugation and drying. The acid solution is made of inorganic acid; the alkaline solution is made of one or more of hydroxides, oxides or salts of alkali metals or alkaline earth metals.

7. The method for preparing the environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay according to claim 5, characterized in that: The method of introducing the compound containing active hydroxyl groups on the surface of clay comprises dispersing clay mineral in a mixed solution containing anhydrous ethanol, ammonia water and water, uniformly dispersing the clay mineral by ultrasonic treatment, and then slowly dropping a silicon-based precursor capable of reacting to generate a compound containing active hydroxyl groups into the mixed solution under heating and stirring conditions at 40 to 80° C. until the reaction is complete; wherein the mass ratio of the clay mineral to the silicon-based precursor is 5:1 to 5:50; and the silicon-based precursor is prepared from one or more of silanol, siloxane and silicate.

8. The method for preparing the environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay according to claim 5, characterized in that: The clay mineral is an aluminosilicate mineral.

9. An environmentally friendly and efficient algae-removing organic quaternary ammonium salt-modified clay prepared by the method of claim 1, characterized in that: The organic quaternary ammonium salt modified clay with high stability and good ecological safety is prepared according to the method of claim 1.

10. An application of the environmentally friendly and efficient algae-removing organic quaternary ammonium salt modified clay according to claim 9, characterized in that: The organic quaternary ammonium salt modified clay is used in removing harmful algal blooms in the environment.

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