Modified kaolin algistat as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of water environment-friendly materials, and particularly relates to a modified kaolin algistat as well as a preparation method and application thereof. The modified kaolin algistat provided by the invention is obtained by modifying kaolin by adopting chitosan quaternary ammonium salt and an allelopathic agent, and more specifically, the algistat is obtained by carrying out ultrasonic treatment on the kaolin at 80-100 DEG C by adopting the chitosan quaternary ammonium salt and linoleic acid. The method has the beneficial effects that the algistat obtained by adopting the method disclosed by the invention has a remarkable algal inhibition effect, and experimental results show that the algistat can prevent secondary outbreak of blue-green algae in water for a relatively long time.

Description

Technical Field

[0001] The invention belongs to the technical field of water environmental protection materials, and specifically relates to a modified kaolin algaecide, a preparation method and application thereof. Background Art

[0002] The frequent occurrence of blue algae blooms has become a global problem that needs to be solved urgently in the field of water environment. Blue algae blooms were once considered "cancer" in the water. It is very difficult to control them, and the sustained effect is limited. After using algaecides without algaecide ability, the flocculated and settled blue algae will revive again and become a disaster. In addition, the dosage of traditional flocculant algaecides is often too large, and there are certain ecological risks, such as causing large-scale deaths of fish in the water.

[0003] The commonly used algaecides are difficult to play a good algae control effect in large rivers and lakes, and are not suitable for water bodies with rich aquatic biodiversity and outstanding ecological service functions. Therefore, it is extremely urgent to develop new algaecides that are both cost-effective, have good sustained algae killing effects, and are highly environmentally friendly.

[0004] At present, among the many methods for controlling cyanobacterial blooms, the modified clay mineral flocculation algae removal method is recognized as one of the most promising methods, and is often used in the on-site control of large-scale harmful algae, becoming an important emergency measure for algal blooms. Kaolin, as one of the typical natural clay minerals, has broad application prospects in water treatment due to its unique structure and properties. However, since natural kaolin generally contains a large amount of impurities, its effect in practical applications is not ideal. Therefore, if kaolin can be modified to enhance its adsorption performance, it can be better used in the process of inhibiting algae and purifying water, which is of great significance to the prevention and control of cyanobacterial blooms.

[0005] The following literature has reported on the technical solution of using modified kaolin as raw material to remove common algae in water:

[0006] A document titled "Experimental Study on Removal of Common Algae in Water by Chitosan-Modified Kaolin" disclosed that chitosan-modified kaolin is used to inhibit algae, and the algae cell removal rate of the modified kaolin reaches about 70%, which is still relatively limited; and the kaolin modified by this method still has the problems of insufficient stability, long treatment response time, and can flocculate and settle algae, but has no algae killing ability. The settled algae are at risk of being suspended again and becoming a disaster.

[0007] There are also documents that disclose the use of chitosan polyammonium salt to modify river sand to remove algae, but the composition structure of river sand varies greatly and is complex, the exact mechanism is difficult to explain, the experimental reproducibility is poor, the quality control of large-scale products is difficult to guarantee, and standardized production is difficult.

[0008] Therefore, it is necessary to further improve the above-mentioned method and invent a modified kaolin algaecide agent with better algaecogenic effect and high environmental friendliness. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides an algaecide obtained by modifying kaolin with chitosan polyammonium salt and allelopathic agent, and also provides a preparation method of the algaecide and the application of the algaecide in the treatment of algal bloom water bodies. Since kaolin is modified by quaternary ammonium salt and allelopathic agent, the algae removal performance of the modified kaolin is enhanced, and it has the characteristics of rapid flocculation, efficient coagulation and sedimentation, sustainable algae killing and algae inhibition, etc.

[0010] The composite algaecide provided by the present invention has the advantages that its raw material kaolin is abundant and inexpensive, has negative charges, has a large surface cation exchange capacity, and has abundant active groups such as hydroxyl groups on the surface, making it easy to modify. Its layered structure and hydration make it easy for water molecules to adhere to the mineral surface in a chemical adsorption manner, which can promote the catalytic reaction, all of which provide more possibilities for the modification of kaolin.

[0011] The allelopathic agents used have eco-friendly properties in controlling algae, so allelopathic algae control is considered to be a very promising method for controlling algal blooms, especially in the prevention and control of cyanobacteria in high-functional water bodies such as drinking water sources and nature reserves.

[0012] The algaecide provided by the present invention has the following dosage ratios of various raw materials:

[0013] The weight volume ratio of chitosan quaternary ammonium salt to water is 1 g: (45-100) mL, and the mass volume concentration of the allelopathic agent is 5-80 mg / L;

[0014] The weight ratio of kaolin to chitosan quaternary ammonium salt is 5-40:1.

[0015] The above algaecide is obtained by the following preparation method:

[0016] The steps include:

[0017] S1: dissolving chitosan quaternary ammonium salt in water, heating to 60-100°C, stirring continuously to dissolve it, then adding allelopathic agent, and continuing stirring until fully dissolved to obtain a mixed solution of chitosan quaternary ammonium salt-allelopathic agent;

[0018] S2 weighs kaolin and adds it to the mixed solution of chitosan quaternary ammonium salt-allelopathic agent prepared in S1, and continues stirring at 60-90°C. After forming a slurry, it is subjected to ultrasonic treatment with an ultrasonic power of 300-1500W and a duration of 8-30min. The slurry obtained by ultrasonic treatment is dried, cooled and ground into powder to obtain a modified kaolin algaecide inhibitor.

[0019] The present application specifically combines the organic flocculant chitosan quaternary ammonium salt (HACC) with the allelopathic agent to modify it, giving it the effect of rapid flocculation and continuous algaecide and algae inhibition, and experiments have proved that the algae inhibitor has the effect of continuous algae control and algae inhibition, and is particularly suitable for emergency treatment of cyanobacteria blooms, and can effectively prevent secondary outbreaks of algae blooms.

[0020] In the present application, HACC and allelopathic substances are used in combination, and compared with single HACC modified kaolin, the algae control and algae inhibition effect is more excellent.

[0021] The beneficial effects of the present invention are:

[0022] (1) The quaternary ammonium salt of chitosan and allelopathic agents, especially linoleic acid, were used together to ultrasonically modify kaolin at a specific temperature. The granular agglomeration of the modified kaolin algaecide obtained was more significant, and the number of surface pores of the algaecide increased, and the specific surface area and the number of adsorption sites increased (such as the attached Figure 2 The above conclusions can be drawn from the morphological analysis of the modified kaolin shown in (a)-(c), which is conducive to the algae inhibitor combining with more algae cells to form larger flocs, thus achieving a good algae inhibition effect;

[0023] For example, when kaolin:HACC=12:1, the dosage of modified kaolin algaecide is 70mg / L, and the concentration of linoleic acid is 14mg / L, the actual average values ​​of turbidity removal rate, algae precipitation rate and algae killing rate are 94.08%, 93.60% and 93.76% respectively;

[0024] (2) In the experiment of inhibiting cyanobacteria bloom, it was found through long-term monitoring and observation that the algaecide prepared by the method of the present invention showed a good inhibitory effect on the activity of algae flocs, that is, the algaecide and algaecide method of the present invention have the characteristics of continuous algae inhibition. This conclusion provides the possibility of inhibiting the secondary outbreak of cyanobacteria. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The algae removal effect of the kaolin algae inhibitor modified by HACC combination with different allelopathic substances in Experimental Example 1 of the present invention;

[0026] Figure 2 The surface morphology electron microscope images of different modified kaolin algaecide inhibitors in Experimental Example 2 of the present invention;

[0027] Figure 3 The electron microscope images of algae flocs obtained by using different modified kaolin algae inhibitors in Experimental Example 2 of the present invention;

[0028] Figure 4 The photosynthetic activity F of the original algae solution and each algae floc in Experimental Example 2 of the present invention v / F mchanges over time;

[0029] Figure 5 The algae cell density and Chl _ a concentration, turbidity and photosynthetic activity of algae v / F m Changes in circumstances;

[0030] Figure 6 The graph shows the changes of TN, TP and TN / TP in each water bloom group before and after algae removal in Experimental Example 3 of the present invention over time. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in conjunction with specific implementation methods.

[0032] Example 1

[0033] A modified kaolin algaecide is prepared by the following method:

[0034] S1 Accurately weigh 1g chitosan quaternary ammonium salt into a beaker, add 100mL distilled water, and place the beaker in a 65℃ water bath, stir with a glass rod to dissolve it, then add 20mg allelopathic agent linoleic acid, continue to stir with a glass rod to fully dissolve it, and obtain a chitosan quaternary ammonium salt-linoleic acid mixed solution;

[0035] S2 weighs 15g of kaolin and adds it to the chitosan quaternary ammonium salt-linoleic acid mixed solution prepared in S1, and heats and stirs it in a water hot pot at 65°C. After forming a slurry, it is subjected to ultrasonic treatment using an ultrasonic cell disruptor with a power of 300W. The intermittent ultrasonic treatment lasts for a total of 10 minutes (with a 30s break for every 1 minute of ultrasonic treatment) to ensure that the mixture is fully mixed. Finally, the obtained slurry is heated and dried in an oven at 85°C. After cooling, it is taken out and ground into powder to prepare a HACC-linoleic acid modified kaolin algaecide agent.

[0036] Example 2

[0037] The difference from Example 1 is that the allelopathic agent used in S1 is catechol, and the dosage is 10 mg to prepare a HACC-catechol-modified kaolin algaecide.

[0038] Example 3

[0039] The difference from Example 1 is that the allelopathic agent used in S1 is pyrogallic acid, and the dosage is 5 mg, so as to prepare a HACC-pyrogallic acid-modified kaolin algaecide.

[0040] Example 4

[0041] The method of Example 1 was adopted to set the modification temperature in S2 to 40°C, 50°C, 60°C, 70°C and 80°C, respectively, to examine the effect of temperature on the modification. The results showed that temperature also had a certain influence on the modification. The algae inhibition effect was better when the modification treatment was carried out at a temperature of 60°C to 70°C.

[0042] Example 5

[0043] The ultrasonic duration in S2 was set to 2 min, 3 min, 4 min and 6 min respectively. The results showed that the modification treatment effect was better when the ultrasonic duration was 4 min.

[0044] Example 6

[0045] The modified kaolin algaecide was prepared by mixing HACC, linoleic acid and kaolin without ultrasonic treatment. Kaolin and HACC were not ultrasonically dispersed, and their solubility was poor. Simply mixing could not achieve the purpose of full fusion, and the treatment effect was poor. Therefore, ultrasonic treatment can make the raw materials mixed more evenly and the algaecide effect is better.

[0046] Comparative Example 1

[0047] Different from Example 1, no allelopathic agent was added in S1, and only HACC was used to modify kaolin.

[0048] Comparative Example 2

[0049] Different from Example 1, HACC was not added in S1, and only allelopathic agent was used to modify kaolin.

[0050] Test Example 1

[0051] The modified kaolin composite algaecide obtained in Example 1-3 and Comparative Example 1-2 was added to the water containing Microcystis aeruginosa grown to the logarithmic phase at a feed ratio of 60 mg / L for algae reduction treatment.

[0052] The turbidity, algae density and chlorophyll-a (Chl _ a) The removal rates of the three were comprehensively investigated. The algae reduction effects of the modified kaolin algae inhibitors obtained by different modification treatments were investigated. The turbidity of the water body was measured by scattering method (turbidimeter, Leici, Shanghai); the algae density was measured by blood cell counting method (25×16) (inverted microscope, Olympus, Japan); the chlorophyll a content in the algae solution can be directly measured by phytoplankton classification fluorescence instrument (PHYTO-PAM-II). Due to the high chlorophyll concentration, the sample was diluted to within the upper limit of PHYTO-PAM-II (300μg / L) before the measurement. The sample was adjusted to zero with distilled water, and after dark adaptation for 30 minutes, the chlorophyll content of the algae was measured under the measurement light of 32 light frequency.

[0053] The algae-reducing treated samples were placed in a light incubator for further culture, and the supernatant was taken to determine Chl _ a concentration, which represents the biomass of algae and plots the Chl _ a growth curve of concentration change over time. The specific experimental results are shown in Table 1-2 and the attached Figure 1 shown.

[0054] Table 1 Algae reduction effect of modified kaolin algae inhibitors with different modification treatments

[0055]

[0056] Table 2 Growth changes of algae over time after algae reduction by composite algaecide Chl _ a(μg / L)

[0057] Time (d) 0 1 2 3 5 7 10 13 16 No algaecide added 726.05 880.82 972.46 1496.34 1892.45 1782.62 2631.27 2874.81 3275.46 Comparative Example 1 45.13 114.37 184.37 193.90 233.60 645.10 1139.27 1478.67 1749.33 Comparative Example 2 28.32 89.71 104.98 112.06 176.86 243.13 462.74 789.69 942.64 Example 1 23.00 40.47 47.60 57.73 64.50 103.57 118.93 194.67 245.90 Example 2 38.20 68.07 120.50 120.70 167.13 337.03 485.93 738.08 1023.67 Example 3 233.63 378.07 612.37 811.23 1652.08 2213.88 3115.75 3333.67 3792.00

[0058] Table 1 and Appendix Figure 1 a shows that the HACC modified kaolin algae inhibitor without allelopathic agent in comparative example 1 is used as a control group, and the algae reduction effect of the modified kaolin algae inhibitor after HACC combined with linoleic acid, catechol, and pyrogallic acid in Examples 1-3 is compared to investigate the effect of allelopathic agent on the algae reduction effect of HACC modified kaolin. The details are as follows:

[0059] The algae-reducing effects are ranked from largest to smallest as follows: "kaolin + HACC + linoleic acid" > "kaolin + HACC" > "kaolin + HACC + catechol" > "kaolin + HACC + pyrogallic acid", that is, the effects are ranked from largest to smallest as follows: Example 1, Comparative Example 1, Example 2, and Example 3.

[0060] Turbidity, algae density and Chl of algae solution of HACC modified kaolin algae inhibitor _ aThe removal rates of the three were all above 90%; the removal rates of the kaolin algaecide modified by HACC combined with pyrogallic acid significantly reduced (P < 0.05), which was about 30% lower than that of the control group; it can be seen that the addition of the allelopathic agent pyrogallic acid will have an adverse effect on the algaecide effect of HACC modified kaolin.

[0061] The turbidity and removal rate of the algae inhibitor modified by HACC and catechol (Example 2) were not significantly different from those of the control group (P>0.05). The algae density was similar to that of Chl _ The removal rates of a decreased slightly;

[0062] The removal rates of the three algae inhibitors modified by HACC combined with linoleic acid (Example 1) were not reduced but increased, and the removal rates of the three algae inhibitors were all around 95%. Compared with the control group, the removal rates of the three algae inhibitors were increased by 6.73%, 5.37% and 5.02%, respectively.

[0063] By comparing the algae-reducing effects of modified kaolin with and without allelopathic agents combined with HACC, it can be found that pyrogallic acid has an adverse effect on the algae-reducing effect of HACC-modified kaolin (Example 3), catechol has little effect on the algae-reducing effect of HACC-modified kaolin (Example 2); linoleic acid promotes the algae-reducing effect of HACC-modified kaolin (Example 2).

[0064] It can be seen that although they are allelopathic substances, the algae inhibition effects of HACC-modified kaolin and different allelopathic substances are different. On the contrary, some allelopathic substances combined with HACC-modified kaolin will have adverse effects. Not all algae-inhibiting substances can be combined or superimposed to enhance the effect.

[0065] Attached Figure 1 b shows the changes in algae growth over time in each group after HACC without allelopathic agent and modified kaolin obtained by combining pyrogallic acid, catechol and linoleic acid. It can be clearly seen from the figure that the algae inhibition effect is from large to small: "kaolin + HACC + linoleic acid" > "kaolin + HACC + catechol" > "kaolin + HACC" > "kaolin + HACC + pyrogallic acid".

[0066] After algae removal, the Chl content of residual algae in the modified kaolin obtained by the control group and HACC combined with pyrogallic acid, catechol and linoleic acid was _ a concentrations were 118.9μg / L, 445.3μg / L, 203.9μg / L and 44.9μg / L, respectively. As time went by, the Chl _ The concentration of a in the control group grew slowly in the first three days of the experiment, and accelerated from the fifth day and entered the logarithmic growth period; the algae in the group of modified kaolin algaecide combined with HACC pyrogallic acid began to grow rapidly after one day of the experiment, and its growth rate was much higher than that of other groups. After 15 days of the experiment, its Chl _ The concentration of a increased to 3900μg / L, which was twice that of the control group; the algae in the HACC combined with catechol group began to grow significantly from the 7th day of the experiment, and the growth rate of the algae slowed down significantly compared with the control group; while the residual algae in the HACC combined with linoleic acid group showed almost no obvious growth trend from the beginning of algae reduction to the end of the experiment.

[0067] By comparing the algae inhibition effects of modified kaolin with or without HACC combined with allelopathic agents, it was found that the modified kaolin algae inhibitor after HACC combined with catechol and linoleic acid had a good inhibitory effect on algal flocs and residual algae, among which linoleic acid had the strongest algae inhibition ability. Therefore, it is believed that the use of linoleic acid in modified clay to control algal blooms and prevent their secondary outbreaks has great potential.

[0068] In summary, the modified kaolin after HACC combined with linoleic acid not only did not weaken its algae flocculation ability, but also had a strong inhibitory effect on the regrowth of algae flocs and residual algae to maintain a long-term algae control state. Therefore, in the present invention, linoleic acid was finally selected as the allelopathic agent, which was combined with HACC to modify kaolin, and the modified kaolin algae inhibitor was applied to the removal test of blue algae in the wild.

[0069] Next, the response surface analysis method of Box-Behnken design (BBD) was used, with the ratio of kaolin to HACC, the dosage of modified kaolin algaecide, and the concentration of linoleic acid as influencing factors, and the turbidity removal rate (turbidity removal rate), algae settling rate, and algaecide rate as response values. Each response value corresponds to 17 BBD analysis experiments. The response surface experimental design factors and levels are shown in Table 3 below, and the specific experimental design scheme and results are shown in Table 4 below.

[0070] Table 3 Response surface experimental design factors and levels

[0071]

[0072] Table 4 Response surface experimental design scheme and its results

[0073]

[0074]

[0075] The optimal algae inhibition conditions obtained from the above response surface model are: the weight ratio of kaolin: HACC is 11.79:1, the dosage of modified kaolin algae inhibitor is 68.69 mg / L, and the concentration of linoleic acid is 13.78 mg / L. According to actual needs, the optimal process conditions for algae removal by HACC combined with linoleic acid modified kaolin are further modified to: kaolin: HACC = 12:1, the concentration of linoleic acid is 14 mg / L, and the dosage of modified kaolin algae inhibitor is 70 mg / L. Three groups of parallel experiments were set up for verification. The experimental results are shown in Table 5 below.

[0076] Table 5 Predicted and measured values ​​of algae removal by HACC combined with linoleic acid modified kaolin

[0077]

[0078] It can be seen from Table 5 that when kaolin:HACC=12:1, the dosage of modified kaolin algaecide is 70 mg / L, and the linoleic acid concentration is 14 mg / L, the theoretical predicted values ​​of the turbidity removal rate, algae precipitation rate and algaecide rate obtained by the regression equations are 93.80%, 92.92% and 92.43% respectively; under this condition, the actual measured average values ​​of the turbidity removal rate, algae precipitation rate and algaecide rate are 94.08%, 93.60% and 93.76% respectively.

[0079] Test Example 2

[0080] A modified kaolin algaecide was prepared by the method in Example 1. Similarly, the weight ratio of kaolin to HACC was 15:1. The difference from Example 1 was that the concentration of linoleic acid was 12.5 mg / L, and the other conditions and parameters were exactly the same.

[0081] 2.1 Morphological analysis of modified kaolin algaecide

[0082] At the same time, the morphology of the original kaolin and the kaolin modified by HACC in Comparative Example 1 were used as controls. The surface morphology of different composite algaecides was shown in the attached electron microscopy images. Figure 2 shown.

[0083] Attached Figure 2 (a) from left to right are SEM images of kaolin ore at 1.00k×, 5.00k× and 10.00k×; Figure 2 (b) from left to right are SEM images of HACC modified kaolin algaecide under 1.00k×, 5.00k× and 10.00k×; Figure 2 From left to right in (c) are SEM images of HACC+linoleic acid modified kaolin algaecide at 1.00k×, 5.00k× and 10.00k× respectively.

[0084] Depend on Figure 2 (a)-(c) show that the surface of the original kaolin is relatively smooth and loosely dispersed. Compared with the original kaolin, the surface morphology of the modified kaolin has changed significantly, with many dense and compact lumps appearing. Its surface has become rougher and has quite a lot of pores, which provides more adsorption contact sites for algae cells. In addition, through Figure 2 (b) and (c) compare the surface morphology of kaolin modified with or without HACC combined with linoleic acid. It is found that the agglomerates in the modified kaolin combined with linoleic acid are larger than those without linoleic acid, which makes the algal flocs easier to precipitate.

[0085] In summary, HACC+linoleic acid modified kaolin can make kaolin particles aggregate larger, increase the number of agglomerates and their surface pores, increase the specific surface area and the number of adsorption sites, and can combine with more algal cells to form larger flocs, thereby improving the algae flocculation ability.

[0086] 2.2 Analysis of algal floc surface morphology

[0087] Take HACC alone, HACC modified kaolin (kaolin: HACC = 15: 1) and HACC combined with linoleic acid modified kaolin (kaolin: HACC ratio = 15: 1, linoleic acid is 12.5 mg / L). In this embodiment, the ratio of kaolin: HACC = 15: 1 or 12: 1. The principle of characterization and analysis is the same, and the trend is the same. Therefore, the scheme in Example 1 is adopted, and the most preferred ratio is not adopted. The algae flocs obtained under the above conditions are subjected to SEM analysis. The SEM results and the experimental conditions and removal rates of the three algae flocs are shown in the attached Figure 3 and Table 6.

[0088] Table 6 Experimental conditions and removal rate of algae flocs

[0089]

[0090] Attached Figure 3 (a) from left to right are SEM images of HACC flocculated algae flocs at 1.00k× and 5.00k; Figure 3 (b) from left to right are SEM images of HACC modified kaolin flocculated algae flocs at 1.00k× and 5.00k×; Figure 3 From left to right in (c) are SEM images of HACC+linoleic acid modified kaolin flocculated algae flocs at 1.00k× and 5.00k× respectively.

[0091] By the attached Figure 3 (a) It can be seen that the algae cells are bonded and condensed together by the HACC molecular chains, and the flocs are relatively loose without covering. It can be seen that HACC can use its polymer chains as a bridge to connect the algae to form an algae-polymer-algae aggregate, indicating that chitosan flocculation and algae removal alone has a bonding and bridging effect.

[0092] The flocculation and algae removal mechanisms of kaolin modified by chitosan quaternary ammonium salt include bonding bridging and net capture and sweeping, which play a major role in the flocculation and algae removal process of modified kaolin.

[0093] 2.3 Photosynthetic activity index F v / F m Determination of

[0094] In order to explore the effect of modified kaolin flocculation on the photosynthesis of algae cells in algae flocs, PHTYO-PAM-Ⅱ was used to determine the photosynthetic activity index F of algae flocs. v / F m .

[0095] F v / F m It is an important indicator that reflects the changes in the photosynthesis of plants or algae when they are under stress, and reflects the potential maximum light energy conversion efficiency of plants or algae. v / F m It is also the maximum potential photosynthetic efficiency of phytoplankton and the most core indicator reflecting the physiology of algae cells.

[0096] Table 7 and attached Figure 4 The photosynthetic activity of the original algae solution and each algae floc is shown. v / F m Changes over time, where "CK" is the control group of the original algae solution without flocculant addition (logarithmic period, algae density is about 4.88×10 6 / mL), "algae floc-1", "algae floc-2" and "algae floc-3" are the algae flocs produced by adding HACC, HACC modified kaolin algae inhibitor, and HACC + linoleic acid modified kaolin algae inhibitor to the original algae, respectively.

[0097] Table 7 Photosynthetic activity of original algae solution and algae flocs v / F m Changes over time

[0098] Time (d) 0 4 8 12 16 20 CK 0.34 0.45 0.43 0.48 0.58 0.66 Algae floc-1 0.31 0.62 0.67 0.70 0.72 0.75 Algae floc-2 0.29 0.44 0.39 0.50 0.53 0.58 Algae floc-3 0.21 0.32 0.16 0.20 0.29 0.46

[0099] The results showed that in the 20-day monitoring experiment of photosynthetic activity of Prototheca and its flocs, the photosynthetic activity F v / F m : "Algal floc-1" > "CK" > "Algal floc-2" > "Algal floc-3".

[0100] Among them, the F of the "CK" group v / F m Over time, it showed a trend of "slowly rising with fluctuations"; the F of the "algae floc-1" group v / F m There was a rapid upward trend in the first four days of the experimental period, and the growth rate slowed down from the fourth day. v / F m The value increased from 0.30 to 0.65, twice as much as before the experiment; the F v / F m , which is basically consistent with the growth trend of the “CK” group, but F v / F m During the test period, the results of F in the “CK” group were slightly lower than those in the “Algae Floc-3” group. v / F m During the entire test period, it maintained an overall downward trend, dropping from 0.3 before the test to around 0.1.

[0101] That is, the activity of algal flocs obtained by using HACC alone was even higher than that of algal cells in the original algal solution, indicating that HACC can promote the photosynthesis of algae by increasing the photosynthetic activity of algal flocs, which will be detrimental to the removal of algae.

[0102] In addition, the algae floc activity obtained by HACC modified kaolin algae inhibitor was slightly lower than the algae cell activity in the original algae solution, indicating that the use of HACC modified kaolin to reduce algae had a certain inhibitory effect on the photosynthesis of algae; and compared with the HACC modified kaolin algae inhibitor, the algae floc activity of the algae inhibitor obtained by using HACC + linoleic acid modified kaolin showed a downward trend, indicating that linoleic acid, an allelopathic agent, can effectively reduce the photosynthetic activity of algae to inhibit the photosynthesis of algae. Therefore, it can be considered that the algae inhibitor obtained by combining HACC with linoleic acid modified kaolin provides a possibility for inhibiting the secondary outbreak of algae.

[0103] Test Example 3

[0104] Source of wild algae: On October 30, 2023, a blue algae bloom broke out in a water area isolated from the middle branch of the Ganjiang River near Yaozui, Dongzhen, Nanchang County, covering an area of ​​about 480m 2 , sampled at 10 cm below the water surface, put the algae sample into a 15L polyethylene plastic bucket and brought it back to the laboratory, where it was stored in an open refrigerator at 5°C. Microscopic observation showed that the algae in the cyanobacteria sample were mainly Microcystis. After stirring evenly, the algae density of Microcystis in the algae sample was about 2.31×10 6 cells / mL.

[0105] The cyanobacteria stock solution retrieved from the algae-containing pond was placed in a 50L glass tank as experimental water, and high- and low-density bloom control groups were prepared (high-density bloom: about 2.0×10 9 cells / L; low-density bloom: about 2.0×10 7 cells / L) and high and low density bloom treatment groups were used for pairwise comparison experiments ( Figure 5 ).

[0106] The control group is: the HACC modified kaolin group in Experimental Example 1, that is, Comparative Example 1 group.

[0107] The algaecide suspension was prepared according to the optimal algae removal process conditions (kaolin: HACC = 12:1, the concentration of linoleic acid was 14 mg / L, and the dosage of modified kaolin algaecide was 70 mg / L) and poured into the high and low density water bloom treatment groups respectively. The algae removal test was carried out under normal conditions. After the test, water samples were taken at 5 cm from the liquid surface after settling for 1 hour. The turbidity, algae cell density, Chl _ a concentration and other indicators.

[0108] In order to verify the actual application effect of HACC+linoleic acid modified kaolin algae inhibitor on the removal of cyanobacteria in the wild, the turbidity, algae density, Chl _ The algae flocculation and algae inhibition effects of the algaecide were investigated by using indicators such as a concentration, and the changes in the above indicators in the water were continuously monitored for about half a month after the algae reduction to observe the subsequent effects of the algae inhibitor on the algae.

[0109] Figure 5 Comparison of algae removal effect before and after drug administration (comparison of algae density, Chl _ a concentration, turbidity and algae photosynthetic activity), it can be seen that the HACC combination of linoleic acid-modified kaolin has a significant effect on the removal of wild cyanobacteria.

[0110] Before the experiment, the algae density and Chl _ a concentration and turbidity were 1.66×10 6 cells / mL, 780.1μg / L and 204NTU, respectively, after the experiment, they dropped to 0.064×10 6 cells / mL, 31.74μg / L and 5.84NTU, with removal efficiencies of 96.14%, 95.93% and 97.14%, respectively.

[0111] Figure 6 It is the algae cell density of the algae solution in the water within half a month before and after the test, Chl _ a concentration, turbidity and photosynthetic activity of algae v / F m Changes in situation.

[0112] The results showed that the algae density in water and Chl _ a concentration changes in the same trend, about one week after the experiment, the high-density bloom control group algae density and Chl _The concentration of a decreased with the passage of time, while that of the low-density water bloom control group increased and finally tended to be relatively stable. The algae density in the treatment group remained stable at a low level during the experimental period, and there was almost no upward trend. The turbidity of the water in the control group decreased rapidly due to self-purification, and then tended to be stable. The turbidity of the treatment group was almost 0 after the experiment, and remained stable during the 16-day continuous monitoring period. The photosynthetic activity of the algae in the control group fluctuated between 0.2 and 0.4, among which the activity of the algae in the low-density water bloom control group was slightly higher than that in the high-density water bloom control group. After 2 days of the experiment, the photosynthetic activity of the algae in the treatment group rapidly dropped to near 0, and returned to normal levels after about a week.

[0113] The results showed that the composite algaecide obtained by combining HACC with linoleic acid-modified kaolin had an effect on algae density, Chl _ a and turbidity removal rates were over 95%, and the algae density, Chl _ There was no significant change in the concentration of a and the turbidity of water during the test period, indicating that the addition of HACC combined with linoleic acid modified kaolin algae inhibitor can maintain a good algae flocculation effect for a long time and effectively prevent the algae residue in the water from floating up; and after using HACC combined with linoleic acid modified kaolin algae inhibitor to remove algae, the activity of residual algae in the water dropped significantly (even close to 0 on the second day of the test), and this state lower than the normal algae activity can last for about a week, indicating that linoleic acid has a deactivating effect on wild cyanobacteria.

[0114] Effects of HACC combined with linoleic acid modified kaolin algaecide on nutrient concentration in water bodies.

[0115] In order to explore the effect of the application of HACC combined with linoleic acid modified kaolin algae inhibitor on the re-release of nitrogen and phosphorus nutrients in water bodies, the total nitrogen (TN) and total phosphorus (TP) of algae-containing water before and after algae removal were monitored for about half a month. The test results are shown in the attached Figure 6 .

[0116] As attached Figure 6 As shown, the changes of TN, TP and TN / TP in each water bloom group before and after algae removal over time.

[0117] The results showed that the concentration of TN in the treatment group did not change significantly before and after algae removal, and there was no significant difference compared with the control group (P>0.05). During the experimental period, the TN of the control group and the treatment group was stable between 24 and 26 mg / L; while the TP concentration was significantly reduced compared with the control group (P<0.01), among which the TP concentration change in the high-density water bloom treatment group was more obvious. The concentration of TP in the water before algae removal was 1.19 mg / L. After algae removal using HACC combined with linoleic acid-modified kaolin, its concentration value became 0.48 mg / L, and the removal rate of TP was 59.66%. After algae removal, the TP concentrations in the high- and low-density water bloom treatment groups were roughly equal, and showed a slight downward trend over time during the experimental period. Before algae removal, the TN / TP ratio in the water of the high- and low-density water bloom treatment groups was about 22:1, and the TN / TP values ​​were close after 1 day of the algae removal experiment, both rising to above 50:1. During the experimental period, the TN / TP value of the control group was stable at around 25:1, while that of the treatment groups showed a continuous upward trend over time, among which the increasing trend of TN / TP in the high-density water bloom treatment group was more significant, and the TN / TP value reached 78:1 on the last day of the experiment.

[0118] The results show that the use of HACC combined with linoleic acid modified kaolin flocculation algae removal has little effect on the concentration of TN in the water body, but has a significant removal effect on TP; after the algae cells are flocculated and settled to the bottom of the water, the TP in the water has not changed significantly during the 16-day continuous monitoring period, indicating that the algaecide can inhibit the release of total phosphorus in the water for a long time. In addition, some scholars believe that the nitrogen-phosphorus ratio in water is a potential factor inducing the outbreak of cyanobacteria, and TN / TP does not exceed 29:1 when cyanobacteria bloom occurs. In the algae removal experiment of the present invention, the ratio of total nitrogen to total phosphorus in the water after algae removal greatly exceeds 29:1, and it can maintain a stable upward trend during the 16-day experimental period. Therefore, it can be judged that the use of HACC combined with linoleic acid modified kaolin algae removal can prevent the secondary outbreak of cyanobacteria in the water for a long time.

Claims

1. A modified kaolin algaecide, characterized in that: The algae inhibitor is obtained by modifying kaolin with chitosan quaternary ammonium salt and allelopathic agent; The modification steps are as follows: Dissolve chitosan quaternary ammonium salt in water at 80-100°C, add allelopathic agent after fully dissolved, stir to blend; then add kaolin and stir evenly, subject the mixed material to ultrasonic treatment with an ultrasonic power of 300-1500W and a duration of 8-30min, so as to obtain a modified kaolin algaecide inhibitor.

2. The modified kaolin algaecide according to claim 1, characterized in that: The allelopathic agent is linoleic acid, a natural secondary metabolite of plants.

3. The modified kaolin algaecide according to claim 1, characterized in that: The weight volume ratio of chitosan quaternary ammonium salt to water is 1g: (45-100) mL, and the mass volume concentration of the allelopathic agent is 5-80 mg / L; The weight ratio of kaolin to chitosan quaternary ammonium salt is 5-40:

1.

4. The method for preparing a modified kaolin algaecide inhibitor according to claim 1, characterized in that: The steps include: S1: dissolving chitosan quaternary ammonium salt in water, heating to 60-100°C, stirring continuously to dissolve it, then adding allelopathic agent, and continuing stirring until fully dissolved to obtain a mixed solution of chitosan quaternary ammonium salt-allelopathic agent; S2 weighs kaolin and adds it to the mixed solution of chitosan quaternary ammonium salt-allelopathic agent prepared in S1, and continues stirring at 60-90°C. After forming a slurry, it is subjected to ultrasonic treatment with an ultrasonic power of 300-1500 W and a duration of 8-30 min. The slurry obtained by ultrasonic treatment is dried, cooled, and ground into powder to obtain a modified kaolin algaecide inhibitor.

5. Use of the modified kaolin algae inhibitor according to claim 1 in treating blue algae blooms, characterized in that: The amount of modified kaolin algaecide inhibitor added is (40~80) mg per liter of algal bloom water.

6. Use of the modified kaolin algae inhibitor according to claim 1 in treating water bodies polluted by blue algae blooms, characterized in that: Take the modified kaolin algae inhibitor and add it to the water body to be treated at a dosage of 40-80 mg per liter of blue algae bloom at room temperature. When adding, stir it by spraying the suspension and pumping.

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