Floating type copper-loaded sodium alginate hydrogel ball as well as preparation method and application thereof

Abstract

The invention relates to a floating type copper-loaded sodium alginate hydrogel ball as well as a preparation method and application thereof, and belongs to the technical field of water ecological restoration. The technical problem to be solved by the invention is to provide the preparation method of the floating type copper-loaded sodium alginate hydrogel ball. The method comprises the following steps: preparing a solution A and a solution B, wherein the solution A is prepared from sodium alginate, citrate, an acidic pH regulator, hydrogen peroxide and water; the solution B consists of copper sulfate pentahydrate, citrate, a pH regulator and water; dropwise adding the solution A into the solution B to obtain hydrogel balls; and filtering and washing. The hydrogel ball can float on the water surface and release copper ions in a low dosage for a long time, blue-green algae on the water surface are continuously killed, the influence on the water body is small, and the risk of water body pollution caused by excessive copper ion release can be greatly reduced; the algicide feeding device can effectively reduce the feeding frequency of the algicide, also reduces the labor cost caused by long-period feeding of the algicide, can float on the water surface, is easy to recycle, and does not cause secondary pollution to the water body.

Description

Technical Field

[0001] The invention relates to a floating copper-loaded sodium alginate hydrogel ball and a preparation method and application thereof, belonging to the technical field of water ecological restoration. Background Art

[0002] In recent years, the outbreak of cyanobacteria caused by eutrophication has brought many problems. When cyanobacteria blooms occur, they will lead to the deterioration of the water environment, cause the death of other aquatic organisms and further deteriorate the environment. Cyanobacteria have pseudocavities, which can provide them with buoyancy and thus regulate their distribution in the water body. When the temperature gradually rises, cyanobacteria will gradually rise to the water surface and form a bloom on the water surface.

[0003] Currently, cyanobacteria bloom control technologies can be divided into three categories: physical, chemical, and biological methods. Among them, chemical algae control technology mainly achieves bloom control effects through chemical algaecides and chemical flocculants. It has the advantages of fast speed and good effect, so it is often used as an emergency treatment method during cyanobacteria bloom outbreaks.

[0004] As a type of chemical algaecide, copper-based algaecides have been used as algaecides for more than 100 years in history due to their economic, effective, relatively safe and easy operation. The principle of copper-based algaecides is mainly that copper ions interfere with the normal metabolism and biochemical reactions of algae through their strong affinity for sulfur-containing groups on the surface of algal cell walls, thereby inhibiting algae growth. At the commonly used dose (0.025-1 ppm), copper-based algaecides are considered to have no significant effect on human health. At present, my country's surface water environmental quality standards require that the copper content in Class II-V water should not exceed 1 ppm. Therefore, copper-based algaecides have become a research hotspot for researchers in this field.

[0005] Patent application number CN 118833897 A discloses a method for improving the algae removal effect of copper-loaded biochar, which uses inorganic salt ions to increase the particle size of copper-loaded biochar particles, improve the contact efficiency between copper-loaded biochar and algae, and increase the salt stress and cell membrane damage of algae cells, thereby improving the algae removal efficiency. Although the algaecide can improve the algae removal efficiency, it is easy to overdose the algaecide when treating blue algae blooms, resulting in secondary pollution to the water body. Therefore, in the actual treatment process, a small amount of multiple times is usually used for placement, which will consume a lot of manpower and material resources. The algaecide still has the defects of short action time, long placement cycle, and easy to exceed the standard, thereby causing heavy metal pollution in water bodies and sediments. Summary of the invention

[0006] In view of the above defects, the first technical problem solved by the present invention is to provide a method for preparing a novel floating copper-loaded sodium alginate hydrogel sphere capable of long-term sustained release.

[0007] The preparation method of the floating copper-loaded sodium alginate hydrogel sphere of the present invention comprises the following steps: 1) preparing solution A and solution B, wherein solution A consists of sodium alginate, citrate, an acidic pH regulator, hydrogen peroxide and water; solution B consists of copper sulfate pentahydrate, citrate, an acidic pH regulator and water; 2) Add solution A dropwise into solution B, stir during the addition, and let stand after the addition is complete to obtain hydrogel spheres; 3) The hydrogel balls are filtered out and the copper sulfate on the surface is removed by washing to obtain floating copper-loaded sodium alginate hydrogel balls.

[0008] In one embodiment of the present invention, in step 1), the citrate is trisodium citrate or copper citrate; and the acidic pH regulator is citric acid.

[0009] In one embodiment of the present invention, in step 1), the citrate is trisodium citrate; and the acidic pH regulator is citric acid.

[0010] In one embodiment of the present invention, in solution A of step 1), the mass concentration of hydrogen peroxide is 1% to 4%; the concentration of sodium alginate is 0.5 to 2.5 g / 100 mL; the concentration of trisodium citrate is 0.74 to 5.88 g / 100 mL, and the concentration of citric acid is 0.53 to 4.2 g / 100 mL; in solution B, the concentration of copper sulfate pentahydrate is 5 to 37 g / 100 mL, the concentration of trisodium citrate is 0.74 to 5.88 g / 100 mL, and the concentration of citric acid is 0.53 to 4.2 g / 100 mL.

[0011] In a preferred embodiment of the present invention, in solution A, the mass concentration of hydrogen peroxide is 3% to 4%; the concentration of sodium alginate is 1.5 to 2 g / 100 mL; the concentration of trisodium citrate is 1.47 to 2.94 g / 100 mL, and the concentration of citric acid is 1.05 to 2.1 g / 100 mL; in solution B, the concentration of copper sulfate pentahydrate is 30 to 37 g / 100 mL, the concentration of trisodium citrate is 1.47 to 2.94 g / 100 mL, and the concentration of citric acid is 1.05 to 2.1 g / 100 mL.

[0012] In a preferred embodiment of the present invention, in solution A, the mass concentration of hydrogen peroxide is 3.5%; the concentration of sodium alginate is 2 g / 100 mL; the concentration of trisodium citrate is 1.47 g / 100 mL, and the concentration of citric acid is 1.05 g / 100 mL; in solution B, the concentration of copper sulfate pentahydrate is 35 g / 100 mL, the concentration of trisodium citrate is 1.47 g / 100 mL, and the concentration of citric acid is 1.05 g / 100 mL.

[0013] In one embodiment of the present invention, in step 2), the volume ratio of solution A to solution B is 1:2.

[0014] The second technical problem solved by the present invention is to provide a floating copper-loaded sodium alginate hydrogel ball.

[0015] The floating copper-loaded sodium alginate hydrogel ball of the present invention is prepared by the above method. The floating copper-loaded sodium alginate hydrogel ball is a new type of copper-based floating slow-release agent that can be sustained for a long time, which can float on the water surface and release copper ions in a low dose for a long time. Compared with traditional copper-based algaecides, the floating slow-release agent can continuously kill blue algae on the water surface, which can greatly reduce the risk of water pollution caused by excessive copper ion administration, and also reduce the labor cost caused by long-term administration of algaecides.

[0016] The present invention also provides application of the floating copper-loaded sodium alginate hydrogel ball of the present invention in controlling blue algae blooms.

[0017] The buoyant copper-loaded sodium alginate hydrogel ball of the present invention can be used to treat blue algae blooms, and its slow-release effect can effectively reduce the number of times the algaecide is put in, while having little impact on the water body. In addition, the buoyant copper-loaded sodium alginate hydrogel ball of the present invention is buoyant, which is conducive to recycling and will not cause secondary pollution to the water body.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention prepares a novel buoyant copper-loaded sodium alginate hydrogel ball through a specific preparation method. The hydrogel ball can float on the water surface and release copper ions at a low dose for a long time, continuously kill blue algae on the water surface, have little impact on the water body, and can greatly reduce the risk of water pollution caused by excessive copper ion addition; at the same time, it can effectively reduce the number of algaecides, and also reduce the labor cost caused by long-term algaecide addition. The hydrogel ball can float on the water surface for easy recovery, and will not cause secondary pollution to the water body. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The morphological diagram of the floating copper-loaded sodium alginate hydrogel spheres prepared in Examples 1 and 2 of the present invention, wherein the left side is the floating copper-loaded sodium alginate hydrogel spheres prepared in Example 1, and the right side is the floating copper-loaded sodium alginate hydrogel spheres prepared in Example 2.

[0020] Figure 2 The Cu content of the floating copper-loaded sodium alginate hydrogel balls prepared in Examples 1 and 2 of the present invention in pure water is 2+ Unleashing capabilities graph.

[0021] Figure 3 This is a diagram showing the effect of different concentrations of hydrogen peroxide on the gas production and floating of sodium alginate gel balls in Example 4, wherein the concentrations of hydrogen peroxide from left to right are 3%, 3.5%, and 4%, respectively.

[0022] Figure 4 This is a graph showing the changes in chlorophyll and copper content over time in the hydrogel ball algae inhibition experiment in Example 5. DETAILED DESCRIPTION

[0023] The preparation method of the floating copper-loaded sodium alginate hydrogel sphere of the present invention comprises the following steps: 1) preparing solution A and solution B, wherein solution A consists of sodium alginate, citrate, an acidic pH regulator, hydrogen peroxide and water; solution B consists of copper sulfate pentahydrate, citrate, an acidic pH regulator and water; 2) Add solution A dropwise into solution B, stir during the addition, and let stand after the addition is complete to obtain hydrogel spheres; 3) The hydrogel balls are filtered out and the copper sulfate on the surface is removed by washing to obtain floating copper-loaded sodium alginate hydrogel balls.

[0024] The method of the invention is simple and easy to operate, has low raw material cost, and can successfully prepare floating copper-loaded sodium alginate hydrogel balls with sustained-release function.

[0025] In one embodiment of the present invention, in step 1), the citrate is trisodium citrate or copper citrate; and the acidic pH regulator is citric acid.

[0026] In one embodiment of the present invention, in step 1), the citrate is trisodium citrate; and the acidic pH regulator is citric acid.

[0027] The copper sulfate of the present invention is copper sulfate pentahydrate, the trisodium citrate is trisodium citrate dihydrate, and the citric acid is citric acid monohydrate.

[0028] Among them, copper sulfate pentahydrate is the main active ingredient, which is used to release copper ions in water; trisodium citrate reacts in the sodium alginate microenvironment to generate copper citrate to reduce the release rate of copper ions in the gel ball; citric acid adjusts the pH in the sodium alginate microenvironment; sodium alginate is used to form a gel ball by complexing with copper ions; hydrogen peroxide is used to decompose and produce gas in the gel ball to make the gel ball float. Through the mutual cooperation of various substances, a floating type and copper-loaded sodium alginate hydrogel ball with good sustained release function is finally obtained. If other substances that can decompose and produce gas are used to replace hydrogen peroxide, for example, when sodium bicarbonate is used, citric acid monohydrate cannot be added to the sodium alginate solution, which will make the microenvironment in the gel ball alkaline, which is easy to cause copper ions to react to generate copper hydroxide and basic copper carbonate, which is not conducive to the release of copper ions. At the same time, the gas-producing component in the gel ball is carbon dioxide, which has good water solubility, and the floating time of the gel ball will be shortened, affecting its floating performance.

[0029] In one embodiment of the present invention, in solution A of step 1), the mass concentration of hydrogen peroxide is 1% to 4%; the concentration of sodium alginate is 0.5 to 2.5 g / 100 mL; the concentration of trisodium citrate is 0.74 to 5.88 g / 100 mL, and the concentration of citric acid is 0.53 to 4.2 g / 100 mL; in solution B, the concentration of copper sulfate pentahydrate is 5 to 37 g / 100 mL, the concentration of trisodium citrate is 0.74 to 5.88 g / 100 mL, and the concentration of citric acid is 0.53 to 4.2 g / 100 mL.

[0030] In a preferred embodiment of the present invention, in solution A, the mass concentration of hydrogen peroxide is 3% to 4%; the concentration of sodium alginate is 1.5 to 2 g / 100 mL; the concentration of trisodium citrate is 1.47 to 2.94 g / 100 mL, and the concentration of citric acid is 1.05 to 2.1 g / 100 mL; in solution B, the concentration of copper sulfate pentahydrate is 30 to 37 g / 100 mL, the concentration of trisodium citrate is 1.47 to 2.94 g / 100 mL, and the concentration of citric acid is 1.05 to 2.1 g / 100 mL.

[0031] In a preferred embodiment of the present invention, in solution A, the mass concentration of hydrogen peroxide is 3.5%; the concentration of sodium alginate is 2 g / 100 mL; the concentration of trisodium citrate is 1.47 g / 100 mL, and the concentration of citric acid is 1.05 g / 100 mL; in solution B, the concentration of copper sulfate pentahydrate is 35 g / 100 mL, the concentration of trisodium citrate is 1.47 g / 100 mL, and the concentration of citric acid is 1.05 g / 100 mL.

[0032] In one embodiment of the present invention, in step 2), the volume ratio of solution A to solution B is 1:2.

[0033] The floating copper-loaded sodium alginate hydrogel ball of the present invention is prepared by the above method. The floating copper-loaded sodium alginate hydrogel ball is a new type of copper-based floating slow-release agent that can be sustained for a long time, which can float on the water surface and release copper ions in a low dose for a long time. Compared with traditional copper-based algaecides, the floating slow-release agent can continuously kill blue algae on the water surface, which can greatly reduce the risk of water pollution caused by excessive copper ion administration, and also reduce the labor cost caused by long-term administration of algaecides.

[0034] The present invention also provides application of the floating copper-loaded sodium alginate hydrogel ball of the present invention in controlling blue algae blooms.

[0035] The buoyant copper-loaded sodium alginate hydrogel ball of the present invention can be used to treat blue algae blooms, and its slow-release effect can effectively reduce the number of times the algaecide is put in, while having little impact on the water body. In addition, the buoyant copper-loaded sodium alginate hydrogel ball of the present invention is buoyant, which is conducive to recycling and will not cause secondary pollution to the water body.

[0036] The specific implementation modes of the present invention are further described below in conjunction with embodiments, but the present invention is not limited to the scope of the embodiments.

[0037] Example 1 Weigh 10 g of 30% hydrogen peroxide solution, add 90 g of water to dilute it to make 100 g of 3.0% hydrogen peroxide solution, then add 1.47 g (5 mmol) of trisodium citrate dihydrate and 1.05 g (5 mmol) of citric acid monohydrate to the hydrogen peroxide solution and stir to dissolve, finally add 2 g of sodium alginate and stir to dissolve to obtain solution A for standby use.

[0038] Weigh 10 g of copper sulfate pentahydrate, 2.94 g of trisodium citrate dihydrate, and 2.1 g of citric acid monohydrate, and dissolve them in 200 g of water to obtain solution B for later use.

[0039] Solution A was added dropwise into solution B, with slow stirring, to obtain floating hydrogel spheres. After the addition of solution A was completed, stirring was stopped and the solution was allowed to stand for 2 h to allow for full complexation.

[0040] The hydrogel spheres were filtered out and washed three times with 600 mL ultrapure water to remove the copper sulfate solution on the surface, and the final floating copper-loaded sodium alginate hydrogel spheres were obtained. Figure 1 .

[0041] Example 2 Weigh 10 g of 30% hydrogen peroxide solution, add 90 g of water to dilute it to make 100 g of 3.0% hydrogen peroxide solution, then add 1.47 g (5 mmol) of trisodium citrate dihydrate and 1.05 g (5 mmol) of citric acid monohydrate to the hydrogen peroxide solution and stir to dissolve, finally add 2 g of sodium alginate and stir to dissolve to obtain solution A for standby use.

[0042] Weigh 70 g of copper sulfate pentahydrate, 2.94 g of trisodium citrate dihydrate, and 2.1 g of citric acid monohydrate, and dissolve them in 200 g of water to obtain solution B for later use.

[0043] Solution A was added dropwise into solution B, with slow stirring, to obtain floating hydrogel spheres. After the addition of solution A was completed, stirring was stopped and the solution was allowed to stand for 2 h to allow for full complexation.

[0044] The hydrogel spheres were filtered out and washed three times with 600 mL ultrapure water to remove the copper sulfate solution on the surface, and the final floating copper-loaded sodium alginate hydrogel spheres were obtained. Figure 1 .

[0045] Figure 1 In the figure, the left side shows the floating copper-loaded sodium alginate hydrogel spheres prepared in Example 1 (i.e., the low concentration group), and the right side shows the floating copper-loaded sodium alginate hydrogel spheres prepared in Example 2 (i.e., the high concentration group). Figure 1 It can be seen that in the same period of time, the sodium alginate gel spheres chelated under high concentration copper sulfate conditions are darker in color, indicating that they carry more copper ions.

[0046] Take 0.5 g of the floating copper-loaded sodium alginate hydrogel balls prepared in Example 1 and Example 2, respectively, soak them in 500 g of ultrapure water, and monitor the Cu 2+ The concentration changes, the results are shown in Figure 2 .

[0047] from Figure 2 It can be seen that the initial Cu 2+ The concentration and the concentration released within one day were both greater than the hydrogel complexed at a low concentration, so the final concentration of copper sulfate solution was determined to be 35 g / 100 mL.

[0048] Example 3 Referring to the method of Example 2, only the sodium alginate concentration in solution A was changed to obtain floating copper-loaded sodium alginate hydrogel spheres. The copper ion loading in the gel spheres was calculated by atomic absorption determination of the change in copper ion concentration in the copper sulfate solution. The calculation method is as follows: C1: copper ion concentration in solution B; C2: copper ion concentration in the filtrate obtained after filtering out the hydrogel balls; C3: copper ion concentration in the washing solution obtained after washing the hydrogel spheres; V1: volume of solution B; V2: volume of the filtrate obtained after filtering out the hydrogel spheres; V3: the volume of washing solution obtained after washing the hydrogel spheres; m: the mass of the hydrogel sphere after washing The experimental results are shown in Table 1.

[0049] Table 1 It can be seen that when the sodium alginate concentration is 2.0 g / 100 mL, the copper ion loading capacity of the prepared gel spheres is the highest, so the sodium alginate concentration is preferably set to 2.0 g / 100 mL.

[0050] Example 4 Three concentrations of hydrogen peroxide (3.0%, 3.5%, 4.0%) were used to prepare floating copper-loaded sodium alginate hydrogel spheres. The addition amounts of the other components and the preparation method were the same as in Example 2. The concentration of hydrogen peroxide added was determined by observing the floating of the gel spheres after 2 hours. The effects of three concentrations of hydrogen peroxide on the gas production and floating of sodium alginate gel spheres are shown in Figure 2. Figure 3 .

[0051] from Figure 3 It can be seen that the addition of 3% 30% hydrogen peroxide is not enough to make the gel balls float in water; half of the gel balls can float at a 3.5% addition, and the sinking gel balls can also gradually float up after gradually releasing copper ions and their density decreases; most of the gel balls can float at a 4% addition, but some gel balls produce too much gas and break and sink. Therefore, the final concentration of hydrogen peroxide addition was set at 3.5%.

[0052] Example 5 Take 15 red pots and place them outdoors. Add 8.5 L of algae-turbid water to each pot. The dominant algae species in the water is Microcystis. The 15 pots are divided into three groups. Different masses of hydrogel balls prepared in Example 2 are placed in each group. The blank group does not contain hydrogel balls. 500 mL of water samples are taken out every day and 500 mL of algae-turbid water is newly added. The changes in chlorophyll content and copper ion concentration in each group are monitored every day. The results are shown in Tables 2, 3 and Figure 4 .

[0053] Table 2 Chlorophyll concentration monitoring (unit: ppb) Table 3 Copper ion concentration monitoring (unit: ppm) The experimental results show that all experimental groups have a good inhibitory effect on cyanobacteria, which can last for more than 14 days, and the 0.6 g and 0.8 g groups can inhibit the algae for more than 21 days. The copper ion concentration used in each group did not exceed 1 ppm, and gradually decreased and stabilized during the continuous water exchange process, without causing the problem of excessive copper ion concentration in the water body.

Claims

1. A method for preparing floating copper-loaded sodium alginate hydrogel spheres, characterized in that: The following steps are involved: 1) preparing solution A and solution B, wherein solution A consists of sodium alginate, citrate, an acidic pH regulator, hydrogen peroxide and water; solution B consists of copper sulfate pentahydrate, citrate, an acidic pH regulator and water; 2) Add solution A dropwise into solution B, stir during the addition, and let stand after the addition is complete to obtain hydrogel spheres; 3) The hydrogel balls are filtered out and the copper sulfate on the surface is removed by washing to obtain floating copper-loaded sodium alginate hydrogel balls.

2. The method for preparing the floating copper-loaded sodium alginate hydrogel sphere according to claim 1, characterized in that: In step 1), the citrate is trisodium citrate or copper citrate; and the acidic pH regulator is citric acid.

3. The method for preparing the floating copper-loaded sodium alginate hydrogel sphere according to claim 2, characterized in that: In the solution A of step 1), the mass concentration of hydrogen peroxide is 1% to 4%; the concentration of sodium alginate is 0.5 to 2.5 g / 100 mL; the concentration of trisodium citrate is 0.74 to 5.88 g / 100 mL, and the concentration of citric acid is 0.53 to 4.2 g / 100 mL; In solution B, the concentration of copper sulfate pentahydrate is 5 to 37 g / 100 mL, the concentration of trisodium citrate is 0.74 to 5.88 g / 100 mL, and the concentration of citric acid is 0.53 to 4.2 g / 100 mL.

4. The method for preparing the floating copper-loaded sodium alginate hydrogel sphere according to claim 3, characterized in that: In solution A, the mass concentration of hydrogen peroxide is 3% to 4%; the concentration of sodium alginate is 1.5 to 2 g / 100 mL; the concentration of trisodium citrate is 1.47 to 2.94 g / 100 mL, and the concentration of citric acid is 1.05 to 2.1 g / 100 mL; In solution B, the concentration of copper sulfate pentahydrate is 30-37 g / 100 mL, the concentration of trisodium citrate is 1.47-2.94 g / 100 mL, and the concentration of citric acid is 1.05-2.1 g / 100 mL.

5. The method for preparing the floating copper-loaded sodium alginate hydrogel sphere according to claim 4, characterized in that: In solution A, the mass concentration of hydrogen peroxide is 3.5%; the concentration of sodium alginate is 2 g / 100 mL; the concentration of trisodium citrate is 1.47 g / 100 mL, and the concentration of citric acid is 1.05 g / 100 mL; In solution B, the concentration of copper sulfate pentahydrate is 35 g / 100 mL, the concentration of trisodium citrate is 1.47 g / 100 mL, and the concentration of citric acid is 1.05 g / 100 mL.

6. The method for preparing the floating copper-loaded sodium alginate hydrogel sphere according to claim 1, characterized in that: In step 2), the volume ratio of solution A to solution B is 1:

2.

7. Floating copper-loaded sodium alginate hydrogel spheres prepared by the method for preparing floating copper-loaded sodium alginate hydrogel spheres according to any one of claims 1 to 6.

8. Use of the buoyant copper-loaded sodium alginate hydrogel spheres according to claim 7 in controlling blue algae blooms.

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