Repairing agent and repairing method for repairing heavy metal polluted solution by strengthening enzymatic phosphate precipitation under acid rain condition

Abstract

The invention discloses a repairing agent for repairing a heavy metal polluted solution by strengthening enzymatic phosphate precipitation under an acid rain condition, the repairing agent comprises sodium alginate, phytase and sodium glycerophosphate, and the mass ratio of the sodium alginate to the phytase to the sodium glycerophosphate is (1-3): (2-5): 50. The invention further discloses a method for repairing a heavy metal polluted solution by adopting the repairing agent. The repairing agent disclosed by the invention has the characteristic of higher enzyme activity when being applied under an acid rain condition, phosphate ions required by phosphate precipitation can be formed, and the repairing agent is remarkably beneficial to strengthening the stability of the precipitation; the heavy metal ions are adsorbed through functional groups carried on the surface of sodium alginate, removal of the heavy metal ions in the solution is accelerated, the risk of migration and diffusion of the heavy metal ions can be greatly reduced, and favorable conditions are created for improving the curing efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of geotechnical engineering, and particularly relates to a repair agent and a repair method for strengthening enzyme-induced phosphate precipitation to repair heavy metal-polluted solution under acid rain conditions. Background Art

[0002] With the rapid development of social economy, the sewage discharge from factory smelting has brought serious heavy metal pollution to the surrounding soil and water bodies, and the formation of acid rain under the action of environmental pollution has further aggravated the above phenomenon. Previous pollution repairs only focused on improving the repair efficiency, and rarely mentioned improving the repair efficiency and stability under acidic conditions. Traditional repair methods can be divided into: physical methods, chemical methods, and biological methods. The biological repair method has become a hot topic in recent repair methods due to its green, environmental protection, and economic cost. In biological methods, there have been many studies on MIPP (microbially induced phosphate precipitation) and EIPP (enzyme-induced phosphate precipitation) technologies. For example, the invention patent with the patent number CN202311607687.0 proposes "a method for repairing heavy metal pollution", which uses Bacillus megaterium combined with sodium glycerophosphate to induce phosphate precipitation to repair copper ion pollution in water; the invention patent with the patent number CN202311612007.4 proposes "a method and a repair device for enzyme-promoted phosphate to repair heavy metal-polluted loess", which is used to repair heavy metal copper pollution in loess; the invention patent with the patent number CN202310179908.2 proposes "an enzyme-induced phosphate precipitation curing agent and its application method", which is used to reduce the risk of migration and diffusion of heavy metal copper ions in water. However, the activity of the enzyme will decrease under acidic conditions, thereby reducing the curing efficiency of copper ions. In addition, the precipitate generated by the traditional EICP (enzyme-induced carbonate precipitation) technology (for example, the patent number: CN202310176634.1) is easily soluble under acidic conditions, increasing the probability of migration and diffusion of copper ions. In addition, high concentrations of copper ions can also cause the enzyme to denature or even lose its activity, which is not conducive to the repair of heavy metal-polluted water bodies. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a repair agent and a repair method for strengthening enzyme-induced phosphate precipitation to repair heavy metal-polluted solution under acid rain conditions in view of the above-mentioned deficiencies of the prior art. The phosphate precipitate formed after repair has higher chemical stability compared with the traditional EICP (enzyme-induced carbonate precipitation) technology, is not easily soluble under acid rain conditions, and greatly reduces the risk of increasing the migration and diffusion of heavy metal ions due to the instability of the precipitate.

[0004] To solve the above technical problems, the technical solution adopted by the present invention is as follows: A repair agent for strengthening enzymatic phosphate precipitation to repair heavy metal-polluted solution under acid rain conditions, characterized in that the repair agent includes sodium alginate, phytase, and sodium glycerophosphate, and the mass ratio of sodium alginate, the mass of phytase, and the amount of substance of sodium glycerophosphate is (1-3):(2-5):50, where the unit of mass is g and the unit of amount of substance is mmol.

[0005] The above-mentioned repair agent for strengthening enzymatic phosphate precipitation to repair heavy metal-polluted solution under acid rain conditions is characterized in that the mass ratio of sodium alginate, the mass of phytase, and the amount of substance of sodium glycerophosphate is 2:3:50.

[0006] Furthermore, the present invention provides a method for repairing heavy metal-polluted solution using the above-mentioned repair agent, characterized in that it includes adding a sodium glycerophosphate solution, a purified sodium alginate solution, and a phytase solution treated for stability into the heavy metal-polluted solution to obtain a repair system, and allowing the repair system to stand still to complete the repair.

[0007] The above-mentioned method is characterized by including the following steps:

[0008] Step 1. Preparation of sodium glycerophosphate solution: Dissolve sodium glycerophosphate in deionized water to obtain a sodium glycerophosphate solution with a concentration of 200 mmol / L - 300 mmol / L;

[0009] Step 2. Purification of sodium alginate solution: Dissolve sodium alginate in deionized water, stir to dissolve to obtain a sodium alginate solution with a concentration of 5 g / L - 15 g / L, stand still, centrifuge to remove insoluble impurities, collect the clarified liquid after centrifugation, sterilize and store it to obtain a purified sodium alginate solution;

[0010] Step 3. Stability treatment of phytase solution: Dissolve high-temperature-resistant phytase powder in deionized water, stir to dissolve to obtain a phytase solution with a concentration of 10 g / L - 20 g / L, stand still, centrifuge, and then store the centrifuged phytase solution in a buffer solution with pH = 6.5 to maintain the enzyme activity to obtain a phytase solution treated for stability;

[0011] Step 4. Add the sodium glycerophosphate solution in Step 1, the purified sodium alginate solution in Step 2, and the phytase solution treated for stability in Step 3 into the heavy metal-polluted solution eroded by acid rain to obtain a repair system, and stand still for 24 h - 48 h to complete the repair.

[0012] The above-mentioned method is characterized in that the stirring time in Step 2 is 20 min - 45 min.

[0013] The above method is characterized in that in step two, the centrifugation speed is 6000 rpm to 8000 rpm, and the centrifugation time is 8 min to 12 min.

[0014] The above method is characterized in that in step three, the stirring time is 15 min to 30 min.

[0015] The above method is characterized in that in step three, the centrifugation speed is 5000 rpm to 6000 rpm, and the centrifugation time is 4 min to 8 min.

[0016] The above method is characterized in that in step four, the molar ratio of sodium glycerophosphate to heavy metal ions in the heavy metal contaminated solution is 50:(5 - 50).

[0017] The present invention has the following advantages compared with the prior art:

[0018] 1. The repair agent of the present invention includes sodium alginate. The surface of sodium alginate can provide nucleation sites for enzyme - catalyzed phosphate precipitation, and finally form a relatively dense, rod - shaped or block - shaped stable precipitation product, which is not easily soluble in an acidic environment. At the same time, sodium alginate can delay the toxic effect of heavy metal ions on phytase, enabling phytase to efficiently catalyze the decomposition of the substrate sodium glycerophosphate and release phosphate ions. Sufficient phosphate ions combine with heavy metal ions to form heavy metal phosphate precipitates, thus achieving efficient repair. By adsorbing heavy metal ions through the functional groups carried on the surface of sodium alginate, the removal of heavy metal ions in the solution is accelerated. This not only greatly reduces the risk of heavy metal ion migration and diffusion but also creates favorable conditions for improving the solidification efficiency.

[0019] 2. The repair agent of the present invention has the characteristics of high enzyme activity, stable mineralization products, and resistance to acid rain erosion compared with the traditional enzyme - catalyzed phosphate precipitation technology. When applied under acid rain conditions, it has the characteristic of higher enzyme activity. In this way, it can form phosphate ions required for phosphate precipitation, which significantly helps to strengthen the stability of the precipitation, reduce the desorption of heavy metal ions under acid rain conditions and thus reduce the risk of heavy metal migration and diffusion. The heavy metal solidification rate can reach up to 100%, having the characteristics of reducing the risk of pollution migration and diffusion and achieving efficient repair.

[0020] 3. The phosphate precipitate formed after repairing by the method of the present invention has higher chemical stability compared with the traditional EICP (enzyme - induced carbonate precipitation) technology, is not easily soluble under acid rain conditions, and greatly reduces the risk of increasing heavy metal ion migration and diffusion due to unstable precipitation.

[0021] 4. The repair method of the present invention has the characteristics of simple operation steps, easy availability of materials, low cost, and environmental friendliness.

[0022] The following further describes in detail the technical solutions of the present invention in conjunction with the accompanying drawings and embodiments. Description of the Drawings

[0023] Figure 1 It is a phytase activity graph for Example 16 and Comparative Example 4.

[0024] Figure 2 It is a graph of the phosphorus solubilizing ability of the repair agent of the present invention and the repair agent of the comparative example at different pH values.

[0025] Figure 3 It is a graph of the change of copper ion repair efficiency over time for Comparative Examples 1-3 and Examples 1-15 of the present invention.

[0026] Figure 4 It is a graph of the change of lead ion repair efficiency over time. Detailed Embodiments

[0027] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific embodiments of the present invention is made in conjunction with the embodiments. Unless otherwise specified, the technical means used in the following embodiments are conventional means well-known to those skilled in the art. The materials, reagents, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0028] The heavy metal contaminated solutions in the following Examples 1-15 are copper contaminated solutions, which are prepared by dissolving copper nitrate crystals in deionized water to form a 200 mmol / L copper nitrate solution.

[0029] Example 1

[0030] The repair agent for strengthening enzymatic phosphate precipitation to repair copper contaminated solution under acid rain conditions in this example includes sodium alginate, phytase, and sodium glycerophosphate. The mass ratio of sodium alginate, the mass of phytase, and the amount of substance of sodium glycerophosphate is 2:3:50, where the unit of mass is g and the unit of amount of substance is mmol.

[0031] The method for repairing copper contaminated solution using the repair agent of this example includes the following steps:

[0032] Step 1: Preparation of sodium glycerophosphate solution: Accurately weigh sodium glycerophosphate according to the molecular weight of 216.04 and dissolve it in deionized water to obtain a sodium glycerophosphate solution with a concentration of 250 mmol / L;

[0033] Step 2: Purification of sodium alginate solution: Take commercially available sodium alginate (C 6 H 7 NaO 6 ) n, dissolve it in deionized water, stir and dissolve for 30 min to obtain a sodium alginate solution with a concentration of 10 g / L. Let it stand at room temperature for 15 min, take the supernatant and centrifuge it at 8000 rpm for 8 min to remove insoluble impurities. Collect the clarified solution after centrifugation, sterilize it and store it to obtain a purified sodium alginate solution;

[0034] Step 3. Stability treatment of the phytase solution: Dissolve the commercially available high-temperature-resistant phytase powder (active ingredient 40%, Ningxia Xiasheng Industrial Group) in deionized water, stir and dissolve for 20 min to obtain a phytase solution with a concentration of 15 g / L. Let it stand for 15 min, centrifuge it at 6000 rpm for 4 min, and then store the centrifuged phytase solution in a buffer solution with pH = 6.5 to maintain the enzyme activity, obtaining a phytase solution after stability treatment;

[0035] Step 4. Add 4 mL of the sodium glycerophosphate solution in Step 1, 4 mL of the purified sodium alginate solution in Step 2, and 4 mL of the phytase solution after stability treatment in Step 3 to 0.5 mL of a copper nitrate solution with a concentration of 200 mmol / L, make the volume up to 20 mL, and then adjust the pH to 3 to simulate the acid rain condition to obtain a repair system. Let it stand for 48 h to complete the repair, and the copper repair efficiency is 100%.

[0036] Example 2

[0037] This example is the same as Example 1, except that in Step 4, 1 mL of copper nitrate solution is added to make the copper concentration in the repair system 10 mmol / L, and the copper repair efficiency is 100%.

[0038] Example 3

[0039] This example is the same as Example 1, except that in Step 4, 3 mL of copper nitrate solution is added to make the copper concentration in the repair system 30 mmol / L, and the copper repair efficiency is 100%.

[0040] Example 4

[0041] This example is the same as Example 1, except that in Step 4, 4 mL of copper nitrate solution is added to make the copper concentration in the repair system 40 mmol / L, and the copper repair efficiency is 100%.

[0042] Example 5

[0043] This example is the same as Example 1, except that in Step 4, 5 mL of copper nitrate solution is added to make the copper concentration in the repair system 50 mmol / L, and the copper repair efficiency is 100%.

[0044] Example 6

[0045] The remediator for strengthening enzymatic phosphate precipitation to repair copper - polluted solution under acid - rain conditions in this embodiment includes sodium alginate, phytase, and sodium glycerophosphate. The ratio of the mass of sodium alginate, the mass of phytase, and the amount of substance of sodium glycerophosphate is 1:2:50, where the unit of mass is g and the unit of amount of substance is mmol.

[0046] The method for repairing copper - polluted solution using the remediator of this embodiment includes the following steps:

[0047] Step 1: Preparation of sodium glycerophosphate solution: Weigh sodium glycerophosphate accurately according to the molecular weight of 216.04, dissolve it in deionized water to obtain a sodium glycerophosphate solution with a concentration of 200 mmol / L.

[0048] Step 2: Purification of sodium alginate solution: Take commercially available sodium alginate (C 6 H 7 NaO 6 ) n , dissolve it in deionized water, stir and dissolve for 20 min to obtain a sodium alginate solution with a concentration of 5 g / L. Let it stand at room temperature for 15 min, take the supernatant and centrifuge it at 6000 rpm for 12 min to remove insoluble impurities. Collect the centrifuged clear liquid, sterilize it and store it to obtain a purified sodium alginate solution.

[0049] Step 3: Stability treatment of phytase solution: Dissolve commercially available high - temperature - resistant phytase powder (active ingredient 40%, Ningxia Xiasheng Industrial Group) in deionized water, stir and dissolve for 15 min to obtain a phytase solution with a concentration of 10 g / L. Let it stand for 15 min, centrifuge it at 5000 rpm for 8 min, and then store the centrifuged phytase solution in a buffer solution with pH = 6.5 to maintain the enzyme activity, obtaining a phytase solution after stability treatment.

[0050] Step 4: Add 5 mL of the sodium glycerophosphate solution in Step 1, 4 mL of the purified sodium alginate solution in Step 2, and 4 mL of the phytase solution after stability treatment in Step 3 to 0.5 mL of a copper nitrate solution with a concentration of 200 mmol / L, make up the volume to 20 mL, and then adjust the pH to 4 to simulate acid - rain conditions to obtain a repair system. Let it stand for 24 h to complete the repair, and the copper repair efficiency is 100%.

[0051] Example 7

[0052] This example is the same as Example 6, except that in Step 4, 1 mL of copper nitrate solution is added, so that the copper concentration in the repair system is 10 mmol / L, and the copper repair efficiency is 100%.

[0053] Example 8

[0054] This example is the same as Example 6, except that in Step 4, 3 mL of copper nitrate solution is added to make the copper concentration in the repair system 30 mmol / L and the copper repair efficiency 100%.

[0055] Example 9

[0056] This example is the same as Example 6, except that in Step 4, 4 mL of copper nitrate solution is added to make the copper concentration in the repair system 40 mmol / L and the copper repair efficiency 100%.

[0057] Example 10

[0058] This example is the same as Example 6, except that in Step 4, 5 mL of copper nitrate solution is added to make the copper concentration in the repair system 50 mmol / L and the copper repair efficiency 100%.

[0059] Example 11

[0060] The repair agent for strengthening enzymatic phosphate precipitation to repair copper-polluted solution under acid rain conditions in this example includes sodium alginate, phytase, and sodium glycerophosphate. The mass ratio of sodium alginate, phytase, and the amount of substance of sodium glycerophosphate is 3:5:50, where the unit of mass is g and the unit of amount of substance is mmol.

[0061] The method for repairing copper-polluted solution using the repair agent of this example includes the following steps:

[0062] Step 1: Preparation of sodium glycerophosphate solution: Weigh sodium glycerophosphate accurately according to the molecular weight of 216.04 and dissolve it in deionized water to obtain a sodium glycerophosphate solution with a concentration of 300 mmol / L.

[0063] Step 2: Purification of sodium alginate solution: Take commercially available sodium alginate (C 6 H 7 NaO 6 ) n , dissolve it in deionized water, stir and dissolve for 45 min to obtain a sodium alginate solution with a concentration of 15 g / L. Let it stand at room temperature for 15 min, take the supernatant and centrifuge it at 7000 rpm for 10 min to remove insoluble impurities, collect the centrifuged clear liquid, sterilize it and store it to obtain a purified sodium alginate solution.

[0064] Step 3. Stability treatment of phytase solution: Dissolve the commercially available heat-resistant phytase powder (active ingredient 40%, Ningxia Xiasheng Industry Group) in deionized water, stir and dissolve for 30 min to obtain a phytase solution with a concentration of 20 g / L, let it stand for 15 min, centrifuge at 5500 rpm for 6 min, and then store the centrifuged phytase solution in a buffer solution with pH = 6.5 to maintain the enzyme activity, obtaining the phytase solution after stability treatment;

[0065] Step 4. Add 3.3 mL of the sodium glycerophosphate solution in Step 1, 4 mL of the purified sodium alginate solution in Step 2, and 5 mL of the phytase solution after stability treatment in Step 3 to 0.5 mL of a copper nitrate solution with a concentration of 200 mmol / L, make up the volume to 20 mL, and then adjust the pH to 5 to simulate the acid rain condition to obtain a repair system, let it stand for 36 h to complete the repair, and the copper repair efficiency is 100%.

[0066] Example 12

[0067] This example is the same as Example 11, except that in Step 4, 1 mL of copper nitrate solution is added, so that the copper concentration in the repair system is 10 mmol / L, and the copper repair efficiency is 100%.

[0068] Example 13

[0069] This example is the same as Example 11, except that in Step 4, 3 mL of copper nitrate solution is added, so that the copper concentration in the repair system is 30 mmol / L, and the copper repair efficiency is 100%.

[0070] Example 14

[0071] This example is the same as Example 11, except that in Step 4, 4 mL of copper nitrate solution is added, so that the copper concentration in the repair system is 40 mmol / L, and the copper repair efficiency is 100%.

[0072] Example 15

[0073] This example is the same as Example 11, except that in Step 4, 5 mL of copper nitrate solution is added, so that the copper concentration in the repair system is 50 mmol / L, and the copper repair efficiency is 100%.

[0074] Example 16

[0075] Determination of the activity of phytase after adding sodium alginate under acidic conditions:

[0076] Step 1. Preparation of reaction system

[0077] Add 10 g / L sodium alginate solution (volume: 4 mL), 15 g / L phytase solution (volume: 4 mL), and 250 mmol / L sodium glycerophosphate solution (volume: 0.4 mL) into a test tube in sequence. Then, use distilled water to make the volume of the mixture up to 20 mL to form an initial reaction system.

[0078] Step 2: pH Regulation and Activity Determination

[0079] Adjust the volume-fixed solution to the target pH values (3, 4, 5) with 0.5 mol / L HCl solution, and let it stand for reaction at room temperature for 30 min. After centrifugation, take the supernatant and determine the phosphate concentration by molybdenum antimony anti-spectrophotometry. The phytase activity is calculated according to the formula: UA == y / (m × t) × n, where UA is the phytase activity, with the unit of (U / mg), y is the amount of phosphate calculated from the absorbance value of the actual sample solution by the linear regression equation, with the unit of (μmol), t is the reaction time, with the unit of (min), n is the dilution factor, and m is the amount of phytase, with the unit of (g).

[0080] Comparative Example 1

[0081] This comparative example uses the phytase solution, sodium glycerophosphate solution, and copper nitrate solution prepared in Example 1, without adding sodium alginate. Mix 15 g / L phytase solution (4 mL), 250 mmol / L sodium glycerophosphate (4 mL), and copper nitrate solution, and adjust the pH to 3 after making the volume up to 20 mL to obtain a repair system. Let it stand for 48 h to complete the repair. The addition amounts of the copper nitrate solution are 0.5 mL, 1 mL, 3 mL, 4 mL, and 5 mL, and the highest copper repair efficiency is 69.02%.

[0082] Comparative Example 2

[0083] This comparative example uses the phytase solution, sodium glycerophosphate solution, and copper nitrate solution prepared in Example 6, without adding sodium alginate. Mix 10 g / L phytase solution (4 mL), 200 mmol / L sodium glycerophosphate (5 mL), and copper nitrate solution, and adjust the pH to 4 after making the volume up to 20 mL to obtain a repair system. Let it stand for 48 h to complete the repair. The addition amounts of the copper nitrate solution are 0.5 mL, 1 mL, 3 mL, 4 mL, and 5 mL, and the highest copper repair efficiency is 68.97%.

[0084] Comparative Example 3

[0085] This comparative example uses the phytase solution, sodium glycerophosphate solution, and copper nitrate solution prepared in Example 11, without adding sodium alginate. 20 g / L phytase solution (5 mL), 300 mmol / L sodium glycerophosphate (3.3 mL) were mixed with the copper nitrate solution, and the volume was fixed to 20 mL and then the pH was adjusted to 5 to obtain a repair system, which was allowed to stand for 48 h to complete the repair. The addition amounts of the copper nitrate solution were 0.5 mL, 1 mL, 3 mL, 4 mL, and 5 mL, and the highest copper repair efficiency was 75.29%.

[0086] Comparative Example 4

[0087] This comparative example measures the activity of phytase without adding sodium alginate under acidic conditions:

[0088] Step 1. Preparation of the reaction system

[0089] 15 g / L phytase solution (volume 4 mL) and 250 mmol / L sodium glycerophosphate solution (volume 0.4 mL) were successively added to a test tube, and then the mixture was fixed to 20 mL with distilled water to form an initial reaction system;

[0090] Step 2. pH regulation and activity measurement

[0091] The fixed solution was adjusted to the target pH values (3, 4, 5) with 0.5 mol / L HCl solution, and allowed to stand and react at room temperature for 30 min. After centrifugation, the supernatant was taken, and the phosphate concentration was measured by the molybdenum antimony anti-spectrophotometry method. The phytase activity was calculated according to the formula: UA == y / (m×t)×n, where UA is the phytase activity, in units of (U / mg), y is the amount of phosphate calculated from the absorbance value of the actual sample solution by the linear regression equation, in units of (μmol), t is the reaction time, in units of (min), n is the dilution factor, and m is the amount of phytase, in units of (g).

[0092] Performance evaluation

[0093] Figure 1 Figure 25 shows the phytase activity diagrams of Example 16 and Comparative Example 4. It can be observed from the figure that the activity of phytase shows an upward trend with the increase of pH. It can be seen that the activity of phytase is inhibited in a strong acid environment. This is because in a strong acid environment, the molecular structure of phytase is partially damaged, losing a part of its enzyme activity. From Figure 1 it can be seen that the activity and phosphorus solubilizing ability of phytase are better in a weak acid environment than in a strong acid environment. After adding sodium alginate, its activity can be increased to 2.8 U / mg, while the highest enzyme activity without adding sodium alginate is only 2.2 U / mg. This is because after adding sodium alginate, the gel properties of sodium alginate protect the molecular structure of phytase, thereby increasing the activity of phytase.

[0094] Figure 2 This is a graph showing the phosphorus - releasing ability of the repair agent of the present invention and the repair agent of the comparative example at different pH values. The results obtained from the determination of phosphorus - releasing ability show that the substrate sodium glycerophosphate (SGP) is continuously decomposed from 0 to 20 h, and phosphate ions are released. The concentration reaches 49 mmol / L after 20 h and there is no significant change thereafter. Since the substrate concentration is set at 50 mmol / L, this indicates that SGP is completely decomposed after 20 h. From Figure 2 It can also be observed that at 10 h, the concentration of phosphate ions is 30 mmol / L under the condition of pH = 3, while the concentration of phosphate ions is 35 mmol / L under the condition of pH = 5. That is to say, although the substrate in all samples is finally completely decomposed, the decomposition rate of the substrate is faster under the condition of high pH value. At the same time, it is observed that the concentration of phosphate ions measured with sodium alginate added under the condition of pH = 3 is 34 mmol / L, which is higher than the concentration of phosphate ions measured without sodium alginate added. Similar situations also occur at pH = 4 and 5, indicating that the phosphorus - releasing ability of phytase is better in the environment with sodium alginate added than without sodium alginate added. At the same time, Figure 2 and Figure 1 correspond to each other. This is because the higher the activity of phytase, the greater the rate of decomposing and catalyzing the substrate, the greater the amount of phosphate ions produced per unit time, and the higher the concentration of phosphate ions.

[0095] Figure 3 This is a graph showing the change of copper - ion repair efficiency with time for the comparative example and the examples of the present invention. Figure 3 a, Figure 3 b, Figure 3 c are the changes of copper repair efficiency with time without sodium alginate added at pH = 3, 4, and 5 respectively. Figure 3 d, Figure 3 e, Figure 3 f are the changes of copper repair efficiency with time with sodium alginate added at pH = 3, 4, and 5 respectively. Under the condition of pH = 3, the lowest copper repair efficiency of the test group without sodium alginate added is 39% at 12 h, while after adding sodium alginate, the repair efficiency increases to 83% at 12 h. Under the condition of pH = 4, the lowest copper repair efficiency of the test group without sodium alginate added is 53% at 12 h, while after adding sodium alginate, the repair efficiency can reach 98% at 12 h. Under the condition of pH = 5, the lowest copper repair efficiency of the test group without sodium alginate added is 64% at 12 h, while after adding sodium alginate, the repair efficiency can reach 100% at 12 h. In addition, the highest copper repair efficiencies without sodium alginate added at pH = 3, 4, and 5 are 67%, 68%, and 75% respectively, while after adding sodium alginate, the repair efficiencies all increase to 100%. The test and calculation methods of the repair efficiency include: centrifuging the system after heavy - metal pollution repair to obtain the supernatant, filtering it with a 0.22 - μm needle - type filter, diluting it with distilled water, and measuring Cu with an atomic absorption spectrophotometer 2+Concentration, where the centrifugation rate can be 4000 - 8000 r / min and the time can be 5 - 15 min.

[0096] Calculate the repair efficiency according to the following formula:

[0097] Copper repair efficiency = [(CI - CR) / CI] × 100%

[0098] Wherein, CI is the initial concentration of Cu 2+ and CR is the remaining concentration of Cu after repair. 2+

[0099] The above description shows that after adding sodium alginate, the copper repair efficiency has been significantly improved. This is because sodium alginate adsorbs copper ions in the solution, slows down the migration rate of copper ions in the solution, and greatly hinders the toxic effect of copper ions on phytase. In addition, sodium alginate can also provide nucleation sites for copper phosphate precipitation, accelerating the repair of copper ions in the solution. It can also be seen from the figure that as the pH decreases, the copper repair rate slows down, while adding sodium alginate can increase the copper repair rate, which is related to Figure 1 the decrease in phytase activity with the decrease in pH and Figure 2 the decrease in the increasing rate of phosphate concentration with the decrease in pH. In addition, it can be seen from Figure 3 that the copper repair efficiency increases with the increase in pH. This result can be expected in the previous analysis of the change of phytase activity with pH. At the same time, it is also observed that the copper repair efficiency gradually increases with the increase in time.

[0100] The methods of Examples 1 - 15 and Comparative Examples 1 - 3 of the present invention were used to repair the lead - contaminated solution respectively. The lead - contaminated solution was a 200 mmol / L lead nitrate solution prepared by dissolving lead nitrate crystals in deionized water. The repair results are shown in Figure 4 .

[0101] Figure 4 a, Figure 4 b, Figure 4 c are the changes of lead repair efficiency with time without adding sodium alginate at pH = 3, 4, and 5 respectively. Figure 4 d, Figure 4 e, Figure 4The changes of the lead repair efficiency with time under the addition of sodium alginate at pH = 3, 4, and 5 are shown respectively. Under the condition of pH = 3, the lead repair efficiency of the test group without sodium alginate was the lowest at 45% at 12 h, while after the addition of sodium alginate, the repair efficiency increased to 74% at 12 h. Under the condition of pH = 4, the lead repair efficiency of the test group without sodium alginate was the lowest at 50% at 12 h, while after the addition of sodium alginate, the repair efficiency reached 80% at 12 h. Under the condition of pH = 5, the lead repair efficiency of the test group without sodium alginate was the lowest at 54% at 12 h, while after the addition of sodium alginate, the repair efficiency reached 76% at 12 h. In addition, the highest lead repair efficiencies without the addition of sodium alginate at pH = 3, 4, and 5 were 65%, 63%, and 66% respectively, while after the addition of sodium alginate, the repair efficiencies all increased to 100%. The test and calculation methods of the repair efficiency are the same as those of the above-mentioned copper repair efficiency.

[0102] In the present invention, phytase catalyzes the hydrolysis of sodium glycerophosphate to release phosphate ions, which form phosphate precipitates with heavy metal ions. Using sodium alginate as a three-dimensional network carrier, the carboxyl complexation enhances the heavy metal adsorption ability. The tests show that the repair agent of the present invention has the following advantages:

[0103] Dual synergistic effect: The synergistic effect of enzymatic precipitation and gel adsorption enables the highest heavy metal removal rate to reach 100%;

[0104] Acid adaptability: The system still maintains high catalytic activity (phytase activity > 1.7 U / mg) at pH = 3;

[0105] Thermal stability: Using heat-resistant phytase (half-life at 70 °C > 2 h), it is suitable for industrial wastewater treatment scenarios.

[0106] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural changes made to the above embodiments according to the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A repair agent for strengthening enzymatic phosphate precipitation to repair heavy metal contaminated solutions under acid rain conditions, characterized in that: The repair agent comprises sodium alginate, phytase and sodium glycerol phosphate, wherein the mass ratio of the sodium alginate, the mass of the phytase and the amount of substance of the sodium glycerol phosphate is (1-3):(2-5):50, wherein the unit of mass is g and the unit of the amount of substance is mmol.

2. The repair agent for strengthening enzymatic phosphate precipitation and repairing heavy metal contaminated solution under acid rain conditions according to claim 1, characterized in that: The mass ratio of the sodium alginate, the mass of the phytase and the amount of sodium glycerophosphate is 2:3:

50.

3. A method for repairing a heavy metal contaminated solution using the repair agent as claimed in claim 1, characterized in that: The method comprises adding sodium glycerophosphate solution, purified sodium alginate solution and phytase solution treated with stability into a heavy metal contaminated solution to obtain a repair system, and placing the repair system to stand to complete the repair.

4. The method according to claim 3, characterized in that The following steps are involved: Step 1, preparation of sodium glycerophosphate solution: dissolving sodium glycerophosphate in deionized water to obtain a sodium glycerophosphate solution with a concentration of 200 mmol / L to 300 mmol / L; Step 2, purification of sodium alginate solution: dissolving sodium alginate in deionized water, stirring and dissolving to obtain a sodium alginate solution with a concentration of 5 g / L to 15 g / L, standing, centrifuging to remove insoluble impurities, collecting the clarified liquid after centrifugation, sterilizing and storing to obtain a purified sodium alginate solution; Step 3, stability treatment of the phytase solution: dissolving the thermostable phytase powder in deionized water, stirring and dissolving to obtain a phytase solution with a concentration of 10 g / L to 20 g / L, standing, centrifuging, and then storing the centrifuged phytase solution in a buffer solution with a pH of 6.5 to maintain enzyme activity, thereby obtaining a phytase solution treated with stability; Step 4: Add the sodium glycerophosphate solution in step 1, the purified sodium alginate solution in step 2, and the stabilization-treated phytase solution in step 3 to the heavy metal-contaminated solution corroded by acid rain to obtain a repair system, and let it stand for 24 to 48 hours to complete the repair.

5. The method according to claim 4, characterized in that The stirring time in step 2 is 20 min to 45 min.

6. The method according to claim 4, characterized in that In step 2, the centrifugal speed is 6000 rpm to 8000 rpm, and the centrifugal time is 8 min to 12 min.

7. The method according to claim 4, characterized in that The stirring time in step 3 is 15 min to 30 min.

8. The method according to claim 4, characterized in that In step 3, the centrifugal speed is 5000 rpm to 6000 rpm, and the centrifugal time is 4 min to 8 min.

9. The method according to claim 4, characterized in that The ratio of the amount of sodium glycerophosphate in step 4 to the amount of heavy metal ions in the heavy metal contaminated solution is 50:(5-50).

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