Modified polyaluminum chloride with high phosphorus removal performance, and preparation method and application thereof

Abstract

The application provides a modified polyaluminum chloride with high phosphorus removal performance and a preparation method and application thereof, and belongs to the technical field of modified polyaluminum chloride. First, aluminum chloride, zirconium oxychloride and an alkaline adjusting agent are reacted in an aqueous phase to prepare an aluminum-zirconium complex mother liquor, then a polyhexamethylene biguanide solution is added to the aluminum-zirconium complex mother liquor, and through electrostatic, coordination and hydrogen bond effects, effective compounding of organic long-chain molecules and inorganic complexes is realized. Finally, a polyol stabilizer, mannitol, is introduced into the organic-inorganic compounding system, and through the chelation effect on the metal center and the steric hindrance effect of the molecule, premature polymerization and precipitation of the product are inhibited. Through the complexation of zirconium ions and the strong electro neutrality of polyhexamethylene biguanide, the removal efficiency of phosphate is improved, the formed flocculating body is more compact, the settling speed is fast, and the application range of the product under complex water quality conditions is widened.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of modified polyaluminum chloride and relates to modified polyaluminum chloride with high phosphorus removal performance and a preparation method and application thereof. BACKGROUND

[0002] Water body eutrophication is increasingly prominent, and one of the main causes is the existence of excessive phosphorus elements in industrial wastewater and domestic sewage. At present, the chemical coagulation method is one of the most widely used and economic and efficient technical means for treating phosphorus-containing wastewater. By adding a chemical coagulant, the phosphates and other pollutants in the water are destabilized, aggregated, and flocculated to form a precipitate, thereby being separated. Among numerous inorganic polymer coagulants, polyaluminum chloride is widely used due to its advantages of less dosage than traditional aluminum salt coagulants and wide applicable pH range.

[0003] However, the traditional polyaluminum chloride has insufficient phosphorus removal performance when dealing with high-concentration phosphorus-containing wastewater, and the coagulation effect is significantly affected under complex water quality conditions such as low temperature and low turbidity. In a low-temperature or weakly alkaline environment, high-valent aluminum hydroxyl complexes are difficult to form rapidly, resulting in the attenuation of charge neutralization and entrapment effect, and the deep phosphorus removal goal is difficult to achieve. SUMMARY

[0004] To solve the above problems, the purpose of the present application is to provide modified polyaluminum chloride with high phosphorus removal performance and a preparation method and application thereof. First, the polyaluminum chloride zirconium mother liquor is prepared by controlling the pH and constant temperature aging. Then, the mother liquor is purified and subjected to organic-inorganic composite reaction with polyhexamethylene biguanide. Finally, mannitol is added to the system for stabilization treatment. Through the synergistic effect of zirconium ions and organic polymer polyhexamethylene biguanide, the phosphorus removal efficiency and flocculation performance of the product are improved, and the application range of the product under complex water quality conditions such as low temperature and low turbidity is widened.

[0005] To achieve this purpose, the following technical solutions are adopted in the present application:

[0006] In a first aspect, the present application provides a preparation method of modified polyaluminum chloride with high phosphorus removal performance, which comprises:

[0007] Step (1): adding aluminum chloride, zirconium oxychloride, and spherical calcium carbonate into deionized water to obtain a first reaction liquid, and then adding a sodium carbonate solution to adjust the pH of the first reaction liquid and constant temperature aging to obtain a second reaction liquid;

[0008] Step (2): filtering the second reaction liquid after cooling, and then adding a polyhexamethylene biguanide solution to the obtained filtrate for constant temperature stirring reaction to obtain a third reaction liquid;

[0009] Step (3): adding mannitol into the third reaction solution and dispersing uniformly to obtain a treatment solution, and adding deionized water to stir and filter to obtain modified polyaluminum chloride with high phosphorus removal performance.

[0010] As a preferred technical solution of the present application, in step (1), the molar ratio of aluminum chloride to zirconium oxychloride is 1:(0.04-0.06), for example, it can be 1:0.04, 1:0.042, 1:0.044, 1:0.046, 1:0.048, 1:0.050, 1:0.052, 1:0.054, 1:0.056, 1:0.058 or 1:0.06, but not limited to the listed values, other values not listed in this range are also applicable.

[0011] In some optional embodiments, the mass ratio of aluminum chloride to spherical calcium carbonate is 1:(0.08-0.12), for example, it can be 1:0.08, 1:0.084, 1:0.088, 1:0.092, 1:0.096, 1:0.100, 1:0.104, 1:0.108, 1:0.112, 1:0.116 or 1:0.12, but not limited to the listed values, other values not listed in this range are also applicable.

[0012] In some optional embodiments, the concentration of aluminum chloride in the first reaction solution is 2-3M, for example, it can be 2.0M, 2.1M, 2.2M, 2.3M, 2.4M, 2.5M, 2.6M, 2.7M, 2.8M, 2.9M or 3.0M, but not limited to the listed values, other values not listed in this range are also applicable.

[0013] In some optional embodiments, the concentration of the sodium carbonate solution is 2.5-3.5M, for example, it can be 2.5M, 2.6M, 2.7M, 2.8M, 2.9M, 3.0M, 3.1M, 3.2M, 3.3M, 3.4M or 3.5M, but not limited to the listed values, other values not listed in this range are also applicable.

[0014] In some optional embodiments, the pH of the first reaction solution is adjusted to 3.8-4.0, for example, it can be 3.80, 3.82, 3.84, 3.86, 3.88, 3.90, 3.92, 3.94, 3.96, 3.98 or 4.00, but not limited to the listed values, other values not listed in this range are also applicable.

[0015] In some optional embodiments, the temperature of the constant temperature aging is 60-70℃, for example, it can be or 70℃, but not limited to the listed values, other values not listed in this range are also applicable.

[0016] In some optional embodiments, the isothermal aging time is 2-3 hours, for example, it can be 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, 2.5 hours, 2.6 hours, 2.7 hours, 2.8 hours, 2.9 hours or 3.0 hours, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0017] As a preferred technical solution of the present invention, in step (2), the second reaction solution is cooled to a temperature For example, it can be 30℃, 30.5℃, 31℃, 31.5℃, 32℃, 32.5℃, 33℃, 33.5℃, 34℃, 34.5℃ or 35℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] In some optional embodiments, the concentration of the polyhexamethylene biguanide solution is 0.5-1.0 wt%, for example, it may be 0.50 wt%, 0.55 wt%, 0.60 wt%, 0.65 wt%, 0.70 wt%, 0.75 wt%, 0.80 wt%, 0.85 wt%, 0.90 wt%, 0.95 wt%, or 1.00 wt%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0019] In some optional embodiments, the amount of polyhexamethylene biguanide added is 3-5 wt% of the mass of the second reaction solution, for example, it can be 3.0 wt%, 3.2 wt%, 3.4 wt%, 3.6 wt%, 3.8 wt%, 4.0 wt%, 4.2 wt%, 4.4 wt%, 4.6 wt%, 4.8 wt%, or 5.0 wt%, but is not limited to the values ​​listed, and other unlisted values ​​within this range are also applicable.

[0020] In some optional embodiments, the temperature of the stirring reaction is 45-55°C, for example, it can be... Or 55℃, but not limited to the listed values; other unlisted values ​​within this range also apply.

[0021] In some optional embodiments, the stirring reaction time is 60-70 min, for example, 60 min, 61 min, 62 min, 63 min, 64 min, 65 min, 66 min, 67 min, 68 min, 69 min or 70 min, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0022] As a preferred technical solution of the present application, in step (3), the addition amount of mannitol is 3-4% of the mass of the third reaction solution, for example, it can be 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9% or 4.0%, but is not limited to the listed values, and other unlisted values within the range are also applicable.

[0023] In some optional embodiments, the mass fraction of aluminum oxide in the modified polyaluminum chloride is ≥10%.

[0024] In the second aspect, the present application provides a modified polyaluminum chloride with high phosphorus removal performance.

[0025] In conventional polyaluminum chloride, the aluminum-oxygen nucleus mainly relies on charge neutralization and net capture to remove suspended solids, and has weak complexation with phosphate, and the particles are dense, the dissolution rate is slow, and the amount of sludge generated is large. The present application is modified in view of the above-mentioned deficiencies.

[0026] Firstly, zirconium oxychloride is introduced synchronously in the aluminum hydrolysis-polycondensation stage, and the hybrid nucleus containing Al-O-Zr bond is generated by using the higher Lewis acidity of zirconium atom and the stronger affinity of phosphate. The d atomic orbit of zirconium can form a stable coordination bond with the non-bonding electron pair of phosphate, so that the flocculant not only depends on electrostatic adsorption; at the same time, the high valence state of zirconium improves the positive charge density of the whole nucleus, which is beneficial to fast charge neutralization and primary bonding of flocculation. In the inorganic polymerization stage, aluminum and zirconium hydrolyze to form multi-nuclear hydroxyl complexes through hydroxyl and oxygen bridge action. The phosphorus removal function of the complex comes from two ways: first, the dense distribution of positive charges on the surface of the complex produces electrostatic attraction to the negatively charged phosphate ions in water, which are enriched on the surface of the complex; second, the active hydroxyl groups or water ligands on the surface of the complex can form coordination bonds with phosphate, thereby fixing the phosphate in the form of chemical precipitation. At the same time, the high valence cation complex acts as a coagulant, effectively reducing the negative charge on the surface of colloidal particles in water through electrostatic neutralization, eliminating the electrostatic repulsion between particles, and promoting the instability of small particles and the aggregation into micro-flocs.

[0027] Secondly, spherical calcium carbonate is used as an alkalizer with controllable reaction rate. Its uniform spherical shape and specific specific surface area can achieve slow and uniform dissolution under stirring, thereby smoothly increasing the pH value of the system. Compared with the rapid addition of strong base (such as sodium hydroxide), this mild alkalization method can avoid the precipitation of aluminum hydroxide caused by local high pH, which is conducive to guiding more aluminum ions to generate polymeric forms with high charge and excellent flocculation performance, thereby optimizing the final structure and performance of the polymer.

[0028] Polyhexamethylene biguanide is introduced in the present application, and the rapid coating is realized through the hydrogen bond and electrostatic interaction between the polyguanide cation and the surface of polyaluminum-zirconium core. The guanidine group has the ability to form double hydrogen bond and ion pair with phosphate, which can synergistically enhance the phosphorus removal effect with zirconium-oxygen sites. Polyhexamethylene biguanide is an organic polymer, which contains repeating guanidine units in the molecular backbone. In aqueous solution environment, the guanidine units are protonated, so that the polyhexamethylene biguanide exhibits the characteristics of cationic polyelectrolyte. When mixed with aluminum-zirconium complexes which also carry positive charges, the mutual association is realized through electrostatic interaction, hydrogen bond and coordination. The nitrogen atoms on the molecular chain of polyhexamethylene biguanide have lone pair electrons, which can act as Lewis bases and coordinate with Lewis acid sites (i.e. coordination unsaturated metal centers) on the surface of aluminum-zirconium complexes. At the same time, hydrogen bonds can be formed between hydrogen atoms on the organic polymer and hydroxyl groups or water ligands on the surface of inorganic complexes. In terms of coagulation effect, the long chain structure of polyhexamethylene biguanide simultaneously adsorbs multiple micro-flocs formed by electrical neutralization, forming larger and more compact macro-flocs, which accelerates the settling process of flocs. In terms of phosphorus removal, the positive charges carried by polyhexamethylene biguanide are superimposed on the inorganic core, further enhancing the electrostatic capture ability of the entire composite system for phosphate; at the same time, the positive charge of guanidine group remains stable in a wide pH range, which can compensate for the decrease of aluminum core charge density when the alkalinity is insufficient, ensuring that the flocs are still dense and have high settling speed. The coating is completed by physical adsorption rather than free radical polymerization, avoiding the degradation of guanidine group under high temperature or oxidation conditions, reducing energy consumption and the risk of side reactions.

[0029] In the final product formulation stage, mannitol is added as a complex stabilizer. Mannitol is a polyol, which contains multiple hydroxyl groups in its molecular structure and can act as a polydentate ligand to coordinate with the metal centers on the surface of aluminum-zirconium complexes to form chelates, inhibiting the tendency of further polymerization between complexes. In addition, the mannitol molecules grafted to the surface of inorganic complexes produce a steric hindrance effect due to their own spatial volume. This effect physically hinders the mutual approach and aggregation of each multi-nuclear complex particle, preventing the product from settling or gelling during storage. Subsequently, deionized water is added to adjust to the target concentration, and the final product is a uniform, clear and stable high-performance liquid flocculant after filtration treatment. This liquid form eliminates the complex dissolution process of solid products, and can be directly added for use, responding more quickly and being more convenient to operate.

[0030] In a third aspect, the present application provides a modified polyaluminum chloride with high phosphorus removal performance for application in wastewater treatment.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] By adding zirconium oxychloride in the aluminum hydrolysis-polycondensation process, the zirconium can be embedded into the polyaluminum core to form Al-O-Zr bond. The zirconium provides stable chemical phosphorus capture sites by virtue of high Lewis acidity and d-orbital coordination ability, and improves the core positive charge due to high valence, thereby simultaneously strengthening the phosphorus removal capacity and charge neutralization-flocculation rate.

[0033] In the present application, the polyhexamethylene biguanide coats the aluminum-zirconium core by electrostatic and hydrogen bonds. The long-chain structure of the polyhexamethylene biguanide simultaneously adsorbs multiple micro-flocs formed by the electrical neutralization, accelerates the settling process of the flocs, and the positive charge carried by the polyhexamethylene biguanide itself is superimposed on the inorganic core, further enhancing the electrostatic capture ability of phosphate. The stable positive charge can maintain the floc density and fast settling at low temperature or low alkali, and the coating process does not require high-temperature polymerization, avoiding the degradation of guanidine groups and reducing energy consumption.

[0034] The present application prepares a stable and uniform liquid product, and adds mannitol as a complex stabilizer to further prevent polymerization and settling. The liquid product eliminates the dissolution process of solid flocculants and can be directly added. The active components can be dispersed in water instantly and play a role, with faster response speed. Due to the optimization of polymer morphology and the synergy of multiple phosphorus removal mechanisms, higher phosphorus removal efficiency can be achieved at a lower dosage. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be described in detail below in combination with specific examples. The examples described herein are specific embodiments of the present application, which are used to illustrate the concept of the present application; these descriptions are all explanatory and exemplary, and should not be understood as limiting the embodiments of the present application and the protection scope of the present application. In addition to the examples described herein, those skilled in the art can also employ other technical solutions that are obvious based on the disclosure of the claims and the specification of the present application, which include technical solutions that make any obvious substitutions and modifications to the examples described herein.

[0036] The chemical reagents used in the examples and comparative examples of the present application are all commercially available without further purification or treatment.

[0037] Example 1

[0038] The present embodiment provides a modified polyaluminum chloride with high phosphorus removal performance and a preparation method thereof. The preparation method of the modified polyaluminum chloride with high phosphorus removal performance specifically comprises the following steps:

[0039] Step (1): Add aluminum chloride, zirconium oxychloride, and spherical calcium carbonate to deionized water to obtain the first reaction solution, wherein the molar ratio of aluminum chloride to zirconium oxychloride is 1:0.055, the mass ratio of aluminum chloride to spherical calcium carbonate is 1:0.12, and the concentration of aluminum chloride in the first reaction solution is 2.7M; add sodium carbonate solution with a concentration of 3.2M to adjust the pH of the first reaction solution to 3.9, and then age it at a constant temperature of 60℃ for 2.0h to obtain the second reaction solution;

[0040] Step (2): After cooling the second reaction solution to 34°C, filter it. Add polyhexamethylene biguanide solution to the obtained filtrate and stir the mixture at a constant temperature of 48°C for 68 min to obtain the third reaction solution. The concentration of the polyhexamethylene biguanide solution is 0.65 wt%, and the amount of polyhexamethylene biguanide added is 4.2 wt% of the mass of the second reaction solution.

[0041] Step (3): Add mannitol to the third reaction solution and disperse it evenly to obtain a treatment solution. The amount of mannitol added is 3% of the mass of the third reaction solution. After adding deionized water and stirring thoroughly, filter to obtain modified polyaluminum chloride with high phosphorus removal performance. The mass fraction of alumina in the modified polyaluminum chloride is ≥10%.

[0042] Example 2

[0043] This embodiment provides a modified polyaluminum chloride with high phosphorus removal performance and its preparation method. The preparation method of the modified polyaluminum chloride with high phosphorus removal performance specifically includes the following steps:

[0044] Step (1): Add aluminum chloride, zirconium oxychloride, and spherical calcium carbonate to deionized water to obtain the first reaction solution, wherein the molar ratio of aluminum chloride to zirconium oxychloride is 1:0.04, the mass ratio of aluminum chloride to spherical calcium carbonate is 1:0.10, and the concentration of aluminum chloride in the first reaction solution is 2M; add a 3.5M sodium carbonate solution to adjust the pH of the first reaction solution to 3.8 and then keep it at a constant temperature. The second reaction solution was obtained after aging for 3 hours.

[0045] Step (2): After cooling the second reaction solution to 30°C, filter it. Add polyhexamethylene biguanide solution to the obtained filtrate, and stir the mixture at a constant temperature of 50°C for 70 min to obtain the third reaction solution. The concentration of the polyhexamethylene biguanide solution is 1 wt%, and the amount of polyhexamethylene biguanide added is 3 wt% of the mass of the second reaction solution.

[0046] Step (3): Add mannitol to the third reaction solution and disperse it evenly to obtain a treatment solution, wherein the amount of mannitol added is 4% of the mass of the third reaction solution; add deionized water, stir thoroughly, and filter to obtain modified polyaluminum chloride with high phosphorus removal performance, wherein the mass fraction of alumina in the modified polyaluminum chloride is ≥10%.

[0047] Example 3

[0048] This embodiment provides a modified polyaluminum chloride with high phosphorus removal performance and its preparation method. The preparation method of the modified polyaluminum chloride with high phosphorus removal performance specifically includes the following steps:

[0049] Step (1): Add aluminum chloride, zirconium oxychloride, and spherical calcium carbonate to deionized water to obtain the first reaction solution, wherein the molar ratio of aluminum chloride to zirconium oxychloride is 1:0.06, the mass ratio of aluminum chloride to spherical calcium carbonate is 1:0.08, and the concentration of aluminum chloride in the first reaction solution is 3M; add a 2.5M sodium carbonate solution to adjust the pH of the first reaction solution to 4.0 and then keep it at a constant temperature. The second reaction solution was obtained after aging for 2.2 hours.

[0050] Step (2): After cooling the second reaction solution to 35°C, filter it. Add polyhexamethylene biguanide solution to the obtained filtrate, and stir the mixture at a constant temperature of 45°C for 60 min to obtain the third reaction solution. The concentration of the polyhexamethylene biguanide solution is 0.5 wt%, and the amount of polyhexamethylene biguanide added is 5 wt% of the mass of the second reaction solution.

[0051] Step (3): Add mannitol to the third reaction solution and disperse it evenly to obtain a treatment solution, wherein the amount of mannitol added is 3.6% of the mass of the third reaction solution; add deionized water, stir thoroughly, and filter to obtain modified polyaluminum chloride with high phosphorus removal performance, wherein the mass fraction of alumina in the modified polyaluminum chloride is ≥10%.

[0052] Example 4

[0053] This embodiment provides a modified polyaluminum chloride with high phosphorus removal performance and its preparation method. The preparation method of the modified polyaluminum chloride with high phosphorus removal performance specifically includes the following steps:

[0054] Step (1): Add aluminum chloride, zirconium oxychloride, and spherical calcium carbonate to deionized water to obtain the first reaction solution, wherein the molar ratio of aluminum chloride to zirconium oxychloride is 1:0.05, the mass ratio of aluminum chloride to spherical calcium carbonate is 1:0.11, and the concentration of aluminum chloride in the first reaction solution is 2.3M; add sodium carbonate solution with a concentration of 2.9M to adjust the pH of the first reaction solution to 3.95, and then age it at a constant temperature of 67℃ for 2.7h to obtain the second reaction solution;

[0055] Step (2): After cooling the second reaction solution to 31°C, filter it. Add polyhexamethylene biguanide solution to the obtained filtrate, and stir the mixture at a constant temperature of 55°C for 65 min to obtain the third reaction solution. The concentration of the polyhexamethylene biguanide solution is 0.8 wt%, and the amount of polyhexamethylene biguanide added is 3.6 wt% of the mass of the second reaction solution.

[0056] Step (3): Add mannitol to the third reaction solution and disperse it evenly to obtain a treatment solution, wherein the amount of mannitol added is 3.3% of the mass of the third reaction solution; add deionized water, stir thoroughly, and filter to obtain modified polyaluminum chloride with high phosphorus removal performance, wherein the mass fraction of alumina in the modified polyaluminum chloride is ≥10%.

[0057] Comparative Example 1

[0058] This comparative example provides a modified polyaluminum chloride with high phosphorus removal performance. The difference from Example 1 is that zirconium oxychloride is not added in step (1), while other operating steps and process parameters are exactly the same as in Example 1.

[0059] Comparative Example 2

[0060] This comparative example provides a modified polyaluminum chloride with high phosphorus removal performance. The difference from Example 1 is that in step (2), polyhexamethylene biguanide solution is not added. Other operating steps and process parameters are exactly the same as in Example 1.

[0061] Comparative Example 3

[0062] This comparative example provides a modified polyaluminum chloride with high phosphorus removal performance. The difference from Example 1 is that in step (1), spherical calcium carbonate is not added, and sodium hydroxide solution of the same concentration is used. Other operating steps and process parameters are exactly the same as in Example 1.

[0063] The modified polyaluminum chloride with high phosphorus removal performance in Examples 1-4 and Comparative Examples 1-3 was subjected to performance testing, and the specific process is as follows:

[0064] Phosphorus removal efficiency test: Prepare a phosphate standard water sample of known concentration and add it to the sample. Perform rapid stirring, slow stirring, and static sedimentation sequentially. Take the supernatant and measure its total phosphorus concentration using spectrophotometry. Calculate the phosphorus removal efficiency: Phosphorus removal efficiency = (phosphate standard water sample phosphorus concentration - supernatant phosphorus concentration) / phosphate standard water sample phosphorus concentration × 100%;

[0065] Flocculation performance test: Prepare a standard water sample of kaolin (or humic acid) with known turbidity and add it to the sample. Perform rapid stirring, slow stirring, and static sedimentation sequentially. Take the supernatant and measure its turbidity using a turbidimeter. Calculate the turbidity removal rate: Turbidity removal rate = (turbidity of kaolin (or humic acid) standard water sample - turbidity of supernatant) / turbidity of kaolin (or humic acid) standard water sample × 100%;

[0066] The test results are shown in Table 1.

[0067] Table 1 Performance test results of Examples 1-4 and Comparative Examples 1-3

[0068]

[0069] The test results from Example 1 and Comparative Example 1 show that omitting the addition of zirconium oxychloride resulted in the failure to form the crucial Al-O-Zr hybrid core structure. The lack of high-affinity chemilinkage sites provided by zirconium atoms led to a decrease in phosphorus removal efficiency; simultaneously, the contribution of zirconium's high valence state to increasing the overall positive charge density of the polymer also disappeared, resulting in a weakened ability to neutralize negatively charged colloids and organic matter in water, thus reducing its flocculation performance.

[0070] The test results of Example 1 and Comparative Example 2 show that omitting the introduction of polyhexamethylene biguanide and relying solely on the chemical coordination of zirconium sites weakens the phosphorus capture ability, thus reducing the phosphorus removal efficiency. At the same time, the lack of the long-chain structure of polyhexamethylene biguanide can simultaneously adsorb multiple micro-flocs formed by charge neutralization, accelerating the sedimentation of the flocs, thereby leading to a decrease in flocculation performance.

[0071] The test results of Example 1 and Comparative Example 3 show that when spherical calcium carbonate is omitted and rapid alkalization is carried out using only sodium hydroxide solution, the local pH in the reaction system becomes too high due to the rapid addition of alkali, resulting in the formation of a large amount of low-activity amorphous aluminum hydroxide precipitate. Therefore, its phosphorus removal efficiency and flocculation performance both decrease.

[0072] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing modified polyaluminum chloride with high phosphorus removal performance, characterized in that, The preparation method includes: Step (1): Add aluminum chloride, zirconium oxychloride, and spherical calcium carbonate to deionized water to obtain the first reaction solution. Add sodium carbonate solution to adjust the pH of the first reaction solution and then age it at a constant temperature to obtain the second reaction solution. Step (2): After cooling the second reaction solution, filter it, add polyhexamethylene biguanide solution to the obtained filtrate and stir at a constant temperature to obtain the third reaction solution; Step (3): Add mannitol to the third reaction solution and disperse it evenly to obtain the treatment solution. Add deionized water, stir, and filter to obtain modified polyaluminum chloride with high phosphorus removal performance.

2. The method for preparing modified polyaluminum chloride with high phosphorus removal performance according to claim 1, characterized in that, In step (1): the molar ratio of aluminum chloride to zirconium oxychloride is 1:(0.04-0.06).

3. The method for preparing modified polyaluminum chloride with high phosphorus removal performance according to claim 1, characterized in that, In step (1): the mass ratio of aluminum chloride to spherical calcium carbonate is 1:(0.08-0.12).

4. The method for preparing modified polyaluminum chloride with high phosphorus removal performance according to claim 1, characterized in that, In step (1): the sodium carbonate solution is used to adjust the pH of the first reaction solution to 3.8-4.

0.

5. The method for preparing modified polyaluminum chloride with high phosphorus removal performance according to claim 1, characterized in that, In step (2): the amount of polyhexamethylene biguanide added is 3-5 wt% of the mass of the second reaction solution.

6. The method for preparing modified polyaluminum chloride with high phosphorus removal performance according to claim 1, characterized in that, In step (3): the amount of mannitol added is 3-4% of the mass of the third reaction solution.

7. The method for preparing modified polyaluminum chloride with high phosphorus removal performance according to claim 1, characterized in that, In step (3): the mass fraction of alumina in the modified polyaluminum chloride is ≥10%.

8. A modified polyaluminum chloride with high phosphorus removal performance, characterized in that, The modified polyaluminum chloride with high phosphorus removal performance is prepared according to any one of claims 1-7.

9. The application of a modified polyaluminum chloride with high phosphorus removal performance prepared by a method according to any one of claims 1-7 in wastewater treatment.

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