A phosphorus adsorbent composition and use thereof

Abstract

This invention discloses a phosphorus adsorbent composition and its application, belonging to the field of water treatment technology. When the phosphorus adsorbent composition is applied to adsorb and remove phosphorus in phosphorus-containing water, the phosphorus in the water is in the form of phosphorus-containing anions. The phosphorus adsorbent composition comprises a physically mixed phosphorus adsorbent and natural minerals; the zero charge point value of the natural minerals is lower than the pH value of the water; and the specific surface area of ​​the natural minerals is greater than or equal to 5 m². 2 / g; the volume ratio of the natural ore to the phosphorus adsorbent is (0.1~20):1. This invention accelerates the mass transfer process of phosphorus-containing anions such as phosphate ions during phosphorus adsorption through the physical mechanism of electrostatic repulsion, thereby improving the adsorption rate and capacity of the phosphorus adsorbent and enhancing its adsorption performance. Furthermore, the application method of this phosphorus adsorbent composition is simple, low-cost, requires no external energy consumption, and is environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and more specifically, relates to a phosphorus adsorbent composition and its application. Background Technology

[0002] With continuous urbanization and industrialization, and the extensive use of agricultural fertilizers and phosphorus-containing detergents, the amount of phosphorus nutrients entering lakes, reservoirs, and rivers is constantly increasing, leading to massive algal blooms and widespread eutrophication. Eutrophication not only severely damages the aquatic ecosystem, reduces the usability of water bodies, and accelerates their decline, but also affects navigation and hinders economic development. Currently, the eutrophication problem in my country's rivers and lakes is becoming increasingly serious, making the treatment of phosphorus-containing wastewater a crucial issue that urgently needs to be addressed.

[0003] Phosphorus adsorbents (such as metal oxides and modified biochar) are key materials for treating phosphorus pollution in water bodies.

[0004] The main approaches to improving the performance of phosphorus adsorbents currently include: One approach is to increase the specific surface area by constructing complex microstructures or reducing the particle size of materials, or to load substances with a strong affinity for phosphates to increase adsorption sites. Another approach is to apply an external electric / magnetic field to make the phosphorus adsorbent positively charged, thereby enhancing the electrostatic adsorption of phosphate ions.

[0005] However, the performance improvement effect of the above methods is limited, and they generally suffer from problems such as complex operation, high energy consumption, poor economic efficiency, or easy to cause secondary pollution.

[0006] Therefore, developing a method that can significantly improve the performance of phosphorus adsorbents is an urgent technical problem that needs to be solved in this field. Summary of the Invention

[0007] 1. The problem to be solved To address the technical problem that the adsorption performance of phosphorus adsorbents in the prior art needs to be improved, this invention provides a phosphorus adsorbent composition that accelerates the mass transfer process of phosphorus-containing anions such as phosphate ions during adsorption through the physical mechanism of electrostatic repulsion, thereby improving the adsorption rate and adsorption capacity of the phosphorus adsorbent and enhancing its adsorption performance. Furthermore, the preparation and application methods of this phosphorus adsorbent composition are simple, low-cost, require no external energy consumption, and are environmentally friendly.

[0008] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a phosphorus adsorbent composition comprising a physically mixed phosphorus adsorbent and a natural ore; the natural ore has a zero charge point of 1 to 6 and a specific surface area greater than or equal to 5 m². 2 / g; the volume ratio of natural ore to phosphorus adsorbent is (0.1~20):1.

[0009] Phosphorus in water mainly exists in inorganic form, specifically as phosphorus-containing anions such as orthophosphate, polyphosphate, pyrophosphate, and metaphosphate. The pH range of phosphorus-containing water is mostly 6.5–8.5. This invention physically mixes a phosphorus adsorbent with a natural mineral with a low zero-charge point (e.g., a zero-charge point of 1–6) to obtain a phosphorus adsorbent composition. When treating the aforementioned phosphorus-containing water, the natural mineral, due to its negative charge (lower than the pH of the water), generates electrostatic repulsion with the negatively charged phosphorus-containing anions, thereby promoting the migration of more phosphorus-containing anions to the phosphorus adsorbent and accelerating this migration process, effectively improving the adsorption rate and adsorption capacity of the phosphorus adsorbent.

[0010] In addition, the natural ore in the phosphorus adsorbent composition of the present invention must have a sufficient specific surface area, for example, greater than or equal to 5 m². 2 The specific surface area is set at / g to ensure that the natural ore has sufficient negative charge density per unit mass, which can generate a strong electrostatic repulsion force on phosphorus-containing anions, promoting and accelerating the migration of phosphorus-containing anions to the phosphorus adsorbent.

[0011] Furthermore, the zero charge point of the natural ore is 2 to 6, and more preferably 3 to 5, for example 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5.

[0012] Furthermore, the specific surface area of ​​the natural ore is greater than or equal to 10 m². 2 / g, more preferably 20 m 2 / g~110m 2 / g, the optimal value is 25 m 2 / g~110 m 2 / g, for example 25 m 2 / g、30 m 2 / g、35 m 2 / g、40 m 2 / g、45 m 2 / g、50 m 2 / g、55 m 2 / g、60 m 2 / g、65 m 2 / g、70 m 2 / g、75 m 2 / g、80 m 2 / g、85 m2 / g、90 m 2 / g、95 m 2 / g, 100m 2 / g, 105 m 2 / g、110 m 2 / g.

[0013] Further, the volume ratio of natural ore to phosphorus adsorbent is (0.3~20):1, more preferably (0.3~2):1, for example, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, and most preferably (0.5~1):1.

[0014] As a preferred embodiment of any of the first aspects of the present invention, the zero charge point of the natural ore is smaller than that of the phosphorus adsorbent; the particle size ratio of the natural ore to the phosphorus adsorbent is 1:(1~1000).

[0015] In this invention, the zero charge point of the natural ore is smaller than that of the phosphorus adsorbent, which is beneficial for constructing an adsorption system in which the zero charge point value of the natural ore is less than the pH value of the water body and less than the zero charge point value of the phosphorus adsorbent. In this system, the natural ore is negatively charged and the phosphorus adsorbent is positively charged. The natural ore promotes the migration of phosphorus-containing anions to the phosphorus adsorbent, and the phosphorus adsorbent pulls the phosphorus-containing anions to migrate to the phosphorus adsorbent. The two work together to further improve the adsorption rate and adsorption capacity of the phosphorus adsorbent.

[0016] Furthermore, the difference between the zero charge point of the phosphorus adsorbent and the natural ore is greater than 2, and more preferably 2 to 8, for example 2, 3, 4, 5, 6, 7, 8.

[0017] Furthermore, the particle size of the phosphorus adsorbent is 0.2 μm to 6 mm, and more preferably 20 μm to 5 mm.

[0018] As a preferred embodiment of any of the first aspects of the present invention, the natural ore is selected from one or more of zeolite, montmorillonite, sepiolite, bentonite, quartz, diatomite and talc; the phosphorus adsorbent is selected from one or more of activated carbon, lanthanum-modified activated carbon, lanthanum-modified zeolite and magnesium-modified biochar.

[0019] As a preferred embodiment of any of the first aspects of the present invention, the phosphorus adsorbent has a phosphorus adsorption capacity greater than or equal to 2 mg / g.

[0020] The phosphorus adsorbent in this invention needs to have a certain adsorption capacity. When the adsorption capacity of the phosphorus adsorbent is too small, for example, less than 2 mg / g, the phosphorus adsorbent will quickly reach saturation when applied, and the natural ore in this invention cannot significantly improve the adsorption rate and adsorption capacity of the phosphorus adsorbent.

[0021] A second aspect of the present invention provides the application of a phosphorus adsorbent composition for adsorbing and removing phosphorus in phosphorus-containing water bodies, wherein the phosphorus in the water body in which the application is performed is in the form of phosphorus-containing anions; The phosphorus adsorbent composition comprises a physically mixed phosphorus adsorbent and natural minerals; The zero charge point value of the natural ore is less than the pH value of the water body; The specific surface area of ​​the natural ore is greater than or equal to 5 m². 2 / g; The volume ratio of the natural ore to the phosphorus adsorbent is (0.1~20):1.

[0022] In this invention, the natural ore carries a negative charge due to its zero-charge point being lower than the pH of the water. This negative charge generates electrostatic repulsion with the negatively charged phosphorus-containing anions, thereby promoting the migration of more phosphorus-containing anions to the phosphorus adsorbent and accelerating this migration process, effectively improving the adsorption rate and capacity of the phosphorus adsorbent. Simultaneously, sufficient specific surface area and a suitable volume ratio facilitate the natural ore to generate a strong electrostatic repulsion force on phosphorus-containing anions per unit mass, promoting and accelerating the migration of phosphorus-containing anions to the phosphorus adsorbent, further improving the adsorption rate and capacity of the phosphorus adsorbent.

[0023] Furthermore, the zero charge point of the natural ore is 1 to 6, more preferably 2 to 6, and even more preferably 3 to 5, for example 3, 3.2, 3.4, 3.6, 3.8, 4, 4.2, 4.4, 4.6, 4.8, 5.

[0024] Furthermore, the specific surface area of ​​the natural ore is greater than or equal to 10 m². 2 / g, more preferably 20 m 2 / g~110m 2 / g, the optimal value is 25 m 2 / g~110 m 2 / g, for example 25 m 2 / g、30 m 2 / g、35 m 2 / g、40 m 2 / g、45 m 2 / g、50 m 2 / g、55 m 2 / g、60 m 2 / g、65 m 2 / g、70 m 2 / g、75 m 2 / g、80 m 2 / g、85 m 2 / g、90 m 2 / g、95 m 2 / g, 100m 2 / g, 105 m 2 / g、110 m 2 / g.

[0025] Further, the volume ratio of natural ore to phosphorus adsorbent is (0.3~20):1, more preferably (0.3~2):1, for example, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, and most preferably (0.5~1):1.

[0026] As a preferred embodiment of any of the second aspects of the present invention, the difference between the pH value of the water body and the zero charge point value of the natural mineral is greater than or equal to 0.5, and more preferably 1 to 4, for example 1, 1.5, 2, 2.5, 3, 3.5, 4.

[0027] In this invention, when the pH value of the water body and the zero charge point value of the natural mineral reach a certain difference, such as greater than or equal to 0.5, it is beneficial for the natural mineral to generate a strong electrostatic repulsion force on the phosphorus-containing anions in the water.

[0028] As a preferred embodiment of any of the second aspects of the present invention, the pH value of the water body is less than the zero charge point value of the phosphorus adsorbent.

[0029] In this invention, when the pH value of the water is less than the zero charge point value of the phosphorus adsorbent, the phosphorus adsorbent is positively charged, which can attract and accelerate the migration of phosphorus-containing anions to the phosphorus adsorbent, thereby further improving the adsorption rate and adsorption capacity of the phosphorus adsorbent.

[0030] Furthermore, the difference between the zero charge point of the phosphorus adsorbent and the natural ore is greater than 2, and more preferably 2 to 8, for example 2, 3, 4, 5, 6, 7, 8.

[0031] The appropriate zero-charge point difference between the phosphorus adsorbent and the natural ore helps to broaden the application range of the phosphorus adsorbent composition. While maximizing the adsorption rate and adsorption capacity of the phosphorus adsorbent, it avoids the limitation of the application of the invention by the strict pH adjustment range of the water body.

[0032] As a preferred embodiment of any of the second aspects of the present invention, the pH of the water body is 5 to 10.

[0033] Furthermore, the zero charge point of natural minerals is 1 to 5, excluding 5; the pH of water is 5 to 8; and the zero charge point of phosphorus adsorbents is 8 to 14, excluding 8.

[0034] As a preferred embodiment of any of the second aspects of the present invention, the particle size ratio of natural ore to phosphorus adsorbent is 1:(1~1000).

[0035] Furthermore, the particle size of the phosphorus adsorbent is 0.2 μm to 6 mm, and more preferably 20 μm to 5 mm.

[0036] As a preferred embodiment of any of the second aspects of the present invention, the phosphorus-containing anions include one or more of orthophosphate ions, polyphosphate ions, pyrophosphate ions, metaphosphate ions, and polymeric organophosphate ions; the natural ore is selected from one or more of zeolite, montmorillonite, sepiolite, bentonite, quartz, diatomite, and talc; and the phosphorus adsorbent is selected from one or more of activated carbon, lanthanum-modified activated carbon, lanthanum-modified zeolite, and magnesium-modified biochar.

[0037] As a preferred embodiment of any of the second aspects of the present invention, the total molar concentration of interfering anions in the water body is less than or equal to three times the molar concentration of phosphorus, and the interfering anions include one or more of chloride ions, sulfate ions and nitrate ions.

[0038] As a preferred embodiment of any of the second aspects of the present invention, the total phosphorus concentration in the water body is 1 mg / L to 500 mg / L.

[0039] Furthermore, the total phosphorus concentration in the water body ranges from 20 mg / L to 500 mg / L.

[0040] As a preferred embodiment of any of the second aspects of the present invention, the phosphorus adsorbent has a phosphorus adsorption capacity greater than or equal to 2 mg / g.

[0041] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The application of the phosphorus adsorbent composition provided by the present invention in the adsorption and removal of phosphorus in phosphorus-containing water bodies involves physically mixing natural minerals with zero charge points lower than the pH of the water body with the phosphorus adsorbent. Through the physical mechanism of electrostatic repulsion between the negatively charged natural minerals and phosphorus-containing anions such as phosphate ions, the migration of phosphorus-containing anions to the phosphorus adsorbent is promoted and accelerated, which effectively improves the adsorption rate and adsorption capacity of the phosphorus adsorbent, especially the adsorption rate, which is increased by at least 95% and up to 170%. The preparation of the phosphorus adsorbent composition is simple, requiring only the physical mixing of natural minerals existing in nature with the phosphorus adsorbent. The acquisition cost of natural minerals is low, which can reduce the overall application cost of the phosphorus adsorbent composition and has good economic efficiency. Moreover, no external energy is required during application, avoiding the increase in phosphorus removal costs. Natural minerals will not cause secondary pollution and are environmentally friendly.

[0042] (2) The application of the phosphorus adsorbent composition provided by the present invention in the adsorption and removal of phosphorus in phosphorus-containing water bodies further improves the adsorption rate and adsorption capacity of the phosphorus adsorbent by controlling the pH value of the water body to be less than the zero charge point value of the phosphorus adsorbent. This is achieved by controlling the pH value of the water body to be less than the zero charge point value of the phosphorus adsorbent, so that the phosphorus adsorbent is positively charged in the water body. The phosphorus adsorbent is then attracted and accelerated to the phosphorus-containing anions such as phosphate ions by the physical mechanism of electrostatic attraction, thereby further improving the adsorption rate and adsorption capacity of the phosphorus adsorbent.

[0043] (3) When the phosphorus adsorbent composition provided by the present invention is used to adsorb and remove phosphorus in phosphorus-containing water, when the pH value of the water and the zero charge point value of the natural mineral reach a certain difference, for example, greater than or equal to 0.5, it is beneficial for the natural mineral to generate a strong electrostatic repulsion force on the phosphorus-containing anions in the water.

[0044] (4) The application of the phosphorus adsorbent composition provided by the present invention in the adsorption and removal of phosphorus in phosphorus-containing water bodies is simple in process and reasonable in design, which is conducive to its promotion and application in the field of water treatment.

[0045] (5) The phosphorus adsorbent composition provided by the present invention includes a physically mixed phosphorus adsorbent and natural minerals. Since the pH range of the phosphorus-containing water body used is mostly 6.5~8.5, the zero charge point of the natural mineral is selected to be 1~6, so that when applied to the phosphorus-containing water body, the zero charge point of the natural mineral is lower than the pH of the water body and carries a negative charge. It generates electrostatic repulsion with the phosphorus-containing anions that also carry a negative charge, thereby promoting more phosphorus-containing anions to migrate to the phosphorus adsorbent and accelerating this migration process, effectively improving the adsorption rate and adsorption capacity of the phosphorus adsorbent.

[0046] (6) The phosphorus adsorbent composition provided by the present invention can be obtained by simply physically mixing natural minerals that exist in nature with phosphorus adsorbents in the prior art, which can reduce the application cost of phosphorus adsorption and removal in phosphorus-containing water bodies; moreover, natural minerals are less likely to cause secondary pollution and are environmentally friendly; and can effectively improve the adsorption rate and adsorption capacity of phosphorus adsorbents. Attached Figure Description

[0047] Figure 1 This is a bar chart showing the phosphorus adsorption amount of different volume ratio phosphorus adsorbent compositions in Test Example 1 of the present invention after 1 h of adsorption. Figure 2 This is a bar chart showing the phosphorus adsorption amount of different particle size phosphorus adsorbent compositions after 1 h of adsorption in Test Example 2 of the present invention; Figure 3 This is a bar chart showing the phosphorus adsorption amount of the phosphorus adsorbent composition after 1 h of adsorption under different interfering ion concentrations in Test Example 3 of the present invention. Figure 4 This is a bar chart comparing the phosphorus adsorption amount of different pH phosphorus adsorbent compositions and phosphorus adsorption after 1 h of phosphorus adsorption in Test Examples 4 and 5 of the present invention. Figure 5 This is a bar chart comparing the phosphorus adsorption capacity of the phosphorus adsorbent composition, phosphorus adsorbent, and zeolite at different pH levels for 1 h in Test Examples 6, 7, and 8 of the present invention. Detailed Implementation

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0049] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0050] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a numerical range of 1 to 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as "less than 4.5," which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0051] It should be noted that the method for determining the point of zero charge (PZC) is as follows: the analyte is added to a 0.01 mol / L NaCl solution at a solid-liquid mass ratio of 1:100, and after shaking and equilibration at 25°C for 30 minutes, the PZC is determined by potentiometric titration. The PZC values ​​were: clinoptilolite (CP) 4.5, chabazite 6.7, lanthanum-modified activated carbon (La-AC) 8.2 in Examples 1-3, and quartz (SiO2) with average particle sizes of 0.2 μm, 20 μm, and 200 μm, respectively, with PZC values ​​of 2.4, 2.3, and 2.5 (it should be noted that this error is a measurement error).

[0052] It should be noted that, according to the BET specific surface area measurement method, the specific surface areas of quartz (SiO2) with average particle sizes of 0.2 μm, 20 μm, and 200 μm are 26.7 m², respectively. 2 / g, 0.45 m 2 / g, 0.03 m 2 / g. The specific surface area of ​​clinoptilolite and chabazite is at least 10 m².2 / g.

[0053] It should be noted that the circulating flow mode in the test example refers to the effluent after being treated by the adsorption filter column being discharged back into the inlet pool of the adsorption filter column, that is, the effluent and inlet of the adsorption filter column are in the same container; the adsorption rate is reflected by the amount of phosphorus adsorbed per unit time (1 h).

[0054] The present invention will be further described below with reference to specific embodiments.

[0055] Materials used in preparation: Clinoptilolite, chalcogenite, quartz with average particle sizes of 0.2 μm, 20 μm, and 200 μm, granular activated carbon, and lanthanum nitrate are all commercially available.

[0056] Example 1 This embodiment provides a phosphorus adsorbent composition consisting of natural ore and phosphorus adsorbent.

[0057] The natural ore is clinoptilolite (denoted as CP), and the phosphorus adsorbent is lanthanum-modified activated carbon (denoted as La-AC). The preparation method of La-AC includes the following specific steps: 1. Wash and pre-treat activated carbon particles that have been sieved to 1 mm are mixed with a 0.1 M lanthanum nitrate solution at a solid-liquid mass ratio of 1:5 and impregnated for 12 h to allow lanthanum ions to be fully adsorbed on the surface and in the pores of the activated carbon.

[0058] 2. The solid-liquid mixture obtained in step 1 is dried under vacuum at 80°C to constant weight to obtain a solid mixture.

[0059] 3. The solid mixture was placed in a muffle furnace and heated to 500°C at a rate of 5°C / min. After calcination for 2 hours, lanthanum nitrate decomposed and was immobilized on activated carbon in the form of oxides. After cooling, lanthanum-modified activated carbon (La-AC) with an average particle size of 1 mm was obtained.

[0060] Clinoptilolite (CP) with an average particle size of 1 mm was uniformly mixed with lanthanum-modified activated carbon (La-AC) at volume ratios of 0.1:1, 0.3:1, 0.5:1, 1:1, 2:1, 10:1, and 20:1 to obtain corresponding phosphorus adsorbent compositions, which were denoted as 0.1CP / La-AC, 0.3CP / La-AC, 0.5CP / La-AC, CP / La-AC, 2CP / La-AC, 10CP / La-AC, and 20CP / La-AC, respectively.

[0061] Test Example 1 This test example is used to test the adsorption rate of each phosphorus adsorbent composition in Example 1, and specifically includes the following steps: 1. Equal volumes of CP, La-AC, 0.1CP / La-AC, 0.3CP / La-AC, 0.5CP / La-AC, CP / La-AC, 2CP / La-AC, 10CP / La-AC, and 20CP / La-AC from Example 1 were respectively packed into an adsorption filter column with an inner diameter of 1 cm and a height of 20 cm.

[0062] 2. The water flow direction of the adsorption filter column is bottom inlet and top outlet, and it is driven by a peristaltic pump with a flow rate of 2 mL / s.

[0063] 3. Treat 10 L of water with a phosphorus (P) concentration of 50 mg / L using a circulating flow method. The specific form of phosphorus in this water is phosphate (PO4). 3- The pH of the water was adjusted to 6.9 with sodium hydroxide before treatment.

[0064] 4. After 1 hour of water treatment in step 3 using the adsorption filtration column, take a 5 mL sample and test the phosphate concentration, and calculate the amount of phosphorus adsorbed.

[0065] The adsorption rates of each phosphorus adsorbent composition in Example 1 are as follows: Figure 1 As shown.

[0066] Depend on Figure 1 It can be seen that when the volume ratio of CP to La-AC is greater than 0.1:1, the adsorption capacity of La-AC for phosphorus per unit time is significantly increased, that is, the adsorption rate of La-AC is significantly increased. The reason is that when the pH of the water is 6.9, the PZC (4.5) of CP is lower than the pH of the water, so the surface of CP is negatively charged, which generates electrostatic repulsion against phosphate ions, promotes the accelerated migration of phosphate ions to La-AC, and thus increases the adsorption rate of phosphate ions by La-AC.

[0067] Example 2 This embodiment provides a phosphorus adsorbent composition consisting of natural ore and phosphorus adsorbent.

[0068] The natural ore used is quartz (SiO2), and the phosphorus adsorbent is lanthanum-modified activated carbon (La-AC). The preparation method of lanthanum-modified activated carbon (La-AC) includes the following specific steps: 1. Wash and pre-treat activated carbon particles that have been sieved to 200 μm are mixed with a 0.1 M lanthanum nitrate solution at a solid-liquid mass ratio of 1:5 and impregnated for 12 h to allow lanthanum ions to be fully adsorbed on the surface and in the pores of the activated carbon.

[0069] 2. The solid-liquid mixture obtained in step 1 is dried under vacuum at 80°C to constant weight to obtain a solid mixture.

[0070] 3. The solid mixture was placed in a muffle furnace and heated to 500°C at a rate of 5°C / min. After calcination for 2 hours, lanthanum nitrate was decomposed and immobilized on activated carbon in the form of oxides. After cooling, lanthanum-modified activated carbon (La-AC) with an average particle size of 200 μm was obtained.

[0071] Quartz (SiO2) with average particle sizes of 0.2 μm, 20 μm, and 200 μm was ultrasonically cleaned with deionized water and then mixed with lanthanum-modified activated carbon (La-AC) with an average particle size of 200 μm at a volume ratio of 1:1 to obtain corresponding phosphorus adsorbent compositions, which were denoted as 0.2 μmSiO2 / La-AC, 20 μmSiO2 / La-AC, and 200 μmSiO2 / La-AC, respectively.

[0072] Test Example 2 This test example is used to test the adsorption rate of each phosphorus adsorbent composition in Example 2, and specifically includes the following steps: 1. Equal volumes of La-AC, 0.2μmSiO2 / La-AC, 20μmSiO2 / La-AC, and 200μmSiO2 / La-AC from Example 2 were respectively packed into an adsorption filter column with an inner diameter of 1 cm and a height of 20 cm, and 0.1 μm microporous filter membranes were placed at the top and bottom of the column to prevent the loss of phosphorus adsorbent material.

[0073] 2. The water flow direction of the adsorption filter column is bottom inlet and top outlet, and it is driven by a peristaltic pump with a flow rate of 2 mL / s.

[0074] 3. Treat 10 L of water with a phosphorus concentration of 50 mg / L using a circulating flow method. The specific form of phosphorus in this water is phosphate (PO4). 3- The pH of the water was adjusted to 6.9 with sodium hydroxide before treatment.

[0075] 4. After 1 hour of water treatment in step 3 using the adsorption filtration column, take a 5 mL sample and test the phosphate concentration, and calculate the amount of phosphorus adsorbed.

[0076] The adsorption rates of each phosphorus adsorbent composition in Example 2 are as follows: Figure 2 As shown.

[0077] Depend on Figure 2 It can be seen that when SiO2 with an average particle size of 0.2 μm is mixed with La-AC, the adsorption capacity of La-AC for phosphorus per unit time is significantly increased, that is, the adsorption rate of La-AC is significantly increased. However, the improvement effect is not obvious when SiO2 with an average particle size of 20 μm and 200 μm is mixed with La-AC. This is because, although the PZC of SiO2 (2.3~2.5) is much lower than the pH of water (6.9), the specific surface area of ​​large-particle-size SiO2 is small, for example, 0.45 m².2 / g or 0.03 m 2 With a particle size of / g, the negative charge density per unit mass is extremely low, resulting in weak electrostatic repulsion towards phosphate ions, insufficient to accelerate their migration towards La-AC. In contrast, small-particle-size SiO2 has a large specific surface area, for example, 26.7 m². 2 The negative charge density per unit mass is extremely high, resulting in a strong electrostatic repulsion of phosphate ions. This, in turn, accelerates the migration of phosphate ions to La-AC, thereby increasing the adsorption rate of phosphate ions by La-AC.

[0078] Test Example 3 This test example is used to test the effect of different interfering ion concentrations on the adsorption rate of CP / La-AC in Example 1, and specifically includes the following steps: 1. The CP / La-AC from Example 1 was packed into an adsorption filter column with an inner diameter of 1 cm and a height of 20 cm.

[0079] 2. The water flow direction of the adsorption filter column is bottom inlet and top outlet, and it is driven by a peristaltic pump with a flow rate of 2 mL / s.

[0080] 3. Treat 10 L of water with a phosphorus (P) concentration of 50 mg / L (i.e., 1.61 mM) using a circulating flow method. The specific form of phosphorus in this water is phosphate (PO4). 3- The pH of the water was adjusted to 6.9 with sodium hydroxide before treatment.

[0081] 4. After 1 hour of water treatment in step 3 using the adsorption filtration column, take a 5 mL sample and test the phosphate concentration, and calculate the amount of phosphorus adsorbed.

[0082] 5. Following the conditions in steps 1 to 4, replace the water containing 1.61 mM phosphorus in step 3 with water containing 1.61 mM sodium sulfate + 1.61 mM phosphorus, 3.22 mM sodium sulfate + 1.61 mM phosphorus, 4.83 mM sodium sulfate + 1.61 mM phosphorus, 6.44 mM sodium sulfate + 1.61 mM phosphorus, 8.05 mM sodium sulfate + 1.61 mM phosphorus, and 9.66 mM sodium sulfate + 1.61 mM phosphorus, respectively. Measure the adsorption rate of CP / La-AC when sodium sulfate is used as an interfering anion, i.e., the amount of phosphorus adsorbed by CP / La-AC per unit time when the molar concentration ratio of interfering anion to phosphorus is 1, 2, 3, 4, and 5, respectively.

[0083] The adsorption rates of CP / La-AC in Example 1 under different interfering ion concentrations in Test Example 3 are as follows: Figure 3 As shown.

[0084] Depend on Figure 3It is evident that interfering anions (sulfate ions) significantly impact the performance of phosphorus adsorbents. Specifically, when sulfate ions are absent in the water (i.e., the molar concentration ratio is 0), the adsorption capacity of the phosphorus adsorbent reaches its maximum value of 20.10 mg-P / g per unit time, meaning that 1g of adsorbent can adsorb 20.10mg of phosphorus (P). As the sulfate-to-phosphorus concentration ratio increases, the phosphorus adsorption capacity per unit time exhibits a clear non-linear decreasing trend: when the ratio rises to 1, the adsorption capacity decreases to 17.65 mg-P / g; when the ratio increases to 3, the adsorption capacity drops sharply to 11.80 mg-P / g; and when the ratio further increases to 6, the adsorption capacity is only 6.40 mg-P / g. This trend reveals the dominant role of the anion competitive adsorption mechanism, namely, sulfate ions occupy the active sites on the adsorbent surface, thereby inhibiting the phosphorus adsorption effect. It is noteworthy that the decrease in adsorption capacity is most dramatic in the low ratio range (0-3), while the decreasing trend gradually slows down after the ratio exceeds 3, indicating that the adsorbent may be approaching adsorption saturation at high interfering ion concentrations. This result clarifies that in practical applications, the concentration of interfering anions needs to be controlled below a certain threshold, such as a molar ratio of interfering anions to phosphorus ≤ 3, in order to maintain the adsorbent's high-efficiency phosphorus removal performance.

[0085] Test Example 4 This test example is used to test the effect of different pH values ​​on the adsorption rate of CP / La-AC in Example 1, and specifically includes the following steps: 1. The CP / La-AC from Example 1 was packed into an adsorption filter column with an inner diameter of 1 cm and a height of 20 cm.

[0086] 2. The water flow direction of the adsorption filter column is bottom inlet and top outlet, and it is driven by a peristaltic pump with a flow rate of 2 mL / s.

[0087] 3. Treat 10 L of water with a phosphorus (P) concentration of 50 mg / L using a circulating flow method. The specific form of phosphorus in this water is phosphate (PO4). 3- The pH of the water was adjusted to 7 with sodium hydroxide before treatment.

[0088] 4. After 1 hour of water treatment in step 3 using the adsorption filtration column, take a 5 mL sample and test the phosphate concentration, and calculate the amount of phosphorus adsorbed.

[0089] 5. Following the conditions in steps 1-4, replace the water in step 3 with water (phosphorus concentration of 50 mg / L) whose pH was adjusted to 3, 4, 5, 6, 8, 9, 10, and 11 with hydrochloric acid or sodium hydroxide, respectively, and measure the adsorption rate of CP / La-AC. Specific results are shown below. Figure 4 As shown.

[0090] Test Example 5 This test case is basically the same as Test Case 4, except that La-AC from Example 1 is used instead of CP / La-AC from Example 1, and the volume of La-AC is the same in both Test Cases 4 and 5. Specific results are as follows: Figure 4 As shown.

[0091] Depend on Figure 4 It can be seen that when the pH of the water is higher than the zero charge point of the natural ore, the adsorption rate of the phosphorus adsorbent composition is significantly higher than when the pH of the water is lower than the zero charge point of the natural ore.

[0092] When CP is positively charged, it inhibits the adsorption rate of phosphorus by La-AC, while when CP is negatively charged, it promotes the adsorption rate of phosphorus by La-AC regardless of whether La-AC is positively or negatively charged.

[0093] The adsorption rate of the phosphorus adsorbent composition is highest when the pH of the water is higher than the zero charge point of the natural ore but lower than the zero charge point of the phosphorus adsorbent.

[0094] Specifically, when the pH of the water is 3-4, CP carries a positive charge because the pH of the water is lower than its own PZC (4.5), while La-AC (PZC=8.2) also carries a positive charge at this time. The two compete for negatively charged phosphate ions in the water, resulting in the phosphorus adsorption capacity of the CP / La-AC system per unit time being significantly lower than that of La-AC alone, clearly demonstrating the inhibitory effect of the positive charge of CP.

[0095] When the water pH is ≥5, CP (Polyphosphate Concentrate) becomes a stable negatively charged state. When the water pH is 5-8, La-AC (PZC=8.2) remains positively charged. The electrostatic repulsion of CP drives phosphate ions to migrate towards La-AC. At the same time, the electrostatic attraction of La-AC pulls phosphate ions to migrate towards La-AC. The phosphorus adsorption capacity of the CP / La-AC system per unit time is 110.0%-152.8% higher than that of La-AC alone. The phosphorus adsorption capacity is highest at water pH 7, with a relatively large increase. When the water pH is 9-11, La-AC becomes negatively charged because the water pH is higher than its own PZC (8.2), generating electrostatic repulsion with phosphate ions. This causes a sharp drop in the phosphorus adsorption capacity of La-AC alone per unit time. For example, at water pH 11, the phosphorus adsorption capacity is only 2.5%. Despite having a phosphorus adsorption capacity of mg-P / g, CP still overcomes the negative charge barrier through continuous and stronger electrostatic repulsion, increasing the phosphorus adsorption capacity of the CP / La-AC system by 96.2%~172.0% per unit time compared to La-AC alone, although the phosphorus adsorption capacity per unit time is relatively low. Therefore, even though La-AC is negatively charged, the promoting effect of CP is still significant, meaning that the phosphorus adsorption promoting effect of negatively charged CP is not affected by the charge state of La-AC.

[0096] In summary, in the phosphorus adsorbent composition consisting of natural ore and phosphorus adsorbent, making the zero charge point of the natural ore less than the pH of the water body can significantly increase the phosphorus adsorption capacity of the phosphorus adsorbent; furthermore, making the zero charge point of the natural ore less than the pH of the water body less than the zero charge point of the phosphorus adsorbent can further increase the phosphorus adsorption capacity per unit time.

[0097] Example 3 This embodiment provides a phosphorus adsorbent composition composed of natural ore and phosphorus adsorbent, which is basically the same as that in Example 1, except that the natural ore is chabazite, and the volume ratio of chabazite to lanthanum modified activated carbon (La-AC) is 1:1. The resulting phosphorus adsorbent composition is denoted as chabazite / La-AC.

[0098] Test Example 6 This test case is basically the same as Test Case 4, except that the zeolite / La-AC in Example 3 is used instead of CP / La-AC in Example 1, and the pH values ​​tested are 4.5, 5.5, 6.5, 7.5, and 8.5, respectively.

[0099] Test Example 7 This test case is basically the same as Test Case 6, except that La-AC in Example 3 is used instead of chalcogenide / La-AC in Example 3.

[0100] Test Example 8 This test case is basically the same as Test Case 6, except that the chabazite in Example 3 is used instead of the chabazite / La-AC in Example 3.

[0101] The test results for test examples 6-8 are as follows: Figure 5 As shown.

[0102] from Figure 5 As can be seen, although the chabazite in the phosphorus adsorbent composition of Example 3 is different from the clinoptilolite in Example 1, and the PZC also differs significantly, the adsorption behavior of the phosphorus adsorbent composition of Example 3 is basically the same as that of Test Examples 4 and 5. For example, when the pH of the water is less than the zero charge point of chabazite (PZC is 6.7), such as pH 4.5, 5.5, and 6.5, chabazite exhibits a significant phosphorus adsorption inhibition effect due to its positive charge, significantly reducing the amount of phosphorus adsorbed by the phosphorus adsorbent; when the pH of the water is greater than the zero charge point of chabazite (PZC is 6.7), such as pH 7.5 and 8.5, chabazite exhibits a significant phosphorus adsorption promotion effect due to its negative charge, significantly increasing the amount of phosphorus adsorbed by the phosphorus adsorbent; and when the pH of the water is greater than the zero charge point of La-AC (PZC is 8.2), such as pH 8.5, La-AC exhibits a phosphorus adsorption inhibition effect due to its negative charge.

[0103] The above description provides an illustrative overview of the present invention and its embodiments. This description is not restrictive, and the embodiments shown are merely one example of the invention's implementation. Actual implementations are not limited to these examples. Therefore, if those skilled in the art are inspired by this description and design similar implementations and examples without departing from the spirit of the invention, such designs should fall within the scope of protection of the present invention.

Claims

1. The application of a phosphorus adsorbent composition in the adsorption and removal of phosphorus in phosphorus-containing water bodies, characterized in that, The phosphorus in the water is in the form of phosphorus-containing anions; The phosphorus adsorbent composition comprises a physically mixed phosphorus adsorbent and natural minerals; The zero charge point value of the natural ore is less than the pH value of the water body; The specific surface area of ​​the natural ore is greater than or equal to 5 m². 2 / g; The volume ratio of the natural ore to the phosphorus adsorbent is (0.1~20):

1.

2. The application of the phosphorus adsorbent composition according to claim 1 in the adsorption and removal of phosphorus in phosphorus-containing water bodies, characterized in that, The difference between the pH value of the water body and the zero charge point value of the natural ore is greater than or equal to 0.

5.

3. The application of the phosphorus adsorbent composition according to claim 1 in the adsorption and removal of phosphorus in phosphorus-containing water bodies, characterized in that, The pH value of the water body is less than the zero charge point value of the phosphorus adsorbent.

4. The application of the phosphorus adsorbent composition according to claim 3 in the adsorption and removal of phosphorus in phosphorus-containing water bodies, characterized in that, The pH of the water body is 5-10.

5. The application of the phosphorus adsorbent composition according to claim 1 in the adsorption and removal of phosphorus in phosphorus-containing water bodies, characterized in that, The particle size ratio of the natural ore to the phosphorus adsorbent is 1:(1~1000).

6. The application of the phosphorus adsorbent composition according to claim 1 in the adsorption and removal of phosphorus in phosphorus-containing water bodies, characterized in that, The phosphorus-containing anions include one or more of the following: orthophosphate ions, polyphosphate ions, pyrophosphate ions, metaphosphate ions, and polymeric organophosphate ions. The natural ore is selected from one or more of zeolite, montmorillonite, sepiolite, bentonite, quartz, diatomite and talc; The phosphorus adsorbent is selected from one or more of activated carbon, lanthanum-modified activated carbon, lanthanum-modified zeolite, and magnesium-modified biochar.

7. The application of the phosphorus adsorbent composition according to any one of claims 1 to 6 in the adsorption and removal of phosphorus in phosphorus-containing water bodies, characterized in that, The total phosphorus concentration in the water body is 1 mg / L to 500 mg / L.

8. A phosphorus adsorbent composition, characterized in that, This includes physically mixed phosphorus adsorbents and natural minerals; The zero-charge point of the natural ore is 1 to 6, and the specific surface area of ​​the natural ore is greater than or equal to 5 m². 2 / g; The volume ratio of the natural ore to the phosphorus adsorbent is (0.1~20):

1.

9. The phosphorus adsorbent composition according to claim 8, characterized in that, The zero charge point of the natural ore is smaller than that of the phosphorus adsorbent. The particle size ratio of the natural ore to the phosphorus adsorbent is 1:(1~1000).

10. The phosphorus adsorbent composition according to claim 8 or 9, characterized in that, The natural ore is selected from one or more of zeolite, montmorillonite, sepiolite, bentonite, quartz, diatomite, and talc.

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