Calcium-manganese-iron composite phosphorus removal adsorbent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of eutrophication treatment, and discloses a calcium-manganese-iron composite phosphorus removal adsorbent as well as a preparation method and application thereof. The preparation method comprises the following steps: mixing a calcium salt solution, a manganese salt solution and a ferric salt solution to obtain a metal salt solution; and under the alkaline condition, mixing the metal salt solution with the carbonate solution, standing and aging to obtain the calcium-manganese-iron composite phosphorus removal adsorbent. The calcium-manganese-iron trimetal composite phosphorus removal adsorbent prepared by the invention can play a multi-metal synergistic phosphorus removal effect, and can quickly reduce the phosphorus content of a water body, so that the proportion of active phosphorus in sediments is reduced, the proportion of inert phosphorus is increased, and the release of phosphorus in the sediments is further inhibited; the additive amount of single metal is reduced, the ecological risk caused by the single-metal phosphorus removal adsorbent is reduced, and the phosphorus removal adsorbent can play a role under different water environment conditions and is wider in application range.

Description

Technical Field

[0001] The invention relates to the technical field of eutrophication treatment, and in particular to a calcium-manganese-iron composite phosphorus removal adsorbent and a preparation method and application thereof. Background Art

[0002] Phosphorus is one of the main elements of eutrophication of water bodies. Total phosphorus is the main pollution indicator in the water environment. The occurrence of cyanobacteria blooms in natural water bodies is closely related to the total phosphorus content of the water body. Therefore, controlling the discharge of phosphorus in wastewater and reducing the phosphorus content in natural water bodies are important components of controlling eutrophication of water bodies.

[0003] Adsorption is an important technical means for deep treatment of phosphorus in wastewater and passivation of endogenous phosphorus in natural water bodies. It has the advantages of high efficiency, economy and easy operation. At present, most commonly used phosphorus adsorbents are clay adsorbents modified by single metals (such as iron, aluminum, calcium, manganese, magnesium, lanthanum, cerium, etc.), and most of them use rare earth elements to improve the phosphorus adsorption effect of the adsorbent. There are disadvantages such as complex preparation methods, high energy consumption, high cost and low adsorption capacity. Moreover, most of the current phosphorus adsorbents have a small pH application range and are only effective under weakly acidic and neutral conditions. The phosphorus adsorption amount drops sharply under alkaline conditions. However, natural water bodies that undergo eutrophication are generally alkaline due to high algae content and strong photosynthesis. The pH of some water bodies with algal blooms may exceed 10, which greatly reduces the effectiveness of the use of phosphorus adsorbents.

[0004] Therefore, there is an urgent need to find a phosphorus removal adsorbent with a wide pH range, high ecological safety and large adsorption capacity. Summary of the invention

[0005] The purpose of the present invention is to provide a calcium-manganese-iron composite phosphorus removal adsorbent and a preparation method and application thereof, so as to solve the problems of existing phosphorus adsorbents such as small pH applicable range, poor ecological safety, and low adsorption capacity.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a calcium-manganese-iron composite phosphorus removal adsorbent, comprising the following steps:

[0008] Mixing the calcium salt solution, the manganese salt solution and the iron salt solution to obtain a metal salt solution;

[0009] Under alkaline conditions, the metal salt solution and the carbonate solution are mixed and allowed to stand for aging to obtain a calcium-manganese-iron composite phosphorus removal adsorbent.

[0010] Preferably, in the preparation method, the calcium salt solution is a calcium chloride solution, the manganese salt solution is a manganese chloride solution, and the iron salt solution is a ferric chloride solution.

[0011] Preferably, in the preparation method, the volume ratio of the calcium salt solution, the manganese salt solution and the iron salt solution is 2-3:0.5-1:0.5-1; the concentrations of the calcium salt solution, the manganese salt solution and the iron salt solution are 0.5-1.5 mol / L, and the concentrations of the calcium salt solution, the manganese salt solution and the iron salt solution are the same.

[0012] Preferably, in the preparation method, the carbonate solution is a sodium carbonate solution or a potassium carbonate solution;

[0013] The volume ratio of the metal salt solution to the carbonate solution is 10-20:1-2.

[0014] Preferably, in the preparation method, the concentration of the carbonate solution is 0.5-1.5 mol / L, and the concentration of the carbonate solution is the same as that of the calcium salt solution.

[0015] Preferably, in the preparation method, the pH value of the alkaline condition is 9-11; the reagent for adjusting the alkaline condition is an alkaline solution, and the alkaline solution includes a sodium hydroxide solution, a potassium hydroxide solution or a calcium hydroxide solution.

[0016] Preferably, in the preparation method, the metal salt solution and the carbonate solution are mixed at a rotation speed of 400 to 600 rpm for a time of 2 to 6 hours.

[0017] Preferably, in the preparation method, the temperature of the static aging is room temperature, and the time is 12 to 36 hours.

[0018] The invention also provides a calcium-manganese-iron composite dephosphorization adsorbent prepared by the preparation method.

[0019] The present invention also provides an application of the calcium-manganese-iron composite dephosphorization adsorbent in dephosphorization of water bodies and inhibition of phosphorus release.

[0020] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The calcium-manganese-iron trimetallic composite phosphorus removal adsorbent prepared by the present invention can exert a multi-metal synergistic phosphorus removal effect, exert a multi-metal composite effect, and reduce the amount of metal release. The prepared calcium-manganese-iron composite phosphorus removal adsorbent can quickly reduce the phosphorus content of the water body, because: calcium salt reacts with phosphate under alkaline conditions to generate a variety of calcium phosphate compound precipitations, and the colloids produced after the hydrolysis of manganese salts and iron salts can flocculate suspended matter in the water and combine with phosphate to produce precipitation. The precipitation produced by the combination of the three can settle quickly, achieving the purpose of rapid phosphorus removal. At the same time, the composite phosphorus removal adsorbent combines with the active phosphorus in the sediment, so that the proportion of active phosphorus (mainly including inorganic phosphorus such as orthophosphate) in the sediment is reduced, and the proportion of inert phosphorus (mainly metal-bound phosphorus) is increased, changing the phosphorus form of the sediment, thereby inhibiting the release of phosphorus in the sediment.

[0022] (2) The calcium-manganese-iron composite phosphorus removal adsorbent prepared by the present invention reduces the amount of single metal added, thereby reducing the ecological risks caused by the excessive amount of single metal ions that may be caused by the single metal phosphorus removal adsorbent.

[0023] (3) The active ingredients in the calcium-manganese-iron composite dephosphorization adsorbent prepared by the present invention can function under different water environment conditions. The substances that play a major role at a lower pH are iron and manganese compounds, and the substances that play a major role at a higher pH are calcium compounds. Under neutral conditions, the three elements of calcium, manganese and iron can all produce a dephosphorization effect. The amount of phosphorus adsorption is less affected by the initial pH of the water body, and the scope of application is wider. In addition, when using the adsorbent prepared by the present invention, the pH of the water body changes less, and the addition of carbonate is crucial. This is because carbonate reacts with calcium hydroxide in the reaction product to form calcium carbonate, thereby reducing the amount of calcium hydroxide in the product and reducing the effect of the adsorbent on the pH of the water body. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments or the prior art are briefly introduced below.

[0025] Figure 1 is the phosphorus adsorption amount of the phosphorus adsorbents of Examples 1 to 3 at different phosphorus concentrations;

[0026] Figure 2 is the phosphorus removal rate of the phosphorus adsorbents of Examples 1 to 3 and Comparative Example 1 at different addition amounts;

[0027] Figure 3 is the phosphorus removal rate of the phosphorus adsorbent of Example 2 and Comparative Example 1 at different initial pH values;

[0028] Figure 4 The changes in total phosphorus content in water samples collected for Application Example 3;

[0029] Figure 5For Application Example 4, the changes in total phosphorus content in the water overlying the pond mud;

[0030] Figure 6 This is Application Example 5: Changes in total phosphorus content in the water overlying the lake mud. DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing a calcium-manganese-iron composite phosphorus removal adsorbent, comprising the following steps:

[0032] Mixing the calcium salt solution, the manganese salt solution and the iron salt solution to obtain a metal salt solution;

[0033] Under alkaline conditions, the metal salt solution and the carbonate solution are mixed and allowed to stand for aging to obtain a calcium-manganese-iron composite phosphorus removal adsorbent.

[0034] In the present invention, the calcium salt solution is preferably a calcium chloride solution.

[0035] In the present invention, the manganese salt solution is preferably a manganese chloride solution.

[0036] In the present invention, the iron salt solution is preferably a ferric chloride solution.

[0037] In the present invention, the calcium salt solution, the manganese salt solution and the iron salt solution are preferably aqueous solutions.

[0038] In the present invention, the concentrations of the calcium salt solution, the manganese salt solution and the iron salt solution are preferably 0.5-1.5 mol / L, more preferably 0.8-1.2 mol / L, more preferably 1 mol / L, and the concentrations of the calcium salt solution, the manganese salt solution and the iron salt solution are the same.

[0039] In the present invention, the volume ratio of the calcium salt solution, the manganese salt solution and the iron salt solution is preferably 2-3: 0.5-1: 0.5-1, more preferably 2.2-2.8: 0.5-0.8: 0.8-1, and more preferably 2.5: 0.5: 1. The reason why the present invention uses calcium chloride, manganese chloride and ferric chloride instead of nitrate is that nitrate will increase the nitrogen content of water and cause nitrogen pollution.

[0040] In the present invention, the parameters for mixing the calcium salt solution, the manganese salt solution and the iron salt solution are not limited, as long as they are mixed evenly.

[0041] In the present invention, the pH value of the alkaline condition is preferably 9 to 11, more preferably 9.5 to 10.5, and more preferably 10. The purpose of adjusting the pH value is to generate a precipitate, which is the main active ingredient of the adsorbent.

[0042] In the present invention, the reagent for adjusting the alkaline condition is preferably an alkaline solution; the alkaline solution is preferably an aqueous solution of an alkali.

[0043] In the present invention, the alkaline solution preferably includes sodium hydroxide solution, potassium hydroxide solution or calcium hydroxide solution, further preferably includes sodium hydroxide solution or potassium hydroxide solution, and more preferably is sodium hydroxide solution.

[0044] In the present invention, the concentration of the alkaline solution is preferably 0.5 to 1.5 mol / L, more preferably 0.8 to 1.2 mol / L, and even more preferably 1 mol / L.

[0045] In the present invention, the method of mixing the metal salt solution with the carbonate solution preferably includes: adding the metal salt solution into the carbonate solution.

[0046] In the present invention, the carbonate solution is preferably an aqueous carbonate solution.

[0047] In the present invention, the carbonate solution is preferably a sodium carbonate solution or a potassium carbonate solution, and more preferably a sodium carbonate solution.

[0048] In the present invention, the concentration of the carbonate solution is preferably 0.5 to 1.5 mol / L, more preferably 0.8 to 1.2 mol / L, and more preferably 1 mol / L, and the concentration of the carbonate solution is the same as that of the calcium salt solution.

[0049] In the present invention, the volume ratio of the metal salt solution to the carbonate solution is preferably 10-20:1-2, more preferably 10-15:1-1.5, and more preferably 10:1.

[0050] In the present invention, the rotation speed of mixing the metal salt solution and the carbonate solution is preferably 400-600 rpm, more preferably 450-550 rpm, more preferably 500 rpm; the time is preferably 2-6 h, more preferably 3-5 h, more preferably 4 h.

[0051] In the present invention, the temperature of the static aging is preferably room temperature; the time is preferably 12 to 36 hours, more preferably 18 to 30 hours, and more preferably 24 hours. The purpose of static aging is to make the generated precipitate more stable.

[0052] In the present invention, after the static aging, post-treatment is preferably further included, and the post-treatment specifically includes: pouring out the supernatant, naturally air-drying or freeze-drying the residue, and sealing and drying it for storage after grinding.

[0053] In the present invention, the post-treatment conditions are not limited, and any method known to those skilled in the art may be used.

[0054] The invention also provides a calcium-manganese-iron composite dephosphorization adsorbent prepared by the preparation method.

[0055] In the present invention, the particle size of the calcium-manganese-iron composite dephosphorization adsorbent is preferably 60-200 meshes, more preferably 80-120 meshes, and even more preferably 100 meshes.

[0056] The present invention also provides an application of the calcium-manganese-iron composite dephosphorization adsorbent in dephosphorization of water bodies and inhibition of phosphorus release.

[0057] In the present invention, the application method is not limited, and any method known to those skilled in the art may be used.

[0058] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] Example 1

[0060] This embodiment provides a method for preparing a calcium-manganese-iron composite phosphorus removal adsorbent, comprising the following steps:

[0061] 1 mol / L calcium chloride aqueous solution, manganese chloride aqueous solution and ferric chloride aqueous solution were prepared respectively, and the calcium chloride aqueous solution, manganese chloride aqueous solution and ferric chloride aqueous solution were mixed evenly in a volume ratio of 3:0.5:0.5 to obtain a metal salt aqueous solution;

[0062] Prepare 1 mol / L sodium carbonate aqueous solution;

[0063] According to the volume fraction, 10 parts of metal salt aqueous solution are slowly added to 1 part of sodium carbonate aqueous solution, the pH of the mixed solution is adjusted to 10 with 1 mol / L sodium hydroxide aqueous solution, and stirred with a magnetic stirrer at 500 rpm for 4 hours, and allowed to stand and age at room temperature for 24 hours; the supernatant is poured out, the residue is naturally air-dried, ground and sealed for dry storage, to obtain a 100-mesh calcium-manganese-iron composite phosphorus removal adsorbent, recorded as CMF1.

[0064] Example 2

[0065] This embodiment provides a preparation method of a calcium-manganese-iron composite dephosphorization adsorbent. The difference from Example 1 is that the volume ratio of calcium chloride aqueous solution, manganese chloride aqueous solution, and ferric chloride aqueous solution is modified to 2.5:0.5:1, and other parameter conditions are the same as those in Example 1. The obtained calcium-manganese-iron composite dephosphorization adsorbent is recorded as CMF2.

[0066] Example 3

[0067] This embodiment provides a preparation method of a calcium-manganese-iron composite dephosphorization adsorbent. The difference from Example 1 is that the volume ratio of calcium chloride aqueous solution, manganese chloride aqueous solution, and ferric chloride aqueous solution is modified to 2:1:1, and other parameter conditions are the same as those in Example 1. The obtained calcium-manganese-iron composite dephosphorization adsorbent is recorded as CMF3.

[0068] Test Example 1

[0069] Potassium dihydrogen phosphate was used to prepare aqueous solutions with phosphorus concentrations of 5, 10, 20, 30, 50, 100, 250, and 500 mg / L, respectively, and the pH was adjusted to 7, and the solutions were divided into 24 conical flasks, each of which was filled with 0.2 L of phosphorus solution. 0.15 g of the phosphorus adsorbents of Examples 1 to 3 were added to the above phosphorus solutions, shaken on a constant temperature shaker for 24 h, and then filtered with a glass fiber filter membrane, the phosphorus content (equilibrium phosphorus concentration) in the filtrate was determined, and the phosphorus adsorption amount (equilibrium phosphorus adsorption amount) of the adsorbent was calculated.

[0070] The Langmuir and Freundlich adsorption isotherm models were used for curve fitting, and the results were as follows: Figure 1 As shown, Figure 1 The results showed that the theoretical maximum phosphorus adsorption capacities of CMF1, CMF2 and CMF3 were 86.2, 141.7 and 50.5 mg / g, respectively.

[0071] Comparative Example 1

[0072] This comparative example provides a commercially available phosphorus lock agent (phosphorus adsorbent), the name of which is lanthanum modified bentonite Denoted as PL, it was purchased from Jiangsu Jinxin Environmental Engineering Co., Ltd.

[0073] Application Example 1

[0074] Potassium dihydrogen phosphate was used to prepare an aqueous solution with a phosphorus concentration of 10 mg / L, and its pH was adjusted to 7, and the solution was dispensed into 40 conical flasks, each of which was filled with 0.2 L of phosphorus solution. 0.025 g, 0.05 g, 0.1 g, 0.15 g, and 0.2 g of the phosphorus adsorbent of Examples 1 to 3 or Comparative Example 1 were added thereto, respectively. Each experiment was repeated once, and the solution was placed on a constant temperature shaker for 24 hours, and then filtered with a glass fiber filter membrane, the phosphorus content in the filtrate was determined, and the phosphorus removal rate was calculated.

[0075] The test results of application example 1 are as follows: Figure 2 shown. Figure 2 The results showed that the phosphorus removal efficiencies of CMF1, CMF2 and CMF3 adsorbents were much higher than those of the phosphorus lock agent PL.

[0076] Application Example 2

[0077] Potassium dihydrogen phosphate was used to prepare an aqueous solution with a phosphorus concentration of 5 mg / L, and the pH was adjusted to 3, 5, 7, 9, and 11, respectively, and the solution was dispensed into multiple conical flasks, each of which was filled with 0.2 L of phosphorus solution. 0.1 g of the phosphorus adsorbent of Example 2 or Comparative Example 1 was added, and each experiment was repeated once, placed on a constant temperature shaker for 24 hours, and then filtered with a glass fiber filter membrane, the phosphorus content in the filtrate was determined, and the phosphorus removal rate was calculated.

[0078] The test results of application example 2 are as follows: Figure 3 shown. Figure 3 The results show that the phosphorus removal rate of CMF2 is higher than 97% when the initial pH of the phosphorus solution is in the range of 3 to 11, and the phosphorus removal rate of the phosphorus lock agent PL is high only in the pH range of 5 to 7, and the removal rate is lower under other pH conditions.

[0079] Application Example 3

[0080] On June 12, 2023, water samples were collected from the tailwater discharge lake area of ​​Gongqingcheng Sewage Treatment Plant and divided into cylindrical glass containers with a diameter of 16 cm and a height of 24 cm. The initial total phosphorus content in the water sample was 0.524 mg / L, and the initial pH was 7.8. The water samples were divided into 3 groups, among which the control group was not treated in any way, 1g of the phosphorus adsorbent of Example 2 was added to the CMF treatment group, and 1g of the phosphorus lock agent (PL) of Comparative Example 1 was added to the PL treatment group, and the total phosphorus content in the water samples was regularly measured (an equal amount of pure water was added after taking the water sample).

[0081] Application Example 3 The results of the 29-day test are as follows Figure 4 shown. Figure 4 The results showed that compared with the control group, CMF2 and phosphorus lock agent (PL) can effectively adsorb phosphorus in the water and can maintain it for a longer time, and the difference in phosphorus removal effect between the two is relatively small.

[0082] Application Example 4

[0083] On July 25, 2023, sediments (total phosphorus content of 0.81 mg / g) were collected from aquaculture ponds around the Gongqingcheng sewage treatment plant and evenly divided into cylindrical glass containers with a diameter of 16 cm and a height of 24 cm (filling thickness of 5 cm), and then 15 cm of pure water was slowly added as overlying water, which was stabilized for 3 days. The samples were divided into 3 groups, among which the control group was not treated in any way, 15 g of the phosphorus adsorbent of Example 2 was added to the CMF treatment group, and 15 g of the phosphorus lock agent of Comparative Example 1 was added to the phosphorus lock agent treatment group, and the total phosphorus content in the pond mud overlying water was regularly measured.

[0084] The results of the 34-day test in Application Example 4 are as follows Figure 5 shown. Figure 5The results showed that CMF2 could effectively inhibit the release of phosphorus from pond mud and could maintain this effect for a long time; the phosphorus-locking agent could only inhibit the release of phosphorus from pond mud and its effect was worse than that of CMF2.

[0085] Application Example 5

[0086] On July 25, 2023, sediments (total phosphorus content of 2.66 mg / g) were collected from the tailwater discharge lake area of ​​Gongqingcheng Sewage Treatment Plant and evenly divided into cylindrical glass containers with a diameter of 16 cm and a height of 24 cm (filling thickness of 5 cm), and then 15 cm of pure water was slowly added as overlying water for 3 days. The samples were divided into 3 groups, among which the control group was not treated in any way, 15 g of the phosphorus adsorbent of Example 2 was added to the CMF treatment group, and 15 g of the phosphorus lock agent of Comparative Example 1 was added to the phosphorus lock agent treatment group, and the total phosphorus content in the overlying water of the lake mud was regularly measured.

[0087] The results of the 34-day test in Application Example 5 are as follows Figure 6 shown. Figure 6 The results show that CMF2 can effectively inhibit the release of phosphorus from lake mud and can maintain it for a long time; the phosphorus lock agent can only inhibit the release of phosphorus from lake mud, and the effect is worse than CMF2.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a calcium-manganese-iron composite phosphorus removal adsorbent, characterized in that: The following steps are involved: Mixing the calcium salt solution, the manganese salt solution and the iron salt solution to obtain a metal salt solution; Under alkaline conditions, the metal salt solution and the carbonate solution are mixed and allowed to stand for aging to obtain a calcium-manganese-iron composite phosphorus removal adsorbent.

2. The preparation method according to claim 1, characterized in that: The calcium salt solution is a calcium chloride solution, the manganese salt solution is a manganese chloride solution, and the iron salt solution is a ferric chloride solution.

3. The preparation method according to claim 1 or 2, characterized in that: The volume ratio of the calcium salt solution, the manganese salt solution and the iron salt solution is 2-3:0.5-1:0.5-1; the concentrations of the calcium salt solution, the manganese salt solution and the iron salt solution are 0.5-1.5 mol / L, and the concentrations of the calcium salt solution, the manganese salt solution and the iron salt solution are the same.

4. The preparation method according to claim 3, characterized in that: The carbonate solution is a sodium carbonate solution or a potassium carbonate solution; The volume ratio of the metal salt solution to the carbonate solution is 10-20:1-2.

5. The preparation method according to claim 1 or 4, characterized in that: The concentration of the carbonate solution is 0.5-1.5 mol / L, and the concentration of the carbonate solution is the same as that of the calcium salt solution.

6. The preparation method according to claim 5, characterized in that: The pH value of the alkaline condition is 9-11; the reagent for adjusting the alkaline condition is an alkaline solution, and the alkaline solution includes a sodium hydroxide solution, a potassium hydroxide solution or a calcium hydroxide solution.

7. The preparation method according to claim 1 or 6, characterized in that: The metal salt solution and the carbonate solution are mixed at a rotation speed of 400 to 600 rpm for 2 to 6 hours.

8. The preparation method according to claim 7, characterized in that: The temperature of the static aging is room temperature, and the time is 12 to 36 hours.

9. The calcium-manganese-iron composite phosphorus removal adsorbent prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the calcium-manganese-iron composite phosphorus removal adsorbent according to claim 9 in removing phosphorus from water and inhibiting phosphorus release.

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