A slow-release phosphorus removal material and its preparation method and application

Abstract

The invention discloses a slow-release phosphorus removal material and a preparation method and application thereof, which belongs to the technical field of sewage treatment, and comprises the following components by mass: 40-55 parts of calcium peroxide, 25-35 parts of a binder, 2-5 parts of bentonite, 5-20 parts of calcined oyster shell powder, and 10-25 parts of modified red clay loaded with iron; the binder comprises silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1: (0.2-1): (0.1-0.8). Under the synergistic effect of calcium peroxide, a binder, bentonite, calcined oyster shell powder and modified red clay loaded with iron, the present invention can not only be used as a phosphorus removal filter material, but also can be used alone or in combination with filter bed filter materials such as quartz sand and gravel, directly used as filter material for filter pools, wetlands, etc., to permanently remove phosphorus in surface water, and can also be directly put into rivers, lakes and ponds to control the release of endogenous phosphorus, and the preparation cost is low, and it has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a slow-release phosphorus removal material and a preparation method and application thereof. Background Art

[0002] The sources of total phosphorus pollution in surface water bodies such as rivers, lakes, reservoirs and ponds include external input and internal release. External input includes industrial wastewater, urban and rural domestic wastewater, agricultural runoff and aquaculture tailwater, as well as atmospheric deposition. Internal release refers to the formation of a sediment pollution layer after pollutants are deposited. The polluted sediment acts as a "source" and continuously releases phosphates to the overlying water body. Studies have shown that the dynamic release of phosphorus from the sediment of Taihu Lake is 2-6 times the external input. Reducing or controlling the release of endogenous phosphorus is also critical to the control of total phosphorus in water bodies.

[0003] For exogenous input, the mainstream methods for removing and recovering phosphorus resources from sewage or tailwater include physical filtration, chemical adsorption and biofilm method. Due to its relatively low cost, simple operation and stable phosphorus removal performance, chemical adsorption has been widely accepted. Mature products such as polyaluminium chloride (PAC) and ferrous sulfate (PFS) have been widely used in centralized domestic sewage treatment plants and industrial sewage treatment facilities with excellent phosphorus removal performance. However, both iron salts and aluminium salts have considerable environmental safety risks, which limits their application in mobile surface water bodies. At present, there are also some environmentally friendly filter media products, such as patent CN202310165925.0, which mixes calcium salts such as gypsum powder and quicklime powder with auxiliary materials and adds a foaming agent to make a porous phosphorus removal material, which can quickly remove phosphate from surface water while avoiding secondary release of phosphate. CN201810556287.4 loads lanthanide compounds onto the surface of bentonite, and then mixes and solidifies them with chitosan, iron oxide, etc. to obtain lanthanide magnetic phosphorus removal materials with large adsorption capacity and convenient recycling and reuse.

[0004] The current mainstream for the release of endogenous phosphorus from sediment is in-situ covering technology and phosphorus control technology. By adding covering materials or adsorbent materials to the sediment in a directional manner, the release of total phosphorus from the sediment is prevented or the phosphate released from the sediment is adsorbed at the mud-water interface, which can reduce the risk of endogenous total phosphorus release to the overlying water body. Patent CN201710012038.4 sequentially lays zeolite, zero-valent iron, heavy metal solidified filler, activated carbon and sand to prevent the release of phosphorus from the sediment.

[0005] Judging from the current application results, most river water phosphorus removal materials cannot meet the demand. For example, the adsorption capacity of activated carbon is too low, the cost of lanthanide materials is too high, and the release rate of calcium salt materials is too fast. All of them cannot achieve the goal of long-term effectiveness after being put into use. In terms of endogenous phosphorus release control, there are two outstanding problems in the application of covering materials. One is that the permeability coefficient of most covering materials is too high, and pollutants such as phosphates are easy to penetrate, and the barrier effect cannot be sustained. The second is the problem of erosion resistance. It is easy to be eroded and lost during the flood season. In terms of phosphorus adsorption materials, lanthanum bentonite-based phosphorus locking products represented by phoslock have been widely used and have achieved good application results. However, because it is a powdered material, there is still a problem that lanthanum salts are released too quickly and the effect is short-lived.

[0006] In view of this, this application is filed. Summary of the invention

[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a slow-release phosphorus removal material and a preparation method and application thereof. The material has excellent phosphorus removal effect and slow-release effect.

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] A slow-release phosphorus removal material comprises the following components in parts by weight: 40-55 parts of calcium peroxide, 25-35 parts of a binder, 2-5 parts of bentonite, 5-20 parts of calcined oyster shell powder, and 10-25 parts of iron-loaded modified red clay;

[0010] The binder comprises silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1: (0.2-1): (0.1-0.8).

[0011] The present invention creatively combines the above-mentioned raw materials, and under the synergistic effect of calcium peroxide, binder, bentonite, calcined oyster shell powder, and iron-loaded modified red clay, significantly improves the phosphorus removal effect and slow-release effect. The slow-release phosphorus removal material can meet the needs of river water phosphorus removal and endogenous phosphorus control. The slow-release phosphorus removal material can not only be used as phosphorus removal filter material, but also can be directly used as filter material for filter pools, wetlands, etc., alone or in combination with filter bed filter materials such as quartz sand and gravel, to permanently remove phosphorus in surface water. It can also be directly put into rivers, lakes and ponds to control the release of endogenous phosphorus, and the preparation cost is low, so it has broad application prospects.

[0012] The slow-release phosphorus removal material of the present invention is formed by compounding a variety of inorganic salt materials, has an interconnected microporous skeleton structure, a large specific surface area, and mild interfacial chemical properties. After being put into water, it will mainly slowly release calcium ions, as well as phosphorus removal components such as iron, magnesium and aluminum according to the change of phosphate concentration in the water body. Calcium, iron, magnesium and aluminum ions will react with phosphate in the water to form insoluble salt precipitation, thereby achieving the removal of total phosphorus. The material is alkaline, and when phosphate passes through alkaline particles, it will quickly form insoluble phosphate precipitation, thereby significantly reducing the phosphorus content.

[0013] The present invention creatively uses silicate cement, polyacrylic acid and hydroxypropyl methyl cellulose ether as a binder according to the above-mentioned specific ratio. After the cement is solidified (subsequent drying or curing can achieve solidification), the release rate of calcium, iron, magnesium and aluminum ions in the system can be effectively improved, and the strength of the system can be improved. At the same time, the cement can react with phosphate ions in water to remove phosphorus elements in water; PAA (polyacrylic acid) can electrostatically adsorb and chelate with calcium ions and phosphate ions in water. It promotes the adsorption and precipitation formation of phosphate ions and provides active sites. Polyacrylic acid can regulate the release rate of ions in water and can form a colloidal network with the hydroxypropyl methyl cellulose ether in water to achieve a continuous and stable release effect. When silicate cement, polyacrylic acid and hydroxypropyl methyl cellulose ether are used in combination, the three can work synergistically to further enhance the phosphorus removal effect and sustained release effect.

[0014] As a preferred embodiment of the present invention, the binder includes silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1: (0.4-0.8): (0.2-0.6), especially when the mass ratio of the three is within this range, the phosphorus removal effect and sustained release effect can be further improved.

[0015] As a preferred embodiment of the present invention, the mass ratio of the calcined oyster shell powder and the iron-loaded modified red clay is 1: (1-2). In particular, when the mass ratio of the two is controlled within this range, a release balance of iron and calcium can be achieved while providing a larger adsorption capacity, thereby further improving the adsorption effect of phosphorus.

[0016] As a preferred embodiment of the present invention, the method for preparing the iron-loaded modified red clay comprises the following steps:

[0017] Adding red clay, zinc oxide, rubidium hydroxide and sodium dodecylbenzene sulfonate into a sulfuric acid solution, stirring evenly, drying, heat treating at 800-900°C for 2-5h, washing and drying to obtain pretreated red clay;

[0018] The pretreated red clay is added to the ferrous sulfate solution, stirred evenly, then sodium borohydride is added, stirred evenly, then sodium alginate and polyvinyl alcohol are added, stirred evenly at 65-85° C., ultrasonically treated, and dried to obtain the modified red clay loaded with iron.

[0019] The invention uniformly mixes red clay, zinc oxide, rubidium hydroxide and sodium dodecylbenzene sulfonate in a sulfuric acid solution; in a heat treatment process, the zinc oxide forms pores in the red clay, and the rubidium hydroxide etches the red clay, thereby effectively improving the porosity and specific surface area of ​​the red clay and the phosphorus removal effect; and by improving the pore structure of the red clay, the smoothness of ion release is improved, the activity of the red clay is effectively improved, the contact sites are increased, and then iron is loaded, and then the ion release rate is further controlled through treatment with sodium alginate and polyvinyl alcohol, thereby effectively improving the slow-release effect and the phosphorus removal effect.

[0020] As a preferred embodiment of the present invention, the particle size of the red clay is 200-600 mesh.

[0021] As a preferred embodiment of the present invention, the mass ratio of the red clay, zinc oxide, rubidium hydroxide, sodium dodecylbenzene sulfonate and sulfuric acid solution is 1: (0.2-0.4): (0.1-0.3): (0.05-0.2): (4-20).

[0022] As a preferred embodiment of the present invention, the mass ratio of the pretreated red soil, ferrous sulfate solution, sodium borohydride, sodium alginate and polyvinyl alcohol is 1: (4-20): (0.1-0.3): (0.05-0.2): (0.05-0.2).

[0023] As a preferred embodiment of the present invention, the concentration of the sulfuric acid solution is 0.1-2 mol / L; and / or

[0024] The concentration of the ferrous sulfate solution is 0.1-2 mol / L.

[0025] As a preferred embodiment of the present invention, the calcined oyster shell powder is obtained by calcining oyster shell powder at 350-420°C and 650-720°C in sequence.

[0026] As a preferred embodiment of the present invention, the preparation method of the calcined oyster shell powder is: calcining the oyster shell powder at 350-420°C for 40-80 min, and then calcining at 650-720°C for 40-80 min to obtain the calcined oyster shell powder.

[0027] Among them, the iron-loaded modified red clay can slowly release iron, thereby continuously reacting with phosphate ions in the water to ensure long-term dephosphorization. At the same time, its special pore structure and high specific surface area can effectively adsorb phosphorus. Sodium alginate and polyvinyl alcohol control the release rate of iron to avoid rapid dissolution of iron ions and improve the slow-release effect. The calcium in the calcined oyster shell powder can chemically react with the phosphate ions in the water to remove phosphorus from the water. The two use different elemental properties (the iron-loaded modified red clay is mainly iron, and the calcined oyster shell powder is mainly calcium). At the same time, both have high activity, high specific surface area and special pore structure, so as to achieve synergistic phosphorus removal effects from different angles.

[0028] As a preferred embodiment of the present invention, the compressive strength of the silicate cement is ≥32.5 MPa.

[0029] Among them, the compressive strength of silicate cement is carried out according to the national standard GB / T 17671 "Test method for strength of cement mortar (ISO method)".

[0030] As a preferred embodiment of the present invention, the particle size of the calcium peroxide is 80-200 mesh.

[0031] The particle size of the bentonite is 80-200 meshes.

[0032] The present invention also provides a method for preparing a slow-release phosphorus removal material, comprising the following steps:

[0033] Calcium peroxide, a binder, bentonite, calcined oyster shell powder, and iron-loaded modified red clay are uniformly mixed, the mixture is added into a granulator, sprayed with water for granulation, particles with a particle size of 2 to 8 mm are sieved out, and the particles are dried or cured to obtain a slow-release phosphorus removal material.

[0034] As a preferred embodiment of the present invention, the amount of atomized water added is 5-8wt% of the mixture.

[0035] As a preferred embodiment of the present invention, the granulator is a disc granulator, and the disc forms an angle of 30°-65° with the horizontal plane.

[0036] As a preferred embodiment of the present invention, the rotation speed of the disc granulator is 60r / min-120r / min.

[0037] As a preferred embodiment of the present invention, the curing time is 3 to 5 days.

[0038] As a preferred embodiment of the present invention, the drying temperature is 60-100° C. and the drying time is 1-5 hours.

[0039] The invention also provides an application of a slow-release phosphorus removal material in sewage treatment.

[0040] The beneficial effects of the present invention are: (1) under the synergistic effect of calcium peroxide, binder, bentonite, calcined oyster shell powder, and iron-loaded modified red clay, the present invention significantly improves the phosphorus removal effect and slow-release effect. The slow-release phosphorus removal material can meet the needs of river water phosphorus removal and endogenous phosphorus control. The slow-release phosphorus removal material can not only be used as a phosphorus removal filter material, but also can be used alone or in combination with quartz sand, gravel and other filter bed filter materials, directly used as filter materials for filter pools, wetlands, etc. to permanently remove phosphorus from surface water. It can also be directly put into rivers, lakes and ponds to control the release of endogenous phosphorus. It has low preparation cost and broad application prospects.

[0041] (2) The slow-release phosphorus removal material of the present invention is formed by compounding a variety of inorganic salt materials, has an interconnected microporous skeleton structure, a large specific surface area, and mild interfacial chemical properties. After being put into water, it will mainly slowly release calcium ions, as well as phosphorus removal components such as iron, magnesium and aluminum according to the change of phosphate concentration in the water body. Calcium, iron, magnesium and aluminum ions will react with phosphate in the water to form insoluble salt precipitation, thereby achieving the removal of total phosphorus. The material is alkaline, and when phosphate passes through the alkaline particles, it will quickly form insoluble phosphate precipitation, thereby significantly reducing the phosphorus content. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is the slow-release phosphorus removal material prepared in Example 1. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application are described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0044] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0045] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0046] In the present application, there is no particular limitation on the specific dispersion and stirring treatment methods.

[0047] Unless otherwise specified, the components, raw materials or instruments used in the embodiments and comparative examples of the present invention are all commercially available raw materials or instruments, and the components and raw materials used in each parallel experiment are all of the same kind.

[0048] The following examples are provided to facilitate understanding of the present invention. These examples are not provided to limit the scope of the claims.

[0049] Example 1

[0050] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of modified red clay loaded with iron.

[0051] The binder comprises silicate cement, polyacrylic acid (polyacrylic acid, molecular weight 5000) and hydroxypropyl methylcellulose ether in a mass ratio of 1:0.4:0.6.

[0052] The mass ratio of the calcined oyster shell powder to the iron-loaded modified red clay is 1:2.

[0053] The method for preparing the iron-loaded modified red clay comprises the following steps:

[0054] Add 200-mesh red clay, zinc oxide, rubidium hydroxide and sodium dodecylbenzene sulfonate to a 0.5 mol / L sulfuric acid solution, stir evenly at 200 rpm, dry at 90°C for 2 h, heat treat at 850°C for 4 h, wash with 0.5 mol / L hydrochloric acid solution until neutral, and dry at 90°C for 4 h to obtain pretreated red clay; the mass ratio of the red clay, zinc oxide, rubidium hydroxide, sodium dodecylbenzene sulfonate and sulfuric acid solution is 1:0.3:0.2:0.1:10.

[0055] The pretreated red soil was added to a 0.5 mol / L ferrous sulfate solution, stirred at 200 rpm, sodium borohydride was added, stirred at 200 rpm, sodium alginate and polyvinyl alcohol (PVA1788) were added, stirred at 80°C at 200 rpm, ultrasonically treated at 400 W for 30 minutes, and finally dried at 90°C for 5 hours to obtain iron-loaded modified red soil. The mass ratio of the pretreated red soil, ferrous sulfate solution, sodium borohydride, sodium alginate, and polyvinyl alcohol was 1:10:0.2:0.1:0.1.

[0056] The preparation method of the calcined oyster shell powder is as follows: calcining 200-mesh oyster shell powder at 400° C. for 60 minutes, and then calcining at 700° C. for 60 minutes to obtain the calcined oyster shell powder.

[0057] The particle size of the calcium peroxide is 100 mesh, and the particle size of the bentonite is 100 mesh.

[0058] Wherein, the silicate cement is Albow brand P.W42.5 grade white silicate cement.

[0059] The method for preparing the slow-release phosphorus removal material comprises the following steps:

[0060] Calcium peroxide, binder, bentonite, calcined oyster shell powder, and modified red clay loaded with iron are mixed evenly, and the mixture is added to a disc granulator, the angle between the disc of the disc granulator and the horizontal plane is 45°, the rotation speed of the disc granulator is 100rpm, and sprayed water is used for granulation, and particles with a particle size of 2-8mm are screened out to obtain a slow-release phosphorus removal material. The amount of atomized water added is 6wt% of the mixture.

[0061] Among them, the slow-release phosphorus removal material prepared in this embodiment is as follows Figure 1 shown.

[0062] Example 2

[0063] The difference between Example 2 and Example 1 is that the mass ratios of calcined oyster shell powder and iron-loaded modified red clay are different, and the others are the same.

[0064] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 15 parts of calcined oyster shell powder, and 15 parts of modified red clay loaded with iron.

[0065] The mass ratio of the calcined oyster shell powder to the iron-loaded modified red clay is 1:1.

[0066] Example 3

[0067] The difference between Example 3 and Example 1 is that the mass ratio of calcined oyster shell powder and iron-loaded modified red clay is different, and the others are the same.

[0068] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 20 parts of calcined oyster shell powder, and 10 parts of modified red clay loaded with iron.

[0069] The mass ratio of the calcined oyster shell powder to the iron-loaded modified red clay is 1:0.5.

[0070] Example 4

[0071] The difference between Example 4 and Example 1 is that the mass ratio of calcined oyster shell powder and iron-loaded modified red clay is different, and the others are the same.

[0072] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 5 parts of calcined oyster shell powder, and 25 parts of modified red clay loaded with iron.

[0073] The mass ratio of the calcined oyster shell powder to the iron-loaded modified red clay is 1:5.

[0074] Example 5

[0075] The difference between Example 5 and Example 1 is that the mass ratio of the binder is different, and the other parts are the same.

[0076] The binder comprises silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1:0.8:0.2.

[0077] Example 6

[0078] The difference between Example 6 and Example 1 is that the mass ratio of the binder is different, and the other parts are the same.

[0079] The binder comprises silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1:0.2:0.8.

[0080] Example 7

[0081] The difference between Example 7 and Example 1 is that the mass ratio of the binder is different, and the other parts are the same.

[0082] The binder comprises silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1:1:0.1.

[0083] Example 8

[0084] The difference between Example 8 and Example 1 is that the amount of raw materials used is different, and everything else is the same.

[0085] A slow-release phosphorus removal material comprises the following components in parts by mass: 40 parts of calcium peroxide, 35 parts of a binder, 2 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of modified red clay loaded with iron.

[0086] The mass ratio of the calcined oyster shell powder to the iron-loaded modified red clay is 1:2.

[0087] Example 9

[0088] The difference between Example 9 and Example 1 is that the amount of raw materials used is different, and everything else is the same.

[0089] A slow-release phosphorus removal material comprises the following components in parts by mass: 55 parts of calcium peroxide, 25 parts of a binder, 5 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of iron-loaded modified red clay.

[0090] The mass ratio of the calcined oyster shell powder to the iron-loaded modified red clay is 1:2.

[0091] Example 10

[0092] The difference between Example 10 and Example 1 is that the preparation parameters of the iron-loaded modified red clay are different, and the other parameters are the same.

[0093] The method for preparing the iron-loaded modified red clay comprises the following steps:

[0094] Add 200-mesh red clay, zinc oxide, rubidium hydroxide and sodium dodecylbenzene sulfonate to a 0.5 mol / L sulfuric acid solution, stir evenly at 200 rpm, dry at 90°C for 2 h, heat treat at 850°C for 4 h, wash with 0.5 mol / L hydrochloric acid solution to neutrality, and dry at 90°C for 4 h to obtain pretreated red clay; the mass ratio of the red clay, zinc oxide, rubidium hydroxide, sodium dodecylbenzene sulfonate and sulfuric acid solution is 1:0.2:0.3:0.05:10.

[0095] The pretreated red soil was added to a 0.5 mol / L ferrous sulfate solution, stirred at 200 rpm, sodium borohydride was added, stirred at 200 rpm, sodium alginate and polyvinyl alcohol were added, stirred at 80°C at 200 rpm, ultrasonically treated at 400 W for 30 min, and finally dried at 90°C for 5 h to obtain iron-loaded modified red soil. The mass ratio of the pretreated red soil, ferrous sulfate solution, sodium borohydride, sodium alginate, and polyvinyl alcohol was 1:10:0.1:0.2:0.05.

[0096] Embodiment 11

[0097] The difference between Example 11 and Example 1 is that the preparation parameters of the iron-loaded modified red clay are different, and the other parameters are the same.

[0098] The method for preparing the iron-loaded modified red clay comprises the following steps:

[0099] Add 200-mesh red clay, zinc oxide, rubidium hydroxide and sodium dodecylbenzene sulfonate to a 0.5 mol / L sulfuric acid solution, stir evenly at 200 rpm, dry at 90°C for 2 h, heat treat at 850°C for 4 h, wash with 0.5 mol / L hydrochloric acid solution until neutral, and dry at 90°C for 4 h to obtain pretreated red clay; the mass ratio of the red clay, zinc oxide, rubidium hydroxide, sodium dodecylbenzene sulfonate and sulfuric acid solution is 1:0.4:0.1:0.2:10.

[0100] The pretreated red soil was added to a 0.5 mol / L ferrous sulfate solution, stirred at 200 rpm, sodium borohydride was added, stirred at 200 rpm, sodium alginate and polyvinyl alcohol were added, stirred at 80°C at 200 rpm, ultrasonically treated at 400 W for 30 min, and finally dried at 90°C for 5 h to obtain iron-loaded modified red soil. The mass ratio of the pretreated red soil, ferrous sulfate solution, sodium borohydride, sodium alginate, and polyvinyl alcohol was 1:10:0.3:0.05:0.2.

[0101] Comparative Example 1

[0102] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not contain calcined oyster shell powder, and the other contents are the same.

[0103] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, and 20 parts of modified red clay loaded with iron.

[0104] Comparative Example 2

[0105] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 does not contain modified red clay loaded with iron, and the other aspects are the same.

[0106] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, and 10 parts of calcined oyster shell powder.

[0107] Comparative Example 3

[0108] The difference between Comparative Example 3 and Example 1 is that Comparative Example 3 uses an equal amount of calcined oyster shell powder to replace the iron-loaded modified red clay, and the other contents are the same.

[0109] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, and 30 parts of calcined oyster shell powder.

[0110] Comparative Example 4

[0111] The difference between Comparative Example 4 and Example 1 is that Comparative Example 4 uses modified laterite with an equal amount of iron loading to replace the calcined oyster shell powder, and the other contents are the same.

[0112] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, and 30 parts of modified red clay loaded with iron.

[0113] Comparative Example 5

[0114] The difference between Comparative Example 5 and Example 1 is that Comparative Example 5 uses an equal amount of 200-mesh red clay to replace the iron-loaded modified red clay.

[0115] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of red clay.

[0116] Comparative Example 6

[0117] The difference between Comparative Example 6 and Example 1 is that the preparation method of the iron-loaded modified red clay in Comparative Example 6 is different from that in Example 1, and the others are the same.

[0118] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of modified red clay loaded with iron.

[0119] The method for preparing the iron-loaded modified red clay comprises the following steps:

[0120] Add 200 mesh red clay to 0.5 mol / L ferrous sulfate solution, stir evenly at 200 rpm, then add sodium borohydride, stir evenly at 200 rpm, then add sodium alginate and polyvinyl alcohol, stir evenly at 80°C at 200 rpm, ultrasonically treat for 30 min at 400 W, and finally dry at 90°C for 5 h to obtain iron-loaded modified red clay. The mass ratio of the pretreated red clay, ferrous sulfate solution, sodium borohydride, sodium alginate, and polyvinyl alcohol is 1:10:0.2:0.1:0.1.

[0121] Comparative Example 7

[0122] The difference between Comparative Example 7 and Example 1 is that the preparation method of the modified red clay in Comparative Example 7 is different from that in Example 1, and the others are the same.

[0123] The method for preparing the iron-loaded modified red clay comprises the following steps:

[0124] Add 200-mesh red clay, zinc oxide, rubidium hydroxide and sodium dodecylbenzene sulfonate to a 0.5 mol / L sulfuric acid solution, stir evenly at 200 rpm, dry at 90°C for 2 hours, heat treat at 850°C for 4 hours, wash with 0.5 mol / L hydrochloric acid solution to neutrality, and dry at 90°C for 4 hours to obtain modified red clay; the mass ratio of the red clay, zinc oxide, rubidium hydroxide, sodium dodecylbenzene sulfonate and sulfuric acid solution is 1:0.3:0.2:0.1:10.

[0125] Comparative Example 8

[0126] The difference between Comparative Example 8 and Example 1 is that the binder of Comparative Example 8 is a single silicate cement, and the others are the same.

[0127] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of modified red clay loaded with iron.

[0128] The binder is silicate cement.

[0129] Comparative Example 9

[0130] The difference between Comparative Example 9 and Example 1 is that the binder of Comparative Example 9 is a single polyacrylic acid, and the other parts are the same.

[0131] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of modified red clay loaded with iron.

[0132] The binder is polyacrylic acid.

[0133] Comparative Example 10

[0134] The difference between Comparative Example 10 and Example 1 is that the binder in Comparative Example 10 is a single hydroxypropyl methylcellulose ether, and the other parts are the same.

[0135] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of modified red clay loaded with iron.

[0136] The binder is hydroxypropyl methylcellulose ether.

[0137] In this comparative example, the amount of hydroxypropyl methylcellulose ether used was too much and granulation was impossible.

[0138] Comparative Example 11

[0139] The difference between Comparative Example 11 and Example 1 is that the mass ratio of the binder in Comparative Example 11 is not within the scope of the present invention, and the others are the same.

[0140] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of modified red clay loaded with iron.

[0141] The binder comprises silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1:2:0.05.

[0142] Comparative Example 12

[0143] The difference between Comparative Example 12 and Example 1 is that the mass ratio of the binder in Comparative Example 12 is not within the scope of the present invention, and the others are the same.

[0144] A slow-release phosphorus removal material comprises the following components in parts by mass: 44 parts of calcium peroxide, 32 parts of a binder, 4 parts of bentonite, 10 parts of calcined oyster shell powder, and 20 parts of modified red clay loaded with iron.

[0145] The binder comprises silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1:0.1:1.5.

[0146] Test Case

[0147] 1. Phosphorus removal effect test.

[0148] Prepare 250 ml of simulated phosphorus-containing wastewater with a concentration of 50 mg / L, and treat it with the materials of the embodiment and the comparative example (the addition amount is 0.5wt%) respectively (three groups of each embodiment and comparative example were measured and the average value was taken), set the temperature to 25°C, the speed to 250 rpm, and oscillate at a constant temperature for 24 h. Take the supernatant and filter it with a 0.45μm filter membrane, and calculate the phosphorus removal rate.

[0149] 2. Sustained release effect test.

[0150] Characterizing sustained-release effects by calcium and iron release

[0151] Weigh 10 g of each material (three groups were measured for each embodiment and comparative example, and the average value was taken), add them into a conical flask, add 250 ml of deionized water and let it stand and seal; take the supernatant at intervals of 10 days, filter it with a 0.45 μm filter membrane, and determine the concentrations of calcium and iron in the solution. After the determination, replace the deionized water in the conical flask immediately; calculate the total release amount A1 (in mg / d) of calcium and iron of each material in 10 days.

[0152] The deionized water in the conical flask was replaced every 10 days, and the total calcium and iron release A2 (in mg / d) of the material was calculated on the 80th day.

[0153] Calculate the sustained release rate, sustained release rate = 100%*(A2 / A1).

[0154] Table 1

[0155]

[0156] It can be seen from Table 1 that the material of the present invention has excellent sustained-release effect and phosphorus removal effect.

[0157] By comparing Example 1 with Comparative Examples 1 to 4, it can be seen that the calcined oyster shell powder and the modified red clay loaded with iron described in the present invention have a significant synergistic effect in phosphorus removal. Under the synergistic effect of the two, the phosphorus removal effect is significantly improved. The lack of one of them (the addition amount is the same during the test) will lead to a significant decrease in the phosphorus removal effect, and the modified red clay loaded with iron has a significant sustained release effect.

[0158] By comparing Example 1 with Comparative Examples 5 to 7, it can be seen that the iron-loaded modified red clay prepared by the preparation method of the present invention can significantly improve the phosphorus removal effect and has an excellent slow-release effect.

[0159] By comparing Example 1 with Comparative Examples 8 to 12, it can be seen that the binder of the present invention can significantly improve the sustained-release effect, and the binder can also improve the phosphorus removal effect to a certain extent.

[0160] Comparative Examples 1 to 4 show that by controlling the mass ratio of calcined oyster shell powder to iron-loaded modified red clay to 1: (1 to 2), the phosphorus removal effect and the slow-release effect are effectively improved.

[0161] By comparing Example 1 with Examples 5 to 7, it can be seen that the present invention uses silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1: (0.4 to 0.8): (0.2 to 0.6), which further improves the sustained-release effect.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A slow-release phosphorus removal material, characterized in that: The invention comprises the following components in parts by weight: 40 to 55 parts of calcium peroxide, 25 to 35 parts of a binder, 2 to 5 parts of bentonite, 5 to 20 parts of calcined oyster shell powder and 10 to 25 parts of modified red clay loaded with iron; The binder comprises silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1: (0.2-1): (0.1-0.8); The mass ratio of the calcined oyster shell powder to the iron-loaded modified red clay is 1:(1-2); The preparation method of the iron-loaded modified red clay comprises the following steps: Adding red clay, zinc oxide, rubidium hydroxide and sodium dodecylbenzene sulfonate into a sulfuric acid solution, stirring evenly, drying, heat treating at 800-900°C for 2-5h, washing, and drying to obtain pretreated red clay; The pretreated red clay is added to the ferrous sulfate solution, stirred evenly, then sodium borohydride is added, stirred evenly, then sodium alginate and polyvinyl alcohol are added, stirred evenly at 65-85° C., ultrasonically treated, and dried to obtain the modified red clay loaded with iron.

2. The slow-release phosphorus removal material according to claim 1, characterized in that: The binder comprises silicate cement, polyacrylic acid and hydroxypropyl methylcellulose ether in a mass ratio of 1: (0.4-0.8): (0.2-0.6).

3. The slow-release phosphorus removal material according to claim 1, characterized in that: The particle size of the red clay is 200-600 meshes.

4. The slow-release phosphorus removal material according to claim 1, characterized in that: The mass ratio of the red clay, zinc oxide, rubidium hydroxide, sodium dodecylbenzene sulfonate and sulfuric acid solution is 1: (0.2-0.4): (0.1-0.3): (0.05-0.2): (4-20).

5. The slow-release phosphorus removal material according to claim 1, characterized in that: The mass ratio of the pretreated red soil, ferrous sulfate solution, sodium borohydride, sodium alginate and polyvinyl alcohol is 1: (4-20): (0.1-0.3): (0.05-0.2): (0.05-0.2).

6. The slow-release phosphorus removal material according to claim 1, characterized in that: The concentration of the sulfuric acid solution is 0.1-2 mol / L; the concentration of the ferrous sulfate solution is 0.1-2 mol / L.

7. The slow-release phosphorus removal material according to claim 1, characterized in that: The calcined oyster shell powder is obtained by calcining oyster shell powder at 350-420° C. and 650-720° C. in sequence.

8. The slow-release phosphorus removal material according to claim 7, characterized in that: The preparation method of the calcined oyster shell powder comprises the following steps: calcining the oyster shell powder at 350-420° C. for 40-80 min, and then calcining at 650-720° C. for 40-80 min to obtain the calcined oyster shell powder.

9. The slow-release phosphorus removal material according to claim 1, characterized in that: The compressive strength of the silicate cement is ≥32.5MPa.

10. The slow-release phosphorus removal material according to claim 1, characterized in that: The particle size of the calcium peroxide is 80-200 mesh; the particle size of the bentonite is 80-200 mesh.

11. The method for preparing the sustained-release phosphorus removal material according to any one of claims 1 to 10, characterized in that: The following steps are involved: Calcium peroxide, a binder, bentonite, calcined oyster shell powder and iron-loaded modified red clay are uniformly mixed to obtain a mixture, the mixture is added to a granulator, sprayed with water for granulation, particles with a particle size of 2 to 8 mm are sieved out, and the particles are dried or cured to obtain a slow-release phosphorus removal material.

12. The method for preparing a slow-release phosphorus removal material according to claim 11, characterized in that: The amount of atomized water added is 5-8wt% of the mixture.

13. Use of the slow-release phosphorus removal material according to any one of claims 1 to 10 in wastewater phosphorus removal treatment.

Images