Polymeric aluminum chloride sulfate and preparation method thereof

Abstract

The invention discloses polymeric aluminum sulfate and a preparation method thereof, and relates to the technical field of water treatment agents, and the preparation method specifically comprises the following steps: S1, preparing an aluminum chloride solution; the preparation method comprises the following steps: activating palygorskite, modifying the palygorskite by using gamma-methacryloxypropyltrimethoxysilane, and carrying out in-situ copolymerization on the surface of the palygorskite by using a polyacrylamide raw material to obtain modified palygorskite; s2, adding aluminum sulfate into an aluminum chloride solution, uniformly mixing, adding calcium oxide and water, adjusting the molar concentration of chloride ions and sulfate radicals, stirring and reacting at normal pressure, adding the modified palygorskite and an activating agent, and continuously stirring to obtain a reaction product; and S3, carrying out filter pressing, drying and packaging on the reaction product to obtain the polymeric aluminum sulfate. In the application, the modified palygorskite is introduced to provide a reaction base point for the formation of the polymeric aluminum sulfate; meanwhile, the flocculation performance of the polymeric aluminum sulfate during water treatment is synergistically enhanced with the activating agent in a specific proportion, and the water quality purification efficiency and effect are improved.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment agents, in particular to polyaluminium chloride sulfate and a preparation method thereof. Background Art

[0002] Water pollution is one of the major environmental problems facing the world today, mainly from industrial wastewater, domestic sewage, agricultural drainage, etc. These pollution sources contain a large number of organic matter, inorganic matter, heavy metals, microorganisms and other pollutants, which seriously threaten human health and ecological environment safety. Therefore, the development of efficient and environmentally friendly water treatment agents is of great significance to solving the problem of water pollution.

[0003] At present, commonly used water treatment agents mainly include polyaluminium chloride (PAC), polyaluminium sulfate, polyferrous sulfate, polyacrylamide, etc. These water treatment agents play the role of coagulation, sedimentation, filtration, etc. in the water treatment process, which helps to remove suspended matter, organic matter, heavy metals and other pollutants in the water. However, these traditional water treatment agents still have many shortcomings, such as slow sedimentation rate, small floccules, and poor treatment effect on high turbidity water.

[0004] Polyaluminium chloride sulfate (PACS) is a new type of high-efficiency water purifier. Compared with traditional polyaluminium chloride, it can function without adding alkaline additives or other coagulants and requires a smaller dosage. However, the current technology maturity is low and there are few practical applications. The flocculation effect of the prepared polyaluminium chloride sulfate cannot meet market demand.

[0005] In summary, in order to solve the above problems, it is of great significance to prepare a polyaluminum sulfate chloride with good flocculation effect. Summary of the invention

[0006] The object of the present invention is to provide a polyaluminium chloride sulfate and a preparation method thereof, so as to solve the problems raised in the prior art.

[0007] To achieve the above object, the present invention provides the following technical solutions: A method for preparing polyaluminium chloride sulfate comprises the following steps: S1: (1) adding aluminum hydroxide and hydrochloric acid to water and stirring evenly, stirring and reacting in a reactor to obtain an aluminum chloride solution; (2) activating palygorskite and modifying it with γ-methacryloxypropyltrimethoxysilane, and then in-situ copolymerizing the surface of the palygorskite with a polyacrylamide raw material to obtain modified palygorskite; S2: adding aluminum sulfate to aluminum chloride solution and mixing evenly, adding calcium oxide and water, adjusting the molar concentration ratio of chloride ion and sulfate ion with sodium chloride, stirring and reacting at normal pressure, adding modified palygorskite and activator and continuing stirring to obtain a reaction product; S3: The reaction product is filtered, dried and packaged to obtain polyaluminium sulfate chloride.

[0008] The aluminum chloride solution comprises the following raw materials, calculated by mass: 10-12 parts of aluminum hydroxide, 19-21 parts of hydrochloric acid, and 4-6 parts of water; the polyaluminum chloride comprises the following raw materials, calculated by mass: 3-5 parts of aluminum sulfate, 13-15 parts of aluminum chloride solution, 0.5-1 part of calcium oxide, 10-12 parts of water, 1-2 parts of auxiliary agent, and 1-3 parts of activator.

[0009] Among them, the concentration of hydrochloric acid is 30%.

[0010] Preferably, during the adjustment process, the molar concentration ratio of chloride ion to sulfate ion is 1:0.23-0.26.

[0011] Preferably, in step S1, during the stirring reaction in the reactor, the reaction pressure is 0.3-0.4 MPa, the reaction temperature is 130-150°C, and the time is 3-4 h; in step S2, during the stirring reaction at normal pressure, the temperature is 80-90°C, and the time is 30-40 min; during the continued stirring, the stirring temperature is 90-95°C, and the time is 3-4 h.

[0012] Preferably, the auxiliary agent includes modified palygorskite.

[0013] Preferably, the method for preparing the modified palygorskite comprises the following steps: (1) Add palygorskite to 4.5-5.5% sulfuric acid solution with a solid-liquid mass ratio of 1:12-20, stir at 80-90°C for 1.5-2h, wash with deionized water, filter and dry; transfer to a heating furnace, heat at 300-320°C for 4-4.5h under a nitrogen atmosphere, cool with the furnace, and crush to 700-800 mesh to obtain activated palygorskite; (2) adding activated palygorskite to deionized water and dispersing the mixture uniformly, adding γ-methacryloxypropyltrimethoxysilane and anhydrous ethanol, stirring the mixture at 50-55° C. for 3-4 hours, filtering, washing, and drying the mixture to obtain olefinic palygorskite; (3) 4-Aminomethyl-1,6-heptadien-4-ol, acrylamide and allyltrimethylammonium chloride are used as raw materials for polyacrylamide; alkenyl palygorskite is added to anhydrous ethanol and ultrasonically dispersed uniformly, polyacrylamide raw materials and azobisisobutyronitrile are added, stirred at 70-80°C for 3-5h, filtered, washed and dried to obtain modified palygorskite.

[0014] The alkenyl palygorskite comprises the following raw materials in parts by mass: 8 to 10 parts of activated palygorskite, 2 to 3 parts of γ-methacryloxypropyltrimethoxysilane, 70 to 85 parts of deionized water, and 10 to 15 parts of anhydrous ethanol; the modified palygorskite comprises the following raw materials in parts by mass: 10 to 12 parts of alkenyl palygorskite, 1 to 2 parts of 4-aminomethyl-1,6-heptadien-4-ol, 0.1 to 0.2 parts of azobisisobutyronitrile, 8 to 10 parts of acrylamide, 1.5 to 2.5 parts of allyltrimethylammonium chloride, and 60 to 70 parts of anhydrous ethanol.

[0015] Preferably, the activator comprises the following raw materials, in parts by mass: 20-22 parts of modified calcium aluminate, 3-5 parts of aluminum isopropoxide, 2-3 parts of sodium dodecylbenzene sulfonate, and 0.5-1 part of citric acid.

[0016] Preferably, the preparation method of the modified calcium aluminate comprises the following steps: adding silicon dioxide, aluminum hydroxide and calcium oxide to water and stirring evenly, stirring at 135-145°C for 5-6 hours under a pressure of 0.3-0.4 MPa, then adding glucose, stirring and reacting at 60-70°C for 8-9 hours at a stirring speed of 500-550 r / min under normal pressure, filtering, washing and drying to obtain modified calcium aluminate.

[0017] Wherein, the mass ratio of silicon dioxide, aluminum hydroxide, calcium oxide and glucose is 1.5:80~100:100~120:4~6.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention introduces palygorskite during the synthesis process. Palygorskite is a natural non-metallic clay mineral with a unique layered chain structure. It forms a small and numerous microporous structure after acid etching, and then undergoes high-temperature roasting to enlarge the micropores, thereby increasing the surface area. When added to the polyaluminum chloride sulfate synthesis process, on the one hand, the palygorskite structure can provide a reaction base for the synthesis. On the other hand, in the water treatment process, palygorskite can be used as a carrier of a coagulant to promote the collision, adsorption and bridging of the coagulant with suspended particles, colloidal substances, etc. in the water, thereby forming a larger floc, accelerating the sedimentation process, and improving the water purification efficiency.

[0019] The invention also modifies the palygorskite. After surface activation, vinyl groups are introduced by using a silane coupling agent, and copolymerization is performed with 4-aminomethyl-1,6-heptadien-4-ol and acrylamide, so that a large number of hydroxyl groups and amino groups are provided on the surface of the palygorskite, the synthesis efficiency of synthesizing polyaluminium chloride sulfate can be increased, and the adsorption effect on organic matter and metal ions can be improved during use. Meanwhile, 4-aminomethyl-1,6-heptadien-4-ol and acrylamide are combined by copolymerization to form a long-chain structure, which can play the role of a dispersant, prevent palygorskite particles from agglomerating during the coagulation process, help to increase the volume of flocs, and facilitate sedimentation. In addition, allyl trimethyl ammonium chloride is introduced during the copolymerization process, wherein the ammonium chloride can make the molecular chain carry ionizable positively charged groups, and by providing positive charges, it has a strong amplifying effect on the adsorption performance of negatively charged colloids, polymers and solid surfaces, enhances the adsorption bridging and electrical neutralization capabilities, and thus improves the flocculation effect.

[0020] (2) The present invention introduces an activator containing calcium aluminate during the synthesis process. The introduction of calcium aluminate can increase the basicity of polyaluminium sulfate chloride and can also adjust the pH value of the solution to a certain extent. The present invention modifies calcium aluminate during synthesis. The addition of silicon dioxide helps to improve the wettability of the material, improve the dispersion performance, and can be used as a catalyst to increase the reaction efficiency. After the addition of glucose, it helps to refine the modified calcium aluminate crystals. Adding it to the synthesis process of polyaluminium sulfate chloride helps to further improve the synthesis efficiency. In addition, the added activator also contains substances such as aluminum isopropoxide and sodium dodecylbenzene sulfonate, which can improve the dispersion of the material in the reactor, improve the reaction efficiency, and increase the flocculation performance of polyaluminium sulfate chloride. DETAILED DESCRIPTION

[0021] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0022] It should be noted that there are no special restrictions on the purchase manufacturers of all raw materials involved in the present invention, which exemplarily include: palygorskite, purity 99%, provided by Hubei Yongkuo Technology Co., Ltd.; γ-methacryloxypropyltrimethoxysilane, purity 99%, provided by Hubei Shishun Biotechnology Co., Ltd.; 4-aminomethyl-1,6-heptadien-4-ol, cas: 44866-40-2; acrylamide, purity 99%, provided by Jinjinle (Hunan) Chemical Co., Ltd.; allyltrimethylammonium chloride, purity 99%, provided by Hubei Qifei Pharmaceutical Chemical Co., Ltd.; silicon dioxide, cas: 14808-60-7, purity 99%, provided by Fuchen (Tianjin) Chemical Reagent Co., Ltd.; aluminum isopropoxide, purity 99%, provided by Yangzhou Zhongtianli New Materials Co., Ltd.; sodium dodecylbenzene sulfonate, purity 99%, provided by Jinan Shanhai Chemical Technology Co., Ltd.

[0023] In the following examples, parts are by mass, and raw materials are all commercially available.

[0024] Embodiment 1: A method for preparing polyaluminium sulfate chloride comprises the following steps: Step 1: Preparation of modified palygorskite: (1) Add 5% sulfuric acid solution to palygorskite at a mass ratio of 1:15, stir at 85°C for 1.5h, wash with deionized water, filter and dry, transfer to a heating furnace, heat at 310°C for 4h under a nitrogen atmosphere, cool with the furnace, and crush to 800 mesh to obtain activated palygorskite; (2) 9 parts of activated palygorskite were added to 80 parts of deionized water and dispersed evenly, 2.5 parts of γ-methacryloxypropyltrimethoxysilane and 13 parts of ethanol were added, stirred at 50° C. for 3.5 hours, filtered, washed, and dried to obtain olefinated palygorskite; (3) adding 11 parts of olefinated palygorskite to 65 parts of anhydrous ethanol and dispersing the mixture uniformly, adding 1.5 parts of 4-aminomethyl-1,6-heptadien-4-ol, 9 parts of acrylamide, 2 parts of allyltrimethylammonium chloride, and 0.2 parts of azobisisobutyronitrile, stirring the mixture at 75°C for 4 hours, filtering, washing, and drying the mixture to obtain modified palygorskite; Step 2: Preparation method of modified calcium aluminate: Add silicon dioxide, calcium oxide and aluminum hydroxide in a mass ratio of 1.5:90:110 into water and stir evenly, stir at 140°C for 5.5 hours at 0.3Mpa, then add glucose in a mass ratio of 1.5:5 to silicon dioxide, stir at 65°C for 8.5 hours at a stirring speed of 525r / min under normal pressure, filter, wash and dry to obtain modified calcium aluminate; Step 3: Preparation of polyaluminium chloride sulfate: S1: Add 11 parts of aluminum hydroxide and 20 parts of hydrochloric acid to 5 parts of water and stir evenly, and stir in a reactor at 0.35 MPa and 140°C for 3 hours to obtain an aluminum chloride solution; S2: 4 parts of aluminum sulfate were added to 14 parts of aluminum chloride solution and mixed evenly, 0.5 parts of calcium oxide and 11 parts of water were added, the molar concentration ratio of chloride ion and sulfate ion was adjusted to 1:0.25 with sodium chloride, and the reaction was stirred at 85°C and normal pressure for 35 minutes, 1.5 parts of modified palygorskite and 2 parts of activator were added, and the stirring was continued at 90°C for 3.5 hours to obtain a reaction product; S3: The reaction product is filtered, dried and packaged to obtain polyaluminium sulfate chloride.

[0025] The activator comprises the following raw materials in parts by mass: 21 parts of modified calcium aluminate, 4 parts of aluminum isopropoxide, 2.5 parts of sodium dodecylbenzene sulfonate, and 0.5 parts of citric acid.

[0026] Embodiment 2: A method for preparing polyaluminium sulfate chloride comprises the following steps: Step 1: Preparation of modified palygorskite: (1) Add 5% sulfuric acid solution to palygorskite at a mass ratio of 1:15, stir at 80°C for 1.5h, wash with deionized water, filter and dry, transfer to a heating furnace, heat at 300°C for 4h under a nitrogen atmosphere, cool with the furnace, and crush to 800 mesh to obtain activated palygorskite; (2) 8 parts of activated palygorskite were added to 70 parts of deionized water and dispersed evenly, 2 parts of γ-methacryloxypropyltrimethoxysilane and 10 parts of ethanol were added, stirred at 50° C. for 3 h, filtered, washed, and dried to obtain olefinated palygorskite; (3) adding 10 parts of olefinated palygorskite to 60 parts of anhydrous ethanol and dispersing the mixture uniformly, adding 1 part of 4-aminomethyl-1,6-heptadien-4-ol, 8 parts of acrylamide, 1.5 parts of allyltrimethylammonium chloride, and 0.1 parts of azobisisobutyronitrile, stirring the mixture at 70°C for 3 hours, filtering, washing, and drying the mixture to obtain modified palygorskite; Step 2: Preparation method of modified calcium aluminate: Add silicon dioxide, calcium oxide and aluminum hydroxide in a mass ratio of 1.5:80:100 into water and stir evenly, stir at 135°C for 5 hours at 0.3Mpa, then add glucose in a mass ratio of 1.5:4 to silicon dioxide, stir at 60°C for 8 hours at a stirring speed of 500r / min under normal pressure, filter, wash and dry to obtain modified calcium aluminate; Step 3: Preparation of polyaluminium chloride sulfate: S1: Add 10 parts of aluminum hydroxide and 19 parts of hydrochloric acid to 4 parts of water and stir evenly, and stir in a reactor at 0.3 MPa and 130°C for 3 hours to obtain an aluminum chloride solution; S2: Add 3 parts of aluminum sulfate to 13 parts of aluminum chloride solution and mix evenly, add 0.5 parts of calcium oxide and 10 parts of water, adjust the molar concentration ratio of chloride ion and sulfate ion to 1:0.23 with sodium chloride, stir and react at 80°C and normal pressure for 30 minutes, add 1 part of modified palygorskite and 1 part of activator, continue stirring at 90°C for 3 hours, and obtain a reaction product; S3: The reaction product is filtered, dried and packaged to obtain polyaluminium sulfate chloride.

[0027] The activator comprises the following raw materials in parts by mass: 20 parts of modified calcium aluminate, 3 parts of aluminum isopropoxide, 2 parts of sodium dodecylbenzene sulfonate, and 0.5 parts of citric acid.

[0028] Embodiment 3: A method for preparing polyaluminium sulfate chloride comprises the following steps: Step 1: Preparation of modified palygorskite: (1) Add 5% sulfuric acid solution to palygorskite at a mass ratio of 1:15, stir at 90°C for 2 h, wash with deionized water, filter and dry, transfer to a heating furnace, heat at 320°C for 4.5 h under a nitrogen atmosphere, cool with the furnace, and crush to 800 mesh to obtain activated palygorskite; (2) 10 parts of activated palygorskite were added to 85 parts of deionized water and dispersed evenly, 3 parts of γ-methacryloxypropyltrimethoxysilane and 15 parts of ethanol were added, stirred at 55° C. for 4 hours, filtered, washed, and dried to obtain olefinated palygorskite; (3) adding 12 parts of olefinated palygorskite to 70 parts of anhydrous ethanol and dispersing the mixture uniformly, adding 2 parts of 4-aminomethyl-1,6-heptadien-4-ol, 10 parts of acrylamide, 2.5 parts of allyltrimethylammonium chloride, and 0.2 parts of azobisisobutyronitrile, stirring the mixture at 80°C for 5 hours, filtering, washing, and drying the mixture to obtain modified palygorskite; Step 2: Preparation method of modified calcium aluminate: Add silicon dioxide, calcium oxide and aluminum hydroxide in a mass ratio of 1.5:100:120 into water and stir evenly, stir at 145°C for 6 hours at 0.4 MPa, then add glucose in a mass ratio of 1.5:6 to silicon dioxide, stir at 70°C for 9 hours at a stirring speed of 550 r / min under normal pressure, filter, wash and dry to obtain modified calcium aluminate; Step 3: Preparation of polyaluminium chloride sulfate: S1: Add 12 parts of aluminum hydroxide and 21 parts of hydrochloric acid to 6 parts of water and stir evenly, and stir in a reactor at 0.4 MPa and 150°C for 4 hours to obtain an aluminum chloride solution; S2: Add 5 parts of aluminum sulfate to 15 parts of aluminum chloride solution and mix evenly, add 1 part of calcium oxide and 12 parts of water, adjust the molar concentration ratio of chloride ion and sulfate ion to 1:0.26 with sodium chloride, stir and react at 90°C and normal pressure for 40 minutes, add 2 parts of modified palygorskite and 3 parts of activator, continue stirring at 95°C for 4 hours, and obtain a reaction product; S3: The reaction product is filtered, dried and packaged to obtain polyaluminium sulfate chloride.

[0029] The activator comprises the following raw materials in parts by mass: 22 parts of modified calcium aluminate, 5 parts of aluminum isopropoxide, 3 parts of sodium dodecylbenzene sulfonate, and 1 part of citric acid.

[0030] Comparative Example 1: Based on Example 1, polyacrylamide was introduced into palygorskite, and the other processes remained unchanged, as follows: Step 1: Preparation of modified palygorskite: (1) Add 5% sulfuric acid solution to palygorskite at a mass ratio of 1:15, stir at 85°C for 1.5h, wash with deionized water, filter and dry, transfer to a heating furnace, heat at 310°C for 4h under a nitrogen atmosphere, cool with the furnace, and crush to 800 mesh to obtain activated palygorskite; (2) 9 parts of activated palygorskite are added to 80 parts of deionized water and dispersed evenly, 12.5 parts of polyacrylamide with a molecular weight of 1000-2000 are added, stirred at 75°C for 3-4 hours, filtered, washed, and dried to obtain modified palygorskite; Step 2: Preparation method of modified calcium aluminate: Add silicon dioxide, calcium oxide and aluminum hydroxide in a mass ratio of 1.5:90:110 into water and stir evenly, stir at 140°C for 5.5 hours at 0.3Mpa, then add glucose in a mass ratio of 1.5:5 to silicon dioxide, stir at 65°C for 8.5 hours at a stirring speed of 525r / min under normal pressure, filter, wash and dry to obtain modified calcium aluminate; Step 3: Preparation of polyaluminium chloride sulfate: S1: Add 11 parts of aluminum hydroxide and 20 parts of hydrochloric acid to 5 parts of water and stir evenly, and stir in a reactor at 0.35 MPa and 140°C for 3 hours to obtain an aluminum chloride solution; S2: 4 parts of aluminum sulfate were added to 14 parts of aluminum chloride solution and mixed evenly, 0.5 parts of calcium oxide and 11 parts of water were added, the molar concentration ratio of chloride ion and sulfate ion was adjusted to 1:0.25 with sodium chloride, and the mixture was stirred at 85°C and normal pressure for 35 minutes, 1.5 parts of modified palygorskite and 2 parts of activator (21 parts of modified calcium aluminate, 4 parts of aluminum isopropoxide, 2.5 parts of sodium dodecylbenzene sulfonate, 0.5 parts of citric acid) were added, and stirring was continued at 90°C for 3.5 hours to obtain a reaction product; S3: The reaction product is filtered, dried and packaged to obtain polyaluminium sulfate chloride.

[0031] The activator comprises the following raw materials in parts by mass: 21 parts of modified calcium aluminate, 4 parts of aluminum isopropoxide, 2.5 parts of sodium dodecylbenzene sulfonate, and 0.5 parts of citric acid.

[0032] Comparative Example 2: Based on Example 1, the palygorskite was directly modified without activation, and the other processes remained unchanged, as follows: Step 1: Preparation of modified palygorskite: (1) crushing palygorskite to 800 meshes to obtain activated palygorskite; (2) 9 parts of activated palygorskite were added to 80 parts of deionized water and dispersed evenly, 2.5 parts of γ-methacryloxypropyltrimethoxysilane and 13 parts of ethanol were added, stirred at 50° C. for 3.5 hours, filtered, washed, and dried to obtain olefinated palygorskite; (3) adding 11 parts of olefinated palygorskite to 65 parts of anhydrous ethanol and dispersing the mixture uniformly, adding 1.5 parts of 4-aminomethyl-1,6-heptadien-4-ol, 9 parts of acrylamide, 2 parts of allyltrimethylammonium chloride, and 0.2 parts of azobisisobutyronitrile, stirring the mixture at 75°C for 4 hours, filtering, washing, and drying the mixture to obtain modified palygorskite; Step 2: Preparation method of modified calcium aluminate: Add silicon dioxide, calcium oxide and aluminum hydroxide in a mass ratio of 1.5:90:110 into water and stir evenly, stir at 140°C for 5.5 hours at 0.3Mpa, then add glucose in a mass ratio of 1.5:5 to silicon dioxide, stir at 65°C for 8.5 hours at a stirring speed of 525r / min under normal pressure, filter, wash and dry to obtain modified calcium aluminate; Step 3: Preparation of polyaluminium chloride sulfate: S1: Add 11 parts of aluminum hydroxide and 20 parts of hydrochloric acid to 5 parts of water and stir evenly, and stir in a reactor at 0.35 MPa and 140°C for 3 hours to obtain an aluminum chloride solution; S2: 4 parts of aluminum sulfate were added to 14 parts of aluminum chloride solution and mixed evenly, 0.5 parts of calcium oxide and 11 parts of water were added, the molar concentration ratio of chloride ion and sulfate ion was adjusted to 1:0.25 with sodium chloride, and the reaction was stirred at 85°C and normal pressure for 35 minutes, 1.5 parts of modified palygorskite and 2 parts of activator were added, and the stirring was continued at 90°C for 3.5 hours to obtain a reaction product; S3: The reaction product is filtered, dried and packaged to obtain polyaluminium sulfate chloride.

[0033] The activator comprises the following raw materials in parts by mass: 21 parts of modified calcium aluminate, 4 parts of aluminum isopropoxide, 2.5 parts of sodium dodecylbenzene sulfonate, and 0.5 parts of citric acid.

[0034] Comparative Example 3: Based on Example 1, no activator is added, and the other processes remain unchanged, as follows: Step 1: Preparation of modified palygorskite: (1) Add 5% sulfuric acid solution to palygorskite at a mass ratio of 1:15, stir at 85°C for 1.5h, wash with deionized water, filter and dry, transfer to a heating furnace, heat at 310°C for 4h under a nitrogen atmosphere, cool with the furnace, and crush to 800 mesh to obtain activated palygorskite; (2) 9 parts of activated palygorskite were added to 80 parts of deionized water and dispersed evenly, 2.5 parts of γ-methacryloxypropyltrimethoxysilane and 13 parts of ethanol were added, stirred at 50° C. for 3.5 hours, filtered, washed, and dried to obtain olefinated palygorskite; (3) adding 11 parts of olefinated palygorskite to 65 parts of anhydrous ethanol and dispersing the mixture uniformly, adding 1.5 parts of 4-aminomethyl-1,6-heptadien-4-ol, 9 parts of acrylamide, 2 parts of allyltrimethylammonium chloride, and 0.2 parts of azobisisobutyronitrile, stirring the mixture at 75°C for 4 hours, filtering, washing, and drying the mixture to obtain modified palygorskite; Step 2: Preparation of polyaluminium chloride sulfate: S1: Add 11 parts of aluminum hydroxide and 20 parts of hydrochloric acid to 5 parts of water and stir evenly, and stir in a reactor at 0.35 MPa and 140°C for 3 hours to obtain an aluminum chloride solution; S2: 4 parts of aluminum sulfate were added to 14 parts of aluminum chloride solution and mixed evenly, 0.5 parts of calcium oxide and 11 parts of water were added, the molar concentration ratio of chloride ion and sulfate ion was adjusted to 1:0.25 with sodium chloride, the reaction was stirred at 85°C and normal pressure for 35 minutes, 1.5 parts of modified palygorskite was added, and the stirring was continued at 90°C for 3.5 hours to obtain a reaction product; S3: The reaction product is filtered, dried and packaged to obtain polyaluminium sulfate chloride.

[0035] Comparative Example 4: Based on Example 1, the modified calcium aluminate was replaced with ordinary calcium aluminate, and the other processes remained unchanged, as follows: Step 1: Preparation of modified palygorskite: (1) Add 5% sulfuric acid solution to palygorskite at a mass ratio of 1:15, stir at 85°C for 1.5h, wash with deionized water, filter and dry, transfer to a heating furnace, heat at 310°C for 4h under a nitrogen atmosphere, cool with the furnace, and crush to 800 mesh to obtain activated palygorskite; (2) 9 parts of activated palygorskite were added to 80 parts of deionized water and dispersed evenly, 2.5 parts of γ-methacryloxypropyltrimethoxysilane and 13 parts of ethanol were added, stirred at 50° C. for 3.5 hours, filtered, washed, and dried to obtain olefinated palygorskite; (3) adding 11 parts of olefinated palygorskite to 65 parts of anhydrous ethanol and dispersing the mixture uniformly, adding 1.5 parts of 4-aminomethyl-1,6-heptadien-4-ol, 9 parts of acrylamide, 2 parts of allyltrimethylammonium chloride, and 0.2 parts of azobisisobutyronitrile, stirring the mixture at 75°C for 4 hours, filtering, washing, and drying the mixture to obtain modified palygorskite; Step 2: Preparation of polyaluminium chloride sulfate: S1: Add 11 parts of aluminum hydroxide and 20 parts of hydrochloric acid to 5 parts of water and stir evenly, and stir in a reactor at 0.35 MPa and 140°C for 3 hours to obtain an aluminum chloride solution; S2: 4 parts of aluminum sulfate were added to 14 parts of aluminum chloride solution and mixed evenly, 0.5 parts of calcium oxide and 11 parts of water were added, the molar concentration ratio of chloride ion and sulfate ion was adjusted to 1:0.25 with sodium chloride, and the reaction was stirred at 85°C and normal pressure for 35 minutes, 1.5 parts of modified palygorskite and 2 parts of activator were added, and the stirring was continued at 90°C for 3.5 hours to obtain a reaction product; S3: The reaction product is filtered, dried and packaged to obtain polyaluminium sulfate chloride.

[0036] The activator comprises the following raw materials in parts by mass: 21 parts of calcium aluminate, 4 parts of aluminum isopropoxide, 2.5 parts of sodium dodecylbenzene sulfonate, and 0.5 parts of citric acid.

[0037] Performance test: (1) According to the HJ828-2017 chemical oxygen demand (COD) test method, the COD removal rate of each embodiment sample was tested. Under 25°C conditions, the fixed dosage was 2 g / L, the treated water volume was 30 L, the initial COD content in the water was 300 mg / L, and the mixture was stirred at 150 r / min for 1 min and allowed to stand for 15 min. A middle layer sample was taken to measure the COD removal rate; (2) Sewage with a turbidity of 180° was prepared using kaolin and tap water. The fixed dosage was 2 g / L, the treated water volume was 30 L, and the temperature was 25°C. After the dosage was added, the mixture was stirred at 100 r / min for 1 min and allowed to stand for 10 min. A middle layer sample was taken and the water turbidity a was read using a GDS-3 photoelectric turbidity analyzer. The removal rate was calculated according to the formula (180-a) / 180×100%, measured as sludge removal rate. The experimental data are shown in Table 1.

[0038] Table 1 Conclusion: In Comparative Example 1, the palygorskite is directly introduced with polyacrylamide, and the binding property with the palygorskite is general, and the active functional groups are less, the adsorption capacity is reduced, and the flocculation effect is not as good as that in Example 1; in Comparative Example 2, the palygorskite is directly modified without activation, and the surface micropores are less and the surface area is low, which cannot promote the synthesis of polyaluminum chlorosulfate, and the flocculation effect is reduced; in Comparative Example 3, no activator is added, the reaction efficiency is significantly reduced, and the flocculation effect is reduced; in Comparative Example 4, the modified calcium aluminate is replaced with ordinary calcium aluminate, which has low wettability, poor dispersion performance, and the crystal structure is not refined, the reaction efficiency of synthesizing polyaluminum chlorosulfate is reduced, and the flocculation effect is reduced.

[0039] In summary, the present invention successfully prepares a polyaluminum chlorosulfate by introducing modified palygorskite and an activator containing modified calcium aluminate in the process of preparing aluminum chlorosulfate, which has good COD removal effect and sludge removal effect.

[0040] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing polyaluminium sulfate chloride, characterized in that: The following steps are involved: S1: (1) adding aluminum hydroxide and hydrochloric acid to water and stirring evenly, stirring and reacting in a reactor to obtain an aluminum chloride solution; (2) activating palygorskite and modifying it with γ-methacryloxypropyltrimethoxysilane, and then in-situ copolymerizing the surface of the palygorskite with a polyacrylamide raw material to obtain modified palygorskite; S2: adding aluminum sulfate to aluminum chloride solution and mixing evenly, adding calcium oxide and water, adjusting the molar concentration ratio of chloride ion and sulfate ion with sodium chloride, stirring and reacting at normal pressure, adding modified palygorskite and activator and continuing stirring to obtain a reaction product; S3: The reaction product is filtered, dried and packaged to obtain polyaluminium sulfate chloride.

2. The method for preparing a polyaluminium chloride sulfate according to claim 1, wherein: The aluminum chloride solution comprises the following raw materials, by mass: 10-12 parts of aluminum hydroxide, 19-21 parts of hydrochloric acid, and 4-6 parts of water; The polyaluminium chloride comprises the following raw materials, calculated by mass: 3-5 parts of aluminium sulfate, 13-15 parts of aluminium chloride solution, 0.5-1 parts of calcium oxide, 10-12 parts of water, 1-2 parts of modified palygorskite and 1-3 parts of activator.

3. The method for preparing a polyaluminium chloride sulfate according to claim 1, wherein: In step S2, during the adjustment process, the molar concentration ratio of chloride ion to sulfate ion is 1:0.23-0.

26.

4. The method for preparing a polyaluminium sulfate chloride according to claim 1, wherein: In step S1, during the stirring reaction in the reactor, the reaction pressure is 0.3-0.4 MPa, the reaction temperature is 130-150° C., and the time is 3-4 h; during the stirring reaction at normal pressure, the temperature is 80-90° C., and the time is 30-40 min; during the continued stirring, the stirring temperature is 90-95° C., and the time is 3-4 h.

5. The method for preparing a polyaluminium chloride sulfate according to claim 1, wherein: The preparation method of the modified palygorskite comprises the following steps: (1) Add palygorskite to 4.5-5.5% sulfuric acid solution with a solid-liquid mass ratio of 1:12-20, stir at 80-90°C for 1.5-2h, wash with deionized water, filter and dry; transfer to a heating furnace, heat at 300-320°C for 4-4.5h under a nitrogen atmosphere, cool with the furnace, and crush to 700-800 mesh to obtain activated palygorskite; (2) adding activated palygorskite to deionized water and dispersing the mixture uniformly, adding γ-methacryloxypropyltrimethoxysilane and anhydrous ethanol, stirring the mixture at 50-55° C. for 3-4 hours, filtering, washing, and drying the mixture to obtain olefinic palygorskite; (3) 4-Aminomethyl-1,6-heptadien-4-ol, acrylamide and allyltrimethylammonium chloride are used as raw materials for polyacrylamide; alkenyl palygorskite is added to anhydrous ethanol and ultrasonically dispersed uniformly, polyacrylamide raw materials and azobisisobutyronitrile are added, stirred at 70-80°C for 3-5h, filtered, washed and dried to obtain modified palygorskite.

6. The method for preparing a polyaluminium chloride sulfate according to claim 5, wherein: The alkenyl palygorskite comprises the following raw materials in parts by weight: 8 to 10 parts of activated palygorskite, 2 to 3 parts of γ-methacryloxypropyltrimethoxysilane, 70 to 85 parts of deionized water, and 10 to 15 parts of anhydrous ethanol; The modified palygorskite comprises the following raw materials in parts by weight: 10 to 12 parts of alkenyl palygorskite, 1 to 2 parts of 4-aminomethyl-1,6-heptadien-4-ol, 0.1 to 0.2 parts of azobisisobutyronitrile, 8 to 10 parts of acrylamide, 1.5 to 2.5 parts of allyltrimethylammonium chloride, and 60 to 70 parts of anhydrous ethanol.

7. The method for preparing a polyaluminium chloride sulfate according to claim 1, wherein: The activator comprises the following raw materials, calculated by mass: 20-22 parts of modified calcium aluminate, 3-5 parts of aluminum isopropoxide, 2-3 parts of sodium dodecylbenzene sulfonate, and 0.5-1 part of citric acid.

8. The method for preparing a polyaluminium chloride sulfate according to claim 7, wherein: The preparation method of modified calcium aluminate comprises the following steps: adding silicon dioxide, aluminum hydroxide and calcium oxide into water and stirring evenly, stirring at 135-145° C. for 5-6 hours under a pressure of 0.3-0.4 MPa, then adding glucose, stirring at 60-70° C. for 8-9 hours under normal pressure at a stirring speed of 500-550 r / min, filtering, washing and drying to obtain modified calcium aluminate.

9. The method for preparing a polyaluminium chloride sulfate according to claim 8, wherein: The mass ratio of silicon dioxide, aluminum hydroxide, calcium oxide and glucose is 1.5:80-100:100-120:4-6.

10. The polyaluminium chloride sulfate prepared according to the method for preparing a polyaluminium chloride sulfate according to any one of claims 1 to 9.

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