Preparation method and application of zeolite ceramsite for advanced treatment of ammonia-nitrogen wastewater

Abstract

The invention discloses zeolite ceramsite for advanced treatment of ammonia-nitrogen wastewater and a preparation method and application thereof, and relates to the field of ammonia-nitrogen wastewater treatment.The preparation method comprises the steps that 1, acidified fly ash, phosphate tailings and montmorillonite are mixed, and then a pore forming agent is added to obtain premixed powder; (2) performing wet mixing to obtain high-dispersion premixed powder; (3) adding sodium metaaluminate and sodium hydroxide, mixing, crushing and grinding to obtain fully mixed powder; (4) carrying out compression molding to obtain a columnar raw material with the diameter of 5-8 mm and the length of 8-10 mm, drying, roasting, and naturally cooling to room temperature to obtain activated ceramsite; and (5) adding the activated ceramsite into deionized water for hydrothermal reaction, and cleaning and drying to obtain the zeolite ceramsite for advanced treatment of ammonia-nitrogen wastewater. The zeolite ceramsite disclosed by the invention has the characteristics of large specific surface area, developed pore structure and high compressive strength, has the advantages of high selectivity on NH4 < + > in ammonia-nitrogen wastewater, strong anti-interference ion capacity and the like, and still keeps a good effect after cyclic regeneration.

Description

Technical Field

[0001] The invention relates to the field of ammonia nitrogen wastewater treatment, and specifically refers to a zeolite ceramsite for deep treatment of ammonia nitrogen wastewater and a preparation method and application thereof. Background Art

[0002] Ammonia is an important raw material in the phosphorus chemical industry. Some chemical reactions in the production process will generate ammonia nitrogen as a by-product and be discharged from the wastewater. Ammonia nitrogen (free NH3 and ionized NH4 + ) is one of the common wastewater pollutants and an important monitoring indicator for industrial wastewater discharge in my country. Ammonia nitrogen in wastewater from the phosphorus chemical industry is different from ammonia nitrogen in domestic wastewater. It has the characteristics of high concentration, poor biodegradability, and many interfering ions. Improperly treated ammonia nitrogen wastewater has serious harm to the ecological environment and human body.

[0003] At present, the main methods for treating ammonia nitrogen wastewater are biological method, chemical method and physical and chemical method. The biological method has the advantages of large processing capacity, low cost and stable reaction, but it has high requirements for the biodegradability of wastewater, and microorganisms are sensitive to the environment, so the use of biological denitrification has limitations. The chemical method has the advantages of wide application range, fast reaction speed and high treatment effect, but there are shortcomings such as secondary pollution, expensive chemical agents and high cost, which limit the application of chemical method in treating ammonia nitrogen in wastewater. The physical and chemical method has the advantages of simple operation, low energy consumption, recyclability and environmental friendliness, and is widely used in the treatment of ammonia nitrogen wastewater.

[0004] The ammonia nitrogen concentration of wastewater discharged from the phosphorus chemical industry is generally around 200 mg / L, which is a medium-low concentration. It also contains Ca 2+ Mg 2+ , Fe 3+ 、SO4 2- PO4 3- In traditional treatment methods such as biological treatment, the ammonia nitrogen concentration in wastewater is too high, and the carbon-nitrogen ratio of wastewater is low, so additional carbon sources need to be added, which increases the cost of treatment. If chemical agents are added for treatment, the treatment cost will increase under ideal conditions without considering the generation of secondary pollutants, and it is difficult to treat the ammonia nitrogen concentration to below 30 mg / L at one time. If physical and chemical methods are used, zeolite is used as a typical representative for treatment, there will still be some limitations. On the one hand, the upper limit of the concentration that zeolite can treat is not high, and on the other hand, many interfering ions will react with NH4 + Competition for reaction sites results in very limited removal efficiency.

[0005] Therefore, there is an urgent need to develop a zeolite preparation method with high selectivity for ammonia nitrogen in wastewater and strong anti-interference ability, aiming to provide a deep treatment method for ammonia nitrogen wastewater in the phosphorus chemical industry. Summary of the invention

[0006] The purpose of the present invention is to solve the shortcomings of the above-mentioned background technology. With fly ash as the base material and phosphate tailings and montmorillonite as auxiliary agents, a method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater is provided, which has high selectivity for ammonia nitrogen in wastewater and strong anti-interference ability.

[0007] The technical solution of the present invention is: a method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, comprising the following steps:

[0008] A method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, characterized in that it comprises the following steps:

[0009] (1) mixing acidified fly ash, phosphorus tailings, and montmorillonite in a mass ratio of (5-10):(1-5):1, and then adding stearic acid as a pore-forming agent in a mass ratio of 1% to 5% of the total mass of the acidified fly ash, phosphorus tailings, and montmorillonite to obtain a premixed powder;

[0010] (2) using ethanol aqueous solution as a dispersant, placing the premixed powder obtained in step (1) in the dispersant, stirring in a constant temperature water bath at 60 to 75° C. for 1 to 4 hours, and then centrifuging and drying to obtain a highly dispersed premixed powder;

[0011] (3) adding sodium aluminate to the highly dispersed premixed powder obtained in step (2) to adjust the silicon-aluminum ratio to 1: (1-1.5), then adding solid sodium hydroxide, mixing and grinding thoroughly to less than 200 meshes, to obtain a fully mixed powder;

[0012] (4) pressing the fully mixed powder obtained in step (3) into a shape to obtain a columnar raw material with a diameter of 5 to 8 mm and a length of 8 to 10 mm, drying the raw material, calcining the raw material in a muffle furnace, and naturally cooling the raw material to room temperature to obtain activated ceramsite;

[0013] (5) Add the activated ceramsite obtained in step (4) into deionized water, and perform a hydrothermal reaction at 75 to 95° C. for 4 to 12 hours. After the reaction is completed, wash and dry to obtain zeolite ceramsite for deep treatment of ammonia nitrogen wastewater.

[0014] Preferably, in step (1), the acidified fly ash is prepared by a method comprising the following steps: placing fly ash in dilute hydrochloric acid with a mass concentration of 5% to 10%, the mass ratio of fly ash to dilute hydrochloric acid being 1:(10 to 20), stirring in a constant temperature water bath at 65 to 85°C for 2 to 4 hours, and then filtering, washing, and drying to obtain acidified fly ash. Fly ash usually contains a certain amount of iron substances, including Fe2O3 (or hematite, siderite, limonite, etc.) that is easily soluble in acid and magnetic iron compounds that are insoluble in acid, but iron is an inert agent for synthesizing zeolite, and at the same time causes the zeolite product to be light green or brick yellow. Hydrochloric acid is used to react with soluble iron and then enter the solution to achieve the purpose of partial iron removal.

[0015] Step (2) of the present invention adopts wet dispersion, stearic acid is melted into liquid phase at 60-65°C and dispersed in an aqueous solution of ethanol, and the pore-forming agent stearic acid is evenly dispersed in the solid powder by stirring. Compared with ordinary direct mixing, the pore-forming agent can be mixed more gently and evenly.

[0016] Preferably, in step (2), the volume fraction of the ethanol aqueous solution is 10% to 20%, and the mass ratio of the premixed powder to the dispersant is 1:(5 to 10).

[0017] Preferably, in step (3), the mass ratio of sodium hydroxide to acidified fly ash is 1: 1. Further, in step (3), the silicon-aluminum ratio n (Si / Al) = 1:1.

[0018] Preferably, in step (4), the drying is performed at 95-105°C for 1-2 hours, and the roasting comprises first heating the temperature to 400-500°C at a heating rate of 5-8°C / min, preheating for 30-60 minutes, and then heating the temperature to 550-750°C at a heating rate of 10-12°C / min and keeping the temperature for 1-4 hours.

[0019] Preferably, in step (5), the mass ratio of activated ceramsite to deionized water is 1:3 to 10.

[0020] Preferably, in step (5), the hydrothermal reaction is carried out at 75-85° C. for 6 h.

[0021] Preferably, in step (5), the cleaning and drying comprises: washing with deionized water until the pH of the washing solution is 7 to 10, and then drying at 95 to 105° C. for 1 to 2 hours.

[0022] The raw materials used in the present invention are as follows: the SiO2 content in the acidified fly ash is in the range of 60% to 70%, the Al2O3 content is in the range of 15% to 20%, and the remainder is MgO+CaO and impurities; the SiO2 content in the phosphate tailings is in the range of 4% to 10%, the Al2O3 content is in the range of 0.15% to 1.5%, and the remainder is MgO+CaO and impurities; the SiO2 content in the montmorillonite is in the range of 50% to 60%, the Al2O3 content is in the range of 20% to 25%, and the remainder is MgO+CaO and impurities (the above percentages are all weight percentages).

[0023] The SiO2 content in acidified fly ash, phosphate tailings and montmorillonite is higher than that in Al2O3, so sodium aluminate needs to be added to adjust the silicon-aluminum ratio n (Si / Al), that is, the molar ratio of elemental silicon to elemental aluminum in the raw materials.

[0024] The invention provides a zeolite ceramsite for deep treatment of ammonia nitrogen wastewater prepared according to the preparation method.

[0025] The present invention also provides an application of zeolite ceramsite for deep treatment of low-concentration ammonia nitrogen wastewater.

[0026] Preferably, the ammonia nitrogen concentration in the wastewater is 50 mg / L to 200 mg / L, and the dosage of zeolite ceramsite in the wastewater is 40 to 120 g / L.

[0027] The preparation principle of zeolite ceramsite of the present invention is:

[0028] As for raw materials, fly ash is used as the silicon-aluminum source skeleton material, phosphate tailings are used as flux, montmorillonite is used as a binder, and solid stearic acid is introduced as a pore-forming agent; sodium aluminate is used as an aluminum source supplement to adjust the silicon-aluminum ratio; sodium hydroxide is added as an alkali flux to promote the dissolution of the glass in the raw materials on the basis of high-temperature calcination, effectively destroy the crystal structure of inert substances (quartz and mullite), and at the same time decompose the silicon-aluminum active substances into aluminosilicate colloids required for the synthesis of zeolite, which significantly improves the overall activation level of the raw materials and provides an alkaline environment for subsequent hydrothermal treatment.

[0029] Step (4) high temperature calcination forms a ceramsite matrix. High temperature calcination can also destroy the crystalline structure of inert components such as mullite and quartz to release amorphous SiO2 and Al2O3, thereby significantly improving the activity of raw materials such as fly ash and phosphate tailings, thereby facilitating crystallization in the subsequent hydrothermal reaction.

[0030] The purpose of the hydrothermal reaction in step (5) is to crystallize zeolite. The zeolite ceramsite finally obtained has a good adsorption effect on the ammonium salt form of ammonia nitrogen in the ammonia nitrogen wastewater. The zeolite ceramsite has high physical strength and can be used repeatedly after regeneration to avoid secondary pollution.

[0031] The beneficial effects of the present invention are:

[0032] (1) The present invention provides a way to recycle solid waste resources. Industrial solid waste, such as fly ash and phosphate tailings, is used as the main substrate. Type A zeolite ceramsite is prepared by an alkali melting-hydrothermal method. The rich microporous structure gives it excellent adsorption performance. The cylindrical zeolite ceramsite has a strength of up to 12.3 MPa, a long service life, and is easy to recycle.

[0033] (2) The present invention uses calcium-magnesium-rich phosphate tailings as raw materials to replace part of the fly ash to prepare type A zeolite ceramsite. On the one hand, dolomite in the phosphate tailings will release a large amount of CO2 during the high-temperature calcination process to form a rich pore structure, so that the pore size range of the zeolite ceramsite is expanded from mesopore to micropore size; on the other hand, CaO and MgO generated during the high-temperature calcination process can act as flux to lower the melting point of the system and promote the reaction.

[0034] (3) The high temperature calcination of the present invention has a good promoting effect on the subsequent hydrothermal synthesis, specifically: during the high temperature calcination, CaO and MgO react with the sodium silicate in the raw material, promoting the Na+ Freed from its compounds; during hydrothermal synthesis, in addition to the Na contained in the raw material sodium hydroxide + , free Na + Ions can supplement it and work together with silicate (SiO4 4- ) and aluminate (AlO4 5- ) ions react to form zeolite crystals faster and more efficiently.

[0035] (4) The zeolite ceramsite provided by the present invention has a significant effect on NH 4+ Highly selective in Ca 2+ ,Mg 2+ , SO4 2- , HPO4 2- , H2PO4 - ,PO4 3- It shows strong anti-interference ability when there are interfering ions, mainly because of the large amount of Ca introduced by phosphate tailings. 2+ ,Mg 2+ Solidified on the surface of zeolite ceramsite, Ca 2+ ,Mg 2+ The pores formed by the escape of CO2 during the high-temperature calcination of phosphorus tailings are micropores, which have a great impact on SO4 2- , HPO4 2- , H2PO4 - ,PO4 3- Ionic groups of equal diameter have a shielding effect.

[0036] (4) The zeolite ceramsite provided by the present invention is suitable for the treatment of wastewater containing medium and low concentrations of ammonia nitrogen of 50 to 200 mg / L. After 8 hours of reaction, the ammonia nitrogen removal efficiency in the wastewater can reach more than 95%, the deep treatment effect is significant, and it can be recycled. The ammonia nitrogen removal rate of the zeolite ceramsite after desorption and regeneration still reaches more than 90%.

[0037] (5) The zeolite ceramsite preparation process of the present invention is simple and safe, and is suitable for industrial-scale production. Moreover, most of the raw materials of the present invention are solid wastes such as tailings, and the win-win goal of "using waste to treat waste" can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The N2 adsorption-desorption curve and pore size distribution diagram of ZC-01 prepared in Example 1;

[0039] Figure 2 X-ray diffraction analysis spectrum (XRD) of ZC-01 prepared in Example 1

[0040] Figure 3The scanning electron microscope (SEM) and energy dispersive spectrum (EDS) images of ZC-01 prepared in Example 1;

[0041] Figure 4 The treatment effects of ZC-01, ZC-02, ZC-03, ZC-04 prepared in Examples 1 to 4 and ZC-05 and ZC-06 prepared in Comparative Examples 1 to 2 on actual ammonia nitrogen wastewater under different pH conditions;

[0042] Figure 5 This is the treatment effect of ZC-01 used in Example 5 on ammonia nitrogen wastewater after desorption and regeneration;

[0043] Figure 6 The treatment effect of ZC-01 prepared in Example 1 on ammonia nitrogen wastewater containing interfering ions;

[0044] Figure 7 This is a physical picture of the preparation of ZC-01 in Example 1. DETAILED DESCRIPTION

[0045] The following specific examples further illustrate the present invention in detail. The drugs used in the examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods in the art unless otherwise specified. The amounts of raw materials used in Examples 1-4 are shown in Table 1 below.

[0046] Table 1 Raw material dosage (g)

[0047]

[0048] The acidified fly ash used in the following examples was prepared according to the following steps:

[0049] The fly ash was passed through a 200-mesh sieve, and the sieved fly ash was placed in dilute hydrochloric acid with a mass concentration of 5%, the mass ratio of fly ash to dilute hydrochloric acid being 1:20, and stirred in a constant temperature water bath at 65°C for 2 hours, and then separated by suction filtration, and the filter cake was washed with distilled water for multiple times until the pH value was close to 7, and then the filter cake was dried and ground to obtain acidified fly ash.

[0050] Example 1

[0051] This embodiment provides a method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, comprising the following steps:

[0052] (1) 21 g of acidified fly ash (containing SiO2 69.35% and Al2O3 17.52%), 6 g of phosphate tailings (containing SiO2 4.6% and Al2O3 0.25%), and 3 g of montmorillonite (containing SiO2 58.95% and Al2O3 20.06%) were mixed, and 1 g of stearic acid particles was added as a pore-forming agent to obtain a premixed powder.

[0053] (2) Using 20% ​​ethanol aqueous solution as a dispersant, the premixed powder is placed in the dispersion liquid at a mass ratio of premixed powder to dispersant of 1:10, stirred in a constant temperature water bath at 65°C for 1 hour, and then centrifuged and dried to obtain a highly dispersed premixed powder.

[0054] (3) 15.8 g of sodium aluminate was added to adjust the powder silicon-aluminum ratio n (Si / Al) to 1:1, and 21 g of sodium hydroxide solid was added, and the mixture was fully mixed and ground to less than 200 mesh to obtain a fully mixed powder.

[0055] (4) The whole mixed powder is pressed into shape by a mold to obtain cylindrical particles with a diameter of 5-8 mm and a length of 8-10 mm. The particles are dried in a drying oven at 105°C for 1 h and then placed in a muffle furnace. The mixture is first heated to 400°C at a heating rate of 8°C / min and preheated for 30 minutes. The mixture is then heated to 750°C at a heating rate of 10°C / min and kept at this temperature for 1 h. The particles are then naturally cooled to room temperature to obtain activated ceramsite.

[0056] (5) Add the activated ceramsite to deionized water in a mass ratio of 1:6, and perform hydrothermal reaction at 85°C for 6 hours. After the reaction is completed, take out the ceramsite and rinse it with deionized water until the pH value of the washing liquid is 8-10, and dry it in a drying oven at 105°C for 1 hour to obtain zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, which is denoted as ZC-01. The actual picture is as follows Figure 7 shown.

[0057] Example 2

[0058] This embodiment provides a method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, comprising the following steps:

[0059] (1) 24 g of acidified fly ash (containing SiO2 69.35% and Al2O3 17.52%), 3 g of phosphate tailings (containing SiO2 4.6% and Al2O3 0.25%), and 3 g of montmorillonite (containing SiO2 58.95% and Al2O3 20.06%) were mixed, and 1 g of stearic acid particles were added as a pore-forming agent to obtain a premixed powder.

[0060] (2) Using 20% ​​by volume ethanol aqueous solution as a dispersant, the premixed powder is placed in the dispersant at a mass ratio of premixed powder to dispersant of 1:10, stirred in a constant temperature water bath at 60° C. for 1 h, and then centrifuged, washed, and dried to obtain a highly dispersed premixed powder.

[0061] (3) 17.6 g of sodium aluminate was added to adjust the silicon-aluminum ratio n (Si / Al) to 1:1, and then 24 g of solid sodium hydroxide was added. The mixture was fully mixed and ground to less than 200 mesh to obtain a fully mixed powder.

[0062] (4) The whole mixed powder is pressed into shape by a mold to obtain cylindrical particles with a diameter of 5-8 mm and a length of 8-10 mm. The particles are dried in a drying oven at 105°C for 1 h and then placed in a muffle furnace. The mixture is first heated to 400°C at a heating rate of 8°C / min and preheated for 30 minutes. The mixture is then heated to 750°C at a heating rate of 10°C / min and calcined for 1 h. The particles are naturally cooled to room temperature to obtain activated ceramsite.

[0063] (3) Activated ceramsite was added into deionized water with a mass ratio of activated ceramsite to deionized water of 1:6, and subjected to hydrothermal reaction at 75°C for 6 hours. After the reaction was completed, the ceramsite was taken out and rinsed with deionized water until the pH value of the washing solution was 8-10, and dried in a drying oven at 105°C for 1 hour to obtain zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, which was recorded as ZC-02.

[0064] Example 3

[0065] This embodiment provides a method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, comprising the following steps:

[0066] (1) 21 g of acidified fly ash (containing SiO2 69.35% and Al2O3 17.52%), 14 g of phosphate tailings (containing SiO2 4.6% and Al2O3 0.25%), and 3 g of montmorillonite (containing SiO2 58.95% and Al2O3 20.06%) were mixed, and 1 g of stearic acid particles was added as a pore-forming agent to obtain a premixed powder.

[0067] (2) Using 10% by volume ethanol aqueous solution as a dispersant, the premixed powder is placed in the dispersant at a mass ratio of mixed powder to dispersant of 1:10, stirred in a constant temperature water bath at 65°C for 1 hour, and then centrifuged, washed, and dried to obtain a highly dispersed premixed powder.

[0068] (3) 16.3 g of sodium aluminate was added to adjust the silicon-aluminum ratio n (Si / Al) to 1:1, and then 21 g of solid sodium hydroxide was added. The mixture was thoroughly mixed and ground to less than 200 mesh to obtain a fully mixed powder.

[0069] (4) The whole mixed powder is pressed into shape by a mold to obtain cylindrical particles with a diameter of 5 to 8 mm and a length of 8 to 10 mm, dried in a drying oven at 105° C. for 1 h, and then placed in a muffle furnace for calcination. The mixture is first heated to 400° C. at a heating rate of 8° C. / min and preheated for 30 minutes, then heated to 750° C. at a heating rate of 10° C. / min and calcined for 1 h, and then naturally cooled to room temperature to obtain activated particles;

[0070] (5) The activated particles were added into deionized water, with the mass ratio of activated ceramsite to deionized water being 1:6, and subjected to hydrothermal reaction at 75°C for 6 h. After the reaction was completed, the particles were taken out and rinsed with deionized water until the pH of the washing solution was 8-10, and dried in a drying oven at 105°C for 1 h to obtain zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, which was recorded as ZC-03.

[0071] Example 4

[0072] This embodiment provides a method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, comprising the following steps:

[0073] (1) 21 g of acidified fly ash (containing 69.35% SiO2 and 17.52% Al2O3), 6 g of phosphate tailings (containing 4.6% SiO2 and 0.25% Al2O3), and 3 g of montmorillonite (containing 58.95% SiO2 and 20.06% Al2O3) were added with 1 g of stearic acid particles as a pore-forming agent to obtain a premixed powder.

[0074] (2) Using 10% ethanol aqueous solution as a dispersant, the premixed powder is placed in the dispersant at a mass ratio of 1:10, stirred in a constant temperature water bath at 60°C for 0.5h, and then centrifuged, washed, and dried to obtain a highly dispersed premixed powder.

[0075] (3) 16.0 g of sodium aluminate was added to adjust the silicon-aluminum ratio n (Si / Al) to 1:1, and then 21 g of solid sodium hydroxide was added. The mixture was fully mixed and ground to less than 200 mesh to obtain a fully mixed powder.

[0076] (4) The whole mixed powder is pressed into shape by a mold to obtain cylindrical particles with a diameter of 5 to 8 mm and a length of 8 to 10 mm, dried in a drying oven at 105° C. for 1 h, and then placed in a muffle furnace, first heated to 400° C. at a heating rate of 8° C. / min, preheated for 30 minutes, and then heated to 750° C. at a heating rate of 10° C. / min, and calcined for 1 h to obtain activated particles;

[0077] (5) Add the activated particles into deionized water, with the mass ratio of activated ceramsite to deionized water being 1:6, and subject to hydrothermal reaction at 75°C for 6 hours. After the reaction is completed, take out the particles, rinse them with deionized water, and dry them in a drying oven at 105°C for 1 hour to obtain zeolite ceramsite for deep treatment of ammonia nitrogen wastewater. This is denoted as ZC-04.

[0078] Comparative Example 1

[0079] This comparative example provides a method for preparing mesoporous ceramsite, comprising the following steps:

[0080] (1) 21 g of acidified fly ash (containing 69.35% SiO2 and 17.52% Al2O3), 3 g of phosphate tailings (containing 4.6% SiO2 and 0.25% Al2O3), and 3 g of montmorillonite (containing 58.95% SiO2 and 20.06% Al2O3) were mixed to obtain a premixed powder.

[0081] (2) Using 20% ​​ethanol aqueous solution as a dispersant, the premixed powder is placed in the dispersant at a mass ratio of premixed powder to dispersion liquid of 1:10, stirred in a constant temperature water bath at 60°C for 1 hour, and then centrifuged, washed, and dried to obtain a highly dispersed premixed powder.

[0082] (3) 15.8 g of sodium aluminate was added to adjust the silicon-aluminum ratio n (Si / Al) to 1:1, and then 21 g of solid sodium hydroxide was added. The mixture was fully mixed and ground to less than 200 mesh to obtain a fully mixed powder.

[0083] (4) The whole mixed powder is pressed into shape by a mold to obtain cylindrical particles with a diameter of 5-8 mm and a length of 8-10 mm. The particles are dried in a drying oven at 105°C for 1 h and then placed in a muffle furnace. The mixture is first heated to 400°C at a heating rate of 8°C / min and preheated for 30 minutes. The mixture is then heated to 750°C at a heating rate of 10°C / min and calcined for 1 h. The particles are naturally cooled to room temperature to obtain activated ceramsite.

[0084] (3) Activated ceramsite was added into deionized water with a mass ratio of activated ceramsite to deionized water being 1:6, and subjected to hydrothermal reaction at 75°C for 6 h. After the reaction was completed, the ceramsite was taken out and rinsed with deionized water, and dried in a drying oven at 105°C for 1 h to obtain zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, which was recorded as ZC-05.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing mesoporous ceramsite, comprising the following steps:

[0087] (1) 21 g of acidified fly ash (containing SiO2 69.35%, Al2O3 17.52%) and 3 g of montmorillonite (containing SiO2 58.95%, Al2O3 20.06%) were mixed, and 1 g of stearic acid particles were added as a pore-forming agent to obtain a premixed powder.

[0088] (2) Using 20% ​​by volume ethanol aqueous solution as a dispersant, the premixed powder is placed in the dispersant at a mass ratio of premixed powder to dispersant of 1:10, stirred in a constant temperature water bath at 60° C. for 1 h, and then centrifuged, washed, and dried to obtain a highly dispersed premixed powder.

[0089] (3) 15.4 g of sodium aluminate was added to adjust the silicon-aluminum ratio n (Si / Al) to 1:1, and then 21 g of solid sodium hydroxide was added. The mixture was thoroughly mixed and ground to less than 200 mesh to obtain a fully mixed powder.

[0090] (4) The whole mixed powder is pressed into shape by a mold to obtain cylindrical particles with a diameter of 5-8 mm and a length of 8-10 mm. The particles are dried in a drying oven at 105°C for 1 h and then placed in a muffle furnace. The mixture is first heated to 400°C at a heating rate of 8°C / min and preheated for 30 minutes. The mixture is then heated to 750°C at a heating rate of 10°C / min and calcined for 1 h. The particles are naturally cooled to room temperature to obtain activated ceramsite.

[0091] (3) Activated ceramsite was added into deionized water with a mass ratio of activated ceramsite to deionized water being 1:6, and subjected to hydrothermal reaction at 75°C for 6 h. After the reaction was completed, the ceramsite was taken out and rinsed with deionized water, and dried in a drying oven at 105°C for 1 h to obtain zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, which was recorded as ZC-06.

[0092] Example 5

[0093] Weigh 5g of each of ZC-01, ZC-02, ZC-03, ZC-04, ZC-05 and ZC-06 and treat 100ml of actual phosphorus chemical wastewater (containing interfering ions Ca 2+ Mg 2+ 、Al 3+ 、SO4 2- PO4 3- ), ammonia nitrogen concentration of 200 mg / L, treatment time of 8 hours, shaking intensity of 120 rpm, determination of ammonia nitrogen concentration in wastewater according to the reference standard "Determination of ammonia nitrogen in water quality - Nessler's reagent spectrophotometry" (HJ 5352009), the results are as follows Figure 4 As shown. Figure 4 It can be seen that the ammonia nitrogen removal rate of the zeolite ceramsite prepared in Examples 1 to 4 is significantly higher than that of the zeolite ceramsite prepared in Comparative Examples 1 to 2, among which the zeolite ceramsite prepared in Examples 1 to 4 has the best effect under neutral conditions (pH=7). When pH=7, after 8 hours of reaction, the ammonia nitrogen removal rate of the zeolite ceramsite prepared in Examples 1 to 4 reaches more than 95%; while the ammonia nitrogen removal rate of the zeolite ceramsite prepared in Comparative Examples 1 to 2 under the same conditions is only about 85%.

[0094] Example 6

[0095] The ZC-01 used in Example 5 was recovered and immersed in 100 ml of 1.5 mol / L NaCl solution for 2 h for desorption regeneration (Na in the solution was + With NH4 in ZC-01 + Ion exchange), dried and used again to treat actual wastewater with an ammonia nitrogen concentration of 200 mg / L at a pH of 7 for 8 hours with a shaking intensity of 120 rpm. Figure 5 As shown. Figure 5It can be seen that the ammonia nitrogen removal rate of ZC-01 after desorption and regeneration still reaches more than 90%.

[0096] Example 7

[0097] Weigh 5 g of ZC-01 prepared in Example 1 and add 5 g of ZC-01 to the mixture containing the interfering ion Ca 2+ ,Mg 2+ , Al 3+ The anti-interference ion test was carried out in the simulated ammonia nitrogen wastewater. The ammonia nitrogen concentration in the simulated wastewater was 100 mg / L, the simulated wastewater volume was 100 ml, and the Ca 2+ ,Mg 2+ , Al 3+ The concentrations were 0.1 mol / L, 0.2 mol / L, and 0.5 mol / L, respectively. The treatment time was 8 hours and the shaking intensity was 120 rpm. Figure 6 As shown. Figure 6 It can be seen that the interfering ions have little effect on the adsorption effect of ZC-01. When adding various interfering ions, the removal efficiency of ammonia nitrogen by ZC-01 still reaches more than 90%, which once again proves that ZC-01 zeolite ceramsite has strong anti-interference ability.

[0098] Performance Testing

[0099] (1) The chemical composition analysis (%) of ZC-01 prepared in Example 1 was performed using an X-ray fluorescence spectrometer (XRF). The results are shown in Table 2 below.

[0100] Table 2 Chemical composition analysis of ZC-01 (%)

[0101]

[0102] It can be seen from the data in Table 2 that the main components of ZC-01 are SiO2, Al2O3 and Na2O, and their chemical composition content is similar to that of standard Na-A zeolite.

[0103] (2) The pore structure parameters and compressive strength of ZC-01, ZC-02, ZC-03, ZC-04 prepared in Examples 1 to 4 and ZC-05 and ZC-06 prepared in Comparative Examples 1 to 2 were tested using a BET instrument.

[0104] Table 3 Pore structure parameters and compressive strength of ZC-01

[0105]

[0106] As can be seen from the data in Table 3, the zeolite ceramsite of Examples 1 to 4 and Comparative Examples 1 to 2 has a large single pore volume, a large total pore volume, and an average pore diameter of 7.0568nm to 16.627nm, all of which belong to the mesopore range. However, it should be specially noted that: Comparative Example 1 is a zeolite ceramsite without the addition of stearic acid (pore-forming agent), and its average pore diameter is significantly smaller than that of Examples 1 to 4, which proves that the pore size formed by the escape of CO2 from the high-temperature calcination of phosphorus tailings is within the range of micropore size (less than 2nm); Comparative Example 2 is a zeolite ceramsite without the addition of phosphorus tailings, and its average pore diameter is slightly larger than that of Examples 1 to 4, which again proves that the pores formed during the high-temperature calcination of stearic acid (pore-forming agent) are within the range of mesopore size (2 to 50nm).

[0107] The N2 adsorption-desorption curve and pore size distribution diagram of ZC-01 prepared in Example 1 were plotted separately ( Figure 1 ),from Figure 1 It can be seen that the curve type of ZC-01 is close to the type II adsorption isotherm. In the early stage of adsorption, the isotherm is convex and has an inflection point. The monolayer adsorption reaches equilibrium. As the pressure increases, multilayer adsorption gradually forms. And the H3 type hysteresis loop appears, indicating that the pores of zeolite ceramsite are slit holes formed by the accumulation of ribbon particles, which is convenient for providing more adsorption sites during the adsorption process. The pore size distribution of ZC-01 is concentrated in two size ranges, one is the micropore size of 1.88nm, and the other is the mesopore size of 14.12nm.

[0108] (3) The ZC-01 prepared in Example 1 was tested using an X-ray diffraction analyzer (XRD) and compared with the diffraction file (PDF) card in the standard database. Figure 2 As shown. Figure 2 It can be seen that the diffraction characteristic peaks of the ZC-01 zeolite ceramsite prepared in Example 1 are highly consistent with the diffraction characteristic peaks of type A zeolite.

[0109] (4) The microscopic morphology of ZC-01 prepared in Example 1 was observed by field emission scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Figure 3 As shown. From the SEM photos, we can see the typical A-type zeolite cubic structure, with clear cubic morphology, sharp edges and corners, smooth surface and complete crystal structure. EDS scanning shows that the main elements Si, Al, Na and O of ZC-01 zeolite ceramsite are evenly distributed, without the phenomenon of excessive enrichment of certain elements, which proves that ZC-01 prepared in Example 1 provides a uniform reaction space during the adsorption process.

Claims

1. A method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, characterized in that: The following steps are involved: (1) mixing acidified fly ash, phosphorus tailings, and montmorillonite in a mass ratio of (5-10):(1-5):1, adding stearic acid as a pore-forming agent in a mass ratio of 1% to 5% of the total mass of the acidified fly ash, phosphorus tailings, and montmorillonite to obtain a premixed powder; (2) using ethanol aqueous solution as a dispersant, placing the premixed powder obtained in step (1) in the dispersant, stirring in a constant temperature water bath at 60 to 75° C. for 1 to 4 hours, and then centrifuging and drying to obtain a highly dispersed premixed powder; (3) adding sodium aluminate to the highly dispersed premixed powder obtained in step (2) to adjust the silicon-aluminum ratio to 1: (1-1.5), then adding solid sodium hydroxide, mixing and grinding thoroughly to less than 200 meshes, to obtain a fully mixed powder; (4) pressing the fully mixed powder obtained in step (3) into a shape to obtain a columnar raw material with a diameter of 5 to 8 mm and a length of 8 to 10 mm, drying the raw material, calcining the raw material in a muffle furnace, and naturally cooling the raw material to room temperature to obtain activated ceramsite; (5) Add the activated ceramsite obtained in step (4) into deionized water, and perform a hydrothermal reaction at 75 to 95° C. for 4 to 12 hours. After the reaction is completed, wash and dry to obtain zeolite ceramsite for deep treatment of ammonia nitrogen wastewater.

2. The method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater according to claim 1, characterized in that: In step (1), the acidified fly ash is prepared by a method comprising the following steps: placing fly ash in dilute hydrochloric acid with a mass concentration of 5 to 10%, with the mass ratio of fly ash to dilute hydrochloric acid being 1:(10 to 20), stirring in a constant temperature water bath at 65 to 85° C. for 2 to 4 hours, and then filtering, washing, and drying to obtain the acidified fly ash.

3. The method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater according to claim 1, characterized in that: In step (2), the volume fraction of the ethanol aqueous solution is 10% to 20%, and the mass ratio of the premixed powder to the dispersant is 1:(5 to 10).

4. The method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater according to claim 1, characterized in that: In step (3), the mass ratio of sodium hydroxide to acidified fly ash is 1:

1.

5. The method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater according to claim 1, characterized in that: In step (4), the drying is performed at 95-105°C for 1-2 hours, and the roasting comprises first heating the temperature to 400-500°C at a heating rate of 5-8°C / min, preheating for 30-60 minutes, and then heating the temperature to 550-750°C at a heating rate of 10-12°C / min and keeping the temperature for 1-4 hours.

6. The method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater according to claim 1, characterized in that: In step (5), the mass ratio of activated ceramsite to deionized water is 1:3 to 10.

7. The method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater according to claim 1, characterized in that: In step (5), the hydrothermal reaction is carried out at 75-85° C. for 6 h.

8. The method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater according to claim 1, characterized in that: In step (5), the cleaning and drying comprises: washing with deionized water until the pH of the washing solution is 7 to 10, and then drying at 95 to 105° C. for 1 to 2 hours.

9. A zeolite ceramsite for deep treatment of ammonia nitrogen wastewater, characterized in that: The zeolite ceramsite is prepared by the method for preparing zeolite ceramsite for deep treatment of ammonia nitrogen wastewater according to any one of claims 1 to 8 above.

10. An application of zeolite ceramsite for deep treatment of ammonia nitrogen wastewater as claimed in claim 9, characterized in that: The ammonia nitrogen concentration in the wastewater is 50 mg / L to 200 mg / L, and the dosage of zeolite ceramsite in the wastewater is 40 to 120 g / L.

Images