Unfired fly ash ceramsite, preparation method and application thereof

Abstract

The application discloses a kind of baking-free fly ash ceramsite and its preparation method and application in water treatment.The preparation method includes the following steps: (1) the raw material containing the following components is mixed with water to granulate, and the ceramsite raw material ball is obtained: fly ash 30wt%-60wt%, cement 20wt%-30wt%, active component 10wt%-20wt%, activator 5wt%-15wt%, and hole-expanding agent 1wt%-5wt%; the active component is a mixture of hematite and bauxite residue; (2) the ceramsite raw material ball is aged, steamed and dried to obtain the shaped ceramsite; (3) the shaped ceramsite is immersed in a modified liquid containing Fe 3+ , Al 3+ and Ca 2+ , the pH is adjusted to alkaline, and the baking-free fly ash ceramsite is obtained by heating hydration reaction.The baking-free fly ash ceramsite prepared by the application has high porosity, large specific surface area, large adsorption capacity, fast adsorption rate, can multi-functionally treat various pollutants, and has wide application in composite sewage treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a sinter-free fly ash ceramsite and a preparation method and application thereof. BACKGROUND

[0002] Current main treatment methods for breeding sewage in agriculture include filler adsorption of constructed wetlands and microbial degradation of A / O process, which are mainly used for reducing COD, ammonia nitrogen and other traditional pollutants. However, due to the operation cost and the synergistic effect of coexistence of various pollutants, the reduction of total phosphorus and antibiotics generally faces problems: the conventional filler is a natural mineral, and the adsorption capacity of total phosphorus and antibiotics is limited, so it is difficult to effectively remove total phosphorus and antibiotic pollution; the traditional microbial technology has poor phosphorus removal effect, and the toxicity of antibiotics also inhibits the activity of phosphorus accumulating bacteria, reducing the phosphorus removal efficiency, resulting in the widespread existence of total phosphorus exceeding standard; the operation cost of chemical flocculation and membrane treatment technology is too high, which is not conducive to the popularization in production application; and there is no targeted treatment technology for antibiotics. Therefore, there is still a high concentration of total phosphorus and antibiotics in the effluent of the sewage treatment facility at the present stage, which causes great threat to the ecological environment. In the prior art, the filler can remove various pollutants at the same time, which is a relatively low-cost, easy-to-use and widely applicable technology, and also has biochemical function by biofilm formation, and has good application prospect. Therefore, developing a new filler capable of simultaneously treating total phosphorus and antibiotics can meet the current urgent demand for sewage treatment.

[0003] On the other hand, fly ash is an industrial solid waste with large output, and its harmless treatment, especially resource utilization, is paid more attention in the current solid waste treatment field. Fly ash ceramsite is made of fly ash as the main raw material, mixed with appropriate auxiliary materials, and then measured, mixed, formed and hydrated to form fly ash ceramsite. Fly ash ceramsite is commonly used in the field of building materials, but its application range is also expanding. For example, fly ash ceramsite can be used as an adsorption filler for sewage treatment to effectively reduce the treatment cost. However, the conventional fly ash ceramsite still has problems such as small specific surface area, low porosity and low water absorption, and small adsorption capacity. In addition, the surface lacks active sites such as Fe, Al and Ca, and it is difficult to achieve effective chemical adsorption, so it does not have the effect of removing specific pollutants such as total phosphorus and antibiotics.

[0004] Some ceramsites disclosed in the published patent applications use high-energy sintering to increase the specific surface area or add more high-value raw materials to increase the active sites in order to improve the decontamination effect, which significantly increases the use cost of the ceramsite.

[0005] The Chinese invention patent application with the application publication number CN113651588A uses fly ash and sludge as the main raw materials to make a conventional unburned fly ash ceramsite, which has a certain phosphorus removal function, but the phosphorus removal rate is only 45%-65%, and in the case of continuous upgrading of sewage treatment at the present stage, the practical value is limited.

[0006] The Chinese invention patent application with the application publication number CN114409029A discloses a phosphorus removal ceramsite, a preparation method and application thereof. The phosphorus removal ceramsite takes iron powder and aluminum powder as the core, and takes calcium carbonate and bentonite as the supporting material, and the ceramsite finished product is obtained by sintering. However, the specific surface area of the ceramsite is still small, only about 4m 2 / g, and since the ceramsite is prepared by sintering, the production cost is also high, which is not conducive to the promotion in the water treatment process, and the iron and aluminum components in the finished product also have the possibility of dissolution, and the applicable environment is limited.

[0007] The Chinese invention patent with the publication number CN116262659B also uses solid waste raw materials to sinter and prepare groundwater treatment ceramsite, and also uses zirconium oxychloride additives for doping, which also significantly increases the production cost.

[0008] On the other hand, the treatment of new pollutants such as antibiotics is still in the theoretical research stage. The Chinese invention patents with the publication numbers CN114522672B and CN103949215B both use carbon materials to adsorb and treat antibiotic pollution in wastewater, but the powder carbon material is easy to lose and wear, and it is difficult to achieve stable and efficient removal effect in actual engineering systems such as constructed wetlands. The Chinese invention patent with the publication number CN111686692B uses modified organic metal framework materials to adsorb and treat antibiotics, and the material production cost is high, and the practicality is limited.

[0009] Therefore, in view of the above related prior art, the inventors believe that the existing ceramsite filler technology has the problems of insufficient treatment capacity and treatment rate of total phosphorus and new pollutants such as antibiotics, and lacks the effect of cooperative removal of composite pollution, and an improved scheme is needed to obtain a ceramsite filler that can efficiently and quickly achieve stable and standard composite wastewater pollution, and realize the cooperative treatment of total phosphorus and antibiotic pollution. SUMMARY

[0010] In view of the problems of insufficient treatment capacity and rate of total phosphorus and new antibiotics pollution and lack of targeted treatment effect in the existing ceramsite technology, the application provides a baking-free ceramsite based on main raw materials such as fly ash, active components and hole expanding agent and a preparation method and efficient treatment application of the baking-free ceramsite to composite sewage. The preparation method is simple and easy to operate, raw materials are easy to obtain, and the baking-free fly ash ceramsite has high porosity, large specific surface area, large adsorption capacity and fast adsorption rate, can multifunctionally treat various pollutants, and has a wide application in composite sewage treatment.

[0011] A preparation method of baking-free fly ash ceramsite, comprising the following steps:

[0012] (1) uniformly mixing raw materials containing the following components with water to granulate, to obtain ceramsite raw material balls:

[0013]

[0014] The active component is a mixture of hematite and bauxite residue;

[0015] The baking-free fly ash ceramsite formed by the above raw material components is uniformly distributed with rich calcium, iron and aluminum active sites on the surface and in the pore channel, which can adsorb phosphate and antibiotic molecules through electrostatic action and other ways, has strong adsorption treatment effect, and can also serve as a stable substrate based on the pre-arranged Fe, Al and Ca sites of fly ash and active components, which is beneficial to subsequent impregnation modification treatment;

[0016] (2) aging, steaming and air drying the ceramsite raw material balls to obtain shaped ceramsite;

[0017] (3) impregnating the shaped ceramsite in a modification liquid containing Fe 3+ , Al 3+ and Ca 2+ , adjusting the pH to alkaline, and carrying out hydration reaction under heating to obtain the baking-free fly ash ceramsite.

[0018] Through optimization of the water addition amount and water addition mode, the powder can be uniformly formed into balls, the raw material balls can be fully rolled in the granulator, and the shaping is uniform and regular.

[0019] In a preferred example, in step (1), the water is added in an amount of 25% to 40% based on 100% of the total mass of the raw materials.

[0020] In a preferred example, in step (1), the water is added in multiple times in a spraying mode.

[0021] In step (1), the granulation can be carried out by using a granulator. Further, the rotation speed of the granulator during the granulation can be 20 to 30 rpm, and the disc angle can be 30° to 60°.

[0022] In step (1), the sum of the mass percentages of the fly ash, the cement, the active component, the activator and the pore-expanding agent can be 100%.

[0023] Increasing the fineness of the raw materials can improve the reaction efficiency in the granulation process and increase the strength of the ceramsite finished product. In step (1), the fly ash, the cement, the active component, the activator and the pore-expanding agent are all ground to pass through a 200-mesh sieve and dried at 100-105°C before being mixed.

[0024] In step (1), the fly ash can be high-calcium fly ash.

[0025] In step (1), the content of calcium oxide in the fly ash is greater than 10 wt%.

[0026] In step (1), the cement can be Portland cement.

[0027] In step (1), the mass ratio of the hematite to the bauxite residue in the active component can be 2:1-3.

[0028] In a preferred embodiment, in step (1), the activator is a mixture of lime and sodium metasilicate. The lime and sodium metasilicate provide an alkaline environment for the reaction, jointly activate the fly ash to undergo hydration and polymerization, generate geopolymer product structures, facilitate granulation and molding, and increase the strength of the ceramsite finished product. Further, in the activator, the mass ratio of the lime to the sodium metasilicate can be 1-4:1.

[0029] In a preferred embodiment, in step (1), the pore-expanding agent is sodium bicarbonate. The ceramsite prepared by this preferred scheme has a larger specific surface area and a more abundant pore structure, and exposes more active sites, thereby improving the physical and chemical adsorption capacity of the ceramsite.

[0030] In step (2), the aging can include room temperature aging and dry aging performed in sequence. In a preferred embodiment, the time for the room temperature aging is 30-60 min. In a preferred embodiment, the temperature for the dry aging is 40-60°C, and the time is 30-90 min. The above preferred schemes can increase the initial strength of the ceramsite green balls, reduce the loss rate, and shorten the subsequent curing time.

[0031] High-temperature steam curing of the ceramsite can accelerate the hydration reaction, shorten the time for the ceramsite to stabilize, and prevent the ceramsite from being damaged. In a preferred embodiment, in step (2), the conditions for the steam curing include a steam curing temperature of 60-90°C, a steam curing environment relative humidity of 90%-100%, and a steam curing time of 5-10 days.

[0032] In step (2), the temperature of the air-drying can be room temperature to 50℃, and the time can be 2 to 3 days.

[0033] In the preparation of the non-burned fly ash ceramsite, Ca, Fe and Al components are introduced in advance by fly ash and active components, which can be used as a modified template. During the subsequent heating hydration reaction in the modified liquid, the Ca, Fe and Al sites on the surface will quickly deposit and grow into layered double hydroxides (LDHs), forming a uniform distribution and stable structure surface modification. The non-burned fly ash ceramsite surface has more types of functional groups and spatial structures, further optimizing the adsorption treatment performance.

[0034] In step (3), the molar ratio of Fe 3+ and Al 3+ to Ca 2+ in the modified liquid can be 1:1 to 4.

[0035] In step (3), the molar ratio of Fe 3+ and Al 3+ in the modified liquid can be 0.25 to 4:1.

[0036] Further, in step (3), the molar ratio of Fe 3+ , Al 3+ and Ca 2+ in the modified liquid can be 1:1:2 to 8.

[0037] In step (3), the molar concentration of Fe 3+ in the modified liquid can be 0.1 to 0.4M, the molar concentration of Al 3+ can be 0.1 to 0.4M, and the molar concentration of Ca 2+ can be 0.2 to 0.8M.

[0038] In step (3), the source of Fe 3+ , Al 3+ and Ca 2+ in the modified liquid can be FeCl3, AlCl3 and CaCl2.

[0039] In step (3), the ratio of the amount of the shaped ceramsite to the modified liquid can be 1g:4 to 6mL.

[0040] In an embodiment, in step (3), the pH is adjusted to 10 to 12, preferably 11 to 12.

[0041] In step (3), the temperature of the heating hydration reaction can be 60 to 80℃, and the time can be 2 to 4h.

[0042] The application further provides the unfired fly ash ceramsite prepared by the preparation method.

[0043] The application further provides application of the unfired fly ash ceramsite in water treatment.

[0044] As a general inventive concept, the application further provides a sewage treatment method containing phosphorus and / or antibiotics, which uses the unfired fly ash ceramsite to adsorb phosphorus and / or antibiotics in sewage.

[0045] The sewage treatment method containing phosphorus and / or antibiotics can be used in static treatment or dynamic treatment or a combination of both.

[0046] The static treatment can include: adding the unfired fly ash ceramsite into the sewage, standing, and completing adsorption of phosphorus and / or antibiotics in the sewage by the unfired fly ash ceramsite.

[0047] In the static treatment, the total phosphorus concentration in the sewage can be 10-300 mg / L, the antibiotic concentration can be 5-20 mg / L, the initial pH value of the sewage can be 6-8, the adding amount of the unfired fly ash ceramsite can be 5-10 g / L, and the adsorption temperature can be 20-30 DEG C.

[0048] The dynamic treatment can include: limiting the unfired fly ash ceramsite in an adsorption device, and flowing the sewage through the adsorption device and contacting the unfired fly ash ceramsite in the adsorption device, in which process the unfired fly ash ceramsite completes adsorption of phosphorus and / or antibiotics in the sewage.

[0049] In the dynamic treatment, the total phosphorus concentration in the sewage can be 5-10 mg / L, the antibiotic concentration can be 0.1-5 mg / L, the initial pH value of the sewage can be 6-8, the length distribution of the unfired fly ash ceramsite in the adsorption device in the water flow direction can be 0.5-1.0 m, the hydraulic retention time of the sewage in the unfired fly ash ceramsite area can be 0.3-1.5 h, the sewage can flow from bottom to top through the unfired fly ash ceramsite area, can be fully contacted with the unfired fly ash ceramsite, improves the sewage treatment efficiency of the ceramsite, effectively realizes water quality improvement, and the adsorption temperature can be 20-30 DEG C.

[0050] The antibiotics in the application include rifampicin antibiotics and the like.

[0051] Compared with the prior art, the application has the beneficial effects of:

[0052] 1) The unburned fly ash ceramsite of the present application is a layered double hydroxide (LDHs) modified ceramsite.

[0053] 2) The fly ash raw material and active substances used in the present application are mostly industrial waste and natural mineral materials, and other additives are also common and inexpensive industrial materials. The raw material cost is low, which is conducive to the realization of the green concept of "waste treatment with waste" and resource utilization. The preparation process of the present application is also simple and easy to operate, and has the characteristics of low energy and equipment demand, low production and operation cost.

[0054] 3) Compared with the prior art, the ceramsite prepared by the present application has a larger specific surface area and a more abundant pore structure, and also has a certain mechanical strength. The active components in the raw materials provide abundant active sites such as iron, aluminum, calcium and surface hydroxyl groups for the ceramsite, and through pore expansion and impregnation modification, the active sites are fully exposed on the surface of the ceramsite, and through physical adsorption and electrostatic attraction, ligand exchange and other chemical adsorption effects, high-efficiency phosphorus removal can be achieved, and antibiotic compound pollution can also be treated. At the same time, the other physical indexes of the finished ceramsite also meet the standard requirements of CJ / T 299-2008 "Artificial Ceramsite Filter Material for Water Treatment".

[0055] 4) The unburned fly ash ceramsite prepared by the present application can be used as an adsorbent in a wastewater treatment system, and is suitable for various process equipment such as artificial wetlands, biological filters and integrated water purification equipment. It has a high removal rate for high-concentration and low-concentration compound wastewater, and helps to achieve efficient and stable treatment of complex contaminated wastewater. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 The scanning electron microscope (SEM) comparison photos of the main raw material fly ash used in the present application, the formed ceramsite prepared in Example 2, the unburned fly ash ceramsite prepared in Example 5, and the unburned fly ash ceramsite prepared in Example 6 are shown in the figure. Wherein (A) is the fly ash raw material, (B) is the formed ceramsite prepared in Example 2, (C) is the unburned fly ash ceramsite prepared in Example 5, and (D) is the unburned fly ash ceramsite prepared in Example 6.

[0057] Figure 2 The removal effect diagram of the unburned fly ash ceramsite prepared in Example 5 for treating high-concentration rifampicin antibiotic pollution is shown in the figure. In the figure, c0 represents the initial concentration of rifampicin antibiotic.

[0058] Figure 3 The change curve graph of the total phosphorus concentration of the water is shown in the figure, which is used to apply the ceramsite prepared by the present application to a dynamic adsorption water treatment device. DETAILED DESCRIPTION

[0059] The application will be further described in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only used to illustrate the application and not to limit the scope of the application. The operation methods in the following examples without specific conditions are usually according to the conventional conditions or the conditions suggested by the manufacturers.

[0060] Example 1

[0061] A preparation method of the unfired fly ash ceramsite, the detailed steps are as follows:

[0062] (1) The high calcium fly ash with the calcium oxide content of more than 10wt%, the Portland cement, the activator and the sodium bicarbonate pore-expanding agent are respectively ground through the 200 mesh sieve, then dried in the 105℃ oven, then the high calcium fly ash with the mass fraction of 58%, the Portland cement with the mass fraction of 29%, the activator with the mass fraction of 10% and the sodium bicarbonate pore-expanding agent with the mass fraction of 3% are fully stirred and mixed, and the mixed powder is obtained. The activator is the lime and the sodium metasilicate with the mass ratio of 1:1.

[0063] (2) The mixed powder is added into the granulator, the disc angle is 45°, the stirring is rotated at 30rpm, the mixed powder with the water in the form of water mist is gradually added for granulation, and the green balls with the particle size of 5-10mm are obtained.

[0064] (3) The green balls are first placed at room temperature for aging for 30min, then placed in the 50℃ oven for drying for 30min.

[0065] (4) The aged ceramsite green balls are placed in the curing box with the controlled 60℃ and 95% relative humidity for steam curing for 5-10 days, then air dried at room temperature for 2-3 days to obtain the formed ceramsite.

[0066] The formed ceramsite obtained by the above scheme has the porosity of 52%, the specific surface area of 40.8m 2 / g, the water absorption of 54%, the particle strength of 3.4MPa, the crushing rate and the abrasion rate of 3.6%, which meets the requirements of the CJ / T299-2008 Artificial Ceramsite Filter Material for Water Treatment.

[0067] Example 2

[0068] The difference from example 1 is that the active component is also ground through the 200 mesh sieve, then dried in the 105℃ oven, and the high calcium fly ash with the mass fraction of 50%, the Portland cement with the mass fraction of 25%, the active component with the mass fraction of 15%, the activator with the mass fraction of 7% and the sodium bicarbonate pore-expanding agent with the mass fraction of 3% are fully stirred and mixed, wherein the active component is the hematite and the bauxite residue with the mass ratio of 1:1, and the rest is the same, and the formed ceramsite is obtained.

[0069] The formed ceramsite obtained by the above scheme has the porosity of 47%, the specific surface area of 34.2m 2The particle size is 48% / g, the water absorption rate is 48%, the particle strength is 3.5 MPa, and the breakage rate and wear rate are 3.4%, which meets the requirements of "CJ / T299-2008 Artificial Ceramsite Filter Media for Water Treatment".

[0070] Example 3

[0071] 50g of the shaped ceramsite prepared in Example 2 was impregnated in 250mL of a modified solution containing FeCl3 (0.1M), AlCl3 (0.1M) and CaCl2 (0.8M), and stirred for 4h at pH=11-12 and 80℃ to prepare non-fired fly ash ceramsite A.

[0072] The resulting non-fired fly ash ceramsite (A) has a porosity of 55% and a specific surface area of ​​48.3 m². 2 The particle size is 5.5 MPa, the water absorption rate is 51%, the particle strength is 3.5 MPa, and the breakage and wear rates are 3.3%, which meets the requirements of "CJ / T299-2008 Artificial Ceramsite Filter Media for Water Treatment".

[0073] Example 4

[0074] The only difference from Example 3 is that the modified solution contains FeCl3 (0.2M), AlCl3 (0.2M) and CaCl2 (0.8M), while all other components are the same, and non-fired fly ash ceramsite B is prepared.

[0075] The resulting non-fired fly ash ceramsite (B type) has a porosity of 54% and a specific surface area of ​​55.3 m². 2 The particle size is 5.5 g, the water absorption rate is 54%, the particle strength is 3.4 MPa, and the breakage and wear rates are 3.6%, which meets the requirements of "CJ / T299-2008 Artificial Ceramsite Filter Media for Water Treatment".

[0076] Example 5

[0077] The only difference from Example 3 is that the modified solution contains FeCl3 (0.4M), AlCl3 (0.4M) and CaCl2 (0.8M), while all other components are the same, and non-fired fly ash ceramsite C is prepared.

[0078] The resulting non-fired fly ash ceramsite had a C porosity of 51% and a specific surface area of ​​60.1 m². 2 The particle size is 5.5 g, the water absorption rate is 56%, the particle strength is 3.4 MPa, and the breakage and wear rates are 3.3%, which meets the requirements of "CJ / T299-2008 Artificial Ceramsite Filter Media for Water Treatment".

[0079] Example 6

[0080] The difference from Example 5 is only that the same mass of the shaped ceramsite of Example 1 is used to replace the shaped ceramsite of Example 2 for impregnation in the modification liquid, and the rest is the same, to prepare the unfired fly ash ceramsite D.

[0081] The unfired fly ash ceramsite D obtained by the scheme has a porosity of 48%, a specific surface area of 53.2 m 2 / g, a water absorption of 48%, a particle strength of 3.2 MPa, and a crushing rate and abrasion rate of 3.6%, meeting the requirements of CJ / T 299-2008 Artificial Ceramsite Filter Material for Water Treatment.

[0082] Comparative Example 1

[0083] A method for preparing an unfired fly ash ceramsite, which has the same specific preparation scheme and Example 1, and different raw material composition and ratio from Example 1, and the raw material is high-calcium fly ash with a mass fraction of 65% and a calcium oxide content of more than 10 wt%, and 35% of Portland cement.

[0084] The shaped ceramsite obtained by the above scheme has a porosity of 40%, a specific surface area of 10.3 m 2 / g, and a water absorption of 42%. In the implementation process of the synthesis scheme, the granulation and shaping are poor, the shaping rate is low, the particle strength of the prepared ceramsite is only 1.9 MPa, and the practical value is not high.

[0085] Comparative Example 2

[0086] A method for preparing an unfired fly ash ceramsite, which has the same specific preparation scheme and Example 1, and different raw material composition and ratio from Example 1, and the raw material is high-calcium fly ash with a mass fraction of 65% and a calcium oxide content of more than 10 wt%, and 35% of Portland cement.

[0087] The shaped ceramsite obtained by the above scheme has a porosity of 40%, a specific surface area of 10.3 m 2 / g, and a water absorption of 42%. In the implementation process of the synthesis scheme, the granulation and shaping are poor, the shaping rate is low, the particle strength of the prepared ceramsite is only 1.9 MPa, and the practical value is not high.

[0088] Performance test scheme of the ceramsite of each example and comparative example:

[0089] 1) Simulate high-concentration sewage, and respectively measure the adsorption capacity of the ceramsite for total phosphorus and antibiotics. Respectively take 3-4 (about 1 g) of the ceramsite prepared in Examples 1-6 and Comparative Example 2, and respectively treat simulated sewage containing high-concentration total phosphorus and rifampicin antibiotics, to calculate the treatment capacity.

[0090] 2) Use rifampicin antibiotics and total phosphorus pollution to compound into simulated sewage, and select Examples 2 and 5 to measure the treatment capacity of the ceramsite for the combined pollution of total phosphorus and antibiotics at an initial pH in the range of 6-8.

[0091] 3) On the other hand, the ceramsite prepared in Example 2, Example 5 and Comparative Example 2 was used to simulate the treatment effect on dynamic low-concentration sewage in an adsorption column device, and the removal rates of total phosphorus and rifampicin antibiotic pollutants in water were calculated.

[0092] Table 1 shows the performance test results of the ceramsite prepared in each example and comparative example scheme.

[0093] Table 1

[0094]

[0095] The performance test results show that:

[0096] 1. The raw material components and raw material ratio in the ceramsite preparation method have a significant influence on the stability of ceramsite granulation and its physical and chemical properties. In Comparative Example 1, only fly ash and cement were mixed for granulation, which was difficult to form. In Comparative Example 2, the addition of activator made the reaction more complete, and the specific surface area and strength were improved to a certain extent. In Example 1, a pore-expanding agent was added on the basis of Comparative Example 2, so it had a more abundant pore structure and a larger specific surface area. In Example 2, iron, aluminum and other active components were added on the basis of Example 1, so the prepared ceramsite could adsorb phosphate and antibiotics through electrostatic action and ligand exchange with the help of the surface iron and aluminum active sites, thereby improving the treatment capacity and treatment rate of pollutants.

[0097] 2. Examples 3-6 were subjected to impregnation modification, and layered double hydroxides (LDHs) were added to the surface and pores of the ceramsite. Examples 3-5 were subjected to impregnation modification on the basis of Example 2. Since the ceramsite prepared in Example 2 has a uniform distribution of rich Ca, Fe and Al sites on the surface and in the pores, LDHs can use this as a template for rapid deposition and growth, forming a layer of uniformly distributed and structurally stable modified layers, which significantly optimizes the active sites on the surface of the ceramsite and the pore characteristics, thereby having a better treatment effect on phosphate and antibiotics. The treatment effect of Example 5 on rifampicin antibiotic contaminated water is shown in Figure 2 , which shows that it has a high adsorption affinity and adsorption capacity for rifampicin antibiotics, and can achieve a removal rate of more than 90% of rifampicin through static adsorption experiments. Example 6 was subjected to impregnation modification on the basis of Example 1, and since it lacks active site substrates, LDHs can only be simply attached to the surface. As shown in Figure 1 , the electron microscopy characterization shows that the formation of LDHs layers on Example 6 is not sufficient, the surface distribution is less, and the structure is not stable, which will be lost during use.

[0098] 3. The SEM of the main raw material fly ash and the formed ceramsite of Example 2, as well as the prepared unfired fly ash ceramsite of Example 5 and Example 6, is shown in Figure 1The SEM images of the fly ash raw material (A), the shaped ceramsite prepared in Example 2 (B), the unfired fly ash ceramsite prepared in Example 5 (C), and the unfired fly ash ceramsite prepared in Example 6 (D) are shown in Figure 1. The fly ash raw material (A) has a relatively agglomerated particle, a smooth surface, and few channels, and is a dense vitreous structure. The surface of the shaped ceramsite (B) prepared from the fly ash combined with other components is obviously rough, and the folds and channels are significantly increased. The unfired fly ash ceramsite (C) obtained by impregnation modification on this basis shows an obvious LDHs modified lamellar structure in the electron microscope image, and the channel structure and surface properties are further optimized. In comparison, the surface of the ceramsite (D) without the addition of active components after impregnation modification fails to form an effective and extensive LDHs modified lamellar structure, indicating the importance of the pre-addition of active site substrates for impregnation modification.

[0099] 4. The treatment of compound sewage containing different antibiotics and total phosphorus by using the ceramsite prepared in Example 2 and Example 5 and Example 6, and the results are shown in Table 2. The ceramsite prepared in Example 2 has more exposed Ca / Fe / Al active sites, and the surface has a strong positive charge, so it can adsorb the negatively charged total phosphorus and rifampicin through electrostatic interaction. However, when the two pollutants coexist, there is a competition effect, so the treatment efficiency of the compound sewage decreases significantly compared with the single treatment. Example 5 adjusts the spatial structure and charge characteristics of the ceramsite surface through impregnation modification, and can adsorb phosphate through electrostatic interaction and ligand exchange mechanism, and can physically adsorb rifampicin by using the large specific surface area and pore structure; at the same time, the LDHs modification obtained by impregnation modification adds rich surface hydroxyl groups to the ceramsite, which can adsorb rifampicin molecules also with rich oxygen-containing functional groups through extensive hydrogen bonding. Therefore, Example 5 also has good removal rate when treating compound sewage containing total phosphorus and rifampicin, and due to the improvement of the surface hydroxyl groups on the charge characteristics, it can achieve good treatment effect in a wider pH value range. Example 6 has poor impregnation modification effect due to the lack of active site substrates, so the treatment efficiency also decreases to a certain extent when treating synergistic pollution.

[0100] Table 2

[0101]

[0102] 5. The dynamic phosphorus removal test of low-concentration simulated phosphorus-containing wastewater by using the ceramsite prepared in Example 2, Example 5 and Comparative Example 2 of the present application, and the results are shown in Table 3. Figure 3The ceramsite prepared in Example 2 and Example 5 can achieve efficient and stable phosphorus removal for wastewater containing phosphorus, wherein the ceramsite prepared in Example 5 has a faster phosphorus removal rate and maintains a phosphorus removal rate of 99% for a long time thereafter, and the ceramsite prepared in Example 2 can also achieve a phosphorus removal rate of more than 90% after 4h of device operation. Although the ceramsite prepared in Comparative Example 2 can also achieve a phosphorus removal rate of 95% at one time, the phosphorus removal is slow, and the phosphorus removal capacity is small, and the phosphorus removal effect is significantly weakened after the adsorption tends to be saturated in the later period, and the wastewater phosphorus removal cannot be achieved stably and durably.

[0103] In summary, the present application has the following remarkable features:

[0104] First, the doping of iron, aluminum and calcium components in the granulation process has a significant effect on the subsequent impregnation modification treatment:

[0105] a) Provide a uniform and abundant active site substrate on the surface and inside the pores of the ceramsite in advance, and when impregnation modification is performed, the crystal deposition will be templated on these sites, so that the LDHs surface modification can quickly grow and form, and can also be more uniformly distributed.

[0106] b) Using stable iron and aluminum oxides as the deposition substrate of LDHs, the LDHs are modified on the rough surface and inside the pores of the ceramsite, which can stabilize the structure of LDHs and prevent them from being damaged and lost in application.

[0107] Second, the impregnated modified ceramsite has a significant effect on the treatment of total phosphorus and antibiotic pollution:

[0108] A) The surface of the ceramsite without impregnation modification has strong positive charge, and mainly adsorbs through electrostatic interaction, and the adsorption of total phosphorus and antibiotics competes with each other.

[0109] B) After impregnation modification, the surface space structure and charge characteristics of the ceramsite are further improved, and can adsorb phosphate through electrostatic interaction and ligand exchange mechanism, and can physically adsorb antibiotic molecules by using a large specific surface area and pore structure; at the same time, the LDHs modification obtained by impregnation modification adds abundant surface hydroxyl groups to the ceramsite, which can adsorb antibiotic molecules with abundant oxygen-containing functional groups through extensive hydrogen bonding.

[0110] C) Due to the improvement of the charge characteristics of the surface hydroxyl groups formed by the LDHs modification, both total phosphorus and antibiotic pollution can have high treatment efficiency when treating complex wastewater, so the prepared impregnated modified ceramsite can use different reaction mechanisms to cooperatively remove complex pollution, and to some extent, effectively reduces the influence of the competition effect on wastewater adsorption treatment.

[0111] It is to be understood that even though numerous characteristics and embodiments of the application have been set forth in the foregoing disclosure, the details can be varied without departing from the application, which is defined by the claims.

Claims

1. A method for preparing a non-fired fly ash ceramsite, characterized in that, The preparation method comprises the following steps: (1) mixing raw materials containing the following components and granulating with water to obtain ceramic raw material balls: the active component is a mixture of hematite and bauxite residue; (2) aging, steaming and air-drying the ceramic raw material balls to obtain shaped ceramic particles; (3) the shaped ceramsite is immersed in a modified liquid containing Fe 3+ , Al 3+ , and Ca 2+ , the pH is adjusted to alkaline, and a hydration reaction is heated to obtain the unfired fly ash ceramsite.

2. The production method according to claim 1, characterized by, in step (1): the amount of water added is 25%-40% based on the total mass of the raw materials; the water is added in multiple times in a spraying manner; the granulation is performed by using a granulator; the rotating speed of the granulator during the granulation is 20-30 rpm, and the disc angle is 30°-60°; the sum of the mass percentages of the fly ash, the cement, the active component, the activator and the pore-expanding agent is 100%; the fly ash, the cement, the active component, the activator and the pore-expanding agent are all ground to pass through a 200-mesh screen and dried at 100-105 ℃ before being mixed; 3. The preparation method according to claim 1, characterized in that, in step (1): the fly ash is high-calcium fly ash, and the content of calcium oxide is greater than 10 wt%; the cement is Portland cement; in the active component, the mass ratio of the hematite to the bauxite residue is 2:1-3; the activator is a mixture of lime and sodium metasilicate; in the activator, the mass ratio of the lime to the sodium metasilicate is 1-4:1; the pore-expanding agent is sodium bicarbonate.

4. The method of claim 1, wherein, in step (2): the aging comprises room temperature aging and drying aging performed in sequence; the time for the room temperature aging is 30-60 min; the temperature for the drying aging is 40-60 ℃, and the time is 30-90 min; the steaming conditions include a steaming temperature of 60-90 ℃, a steaming environment relative humidity of 90%-100% and a steaming time of 5-10 days; the air-drying temperature is room temperature-50 ℃, and the time is 2-3 days.

5. The preparation method according to claim 1, characterized in that, in step (3): The sum of the moles of Fe 3+ , Al 3+ in the modification liquid is in a molar ratio of 1:1 to 4 with respect to Ca 2+ . The molar ratio of Fe 3+ and Al 3+ in the modification liquid is 0.25-4:

1. In the modified liquid, Fe 3+ The molar concentration is 0.1–0.4 M, Al 3+ The molar concentration is 0.1–0.4 M, Ca 2+ The molar concentration is 0.2–0.8 M; The modified liquid contains Fe 3+ Al 3+ and Ca 2+ The sources are FeCl3, AlCl3 and CaCl2; the ratio of the amount of the shaped ceramic particles to the amount of the modification liquid is 1 g:4-6 mL; the pH value is adjusted to 10-12; the temperature for the heating hydration reaction is 60-80 ℃, and the time is 2-4 h.

6. The method of claim 1, wherein, in step (3): The molar ratio of Fe 3+ , Al 3+ and Ca 2+ in the modification liquid is 1:1:2-8; the pH value is adjusted to 11-12.

7. The unfired fly ash ceramic particles prepared by the preparation method according to any one of claims 1-6.

8. The application of the unfired fly ash ceramic particles according to claim 7 in water treatment.

9. Use according to claim 8, characterized in that, The unfired fly ash ceramic particles are used for adsorbing phosphorus and / or antibiotics in water.

10. A method for the treatment of sewage containing phosphorus and / or antibiotics, characterized in that, The unfired fly ash ceramic particles according to claim 7 are used for adsorbing phosphorus and / or antibiotics in sewage.

11. The phosphorous and / or antibiotic containing wastewater treatment method of claim 10, wherein, The sewage treatment is performed in a static treatment mode, a dynamic treatment mode or a combination of the two modes; the static treatment comprises the following steps: adding the unfired fly ash ceramic particles into the sewage, standing and completing the adsorption of the unfired fly ash ceramic particles to the phosphorus and / or antibiotics in the sewage; in the static treatment, the total phosphorus concentration in the sewage is 10-300 mg / L, the antibiotic concentration is 5-20 mg / L, the initial pH value of the sewage is 6-8, the addition amount of the unfired fly ash ceramic particles is 5-10 g / L, and the adsorption temperature is 20-30 ℃. The dynamic treatment comprises: limiting the non-burned fly ash ceramsite in an adsorption device, and flowing the sewage through the adsorption device and contacting with the non-burned fly ash ceramsite in the adsorption device, in the process, the non-burned fly ash ceramsite completes adsorption of phosphorus and / or antibiotics in the sewage. In the dynamic treatment, the total phosphorus concentration in the sewage is 5-10 mg / L, the antibiotic concentration is 0.1-5 mg / L, the initial pH value of the sewage is 6-8, the length distribution of the non-burned fly ash ceramsite in the adsorption device in the water flow direction is 0.5-1.0 m, the hydraulic retention time of the sewage in the non-burned fly ash ceramsite area is 0.3-1.5 h, the sewage flows through the non-burned fly ash ceramsite area from bottom to top, and the adsorption temperature is 20-30 DEG C.

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