Modified mayenite, a preparation method thereof and application thereof in removing chlorine ions in water bodies

Abstract

This invention discloses a modified calcium aluminate, its preparation method, and its application in removing chloride ions from water. The preparation method involves heat-treating calcium aluminate under a hydrogen atmosphere to obtain hydrogen-storing calcium aluminate; then, the hydrogen-storing calcium aluminate, a porous carbon source, and an organic solvent are mixed and ball-milled to obtain a ball milling slurry. The nanoscale cage-like structure of the calcium aluminate stores hydrogen. During ball milling, a porous carbon source and an organic solvent are added to modify the calcium aluminate. The high surface area of ​​the porous carbon carrier and the erosive effect of the organic solvent cause the calcium aluminate flakes to peel off. The mechanical energy of ball milling releases the hydrogen stored in the calcium aluminate. This hydrogen, in conjunction with the organic solvent, increases the specific surface area of ​​the resulting calcium aluminate through a combined mechanism of gas release, physical fragmentation, and solvent-assisted dispersion, achieving highly efficient chloride removal.

Description

Technical Field

[0001] This invention relates to a modified calcium aluminum stone, its preparation method, and its application in removing chloride ions from water, belonging to the field of wastewater treatment technology. Background Technology

[0002] With the rapid advancement of industrial civilization and the accelerating pace of urbanization, numerous industries such as chemicals, pharmaceuticals, printing and dyeing, and electroplating are flourishing, with continuously expanding production scales and increasingly complex production processes. These industries use large quantities of chlorine-containing compounds as raw materials, solvents, or reaction media in their production processes, making chlorine-containing wastewater a common byproduct of industrial production. Simultaneously, with the improvement of people's living standards, various chlorine-containing daily chemical products are widely used, leading to a quiet increase in chloride ion content in domestic sewage. Furthermore, in some areas, to meet industrial and domestic water demands, the unreasonable extraction and utilization of groundwater or surface water with high chlorine content further exacerbates the generation of chlorine-containing wastewater. The discharge of chlorine-containing wastewater is increasing daily; its composition is complex, its concentration fluctuates greatly, and it possesses strong corrosiveness and toxicity, posing a serious threat to the ecological environment, human health, and industrial production, and has become an environmental problem urgently needing to be solved.

[0003] Traditional dechlorination technologies mainly include chemical precipitation, ion exchange, evaporation and concentration, and solvent extraction. Ion exchange is only suitable for low-concentration Cl with simple components. - Wastewater can only be recycled, resulting in high costs and secondary pollution. Evaporation concentration is inherently energy-intensive; solvent extraction has low removal rates, high costs and energy consumption, and complex operation. However, the development of these methods is limited by the difficulty in recovering chloride removal products and the high cost of chloride removal agents, hindering their widespread implementation. Among these technologies, chemical precipitation, with its simple operation and ability to treat high-concentration chlorine wastewater, has become the most mature dechlorination method and is the most widely used desulfurization wastewater treatment method in thermal power plants worldwide. Chlorination chemical precipitation methods mainly include layered double hydroxides, ultra-high lime-alumina methods, silver methods, copper powder methods, and bismuth oxide methods. However, challenges remain regarding high chemical costs, excessive dosage, and the management of generated sludge. Summary of the Invention

[0004] The purpose of this invention is to provide a modified calcium aluminum stone, its preparation method, and its application in removing chloride ions from water. The resulting calcium aluminum stone has an increased reaction surface area, which can improve the dechlorination efficiency of calcium aluminum stone and reduce the dechlorination cost.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing modified calcium aluminum stone involves heat-treating calcium aluminum stone in a hydrogen atmosphere to obtain hydrogen-storing calcium aluminum stone; then mixing and ball-milling the hydrogen-storing calcium aluminum stone, porous carbon source, and organic solvent.

[0006] Preferably, the preparation method of calcium aluminum stone is to mix calcium source and aluminum source, calcine, cool to room temperature and then pulverize.

[0007] Preferably, the calcium source is one or more of calcium phosphate, calcium chloride, calcium oxide, calcium carbonate, calcium sulfate, calcium acetate, calcium hydrogen phosphate, and calcium citrate; The aluminum source is one or more of the following: aluminum sulfate, alumina, aluminum chloride, polyaluminum chloride, polyaluminum ferric silicate, polyaluminum sulfate, polyaluminum phosphate chloride, polyaluminum ferric phosphate, and basic aluminum sulfate silicate.

[0008] Preferably, the molar ratio of Ca in the calcium source to Al in the aluminum source is (0.2-1.25):1; The calcination conditions are: 800-1500℃, 1-5h.

[0009] Preferably, in a hydrogen atmosphere, the amount of hydrogen used is 0.1-0.5 wt% of the mass of calcium aluminum stone; The heat treatment conditions are: 1000-1500℃, 1-3h.

[0010] Preferably, the porous carbon source is one or more of the following: sludge, wood, charcoal powder, plant straw, animal bones, lignite, and anthracite. The mass ratio of hydrogen storage calcium aluminum stone to porous carbon source is 1:(0.01-0.05).

[0011] Preferably, the organic solvent is one or more selected from ethanol, acetone, toluene, n-hexane, cyclohexane, and styrene; The ratio of hydrogen storage calcium aluminum stone to organic solvent is 1g:(0.5-2.5)mL.

[0012] Preferably, the ball milling conditions are: ball-to-material ratio (5-10):1, 100-500 r / min, 0.5-4 h.

[0013] Modified calcium aluminum stone prepared by any of the above methods.

[0014] The application of modified calcium aluminum stone prepared by any of the above methods in the removal of chloride ions from water, wherein the pH of the water is 8-12, the dosage of modified calcium aluminum stone is 1-30 wt% of the water mass, and the reaction time is 1-30 h.

[0015] The beneficial effects of this invention are as follows: This invention combines hydrogen storage using calcium aluminate (CA) with mechanical ball milling, and introduces two additives: a porous carbon source and an organic solvent. First, hydrogen storage is achieved using CA's unique nanoscale cage-like structure. Then, mechanical ball milling fragments the CA's surface. During the milling process, the high surface area of ​​the porous carbon carrier and the erosive effect of the organic solvent cause the CA's flake-like structure to peel off. Simultaneously, the hydrogen released during the milling process further promotes pore formation in the organic solvent. The mechanical energy of the milling not only releases hydrogen but also works synergistically with the organic solvent. Through a composite mechanism of gas release, physical fragmentation, and solvent-assisted dispersion, the specific surface area of ​​CA's is significantly increased, achieving highly efficient chlorine removal.

[0016] During the dechlorination process, the unreleased hydrogen in the calcium aluminate provides additional reaction driving force after the calcium aluminate is hydrogenated. In addition to the hydration reaction of the calcium aluminate itself, the H2O occupying the cage-like structure vacancies during hydrogen storage also contributes to this process. - It will be quickly displaced by water and generate OH. - This creates a self-catalytic effect, accelerating the entire hydration reaction.

[0017] This method is simple, easy to operate, and fast in preparation. Furthermore, the use of inexpensive alumina and calcium oxide as raw materials effectively reduces the cost of chloride ion removal. Using the calcium alumina chloride removal method of this invention, the main chloride removal product is Frederick salt, which not only avoids waste of raw materials but also reduces subsequent processing costs. Simultaneously, the product is easy to recover and can be used to adsorb other heavy metal ions, achieving resource recycling. Attached Figure Description

[0018] Figure 1 The image shows the SEM image of the calcium aluminum stone obtained in step (2) of Example 3; Figure 2 The image shown is a SEM image of the modified calcium aluminum stone obtained in step (4) of Example 3. Detailed Implementation

[0019] Experimental methods not specifically described in the following examples are generally determined according to national standards; if no corresponding national standard exists, they are performed according to generally accepted international standards or the standards proposed by relevant enterprises. Unless otherwise stated, all parts are parts by weight, and all percentages are weight percentages.

[0020] Example 1: Preparation of modified calcium aluminum stone and method for removing chloride ions from wastewater, comprising the following steps: (1) Weigh the corresponding proportions of calcium oxide and aluminum oxide using electronic level according to the Ca:Al molar ratio of 0.25:1, then put them into a crucible and stir evenly. (2) Place the crucible in a muffle furnace and calcine at 800°C for 1 hour; after calcineation, remove the crucible and cool it to room temperature, then crush the solid powder in the crucible to obtain calcium aluminum stone; (3) Place calcium aluminum stone in a hydrogen atmosphere, with the amount of hydrogen used being 0.1 wt% of the mass of calcium aluminum stone, and heat treat it at 1000℃ for 2 hours to obtain hydrogen storage calcium aluminum stone. (4) In a ball mill, hydrogen-storing calcium aluminum stone and charcoal powder are mixed at a mass ratio of 1:0.02, and organic solvent is added to the ball mill at a solid-liquid ratio of 1g hydrogen-storing calcium aluminum stone:0.5mL organic solvent. The organic solvent is obtained by mixing acetone and cyclohexane at a volume ratio of 4:6. The ball-to-material ratio is 5:1 (the mass ratio of microspheres to hydrogen-storing calcium aluminum stone, with the same unit). The ball mill is run at 100r / min for 0.5h to obtain modified calcium aluminum stone. (5) The modified calcium aluminum stone was added to the wastewater with an original chloride ion concentration of 5325 mg / L and an initial pH of 8. The amount of modified calcium aluminum stone added was 1 wt%. After reacting for 1 h, the concentration of chloride ions in the supernatant after centrifugation was measured by ion chromatography to be 1143 mg / L, and the dechlorination efficiency was 78.54%.

[0021] Example 2: Preparation of modified calcium aluminum stone and method for removing chloride ions from wastewater, comprising the following steps: (1) Weigh the corresponding proportions of calcium oxide and aluminum oxide using an electronic balance according to the Ca:Al molar ratio of 0.5:1, then put them into a crucible and stir evenly. (2) Place the crucible in a muffle furnace and calcine at 1000℃ for 2 hours. After calcineation, remove the crucible and cool it to room temperature. Then, crush the solid powder in the crucible to obtain calcium aluminum stone. (3) Place calcium aluminum stone in a hydrogen atmosphere, with the amount of hydrogen used being 0.2 wt% of the mass of calcium aluminum stone, and heat treat at 1100℃ for 2 h to obtain hydrogen storage calcium aluminum stone. (4) In a ball mill, hydrogen-storing calcium aluminum stone and charcoal powder were mixed at a mass ratio of 1:0.02, and organic solvent was added to the ball mill at a solid-liquid ratio of 1g hydrogen-storing calcium aluminum stone:1.5mL organic solvent. The organic solvent was obtained by mixing acetone and cyclohexane at a volume ratio of 4:6. The ball-to-material ratio was 6:1 (the mass ratio of microspheres to hydrogen-storing calcium aluminum stone, with the same unit). The ball mill was run at 200r / min for 1h to obtain modified calcium aluminum stone. (5) The modified calcium aluminum stone was added to the wastewater with an original chloride ion concentration of 5325 mg / L and an initial pH of 9. The amount of modified calcium aluminum stone added was 5 wt%. After reacting for 2 hours, the concentration of chloride ions in the supernatant after centrifugation was measured by ion chromatography to be 714 mg / L, and the dechlorination efficiency was 86.59%.

[0022] Example 3: Preparation of modified calcium aluminum stone and method for removing chloride ions from wastewater, comprising the following steps: (1) Weigh the corresponding proportions of calcium oxide and aluminum oxide using an electronic balance according to the Ca:Al molar ratio of 0.5:1, then put them into a crucible and stir evenly. (2) Place the crucible in a muffle furnace and calcine at 1100℃ for 3 hours. After calcination, remove the crucible and cool it to room temperature. Then, crush the solid powder in the crucible to obtain calcium aluminum stone. (3) Place calcium aluminum stone in a hydrogen atmosphere, with the amount of hydrogen used being 0.3wt% of the mass of calcium aluminum stone, and heat treat it at 1300℃ for 2h to obtain hydrogen storage calcium aluminum stone. (4) In a ball mill, hydrogen-storing calcium aluminum stone and charcoal powder were mixed at a mass ratio of 1:0.03, and organic solvent was added to the ball mill at a solid-liquid ratio of 1g hydrogen-storing calcium aluminum stone:2mL organic solvent. The organic solvent was obtained by mixing acetone and cyclohexane at a volume ratio of 4:6. The ball-to-material ratio was 8:1 (the mass ratio of microspheres to hydrogen-storing calcium aluminum stone, with the same unit). The ball milling was carried out at 300r / min for 2h to obtain modified calcium aluminum stone. Figure 1 , Figure 2 The images are SEM images of the calcium aluminum stone obtained in steps (2) and (4), respectively. As can be seen from the images, the initial calcium aluminum stone has few exposed platy bodies and is in a densely packed state; however, after ball milling modification, more platy bodies are exposed and the surface area is increased. (5) The modified calcium aluminum stone was added to the wastewater with an initial chloride ion concentration of 5325 mg / L and an initial pH of 10. The amount of modified calcium aluminum stone added was 10 wt%. After reacting for 5 h, the concentration of chloride ions in the supernatant after centrifugation was measured by ion chromatography to be 519 mg / L, and the dechlorination efficiency was 90.25%.

[0023] Example 4: Preparation of modified calcium aluminum stone and method for removing chloride ions from wastewater, comprising the following steps: (1) Weigh the corresponding proportions of calcium oxide and aluminum oxide using an electronic balance according to the Ca:Al molar ratio of 0.25:1, then put them into a crucible and stir evenly. (2) Place the crucible in a muffle furnace and calcine at 1300℃ for 4 hours; after calcine, remove the crucible and cool it to room temperature, then crush the solid powder in the crucible to obtain calcium aluminum stone; (3) Place calcium aluminum stone in a hydrogen atmosphere, with the amount of hydrogen used being 0.4 wt% of the mass of calcium aluminum stone, and heat treat at 1400℃ for 2 h to obtain hydrogen storage calcium aluminum stone. (4) In a ball mill, hydrogen-storing calcium aluminum stone and charcoal powder were mixed at a mass ratio of 1:0.03, and organic solvent was added to the ball mill at a solid-liquid ratio of 1g hydrogen-storing calcium aluminum stone: 2.5mL organic solvent. The organic solvent was obtained by mixing acetone and cyclohexane at a volume ratio of 4:6. The ball-to-material ratio was 9:1 (the mass ratio of microspheres to hydrogen-storing calcium aluminum stone, with the same unit). The ball milling was carried out at 400r / min for 3h to obtain modified calcium aluminum stone. (5) The modified calcium aluminum stone was added to the wastewater with an initial chloride ion concentration of 5325 mg / L and an initial pH of 11. The amount of modified calcium aluminum stone added was 20 wt%. After reacting for 24 h, the concentration of chloride ions in the supernatant after centrifugation was measured by ion chromatography to be 421 mg / L, and the dechlorination efficiency was 92.1%.

[0024] Example 5: Preparation of modified calcium aluminum stone and method for removing chloride ions from wastewater, comprising the following steps: (1) Weigh the corresponding proportions of calcium oxide and aluminum oxide using an electronic balance according to the Ca:Al molar ratio of 0.75:1, then put them into a crucible and stir evenly. (2) Place the crucible in a muffle furnace and calcine at 1200℃ for 4 hours. After calcination, remove the crucible and cool it to room temperature. Then, crush the solid powder in the crucible to obtain calcium aluminum stone. (3) Place calcium aluminum stone in a hydrogen atmosphere, with the amount of hydrogen used being 0.2 wt% of the mass of calcium aluminum stone, and heat treat at 1200℃ for 2 h to obtain hydrogen storage calcium aluminum stone. (4) In a ball mill, hydrogen-storing calcium aluminum stone and charcoal powder are mixed at a mass ratio of 1:0.01, and organic solvent is added to the ball mill at a solid-liquid ratio of 1g hydrogen-storing calcium aluminum stone:1mL organic solvent. The organic solvent is obtained by mixing acetone and cyclohexane at a volume ratio of 4:6. The ball-to-material ratio is 10:1 (the mass ratio of microspheres to hydrogen-storing calcium aluminum stone, with the same unit). The ball mill is run at 300r / min for 3h to obtain modified calcium aluminum stone. (5) The modified calcium aluminum stone was added to the wastewater with an original chloride ion concentration of 4843 mg / L and an initial pH of 11. The amount of modified calcium aluminum stone added was 5 wt%. After 2 hours of reaction, the concentration of chloride ions in the supernatant after centrifugation was measured by ion chromatography to be 166 mg / L, and the dechlorination efficiency was 96.57%.

[0025] Example 6: Preparation of modified calcium aluminum stone and method for removing chloride ions from wastewater, comprising the following steps: A method for improving the removal of chloride ions from wastewater using calcium aluminum silicate via ball milling includes the following steps: (1) Weigh the corresponding proportions of calcium oxide and aluminum oxide using an electronic balance according to the Ca:Al molar ratio of 1:1, then put them into a crucible and stir evenly. (2) Place the crucible in a muffle furnace and calcine at 1400℃ for 5 hours. After calcineation, remove the crucible and cool it to room temperature. Then, crush the solid powder in the crucible to obtain calcium aluminum stone. (3) Place calcium aluminum stone in a hydrogen atmosphere, with the amount of hydrogen used being 0.5 wt% of the mass of calcium aluminum stone, and heat treat at 1400℃ for 2 h to obtain hydrogen storage calcium aluminum stone. (4) In a ball mill, hydrogen-storing calcium aluminum stone and charcoal powder were mixed at a mass ratio of 1:0.05, and organic solvent was added to the ball mill at a solid-liquid ratio of 1g hydrogen-storing calcium aluminum stone: 2mL organic solvent. The organic solvent was obtained by mixing acetone and cyclohexane at a volume ratio of 4:6. The ball-to-material ratio was 10:1 (the mass ratio of microspheres to hydrogen-storing calcium aluminum stone, with the same unit). The ball milling was carried out at 500r / min for 4h to obtain modified calcium aluminum stone. (5) The modified calcium aluminum stone was added to the wastewater with an initial chloride ion concentration of 4843 mg / L and an initial pH of 12. The amount of modified calcium aluminum stone added was 30 wt%. After reacting for 48 h, the concentration of chloride ions in the supernatant after centrifugation was measured by ion chromatography to be 625 mg / L, and the chloride removal efficiency was 87.09%.

[0026] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing modified calcium aluminum stone, characterized in that, The process involves heat-treating calcium aluminum stone in a hydrogen atmosphere to obtain hydrogen-storing calcium aluminum stone; then, the hydrogen-storing calcium aluminum stone, porous carbon source, and organic solvent are mixed and ball-milled.

2. The method for preparing modified calcium aluminum stone according to claim 1, characterized in that, The preparation method of calcium aluminum stone is to mix calcium source and aluminum source, calcine them, cool them to room temperature, and then pulverize them.

3. The method for preparing modified calcium aluminum stone according to claim 2, characterized in that, The calcium source is one or more of the following: calcium phosphate, calcium chloride, calcium oxide, calcium carbonate, calcium sulfate, calcium acetate, calcium hydrogen phosphate, and calcium citrate. The aluminum source is one or more of the following: aluminum sulfate, alumina, aluminum chloride, polyaluminum chloride, polyaluminum ferric silicate, polyaluminum sulfate, polyaluminum phosphate chloride, polyaluminum ferric phosphate, and basic aluminum sulfate silicate.

4. The method for preparing modified calcium aluminum stone according to claim 2, characterized in that, The molar ratio of Ca in the calcium source to Al in the aluminum source is (0.2-1.25):1; The calcination conditions are: 800-1500℃, 1-5h.

5. The method for preparing modified calcium aluminum stone according to claim 2, characterized in that, In a hydrogen atmosphere, the amount of hydrogen used is 0.1-0.5 wt% of the mass of calcium aluminum stone. The heat treatment conditions are: 1000-1500℃, 1-3h.

6. The method for preparing modified calcium aluminum stone according to claim 2, characterized in that, Porous carbon sources include one or more of the following: sludge, wood, charcoal powder, plant straw, animal bones, lignite, and anthracite. The mass ratio of hydrogen storage calcium aluminum stone to porous carbon source is 1:(0.01-0.05).

7. The method for preparing modified calcium aluminum stone according to claim 2, characterized in that, The organic solvent is one or more of ethanol, acetone, toluene, n-hexane, cyclohexane, and styrene; The ratio of hydrogen storage calcium aluminum stone to organic solvent is 1g:(0.5-2.5)mL.

8. The method for preparing modified calcium aluminum stone according to claim 2, characterized in that, The ball milling conditions are: ball-to-material ratio (5-10):1, 100-500 r / min, 0.5-4 h.

9. The modified calcium aluminum stone prepared by the method according to any one of claims 1-8.

10. The use of the modified calcium aluminum stone prepared by the method of any one of claims 1-8 in the removal of chloride ions from water.

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